Homebrew PCBs

Zoran,

I don't know about screen printing resist. Perhaps others have tried?
(Crazy because not more than 10 feet from where I'm sitting is a 
complete screen printing setup. Not the film, though. We use the 
liquid and a curtain coater.) If I weren't so busy with machines, I 
might be able to answer your question.

But the real reason I'm writing is that it seems to me that the 
resist and etch part of making boards is kinda solved... Through 
holes too. 

It's the soldermask part that IMO needs addressed. Anybody have a 
GOOD DIY technique for soldermask? Can we screen print IT? (What 
material do we use?) By material I mean goop, not cloth.

I did see the testor's paint idea. But as someone else wrote, if you 
can solder "through it", it's not much of a solder mask is it<G> 
Maybe more of a conformal coating... 

Ballendo

P.S. I was really into the idea of inkjet printing resist direct 
until the question about two sided board registration came up, and I 
thought, "So much for that idea." Because I think it is going to be 
much harder than some have written to solve this with the standad 
feed of an inkjet.) I used to work on copiers, and even with the 
better quality of registration rollers and clutches used there; there 
is still a lot more variation than a reasonably "tight" 2-sided board 
would allow.

But it would seem a VERY good idea to try to determine whether the 
alignment needed for 2 sided boards is possible using the BEST case 
scenario first. Using paper and inkjet ink. Because if you can't do 
it with these, why would you expect that after... Changing the paper 
path, adjusting for board thickness, and printing onto metal
(the "slickness" factor), is gonna make it work better! 

It might be possible to do a soldermask that way though.(Since the 
registration needs are only one side at a time, and a bit looser 
overall.) Avecia has the material; it's just a matter of getting it 
in small quantities, and figuring out how to make it work with "SOHO" 
inkjets, as the inkjets it is designed for are the industrial HIGH 
$$$ types... Neither of these will be easy, IME.


--- In Homebrew_PCBs@yahoogroups.com, "Zoran A. Scepanovic" 
<zasto@y...> wrote:
> have you any thoughts on using photopolymer films used for 
silkscreen printing? I will try to obtain some samples and will post 
the results.