Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

Chris,

Funny, I've suspected that a while back myself. Mine was actually more
noticeable with doing "back-side" label transfers on some white
single-sided CEM-1(?), where I could really see that "cloth" texture.
I think I've gotten significant texture on the copper as well from
aggressively over-cleaning, or having to clean and re-transfer too
many times, maybe on boards with a lighter copper weight, also
probably with rougher abrasives rather than proper chemicals and finer
stuff. I'm trying to stay in the habit of being more careful there.

I've got an eighth inch piece of aluminum plate JBWeld'ed to my iron
for more consistent heat and flatness. For a long while, I've also
been meaning to cut a chunk of ply or particleboard that I could lay
on a bathroom scale on the kitchen counter, and do my transfers on it,
to get a better idea of the exact amount of pressure and time I was
using on the more successful attempts, but I haven't been etching much
lately.

I've gotten the little "speckles" of copper you mention too, but
didn't figure it was a substrate texture issue. I had guessed it was
more a sign of a good "even" etching which may have just needed a bit
more time, like the leftover stuff wasn't in the usual big, wide
"splotches", where the etchant hadn't moved enough or was too dirty.
Don't know much chemistry, but could there maybe somehow be tiny areas
where the copper composition isn't 100% consistent on our cheaper
board material, and takes longer to etch? FWIW, if they're large
enough and have enough surrounding blank space, you can sometimes
"sit" on them for a few seconds with the soldering iron and they'll
slide right off, sort of like those !%$#$ ∗!&#%$ small isolated pads
and holes that you actually 'want' on the board.

∗∗ Just noticed the aforementioned copper content suspicion in that
other reply, so I guess there's now a second "humble" opinion.∗∗

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.

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. ???

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.

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