RF electrical measurements of fine pitch BGA packages

A series of fine pitched ball grid arrays (BGAs) were measured on an Network Analyzer using a novel technique to de-embed the package test fixture and provide an accurate representation of the electrical characteristics of the package. The technique consisted of the design and fabrication of a RF circuit board. Duplicates of the board were modified to become a series of calibration fixtures while others, with sample packages attached, were modified to become test fixtures. The packages, attached to circuit boards, were measured to determine their performance at the RF frequencies of most cellular phone applications. Measurements included the return losses looking into several leads of the package that were 50 Ω terminated and insertion losses from one terminated lead to an adjacent one. These measurements can be used for verifying models or for characterizing packages