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

----- Original Message -----
From: "Mike Putnam" <circuit@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, July 02, 2003 1:17 AM
Subject: Re: [Homebrew_PCBs] Pre-coated PCB stock shelf-life


>
>
> > It's a good idea to use the pre-coated PCB material fairly soon after
> buying
> > it, as the shelf-life is limited. I find I get rather poor results when
> > using stock much older than about six months. I tend to accumulate a lot
> of
> > odd-sized pieces of unknown vintage, so I need some sort of FIFO
> technique.
>
> Leon,
> Evidently it depends upon the chemical used to coat the boards. There are
> different chemicals and I cannot tell you what they are. However, I have
> always had a good quantity of stock on hand and when I stopped running the
> business, this caused me to have a lot of board stock that has been
sitting
> in my bin. I am now using stock that I purchased more than two years ago
and
> I am not seeing any differences in the way it etches or develops. All I
can
> tell you about the material is that it is the green coating and that I had
> the stock with the red tinted coating in the past and it did not last very
> long like what you have described.
> -Mike

Is your material negative-working? It looks as though that lasts longer than
the positive stuff I use.

Leon
--
Leon Heller, G1HSM
leon_heller@...
http://www.geocities.com/leon_heller