Most optoelectric transducers use a Vertical Cavity Surface Emitting Laser Diodes (VCSEL) to convert optical signals into electrical signals. Due to the shape of these laser diodes, they must be mounted perpendicular to a reference plane. Using a flexible PCB makes it possible to assemble all the components on one surface and through the bending of the board bring the laser diode into the correct position.

As new materials are available, flex boards today easily achieve a high frequency signal integrity performance comparable to those obtained using ceramics in the past.