Another Wacky Idea for Making Circuit Boards Part 2

I suspect the resolution would be very poor. Put a thin piece of frosty mylar or paper on your monitor... the image is pretty blurry. And the LCD polarizers and such may not work for UV.

John

John Larkin a écrit :

UVs will toast them pretty quickly.

D, why so much energy wasted in wacking ideas when today you just have to provide some low cost PCB mfr with gerbers and let them work. Just get real. Oh, I can see some thread about a wacky idea on how to glue excel to some video player and hack your own CAD program. Then you just have to build a CNC drill, hacking an old sewing machine with some old printer stepper motors...

Oh bummer :(

It's just that I'm always changing my designs (f*ck ups) and my PCB volume is like 20 boards/year.. I think I've never duplicated a PCB yet.. I have one PCB where I did so many design changes that if someone copies the design ..that's a laughable amount of useless electronics that I just isolated instead of removing..

So I don't mind DIY PCB fab for now.. Let's me get stuff done on the weekend when PCB fab houses are closed. :)

By the way.. I've ordered dry film photoresist to play with for the 1st time. :) D from BC

prolly not... maybe you could use the optics from a laser printer instead... dunno what wavelength they use or if visible light photoresist is available.

Bye. Jasen

I'd expect the liquid cristals to absorb ultraviolet at which the chemical bonds may even break. As Fred put it : The UV will toast the liquid cristals.

A simple solution is to use an polyester foil in the printer. I prefer the laser, but a colleague successfully applied an ink jet too. Just make sure to have the top layer mirrored, such that the ink is right on the photosensitive copper surface.

Rene

D from BC wrote in news: snipped-for-privacy@4ax.com:

You can BUY cheap battery powered small fluorescents at Lowes,WalMart,Home Depot,for ~$10,some also use 12V AC adapters. (I use them for emergency lighting in blackouts)

Then get a UV sterilizing tube for it,leave the cover off. I used to use one for erasing EPROMs.

It sounds like you'd do better investing energy in getting it right the first time, instead of finding a speedier way to iterate mistakes.

Most of the things we design are sellable as Rev A, the first board, and we don't prototype. As complexity and density and board layers go up, time spent checking really starts to pay off.

John

D from BC wrote in news: snipped-for-privacy@4ax.com:

Might not work.

If a fab house were to do it optically, they'd use mylar sheets with the pattern printed on to do a silkscreen, which they'd use to screen etch resist or powered/liquid conductors on a PCB.

For one off optical, they could use the mylar sheet, or a transparency from laser or a plotter.

Nobody I know of screens boards these days. The bare copperclad board is cleaned and roller-laminated with a dry resist. The board is sandwiched with the artwork film and exposed to UV, which sensitizes (actually polymerizes) the resist. The resist is then "developed", which removes the unpolymerized areas of resist. Then the copper is etched.

I suppose some people still use liquid/baked-on resist, but the process is pretty much the same.

Silkscreens have very bad resolution, so could be used only for very crude boards.

I wonder if any direct laser-scan exposure is being done, to eliminate the film.

John

I think I've seen UV lasers in my internet travels.

I'd be happy with a slow moving low power laser on an XY plotter or CNC :)

My optics are crappy..but I think it'll work. The PCB copper might need to be buffed to a mirror finish before the photoresist is put on. D from BC

Selected by John Bordynuik "Nobody I know of screens boards these days. The bare copperclad board is cleaned and roller-laminated with a dry resist. The board is sandwiched with the artwork film and exposed to UV, which sensitizes (actually polymerizes) the resist. The resist is then "developed", which removes the unpolymerized areas of resist. Then the copper is etched."

I see many automotive single and double-sided board manufacturers still use silk-screening. In fact, a shop I was at a couple of weeks ago is continuing to use it on flex circuits. Screening has improved much....

P.S. I wouldn't use it - photo is better but more expensive.

Regards,

John Bordynuik CPU Architect JBI

Long ago I tried to find silk screen...screen material...another GoogleFu battle that I lost.. :( D from BC

doh! :o

What's some good keywords to find that stuff? silk screen screen? printing screen? screen for printing?

"I scream for silk screen" :P D from BC

?? You just have to know that silk screens are not made from silk.

;-)

Best regards, Spehro Pefhany