Electrical characterization of BGA test socket for high-speed applications

This paper discusses the electrical characterization of a high-density and high-speed BGA (ball grid array) socket. The socket is built from copper-clad pogo pins and pinned in a 32/spl times/32 mm array with 400 pins on a 1.27 mm pitch. It provides power/ground array, and signal pins designed to offer 348 signal lines. The socket-base dielectric has a dielectric constant of about 4.2. The BGA test socket discussed in the paper is being targeted for high-speed testing fixture applications and their pins are closely spaced. Extensive TDR (time domain reflectometry) measurements and IPA510 simulations have been used to extract their significant electrical properties such as differential skews, characteristic impedances, reflection characteristics, and crosstalk. The bandwidth of the BGA socket from the 3 dB return loss criteria was calculated to be around 5 GHz for time domain measurements.