Effects of ACFs Modulus and Adhesion Strength on the Bending Reliability of CIF(Chip-in-Flex) Packages at Humid Environment

Abstract

Two methods are proposed to improve the bending reliability of the CIF package at room temperature as well as at heated and humid conditions. The first is the increase of resin modulus of ACFs, and the second is the increase of adhesion strength of ACFs. For experiments, 2 types of ACFs with similar adhesion strength and 2 types of ACFs with similar resin modulus were prepared. Dynamic bending tests of ACFs-boned CIF packages were performed at bending radius of 6 mm and room temperature. Moreover, the environmental reliability of CIF packages were also evaluated at the 85 degrees C/85% RH thermal humidity storage test for 1,000 hours using a bending rod of 6 mm radius. As a result, it was found out that the most effective method to obtain higher bending reliability of CIF packages is increasing the modulus of ACFs not only at room temperature but also at thermal and humid conditions.