Improvement of leadframe positioning in molding process of integrated circuit packaging using superelastic Ni-Ti alloys

摘要

Application of superelastic Ni-Ti alloys on the locating-pins of a loading-frame that is used in molding process of integrated circuit packaging for leadframe positioning was studied. It is very easy for the locating pins of the fingers in a regular loading-frame to deform during the process, and consequently the alignment of the leadframe/chip/wire assemblies mis-aligned and the amount of inferior parts increases. In the experiment, superelastic Ni-Ti alloy pins were employed to replace the medium carbon steel ones. Resistivity measurement, tensile test, heat treatment, welding experiment and bending test were carried out to evaluate the design and the improvement. Bending and in-plant testing results show that superelastic Ni-Ti alloys improve the performance of the loading-frame greatly. The Ni-Ti locating pins can stand more than 350% of the tolerance of the displacement without producing unsatisfactory results.