EXPANDABLE BASE FILM, DICING FILM, SURFACE PROTECTIVE FILM FOR SEMICONDUCTOR, AND METHOD OF MANUFACTURING SEMICONDUCTOR DEVICE

摘要

PROBLEM TO BE SOLVED: To provide an expandable base film which is excellent in stress relaxation properties and is reduced in anisotropy of tensile elongation at break and anisotropy of tear strength.SOLUTION: The expandable base film contains: a polymer A containing 70-95 mol% of a constituent unit (X) derived from 4-methyl-1-pentene and 5-30 mol% of a constituent unit (Y) derived from a C2-C20α-olefin other than 4-methyl-1-pentene; and a polymer B containing the constituent unit (Y) as a main component. When the total amount of the polymer A and the polymer B is 100 pts.mass, the content of the polymer A is 20-90 pts.mass and the content of the polymer B is 10-80 pts.mass.