A Novel Micromachined Claw Probe for the Electrical Testing of Microsolder Ball

Abstract

This paper presents a micromachined claw probe with electroplating nickel for microsolder ball electrical testing applications. The suspension claw structure consists of two bridges and four curved cantilevers, which have a flexible spring constant in a small region. The out-of-plane claw-probe unit was fabricated using silicon bulk micromachining, titanium deposition, and nickel electroplating processes. The typical bending cantilever structure, made by nickel electroplating, had a thickness of 6.5 μm, a width of 10 μm, and a length of 80 μm. The maximum out-of-plane deflections of the fabricated 40 × 40 claw-probe array were approximately 50 ± 1.2 μm, under the effect of residual tensile stress of 923 MPa. For the probing test of the microsolder ball with a diameter of 200 μm, under the contact force of 1.75 mN, the measured path resistance was about 30 Ω, and the moving stroke of the microsolder ball was 14 μm. The extendable overdrive stroke was over 30 μm, after probe contact with the microsolder ball, and obvious damage was not observed on the surfaces of the claw probe except for several slight scrapes on the sidewall of the microsolder ball. This probe card is potentially capable of providing a very large number of micromachined probes in an array format and can also satisfy the requirements for a fine-pitch ball grid array and low-cost wafer-level testing.[ 2011-0299]Index Terms-Claw probe, electroplated nickel, microsolder ball, residual stresses.