Flexible and rigid-flexible printed circuit boards

Flexible printed circuit boards replace wires

Technological innovation of the kind we’re seeing in the medical sector or the automotive industry is mainly driven by the miniaturisation of electronic circuits. These days, a great many modern hearing aids, medical implants and LED car headlights make exacting demands of printed circuit boards, and require them to be installed in tiny spaces. AT&S can easily meet these demands by using flexible base materials. Flexible printed circuit boards can be bent or twisted during assembly, so they can be integrated into devices with almost any form factor and with space constraints. This is extremely important in devices like hearing aids and pacemakers.

Rigid-flex printed circuit boards combine the benefits of flexible PCBs and their rigid counterparts by integrating both bendable and rigid areas. This allows for cost-effective custom solutions for device manufacturers. A flexible base material can be used to connect two rigid areas instead of plugs and cables. This means that the signal pathways remain short and miniaturisation can go further than before. Such connections are also significantly more robust and are better at withstanding mechanical stress. Rigid-flex printed circuit boards are mainly used for systems in cars and in industry.

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These days, flexible printed circuit boards are used in all areas of electronics. They are usually bent, twisted or folded to fit into the product housing. Flexible PCBs are primarily used in place of wiring and plug connections or to create connections and configurations that would not be feasible with a rigid PCB.

AT&S manufactures flexible printed circuit boards mainly for the medical technology sector, where they are used in devices such as hearing aids and implants. The flexible installation options and high level of miniaturisation allow new functions to be added to such devices without increasing the size. For example, a modern hearing aid can now be connected to a doorbell, the TV or the wearer’s smartphone, thanks to the technology embedded in the compact design of a flexible PCB.

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The materials in semi-flexible printed circuit boards differ from those in flexible PCBs. A thin FR4 standard material can be used instead of the polyimide material used in flexible PCBs for a cost-effective alternative to “flex to install” applications. This FR4 material used limits the number of bending cycles and bending radius, but the material costs are lower than for fully flexible versions.

Because they make the most of the space available for a circuit, semi-flexible printed circuit boards are an especially appealing option in the automotive industry and for machine-to-machine communication, which is becoming increasingly important in industry.

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The requirements for the shape and design of printed circuit boards have changed since LEDs have started being used in the car industry and for building lighting. Flexible printed circuit boards can be affixed to an aluminium heat sink, for instance, and then fitted with LEDs for installation in front headlights. This makes the most of the available space while providing for superb heat dissipation.