Homebrew PCBs

On Mon, 15 Oct 2012 15:30:22 -0700, you wrote:

>Im a noob too ...
>
>I will be looking for FR4??or lighter copper clad board for SMD stuff ... 

FR4 is the type of material, not a thickness.  It's a bit more flame
resistant than FR3, for instance. 

Paper based boards are common in commercial equipment, while
fiberglass (and more exotic materials) are common in higher end
commercial and military.

Thickness of foil is measured in oz/sq foot.  1 oz is a common
standard, with 2 oz being considered heavy duty (high current) and 1/2
oz becoming somewhat of a new standard.

When copper is etched, it will undercut as the etching process
progresses, since the etchant can eat underneath the resist.

What is ideally a rectangle becomes a trapezoid.  When it becomes a
pyramid, there's nothing holding the copper to the board (or no copper
to be held), and the trace floats away.

so 1/2 oz or 1 oz is fine, typically 0.063 is thought of as a standard
thickness, while 0.033 will work for some applications, depending on
mechanical stress, size of parts, number of wires, and the like (also
kind of connector used to wire to the board).

1 oz will do a tqfp-100 pin IC with 0.5 mm spacing, which is
attainable with various methods.  You may wish to try something a
little less "picky" for a first attempt, though, as you get the
process tuned to your setup.

Harvey


>
>I don't know how thin copper can be put on fiberglass, but I will be looking for something that would be fairly easy to etch to hold stuff like pic32mx 100pin ic's ...
>
>Mike KC7NOA