PCB making tips

[R.G. Keen]

>Now the tip how to make PCB's. I haven't actually tried this,
>but I was just reading sfnet.harrastus.elektroniikka newsgroup
>(don't try it unless you've got some training in Finnish language).
>There was one guy who had tried everything, and he found that
>self-adhesive adressing label sheets, or actually the slippery
>paper on the back, gave the best results, much better than TEC100
>or PnP blue, almost as good as photocopied pcb's. Got to try
>find some sheets and test this method.
These do work, as the siliconized surface holds the toner only
tenuously. However, the hold of the toner to the sheet is so slight
that you essentially have to process the PCB as soon as you print the
sheet. Anything else and some parts of the toner rub off the sheet with
handling. You have to be more careful as the lines get finer and the
handling longer. 

The PNP blue is far preferable to TEC100, and is much tougher than 
the addressing label sheet, as the toner will not rub off as easily. 
I have made PCB's with PNP blue sheets that have been in a file folder 
for six months or more and had excellent results. 


I'll reproduce here the biggest tip of all in making PCB's - make
yourself a drill microscope. Drilling is by far worse than imaging and
etching.

Get a Dremel Moto-tool ($40), carbide PCB bits ($5), a Dremel drill
press accessory ($40), a Tasco 7x20 rifle scope, 1/2" plywood, and 
a 3x or 5x plastic jeweler's loupe. 

Make a small stand of about 12" by 12" out of plywood or chipboard. 

Screw the bottom plate of the drill press accessory to
the top surface of the plywood, mark where the back post and center
hole rest over the plywood, then remove the plate. Drill out clearance
holes for the post and the drill end of the moto-tool in the plywood.

Screw the plate back on top of the plywood, then insert the back post 
through the plate and plywood so there is enough post on the bottom of
the plywood to attach the Moto-tool holder under the plywood pointing
up through the center hole in the plywood and plate. 

Using some 1/2"
plywood and automotive type hose clamps, make a holder to attach the
rifle scope to the portion of the back post that protrudes on top,
positioning the scope so the crosshairs can be adjusted to look down
through the center of the center hole at the drill bit. Tape the
jeweler's loupe to the objective end of the scope to correct the focus
to about 2".

Now put a drill bit in the Moto-tool, align the scope to point directly
into the center of the bit. Tighten everything down so it doesn't move. 

You can now put an etched PCB on the plate, center up a pad in the
crosshairs, and drill UP FROM THE BOTTOM in the exact center. 

This is a lot of trouble, granted, but once you do this once, you'll
never drill a PCB the ordinary way again. 0.028" holes are easy, and
you don't break carbide bits - which now last for throusands of holes.