Rigid-Flex hybrid PCBs

I know a lot of you have done OSH park for prototyping, and I’ve had good luck with them too, but I’d like to take a step into the hybrid PCB - flex and rigid, mostly because the space demands in the product(s) I’m prototyping make doing standard wire interconnects damn near impossible, and things get very crowded very fast.

Anybody done it?

My buddy Rory has done a bunch. If you have specific questions, lmk and I’ll pass them along.

They do rigid-flex at work, but they really try not to if possible. They are a huge pain in the ass. If you have any specific questions you can ask me as well and I will ask around at work.

Rigid flex as in it’s all flex circuit with some FR4 stiffeners, or truly hybrid?

I found this: http://www.flexiblecircuit.com/documents/Design-Guide.pdf which has certainly helped me out.

Main advantages of flex for me:

  • no time spent dicking with wiring harness

  • reduced weight in final prop (not so important for light painting but important for spinning and my target audience)

  • flex pcb will do better in a high impact, high abuse circuit (when these props are used for object manipulation (spinning) they tend to get dropped and abused quite a bit) - flex makes them more resilient.

Oh, and from an implementation level… how do you mark what’s flex, what’s stiff, etc in eagle prior to generating the gerber files?

The folks I know who do flex stuff don’t use Eagle… Rory designs PCBs for a company that makes industrial instrumentation.

I wouldn’t imagine they would. I’m learning a lot though about this process - I think that type-3 flex with stiffeners would probably be best for my application, so not a true rigid-flex hybrid. That PDF I linked does a pretty good job explaining things on the structural side, but I’m still not sure how to make it work in “whatever” EDA solution. I’ve definitely outgrown the free edition of Eagle, but it’s all I’ve ever used (all the way back to college from 98-02…)

I don’t think you’ll be able to order rigid-flex boards at reasonable prices in prototype quantities. Digikey sells FFC jumpers; with these you can use connectors or try hot-bar soldering to rigid boards. If you want your own flex circuit, gold phoenix has 100 sq in for $280 (http://www.goldphoenixpcb.com/singlepage.php?tg=specialprice), but you’re limited to 2 layers (I’ve never tried it, ymmv)

For the prototypes, that hot bar soldering on FFC jumpers might just be the ticket. In the longer term, this is a bigger pain in the ass than anticipated. Oh beloved EagleCAD, I must let thee go!