New probe microstructure for full-wafer, contact-probe cards

We have developed a microstructure probe that features a pyramidal contact point and a cantilever structure. This probe is suitable for wafer-level burn-in (WLBI) testing, function testing, and circuit-board O/S testing. It has a simple beam lead (only 400-600 /spl mu/m long and 50-100 /spl mu/m wide) and can withstand over one million probings. The per-probe contact force is approximately 0.3 g, making the probe suitable for WLBI testing, which requires low contact force. The simple structure and small dimensions of this probe give it excellent high-frequency characteristics. Function testing of a probe card mated to SDRAM was successfully done at 100 MHz. A wafer-scale probe card can be made by splitting the card into several parts and tiling them on a base substrate. This tiling increases the yield and facilitates repairs. It also makes it possible to fabricate larger cards. This structure gives the probe substrate a relatively large (up to 10 ppm//spl deg/C) coefficient of thermal expansion, which is similar to that for alumina.