Homebrew_PCBs

On 3/18/2016 10:36 PM, 'Brad' unclefalter@... [Homebrew_PCBs] wrote:

> <snip>

> I’m wondering – what differs in etching with double sided projects?
> And when they say the holes weren’t plated through, does it mean what
> I think it means (there would be a copper connection between a trace
> on one side through a hole the component is soldered into through to
> the other side?). Not sure I’m understanding how the connections
> would be made from one side to the other.
>

Hello--

One process used in the 1970s involved drilling holes through a
double-sided copperclad board, followed by an
electroplating process that deposited copper on the insides of the
holes. The board was then coated with resist,
exposed, developed and etched. Removal of the remaining resist exposed
the plated-through holes (vias)
for component insertion. (I've omitted several intermediate steps for
brevity.)

Homemade double-sided boards rely on using components' leads as the
vias, but you need to solder the components'
leads on both sides of the board to ensure continuity.

73--

Brad AA1IP

Brad,

You are correct, this is quite a challenging project.

Plated through holes:

If you look at the board artwork in the article, you will find a view where they show the overlap between top and bottom patterns. At every location where the pads on the top and bottom have traces attached, there needs to be a connection between the top layer and the bottom layer.  A board with plated through holes has a lining of copper plated into the holes to make those connections.  Where there are no plated holes, the connection can be made by one of several methods.  The easiest is to use the wires that go through the holes. For example, where a resistor or IC lead is in the hole, it would need to be soldered both top and bottom.  For holes that just make a connection from the top to the bottom, a wire can be placed in the hole and soldered top and bottom.  I usually make a small stub that is bent over at the end of the wire.  I drop it into the hole and solder.  Then I bend the wire the opposite way on the other side, and solder.   This is called a "z" wire.  Plated through holes are the best way to go, but are difficult to do in the home lab. 

There are several complications associated with making two sided boards. The first, and most obvious, is that the two patterns have to be very closely aligned.  This is  required because of the connections between the two sizes. The holes must be drilled such that they pass through the pads on both sides.  The actual etching process is also fraught with problems.  You can choose to etch both sides at the same time, or protect one side from the etchant while etching the first side. Then reverse the procedure by protecting the first side and etching the second.  The second process is tedious, but may result in better boards.  It is hard to get both sides to etch evenly, and I frequently would wind up with over etching on one side when I tried to etch both at the same time.  This is especially true with large boards such as the ones in this project.

(Another Harvey)

 

Separate discussion.

 

I’m not planning to tackle this anytime soon, but I have been slowly acquiring parts and am hoping after I’ve gained lots of experience to one day build a Mark-8 replica.

 

I expect this would be a very challenging project, which is why it’s long in the future.  But I’m always interested, always reading and learning.

 

Jon Titus, the creator, arranged with a New Jersey company to produce board sets hobbyists could order, similar to the TVT.  Those obviously are ultra rare unobtanium now, however, I’m guessing the presence of circuit board patterns in the construction details (http://bytecollector.com/archive/mark_8/My_Mark-8_Info/Mark-8_Construction/RE_Mark-8_Const-NEW.pdf -- page 25 or so) indicates it was at least possible some hobbyists went and made their own, correct?

 

I’m wondering – what differs in etching with double sided projects?  And when they say the holes weren’t plated through, does it mean what I think it means (there would be a copper connection between a trace on one side through a hole the component is soldered into through to the other side?).  Not sure I’m understanding how the connections would be made from one side to the other.

On Fri, 18 Mar 2016 20:21:11 -0700, you wrote:

>Brad,
>
>You are correct, this is quite a challenging project.
>
>Plated through holes:
>
>If you look at the board artwork in the article, you will find a view
>where they show the overlap between top and bottom patterns. At every
>location where the pads on the top and bottom have traces attached,
>there needs to be a connection between the top layer and the bottom
>layer. A board with plated through holes has a lining of copper plated
>into the holes to make those connections. Where there are no plated
>holes, the connection can be made by one of several methods. The
>easiest is to use the wires that go through the holes. For example,
>where a resistor or IC lead is in the hole, it would need to be soldered
>both top and bottom. For holes that just make a connection from the top
>to the bottom, a wire can be placed in the hole and soldered top and
>bottom. I usually make a small stub that is bent over at the end of the
>wire. I drop it into the hole and solder. Then I bend the wire the
>opposite way on the other side, and solder. This is called a "z"
>wire. Plated through holes are the best way to go, but are difficult to
>do in the home lab.

You can use eyelets, however, those are quite large in comparison, and
you need a source for them, and a staking tool.

>
>There are several complications associated with making two sided boards.
>The first, and most obvious, is that the two patterns have to be very
>closely aligned. This is required because of the connections between
>the two sizes. The holes must be drilled such that they pass through the
>pads on both sides. The actual etching process is also fraught with
>problems. You can choose to etch both sides at the same time, or
>protect one side from the etchant while etching the first side. Then
>reverse the procedure by protecting the first side and etching the
>second. The second process is tedious, but may result in better
>boards. It is hard to get both sides to etch evenly, and I frequently
>would wind up with over etching on one side when I tried to etch both at
>the same time. This is especially true with large boards such as the
>ones in this project.

I have tried both approaches, protecting a board side (you use
transparent contact paper), or not (you hope that it works well as you
have noted.)

However, I've done several things that seem to work well in
combination.

1) toner transfer top and bottom on two thinner boards. The material
I have is 0.021 or so and single sided, so that is good.

2) etch as needed.

3) drill the alignment holes *very* precisely. You'd like them within
about 0.002 of where they should be. I think I can get that close. I
can get rather thin vias to line up properly when using a #78 drill
(IIRC), using 10/10 for the process. I use #26 wire wrap wire,
stripped, for lacing the vias together.

However, I put a coating of long setting epoxy (about 1 hour work
time) on the boards. Cover the entire outside surface of the board
with masking tape, (keeps fingerprints off the copper), align the
boards with relatively thick pins, tape them so they cannot move, then
put them between two floor tiles to hold them flat while the epoxy
cures.

You get some well aligned boards that way, and if you screw up a
board, you only mess up one side.

Harvey

>
>(Another Harvey)
>
>
>On 3/18/2016 7:36 PM, 'Brad' unclefalter@... [Homebrew_PCBs] wrote:
>>
>> Separate discussion.
>>
>> I’m not planning to tackle this anytime soon, but I have been slowly
>> acquiring parts and am hoping after I’ve gained lots of experience to
>> one day build a Mark-8 replica.
>>
>> I expect this would be a very challenging project, which is why it’s
>> long in the future. But I’m always interested, always reading and
>> learning.
>>
>> Jon Titus, the creator, arranged with a New Jersey company to produce
>> board sets hobbyists could order, similar to the TVT. Those obviously
>> are ultra rare unobtanium now, however, I’m guessing the presence of
>> circuit board patterns in the construction details
>> (http://bytecollector.com/archive/mark_8/My_Mark-8_Info/Mark-8_Construction/RE_Mark-8_Const-NEW.pdf
>> -- page 25 or so) indicates it was at least possible some hobbyists
>> went and made their own, correct?
>>
>> I’m wondering – what differs in etching with double sided projects?
>> And when they say the holes weren’t plated through, does it mean what
>> I think it means (there would be a copper connection between a trace
>> on one side through a hole the component is soldered into through to
>> the other side?). Not sure I’m understanding how the connections
>> would be made from one side to the other.
>>
>>

On Fri, 18 Mar 2016 19:36:14 -0700, you wrote:

>Separate discussion.
>
>
>
>I’m not planning to tackle this anytime soon, but I have been slowly acquiring parts and am hoping after I’ve gained lots of experience to one day build a Mark-8 replica.
>
>
>
>I expect this would be a very challenging project, which is why it’s long in the future. But I’m always interested, always reading and learning.
>
>
>
>Jon Titus, the creator, arranged with a New Jersey company to produce board sets hobbyists could order, similar to the TVT. Those obviously are ultra rare unobtanium now, however, I’m guessing the presence of circuit board patterns in the construction details (http://bytecollector.com/archive/mark_8/My_Mark-8_Info/Mark-8_Construction/RE_Mark-8_Const-NEW.pdf -- page 25 or so) indicates it was at least possible some hobbyists went and made their own, correct?
>
>
>
>I’m wondering – what differs in etching with double sided projects? And when they say the holes weren’t plated through, does it mean what I think it means (there would be a copper connection between a trace on one side through a hole the component is soldered into through to the other side?). Not sure I’m understanding how the connections would be made from one side to the other.

Alignment between top and bottom is critical. The spacing between
lines and the size of the lines themselves is often given by two
numbers (in mills) 10/10 meaning .010 thick lines with a minimum
spacing of 0.010 inches.

Plated through holes are a normal part of double sided boards, and the
plating is also used to connect inner layers on multilayer boards. The
main problem with plated through holes in the home environment is a
combination of the number of steps needed, the unpleasantness of the
chemicals, the cost of the same, and the shelf life.

while it can add an hour or two depending on the complexity of the
board, the eyelet or the laced wire method is one solution to the
problem. Commercial conductive ink solutions may or may not be a good
idea depending. Never tried them myself.

I've done home built boards that are good enough to handle 100 pin 0.5
mm spacing quad flatpacks, although they are a pain to do and not
always a certainty that they will be done properly.

For some boards, I find that I needed to go finer and pack more chips
on, so that required a 6/6 process, which I can't do. A commercial
board producer makes them when I need them; but for more conventional
designs, or prototypes, I still (mostly) make them myself.

Photoetch can always be nicer than toner transfer, the problem is
getting a good dense pattern, and properly sensitizing the boards (or
buying them sensitized, rather expensive).

Alignment is also critical, and will be more critical the smaller the
trace and via size.

Harvey

Harvey,

I purposely didn't mention eyelets. Aside from the tedium of placing large numbers of them, the process to keep the flare on one side, while getting a proper flare on the other is quite tricky.  I have seen boards where the eyelets have been smashed flat.  While that seem to work, the solder connects the eyelet only at the periphery of the eyelet, leading to eventual failure with solder cracks at the periphery. Yes, with proper tooling, and good soldering practices they do work, but IMHO, they are not worth the trouble. They don't look good either :-)

Your lamination process sounds interesting.  I might try it st some point.  I am confused about the pins relative to the floor tiles.  How do you place the pins so that they don't interfere with the tiles?

(Another) Harvey

 

On Fri, 18 Mar 2016 20:21:11 -0700, you wrote:

>Brad,
>
>You are correct, this is quite a challenging project.
>
>Plated through holes:
>
>If you look at the board artwork in the article, you will find a view
>where they show the overlap between top and bottom patterns. At every
>location where the pads on the top and bottom have traces attached,
>there needs to be a connection between the top layer and the bottom
>layer. A board with plated through holes has a lining of copper plated
>into the holes to make those connections. Where there are no plated
>holes, the connection can be made by one of several methods. The
>easiest is to use the wires that go through the holes. For example,
>where a resistor or IC lead is in the hole, it would need to be soldered
>both top and bottom. For holes that just make a connection from the top
>to the bottom, a wire can be placed in the hole and soldered top and
>bottom. I usually make a small stub that is bent over at the end of the
>wire. I drop it into the hole and solder. Then I bend the wire the
>opposite way on the other side, and solder. This is called a "z"
>wire. Plated through holes are the best way to go, but are difficult to
>do in the home lab.

You can use eyelets, however, those are quite large in comparison, and
you need a source for them, and a staking tool.

>
>There are several complications associated with making two sided boards.
>The first, and most obvious, is that the two patterns have to be very
>closely aligned. This is required because of the connections between
>the two sizes. The holes must be drilled such that they pass through the
>pads on both sides. The actual etching process is also fraught with
>problems. You can choose to etch both sides at the same time, or
>protect one side from the etchant while etching the first side. Then
>reverse the procedure by protecting the first side and etching the
>second. The second process is tedious, but may result in better
>boards. It is hard to get both sides to etch evenly, and I frequently
>would wind up with over etching on one side when I tried to etch both at
>the same time. This is especially true with large boards such as the
>ones in this project.

I have tried both approaches, protecting a board side (you use
transparent contact paper), or not (you hope that it works well as you
have noted.)

However, I've done several things that seem to work well in
combination.

1) toner transfer top and bottom on two thinner boards. The material
I have is 0.021 or so and single sided, so that is good.

2) etch as needed.

3) drill the alignment holes *very* precisely. You'd like them within
about 0.002 of where they should be. I think I can get that close. I
can get rather thin vias to line up properly when using a #78 drill
(IIRC), using 10/10 for the process. I use #26 wire wrap wire,
stripped, for lacing the vias together.

However, I put a coating of long setting epoxy (about 1 hour work
time) on the boards. Cover the entire outside surface of the board
with masking tape, (keeps fingerprints off the copper), align the
boards with relatively thick pins, tape them so they cannot move, then
put them between two floor tiles to hold them flat while the epoxy
cures.

You get some well aligned boards that way, and if you screw up a
board, you only mess up one side.

Harvey

>
>(Another Harvey)
>
>
>On 3/18/2016 7:36 PM, 'Brad' unclefalter@... [Homebrew_PCBs] wrote:
>>
>> Separate discussion.
>>
>> I’m not planning to tackle this anytime soon, but I have been slowly
>> acquiring parts and am hoping after I’ve gained lots of experience to
>> one day build a Mark-8 replica.
>>
>> I expect this would be a very challenging project, which is why it’s
>> long in the future. But I’m always interested, always reading and
>> learning.
>>
>> Jon Titus, the creator, arranged with a New Jersey company to produce
>> board sets hobbyists could order, similar to the TVT. Those obviously
>> are ultra rare unobtanium now, however, I’m guessing the presence of
>> circuit board patterns in the construction details
>> (http://bytecollector.com/archive/mark_8/My_Mark-8_Info/Mark-8_Construction/RE_Mark-8_Const-NEW.pdf
>> -- page 25 or so) indicates it was at least possible some hobbyists
>> went and made their own, correct?
>>
>> I’m wondering – what differs in etching with double sided projects?
>> And when they say the holes weren’t plated through, does it mean what
>> I think it means (there would be a copper connection between a trace
>> on one side through a hole the component is soldered into through to
>> the other side?). Not sure I’m understanding how the connections
>> would be made from one side to the other.
>>
>>

You may find this useful:
https://hackaday.io/project/7938-pcb-smt-maker-lab-home

I do single pass toner transfer -double sided with good registration
permitting a single etch .
Ancel

On Fri, 18 Mar 2016 22:54:21 -0700, you wrote:

>Harvey,
>
>I purposely didn't mention eyelets. Aside from the tedium of placing
>large numbers of them, the process to keep the flare on one side, while
>getting a proper flare on the other is quite tricky.

I agree, I have a professional staking tool that does that. Came upon
it by complete coincidence. I'd not be using the eyelets otherwise.

>I have seen boards
>where the eyelets have been smashed flat. While that seem to work, the
>solder connects the eyelet only at the periphery of the eyelet, leading
>to eventual failure with solder cracks at the periphery. Yes, with
>proper tooling, and good soldering practices they do work, but IMHO,
>they are not worth the trouble. They don't look good either:-)

Agreed, and they're quite large for the boards that I use.

>
>Your lamination process sounds interesting. I might try it st some
>point. I am confused about the pins relative to the floor tiles. How do
>you place the pins so that they don't interfere with the tiles?

I really don't quite do what you mention, but I see I didn't detail
that well enough.

I use large push-in map pins for alignment. I could use almost
anything, but basically, the larger the pin the better the alignment
since the pins cannot be allowed to wobble. Once the board is
aligned, and with the pins still in. I tape the edges together on all
four sides. Then I remove the pins. That allows it to lay flat
between the floor tiles.

The nice thing about the floor tiles is that the epoxy doesn't stick
to them, and if it does, the board can be popped off rather easily.

You really want the hour setting epoxy, but if you can't get it, then
you have to mix small batches, say enough for only two boards
depending on the time the epoxy takes to set.

Harvey

>
>(Another) Harvey
>
>On 3/18/2016 9:16 PM, Harvey White madyn@...
>[Homebrew_PCBs] wrote:
>>
>> On Fri, 18 Mar 2016 20:21:11 -0700, you wrote:
>>
>> >Brad,
>> >
>> >You are correct, this is quite a challenging project.
>> >
>> >Plated through holes:
>> >
>> >If you look at the board artwork in the article, you will find a view
>> >where they show the overlap between top and bottom patterns. At every
>> >location where the pads on the top and bottom have traces attached,
>> >there needs to be a connection between the top layer and the bottom
>> >layer. A board with plated through holes has a lining of copper plated
>> >into the holes to make those connections. Where there are no plated
>> >holes, the connection can be made by one of several methods. The
>> >easiest is to use the wires that go through the holes. For example,
>> >where a resistor or IC lead is in the hole, it would need to be soldered
>> >both top and bottom. For holes that just make a connection from the top
>> >to the bottom, a wire can be placed in the hole and soldered top and
>> >bottom. I usually make a small stub that is bent over at the end of the
>> >wire. I drop it into the hole and solder. Then I bend the wire the
>> >opposite way on the other side, and solder. This is called a "z"
>> >wire. Plated through holes are the best way to go, but are difficult to
>> >do in the home lab.
>>
>> You can use eyelets, however, those are quite large in comparison, and
>> you need a source for them, and a staking tool.
>>
>> >
>> >There are several complications associated with making two sided boards.
>> >The first, and most obvious, is that the two patterns have to be very
>> >closely aligned. This is required because of the connections between
>> >the two sizes. The holes must be drilled such that they pass through the
>> >pads on both sides. The actual etching process is also fraught with
>> >problems. You can choose to etch both sides at the same time, or
>> >protect one side from the etchant while etching the first side. Then
>> >reverse the procedure by protecting the first side and etching the
>> >second. The second process is tedious, but may result in better
>> >boards. It is hard to get both sides to etch evenly, and I frequently
>> >would wind up with over etching on one side when I tried to etch both at
>> >the same time. This is especially true with large boards such as the
>> >ones in this project.
>>
>> I have tried both approaches, protecting a board side (you use
>> transparent contact paper), or not (you hope that it works well as you
>> have noted.)
>>
>> However, I've done several things that seem to work well in
>> combination.
>>
>> 1) toner transfer top and bottom on two thinner boards. The material
>> I have is 0.021 or so and single sided, so that is good.
>>
>> 2) etch as needed.
>>
>> 3) drill the alignment holes *very* precisely. You'd like them within
>> about 0.002 of where they should be. I think I can get that close. I
>> can get rather thin vias to line up properly when using a #78 drill
>> (IIRC), using 10/10 for the process. I use #26 wire wrap wire,
>> stripped, for lacing the vias together.
>>
>> However, I put a coating of long setting epoxy (about 1 hour work
>> time) on the boards. Cover the entire outside surface of the board
>> with masking tape, (keeps fingerprints off the copper), align the
>> boards with relatively thick pins, tape them so they cannot move, then
>> put them between two floor tiles to hold them flat while the epoxy
>> cures.
>>
>> You get some well aligned boards that way, and if you screw up a
>> board, you only mess up one side.
>>
>> Harvey
>>
>> >
>> >(Another Harvey)
>> >
>> >
>> >On 3/18/2016 7:36 PM, 'Brad' unclefalter@... [Homebrew_PCBs] wrote:
>> >>
>> >> Separate discussion.
>> >>
>> >> I’m not planning to tackle this anytime soon, but I have been slowly
>> >> acquiring parts and am hoping after I’ve gained lots of experience to
>> >> one day build a Mark-8 replica.
>> >>
>> >> I expect this would be a very challenging project, which is why it’s
>> >> long in the future. But I’m always interested, always reading and
>> >> learning.
>> >>
>> >> Jon Titus, the creator, arranged with a New Jersey company to produce
>> >> board sets hobbyists could order, similar to the TVT. Those obviously
>> >> are ultra rare unobtanium now, however, I’m guessing the presence of
>> >> circuit board patterns in the construction details
>> >>
>> (http://bytecollector.com/archive/mark_8/My_Mark-8_Info/Mark-8_Construction/RE_Mark-8_Const-NEW.pdf
>>
>> >> -- page 25 or so) indicates it was at least possible some hobbyists
>> >> went and made their own, correct?
>> >>
>> >> I’m wondering – what differs in etching with double sided projects?
>> >> And when they say the holes weren’t plated through, does it mean what
>> >> I think it means (there would be a copper connection between a trace
>> >> on one side through a hole the component is soldered into through to
>> >> the other side?). Not sure I’m understanding how the connections
>> >> would be made from one side to the other.
>> >>
>> >>
>>
>>

Ancel,

Thanks for the link.  He has some interesting approaches. I was with him all the way until the Nitric Acid.  Bad stuff in any concentration.  Luckily, this works with our more conventional etchants.

My issues with double sided are not registration, I use similar pins, but mine are the ones with the metal tops.  I found those to be more uniform in diameter from one pin to the next.  My problem has always been getting uniform etching on both sides.  At one point, I built a vertical bubble etcher with a heater for ferric chloride etching.  I arranged the bubbler such that I had coverage on both sides.  The results was that the edge of the board closest to the bubbler became over etched, while the area furthest away was only beginning to etch.  I envied the spray etchers my company used in their PWB production area. My best results were obtained by fully masking off one side while etching the other.  Tedious, but it works.

(Another) Harvey

 

You may find this useful:
https://hackaday.io/project/7938-pcb-smt-maker-lab-home

I do single pass toner transfer -double sided with good registration
permitting a single etch .
Ancel

On Sat, 19 Mar 2016 10:31:19 -0700, you wrote:

>Ancel,
>
>Thanks for the link. He has some interesting approaches. I was with him
>all the way until the Nitric Acid. Bad stuff in any concentration.
>Luckily, this works with our more conventional etchants.
>
>My issues with double sided are not registration, I use similar pins,
>but mine are the ones with the metal tops. I found those to be more
>uniform in diameter from one pin to the next.

I should probably get some drill rod and make a fixture.

>My problem has always
>been getting uniform etching on both sides. At one point, I built a
>vertical bubble etcher with a heater for ferric chloride etching. I
>arranged the bubbler such that I had coverage on both sides. The
>results was that the edge of the board closest to the bubbler became
>over etched, while the area furthest away was only beginning to etch.

Exactly what happens. I ended up monitoring the process and moving
the boards around. Since I do one side only, it's easier to monitor.
I've also been known to turn the boards upside down. It will make a
difference, but it's not a hands-free process.

I use HCL and peroxide, and that works well enough. I would like to
use sodium persulphate, and I actually found a flow tank (two aquarium
pumps and shaped plastic) to use with that etchant, but I am quite
wary about using it with anything with acid in it. It has a heater as
well.

>I envied the spray etchers my company used in their PWB production area.

Love to have one, there are some construction articles around, though.

>My best results were obtained by fully masking off one side while
>etching the other. Tedious, but it works.

it certainly does. The epoxy board method makes the process somewhat
more manageable.

Harvey

>
>(Another) Harvey
>
>On 3/19/2016 2:12 AM, AncelB mosaicmerc@... [Homebrew_PCBs] wrote:
>>
>> You may find this useful:
>> https://hackaday.io/project/7938-pcb-smt-maker-lab-home
>>
>> I do single pass toner transfer -double sided with good registration
>> permitting a single etch .
>> Ancel
>>
>>

When I was doing my dual side PCBs at home (70’s and early 80’s),
I always used two single side 0.031” copper clad FR4 that I etched while single sided.
I drilled the registration holes (3 in a different corner), then I glued (two part epoxy)
the two single side PCBs using the three pins to align the boards properly, then I
secured the two boards with two pieces of plywood and two C-clamps, then waiting for
the glue to cure in a warm oven to speed up the curing.

When the glue was cured, I drilled all the holes, and installed the eyelets using a
small harbor press with the proper punch and die.
The top side was the eyelet collar and the other side (tube) was broken in four parts
by the punch, so proper soldering was easy and very reliable.

I never had a failure of these eyelets.

Just my $0.02,
Jean-Paul
N1JPL

> On Mar 19, 2016, at 3:27 PM, Harvey White madyn@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
>
> On Sat, 19 Mar 2016 10:31:19 -0700, you wrote:
>
> >Ancel,
> >
> >Thanks for the link. He has some interesting approaches. I was with him
> >all the way until the Nitric Acid. Bad stuff in any concentration.
> >Luckily, this works with our more conventional etchants.
> >
> >My issues with double sided are not registration, I use similar pins,
> >but mine are the ones with the metal tops. I found those to be more
> >uniform in diameter from one pin to the next.
>
> I should probably get some drill rod and make a fixture.
>
> >My problem has always
> >been getting uniform etching on both sides. At one point, I built a
> >vertical bubble etcher with a heater for ferric chloride etching. I
> >arranged the bubbler such that I had coverage on both sides. The
> >results was that the edge of the board closest to the bubbler became
> >over etched, while the area furthest away was only beginning to etch.
>
> Exactly what happens. I ended up monitoring the process and moving
> the boards around. Since I do one side only, it's easier to monitor.
> I've also been known to turn the boards upside down. It will make a
> difference, but it's not a hands-free process.
>
> I use HCL and peroxide, and that works well enough. I would like to
> use sodium persulphate, and I actually found a flow tank (two aquarium
> pumps and shaped plastic) to use with that etchant, but I am quite
> wary about using it with anything with acid in it. It has a heater as
> well.
>
> >I envied the spray etchers my company used in their PWB production area.
>
> Love to have one, there are some construction articles around, though.
>
> >My best results were obtained by fully masking off one side while
> >etching the other. Tedious, but it works.
>
> it certainly does. The epoxy board method makes the process somewhat
> more manageable.
>
> Harvey
>
> >
> >(Another) Harvey
> >
> >On 3/19/2016 2:12 AM, AncelB mosaicmerc@... [Homebrew_PCBs] wrote:
> >>
> >> You may find this useful:
> >> https://hackaday.io/project/7938-pcb-smt-maker-lab-home
> >>
> >> I do single pass toner transfer -double sided with good registration
> >> permitting a single etch .
> >> Ancel
> >>
> >>
>
>
>

I do RF PCBs requiring micro strips etc. It must use double sided FR4 boards with consistent permittivity and very accurate trace thicknesses for impedance matching or inductance chokes.
The hackaday technique assures such results repeatably.
All acids must be handled properly, I have 30 years experience with conc. NITRIC and never a problem. HCL is also dangerous, fumes,  and can emit large volumes of chlorine if it comes into contact with household ammonia cleaners.
http://www.flinnsci.com/media/396140/acidsafety.pdf

When nitric is etching copper it bubbles a bit and self stirs the mix for cleaner trace edges I have found. Also the fine even bubble generation reveals any improperly cleaned copper areas within a couple seconds. Such areas can lead to longer immersion times which will cause over etching of the properly cleaned areas. In effect it gives me quality control feedback that other etchants don't.

Further, the copper nitrate end product is beneficial to sewer systems for restricting root growth, a fungicide or as a soak for preserving outdoor wooden surfaces.

• Cupric Nitrate (Copper Nitrate) Cu(NO3)2·nH2O, green powder or blue crystals which is soluble in water; used in electroplating copper on iron; as a catalyst and nitrating agent in organic reactions; component in rocket fuel; fungicides and wood preservatives; textile dyeing and printing; pigment in ceramics;

The formula you show is for Copper (II) Nitrate Hydrate.  That is bad stuff. See pdf attached. The benefit to sewer systems is not in the processing of sewage or quality of the effluent water, but is beneficial to to operator and/or homeowner who has roots infiltrating his pipes.  Some use sulfuric acid for the same function.  Neither belongs in the effluent of the sewer system on a steady basis.

Your reference to one application of the cupric nitrate is as part of a rocket fuel.  Of course, that is because it is a powerful oxidizer.  I am glad I looked at the MSDS.  It is one thing to buy highly concentrated Hydrogen Peroxide, knowing it is a powerful oxidizer, and having a label that says so, it is another to dry out the residue from your etch tanks and be left unaware that you have just made the same type of material.  It doesn't come with a label.  Thanks for the heads up.

The term dilute Nitric acid is relatively meaningless.  Unless the concentration is specified, I would not know what to order from a chemical supplier.  If I have to buy concentrated Nitric acid and experiment to make the required concentration, that is a step I prefer to avoid. I much prefer the pool acid I can buy at HD, 2 gals for approx $10, and that I keep for use in my pool.  This comes in a concentration of 14-15% (concentrated is 35-38%), is cheap and available without special shipping precautions.  During the course of my career, I have handled concentrated Hydrochloric, Sulfuric, Nitric, Hydrofluoric and Acetic acids.  Some of them in combination at high temperatures.  This was always done under a fume hood with gloves thick enough to make picking up small things very difficult.  There were occasional spills and cleanups, all contained within the equipment, and I still have all my fingers and toes, both eyes work, and no acid burns on my body.  Yes, you can get very hurt by the 15% pool acid, but some care, common sense and preparation goes a long way to mitigating the probability of such an occurrence.

I don't think we need to get into a full blown discussion about this.  We each have our like and dislikes, and we should agree to disagree.

(Another) Harvey

 

I do RF PCBs requiring micro strips etc. It must use double sided FR4 boards with consistent permittivity and very accurate trace thicknesses for impedance matching or inductance chokes.
The hackaday technique assures such results repeatably.
All acids must be handled properly, I have 30 years experience with conc. NITRIC and never a problem. HCL is also dangerous, fumes,  and can emit large volumes of chlorine if it comes into contact with household ammonia cleaners.
http://www.flinnsci.com/media/396140/acidsafety.pdf

When nitric is etching copper it bubbles a bit and self stirs the mix for cleaner trace edges I have found. Also the fine even bubble generation reveals any improperly cleaned copper areas within a couple seconds. Such areas can lead to longer immersion times which will cause over etching of the properly cleaned areas. In effect it gives me quality control feedback that other etchants don't.

Further, the copper nitrate end product is beneficial to sewer systems for restricting root growth, a fungicide or as a soak for preserving outdoor wooden surfaces.

• Cupric Nitrate (Copper Nitrate) Cu(NO3)2·nH2O, green powder or blue crystals which is soluble in water; used in electroplating copper on iron; as a catalyst and nitrating agent in organic reactions; component in rocket fuel; fungicides and wood preservatives; textile dyeing and printing; pigment in ceramics;

The usual place would be a chemical supply house.  Be aware that this is classed as a hazardous material, and there are extra HAZMAT fees associated with it's shipment.  OTOH, if you are a moonshiner, you can make your own. Check this out:

https://www.youtube.com/watch?v=qzu3UidPkro

If you can do this without getting hurt, then you can etch with Nitric with my blessing :-)

(Another) Harvey

 

Where is nitric acid found?  Is it practical compared to HCl/H202 or FeCl?

 

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Sunday, March 20, 2016 2:26 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs

 

 

I do RF PCBs requiring micro strips etc. It must use double sided FR4 boards with consistent permittivity and very accurate trace thicknesses for impedance matching or inductance chokes.
The hackaday technique assures such results repeatably.
All acids must be handled properly, I have 30 years experience with conc. NITRIC and never a problem. HCL is also dangerous, fumes,  and can emit large volumes of chlorine if it comes into contact with household ammonia cleaners.
http://www.flinnsci.com/media/396140/acidsafety.pdf

When nitric is etching copper it bubbles a bit and self stirs the mix for cleaner trace edges I have found. Also the fine even bubble generation reveals any improperly cleaned copper areas within a couple seconds. Such areas can lead to longer immersion times which will cause over etching of the properly cleaned areas. In effect it gives me quality control feedback that other etchants don't.

Further, the copper nitrate end product is beneficial to sewer systems for restricting root growth, a fungicide or as a soak for preserving outdoor wooden surfaces.

• Cupric Nitrate (Copper Nitrate) Cu(NO3)2·nH2O, green powder or blue crystals which is soluble in water; used in electroplating copper on iron; as a catalyst and nitrating agent in organic reactions; component in rocket fuel; fungicides and wood preservatives; textile dyeing and printing; pigment in ceramics;

On Mon, 21 Mar 2016 19:35:54 -0400, you wrote:

>Anyone here besides me ever use ammonium persulfate? When I worked in an electronics plan that was what we used to etch our boards. We would put it in a corningware baking pan and put it on a small hotplate to keep it warm. It was fairly quick depending on what concentration you used . it is an oxidixer ,mix with sugar and heat it goes boom!

I wanted to, and I've found it hard to come by. I'd rather use it,
since I have an etchant tank developed specifically for it. HCL and
peroxide are very inexpensive, and easy to find.

Harvey

>
>
>
>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>Sent: Sunday, March 20, 2016 2:53 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: RE: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
>
>
>
>
>
>Where is nitric acid found? Is it practical compared to HCl/H202 or FeCl?
>
>
>
>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>Sent: Sunday, March 20, 2016 2:26 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
>
>
>
>
>
>I do RF PCBs requiring micro strips etc. It must use double sided FR4 boards with consistent permittivity and very accurate trace thicknesses for impedance matching or inductance chokes.
>The hackaday technique assures such results repeatably.
>All acids must be handled properly, I have 30 years experience with conc. NITRIC and never a problem. HCL is also dangerous, fumes, and can emit large volumes of chlorine if it comes into contact with household ammonia cleaners.
>http://www.flinnsci.com/media/396140/acidsafety.pdf
>
>When nitric is etching copper it bubbles a bit and self stirs the mix for cleaner trace edges I have found. Also the fine even bubble generation reveals any improperly cleaned copper areas within a couple seconds. Such areas can lead to longer immersion times which will cause over etching of the properly cleaned areas. In effect it gives me quality control feedback that other etchants don't.
>
>Further, the copper nitrate end product is beneficial to sewer systems for restricting root growth, a fungicide or as a soak for preserving outdoor wooden surfaces.
>
>* Cupric Nitrate (Copper Nitrate) Cu(NO3)2·nH2O, green powder or blue crystals which is soluble in water; used in electroplating copper on iron; as a catalyst and nitrating agent in organic reactions; component in rocket fuel; fungicides and wood preservatives; textile dyeing and printing; pigment in ceramics;
>
>
>
>
>
>
>

We used hydrofluoric in my Failure Analysis Laboratory.  We buffered it with ammonium fluoride, as I remember it.  It was used to remove the glass over layer from integrated circuits that were in for fault analysis.  Much later, we acquired a plasma etcher that used fluorine compound gases to remove glass and silicon nitride.  We still kept the acid on hand because there were times when we needed it.

Hated that stuff.

(Another) Harvey

 

Hydrofluoric is very dangerous. If you wish to use it ,you can get it at heating=cooling supply houses. I work in that trade and will not use it,just too dangerous. It is a calcium seeking acid and can penetrate right through your skin and dissolve your bones!

 

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Sunday, March 20, 2016 5:01 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: Re: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs [1 Attachment]

 

 

The formula you show is for Copper (II) Nitrate Hydrate.  That is bad stuff. See pdf attached. The benefit to sewer systems is not in the processing of sewage or quality of the effluent water, but is beneficial to to operator and/or homeowner who has roots infiltrating his pipes.  Some use sulfuric acid for the same function.  Neither belongs in the effluent of the sewer system on a steady basis.

Your reference to one application of the cupric nitrate is as part of a rocket fuel.  Of course, that is because it is a powerful oxidizer.  I am glad I looked at the MSDS.  It is one thing to buy highly concentrated Hydrogen Peroxide, knowing it is a powerful oxidizer, and having a label that says so, it is another to dry out the residue from your etch tanks and be left unaware that you have just made the same type of material.  It doesn't come with a label.  Thanks for the heads up.

The term dilute Nitric acid is relatively meaningless.  Unless the concentration is specified, I would not know what to order from a chemical supplier.  If I have to buy concentrated Nitric acid and experiment to make the required concentration, that is a step I prefer to avoid. I much prefer the pool acid I can buy at HD, 2 gals for approx $10, and that I keep for use in my pool.  This comes in a concentration of 14-15% (concentrated is 35-38%), is cheap and available without special shipping precautions.  During the course of my career, I have handled concentrated Hydrochloric, Sulfuric, Nitric, Hydrofluoric and Acetic acids.  Some of them in combination at high temperatures.  This was always done under a fume hood with gloves thick enough to make picking up small things very difficult.  There were occasional spills and cleanups, all contained within the equipment, and I still have all my fingers and toes, both eyes work, and no acid burns on my body.  Yes, you can get very hurt by the 15% pool acid, but some care, common sense and preparation goes a long way to mitigating the probability of such an occurrence.

I don't think we need to get into a full blown discussion about this.  We each have our like and dislikes, and we should agree to disagree.

(Another) Harvey

On 3/20/2016 11:25 AM, AncelB mosaicmerc@... [Homebrew_PCBs] wrote:

 

I do RF PCBs requiring micro strips etc. It must use double sided FR4 boards with consistent permittivity and very accurate trace thicknesses for impedance matching or inductance chokes.
The hackaday technique assures such results repeatably.
All acids must be handled properly, I have 30 years experience with conc. NITRIC and never a problem. HCL is also dangerous, fumes,  and can emit large volumes of chlorine if it comes into contact with household ammonia cleaners.
http://www.flinnsci.com/media/396140/acidsafety.pdf

When nitric is etching copper it bubbles a bit and self stirs the mix for cleaner trace edges I have found. Also the fine even bubble generation reveals any improperly cleaned copper areas within a couple seconds. Such areas can lead to longer immersion times which will cause over etching of the properly cleaned areas. In effect it gives me quality control feedback that other etchants don't.

Further, the copper nitrate end product is beneficial to sewer systems for restricting root growth, a fungicide or as a soak for preserving outdoor wooden surfaces.

• Cupric Nitrate (Copper Nitrate) Cu(NO3)2·nH2O, green powder or blue crystals which is soluble in water; used in electroplating copper on iron; as a catalyst and nitrating agent in organic reactions; component in rocket fuel; fungicides and wood preservatives; textile dyeing and printing; pigment in ceramics;

 

I used it for a short time.  I loved that I could see the etch process through the solution.  I think I stopped because I couldn't get it any more.

 

Anyone here besides me ever use ammonium persulfate? When I worked in an electronics plan that was what we used to etch our boards. We would put it in a corningware baking pan and put it on a small hotplate to keep it warm. It was fairly quick depending on what concentration you used . it is an oxidixer ,mix with sugar and heat it goes boom!

 

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Sunday, March 20, 2016 2:53 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: RE: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs

 

 

Where is nitric acid found?  Is it practical compared to HCl/H202 or FeCl?

 

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Sunday, March 20, 2016 2:26 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs

 

 

I do RF PCBs requiring micro strips etc. It must use double sided FR4 boards with consistent permittivity and very accurate trace thicknesses for impedance matching or inductance chokes.
The hackaday technique assures such results repeatably.
All acids must be handled properly, I have 30 years experience with conc. NITRIC and never a problem. HCL is also dangerous, fumes,  and can emit large volumes of chlorine if it comes into contact with household ammonia cleaners.
http://www.flinnsci.com/media/396140/acidsafety.pdf

When nitric is etching copper it bubbles a bit and self stirs the mix for cleaner trace edges I have found. Also the fine even bubble generation reveals any improperly cleaned copper areas within a couple seconds. Such areas can lead to longer immersion times which will cause over etching of the properly cleaned areas. In effect it gives me quality control feedback that other etchants don't.

Further, the copper nitrate end product is beneficial to sewer systems for restricting root growth, a fungicide or as a soak for preserving outdoor wooden surfaces.

• Cupric Nitrate (Copper Nitrate) Cu(NO3)2·nH2O, green powder or blue crystals which is soluble in water; used in electroplating copper on iron; as a catalyst and nitrating agent in organic reactions; component in rocket fuel; fungicides and wood preservatives; textile dyeing and printing; pigment in ceramics;

 

Anyone here besides me ever use ammonium persulfate? When I worked in an electronics plan that was what we used to etch our boards. We would put it in a corningware baking pan and put it on a small hotplate to keep it warm. It was fairly quick depending on what concentration you used . it is an oxidixer ,mix with sugar and heat it goes boom!

 

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Sunday, March 20, 2016 2:53 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: RE: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs

 

 

Where is nitric acid found?  Is it practical compared to HCl/H202 or FeCl?

 

From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
Sent: Sunday, March 20, 2016 2:26 PM
To: Homebrew_PCBs@yahoogroups.com
Subject: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs

 

 

I do RF PCBs requiring micro strips etc. It must use double sided FR4 boards with consistent permittivity and very accurate trace thicknesses for impedance matching or inductance chokes.
The hackaday technique assures such results repeatably.
All acids must be handled properly, I have 30 years experience with conc. NITRIC and never a problem. HCL is also dangerous, fumes,  and can emit large volumes of chlorine if it comes into contact with household ammonia cleaners.
http://www.flinnsci.com/media/396140/acidsafety.pdf

When nitric is etching copper it bubbles a bit and self stirs the mix for cleaner trace edges I have found. Also the fine even bubble generation reveals any improperly cleaned copper areas within a couple seconds. Such areas can lead to longer immersion times which will cause over etching of the properly cleaned areas. In effect it gives me quality control feedback that other etchants don't.

Further, the copper nitrate end product is beneficial to sewer systems for restricting root growth, a fungicide or as a soak for preserving outdoor wooden surfaces.

• Cupric Nitrate (Copper Nitrate) Cu(NO3)2·nH2O, green powder or blue crystals which is soluble in water; used in electroplating copper on iron; as a catalyst and nitrating agent in organic reactions; component in rocket fuel; fungicides and wood preservatives; textile dyeing and printing; pigment in ceramics;

-- 
Cecil - k5nwa
http://thepartsplace.k5nwa.com/

On Mon, 21 Mar 2016 23:47:54 -0700, you wrote:

>According to a search, MG Chemicals sells ammonium persulfate. In my area Fry’s Electronics says they have it for $32/Kg. I hadn’t thought to look there.

That's very very expensive. You'd possibly get better prices from a
chemical supply house. The etching tank I have needs about half a kg
per load. Not in the least competitive with CuCl.....

Harvey

>
>
>
>Andrew
>
>
>
>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>Sent: Monday, March 21, 2016 6:54 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: Re: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
>
>
>
>
>
>I used it for a short time. I loved that I could see the etch process through the solution. I think I stopped because I couldn't get it any more.
>
>On 3/21/2016 4:35 PM, 'keith printy' keethpr@... [Homebrew_PCBs] wrote:
>
>
>
>Anyone here besides me ever use ammonium persulfate? When I worked in an electronics plan that was what we used to etch our boards. We would put it in a corningware baking pan and put it on a small hotplate to keep it warm. It was fairly quick depending on what concentration you used . it is an oxidixer ,mix with sugar and heat it goes boom!
>
>
>
>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>Sent: Sunday, March 20, 2016 2:53 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: RE: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
>
>
>
>
>
>Where is nitric acid found? Is it practical compared to HCl/H202 or FeCl?
>
>
>
>From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>Sent: Sunday, March 20, 2016 2:26 PM
>To: Homebrew_PCBs@yahoogroups.com
>Subject: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
>
>
>
>
>
>I do RF PCBs requiring micro strips etc. It must use double sided FR4 boards with consistent permittivity and very accurate trace thicknesses for impedance matching or inductance chokes.
>The hackaday technique assures such results repeatably.
>All acids must be handled properly, I have 30 years experience with conc. NITRIC and never a problem. HCL is also dangerous, fumes, and can emit large volumes of chlorine if it comes into contact with household ammonia cleaners.
>http://www.flinnsci.com/media/396140/acidsafety.pdf
>
>When nitric is etching copper it bubbles a bit and self stirs the mix for cleaner trace edges I have found. Also the fine even bubble generation reveals any improperly cleaned copper areas within a couple seconds. Such areas can lead to longer immersion times which will cause over etching of the properly cleaned areas. In effect it gives me quality control feedback that other etchants don't.
>
>Further, the copper nitrate end product is beneficial to sewer systems for restricting root growth, a fungicide or as a soak for preserving outdoor wooden surfaces.
>
>* Cupric Nitrate (Copper Nitrate) Cu(NO3)2·nH2O, green powder or blue crystals which is soluble in water; used in electroplating copper on iron; as a catalyst and nitrating agent in organic reactions; component in rocket fuel; fungicides and wood preservatives; textile dyeing and printing; pigment in ceramics;
>
>
>
>
>
>
>
>

The dilute Nitric mix I use has a Spec. Gravity of 1.215 when fresh.

It goes UP as it dissolves copper.

Ancel

Just curious, what is the difference between Ammonium persulfate (expensive $32/kg) and
Ammonium sulfate ($9.49/20lbs bag at Walmart)?

Jean-Paul
N1JPL

> On Mar 22, 2016, at 2:54 PM, 'K5ESS' k5ess.nothdurft@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
>
>
> If I read the material correctly on using ammonium persulfate as an etchant; one big drawback is that it has a fairly limited shelf life. It will lose its potency in thirty days or less just sitting on the shelf. For the infrequent user this means making a new batch each time you want to etch a board. That combined with a fairly high cost tends to make not too attractive.
>
> Many may have visited this site but here’s a good discussion on various etchants.
>
> http://www.pcbfx.com/main_site/pages/accessories/etchants.html
>
>
>
>
>
> Mike N.
>
> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> Sent: Tuesday, March 22, 2016 10:06 AM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: Re: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
>
>
>
>
>
> On Mon, 21 Mar 2016 23:47:54 -0700, you wrote:
>
> >According to a search, MG Chemicals sells ammonium persulfate. In my area Fry’s Electronics says they have it for $32/Kg. I hadn’t thought to look there.
>
> That's very very expensive. You'd possibly get better prices from a
> chemical supply house. The etching tank I have needs about half a kg
> per load. Not in the least competitive with CuCl.....
>
> Harvey
>
> >
> >
> >
> >Andrew
> >
> >
> >
> >From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> >Sent: Monday, March 21, 2016 6:54 PM
> >To: Homebrew_PCBs@yahoogroups.com
> >Subject: Re: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
> >
> >
> >
> >
> >
> >I used it for a short time. I loved that I could see the etch process through the solution. I think I stopped because I couldn't get it any more.
> >
> >On 3/21/2016 4:35 PM, 'keith printy' keethpr@... [Homebrew_PCBs] wrote:
> >
> >
> >
> >Anyone here besides me ever use ammonium persulfate? When I worked in an electronics plan that was what we used to etch our boards. We would put it in a corningware baking pan and put it on a small hotplate to keep it warm. It was fairly quick depending on what concentration you used . it is an oxidixer ,mix with sugar and heat it goes boom!
> >
> >
> >
> >From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> >Sent: Sunday, March 20, 2016 2:53 PM
> >To: Homebrew_PCBs@yahoogroups.com
> >Subject: RE: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
> >
> >
> >
> >
> >
> >Where is nitric acid found? Is it practical compared to HCl/H202 or FeCl?
> >
> >
> >
> >From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
> >Sent: Sunday, March 20, 2016 2:26 PM
> >To: Homebrew_PCBs@yahoogroups.com
> >Subject: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
> >
> >
> >
> >
> >
> >I do RF PCBs requiring micro strips etc. It must use double sided FR4 boards with consistent permittivity and very accurate trace thicknesses for impedance matching or inductance chokes.
> >The hackaday technique assures such results repeatably.
> >All acids must be handled properly, I have 30 years experience with conc. NITRIC and never a problem. HCL is also dangerous, fumes, and can emit large volumes of chlorine if it comes into contact with household ammonia cleaners.
> >http://www.flinnsci.com/media/396140/acidsafety.pdf
> >
> >When nitric is etching copper it bubbles a bit and self stirs the mix for cleaner trace edges I have found. Also the fine even bubble generation reveals any improperly cleaned copper areas within a couple seconds. Such areas can lead to longer immersion times which will cause over etching of the properly cleaned areas. In effect it gives me quality control feedback that other etchants don't.
> >
> >Further, the copper nitrate end product is beneficial to sewer systems for restricting root growth, a fungicide or as a soak for preserving outdoor wooden surfaces.
> >
> >* Cupric Nitrate (Copper Nitrate) Cu(NO3)2·nH2O, green powder or blue crystals which is soluble in water; used in electroplating copper on iron; as a catalyst and nitrating agent in organic reactions; component in rocket fuel; fungicides and wood preservatives; textile dyeing and printing; pigment in ceramics;
> >
> >
> >
> >
> >
> >
> >
> >
>
>
>
>

The persulfate has twice the oxygen and sulphur.
The oxygen will prefer to bond with the copper rather than another
oxygen, which is why it is so reactive.

In effect, ammonium sulphate from Walmart is the "used up" product,
minus the copper sulphate. You should try selling them your waste ;-).

Please be advised that I have no idea what I am talking about.

ST

On Tue, Mar 22, 2016 at 8:41 PM, Jean-Paul Louis louijp@...
[Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:

> Just curious, what is the difference between Ammonium persulfate (expensive $32/kg) and
> Ammonium sulfate ($9.49/20lbs bag at Walmart)?
>
> Jean-Paul
> N1JPL
>
>
>> On Mar 22, 2016, at 2:54 PM, 'K5ESS' k5ess.nothdurft@... [Homebrew_PCBs] <Homebrew_PCBs@yahoogroups.com> wrote:
>>
>>
>> If I read the material correctly on using ammonium persulfate as an etchant; one big drawback is that it has a fairly limited shelf life. It will lose its potency in thirty days or less just sitting on the shelf. For the infrequent user this means making a new batch each time you want to etch a board. That combined with a fairly high cost tends to make not too attractive.
>>
>> Many may have visited this site but here’s a good discussion on various etchants.
>>
>> http://www.pcbfx.com/main_site/pages/accessories/etchants.html
>>
>>
>>
>>
>>
>> Mike N.
>>
>> From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>> Sent: Tuesday, March 22, 2016 10:06 AM
>> To: Homebrew_PCBs@yahoogroups.com
>> Subject: Re: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
>>
>>
>>
>>
>>
>> On Mon, 21 Mar 2016 23:47:54 -0700, you wrote:
>>
>> >According to a search, MG Chemicals sells ammonium persulfate. In my area Fry’s Electronics says they have it for $32/Kg. I hadn’t thought to look there.
>>
>> That's very very expensive. You'd possibly get better prices from a
>> chemical supply house. The etching tank I have needs about half a kg
>> per load. Not in the least competitive with CuCl.....
>>
>> Harvey
>>
>> >
>> >
>> >
>> >Andrew
>> >
>> >
>> >
>> >From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>> >Sent: Monday, March 21, 2016 6:54 PM
>> >To: Homebrew_PCBs@yahoogroups.com
>> >Subject: Re: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
>> >
>> >
>> >
>> >
>> >
>> >I used it for a short time. I loved that I could see the etch process through the solution. I think I stopped because I couldn't get it any more.
>> >
>> >On 3/21/2016 4:35 PM, 'keith printy' keethpr@... [Homebrew_PCBs] wrote:
>> >
>> >
>> >
>> >Anyone here besides me ever use ammonium persulfate? When I worked in an electronics plan that was what we used to etch our boards. We would put it in a corningware baking pan and put it on a small hotplate to keep it warm. It was fairly quick depending on what concentration you used . it is an oxidixer ,mix with sugar and heat it goes boom!
>> >
>> >
>> >
>> >From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>> >Sent: Sunday, March 20, 2016 2:53 PM
>> >To: Homebrew_PCBs@yahoogroups.com
>> >Subject: RE: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
>> >
>> >
>> >
>> >
>> >
>> >Where is nitric acid found? Is it practical compared to HCl/H202 or FeCl?
>> >
>> >
>> >
>> >From: Homebrew_PCBs@yahoogroups.com [mailto:Homebrew_PCBs@yahoogroups.com]
>> >Sent: Sunday, March 20, 2016 2:26 PM
>> >To: Homebrew_PCBs@yahoogroups.com
>> >Subject: [Homebrew_PCBs] Re: Mark-8 'Non-plated through holes' and 2 sided PCBs
>> >
>> >
>> >
>> >
>> >
>> >I do RF PCBs requiring micro strips etc. It must use double sided FR4 boards with consistent permittivity and very accurate trace thicknesses for impedance matching or inductance chokes.
>> >The hackaday technique assures such results repeatably.
>> >All acids must be handled properly, I have 30 years experience with conc. NITRIC and never a problem. HCL is also dangerous, fumes, and can emit large volumes of chlorine if it comes into contact with household ammonia cleaners.
>> >http://www.flinnsci.com/media/396140/acidsafety.pdf
>> >
>> >When nitric is etching copper it bubbles a bit and self stirs the mix for cleaner trace edges I have found. Also the fine even bubble generation reveals any improperly cleaned copper areas within a couple seconds. Such areas can lead to longer immersion times which will cause over etching of the properly cleaned areas. In effect it gives me quality control feedback that other etchants don't.
>> >
>> >Further, the copper nitrate end product is beneficial to sewer systems for restricting root growth, a fungicide or as a soak for preserving outdoor wooden surfaces.
>> >
>> >* Cupric Nitrate (Copper Nitrate) Cu(NO3)2·nH2O, green powder or blue crystals which is soluble in water; used in electroplating copper on iron; as a catalyst and nitrating agent in organic reactions; component in rocket fuel; fungicides and wood preservatives; textile dyeing and printing; pigment in ceramics;
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>>
>>
>>
>>
>
>
>
> ------------------------------------
> Posted by: Jean-Paul Louis <louijp@...>
> ------------------------------------
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