Homebrew PCBs

As Mike said the pro. shops do not use the office printers (Laser or ink
jet) to make the artwork. In fact the artwork my favorite board shop
uses is a light red and it's easy to read newspaper through it in the
"dark areas"...

I've been using my HP LaserJet 1100 for some time now and have none of
the problems described here and elsewhere in this thread.
Using Apollo CG7060 I am able to do 5 mil lines all day long.

As far as I'm concerned the quest for absolute blackness is a non issue.
A simple test is to place a sheet of white paper with regular black text

under the "dark areas" and in good room lighting you should not be able
to read the text, if that test is OK, then holding a transparency up to
a strong room light you will
see light through it as a "grey" area.

The real trick is exposure. Get to know your light source and always use
the same distance between lamp and  artwork.
I use GE 500W bulbs at a distance of 6 inches and expose for 70-90
seconds.
I work in normal room lighting and during day time simply close the
blinds, no need to "darkrooms"
As you see here it's Texas daylight outside and the board exposure came
out perfect. http://hans-w.com/setupforexposure.jpg
I then develop in a mixture of household Lye (caustic soda and other
fancy names) for about 30-45 seconds. I re-use the Lye, no need to throw
it away, my current mixture is a dark green from developing many boards
and is at least 9 months old.

It works every time, and has done so for many many years...it  never
fails.

As far as scaling goes, I figured out a long time ago, when I mirrored
the one side to get the emulsion close to the board, it always
came out at a different scale.

As most of my home made board are small I have never had a problem with
scale. For a while I used my CNC mill to drill the board before exposing
the two side (at the same time). If scale had been wrong then the CNC
mill using converted Excellon file would have been wrong also.... it
never became an issue.
For the most part I find it's faster to use my Dremel drill in a Dremel
drill stand and am able to drill 16 mil holes without breaking the bits,
I can't do 16 mil by hand...breaks every time :-)

Hans W



Adam Seychell wrote:

>  I've seen many poor prints from inkjets too. The trick is to use
> the corrct ink/printer and transparency combination. The
> differences between the worst and the best is incredible.
>
>


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