Figure 1 outlines the critical steps in the failure-analysis process. Initial failure observations are usually optical. For some probe card failures, although obvious visually, you may need high-magnification electron microscopy to determine the root cause. The analysis method can be either destructive or nondestructive, depending on the nature of the failure. Failure Mechanisms Probes, themselves, are the most common causes of probe-card failure because they may be subject to overstress, and this article will focus on probe failure analysis.
Probes are susceptible to damage from a number of sources.
Bending operations during manufacturing can introduce microcracks in the bend area that can propagate during touchdown cycles and cause a probe to fracture. Abnormal wear of only a few probes in a probe card may point to a faulty card design. If exposed to chemicals or excessive humidity, probes can corrode. The first step in a failure investigation is to observe the probe-card failure. Such a system typically requires very little sample preparation, and it generates data quickly.