Design and fabrication of a highly manufacturable MEMS probe card for high speed testing

We have designed and fabricated a micro-electro mechanical system (MEMS) probe card, which is suitable for a manufactured product, to achieve a deflection of 50 mum at a force of 1.5 gram (g) and a probe structure height of 720 mum. The cantilever structure consists of a tip and beam of Ni-Co, a bump of Ni and AuSn solder between them. In order to make the probe card compliant, all moving structures such as the tip, beam and bumps were electroplated with nickel, nickel-cobalt and gold solutions. The fabricated MEMS probe card can endure more than 150 mum overdrive and prevent tip damage from particles owing mainly to its high bump height and enhanced high frequency test, putting capacitors between the driving voltage and ground. Based on our experimental results, the average contact force was approximately 1.41 gram force (gf) at 50 mum of deflection and the total path resistance was less than 5 Omega for all pins, while the leakage current was less than 5 nA.