I. INTRODUCTION
In present, the manufacturing technology and equipment
development in semiconductor fields are very advanced due to the
market competition. However, the investment of the package
technology, in contrast, is less that that of the previous. Therefore, in
the package technology, some issues are still observed, such as the
adhesion force of wire between chip and lead-frame in the integrated
circuit (IC), the choice of lead-frame material and the contamination
in mixing molding compound. All of these deteriorated factors are
able to degrade the electrical characteristics and operational
performance of ICs.
The life operation of IC products can be divided by three stages,
which are infant period, useful-life period, and wear-out period,
respectively. The failure distribution of these periods can be
described as a bathtub curve [1-3], shown in Fig. 1. Basically, the
failure rate is very high in infant period, because some existing innerdefects
are enhanced dramatically. Normally, the failure ICs are able
to be screened out in this infant period in infant mortality (IM) [4-6]
experiment. The conditions of IM experiment contain high
temperature operating at 125