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Subject: Re: [Homebrew_PCBs] Re: A $500.00 "UV" non-trivial exposure box.....

From: Russell Shaw <rjshaw@...>
Date: 2005-11-18

lcdpublishing wrote:
> ANother thought I had about using the photo-resist boards was the
> potential for another problem that I don't know if there is a work
> around or not.
>
> If you expose a board and the exposure doesn't work out as planed,
> it is then ruined isn't it?

If you haven't developed it, you can expose it more if you align
the printout again with what you can see on the resist.

> For example, with toner transfer, if it turns out bad, a missing or
> pitted traces or whatever else can go wrong, I wash off the toner
> and do it again and again till it is good enough for what I need.
> The only loss I have is time and paper.
>
> However, from an ignorant point of view ( I have never tried this
> process), if something goes wrong, the board can't be used again in
> the potoresist process can it?

Not after developing. However, you can scrape bits of resist
off with a scriber and add bits with a resist pen.

> Also, as I don't know what things look like along the way, can you
> see the traces with the resist on them after developing? If so,
> what does the developed photoresist look like?

Undeveloped, the patterns look slightly lighter or darker than
unexposed areas. When developed, you can see the copper.