--- In
Homebrew_PCBs@yahoogroups.com, Chris Maness <chris@...> wrote:
>
> What is the minimum pad size (in mils) for home made PC boards? (Single
> Sided).
>
> Thanks,
> Chris Maness
>
>
> [Non-text portions of this message have been removed]
>
I drill the holes first then laminate dry film resist. UV expose with a film negative, develop the image, etch and strip the photo resist. The copper pad is never stressed this way and very small annular rings are possible. The only problem will be the weak copper adhesion with such a small copper area. Any component movement and the copper bond will break. With all of that in mind, it's best to use a larger annular ring on single sided boards. Most of my designs are surface mount and single sided but any through holes are allowed at least .020" around the hole and more if possible.