Hi Jerry,
I had the same experience as you. I'm an EE and do a lot of 1-off's
and proto-typing. Many years ago I tried Toner Transfer with special
paper and had very mediocre results. Several traces would always lift
and be damaged the the end product was very hobby looking. I switched
to the positive photo process with pre-sensitized boards. Kind of a
pain but always good results. After reading here, I tried TT again and
the results have been excellent. I rarely have a botched board and I
can easily handle 8/8 geometries (mils). I almost always do TT now
(thanks group!!!). I think paper is the big secret - I use the
Hammermill Office Gloss stuff (Hammermill OfficeOne Glossy Paper
#229030) with an iron and it works great. I've heard this has gone
extinct, my next choice would be Hammermill Color Laser Gloss Paper -
300 ct #292253 (Sams). I think this might be the same stuff with a new
name. It seems the secret is a thin light weight (cheap) glossy paper.
Usually called something like business gloss. I haven't tried this yet
but I just ordered a pack from Sam's Club to see what it's like.
Drilling is the big pain. I by the carbide bits from Jameco (#59 &
#75) and use a good drill press (I have an older Black & Decker from
when they were made in the US). It works quite well although the speed
should be higher for PCB's (I do have a small milling machine on my
x-mas list - hehe ... but yes, even the small ones are not cheap, $320
for the micro-mill from Harbor Freight). Someone here built a pretty
cool jig for holding a Dremel tool a while back. I'm sure it's in the
archives and I think there are even pictures of it uploaded.
One thing I did was switch to surface mounted parts where ever
possible. Once you get used to them, they're just as easy to work with
and the number of holes to drill goes way down ... usually just the
vias and a couple of connectors.
One other tip I like, When I'm done, I smear the whole board with a
little flux paste (harder to find but MCM still sells some), heavily
tin a large tip on the soldering iron, and drag it over the whole
board. Tins it up really nice in no time at all.
Phil
KA0HBG
--- In Homebrew_PCBs@yahoogroups.com, "jerrytr2.com" <jerry@...> wrote:
>
> Hello,
>
> My name is Jerry Kaidor. I've been messing with electronics for
> many many years. Also put in a 20-year stint as a firmware developer.
>
> The other day, I was doing a project with a PIC16F867A
> microcontroller. Built up the circuit on one of those proto boards
> that have a grid of three-hole lands. The resulting forest of little
> green wires did not inspire confidence. Neither did the smoke that
> came out when I powered it up :).
>
> So I decided that a PCB would be more appropriate. Found this
> group, read with interest about Toner Transfer. I had tried this
> about 10 years ago, it didn't work at that time. Like many things,
> the devil is in the details.
>
> This time, armed with better info, I downloaded the expressPCB
> software ( can't beat the price! ). I designed a one-sided board for
> my project and printed it onto a sheet of Epson photo paper that I
> had laying around. Found a gungy old piece of copper clad in the
> garage, spent about a half hour cleaning it off with 000 steel wool,
> paper towels, lacquer thinner, more paper towels, cosmetics buffs,
> etc etc. Transferred the printout with my wife's clothes iron.
> Wow! It came out perfect!
>
> The only problem ( and I realized this unfortunately when it was
> already mostly etched ) was that it was mirror imaged. I had used a
> function in my printer setup that causes the printer to print mirror-
> imaged - but apparently it wasn't needed. Grrr! OK, I'd just
> solder all the parts on the top :). Or just do it again...
>
> To play with the process, I started drilling holes. Hit a snag.
> My smallest "ordinary" drill bit was a #60. It was just too big. I
> also had some little tiny PCB drills that I got at the ham swap some
> years ago. Too small! (.8mm, I think )Also, chucked in my giant
> tabletop drill press, the tiny bit only lasted three holes before
> breaking.
>
> So - how does one drill these holes? I'll pick up an assortment
> of PCB drill bits today, but I don't think my giant drill press is
> going to work. Alternatives I see:
>
> ∗ Jameco lists a little drill and press for about $60.
> ∗ There is a Dremel drill press accessory for about $50.
> ∗ I have a Sherline milling machine. Sherline lists a "sensitive
> drilling attachment" that chucks into the mill. Basically,
> the mill only drives and holds the attachment - you move it up
> and down via a knurled ring. This really looks like a hot setup, but
> it's not cheap - $110.
>
> - Jerry Kaidor
>