Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, "soffee83" <soffee83@...> wrote:
>
> As Dennis suggests, I'd usually rather be safe and pull mine out 
early 
> if there are lots of areas (narrow traces in particular) which look 
to 
> be thoroughly etched already. I built a tank a while ago and it was 
a 
> night and day difference for uniform, "even" etching. Sad part is, 
> it's more trouble setting it up and cleaning it for the tiny PCB's 
I'm 
> usually making, and the heater and design of it requires me to use a 
> whole load of etchant each time, even for little stuff. I'm trying 
to 
> move to Sodium Persulfate, but with the FeCl3 I can re-use a giant 2 
> litre bottle of old crap with the heated tank and bubblers, but that 
> stuff's still a mess that I'd rather stay away from. When I finally 
> get some of that green Pulsar TRF, I'm going to try out the wipe-on 
> technique for the occasional "quickie" boards.

I built my own etching tank. Three times, in fact. The only things I 
did were A) make a huge mess everywhere and 2) find out that the 
copper etches too fast where the bubbles hit, causing horribly uneven 
etching. You may have a better design than the one I have, but I 
now use the etchant in a large sweater box (13 qt, #5 plastic) from 
Wal-mart, with a plastic sheet of acrylic to hold the 
board/brass/whatever face down. Four plastic feet made of cheap pen 
caps glued on, one side shorter than the other so it's a little 
tilted, a handle on the top that's not too tall to put the lid of the 
container back on. I made little plastic tabs as well so I can just 
slide the board in and out of the holder. Put directly in the sun, 
takes about two hours for a .005" thick piece of brass, less than that 
for PCBs. You could cover it with a black trash bag to retain more 
heat. Just make sure the thing doesn't dry out in the sun and crack - 
replace twice a year, depending. And 40 volume H2O2 from Sally Beauty 
supply works well to regenerate FeCl3. If you wanted to be picky, you 
could put it in a glass tray with sterno underneath to boil off as 
much water as possible, but I do a lot of etching and still haven't 
had to do this yet.

> Like Fenrir_co, I had my toner/iron techniques down to a science, 
and 
> somehow on my most recent etch, it seemed the toner demons were on 
me 
> with a vengeance. I'm still convinced that there's a reason for 
those 
> occurrences. In theory, it would seem that if you knew the exact 
> pressure and time you needed, and were doing a board which could 
more 
> or less fit entirely under the iron's base, the temperature would be 
> the only variable, and I'd guess there'd be a decent way to check 
that 
> somewhere. ???  

Don't forget that the metal shoe of an iron is not the actual area 
being heated, there are coils or rods inside that heat, causing uneven 
heating in the main plate. This doesn't matter for clothes, but is not 
even enough for PCBs, which is why you should move the iron around in 
order to try to hit the whole board with the correct temperature. 
However, the air bubbles under the transfer sheet are the bigger 
problem, once I figured this out and started cutting slits in the 
Press'n'Peel, the transfers improved to nearly 80-90% success. The 
pattern I use the most takes forever to cut out all the potential 'air 
pockets' so it's annoying, but works better.

> I'm getting more and more into that laminator idea, but I'm really 
not 
> into having to bump down to a thinner board for certain things, and 
> I've built up quite a supply of thick stock here already. I may look 
> for a heavier, used one, but I've got a $50 Staples gift certificate 
> from Christmas, plus they personally sent me a slightly "weaker" $5 
> one a while back for bitching them out in a letter about the alleged 
> "self-cancelling" rebate offer many of us tried to get after 
> Thanksgiving.

I did see in a few other posts around here that you /can/ put the 
.064" boards through the laminators if you put them in slightly 
angled, so it grabs a corner first. Just make sure it's got 
enough room so it's not going to hit the sides of the opening. Not 
sure how this would strain the laminator gears though.
 
> Just wondering (and being too lazy to search)-
> 
> What is the actual process on those laminator passes, do you make 
> multiple runs, and how do you know how many? Do you feed raw boards 
in 
> with just the photo paper on top, and are they indeed as effective 
> with the same paper we're all using for ironing, or do you have to 
> move to Press'N'Peel or something for 100% consistent results? Also, 
> are there specific details on what they all handle, or maybe a 
decent 
> list of what brand/model options they have for us weirdos who insist 
> on feeding "non-paper" items into the machines? (My 2-sided stuff 
was 
> something like .093!)
> 
> Thanks! (and sorry to slightly hijack the thread Chris)
> 
> George

I have used the laminator with both press'n'peel blue, and HP Glossy 
Laser Photo Paper. The only difference is that the press'n'peel is 
about 7.5x more expensive than the laser paper, but is about 7.5x 
easier to remove They both do perfect transfers with the laminator (I 
use the paper with a Xerox DocuColor 12 at staples - b/w copies are 
.06, while a $129.99 b/w laser printer would equal about 2150 copies 
at the store. Other than having to drive, which isn't often since I 
don't do much custom work, it isn't worth it for me to buy a laser), 
you just have to soak the laser paper in water with a little automatic 
dishwashing detergent and peel it off, then scrub off what's left with 
a Dobie (or other) non-scratch scuff sponge for teflon. Then rinse 
well. None of the toner came off any of my attempts. A few pinholes 
where the photocopy hadn't been 100% perfect. The Press'n'Peel also 
came off perfectly, with the advantage of not having any more work 
after that. Up to you how much you want to spend. I'm currently going 
to test a DocuColor 12 and a Xerox 1652 with Hammermill Laser Gloss 
paper, which is thinner than the HP and may come off with less 
scrubbing.

If I have time, I'll write up some information for the files area, 
though I do more custom brass engraving and etching than PCB 
development (I only do the PCB etching for friends or customers who 
want to experiment without having to set up chemicals). The general 
technique is pretty much exactly the same though.