Mitsumasa Kojima

Photosensitive polyimide for IC devices

Photosensitive polyimide has potential applications for interlayer insulation, alpha-ray shielding, and buffer coating of IC and LSI devices because it offers reduction in processing time. There are two main methods used to photosensitize polyimide. One is based on ion bonding and the other on covalent bonding between polyamic acid and photosensitive groups. The sensitivity, resolution, and mechanical properties such as tensile strength, elongation, and adhesion strength of the photosensitive polyimides have been investigated. The studies indicate that the covalent-bonding type is better than the ion-bonding type in terms of optical properties; the physical properties of the ion-bonding type, however, are much better. In terms of the physical properties conventional nonphotosensitive polyimides still have superior properties compared to photosensitive polyimides.<<ETX>>

New polyimide for multi-chip module application

P-terphenyltetracarboxylic dianhydride (p-TPDA), which has a rodlike structure, has been developed as a raw material for polyimides in order to reduce the propagation delay time associated with polyimide packaging for multichip modules. The coefficient of thermal expansion (CTE) of the polyimides derived from p-TPDA is approximately 2*10/sup -6/. This is much lower than that of conventional polyimides derived from bisphenyltetracarboxylic dianhydride (BPDA), which have a CTE of 8*10/sup -6/ K/sup -1/. Another attribute that these polyimides have is low dielectric constant, with a typical value of about 2.9. As a result, this polyimide can give improved performance when used in multichip module applications.<<ETX>>