Re: gEDA-user: Copper for PCBs

[DJ Delorie <dj@xxxxxxxxxxx>]

> I'm looking at getting copper for homemade 2 sided boards.  Can
> someone tell me what positive coated sensitized copper clad is and
> how it differs from the uncoated?  Which is better (easier) for
> home-made?  Last question, it's been a while since I've really done
> pcbs, does the weight (1/2, 1, 2 or 4 oz) make a huge difference?
> Is that mainly about load?

Positive coated has a UV-sensitive plastic film layer already applied,
which is "postive" meaning "UV causes it to go away" so the print you
use has ink where you want copper to remain.

If you're not using a UV exposure setup, don't buy postive coated
boards.

With uncoated boards, you can use toner transfer, sharpies, press-on
stickers, or laminated UV film (negative, like I use - ink where you
want copper to etch away).  What you use and how you do it depends on
what kind of setup you have at home and what investment you've made in
the process.

I use 1/2oz mostly, because it etches faster and is less expensive.
Fabbed boards are normally 1oz (they start with 1/2 then plate on
another 1/2 when they do the vias).  2oz and higher are available for
higher current capability.

Thinner copper is also better for thinner traces.


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