Investigation of Contact Behavior and Design of Vertical Probe for Wafer Level Probing

It is necessary to analyze the mechanism of bump wafer probing, for bump height variation and probe mark area significantly influence flip chip assembly reliability. This causes the development of an effective and reliable testing method which becomes more important as the testing method has to satisfy the requirements of fine pitch and area array bumps. Certainly the vertical probe card is a reliable solution to satisfy these requirements of bump wafer probing. In this paper, the mechanism of bump wafer probing is investigated and the relationships among tip-sphere contact force, overdrive, probe geometries, material properties, and scrub mark area are derived. This paper further investigates bump wafer probing criteria which compares the results of several contact models with the experimental results to avoid bump damage. In addition, a simple and accurate theoretical analysis is established for rapidly designing an appropriate probing system for bump wafer probing. Finally, the effects of vertical probes with various geometries on bump wafer probing are investigated.