I want to share my recent PCB experience:
I find the best low cost setup for me is:
1) Eagle light free software (I use in XP, but since I had to make most
of the library devices by hand, I think I may try "PCB" on Linux when I
move to open source only)
2) ink jet transparacy sheets (I make the transparancy bigger than the
PCB so there are no shadow lines)
3) Epson 2400 dpi inkjet (have to set on best print for small SMT pins)
4) florescent desk lamp
5) plate of glass or plexiglass (plexi is not as heavy and may require
books on both sides when under lamp)
6) Presensitized PCB (I found lower cost from web-tronics.com for 1 oz,
digikey.com also has these in 4 oz)
7) Posdev developer (from web-tronics.com)
8) ammonium sulfate (I have not tried FeCl yet, but I am sure that is ok
too) for etching - (I was using 2 sealed plastic sandwich baggies in an
old pot filled with water on an electric stove set at warm for good
results, but bought the thin $40 etch tank from web-tronics - the ethant
is not as hot and takes more time but does still work)
9) tin coasting (again from web-tronics, used in a few plastic bags in a
pot with water over hot heat on electric stove - I was amazed the first
time I did this, a nice silvery tin coating only took minutes)
One thing I found is that the developer may have caused some irritation
on my hand and so now I use cheap nitrine plastic gloves from
harbor-freight, and that the leaving the ammonium sulfate exposed to the
open air for more than a few hours can cause minor eye irritation, and
did cause minor stomach nausia in a different person. I found that I
had to experiment to find the best exposure time, and developer
mixture. I am at a conservative 25 minutes exposure (each side), 2
liters room temperature water and ~ 1/4 cup developer). I think that I
could possibly be more efficient with 15 minute exposure, 1 liter warm
water and 1/4 cup developer. For etching I felt that I had to keep
adding Ammonium Sulfate powder for each board to get the etching going
faster. In any event, developing should only take 5 minutes and etching
should take near 15 minutes, any longer and the mixture is not correct.
Before exposing, for a 2 side board, I drill 4 orientation holes (vias
in the circuit) in the 4 corners in order to align the bottom and top
transparacies.
Ted
mikezcnc wrote:
> MikeZ_Photo_Etching in files section show my latest progress in Photo
>
> Etching. In reality, the PCBs look perfect and very expensive.
>
> Gentlemen, I appreciate your help in guiding me thru the maze of Heat
> Transfer and Photoetching and I feel being very profficient and 100%
> reliable in both methods.
>
> In 30 minutes I can have a PCB etched and dry ready for soldering for
> the cost of a PCB plus few pennies. I am not making it up.
>
> Which conveniently brings me to the next question: where in US is the
> cheapest source of PCBs? Mike
>
> PS I despise the use of special paper at $1.50 or $1 a piece.
>
>
>
>
>
> Be sure to visit the group home and check for new Bookmarks and files:
>
> http://groups.yahoo.com/group/Homebrew_PCBs
>
>
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--
Ted Huntington
Programmer Analyst I
Main Library
University of California, Irvine
PO Box 19557
Irvine, CA 92623-9557
emesgs:
thunting@...web page:
http://business.lib.uci.edu/webpages/ted.htm8:00a-12:00p Business Office (949) 824-8926
1:00p-5:00p Multimedia Resource Center (949) 824-1674
"Stop violence, teach science."
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