Effects of die‐pad resonance on ultrasonic bond quality of wire bonds

Abstract

Purpose

Wire bonding is an important method of interconnection in microelectronics. Ultrasonic energy is known to soften metallic materials and hence when used in the wire bond process it is effective to decrease the flow stress similar to thermal energy. The paper aims to address this issue.

Design/methodology/approach

Detailed resonance studies show that some designs have closeby resonance compared to the bonding frequency which causes enhanced vibration resulting in such over squashed bonds. Hence, precautions in the design stage are necessary to understand the closeby resonance frequencies and corresponding mode shapes of the leadframe that are in‐plane in nature along the transducer axis that can be excited by the capillary's motion. This can be determined a priori using numerical methods such as finite element method. In this paper, one such case study has been dealt in detail to explain the overall methodology.

Findings

To minimize the effects of resonance, damping should be increased by bonding polyimide tapes to enhance damping and stiffness which results in better ball bonds with optimum bell shape.

Originality/value

The paper explains the methodology of wire bonding in microelectronics.

Citation

Srikanth, N. (2007), "Effects of die‐pad resonance on ultrasonic bond quality of wire bonds", Microelectronics International, Vol. 24 No. 1, pp. 23-26. https://doi.org/10.1108/13565360710725900