Homebrew PCBs

Chris,
I've done a lot of tests and found the following transparencies to work
well
3M CG3300 is good down to 10 mil
Appolo CG7060 does 5 mil all the time.

I understand what people say about LaserJet not doing well on large
surface areas. I can see through the large areas and at first ( many
years ago) I used to worry about it.
The first thing to check is the printer settings. I found HP had a
setting for "Economy Printing" and it defaults to that every time.
I simply goto the setting box and uncheck that feature and print at
600dpi
The next step is exposure, as you can see in the photos I use two 500W
GE lamps at about 6 inches. Exposure time is 70 Seconds.
I develop using Lye (in U.S.A. Red Devil Lye) at a mixture that gives me
clear visible copper in about 60-90 seconds.
During Developing it is possible to remove the board from the Lye and
rinse it in clear water, inspect with magnifier and if there is still a
trace of resist simply put it back in the Lye and continue developing.
This works every time. I reuse the Lye and it lasts for months and
months in a TupperWare container. My Ferric Chloride is about 6-7 years
old and still going strong.
Example ( I posted before) http://hans-w.com/pcb_harwin_rivets.jpg which
also shows Harwin pins and how I rivet them, notice the large surafce
area is solid and not pitted.
I use CoolAmp silver plating powder to coat the boards, this is cheap on
a per board basis, but will cost about $50 to get started, 1/4lb jar of
it.
A 1/4lb jar lasts a long long time. There is a product called something
like Tin-It, I've tried it, and it's a mess. It does not last long after
mixing and therefore becomes expensive on a per board basis.

Best Regards
Hans Wedemeyer

Chris Graham wrote:

>  Hans Wedemeyer wrote:
>
> > I make double side board all the time. I used to do it the way you
> > mentioned, and even wrote a program  for my CNC mill to compensate
> for
> > alignment problems.
> > I found a better way by printing on transparencies and then aligning
>
> > them visually, then stapling them together. Then slide the board in
> > between the transparencies and sandwich the whole lot between two
> plates
> > of glass, and place the sandwich between two lamps
>
> I make boards almost exactly the same way, also using Eagle.  I print
> with a
> Brother 5040 laser printer at 1200 dpi on overhead transparency
> slides.
> I've made double sided boards down to 10 mil traces.
>
> I decided to go with Eagle (even though I don't really like its user
> interface because of) its stability,  the extensive parts libraries,
> and the
> very active support and user forums.  Even if I don't find the exact
> part I
> want in an Eagle library I can usually find something close that I can
> start
> with - much easier than starting from scratch on a new part. And if I
> have a
> question or problem I've always been able to get a quick answer on one
> of
> the forums.
>
> Regarding printing transparencies, one minor irritation I'd like to
> overcome
> is that dark areas on the slides aren't as opaque as I'd like, and
> I've
> needed to double up the top and bottom transparencies, for a stack of
> four,
> which is a little tricky to align and keep aligned.
>
> What media do other people print slides on?
>
> Also, I read somewhere of someone who printed "transparencies" on
> normal
> paper and then made them more transparent by spraying them with some
> solution (maybe spray silicone?).  These resulted in very opaque dark
> areas.
> They needed somewhat longer than normal exposures, but produced
> excellent
> boards.  I now can't find where I read this, and would love to know
> the
> details of the process.  Are any of you familiar with this?
>
> - Chris Graham
>
>
>
>                    Yahoo! Groups Sponsor


>
> Be sure to visit the group home and check for new Bookmarks and files:
>
> http://groups.yahoo.com/group/Homebrew_PCBs
>
> To unsubscribe from this group, send an email to:
> Homebrew_PCBs-unsubscribe@yahoogroups.com
>
>
>
> Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.


[Non-text portions of this message have been removed]