PCB material question

Community PCB Design
1

I am looking for a PCB material that will be stronger than FR-4. The board will be credit card size, but .010 thick. FR-4 twists enough to release component connections. Is there anything stiffer that is also resilient (not brittle) too? Ceramic is stiff, but will break easily. It will be for RF use, so a metal backing is not an option.

Thanks,

Ron

2

What’s causing that sort of force? Proper mechanical design should prevent those problems.

3

leon_heller:
What’s causing that sort of force? Proper mechanical design should prevent those problems.

Proper mechanical design goes out the window at .95mm thickness in a back pocket. Think about the force an average credit card goes through. I am making a really, really, smart card…

4

I think your best bet would to use a flex PCB affixed to a sheet of hard plastic. Just let it flex.

5

If the FR4 only flexes, and you are able to put all of your components on a single side, then gluing/epoxying another blank sheet of FR4 to the back should be a perfect fix. It would also provide a perfect ground plane if that was called for in the design.

There are different thicknesses of FR4 as well; perhaps a thicker board would be worth a look.

6

reklipz:
If the FR4 only flexes, and you are able to put all of your components on a single side, then gluing/epoxying another blank sheet of FR4 to the back should be a perfect fix. It would also provide a perfect ground plane if that was called for in the design.

There are different thicknesses of FR4 as well; perhaps a thicker board would be worth a look.

Max thickness is .95mm including components and battery.

7

I think Mark’s suggestion of a flex PCB, with stiffener concentrated under the components is probably the way to go. That way, when the whole PCB is flexed, the area under the components is flexed the least.

I’m not sure that you can go much stiffer without going to a ceramic substrate (which it seems is not really suitable, due to brittleness). I’ve never heard of it being used for this before, but you may be able to make a Zylon-epoxy composite that is somewhat stiffer than fiberglass, but I expect the improvement will be minimal. Zylon is an insulator, but is stiffer than carbon fiber:

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

Soller Composites used to stock Zylon fabric, but I can’t see it anymore:

http://www.sollercomposites.com/