PhotoPositive Boards - Any Tips?

[dpresley58]

I'm wanting to etch some boards and thought I'd try the photopositive approach. Anybody out there with some experience with these? I'd like to get some do's and don'ts about this material.

Seems to me with good artwork I could get some nice, tight traces...

[PurpleTheory]

Works great! That's how I do all of my pcbs now. Just make sure that your film positive is pressed securely against the pcb, I just sandwhich it between two pieces of glass, but I'm sure you could find some kind of holder made for that. I have a small UV light, but have had better luck with an ordinary light bulb.

Matt

[onboard]

Hey PurpleTheory, what would you figure is a typical exposure time for an average size (3.5" x 2.5" ?) board? Does light type make a difference, i.e. UV or white? How about a blacklight?

I'm curious about photo boards too -  if it's worth a two chemical process needing a developer besides your etchant of choice.  

Seems like six-of-one, half-a-dozen of the other with regard to steps involved - I guess the result is the proof of the pudding.

Meanwhile, back at the pad-per-hole ranch....

[gez]

Ton of stuff in the archives...

[Aharon]

Not worth the added effort and supplies if you ask me,much rather use PnP unless you are making very tightly spaced stuff which is not the case with effects.
You need the lights,the transparent stock,developer,etchant etc.
Aharon

[gez]

much rather use PnP unless you are making very tightly spaced stuff which is not the case with effects

That's exactly why I use this method, cram in as much as possible!  

[Aharon]

Yap,if you like small tolerances that' s the way to go
Aharon

[moving_electrons]

Works great! That's how I do all of my pcbs now. Just make sure that your film positive is pressed securely against the pcb, I just sandwhich it between two pieces of glass, but I'm sure you could find some kind of holder made for that. I have a small UV light, but have had better luck with an ordinary light bulb.

Matt

I printed on label stock and then stick it on the board per the instructions at Small Bear.  You have to make sure there are no big bubbles but small bubbles seem fine.

I exposed with a yard sale flourescent desk lamp.  Worked fine, but it needs to cool down before you use the developer, else all photoresist is removed.

Remember that the image you print is the mirror image of what you print for press and peel!  You can usually request a "mirror image" in the printers settings.

[onboard]

Ton of stuff in the archives...

I know, sorry. Got all giddy spurring Q&A and wasn't yearning for yet *another* lone slog through the archives...although then it ends up turning into yet *another* thread that's been covered ad nuaseum.

My wife's learning to gild, maybe I can turn out some hand gilded gold leaf PCB's. Talk about diy!  I can see the ad print - "Gold plate not good enough for your boutique analog gear? Try our gold leaf GCB's (gilded circuit boards)! Discreet payment plans available."