two sided pcb tips?

[marc]

any advice, anecdotes, words of wisdom?
thank you,
marc.

[Mike Burgundy]

They're a pain to do yourself. Etching can be problematic since the majoity of home setups are horizontal (so the top is etched easily, but the bottom lags behind or doesn't do much at all). Photographic transfer of designs is more critical, you don't want too much UV going through the epoxy board exposing the other side. Lining up the connecting holes can be hard - a groundplane or ground/supply grid can be done, but anything more complex or demanding as far as positioning is concerned will be tough.
That said, it can be done. Not as good as pro boards by a long shot, but it can be done. I've used resistor lead clippings to connect top and bottom layers. I've also found that regular boards don't really suffer from UV exposure on the other side, as long as you don't use too strong a source. A 10 second flash from a 30W solarium worked ok on my boards. A 150W pro bulb in a local darkroom (used for silkscreening) bled through though.
Is it worth the pain? What are you planning?

[R.G.]

Advice and tips? Sure.

Don't do it unless there's no other way, or unless you will absolutely have them made by a commercial PCB production house. They're possible but quite difficult for a home PCB maker.

[Paul Perry (Frostwave)]

I had to do a double sided layout once (to proto somethig going into production) & being a cheapskate, I did two single sided boards & stuck them back to back.
Well, it worked... but, I havnt done it twice!
RG is right, plus all guitar fx can be laid out single sided, I think.

[marc]

thanks. i'm actually helping a friend who's designing an automatic stop action camera trigger. lord knows i tried to steer it to single sided, but noooo.
seriuosly though, thanks. i'll probably try the two boards aligned and glued together method. will post any succesful results.
marc

[R.G.]

If you absolutely have to do double sided,  do it as two single sided boards:

1. clean both sides of the double sided stock.
2. spray one side with colored lacquer; this will be the second side.
3.  image, etch and drill the other side.
4. strip off the etch resist; fine sand the lacquer side to flatten the drilling leftovers
5. clean in acetone or lacquer solvent, both sides
6. lacquer spray the side you've already etched, clean the second side
7. use the holes as a guide for aligning the image for the second side
8. image, etch the second side.
9. strip the etch resist and lacquer from the board.

The board should now have holes in all the pads, both sides.

PITA, ne est-ce pas?

[Paul Perry (Frostwave)]

Certainly, it was a PITA.
But, it did work!
just two single boards, poke wires thru the via holes, get the boards as close together as you can.
Not just a PITA, "butt ugly" as well!