A Highly Manufacturable Large Area Array MEMS Probe Card Using Electroplating and Flipchip Bonding

A highly manufacturable microelectromechanical systems (MEMS) probe card was developed by using flipchip bonding technology, which is applicable to large area array bonding ranging from 2- to 8-in substrates. A cantilever-type probe structure for an actual device was electroplated with nickel-cobalt and was bonded with nickel bump, which anchored on the ceramic substrate. Gold-tin (AuSn) was used as the material of flipchip bonding between the cantilever beam and bump. Flipchip bonding itself is not a new technology, but combining it with a MEMS probe card is a novel technique in large area bonding because of the high reflow temperature (280degC, Au₈₀Sn₂₀). Various parallelism bonding processes were used to find the best bonding method. The MEMS probe card was designed to achieve a deflection of 50 mum when 2 gram force (gf) was applied and to keep elasticity up to a deflection of 150 mum. The specification of the probe card was for actual 12-in dynamic random access memory testing. The measured average contact force was 2.04 gf at a 50-mum overdrive. In addition, mechanical and electrical characteristics were also suitable for the actual device test.