Brake pads are made of friction material bonded to a steel backing plate. The friction material itself is a composite, a carefully engineered mix of fibers, metals, fillers, and binding agents designed to convert your car’s motion into heat through friction. What goes into that mix depends on the type of brake pad: organic, semi-metallic, or ceramic.
The Three Main Types of Friction Material
Every brake pad on the market falls into one of three categories, each built from a different base recipe. Organic pads (also called non-asbestos organic, or NAO) use fibers like glass, rubber, carbon, and Kevlar bound together with resin. They’re the quietest option and the softest on rotors, which is why they come standard on many passenger cars. The tradeoff is faster wear and weaker performance under heavy braking.
Semi-metallic pads are between 30% and 70% metal by weight. That metal content includes copper, iron, steel, and other composite alloys, mixed with graphite lubricant and additional fillers. The high metal content makes them excellent at pulling heat away from the rotor, which is why they’re favored for trucks, SUVs, and performance driving. They’re louder than organic pads and harder on rotors, but they last longer and handle high temperatures without losing stopping power.
Ceramic pads use dense ceramic fibers and clay compounds as their base, combined with small amounts of copper fiber and bonding agents. They produce less dust than semi-metallic pads, run quieter, and wear very consistently across a wide temperature range. They cost more and don’t dissipate heat quite as well as semi-metallic pads, which is why heavy-duty and high-performance vehicles often stick with metal-based formulas.
What Holds It All Together
Regardless of type, every brake pad needs a binder to hold its ingredients in a solid block. That binder is almost always phenolic resin, a synthetic polymer chosen for its high hardness, strong resistance to corrosion, and ability to wet and bond with a wide variety of filler materials. Phenolic resin is also cheap and easy to mold, which has made it the default choice in brake pad manufacturing for decades.
Standard phenolic resin begins to break down thermally between about 280°C and 350°C (roughly 535°F to 660°F). That’s adequate for everyday driving, but modern vehicles with higher speeds and heavier loads can push past those limits. Manufacturers now use modified versions of phenolic resin that resist decomposition at significantly higher temperatures, some holding up past 480°C (about 900°F). When resin breaks down, the pad loses friction and you experience what’s commonly called brake fade.
The Steel Backing Plate
Behind the friction material sits a steel backing plate, the rigid foundation that transfers force from the brake caliper evenly across the pad. Most backing plates are stamped from steel sheet, though some heavy-duty applications use cast iron. The friction material attaches to this plate in one of three ways: adhesive bonding, rivets, or mechanical retention systems.
Adhesive bonding is straightforward but can degrade over time with heat cycling. Stamped-hole backing plates have punched openings that allow friction material to flow through and lock in place during manufacturing. Wire mesh plates weld a layer of steel mesh to the plate surface for the same purpose. A newer approach, developed by Canadian manufacturer NUCAP, uses small hooks pressed into the plate surface that embed directly into the friction block as it’s molded. This eliminates the need for through-holes and creates a strong mechanical bond between the friction material and the plate.
Noise-Damping Layers
Many brake pads include a thin composite layer called a shim, bonded to the back of the steel plate. Shims are built from alternating layers of steel and rubber or other elastic polymers. When the pad vibrates during braking, the soft polymer layer between the steel sheets deforms and absorbs energy, reducing the high-pitched squeal that would otherwise reach the cabin. These multi-layer shims are one of the most common engineering solutions for brake noise, and their design has a measurable impact on how quiet a braking system feels.
Why Copper Is Disappearing From Brake Pads
Copper has been a key ingredient in brake pads for years, valued for its ability to conduct heat and smooth out friction. But copper dust washes off roads and into waterways, where it’s toxic to aquatic life. California passed a law restricting heavy metals and asbestos in brake pads starting in 2014, with copper limited to a maximum of 5% by weight in 2021. As of 2025, the law reduces allowable copper to nearly zero, defined as no more than 0.5% by weight. Washington State passed similar legislation in 2010.
The Society of Automotive Engineers developed a standardized marking system so consumers can identify compliant pads. Pads marked with an “N” contain no more than 0.5% copper and meet all current environmental requirements. This shift has pushed manufacturers to reformulate their compounds, replacing copper with alternatives like tin, bismuth, and various mineral fibers that can fill a similar thermal and friction role without the environmental damage.
Why Asbestos Was Removed
For most of the 20th century, asbestos was the go-to friction material in brake pads. It was heat-resistant, cheap, and durable. It was also a Group 1 carcinogen, classified by the International Agency for Research on Cancer as definitively causing cancer in humans. Mechanics who serviced brakes were especially at risk, inhaling fine asbestos fibers released as pads wore down. Most developed countries phased asbestos out of brake manufacturing through the late 1990s and 2000s, and it’s now banned in virtually all automotive friction products worldwide. The entire “non-asbestos organic” category exists because the industry needed a name for the replacement formulas that followed.
How Material Choice Affects Daily Driving
The composition of your brake pads determines four things you’ll actually notice: noise, dust, pedal feel, and how long they last. Organic pads are the quietest and produce soft, easy-to-modulate pedal feel, but they wear fastest and can fade during aggressive driving. Semi-metallic pads last longest and handle heat best, but they generate more noise and produce coarse, dark brake dust that clings to wheels. Ceramic pads strike a middle ground with low dust, quiet operation, and consistent performance, though they cost 20% to 50% more than the other types.
For most commuter cars driven in typical conditions, organic or ceramic pads are a natural fit. If you tow, drive in mountains, or push your car hard, semi-metallic pads give you more thermal headroom. The “best” material is the one matched to how you actually use your vehicle, not the most expensive option on the shelf.