Archive of the former Yahoo!Groups mailing list: Homebrew PCBs

----- Original Message -----
From: "mikezcnc" <eemikez@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Monday, January 12, 2004 4:34 PM
Subject: [Homebrew_PCBs] Anybody uses successfully a sun lamp?


> I am using a 275W Sun Lamp from GE, one of the kind that was used
> years ago to get a sun tan. It's 15 inches above the sandwich of
> positive PCB and 'flimsy' image. I tried times from seconds to 6
> minutes and each time, after having it developed in NaOH (5%) for 30s
> to 1 minute - there is no image left, all emulsion is gone. I've done
> so many tests that a test wedge method would become redundant. I
> think that since all image is gone that either the whole PCB is
> overexposed or the developer is too strong or a cobination of the
> two. Maybe you have some suggetsions. I also tried a laboratory clean
> NaOH and a new batch of PCBs- no change. The transfer method with its
> quirks of laminating, appears sweeter and sweeter.

That combination seems OK to me.

I use about 10 gm of NaOH per litre for developing, usual recommendation is
7 gm but I like it quite fast. It takes about 30 seconds.

It sounds as if your artwork isn't dense enough.

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