Brake pads are subjected to huge pressures from the caliper pistons in unequal proportions across the pad. The back plate must remain flat to offer optimal performance so PBS use Nucap NRS hooked back plates so there is a mechanical and adhesive bond between the pad material and back plate.
When brake pads run at high temperatures, gases can be created by the pad and can cause layer between the pad and brake disc. This can make the driver feel like they have lost performance as the brake pedal feels the same but the car will not stop as normal, this is called fade. A slot is cut into all PBS pads to offer the gasses a route to escape.