Expandable film, dicing film, and semiconductor device manufacturing method

An object of the present invention is to obtain an olefinic expandable substrate and a dicing film that are low in contamination and have high expandability and are difficult to neck, which is insufficient with conventional olefinic expandable substrates. In order to achieve the above-mentioned object, a 1-butene / α-olefin copolymer (A) having a tensile elastic modulus at 23 ° C. of 100 to 500 MPa and a propylene / α-olefin copolymer (b1) are contained at 23 ° C. And a propylene-based elastomer composition (B) having a tensile modulus of elasticity of 10 to 50 MPa, wherein the content of (B) is 100 parts by weight in total of (A) and (B). On the other hand, the expandable film is 30 to 70 parts by weight. [Selection] Figure 2