抄録
It is well known that a warpage phenomenon of LSI package is influenced by thermal and chemical shrinkage, in the meantime; there are few reports which study a chemical shrinkage for the stress analysis. In this report, a chemical shrinkage was defined as a function of temperature same as a coefficient of thermal expansion, then a thermal viscoelastic warpage analysis was carried out for a BGA package in various temperature range. It was found that the calculated values had a good correspondence with the measured ones in terms of package warpage from 25℃ to 260℃. Thus, the warpage mechanism became clear through the parameter analysis of material properties. In order to obtain a minimum warpage for a material designing of mold compound, the following suggestion is supported; 1) To increase Tg and to decrease CTE & 2) To reduce modulus at high temperature.
