はんだリフロー工程で発生するICのパッケージクラックに関する研究 : 第2報,応力特異場理論による樹脂の強度評価

抄録

The plastic packages of ICs have been changing from insertion types to surface mounted types. Reflow soldering is used for surface mounted ICs onto printed circuit boards. During this process, packages are heated to above 200°C. If the encapsulant absorbs moisture, package cracking may occur during the reflow soldering. It is known that the cracks are caused by vapor pressure generated inside the packages, causing excessive stress in the plastic. In the former report, moisture diffusion analysis in the plastic was performed and vapor pressure could be obtained. Since the edge tip of the chip pad where package cracking occurs is a singular point within the elastic stress field, strength evaluation for package cracking is not established. In this study, the quantitative strength evaluation of the plastic is investigated by using the stress singularity theory.