Brake pad delamination is one of the more serious pad failures: the friction material peels or breaks away from the steel backing plate it is bonded to. When it happens you can lose braking at that wheel. Here is what causes it and how to catch it.
What delamination is
A brake pad is friction material bonded and anchored to a steel backing plate. Delamination is the failure of that bond - the friction puck separates from the plate, leaving bare steel to contact the rotor. It is different from normal wear; the pad may still look thick but the material lifts off.
What causes it
The main causes are corrosion between the friction material and the plate (moisture creeping under the material, common with cheap or poorly-bonded pads), extreme overheating that breaks down the bonding resin, and manufacturing defects in low-quality pads. Rust-jacking - rust building under the material and pushing it off - is a frequent culprit on bargain pads with unprotected plates.
Warning signs
Watch for sudden severe braking noise (grinding or clunking), a chunk of pad material rattling or missing, uneven braking, or a piece of friction material found near the wheel. It can feel like a grinding brake that came on abruptly. Because it can happen fast, any sudden new grinding deserves immediate inspection.
Prevention and fix
Prevent delamination by buying quality pads with well-bonded, corrosion-protected backing plates, and replacing pads before they get old and rusty - see when to replace pads. If a pad delaminates, replace the pads as a set immediately and inspect the rotor for damage. Fit quality pads with fresh hardware.