Expandable film, a manufacturing method of the dicing film, and a semiconductor device

A low pollution, the conventional olefinic expandable substrate was insufficient, have high expandability, it is an object necking hard olefinic expandable substrate and to obtain a dicing film. To achieve the above object, comprises a tensile modulus at 23 ° C. is a 100～500MPa 1-butene · alpha-olefin copolymer polymer (A), the propylene · alpha-olefin copolymer (b1), 23 ° C. tensile propylene elastomer composition modulus of 10~50MPa and (B), a substrate comprising a in the content of the (B) is a total of 100 parts by weight of (a) and (B) in contrast, 30 to 70 parts by weight, the expandable film. .The