The term "compact heat exchangers" refers to a general class of heat exchanger types. These heat exchangers are "laid up" using multiple layers of corrugated (or serpentine) plate fins and separating plates or tubes. The assembled heat exchanger is held in a fixture and brazed in one of several types of braze furnaces. The most common fabrication material is aluminum. However, it may be made of copper-brass, stainless steel, titanium, superalloys, or even carbon-fiber composites. The most common type is made of aluminum and was originally developed in the mid-1940s.

Compact heat exchangers made of aluminum are commonly referred to as "brazed aluminum heat exchangers". Early brazed aluminum designs were made as small aircraft oil coolers. In the 1950s, brazed aluminum was applied to large designs used for gas separation and were brazed by "salt bath" brazing. Brazed aluminum technology has rapidly expanded into many application fields, including aircraft/aerospace, automotive, gas separation/liquefaction, electronic equipment cooling, and residential air-conditioning.

The aluminum brazing technology has evolved to the currently used "controlled atmosphere flux brazing" (known as the CAB process and Nocolok if a noncorrosive potassium-fluoroaluminate flux is used) and vacuum brazing. The automotive is a high-volume user of brazed aluminum technology and nearly all automotive heat exchangers (e.g., radiators, oil coolers, condensers, and evaporators) are now brazed aluminum using the Nocolok brazing method, which is suitable for high-volume production. Brazed copper-brass technology is used in automotive radiators and charge-air coolers, and uses a "controlled atmosphere flux brazing process (known as "Cupro-braze"). Stainless steel, titanium, and superalloy materials are used for higher operating temperature and better corrosion resistance than can be supported by aluminum. Recent new technology involves carbon-fiber composite material technology and is applicable to high-temperature applications (e.g., above 800 °C). Manufacturing and brazing technology are addressed in Section Mechanical design.

Brazed plate-fin heat exchangers are used for gas-to-gas, gas-to-liquid, or two-phase service. As previously noted, they were initially developed for gas-to-gas and gas-to-liquid aircraft and mobile applications using aluminum materials. Here, compactness and low weight were valued. The stainless steel variety focused on regenerative heat exchangers for gas turbines, which also valued compactness. Because of high gas turbine exhaust temperatures, stainless steel was used for construction.

The brazed aluminum concept has found wide acceptance for gas processing applications (separation and liquefaction). This includes gas-to-gas and two-phase service. Such heat exchangers may be in cores as large as 1.5 × 1.5 cross section × 9 m length, and manifolded into large batteries of heat exchanger. The Brazed Aluminum Plate-Fin Heat Exchanger Manufacturers' Association (ALPEMA) publishes a design standard for the design of such heat exchangers used in gas processing. This standard also gives the membership list of association members. This standard is applicable to large industrial brazed aluminum designs. Small brazed aluminum designs are used for air-to-liquid or oil coolers, and as automotive refrigeration evaporators and condensers.