Another tip: concerning the tedious process of drilling, it won't be as
rugged as properly drilling the holes, but you can always try to surface
mount your components. That is, you could bend the prongs on your 40 pin
dip so that they lay flat on the board and then just solder 'em on.
Sent from my iPad
On 2012-03-05, at 4:58 PM, Harvey White <madyn@...> wrote:
On Mon, 05 Mar 2012 20:24:16 -0000, you wrote:
>This has become a humpling experience!
>You folks have made this sound too easy, or maybe senility has set in on
my part.
>
>First try: Printed a sample from some packages example, magazine paper, HP
P1102W Laser printer. Not too bad, did not fuse well to board though.
Either board not clean enough or not enough heat, unless there's a
problem with the magazine paper.
>I used really thin double sided board, Electronic Goldmine vendor , I
think.
>Second try:This time I ordered paper from DigiKey. Made a board with
DesignSpark PCB package. It is pretty simple, just cross over from an
Arduino to a prototype board with SIP's & some RJ-45 Female connectors to
SIP's to stick on a Prototype Board. All on about a 3X5 paper. I used a
Double sided board that I had in my junk. Washed in Lacquer thinner,
polished with scotch brite pad.
I'd have used the scotch brite first (I use Bon-ami, then 1200 grit
sandpaper, then acetone). I've also tried right on a dirty board, and
it works surprisingly well.
>Toner did not transfer well and that is where I disvovered I had not
properly scaled the paper. The pin spacing was 9 to the inch instead of
ten. OK, so I washed the toner off with Lacquer thinner and went to my
giant Chinese milling machine to check out drilling the board. I set the
800 pound machine up to run at max spindle speed knowing it would not be
fast enough. How about that! The 1 mm drill with the bigger shank did jus
fine with it!
>after drilling 40 pins for a DIP chip I realized computer control was
going to be essential. Project under planning...
Know that one. I still suspect not enough heat.
>The chip fit fine but I wonder about the drill size. It may be too big to
leave enough copper for pads. IS 1 mm THE RIGHT SIZE FOR PC BOARDS GENERAL
USE?
Nope. I use #70 for 1/4 watt resistors, #68 for slightly larger
parts, #62 or so for dips, and larger drills for things like switches,
stake in terminals, and the like.
In general, I try to match the size of the drill to the lead. I'll
drill a hole and see if it works well enough, then reserve that size.
make the pad suitably large (larger than stock, for example, for hand
soldering).
>
>Third try: I got the scaling right and tried again with some single sided
board that I had in my treasure collection. I figured that I needed more
heat so I cranked up the heat on the iron to Linen. I did not move it
around much but I did push down pretty hard. After about 3 or 4 minutes I
heard a "pop" sound and figured I had broke something in the iron. As the
paper cooled down it turned kind of brittle.
Too hot.
>The board bowed away a bit and the stiff paper raised up in spots. I put
the paper in a soak bucket and did something else for a bit. When the paper
separated not only had the fusing failed to transfer well but the PC board
had copper blisters large and all over! I blame the board this time. It was
likely over 30 years old.
You're supposed to make the toner tacky, not liquid. Too much heat
can melt the epoxy, which it sounds like you did. Have you considered
a GBC creative laminator? Mine works well enough for thin boards, but
I do run through 6 to 8 times. (say 4 up and 4 down),
>
>Fourth try: I ordered some fresh, modern board from Jameco. It did not
blister, but did not transfer as well as expected. I think the single side
board is going to bow any way I do it I am thinking I need to just use
double sided and etch the excess away. Maybe I need to try some different
paper too.
I use thin (0.023) board. It does bow after all of the processing,
but when epoxied together, and pressed flat, stays remarkably flat.
It does not bow badly.
>
>Comments, criticism and laughter invited...
I think you're overdoing a bit of the heating. Irons are not optimal,
and laminators seem to be much better. Good arguments have been put
forth for not using Tshirt presses.
Harvey
>
>John Ferrell W8CCW
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