I bought some double sided PCB material on ebay that is apparently scraps from a firm in New Hampshire. All of the pieces areabout 3" by 6", are FR4, .060, but the copper seems really heavy. I peeled some off and it measures somewhere between .0065 and .004, depending on where I put the calipers. So, I'm thinking it must be at least 2 oz./sq. ft.

Or am I missing something?

Is there a better way to check the copper thickness?

 

Cut a piece of copper off the board and measure the difference in height instead of trying to measure the copper after it has been removed from the board and distorted.

 

Cut a piece of copper off the board and measure the difference in height instead of trying to measure the copper after it has been removed from the board and distorted.

I would have thought of that...eventually...maybe.

The bare board is .0550; the board with copper on both sides is .0605. Therefore, the copper is .0055 / 2 = .00275 on each side, which I think equates to 2 oz. per sq. ft.

 

do it the engineering way - cut a narrow strip, and get resistance (by measuring voltage drop when say 1A or whatever is going through it). knowing length and width of strip, one can get calculate thickness.

 

I would have thought of that...eventually...maybe.

The bare board is .0550; the board with copper on both sides is .0605. Therefore, the copper is .0055 / 2 = .00275 on each side, which I think equates to 2 oz. per sq. ft.

I communicated with the supplier, and he said that my measurements probably were wrong, because when I peeled up the copper, some of the substrate came up with it. He says he is almost certain that what I have is 1 oz.; he is sending some 1/2 oz. for me to try.

 

To do it properly you need an eddy current scope or x-ray flourescence or micro-sectioning/microscope

 

To do it properly you need an eddy current scope or x-ray flourescence or micro-sectioning/microscope

Sounds beyond my hobby budget.

 

Sounds beyond my hobby budget.

Then throw it in the trash because you have NO way of "properly" determining the thickness with "hobby" methods.

 

Etch the copper off a small offcut piece.
Measure both the etched & unetched pieces with a Micrometer (A Vernier Caliper is too imprecise).
You should be able to calculate it from there.

Or cut two identical sized sheets,etch one,then weigh them.
Knowing the area of the test sheets,the copper oz/sq ft can be calculated from the difference in mass.

 

I communicated with the supplier, and he said that my measurements probably were wrong, because when I peeled up the copper, some of the substrate came up with it. He says he is almost certain that what I have is 1 oz.; he is sending some 1/2 oz. for me to try.

Thanks for all the input.

 

None of this crude destruction! Use Van der Pauw's method to get the surface resistivity, and from that you should be able to calculate the copper thickness.

http://en.wikipedia.org/wiki/Van_der_Pauw_method