Design Optimization of Needle Geometry for Wafer-Level Probing Test

The probing test is a typical quality control method for individual chips on a wafer. With a proper design, the service life of probing needles in the probe card can be sufficiently elongated and hence reduces the testing cost. In this paper, we followed the Taguchi method with the L₁₈(2¹ times 3⁷) orthogonal array to obtain an optimal geometrical design of the probing needle based on the minimization of the scrub length the probe tip travels during a wafer-level probing test procedure. Geometrical factors of the needle included tip shape, needle diameter, beam length, taper length, knee diameter, shooting angle, tip length, and tip diameter. Importance of theses factors on the scrub length was also ranked.