When design complexity, mechanical considerations or material selection requires one or more areas of the board to be a “true” rigid PCB but there is still a benefit in combining more than one board into a single unit, rigid-flex boards are the answer. It is the most reliable construction for mission critical devices and a requirement for many HDI components. Design, bare board manufacturability and assembly of these products require a bit of know-how that we share with our customers every day.
Built for reliability
The key to the reliability of any circuit board is the integrity of the barrel of the plated through holes and how materials with very different coefficients of thermal expansion behave through assembly and throughout the heat-cool cycles the holes will see during the life of the product. Just going from acrylic adhesive to “regular” epoxy is an improvement, choosing rigid materials with higher Tg and Td, matching CTEz values all the way to determining the best rigid/flex layer sequence… we can help you increase the reliability of your end product.
Materials and Stackups
Combining multiple materials in the same board is one of the advantages of rigid-flex construction. High speed, low loss materials, standard FR4 or rigid polyimide laminates can be combined with flex polyimide in the same structure to achieve the results your design is looking for. Bonded flex layers, loose leaf or book binder construction make a huge difference to the performance of the flex areas.
When your critical signals need to transfer from one PCB to the next there is no better transition than having no transition at all. No connectors, no expensive controlled impedance cables, no parasitic loss of inductance and capacitance, and with a bare minimum number of vias, the critical traces stay on the same flex copper layer and within the same stripline or microstrip structure from point A to point B.
Can it be done? How does it work? How long does the flex keep the shape? And, last but not least, how much does it cost? These are all design specific questions that we can help you answer for your product.