Today’s brake pad formulations continue to evolve, but the basics include organic, non-asbestos organic (NAO), semi-metallic and ceramic.
Organic pads (even today, some aftermarket pads may still contain a degree of asbestos) contain less than 20% metallic content, so they’re easy on rotors, are relatively quiet and perform best at lower temperatures.
NAO pads are made using so-called organic materials such as fiberglass, Kevlar and a host of other materials. Like organic pads, they’re relatively soft and quiet, but the wear rate is low and they create plenty of brake dust. They can include small levels of metals (copper, steel) to help with heat transfer.
Semi-metallic pads contain approximately 30% to 65% metal and are tougher. They last longer and perform better at higher temperatures, but they’re relatively aggressive and can wear rotors faster.
Brake pads that are touted as ceramic are not made of 100% ceramic. Rather, the compound is comprised of ceramic fibers/powders and manufacturer-specific binding and filler materials, often instead of the steel fibers used in semi-metallic pads. The ceramic content (again, this depends on the specific maker’s pads) is able to handle higher braking temperatures with theoretically less brake fade and faster braking recovery time, and depending on the specific formulation, may provide reduced braking noise, since the ceramic content tends to dampen noise by generating a noise frequency that’s not discernible by the human ear.
Be aware that not all pads labeled as “ceramic” may actually feature ceramic content. That’s one more reason to always stick with reputable and established brands, and to steer clear of pads of questionable origin.
Ceramic pads, generally speaking, tend to generate less noticeable “brake dust,” due to the lighter color of the friction material compounds. All brake pads will generate dust as they wear, but overall, ceramic pad dust is less noticeable. Many of today’s pads feature a “ceramic-metallic” structure.