Homebrew PCBs

Hi guys,  that's not a silk screen, it's a mask.

A silkscreen is a mesh cloth (silk) that is stretched across a frame. It's coated with a rubbery plastic goo. The plastic is exposed and developed like film and when finished, the bare silk screen is exposed where ever you wanted copper traces. The silkscreen is placed over a copper board and an ink is squeegeed over the whole thing. The silk screen is lifted off and the ink now covers the copper traces. The ink is allowed to dry and the silk screen is washed out. After the ink dries, the board is etched. 

We used to do this in high school back in the 70's and 80's. The Graphic Arts students with their dark room would make the silk screens for us electronics students. It's good for low production medium resolution boards (low resolution by todays standards - it can do DIPs and probably .050 SOIC's).

The emulsion itself could possibly be applied directly to a copper board but I don't see how this is different than just going with a wet photo process that is already known to work.

Me, I'll stick with the toner transfer. Thanks to this group I have that one down solid :-).

Phil - KA0HBG


--- In Homebrew_PCBs@yahoogroups.com, "aurangzebhaque" <aurangzebhaque@...> wrote:
>
> Simao,
> 
> Thanks for the excellent link. I am going to try it this weekend.
> 
> One comment. I have been making many many silkscreens using translucent tracing paper, with the design pattern printed out on common laser printer. I have never had the problem of opacity in the printout, and edges etc. have always been satisfactorily sharp. We use the sunlight here because it is abundant and free ;-), and the rays are parallel. Maybe you should try it too. Hopefully it will save you money on film.
> 
> And thanks everybody for your inputs.
> 
> Aurangzeb
>