Design and Fabrication of MEMS Test Socket for BGA IC Packages

We developed a novel ball grid array (BGA) test socket for an integrated circuit (IC) package test. The fabricated test socket has a cantilever array structure based on a silicon-on-insulator (SOI) wafer. We used micro-electromechanical systems (MEMS) technology to fabricate the test socket, which has a simple structure, an easy fabrication process, low contact force, rapid prototyping and low cost. We optimized the length, width and thickness of the cantilever for application to a BGA IC package test. We verified the deflection under applied force, contact resistance and characteristics of the signal path resistance. The contact force was 1.3 gram force per each cantilever beam which was 425 mu m long, 150 mu m wide and 10 mu m thick, with a deflection of 100 mu m. The contact resistance ranged from 0.7 to 0.75 ohm and the signal path resistance had a maximum value of 18 ohm. The test socket could be applied to actual BGA package tests.