Investigating wire bonding pull testing and its calculation basics
This study found that standard wire pull testing models introduced more than 20 years ago are insufficient under certain circumstances, including the larger wire bond angles used in applications for automotive control units, pressure sensor devices and COB. The techniques assessed were those given in the German industrial specification DVS Merkblatt 2811 and the international standards MIL-STD-883G and ASTM-F459-06 by comparing the calculated results with actual wire bond pull tests results. The detrimental impact of such failures on standard wire bonding quality control parameters (e.g. the typically used cpk value) can be significant. A new FEM model was developed to investigate possible solutions to the shortfall in accuracy. The data thus obtained was then fed into a new analytical model, based on the Capstan model, which is easily transferred to standard industry and research settings. All measurements, calculations and simulation results were correlated.