February: FR4 Flex technology

What's the FR4 Flex technology?

FR4 Flex PCBs are rigid PCBs which are made bendable by means of a specially controlled deep routing process. The bending area is protected by a flexible solder mask instead of a standard resist. This flexible solder mask covers the copper traces without the generation of any cracks over life time. The bending area of the FR4 flex board can feature up to three electrical layers and can bend at angles from >0° to 180°.


Where is the FR4 Flex technology utilized?

When construction space is limited to two dimensions, the FR4 Flex technology is offering a third dimension for the PCB design. For instance in many present electronic control units the contact area of multi-pin connectors is folded away by e.g. 90° to free up precious PCB area for other components. Generally FR4 Flex PCBs can be considered when construction space is prohibiting the use of a single rigid PCB and multiple bending cycles are not required.


What's the cost of FR4 Flex compared to rigid flex PCBs using polyimide foil?

In comparison with rigid-flex PCBs with polyimide foil FR4 Flex is offering a distinct cost advantage. Depending on the lay-up savings of 30 to 50% are feasible. Moreover, process cost reductions are achievable since a pre-bake process is not required any longer.


Is FR4 Flex qualified according to automotive requirements?

Yes, SCHWEIZER's FR4 Flex boards have been used for more than 15 years in automotive applications. More than 50 active parts with up to three electric layers in the bending area are currently manufactured for automotive customers. Among these are parts used in high-temperature environment or for safety critical applications.


How often can an FR4 Flex PCB from SCHWEIZER be bended and at what maximum bending angles?

SCHWEIZER has developed dedicated test equipment for the qualification of the FR4 technology. In extensive test series a specification of maximum bending angles and the maximum number of bending cycles have been determined. Those values vary depending on base material combinations, prepreg type, thickness of copper cladding and mission profile. Send us your PCB data including information on bending area and bending angle. Please contact us. We will find an appropriate solution also for your 3D challenge.