Evaluation of wire bond integrity through force detected wire vibration analysis

This paper studies the feasibility of using force measurement to detect wire vibration for the evaluation of wire bond integrity. In this system, a tapping probe sends a single pulse or multiple pulses of controlled motion to the substrate adjacent to a bond end. This mechanical shock induces vibration propagation to the wire along and through the neighbouring materials. Another probe of a micro force sensor is put in touch with the wire to pick up the wire vibration, which in turn, correlates to the bonding status of the joined materials. By interpreting the vibration signals in time, frequency, and phase domains, bond integrity, including fully bonded, partially bonded, and touching yet not-bonded, has been determined. The results show that the proposed approach is promising for finer and denser wire bond evaluation non-destructively, accurately, and at low cost.