SO WHAT ARE PADS MADE OF?
Generalizing, cheap brake pad makers use either processed rubber or forms of resin, which provide adequate and silent braking under normal loads. These pads generally have shorter lifespan, especially under wet conditions.
Semi-metallic pads use a combination of synthetics and different proportions of various metallic particles for the pad compound.
Metallic disc pads use sintered steel with no synthetic additives. They transfer quite high frictional loads to your disc rotors which results in higher heat load and surface wear.
You will also see “Ceramic pads” in the market which sound very exotic and usually cost more. They are made using a mixture of clay and porcelain with copper filaments used as a binding agent.