Yun-Hsin Liao

New ball grid array module test sockets

New sockets have been-designed and fabricated for testing advanced BGA modules. The socket can easily be custom designed to match any BGA footprint, size and pitch. The socket materials, including the contact metallurgy, frame and the elastomeric materials, are capable of performing burn-in test at temperatures higher than 150/spl deg/C for a prolonged time in air. The compliance of the sockets are tailored to bring just enough contact force to penetrate the thin oxide layer on the solder without severely deforming the solder ball. As a result, low and stable contact resistance has been achieved with low contact force in repeated touch-down cycles. The contact force to solder balls ranges from 12 to 50 grams per contact at 10 mils displacement. The contact structure and geometry have been enhanced to allow for multiple module test cycles (>50000 life cycles) with negligible damage to the contact pads.