Effective Stress Relief Without Jeopardizing Reliability in Overmolded Packages with Stress Buffers

It is well known that packaging can induce stresses in devices (IC's), dependent on package or device technology, design and materials, due to piezoelectric effects. There are various approaches to resolve this through design optimization at device or package level or material choice. One of the ways to achieve stress relief is by using stress buffers as part of the package. This can consist of low modulus materials like silicone-based gels. However, the use of such materials poses challenges towards achieving effective stress relief while at the same time maintaining robust reliability performance. This is due to the chemical and physical nature of silicone gels and their interactions in packaged devices. This paper describes some of these challenges and how they can be overcome.