Application of Photosensitive Polyimide to Multichip Module(MCM-D).

Abstract

In the photosensitive polyimide(PI) application to the multichip module, MCM-D, two kinds of commercially available photosensitive PI, UR-3140 which has an ionic bond crosslinker and TL-530A which has an ester bond crosslinker, have been characterized.The imidization temperature depends on the solvent release temperature and decomposition temperature of the incorporated crosslinkers. The ester bond PI requires a higher thermal treatment temperature than that of the ionic bond PI. Although the temperature of 100% imide conversion for each PI is below 300°C, in order to complete the outgassing and to obtain the desired mechanical properties, higher thermal treatment temperature and holding time, 400°C for ionic bond PI and 450°C for the ester bond PI, is needed. Furthermore, high temperature cure also drastically influence on their mechanical properties. Concerning the adhesion, the hydrophobic thin layer formed by argon (Ar) ion bombardment can protect the PI-metal interface from the invasion of water. The degree of roughness of PI surface formed by Ar ion bombardment and the chemical bonding between PI-metal seem to have no effect in improving the adhesion strength after pressure cooker test (121°C, 100% RH, 2.1atm for 100h).