PNP Blue, also Dril Microscop

[R.G. Keen]

>Do you know if it's possible to run traces between pins?
Emphatically, yes. I use this stuff all the time. With Easytrax, you
can -* reliably and repeatably *- run 12 or 15 mil traces between IC 
pads. 

The limitations of Press-N-Peel are about 10mil traces, and a practical 
board size limit of about 6-8 inches in any dimension, because of the 
non-uniform thermal expansion of the plastic substrate material under 
hand ironing. I suspect that one could tinker with a hot-shoe office
laminating machine and get perfect -* and repeatable *- results over
a full sheet. In fact, with a reliable and adjustable hot roller
machine, I don't see why one couldn't set up a pc board shop where you
charged LESS for small quantities, as the most economical quantity to
manufacture would be one.

There is a limitation on using this in a board shop, I guess, in that
you cannot guarantee absolute accuracy because of the thermal
expansion, and that would hose up CNC drill machines. You'd have to use
a drill microscope to do the drilling.

Speaking of which, I just completed my home-grown drill microscope. 

To build a drill microscope, get a Dremel tool and the accessory drill
press stand. Dissasemble the drill stand to the Dremel holder, post,
and mounting plate. Figure some way to mount the post vertically, as 
you'll need the base. I had an old base, so this was not a problem. 

Use the Dremel and the sanding drum tool to sand away the post stop in
the post mounting hole in the base, so you can place the base on the
post and slide it up and down to any position. 

Mount the post vertically. Mount the Dremel holder with the Dremel
pointing UP. Slide the base onto the post, flat side up, down to where
you can just raise the Dremel chuck into the hole by pulling the lever.

Buy a Tasco 4x20mm rifle scope (mine was $17 at the local sporting
goods store) and a 3x jeweler's loupe ($5) place the loupe over the 
objective (non-eyepiece) end of the scope. You should now have a 12x
microscope that focuses to 2" and has crosshairs in the center.

Figure out a way to mount the scope onto the post, so it points directly
down the bore of the Dremel chuck. I used blocks of nylon drilled to
just accept the post and the scope, split, and with a tightening screw, 
and held together with a 1/4" steel rod, also adjustable.

I can now align the scope crosshairs on the point of an 0.032" drill, 
slide in an etched printed circuit board and accurately drill out 
the center of the pads.  Fast.


>On Tue, 10 Dec 1996, Bob Zimmer wrote:>

>> As mentioned in a previous post, I had emailed the vendor Techniks
>> (http://chelsea-ios.com/~techniks/) for a sample sheet and found it to work
>> just as I wished it would.
>> 
>> I used EasyTrax to print the PCB layout on a piece of paper, cut the full
>> sheet into a sheet about 1" larger than the needed size in both directions
>> and taped it over the layout.  I then ran that through the laser printer (my
>> old HP IIP) reprinting the image on to the PNP sheet.  Cleaned the board
>> with a scouring pad, ironed it onto the board, positioned just between the
>> first two steam settings and got nearly a perfect image. I lost only a small
>> portion of the board edge outline!
>> 
>> By cutting the sheet down, I should be able to make 4 boards from each
>> sheet.  I had ordered a number of blank double sided boards from Electronic
>> Goldmine.  QTY 10 for 4x5" boards was about $.80 each!
>> 
>> I later tried another board and again got perfectly usable results!
>> 
>> Called them up and just ordered 40 sheets ($50.00)!  Should be set for a
>> long time!
>> 
>> This makes the cost per board (not including time and etchant) at about
>> $1.15 each.  Only downside that I can see is having to completely etch the
>> copper off the second side as I'm only doing single sided.
>> 
>> This beats anything I've ever used before!
>> 
>> Bob