Homebrew_PCBs

----- Original Message -----
From: "mr_gees100_peas" <geovar13@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, March 24, 2004 10:01 AM
Subject: [Homebrew_PCBs] to drill or not to dril?


>
> Hi I've ben reading this group for a while and I feel confident
> enough to make my firt PCB. I decided to use the PnP transfer paper
> and iron it on. Right now I manage to transfer my design to a copper
> bard fairly well. The thing is that I see all those holes and they
> are so smal. I hear some people drill the holes after they etch
> becase they can use the hole as a guide. Well, I tried driling a few
> holes in a practice pice of copper board nd I keep missing the mark.
> The board an't een etch yet but I wondering if I should drill the
> holes fist that way I can add more resist in case I screw up.
>
> My second question is about sharpie pen. When I was transfering my
> desing a few pads and trces did not transfer properly. I took a
> sharpie pen and fille in the missing gap. Will the sharpie resist
> ferric cloride or will it fail?
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

>
> Hi I've ben reading this group for a while and I feel confident
> enough to make my firt PCB. I decided to use the PnP transfer paper
> and iron it on. Right now I manage to transfer my design to a copper
> bard fairly well. The thing is that I see all those holes and they
> are so smal. I hear some people drill the holes after they etch
> becase they can use the hole as a guide. Well, I tried driling a few
> holes in a practice pice of copper board nd I keep missing the mark.
> The board an't een etch yet but I wondering if I should drill the
> holes fist that way I can add more resist in case I screw up.
>

>I personally always dill before etch, but I use a completely different
>process, which includes, plating the holes, and using plated tin as the etch
>resist.

> I etch then drill but then I'm not doing plated through holes.
>
> To do a good drilling job you really need a drill press and carbide
> bits. the HS steel ones just wear out too quickly though the aren't
> as brittle as carbide. You can get a small drill press for well
> under $100 and the dremel kits are reasonably priced, too. Because a
> drill press has a lot of other uses, I see it as a no-brainer
> acquisition.
>
> I use a cross sliding vise with my drill press. once I have the vise
> lined up and the board aligned to the vise it becomes very easy to
> drill holes with in a few mils of the target.
>
> Still, I hate drilling. Its the worst part of the process for me so
> I bias towards surface mount components. Mixed through-hole and smt
> works pretty well though you will have to do more vias.
>
>

> On Wed, 24 Mar 2004 15:01:19 -0000, mr_gees100_peas <geovar13@h...>
> wrote:
>
> >
> > Hi I've ben reading this group for a while and I feel

> > enough to make my firt PCB. I decided to use the PnP transfer

> > and iron it on. Right now I manage to transfer my design to a

> > bard fairly well. The thing is that I see all those holes and they
> > are so smal. I hear some people drill the holes after they etch
> > becase they can use the hole as a guide. Well, I tried driling a

> > holes in a practice pice of copper board nd I keep missing the

> > The board an't een etch yet but I wondering if I should drill the
> > holes fist that way I can add more resist in case I screw up.
> >
>
>
> I know that a hand-fed drill will always center very easily in the

> it is really just aiming close to it and drill.
> If you have problems try to use no drill press, hold a small

> spindle
> in your hand and drill manually.
> Of course you can't use carbide drills. get HSS and grind them

> and then.
> (easy enough to grind).
>
> The aiming is slightly harder with a drill press because the drill

> really move,
> you have to be spot on with aiming or let the board move.
> It all depends on the quality of equipment you use. a good drill

> with no runout
> and a very sharp bit drills very easy, so it is very easy to drill

> edge of the hole.
> A rather dull HSS bit in a bad wobbly spindle will center itself

> better.
>
> If you need no high-quality hole walls it is really fast to work

> handheld drill.
> you will not break HSS bits.
>
>
> I do not like the "add more copper when i screw up" approach.
>
> Also make BIG pads! the standard pads are for throughhole plating.
>
> ST

----- Original Message -----
From: "Markus Zingg" <m.zingg@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, March 24, 2004 11:18 AM
Subject: [Homebrew_PCBs] plated tin as the etch resist


> On Wed, 24 Mar 2004 10:16:56 -0500, Jeremy Taylor wrote:
>
> >I personally always dill before etch, but I use a completely different
> >process, which includes, plating the holes, and using plated tin as the
etch
> >resist.
>
> Intersting. I do the same thing, but I use photoresist laminate to
> avoid etching the just plated holes. Could you elaborate a bit on how
> you do your through hole plating? I'm just curious how others do it
> you know.
>
> Markus
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

> Also, it is worth getting a machined pin socket in 300 and 600 for
> using as a template for drilling.
>
>
> Dave
>

>
> Hi I've ben reading this group for a while and I feel confident
> enough to make my firt PCB. I decided to use the PnP transfer paper
> and iron it on. Right now I manage to transfer my design to a

> bard fairly well. The thing is that I see all those holes and they
> are so smal. I hear some people drill the holes after they etch
> becase they can use the hole as a guide. Well, I tried driling a

> holes in a practice pice of copper board nd I keep missing the

> The board an't een etch yet but I wondering if I should drill the
> holes fist that way I can add more resist in case I screw up.
>
> My second question is about sharpie pen. When I was transfering

> desing a few pads and trces did not transfer properly. I took a
> sharpie pen and fille in the missing gap. Will the sharpie resist
> ferric cloride or will it fail?

> On Wed, 24 Mar 2004 17:15:35 -0000, Phil <phil1960us@y...> wrote:
>

>
> I totally disagree on the carbide is the only way topic.
> With a HSS bit you can easily do one board and they are very easy

> sharpen.
>
> You can drill without a drill stand, which self centers the drill.
>
> The problem was centering of the drill.
> carbide and a drill stand will NOT solve this problem, quite the

>
> I do agree that carbide drills are much better for FR4 but it will

> solve
> the problem for which help was needed.
>
> ST

> --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
> <stefan_trethan@g...> wrote:
> > On Wed, 24 Mar 2004 17:15:35 -0000, Phil <phil1960us@y...> wrote:
> >
> ...
> >
> > I totally disagree on the carbide is the only way topic.
> > With a HSS bit you can easily do one board and they are very easy
> to
> > sharpen.
> >
> > You can drill without a drill stand, which self centers the drill.
> >
> > The problem was centering of the drill.
> > carbide and a drill stand will NOT solve this problem, quite the
> opposite.
> >
> > I do agree that carbide drills are much better for FR4 but it

> not
> > solve
> > the problem for which help was needed.
> >
> > ST
>
> I wouldn't say the only way but I much prefer carbide plus a drill
> press. My quality improved quite a bit once I dumped HSS. I was
> having to resharpen before I finished a board. With my cross

> vise and good lighting, I can get a clean/aligned hole every time.

> really like that sharpening is not part of my ritual any more. One
> less thing to do.

> DRILL
> first, and then etch. The holes serve as "targets" for laying on the
> film for
> photo-resist exposure. This is probably the better method, IF you can
> drill
> accurately.


> Jan Rowland
> Old Troll
>

> And while discussing methods of putting holes in boards, don't forget
> that you can laser thru the top copper, all the fiberglass and down
> TO, but NOT THRU the bottom copper. Makes cool blind thru holes.
>
>

> With my cross sliding vice...

On Wednesday, Mar 24, 2004, at 10:01 US/Eastern, mr_gees100_peas wrote:

>
> Hi I've ben reading this group for a while and I feel confident
> enough to make my firt PCB. I decided to use the PnP transfer paper
> and iron it on. Right now I manage to transfer my design to a copper
> bard fairly well. The thing is that I see all those holes and they
> are so smal. I hear some people drill the holes after they etch
> becase they can use the hole as a guide. Well, I tried driling a few
> holes in a practice pice of copper board nd I keep missing the mark.
> The board an't een etch yet but I wondering if I should drill the
> holes fist that way I can add more resist in case I screw up.
>
> My second question is about sharpie pen. When I was transfering my
> desing a few pads and trces did not transfer properly. I took a
> sharpie pen and fille in the missing gap. Will the sharpie resist
> ferric cloride or will it fail?
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

> with manual drilling it is not easier to drill first, i would say
> it is even harder as you have to aim with the same precision and
> you have no guiding hole.

> Phil wrote:
>
> > With my cross sliding vice...
>
> Any recommendations on a sliding vice that has metered action (hash
> marks on the controls for 10 mil increments or whatever)? I took

> look at what was available locally at Harbor Freight and they were

> rather large and crude, with a lot of slop. They also were too

> a Dremel drill press to have any stroke left.
>
> I imagine something made for use by jewelers would be more suitable

> a typical machine shop cross-vice.
>
> -Johnathan

> You know, I've been wondering why people drill holes at all.
> How about SMDIP (Surface mount DIP) instead of SMT?
> I.e. design your board so that the components mount on the
> trace side of the board. To mount DIPs, bend the legs out 90 degrees
> and solder it down like a surface mount device. You would have to

> the width between the rows of pads to account for the extra width.

> Eagle's Offset Pads would probably do the trick. You can also

> mount normal, visible, passive components. Drill holes for

> and things that need physical strength. You could probably do double
> sided boards like this, even with components on both sides.
> Drilling the vias, of course.
>
> Regards,
> JJ
>
> On Wednesday, Mar 24, 2004, at 10:01 US/Eastern, mr_gees100_peas

>
> >
> > Hi I've ben reading this group for a while and I feel

> > enough to make my firt PCB. I decided to use the PnP transfer

> > and iron it on. Right now I manage to transfer my design to a

> > bard fairly well. The thing is that I see all those holes and they
> > are so smal. I hear some people drill the holes after they etch
> > becase they can use the hole as a guide. Well, I tried driling a

> > holes in a practice pice of copper board nd I keep missing the

> > The board an't een etch yet but I wondering if I should drill the
> > holes fist that way I can add more resist in case I screw up.
> >
> > My second question is about sharpie pen. When I was

> > desing a few pads and trces did not transfer properly. I took a
> > sharpie pen and fille in the missing gap. Will the sharpie resist
> > ferric cloride or will it fail?
> >
> >
> >
> > Be sure to visit the group home and check for new Bookmarks and

> > http://groups.yahoo.com/group/Homebrew_PCBs
> > Yahoo! Groups Links
> >
> >
> >
> >
> >

> Phil wrote:
>
> > With my cross sliding vice...
>
> Any recommendations on a sliding vice that has metered action (hash
> marks on the controls for 10 mil increments or whatever)? I took

> look at what was available locally at Harbor Freight and they were

> rather large and crude, with a lot of slop. They also were too

> a Dremel drill press to have any stroke left.
>
> I imagine something made for use by jewelers would be more suitable

> a typical machine shop cross-vice.
>
> -Johnathan

--- In Homebrew_PCBs@yahoogroups.com, John Johnson <johnatl@m...> wrote:
> You know, I've been wondering why people drill holes at all.
> How about SMDIP (Surface mount DIP) instead of SMT?
> I.e. design your board so that the components mount on the
> trace side of the board. To mount DIPs, bend the legs out 90 degrees
> and solder it down like a surface mount device. You would have to adjust
> the width between the rows of pads to account for the extra width. Using
> Eagle's Offset Pads would probably do the trick. You can also surface
> mount normal, visible, passive components. Drill holes for connectors
> and things that need physical strength. You could probably do double
> sided boards like this, even with components on both sides.
> Drilling the vias, of course.
>
> Regards,
> JJ
>

> Wait a minute. Most of you guys are saying that I should drill by
> hand instead of by using the press. I thought that what the press was
> for to get more accurate drills if that is the correct word. Can you
> guys elaborate on why hand drilling is better?
>
>

--- In Homebrew_PCBs@yahoogroups.com, "Jeremy Taylor" <jt@j...> wrote:
> Sharpie will do FeCl as long as you get a good solid coat of it on
there.
> And make sure not to over etch.
>
> This next part is debatable. but IMO drilling first before etch can
lead to
> under cutting around the pad, leaving a small circle on the inside
of the
> pad that will be non conductive. this may or may not be a problem,
being
> your first board, probably wont be. as you can goop a big solder
bogey over
> the pad and all is well, - but not pretty.
>
> I personally always dill before etch, but I use a completely
different
> process, which includes, plating the holes, and using plated tin as
the etch
> resist.
>
> ----- Original Message -----
> From: "mr_gees100_peas" <geovar13@h...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Wednesday, March 24, 2004 10:01 AM
> Subject: [Homebrew_PCBs] to drill or not to dril?
>
>
> >
> > Hi I've ben reading this group for a while and I feel
confident
> > enough to make my firt PCB. I decided to use the PnP transfer
paper
> > and iron it on. Right now I manage to transfer my design to a
copper
> > bard fairly well. The thing is that I see all those holes and they
> > are so smal. I hear some people drill the holes after they etch
> > becase they can use the hole as a guide. Well, I tried driling a
few
> > holes in a practice pice of copper board nd I keep missing the
mark.
> > The board an't een etch yet but I wondering if I should drill the
> > holes fist that way I can add more resist in case I screw up.
> >
> > My second question is about sharpie pen. When I was
transfering my
> > desing a few pads and trces did not transfer properly. I took a
> > sharpie pen and fille in the missing gap. Will the sharpie resist
> > ferric cloride or will it fail?
> >
> >
> >
> > Be sure to visit the group home and check for new Bookmarks and
files:
> > http://groups.yahoo.com/group/Homebrew_PCBs
> > Yahoo! Groups Links
> >
> >
> >
> >
> >

>
> > Wait a minute. Most of you guys are saying that I should drill by
> > hand instead of by using the press. I thought that what the press

> > for to get more accurate drills if that is the correct word. Can

> > guys elaborate on why hand drilling is better?
> >
> >
>
> No, it is not better at all..
>
> Carbide drills will produce better quality holes, less burr,

> etc..
>
> But you need to align the drill tip and board exactly.
>
> with drilling by hand the hole in the copper catches the drill and

> it much easier.
> The disadvantage is you can not use carbide because it would break.
>
> If you have a press already i would use it. you have to align the

> properly,
> that is the only way then.
>
> the other two possibilities are a cnc or such a professional

> device.
> You can see them at

> the page is down.
>
> It is a "upside down" drill press. the drill comes from the bottom,

> spot on the top
> a viewing device is aimed. it has a screen and a target drawn on

> screen. you simply
> line the pad up with the target and press a switch. then a foot

> to hold the pcb
> and the drill comes up.
>
> We were thinking it must be possible to use a camera under a

> drill press for this too.
> maybe you need to use a mirror or something because the camera lens

> get full of dust.
> maybe a vac sucking the dust up is the best way.
>
> Then use a old small TV to view the picture. you can even draw

> the tv to aid in centering.
>
> It is most likely you need no foot holding the pcb here, the

> the drill helps holding it still
> while in the upside down setup it lifts it up. you also can simply

> the drill press manually.
>
>
> I guess it is a good approach if you already have a press and

> drills. such a camera is really cheap
> and a small TV is no problem i would say..
>
>
> Stefan

> Hello,
>
> THAT WAS A GREAT LINK! (Yes, I'm shouting<G>)
>
> The specific page doesn't load correctly, but most of the rest of the
> site does. Just click on something across the top... I chose products.
>
> Thank you!.
>
> Ballendo
>
> P.S. Why the tv and all that? Just use a laser pointer above, a
> dremel below, and a spring loaded table. This could be a pretty
> decent setup, IMO. Line up the laser with the dremel tool tip, and go
> to town!

> Hello,
>
> THAT WAS A GREAT LINK! (Yes, I'm shouting<G>)
>
> The specific page doesn't load correctly, but most of the rest of the
> site does. Just click on something across the top... I chose products.
>
> Thank you!.
>
> Ballendo
>
> P.S. Why the tv and all that? Just use a laser pointer above, a
> dremel below, and a spring loaded table. This could be a pretty
> decent setup, IMO. Line up the laser with the dremel tool tip, and go
> to town!

--- In Homebrew_PCBs@yahoogroups.com, JanRwl@A... wrote:

WOw, I didn't expect such a great responce to my question. It as
been a great help. Well, Last niht I decid to do a test run. I drill
a few holes with 1/32 inch dril on an unecth left over copper board.
I hit the center well close to the center with a nail to make a dent
and use tat as a guide. It turn out that with a guide the drillin was
not too far off een with my cheapo press. The problem that I
encounter is that the pads arwe not big enoght. Once the hole is
drill there is little left of the pad. I'm going to have to go back
andadd extra thickness. The thing is that I only have three PnP
sheets left . I was thinking just to add a little extra thicknes to
the pads using a sharpie but in reality I think thats doing things
half ass. Wel, Ill keep you posted on what hapens. I plan to do this
this weekend.

> The problem that I
> encounter is that the pads arwe not big enoght. Once the hole is
> drill there is little left of the pad. I'm going to have to go back
> andadd extra thickness. The thing is that I only have three PnP
> sheets left . I was thinking just to add a little extra thicknes to
> the pads using a sharpie but in reality I think thats doing things
> half ass. Wel, Ill keep you posted on what hapens. I plan to do this
> this weekend.
>

> --- In Homebrew_PCBs@yahoogroups.com, JanRwl@A... wrote:
>
> WOw, I didn't expect such a great responce to my question. It as
> been a great help. Well, Last niht I decid to do a test run. I

> a few holes with 1/32 inch dril on an unecth left over copper

> I hit the center well close to the center with a nail to make a

> and use tat as a guide. It turn out that with a guide the drillin

> not too far off een with my cheapo press. The problem that I
> encounter is that the pads arwe not big enoght. Once the hole is
> drill there is little left of the pad. I'm going to have to go back
> andadd extra thickness. The thing is that I only have three PnP
> sheets left . I was thinking just to add a little extra thicknes to
> the pads using a sharpie but in reality I think thats doing things
> half ass. Wel, Ill keep you posted on what hapens. I plan to do

> this weekend.

> along with what stefan said, it sounds like you are using too large
> drill bits. Take your components and try them in the holes. They
> should go in with out forcing. If the wires are rattling around,
> your hole is way too big. I use standard eagle library pad sizes and
> while tight, they work fairly well with the proper size bit.
>
> there's a fairly good table of bit sizes 2/3 of the way down this
> page - http://www.pacificsun.ca/~robert/pcb/pcb.htm but I'd
> encourage you to try different size on a test piece of substrate.
>

> On Fri, 26 Mar 2004 16:03:02 -0000, Phil <phil1960us@y...> wrote:
>
> > along with what stefan said, it sounds like you are using too

> > drill bits. Take your components and try them in the holes. They
> > should go in with out forcing. If the wires are rattling around,
> > your hole is way too big. I use standard eagle library pad sizes

> > while tight, they work fairly well with the proper size bit.
> >
> > there's a fairly good table of bit sizes 2/3 of the way down this
> > page - http://www.pacificsun.ca/~robert/pcb/pcb.htm but I'd
> > encourage you to try different size on a test piece of substrate.
> >
>
>
> maybe with eagle they are better....
>
> But remember the pads are also needed for mechanical stability,

> when you might have to exchange a parts too small pads will easily

> off.
>
> If there is space there is no reason why it shouldn't be taken up

> useful copper
> holding the things together.
>
> ST

> I dont disagree but once can over do it. I run traces between pads
> and would rather have the room there. Eagle libs use fairly
> elongated pads for IC leads.
>
> With a little practice, one can leave a lot of pad. In many cases,
> you have no choice. For example, double header rows - like an ICSP
> header (2x5) for programming an MCU. I put one on every project but
> there just isn't room for big ol fat pads.
>
> There is no substitute for skill/experience here.
>
> by the way, here's usefull drill conversion table
> http://www.thedirtforum.com/conversions.htm
>
> Phil

> On Fri, 26 Mar 2004 16:32:03 -0000, Phil <phil1960us@y...> wrote:
>
>
> Pads designed for throughhole plated boards just are not to be used

> plated
> boards. it is simple math, the area is too small.
>

> the 2xX headers are no problem, you could elongate them to the

> you really need.
> the problematic items are e.g. plcc throughhole sockets. because

> can't elongate
> to the side and you need to run traces between pads. But there is

> enough room to make
> it work.

> especially for a beginner there should be no problem at all finding

> for pads...

>
>
> ST
>
> (O.T. does anyone know if Maxim sends samples to individuals

> company adress?)

> --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
> <stefan_trethan@g...> wrote:
>> On Fri, 26 Mar 2004 16:32:03 -0000, Phil <phil1960us@y...> wrote:
>>
>>
>> Pads designed for throughhole plated boards just are not to be used
> in not
>> plated
>> boards. it is simple math, the area is too small.
>>
>
> hmmm, guess those last couple of boards I did shouldn't have worked.

> On Fri, 26 Mar 2004 17:54:39 -0000, Phil <phil1960us@y...> wrote:
>
> > --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
> > <stefan_trethan@g...> wrote:
> >> On Fri, 26 Mar 2004 16:32:03 -0000, Phil <phil1960us@y...> wrote:
> >>
> >>
> >> Pads designed for throughhole plated boards just are not to be

> > in not
> >> plated
> >> boards. it is simple math, the area is too small.
> >>
> >
> > hmmm, guess those last couple of boards I did shouldn't have

>
> well, if you say the pads are OK we simply disagree:
> http://www.geocities.com/phil1960us/pcb/bd2-2.jpg
>
> however these here:
> http://www.geocities.com/phil1960us/pcb/bd1-2.jpg
>
> are more what i like...
>
> I have no problem with disagreeing with you, but in the first

> the remaining ring is thinner than the track itself. that simply

> good and
> i do not think a decent soldering joint will result from it.
>
> I had similar pads to the ones you have there, years ago, until i

> them bigger
> and the overall quality did go up dramatically.
>
> You can make a working circuit by just ending the track straight,

> drilling a hole
> at the end. then you simply "glue" the part to the track. if you

> well...
>
> However i do not recommend it for a beginner already having

> hitting the center
> of the pad.
>
> It would not at all be a problem to make bigger pads on the

> have there, but
> hey, i do not want to tell you what to do... if you like it then

> it.
>
> I just want to help..
>
> Only keep in mind the difference when you have throughhole plating,

> riveted
> together, which it isn't with our boards.
>
> ST

> I dont think there is room for a wider pad in the first picture.
> when you have a 12 mil trace between pads, you can clearly see that
> there isn't much room left, maybe a couple of mils.

>
> Also, the reason I dont go straight into some of the pads is because
> I try to seperate parallel traces as much as possible to minimize
> bridging from blooming. This might be unnecessary now that my TT
> technique is much improved but old habits are hard to kick.
>
> As for lifting traces, I'm not too worried about it. If I've drilled
> the right size hole and am careful with the heat, it isn't a
> problem. Though I never have to rework my boards ... :)

----- Original Message -----
From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, March 26, 2004 1:08 PM
Subject: Re: [Homebrew_PCBs] Re: to drill or not to dril?


> On Fri, 26 Mar 2004 17:54:39 -0000, Phil <phil1960us@...> wrote:
>
> > --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
> > <stefan_trethan@g...> wrote:
> >> On Fri, 26 Mar 2004 16:32:03 -0000, Phil <phil1960us@y...> wrote:
> >>
> >>
> >> Pads designed for throughhole plated boards just are not to be used
> > in not
> >> plated
> >> boards. it is simple math, the area is too small.
> >>
> >
> > hmmm, guess those last couple of boards I did shouldn't have worked.
>
> well, if you say the pads are OK we simply disagree:
> http://www.geocities.com/phil1960us/pcb/bd2-2.jpg
>
> however these here:
> http://www.geocities.com/phil1960us/pcb/bd1-2.jpg
>
> are more what i like...
>
> I have no problem with disagreeing with you, but in the first picture
> the remaining ring is thinner than the track itself. that simply can't be
> good and
> i do not think a decent soldering joint will result from it.
>
> I had similar pads to the ones you have there, years ago, until i made
> them bigger
> and the overall quality did go up dramatically.
>
> You can make a working circuit by just ending the track straight, and
> drilling a hole
> at the end. then you simply "glue" the part to the track. if you like it,
> well...
>
> However i do not recommend it for a beginner already having problems with
> hitting the center
> of the pad.
>
> It would not at all be a problem to make bigger pads on the pictures you
> have there, but
> hey, i do not want to tell you what to do... if you like it then stay with
> it.
>
> I just want to help..
>
> Only keep in mind the difference when you have throughhole plating, it is
> riveted
> together, which it isn't with our boards.
>
> ST
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

On Fri, 26 Mar 2004 14:56:04 -0500, Jeremy Taylor <jt@...> wrote:

> A smaller hole, is NOT for PTH,
> The pad size and the hole size, are two entirely different things,
> A hole for PTH needs to be ever so slightly LARGER, to allow for the
> intended proper size, as the plating will reduce the diameter of the
> hole.
> A Small pad is intended for automated assembly machines, or for highly
> skilled workers ; | The bigger pads are nice for hobby level assembly.
>
> The only problem I see with your first link is the not so accurate
> drilling. But still very workable.
> The trace hits the pad.and can go in both directions. as long as the
> contact
> area of where the trace hits the pad is not buggered, you'll get plenty
> of
> contact.
> JT
>
> ----- Original Message -----
> From: "Stefan Trethan" <stefan_trethan@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Friday, March 26, 2004 1:08 PM
> Subject: Re: [Homebrew_PCBs] Re: to drill or not to dril?
>
>
>> On Fri, 26 Mar 2004 17:54:39 -0000, Phil <phil1960us@...> wrote:
>>
>> > --- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan
>> > <stefan_trethan@g...> wrote:
>> >> On Fri, 26 Mar 2004 16:32:03 -0000, Phil <phil1960us@y...> wrote:
>> >>
>> >>
>> >> Pads designed for throughhole plated boards just are not to be used
>> > in not
>> >> plated
>> >> boards. it is simple math, the area is too small.
>> >>
>> >
>> > hmmm, guess those last couple of boards I did shouldn't have worked.
>>
>> well, if you say the pads are OK we simply disagree:
>> http://www.geocities.com/phil1960us/pcb/bd2-2.jpg
>>
>> however these here:
>> http://www.geocities.com/phil1960us/pcb/bd1-2.jpg
>>
>> are more what i like...
>>
>> I have no problem with disagreeing with you, but in the first picture
>> the remaining ring is thinner than the track itself. that simply can't
>> be
>> good and
>> i do not think a decent soldering joint will result from it.
>>
>> I had similar pads to the ones you have there, years ago, until i made
>> them bigger
>> and the overall quality did go up dramatically.
>>
>> You can make a working circuit by just ending the track straight, and
>> drilling a hole
>> at the end. then you simply "glue" the part to the track. if you like
>> it,
>> well...
>>
>> However i do not recommend it for a beginner already having problems
>> with
>> hitting the center
>> of the pad.
>>
>> It would not at all be a problem to make bigger pads on the pictures you
>> have there, but
>> hey, i do not want to tell you what to do... if you like it then stay
>> with
>> it.
>>
>> I just want to help..
>>
>> Only keep in mind the difference when you have throughhole plating, it
>> is
>> riveted
>> together, which it isn't with our boards.
>>
>> ST
>>
>>
>>
>> Be sure to visit the group home and check for new Bookmarks and files:
>> http://groups.yahoo.com/group/Homebrew_PCBs
>> Yahoo! Groups Links
>>
>>
>>
>>
>>
>
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

> absolutely. they have one of the most generous sample policies
> going.

> > absolutely. they have one of the most generous sample policies
> > going.
>
> Oh yes! they ask for a company name (mine is Toft Technology) and

> _might_ call you, but as far as I am concerned they have the best

> policies, 8 part numbers per order, two of each! It's excellent!

> have killer parts too, I am building a NiMH battery charger using

> MAX712 part.
>
> I am not a Maxim employee, I am just _that_ impressed by their

>
> --
> Anthony Toft <toftat@c...>

> --- In Homebrew_PCBs@yahoogroups.com, Anthony Toft <toftat@c...>
> wrote:
> > > absolutely. they have one of the most generous sample policies
> > > going.
> >
> > Oh yes! they ask for a company name (mine is Toft Technology) and
> they
> > _might_ call you, but as far as I am concerned they have the best
> sample
> > policies, 8 part numbers per order, two of each! It's excellent!
> They
> > have killer parts too, I am building a NiMH battery charger using
> their
> > MAX712 part.
> >
> > I am not a Maxim employee, I am just _that_ impressed by their
> policies
> >
> > --
> > Anthony Toft <toftat@c...>
>
>
> I have requested samples from them and like their policies about
> sending them.
>
> However, I do not get samples for my personal projects unless there
> is no retail channel. Some parts are just not stocked by Digi-Key

> others.
>
> Also, I ALWAYS check the price should I ever need to buy one. A
> $22.00 ADC chip that they will send you as a sample will burn your
> wallet if you blow it up and have to replace it and cannot get
> another sample.
>
> The one thing I don't like about Maxim is that they have such darn
> small chips.
>
> A 4 amp MOSFET driver chip in an SOT-23 package. First, get white
> paper out all over the floor because if you drop it, foget finding

>
> second, the pads are on 0.9mm centers and the pads are tiny.

> that I like 1mm drills and the pad distance is less than that......
>
> And, that is a large chip as far as small chips go.
>
> I think the only way I can touch that is an toaster over solder
> project.
>
> Dave
> (who likes 8 pin DIP's)

> $# d*mn photo diode on my floor, somewhere.

----- Original Message -----
From: "Ron Amundson" <ron_amundson@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, March 27, 2004 7:24 AM
Subject: Re: [Homebrew_PCBs] Re: Maxim samples


>
> you wind up with more vias. and there is a &%
> > $# d*mn photo diode on my floor, somewhere.
>
>
> I have a white floor, for the same reason. It was not easy to find, and
the
> flooring sales guys thought I was crazy.
>
> Getting back to Maxim, they have cool parts, great samples, but when you
> only need a hundred parts or so, they are pretty tough to get. Even when I
> needed 50,000 ics, it was still hard to get a decent delivery from them.
If
> only they would handle production as easily as they handle samples.

Same here. They have a very nice dual 3.3/1,8 V regulator chip. I got a
couple of samples and then wanted to buy 20, but they wouldn't have them for
8 weeks and would only sell me a reel of 2,500. They did say eventually that
they could let me have 250 min., but that is still too much for me, even
though I found someone who would take 50 off me.

Leon

----- Original Message -----
From: "Stefan Trethan" <stefan_trethan@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Saturday, March 27, 2004 10:16 AM
Subject: Re: [Homebrew_PCBs] Re: Maxim samples


> Thanks everyone for the great response (on a tiny note).
>
>
> I placed a request a few days ago without giving them a company name.
> Will see what happens, maybe in a bit of time i place one with a company
> name
> (i will have to make one up).
>
>
> Which other companies are relatively easy with giving away samples?

TI and Analog Devices. Some distributors are very good, even if you don't
have an account with them. You might have to convince them them that you are
working on an interesting project that will use large quantiities of the
device, though.

Leon

> Same here. They have a very nice dual 3.3/1,8 V regulator chip. I got a
> couple of samples and then wanted to buy 20, but they wouldn't have them
> for
> 8 weeks and would only sell me a reel of 2,500. They did say eventually
> that
> they could let me have 250 min., but that is still too much for me, even
> though I found someone who would take 50 off me.
>
> Leon
>

>
> Hi all...
>
> I wonder why there wasn't said more about a standardized test

> to compare results..
>
> I'm still interested in one, and i will make one but
> i have hoped there is some input on what is a good pattern....
>
>
> I've bought some inkjet paper yesterday, brand is "Rex".
> It is the kind with the glossy surface, the package says "ceramic

> but
> i really doubt that a bit.
>
> I will try this one and compare to the matt paper.
>
> For a test pattern i thought about making such a "star" where you

> with
> stripes/wedges which meet at one point. i have see this on printer

> patterns.
> I guess you can make marks on the side, writing which width you are

> this radius.
> another thing will be a relatively big black area.
>
> Any ideas very welcome!
>
> ST

> Thanks everyone for the great response (on a tiny note).
>
>
> I placed a request a few days ago without giving them a company

> Will see what happens, maybe in a bit of time i place one with a

> name
> (i will have to make one up).
>
>
> Which other companies are relatively easy with giving away samples?
>
> It appears most have changed their policies, i got Philips samples
> in the past easily, but now i don't even get a answer.
>
>
> thanks
>
> ST

>
> Test pattern ?
>
> I have a simple 28 pin DIP and 28 pin SOIC with about 28 thru-holes
> that would be a good test.
>
> Make sure the holes are plated thru and could you electro-plate the
> SOIC pad in gold ?
>
> Send it to me and I'll review your test. : )
>
> Dave
>

> That is not what i meant Dave and you perfectly well know that...
>
> Really, i thought about a pattern that allows more objective

> the
> result.
> if you have these wedges you can tell at which width they merge.
>
> I tried to make such a pattern today, but didn't manage to find the

> software.
> it must be vector graphic i guess.
>
> thank you very much for you very helpful answer Dave, but i am

> looking
> for other options...
>
> ST4

>
>
> >
> > Test pattern ?
> >
> > I have a simple 28 pin DIP and 28 pin SOIC with about 28 thru-

> > that would be a good test.
> >
> > Make sure the holes are plated thru and could you electro-plate

> > SOIC pad in gold ?
> >
> > Send it to me and I'll review your test. : )
> >
> > Dave
> >

>
> Hi all...
>
> I wonder why there wasn't said more about a standardized test

> to compare results..
>
> I'm still interested in one, and i will make one but
> i have hoped there is some input on what is a good pattern....
>
>
> I've bought some inkjet paper yesterday, brand is "Rex".
> It is the kind with the glossy surface, the package says "ceramic

> but
> i really doubt that a bit.
>
> I will try this one and compare to the matt paper.
>
> For a test pattern i thought about making such a "star" where you

> with
> stripes/wedges which meet at one point. i have see this on printer

> patterns.
> I guess you can make marks on the side, writing which width you are

> this radius.
> another thing will be a relatively big black area.
>
> Any ideas very welcome!
>
> ST

>
> ----- Original Message -----
> From: "Ron Amundson" <ron_amundson@h...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Saturday, March 27, 2004 7:24 AM
> Subject: Re: [Homebrew_PCBs] Re: Maxim samples
>
>
> >
> > you wind up with more vias. and there is a &%
> > > $# d*mn photo diode on my floor, somewhere.
> >
> >
> > I have a white floor, for the same reason. It was not easy to

> the
> > flooring sales guys thought I was crazy.
> >
> > Getting back to Maxim, they have cool parts, great samples, but

> > only need a hundred parts or so, they are pretty tough to get.

> > needed 50,000 ics, it was still hard to get a decent delivery

> If
> > only they would handle production as easily as they handle

>
> Same here. They have a very nice dual 3.3/1,8 V regulator chip. I

> couple of samples and then wanted to buy 20, but they wouldn't have

> 8 weeks and would only sell me a reel of 2,500. They did say

> they could let me have 250 min., but that is still too much for me,

> though I found someone who would take 50 off me.
>
> Leon

> no problem
> I drill first with the cnc machine
> then use the ink activation, then bake the board in a convention toaster
> oven,
> Then I plate the whole board in an alkaline "flash" copper. then dry in the
> toaster oven, than a dip in hot tri sodium phosphate, a good scrub and
> rinse, then I laminate on Negative resist, and expose a positive image and
> develop, This results in everything but the traces and pads etc covered in
> resist. I then plate the tin, This plates everything exposed (including the
> holes), in very fine and solid detail, You can clearly see when everything
> is fully plated, over plating is not a problem >you do need oversized holes
> tho<. The next step is the resist stripper, then into the etch, Sulfuric
> Peroxy (which doesn't etch tin) and everything not plated with tin gets
> removed. ... I'm actually using a 10% Lead content in the tin to keep the
> tin from sprouting roots, and to "set" it, I have to reflow it, which means
> back in the oven. For boards, I plan on selling as kits (i.e.... not
> immediately assembling), I also use a nickel undercoat (between the copper
> and the tin, to prevent the anti-solderable intermetallic alloy forming)
> There are other various pre dips and post dips and rinses between each step.
> I've got it laid out in a nearly effluent free process. I can reclaim copper
> sulfate from the etch to replenish the copper plating tank. The only things
> I dispose of are the resist stripper (sodium carbonate) and the developer
> (sodium bicarbonate) which are both very safe chemicals. www.thinktink.com
> and www.caswellplating.com two US links to more info. The only "odd thing I
> had to source was the low lead tin anodes. I didn't feel 60/40 solder plate
> was very Green considering how evil Lead is. Pure tin grows metallic
> fingers that will short circuit traces, and the intermetallic alloy
> formation begins immediately, completely consuming the tin within 3 years
> (in perfect storage)
>
> JT
>
>

>I have never heard of problems of
> electroplated tin creating whiskers. Do you have any knowledge of
> tin whiskers being a concern in PCB production.
> here is an interesting articles on tin whiskers.
>

----- Original Message -----
From: "Adam Seychell" <adam_seychell@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, March 31, 2004 11:39 PM
Subject: Re: [Homebrew_PCBs] plated tin as the etch resist


>
>
> Jeremy Taylor wrote:
>
> > no problem
> > I drill first with the cnc machine
> > then use the ink activation, then bake the board in a convention toaster
> > oven,
> > Then I plate the whole board in an alkaline "flash" copper. then dry in
the
> > toaster oven, than a dip in hot tri sodium phosphate, a good scrub and
> > rinse, then I laminate on Negative resist, and expose a positive image
and
> > develop, This results in everything but the traces and pads etc covered
in
> > resist. I then plate the tin, This plates everything exposed (including
the
> > holes), in very fine and solid detail, You can clearly see when
everything
> > is fully plated, over plating is not a problem >you do need oversized
holes
> > tho<. The next step is the resist stripper, then into the etch,
Sulfuric
> > Peroxy (which doesn't etch tin) and everything not plated with tin gets
> > removed. ... I'm actually using a 10% Lead content in the tin to keep
the
> > tin from sprouting roots, and to "set" it, I have to reflow it, which
means
> > back in the oven. For boards, I plan on selling as kits (i.e.... not
> > immediately assembling), I also use a nickel undercoat (between the
copper
> > and the tin, to prevent the anti-solderable intermetallic alloy forming)
> > There are other various pre dips and post dips and rinses between each
step.
> > I've got it laid out in a nearly effluent free process. I can reclaim
copper
> > sulfate from the etch to replenish the copper plating tank. The only
things
> > I dispose of are the resist stripper (sodium carbonate) and the
developer
> > (sodium bicarbonate) which are both very safe chemicals.
www.thinktink.com
> > and www.caswellplating.com two US links to more info. The only "odd
thing I
> > had to source was the low lead tin anodes. I didn't feel 60/40 solder
plate
> > was very Green considering how evil Lead is. Pure tin grows metallic
> > fingers that will short circuit traces, and the intermetallic alloy
> > formation begins immediately, completely consuming the tin within 3
years
> > (in perfect storage)
> >
> > JT
> >
> >
>
>
> Jeremy,
> What bath compositions do you use for all three plating tanks ?
> I have done some pure tin electroplating on PTH boards and had no
> soldering problems with inter metallic alloys forming at least in
> the first month. The tin plating thickness is round 5 to 8 um
> (measured by amp hours). I have never heard of problems of
> electroplated tin creating whiskers. Do you have any knowledge of
> tin whiskers being a concern in PCB production.
> here is an interesting articles on tin whiskers.
>
http://nepp.nasa.gov/whisker/reference/tech_papers/brusse2002-slides-tin-whiskers-attributes-mitigation-CARTS-europe.pdf
>
> http://www.p-m-services.co.uk/electroless_tin.htm
>
> I seems that if plated tin is thin then the migration of copper
> in to the tin will stop the win whiskers being formed.
>
>
> The tin bath is 200/L sulfuric + 15g/L tin as stannous sulfate +
> proprietary brightener, and the copper plating bath is 200g/L
> sulfuric + 20g/L copper as copper sulfate + proprietary brightener
> .
> Is a nickel plating bath difficult to setup and maintain ?
>
>
>
>
>
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

> My tin setup is Sulfuric based, Tin stuff and Brightener
> The Tin is pattern plated at 100 milliamps per sq in (.0001 per 10 mins) I
> shoot for 0003~0004 "
> My tin Tank is 3 Gallons
>
> The Flash copper is alkaline, mostly copper sulfate with hyposodium base and
> organics.
> The copper is panel plated, with 1 amp per 10 Sq In (.00025 per 15 mins) ,
> I shoot for a 0.0005" coverage
> My copper tank is 3 Gallons
>
> The electroless Nickel is a bit complicated on keeping exact track of how
> much you have used. I know that it has Nickel in it,
> But other than that Its Part A, Part B, Part C and Water. It must be HOT
> 195 Deg F.
> Plates very evenly 0.00025" per 15 min. I shoot for .0003".
> The Nickel tank is 1/2 a gallon.
> My plating-dev-strip-etch, "system" is 32" wide X 8 feet long
>
>
>>I have never heard of problems of
>>electroplated tin creating whiskers. Do you have any knowledge of
>>tin whiskers being a concern in PCB production.
>>here is an interesting articles on tin whiskers.
>>
>
> http://nepp.nasa.gov/whisker/reference/tech_papers/brusse2002-slides-tin-whiskers-attributes-mitigation-CARTS-europe.pdf<
>
> I'm a little confuse by your statement. as the link you posted is absolutely
> a great resource on tin "whiskers" and even they end by recommending
> avoiding PURE tin. ... and that is what I've done with a 10% Lead content.
>
> I'm not going to argue the merits of intermetalic alloy formation, lots of
> factual info already out there. 1 month is not very long, ,,, 3 Year is a
> good testing point.

----- Original Message -----
From: "Adam Seychell" <adam_seychell@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, April 01, 2004 7:19 PM
Subject: Re: [Homebrew_PCBs] plated tin as the etch resist


> Jeremy,
>
> Thanks for the info,
> I assume your plating solutions (including flash plate) were
> purchased as proprietary products. so I understand why you
> wouldn't know exactly what's in the mix. As for tin plating , you
> mentioned sulfuric acid, which would mean the tin is stannous
> sulfate { also called tin(II) sulfate or SnSO4} . Is the solution
> a milky white/yellow or pale brown color ? This is normal
> color(s) for this plating bath.
>
> As for copper, I suspect you must be running a conventional acid
> copper bath to build up the copper to significant thickness. I
> understand the flash plate is primarily to get converge of copper
> inside the holes, after that, the copper is plated at high speed
> in acid copper. If you try plate too much from the
> alkaline/copper sulfate/sodium hypophosphite bath then you will
> consume too much copper and make bath maintenance difficult. I
> use carbon based method to prepare holes for electroplating in
> acid copper bath. I'm still experimenting with this.
> A good overview on method of making holes conductive is at;
> http://www.epa.gov/dfe/pubs/pwb/ctsa/ch2/ch2-1.pdf
>
>
> If your anodes are 10% lead then all I suspect this will do is
> create a excessive black film over the anodes as they are
> consumed. The reason is lead sulfate formed during dissolution of
> the anode is completely insoluble and therefore will not plate on
> the PCB. In order to plate tin/lead you need the a different type
> of chemistry. For details on tin/lead plating see:
> http://www.pfonline.com/articles/pfd0023.html
>
> I must admit I haven't tested for solderability on one of my very
> old tin plated PCBs. The oldest one is about 2 years.
> What I was saying about tin whiskers is if there has been real
> life problems with plated tin finish PCBs ? The NASA article on
> whiskers demonstrates whiskers problems on IC legs and
> connectors, but nothing on PCB's. I'm wondering if the solder
> reflow process eliminates the whisker problem since the tin is
> mixed with some lead from the solder. Very few PCBs are
> fabricated with pure tin as a final finish, but I'm curious if
> this the reason is because of the whisker problem.
>
> Adam
>
>
>
> Jeremy Taylor wrote:
> > My tin setup is Sulfuric based, Tin stuff and Brightener
> > The Tin is pattern plated at 100 milliamps per sq in (.0001 per 10 mins)
I
> > shoot for 0003~0004 "
> > My tin Tank is 3 Gallons
> >
> > The Flash copper is alkaline, mostly copper sulfate with hyposodium base
and
> > organics.
> > The copper is panel plated, with 1 amp per 10 Sq In (.00025 per 15 mins)
,
> > I shoot for a 0.0005" coverage
> > My copper tank is 3 Gallons
> >
> > The electroless Nickel is a bit complicated on keeping exact track of
how
> > much you have used. I know that it has Nickel in it,
> > But other than that Its Part A, Part B, Part C and Water. It must be
HOT
> > 195 Deg F.
> > Plates very evenly 0.00025" per 15 min. I shoot for .0003".
> > The Nickel tank is 1/2 a gallon.
> > My plating-dev-strip-etch, "system" is 32" wide X 8 feet long
> >
> >
> >>I have never heard of problems of
> >>electroplated tin creating whiskers. Do you have any knowledge of
> >>tin whiskers being a concern in PCB production.
> >>here is an interesting articles on tin whiskers.
> >>
> >
> >
http://nepp.nasa.gov/whisker/reference/tech_papers/brusse2002-slides-tin-whiskers-attributes-mitigation-CARTS-europe.pdf<
> >
> > I'm a little confuse by your statement. as the link you posted is
absolutely
> > a great resource on tin "whiskers" and even they end by recommending
> > avoiding PURE tin. ... and that is what I've done with a 10% Lead
content.
> >
> > I'm not going to argue the merits of intermetalic alloy formation, lots
of
> > factual info already out there. 1 month is not very long, ,,, 3 Year is
a
> > good testing point.
>
>
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

> This is Solderon BHT-90 series

> The surface of the plated tin does turns black in the etch, but a quick rub
> with a scotchbright cleans it up nicely

> I only plate flash copper, No acid copper - not anymore anyhow.
> It works perfectly

> Flash copper. small particle density, thus giving the kind of thru plating
> you could only get with high powered pulsed acid copper. I haven't noticed
> any increase in anode usage. as the organics keep the suspended copper in
> check. The plate actually comes from what's suspended. The anode dissolves
> as needed in to the solution. I have to keep a pump going to keep the
> copper suspended as ph fluctuates, as it's very near the point of copper
> sulfate precipitation. I use whatever is in the ink that Think and tinker
> sell, I thought it was silver based, but it's black like carbon. ... which
> makes me wonder why it costs what it does.
> I think the biggest diff noticeable for acid vs. flash - would be the
> hardness of the finish. But this is of little consequence to a pcb.
> Acid is faster. and easier to maintain. (cheaper too) but I like the flash
> much better for this application.
> I asked another group about this some time ago, and the only result I got
> was a recommendation for Electroless!
> My copper solution is green.
>
> I would probably keep the acid, If I wasn't plating tin.
>
> (whenever I use the term tin assume I mean SnPb)
>
> Yes everything I'm using is "store bought" not diy. I have about 20
> different testing solutions (Broh. Blue, Pan ind, EDTA Tet sodium, mercuric
> nitrate!! ,silver nitrate,nitric acid, etc... and related lab equipment to
> fully test all components of all solutions.) I'm really trying to keep a
> Very very low effluent.
>
> *Most pcb thru history have been SnPb, I assume Nasa was assuming this as
> well, pure Tin is pure Tin, and will do as pure tin does, no matter where it
> is. I suspect the whiskers would be more of a problem on high density
> layouts. I just err on the side of caution, as my product is a life support
> device ... for reef aquariums : )
>
> I still have my pure bright tin setup, actually expecting another on here
> soon, but I'm using it for other stuff, (emi shield on plastic housing)
>
> JT
>
>
> ----- Original Message -----
> From: "Adam Seychell" <adam_seychell@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Thursday, April 01, 2004 7:19 PM
> Subject: Re: [Homebrew_PCBs] plated tin as the etch resist
>
>
>
>>Jeremy,
>>
>>Thanks for the info,
>>I assume your plating solutions (including flash plate) were
>>purchased as proprietary products. so I understand why you
>>wouldn't know exactly what's in the mix. As for tin plating , you
>>mentioned sulfuric acid, which would mean the tin is stannous
>>sulfate { also called tin(II) sulfate or SnSO4} . Is the solution
>>a milky white/yellow or pale brown color ? This is normal
>>color(s) for this plating bath.
>>
>>As for copper, I suspect you must be running a conventional acid
>>copper bath to build up the copper to significant thickness. I
>>understand the flash plate is primarily to get converge of copper
>>inside the holes, after that, the copper is plated at high speed
>>in acid copper. If you try plate too much from the
>>alkaline/copper sulfate/sodium hypophosphite bath then you will
>>consume too much copper and make bath maintenance difficult. I
>>use carbon based method to prepare holes for electroplating in
>>acid copper bath. I'm still experimenting with this.
>>A good overview on method of making holes conductive is at;
>>http://www.epa.gov/dfe/pubs/pwb/ctsa/ch2/ch2-1.pdf
>>
>>
>>If your anodes are 10% lead then all I suspect this will do is
>>create a excessive black film over the anodes as they are
>>consumed. The reason is lead sulfate formed during dissolution of
>>the anode is completely insoluble and therefore will not plate on
>>the PCB. In order to plate tin/lead you need the a different type
>>of chemistry. For details on tin/lead plating see:
>>http://www.pfonline.com/articles/pfd0023.html
>>
>>I must admit I haven't tested for solderability on one of my very
>>old tin plated PCBs. The oldest one is about 2 years.
>>What I was saying about tin whiskers is if there has been real
>>life problems with plated tin finish PCBs ? The NASA article on
>>whiskers demonstrates whiskers problems on IC legs and
>>connectors, but nothing on PCB's. I'm wondering if the solder
>>reflow process eliminates the whisker problem since the tin is
>>mixed with some lead from the solder. Very few PCBs are
>>fabricated with pure tin as a final finish, but I'm curious if
>>this the reason is because of the whisker problem.
>>
>>Adam
>>
>>
>>
>>Jeremy Taylor wrote:
>>
>>>My tin setup is Sulfuric based, Tin stuff and Brightener
>>>The Tin is pattern plated at 100 milliamps per sq in (.0001 per 10 mins)
>
> I
>
>>>shoot for 0003~0004 "
>>>My tin Tank is 3 Gallons
>>>
>>>The Flash copper is alkaline, mostly copper sulfate with hyposodium base
>
> and
>
>>>organics.
>>>The copper is panel plated, with 1 amp per 10 Sq In (.00025 per 15 mins)
>
> ,
>
>>>I shoot for a 0.0005" coverage
>>>My copper tank is 3 Gallons
>>>
>>>The electroless Nickel is a bit complicated on keeping exact track of
>
> how
>
>>>much you have used. I know that it has Nickel in it,
>>>But other than that Its Part A, Part B, Part C and Water. It must be
>
> HOT
>
>>>195 Deg F.
>>>Plates very evenly 0.00025" per 15 min. I shoot for .0003".
>>>The Nickel tank is 1/2 a gallon.
>>>My plating-dev-strip-etch, "system" is 32" wide X 8 feet long
>>>
>>>
>>>
>>>>I have never heard of problems of
>>>>electroplated tin creating whiskers. Do you have any knowledge of
>>>>tin whiskers being a concern in PCB production.
>>>>here is an interesting articles on tin whiskers.
>>>>
>>>
>>>
> http://nepp.nasa.gov/whisker/reference/tech_papers/brusse2002-slides-tin-whiskers-attributes-mitigation-CARTS-europe.pdf<
>
>>>I'm a little confuse by your statement. as the link you posted is
>
> absolutely
>
>>>a great resource on tin "whiskers" and even they end by recommending
>>>avoiding PURE tin. ... and that is what I've done with a 10% Lead
>
> content.
>
>>>I'm not going to argue the merits of intermetalic alloy formation, lots
>
> of
>
>>>factual info already out there. 1 month is not very long, ,,, 3 Year is
>
> a
>
>>>good testing point.
>>
>>
>>
>>
>>
>>Be sure to visit the group home and check for new Bookmarks and files:
>>http://groups.yahoo.com/group/Homebrew_PCBs
>>Yahoo! Groups Links
>>
>>
>>
>>
>>
>
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

----- Original Message -----
From: "Jeremy Taylor" <jt@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, April 01, 2004 9:01 PM
Subject: Re: [Homebrew_PCBs] plated tin as the etch resist


> My chemistry is for Tin/Lead (it' all about the organics, which I called
> brightener thinking of Bright tin which my kit was originally purchased
as)
> This is Solderon BHT-90 series I could buy the separated Tin con, Pb
> con,Anti foam , and carrier but they offered me a small pre mix to try it
> out. (RohmHaas directly) I'll be buying the components in the future. My
> solution is yellow.
> The surface of the plated tin does turns black in the etch, but a quick
rub
> with a scotchbright cleans it up nicely
>
> I only plate flash copper, No acid copper - not anymore anyhow.
> It works perfectly
> Flash copper. small particle density, thus giving the kind of thru
plating
> you could only get with high powered pulsed acid copper. I haven't noticed
> any increase in anode usage. as the organics keep the suspended copper in
> check. The plate actually comes from what's suspended. The anode dissolves
> as needed in to the solution. I have to keep a pump going to keep the
> copper suspended as ph fluctuates, as it's very near the point of copper
> sulfate precipitation. I use whatever is in the ink that Think and tinker
> sell, I thought it was silver based, but it's black like carbon. ... which
> makes me wonder why it costs what it does.
> I think the biggest diff noticeable for acid vs. flash - would be the
> hardness of the finish. But this is of little consequence to a pcb.
> Acid is faster. and easier to maintain. (cheaper too) but I like the flash
> much better for this application.
> I asked another group about this some time ago, and the only result I got
> was a recommendation for Electroless!
> My copper solution is green.
>
> I would probably keep the acid, If I wasn't plating tin.
>
> (whenever I use the term tin assume I mean SnPb)
>
> Yes everything I'm using is "store bought" not diy. I have about 20
> different testing solutions (Broh. Blue, Pan ind, EDTA Tet sodium,
mercuric
> nitrate!! ,silver nitrate,nitric acid, etc... and related lab equipment to
> fully test all components of all solutions.) I'm really trying to keep a
> Very very low effluent.
>
> *Most pcb thru history have been SnPb, I assume Nasa was assuming this as
> well, pure Tin is pure Tin, and will do as pure tin does, no matter where
it
> is. I suspect the whiskers would be more of a problem on high density
> layouts. I just err on the side of caution, as my product is a life
support
> device ... for reef aquariums : )
>
> I still have my pure bright tin setup, actually expecting another on here
> soon, but I'm using it for other stuff, (emi shield on plastic housing)
>
> JT
>
>
> ----- Original Message -----
> From: "Adam Seychell" <adam_seychell@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Thursday, April 01, 2004 7:19 PM
> Subject: Re: [Homebrew_PCBs] plated tin as the etch resist
>
>
> > Jeremy,
> >
> > Thanks for the info,
> > I assume your plating solutions (including flash plate) were
> > purchased as proprietary products. so I understand why you
> > wouldn't know exactly what's in the mix. As for tin plating , you
> > mentioned sulfuric acid, which would mean the tin is stannous
> > sulfate { also called tin(II) sulfate or SnSO4} . Is the solution
> > a milky white/yellow or pale brown color ? This is normal
> > color(s) for this plating bath.
> >
> > As for copper, I suspect you must be running a conventional acid
> > copper bath to build up the copper to significant thickness. I
> > understand the flash plate is primarily to get converge of copper
> > inside the holes, after that, the copper is plated at high speed
> > in acid copper. If you try plate too much from the
> > alkaline/copper sulfate/sodium hypophosphite bath then you will
> > consume too much copper and make bath maintenance difficult. I
> > use carbon based method to prepare holes for electroplating in
> > acid copper bath. I'm still experimenting with this.
> > A good overview on method of making holes conductive is at;
> > http://www.epa.gov/dfe/pubs/pwb/ctsa/ch2/ch2-1.pdf
> >
> >
> > If your anodes are 10% lead then all I suspect this will do is
> > create a excessive black film over the anodes as they are
> > consumed. The reason is lead sulfate formed during dissolution of
> > the anode is completely insoluble and therefore will not plate on
> > the PCB. In order to plate tin/lead you need the a different type
> > of chemistry. For details on tin/lead plating see:
> > http://www.pfonline.com/articles/pfd0023.html
> >
> > I must admit I haven't tested for solderability on one of my very
> > old tin plated PCBs. The oldest one is about 2 years.
> > What I was saying about tin whiskers is if there has been real
> > life problems with plated tin finish PCBs ? The NASA article on
> > whiskers demonstrates whiskers problems on IC legs and
> > connectors, but nothing on PCB's. I'm wondering if the solder
> > reflow process eliminates the whisker problem since the tin is
> > mixed with some lead from the solder. Very few PCBs are
> > fabricated with pure tin as a final finish, but I'm curious if
> > this the reason is because of the whisker problem.
> >
> > Adam
> >
> >
> >
> > Jeremy Taylor wrote:
> > > My tin setup is Sulfuric based, Tin stuff and Brightener
> > > The Tin is pattern plated at 100 milliamps per sq in (.0001 per 10
mins)
> I
> > > shoot for 0003~0004 "
> > > My tin Tank is 3 Gallons
> > >
> > > The Flash copper is alkaline, mostly copper sulfate with hyposodium
base
> and
> > > organics.
> > > The copper is panel plated, with 1 amp per 10 Sq In (.00025 per 15
mins)
> ,
> > > I shoot for a 0.0005" coverage
> > > My copper tank is 3 Gallons
> > >
> > > The electroless Nickel is a bit complicated on keeping exact track of
> how
> > > much you have used. I know that it has Nickel in it,
> > > But other than that Its Part A, Part B, Part C and Water. It must be
> HOT
> > > 195 Deg F.
> > > Plates very evenly 0.00025" per 15 min. I shoot for .0003".
> > > The Nickel tank is 1/2 a gallon.
> > > My plating-dev-strip-etch, "system" is 32" wide X 8 feet long
> > >
> > >
> > >>I have never heard of problems of
> > >>electroplated tin creating whiskers. Do you have any knowledge of
> > >>tin whiskers being a concern in PCB production.
> > >>here is an interesting articles on tin whiskers.
> > >>
> > >
> > >
>
http://nepp.nasa.gov/whisker/reference/tech_papers/brusse2002-slides-tin-whiskers-attributes-mitigation-CARTS-europe.pdf<
> > >
> > > I'm a little confuse by your statement. as the link you posted is
> absolutely
> > > a great resource on tin "whiskers" and even they end by recommending
> > > avoiding PURE tin. ... and that is what I've done with a 10% Lead
> content.
> > >
> > > I'm not going to argue the merits of intermetalic alloy formation,
lots
> of
> > > factual info already out there. 1 month is not very long, ,,, 3 Year
is
> a
> > > good testing point.
> >
> >
> >
> >
> >
> > Be sure to visit the group home and check for new Bookmarks and files:
> > http://groups.yahoo.com/group/Homebrew_PCBs
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

> My chemistry is for Tin/Lead (it' all about the organics, which I called
> brightener thinking of Bright tin which my kit was originally

> This is Solderon BHT-90 series I could buy the separated Tin con, Pb
> con,Anti foam , and carrier but they offered me a small pre mix to

> out. (RohmHaas directly) I'll be buying the components in the future. My
> solution is yellow.
> The surface of the plated tin does turns black in the etch, but a

> with a scotchbright cleans it up nicely
>

----- Original Message -----
From: "Adam Seychell" <adam_seychell@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, April 01, 2004 9:53 PM
Subject: Re: [Homebrew_PCBs] plated tin as the etch resist


>
>
> Jeremy Taylor wrote:
>
> > This is Solderon BHT-90 series
>
> Ok, that clears up the confusion. If you say it contains sulfuric
> but can also plate tin/lead so then the it must have some other
> electrolytes for solubility of Pb.
>

> If you dip the tin-lead plated panels in straight peroxide (30% or
> stronger) for 15 or 20 seconds
> Tom

> My last post must been sent just prior to yours.
>
> I actually ended up completely closing up some holes with the acid copper.

> It' definitely a more aggressive plate.

----- Original Message -----
From: "Adam Seychell" <adam_seychell@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Thursday, April 01, 2004 11:09 PM
Subject: Re: [Homebrew_PCBs] plated tin as the etch resist


>
>
> Jeremy Taylor wrote:
> > My last post must been sent just prior to yours.
> >
> > I actually ended up completely closing up some holes with the acid
copper.
>
> Does that mean the alkaline plate was more capable of completely
> covering the holes walls with copper than compared to acid copper
> plating ? Which bath was better ?
>
>
> > It' definitely a more aggressive plate.
>
> yes, the acid copper is fast, almost 100% coulombetric
> efficient, good throwing power and easy to maintain and setup.
> This is why I suspect you have chosen alkaline plating because it
> performed better when plating on the ink surface.
>
> Regards,
>
> Adam
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

> however, they did not obey my wishes concerning the packages in most cases.
> (i was bold enough selecting cerdip but got only pdip)

>
>
> Jeremy Taylor wrote:
> > My last post must been sent just prior to yours.
> >
> > I actually ended up completely closing up some holes with the

>
> Does that mean the alkaline plate was more capable of completely
> covering the holes walls with copper than compared to acid copper
> plating ? Which bath was better ?
>
>
> > It' definitely a more aggressive plate.
>
> yes, the acid copper is fast, almost 100% coulombetric
> efficient, good throwing power and easy to maintain and setup.
> This is why I suspect you have chosen alkaline plating because it
> performed better when plating on the ink surface.
>
> Regards,
>
> Adam

> Hard to say - and subjective at best. but IMO yes.
> We can discuss this more tomorrow, I've been trying to take some pics , but
> man is it difficult to even get the holes...







>
>
>
> http://www.soundclick.com/jtsound
> ----- Original Message -----
> From: "Adam Seychell" <adam_seychell@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Thursday, April 01, 2004 11:09 PM
> Subject: Re: [Homebrew_PCBs] plated tin as the etch resist
>
>
>
>>
>>Jeremy Taylor wrote:
>>
>>>My last post must been sent just prior to yours.
>>>
>>>I actually ended up completely closing up some holes with the acid
>
> copper.
>
>>Does that mean the alkaline plate was more capable of completely
>>covering the holes walls with copper than compared to acid copper
>>plating ? Which bath was better ?
>>
>>
>>
>>>It' definitely a more aggressive plate.
>>
>>yes, the acid copper is fast, almost 100% coulombetric
>>efficient, good throwing power and easy to maintain and setup.
>>This is why I suspect you have chosen alkaline plating because it
>>performed better when plating on the ink surface.
>>
>>Regards,
>>
>>Adam
>>
>>
>>
>>Be sure to visit the group home and check for new Bookmarks and files:
>>http://groups.yahoo.com/group/Homebrew_PCBs
>>Yahoo! Groups Links
>>
>>
>>
>>
>>
>
>
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

----- Original Message -----
From: "Adam Seychell" <adam_seychell@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, April 02, 2004 6:36 PM
Subject: Re: [Homebrew_PCBs] Plating Holes (was: plated tin as the etch
resist)


>
> Ok, thanks for your response. I thought you might have had made a grand
> discovery in getting through holes to place reliably over carbon coated
> holes. As I said earlier, I'm using carbon black to coat the holes and I
am
> experiencing the same problems as many did in who tried to make
> carbon/graphite process commercially viable, such as MacDermid. The
current
> process by MacDermid is called BLACKHOLE SP, and is well established in
> industry. They claim BLACKHOLE SP to be suitable for even the most high
> tech PCBs, 16+ layers, 0.1 mm hole diameters, et. The early attempts by
> these companies had problems getting the copper to plate on relatively
thin
> layer of carbon/graphite. From my experiments of plating carbon coated
> holes, I've found the chemistry of the plating solution to play a huge
part
> in obtaining successful copper coverage. For example, I found acid sulfate
> bright tin bath plates the holes much more reliable than acid copper bath.
> I also found small amounts of chloride in the acid copper bath have a
> detrimental effect, with > 300ppm of Cl- will completely inhibit any hole
> wall plating. I am wondering if the alkaline bath you use is the answer to
> getting the holes plated with good reliability. I'm not up to speed with
my
> electrochemistry but I believe the reason holes are difficult to plate in
> is that the carbon has a higher overpotential for deposition of copper
than
> copper on copper does. In other words you need higher cell voltage to
plate
> on carbon than on copper. Overpotentials depend on many things and pH is
> one of them. The carbon surface resistively is relatively high (about
10e+6
> times more resistance of a unit square) compared to the copper foil
surface
> resistively. During plating a voltage drop develops at the boundary were
> copper meets the carbon. The result is a forward growth of copper over the
> carbon surface during the plating cycle. The copper growth emanates at the
> hole ends and eventually meets half way inside the hole completing the
> coverage. Its the rate of this copper growth front the determines how good
> the process is running. If the growth rate is too slow (or nonexistent)
> then too much copper will be deposited on copper cladding, and not enough
> inside the holes. Worse still is the voiding inside the holes due to
> patches of extremely thin coatings of carbon. This is the fundamental
problem.
>
> There a number of alkaline copper plating chemistries that could be
tested.
> The good news is we don't need high speed, smooth bright finishes, since
> the aim is to "flash plate". The acid copper bath will take care of the
> remaining copper. Industrial alkaline copper uses cyanide , which I prefer
> not to use. Another possibility is copper sulfate + ammonia hydroxide +
> ammonium sulfate with around pH 8 so it doesn't smell.
>
> Like you, I am doing this as a hobby so I don't get the time needed to do
> thorough experiments. I did most of my carbon hole work when I had a part
> time job in which I had the time to built a home lab just to explore this
> process. I've had a about 1 year break from it now, but these discussions
> have got me thinking about it again. It might be time to dust out the lab.
>
> Adam
>
>
>
>
> Jeremy Taylor wrote:
> > Hard to say - and subjective at best. but IMO yes.
> > We can discuss this more tomorrow, I've been trying to take some pics ,
but
> > man is it difficult to even get the holes...
>
>
>
>
>
>
>
> >
> >
> >
> > http://www.soundclick.com/jtsound
> > ----- Original Message -----
> > From: "Adam Seychell" <adam_seychell@...>
> > To: <Homebrew_PCBs@yahoogroups.com>
> > Sent: Thursday, April 01, 2004 11:09 PM
> > Subject: Re: [Homebrew_PCBs] plated tin as the etch resist
> >
> >
> >
> >>
> >>Jeremy Taylor wrote:
> >>
> >>>My last post must been sent just prior to yours.
> >>>
> >>>I actually ended up completely closing up some holes with the acid
> >
> > copper.
> >
> >>Does that mean the alkaline plate was more capable of completely
> >>covering the holes walls with copper than compared to acid copper
> >>plating ? Which bath was better ?
> >>
> >>
> >>
> >>>It' definitely a more aggressive plate.
> >>
> >>yes, the acid copper is fast, almost 100% coulombetric
> >>efficient, good throwing power and easy to maintain and setup.
> >>This is why I suspect you have chosen alkaline plating because it
> >>performed better when plating on the ink surface.
> >>
> >>Regards,
> >>
> >>Adam
> >>
> >>
> >>
> >>Be sure to visit the group home and check for new Bookmarks and files:
> >>http://groups.yahoo.com/group/Homebrew_PCBs
> >>Yahoo! Groups Links
> >>
> >>
> >>
> >>
> >>
> >
> >
> >
> >
> >
> > Be sure to visit the group home and check for new Bookmarks and files:
> > http://groups.yahoo.com/group/Homebrew_PCBs
> > Yahoo! Groups Links
> >
> >
> >
> >
> >
>
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>

> I think it really has to do with the balancing chemistries. , or the
> organics. The Flash I'm using has no cyanide, I was under the impression
> that the blackhole method was purley an electroless process , including the
> copper flash.
>
> ** Big side note here ... I'm not a chemist, and I cant get in to many
> details beyond the basics, or what I have specific instructions for.
> I was under the impresion that the balncers were most attracted to the areas
> with the greates potential for conductivity. And thus the higher thier
> consentration in the solution, the more profound the hole plating vs the
> foil~ would be. as the foil surface en mass is of higher potential. I have
> noted that I start to see color change in the holes before the foil begins
> to pinken. < is that a word? So I'm assumin I happen to have enough organic
> content to effectivley hamper the plating on the urface of the foil until
> after the hole walls bein to fall in to balance with the foil surface.
> I've also seen that I do not need to flip and rotate the board 1/2 thru
> plating for uniformity like I did with the acid copper. But this may be due
> to anode placement. vs board size, so to many variable to state that as
> fact. Caswell sataes it like this:
>
> "
> FLASH COPPER produces a fine grained. smooth. dense and ductile copper
> deposit. which is nonporus and has excellent bonding properties. The
> throwing and covering power of the non-cyanide process is superior to
> cyanide processes. This is especially evident in barrel plating. It has
> uniform low current density distribution with excellent micro-throw
> The grain is smaller than cyanide copper. which increases the density of the
> deposit. This density provides excellent heat treat stop off and masking
> properties. The fine-grained FLASH COPPER deposit under nickel chrome
> improves the overall corrosion resistance and helps to throw the nickel
> farther into the low current density areas.
> FLASH COPPER produces a softer and more ductile deposit than cyanide or acid
> copper. The soft deposit imparts improved adhesion and corrosion resistance
> and greatly improved resistance to thermal shock.
> It has a high deposit purity and hence no out-gassing with subsequeut
> brazing. soldering or vacuum operations.
> FLASH COPPER is simple and inexpensive to use because it replenishes the
> copper in solution by dissolving the copper anode and here again it is a
> unique product with only one maintenance additive.
> "
>
>
> After speaking with Ron at TnT , he sugested that alot of customers who use
> thier process skip the flash step, and go directly to pattern plating with
> thier Acid copper product, I'd asume they have acid worked out well enough
> to market it with the ink , or we'd be seeing a change in procedure. But
> with that siad, Caswells flash is performing very well and for a complete
> kit setup cost under $200 I'd like to see more people try this method to
> verify my results. Caswell sells a product called "silvaspray" made for
> plating plastics and works very well with the flash copper product, I'd
> suspect - it to could be used for hole plating. I'll probably try it out
> when I start running out of the TnT ink.
>
> ... thoughts to promote either a solid tin / SnPb plate, or acid copper
> plate over the flash. I'm tempted to try a few boards without eitther to see
> if it holds up , If the solder from the assembly process would cover it. I'm
> preparing a plot for a negative I'll run tonigh, In the morning I'll see how
> it deveolps, and if this film can tent well enough I'll give it a go
>
> JT
>
>
> ----- Original Message -----
> From: "Adam Seychell" <adam_seychell@...>
> To: <Homebrew_PCBs@yahoogroups.com>
> Sent: Friday, April 02, 2004 6:36 PM
> Subject: Re: [Homebrew_PCBs] Plating Holes (was: plated tin as the etch
> resist)
>
>
>
>>Ok, thanks for your response. I thought you might have had made a grand
>>discovery in getting through holes to place reliably over carbon coated
>>holes. As I said earlier, I'm using carbon black to coat the holes and I
>
> am
>
>>experiencing the same problems as many did in who tried to make
>>carbon/graphite process commercially viable, such as MacDermid. The
>
> current
>
>>process by MacDermid is called BLACKHOLE SP, and is well established in
>>industry. They claim BLACKHOLE SP to be suitable for even the most high
>>tech PCBs, 16+ layers, 0.1 mm hole diameters, et. The early attempts by
>>these companies had problems getting the copper to plate on relatively
>
> thin
>
>>layer of carbon/graphite. From my experiments of plating carbon coated
>>holes, I've found the chemistry of the plating solution to play a huge
>
> part
>
>>in obtaining successful copper coverage. For example, I found acid sulfate
>>bright tin bath plates the holes much more reliable than acid copper bath.
>>I also found small amounts of chloride in the acid copper bath have a
>>detrimental effect, with > 300ppm of Cl- will completely inhibit any hole
>>wall plating. I am wondering if the alkaline bath you use is the answer to
>>getting the holes plated with good reliability. I'm not up to speed with
>
> my
>
>>electrochemistry but I believe the reason holes are difficult to plate in
>>is that the carbon has a higher overpotential for deposition of copper
>
> than
>
>>copper on copper does. In other words you need higher cell voltage to
>
> plate
>
>>on carbon than on copper. Overpotentials depend on many things and pH is
>>one of them. The carbon surface resistively is relatively high (about
>
> 10e+6
>
>>times more resistance of a unit square) compared to the copper foil
>
> surface
>
>>resistively. During plating a voltage drop develops at the boundary were
>>copper meets the carbon. The result is a forward growth of copper over the
>>carbon surface during the plating cycle. The copper growth emanates at the
>>hole ends and eventually meets half way inside the hole completing the
>>coverage. Its the rate of this copper growth front the determines how good
>>the process is running. If the growth rate is too slow (or nonexistent)
>>then too much copper will be deposited on copper cladding, and not enough
>>inside the holes. Worse still is the voiding inside the holes due to
>>patches of extremely thin coatings of carbon. This is the fundamental
>
> problem.
>
>>There a number of alkaline copper plating chemistries that could be
>
> tested.
>
>>The good news is we don't need high speed, smooth bright finishes, since
>>the aim is to "flash plate". The acid copper bath will take care of the
>>remaining copper. Industrial alkaline copper uses cyanide , which I prefer
>>not to use. Another possibility is copper sulfate + ammonia hydroxide +
>>ammonium sulfate with around pH 8 so it doesn't smell.
>>
>>Like you, I am doing this as a hobby so I don't get the time needed to do
>>thorough experiments. I did most of my carbon hole work when I had a part
>>time job in which I had the time to built a home lab just to explore this
>>process. I've had a about 1 year break from it now, but these discussions
>>have got me thinking about it again. It might be time to dust out the lab.
>>
>>Adam
>>
>>
>>
>>
>>Jeremy Taylor wrote:
>>
>>>Hard to say - and subjective at best. but IMO yes.
>>>We can discuss this more tomorrow, I've been trying to take some pics ,
>
> but
>
>>>man is it difficult to even get the holes...
>>
>>
>>
>>
>>
>>
>>
>>>
>>>
>>>http://www.soundclick.com/jtsound
>>>----- Original Message -----
>>>From: "Adam Seychell" <adam_seychell@...>
>>>To: <Homebrew_PCBs@yahoogroups.com>
>>>Sent: Thursday, April 01, 2004 11:09 PM
>>>Subject: Re: [Homebrew_PCBs] plated tin as the etch resist
>>>
>>>
>>>
>>>
>>>>Jeremy Taylor wrote:
>>>>
>>>>
>>>>>My last post must been sent just prior to yours.
>>>>>
>>>>>I actually ended up completely closing up some holes with the acid
>>>
>>>copper.
>>>
>>>
>>>>Does that mean the alkaline plate was more capable of completely
>>>>covering the holes walls with copper than compared to acid copper
>>>>plating ? Which bath was better ?
>>>>
>>>>
>>>>
>>>>
>>>>>It' definitely a more aggressive plate.
>>>>
>>>>yes, the acid copper is fast, almost 100% coulombetric
>>>>efficient, good throwing power and easy to maintain and setup.
>>>>This is why I suspect you have chosen alkaline plating because it
>>>>performed better when plating on the ink surface.
>>>>
>>>>Regards,
>>>>
>>>>Adam
>>>>
>>>>
>>>>
>>>>Be sure to visit the group home and check for new Bookmarks and files:
>>>>http://groups.yahoo.com/group/Homebrew_PCBs
>>>>Yahoo! Groups Links
>>>>
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>>Be sure to visit the group home and check for new Bookmarks and files:
>>>http://groups.yahoo.com/group/Homebrew_PCBs
>>>Yahoo! Groups Links
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>>
>>Be sure to visit the group home and check for new Bookmarks and files:
>>http://groups.yahoo.com/group/Homebrew_PCBs
>>Yahoo! Groups Links
>>
>>
>>
>>
>>
>
>
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
> http://groups.yahoo.com/group/Homebrew_PCBs
> Yahoo! Groups Links
>
>
>
>
>