FILM FOR SUPPORTING SEMICONDUCTOR CHIP

摘要

PROBLEM TO BE SOLVED: To prevent a necking in an expanding process by making a film mainly of a mixture made of specific material and by establishing a certain relationship between a stress of an s-s curve to a tensile strain in the longitudinal direction and a stress of an s-s curve to a tensile strain in the lateral direction and by making the tangential coefficients of both the s-s curves in all the ranges. SOLUTION: The main constituent of a film 1 is a mixture ofα-olefin polymer of polyethylene, polypropylene, or polybutene andα-olefin copolymer having 2 to 8 carbon atoms. There is a relationship ofσr =(0.8 to 1.2)σc , whereσr is a stress of an S-S curve to the maximum tensile strain in all radial directions when the film 1 is expanded with respect to tension in the longitudinal direction of the film 1 andσc is a stress of an S-S curve to the maximum tensile strain in all radial directions when the film 1 is expanded with respect to tension in the lateral direction of the film 1. Also, the tangential coefficients of both the S-S curves are made positive in all ranges.