Electronics test fixtures are used to test contact points on circuit boards during manual or automated testing. Products are used to test daughter cards, flex circuits, liquid crystal displays (LCDs), loop-back boards, multi-chip modules, optical packages, printed circuit boards (PCBs), radio frequency (RF) modules, and hybrid boards. Electronic test fixtures are also used to test integrated circuits (ICs). Typically, automated test equipment (ATE) is attached to an interface between the IC and a device under test (DUT) board. As a rule, DUT boards are designed to meet the all of the mechanical and electrical requirements of both IC chips and electronic test fixtures. There are many types of electronics test fixtures. Examples include manufacturing defect analyzers, in-circuit testers, and functional analyzers. Manufacturing defect analyzers (MDAs) or analog circuit testers are used to identify and locate defects such as shorts and missing components. Because the unit under test (UUT) is powered-down, however, MDAs are not designed for testing digital ICs. In-circuit analyzers or digital circuit testers are used for testing components that are part of a board assembly. Because the UUT is powered-up or hot, the components under test are considered to be in a circuit. Functional analyzers or emulators are electronics test fixtures that simulate an operating environment. They are used for testing boards against their functional specifications. Electronics test fixtures for integrated circuits are designed for use with various package types. Examples include ball grid array (BGA), land grid array (LGA), and pin grid array (PGA); chip scale package (CSP); single in-line package (SIP) and dual in-line package (DIP); plastic leaded chip carrier (PLCC); small outline integrated circuit (SOIC); and transistor outline (TO). Package types for electronics test fixtures also include single in-line memory module (SIMM), dual in-line memory module (DIMM), and small outline dual in-line memory module (SO-DIMM). Semiconductor test fixtures may incorporate semiconductor test sockets that are designed for use with specific products. For example, some electronic test fixtures are designed for use with optical interface packages, implantable medical hybrids, RF modules over 10 GHz, packages with test pads on both top and bottom, or packages mounted on 35-mm flex circuits. Other electronic test fixtures include sockets with heat sinks, internal filter caps, or features for testing surface-mount technology (SMT) devices.