Homebrew PCBs

While wishing that I had made a prototype first, mostly because it's 
a good idea and a lot of fun, I came up with an idea for soldermask.

Since we can use toner transfer for adding a silkscreen layer over a 
board, why not use toner transfer for adding a soldermask layer to 
the board? It could be even done in your favorite board color by 
using a color laser printer from a copy center. A negative image of 
the soldermask layer would be required. My software generates that 
if needed. The plastic toner soldermask layer would make an 
excellent barrier.

The next step would be to see if one could lay the toner transfer 
silkscreen layer over the toner transfer soldermask layer 
successfully with different colors?

My board (35mm x 40mm) can be panelized 25 times on one 8.5 x 11 
sheet. Even more on a legal sheet or larger. They use to charge $1 
for each sheet. So that's something like 5 cents per board after 
taxes.

If my rookie bare bones board design is ok when it arrives, then I'm 
going to try this idea.

Thoughts?

Mike

Chris showed a photo of a "novel" component legen a while ago - he printed  
the "real world" view of his PCB out and transferred that. So you can put  
legend over the mask, even in one go, probably even graphics if you like.

The problem with using it for soldermask will be that it is hard to do a  
transfer that continues over the edge of a trace, because of the step.

I had the very same idea (or Chris had it, i don't remember), anyway, we  
discussed it either here or on E_101, but i haven't had time to try it,  
and also i don't have a color laser.

If you try it make sure to show us.

ST


On Fri, 06 Jan 2006 17:31:54 +0100, Mike Phillips <mikep_95133@...>  
wrote:

> While wishing that I had made a prototype first, mostly because it's
>
> a good idea and a lot of fun, I came up with an idea for soldermask.
>
>
> Since we can use toner transfer for adding a silkscreen layer over a
>
> board, why not use toner transfer for adding a soldermask layer to
>
> the board? It could be even done in your favorite board color by
>
> using a color laser printer from a copy center. A negative image of
>
> the soldermask layer would be required. My software generates that
>
> if needed. The plastic toner soldermask layer would make an
>
> excellent barrier.
>
>
> The next step would be to see if one could lay the toner transfer
>
> silkscreen layer over the toner transfer soldermask layer
>
> successfully with different colors?
>
>
> My board (35mm x 40mm) can be panelized 25 times on one 8.5 x 11
>
> sheet. Even more on a legal sheet or larger. They use to charge $1
>
> for each sheet. So that's something like 5 cents per board after
>
> taxes.
>
>
> If my rookie bare bones board design is ok when it arrives, then I'm
>
> going to try this idea.
>
>
> Thoughts?
>
>
> Mike

Good point about the stepping over the traces. That can be tested 
with just my b/w laser at home.

I'd like to see Chris's photo. Where can I find it?

Mike



--- In Homebrew_PCBs@yahoogroups.com, "Stefan Trethan" 
<stefan_trethan@g...> wrote:
>
> Chris showed a photo of a "novel" component legen a while ago - he 
printed  
> the "real world" view of his PCB out and transferred that. So you 
can put  
> legend over the mask, even in one go, probably even graphics if 
you like.
> 
> The problem with using it for soldermask will be that it is hard 
to do a  
> transfer that continues over the edge of a trace, because of the 
step.
> 
> I had the very same idea (or Chris had it, i don't remember), 
anyway, we  
> discussed it either here or on E_101, but i haven't had time to 
try it,  
> and also i don't have a color laser.
> 
> If you try it make sure to show us.
> 
> ST
> 
> 
> On Fri, 06 Jan 2006 17:31:54 +0100, Mike Phillips 
<mikep_95133@y...>  
> wrote:
> 
> > While wishing that I had made a prototype first, mostly because 
it's
> >
> > a good idea and a lot of fun, I came up with an idea for 
soldermask.
> >
> >
> > Since we can use toner transfer for adding a silkscreen layer 
over a
> >
> > board, why not use toner transfer for adding a soldermask layer 
to
> >
> > the board? It could be even done in your favorite board color by
> >
> > using a color laser printer from a copy center. A negative image 
of
> >
> > the soldermask layer would be required. My software generates 
that
> >
> > if needed. The plastic toner soldermask layer would make an
> >
> > excellent barrier.
> >
> >
> > The next step would be to see if one could lay the toner transfer
> >
> > silkscreen layer over the toner transfer soldermask layer
> >
> > successfully with different colors?
> >
> >
> > My board (35mm x 40mm) can be panelized 25 times on one 8.5 x 11
> >
> > sheet. Even more on a legal sheet or larger. They use to charge 
$1
> >
> > for each sheet. So that's something like 5 cents per board after
> >
> > taxes.
> >
> >
> > If my rookie bare bones board design is ok when it arrives, then 
I'm

> >
> > going to try this idea.
> >
> >
> > Thoughts?
> >
> >
> > Mike
>

>Since we can use toner transfer for adding a silkscreen layer over a
>board, why not use toner transfer for adding a soldermask layer to
>the board? It could be even done in your favorite board color by
>using a color laser printer from a copy center. A negative image of
>the soldermask layer would be required. My software generates that
>if needed. The plastic toner soldermask layer would make an
>excellent barrier.
>
>
>Thoughts?
>
>Mike

My experience with this is that the temperature of the soldering iron will 
melt away the toner, defeating the purpose of the solder mask.
  I used to not even bother to remove the toner after etching, and just 
solder the pins right through the toner. I stopped doing that because, 
while it worked, it looked like crap.

-carl

Even with no toner on the component pads, the nearby toner would 
melt?

I'm not thinking of just a blanket coating of toner over everything, 
but of using a negative image of the soldermask layer to make the TT 
soldermask coating fit around all of the solder pads just like real 
soldermask.

Mike


 
> My experience with this is that the temperature of the soldering 
iron will 
> melt away the toner, defeating the purpose of the solder mask.
>   I used to not even bother to remove the toner after etching, and 
just 
> solder the pins right through the toner. I stopped doing that 
because, 

> while it worked, it looked like crap.
> 
> -carl
>

On Fri, 06 Jan 2006 18:31:52 +0100, Mike Phillips <mikep_95133@...>  
wrote:

> Good point about the stepping over the traces. That can be tested
>
> with just my b/w laser at home.
>
>
> I'd like to see Chris's photo. Where can I find it?
>
>
> Mike


i really don't know. On E_101 maybe.

It was not very sharp i believe.

ST

On Fri, 06 Jan 2006 19:01:39 +0100, Mike Phillips <mikep_95133@...>  
wrote:

> Even with no toner on the component pads, the nearby toner would
>
> melt?
>
>
> I'm not thinking of just a blanket coating of toner over everything,
>
> but of using a negative image of the soldermask layer to make the TT
>
> soldermask coating fit around all of the solder pads just like real
>
> soldermask.
>
>
> Mike


i plan to try for ages, but keep forgetting. will make many boards  
tomorrow anyway and try it.

ST

I uploaded the top copper layer and also the reverse image of the 
soldermask layer into my Files folder called Mike P's stuff. These 
pdf files might make more sense.

Here's the link.

http://groups.yahoo.com/group/Homebrew_PCBs/files/Mike%20P%27s%
20stuff/

Mike



--- In Homebrew_PCBs@yahoogroups.com, Henry Carl Ott <carlott@i...> 
wrote:
>
> 
> 
> >Since we can use toner transfer for adding a silkscreen layer 
over a
> >board, why not use toner transfer for adding a soldermask layer to
> >the board? It could be even done in your favorite board color by
> >using a color laser printer from a copy center. A negative image 
of
> >the soldermask layer would be required. My software generates that
> >if needed. The plastic toner soldermask layer would make an
> >excellent barrier.
> >
> >
> >Thoughts?
> >
> >Mike
> 
> My experience with this is that the temperature of the soldering 
iron will 
> melt away the toner, defeating the purpose of the solder mask.
>   I used to not even bother to remove the toner after etching, and 
just 
> solder the pins right through the toner. I stopped doing that 
because, 

> while it worked, it looked like crap.
> 
> -carl
>

> > I'd like to see Chris's photo. Where can I find it?
> >
> >
> > Mike


Sorry but it appears as though the photo is gone.  I just checked 
through both places and I can't find it so I must have deleted it.

Give it a try, you might be surprised as to how well it does work.  
Keep in mind though, toner is plastic and if you wanted, you could 
solder right through it.  However, in my tests, I printed out some 
different size circles and soldered in the middle of them and 
the "mask" seemed to contain the solder flow to that spot.

Chris

At 01:01 PM 1/6/2006, you wrote:
>Even with no toner on the component pads, the nearby toner would
>melt?
>
>I'm not thinking of just a blanket coating of toner over everything,
>but of using a negative image of the soldermask layer to make the TT
>soldermask coating fit around all of the solder pads just like real
>soldermask.
>
>Mike

I see what you are trying to do.
Toner does melt pretty easily. It also blobs up a bit and traps flux.

I can see three reasons for a solder mask (I'm sure there are more).
  1. Assist in soldering. Usually only necessary for wave soldering,  hand 
soldering fine pitch SMD, and /or using solder paste.
      Wave soldering,  hot air, hot plate, converted toaster oven, and 
paste would melt all the toner. On hand soldering smd I've noticed I get 
bridges between the actual part pins, not so much the pads, so I'm not sure 
how much help this type of mask would be. If it's not an smd board I don't 
see the need. If it is an smd board then alignment of the mask becomes a 
real issue.

2. Protect the copper traces from corrosion / physical damage. Actually a 
good use if you don't want to tin the board.
3. Esthetics. Mask does make a board look better, more professional.

So I can kind of see using a tt solder mask for 2&3, but not so much 1. I'm 
not sure it's worth the effort for prototypes.
  But hey, It's certainly easy enough to do some tests.

  I do love the idea of using a color laser printer and TT to do a 
silkscreen replacement. The toner is pretty tough, and you can always 
overcoat with letraset or equiv,. to protect it.

just my .02




carl

--------------------------------------------------------
Henry Carl Ott   N2RVQ
http://users.rcn.com/carlott/
--------------------------------------------------------

I only have pdf files, so the photo section would not accept them. 
Now they are deposited in the files section under Mike P's stuff.

Mike



--- In Homebrew_PCBs@yahoogroups.com, "lcdpublishing" 
<lcdpublishing@y...> wrote:
>
> 
> > > I'd like to see Chris's photo. Where can I find it?
> > >
> > >
> > > Mike
> 
> 
> Sorry but it appears as though the photo is gone.  I just checked 
> through both places and I can't find it so I must have deleted it.
> 
> Give it a try, you might be surprised as to how well it does 
work.  

> Keep in mind though, toner is plastic and if you wanted, you could 
> solder right through it.  However, in my tests, I printed out some 
> different size circles and soldered in the middle of them and 
> the "mask" seemed to contain the solder flow to that spot.
> 
> Chris
>

One of the most useful parts of this soldermask experiement is to make 
the most pro looking microstip antennas for 900 mhz thru 2.4 ghz 
around. Most prototyping shops do fairly rough work, with no files to 
hand the customer, i.e. my ex boss. So my goal is to be able to make a 
perfect pcb antenna and be able to hand over all the files to 
replicate them. That's where I start to hopefully make money so I can 
work from home doing fun stuff like this.

Mike