Homebrew PCBs

----- Original Message ----- 
From: "sciciora" <ciciora@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Friday, December 26, 2003 7:53 PM
Subject: [Homebrew_PCBs] Drilling before exposing, & how long is it
photosensitive?


> I just tried drilling a PCB before exposing it, and it didn't seem
> like a better method.  Spinning carbide drills at 30k rpm, the green
> photosensitive coating flaked off near the holes.  Just like sheering
> the boards before exposing them.  So, I think for the near future,
> I'll expose, develop, etch, _then_ drill.
>
> Does anyone know for how long they are photosensitive?

I find that the resist seems to go off after about six months. I just buy a
couple of sheets of the pre-sensitised material at a time, so that it's
always reasonably fresh.

 Are they
> still sensitive after develping?

It's probably a good idea to etch them fairly soon.

Do I have to etch in the dark?

Not for the ordinary stuff that is available.

Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html