RELEASE FILM FOR SEMICONDUCTOR RESIN MOLDS
To provide a release film which has an extremely low gas permeability, an enormously small mold contamination by a mold resin and a high releasability. A gas barrier release film for semiconductor resin molds, comprising a release layer (I) having excellent releasability, a plastic support layer (II) supporting the release layer, and a gas restraint layer (III) made of a metal or a metal oxide, formed between the release layer and the support layer, and having a xylene gas permeability of at most 10 −15 (kmol m/(s·m 2 ·kPa)) at 170° C. The release layer (I) is preferably formed from a fluororesin such as an ethylene/tetrafluoroethylene copolymer, and a metal oxide layer is preferably a layer of an oxide such as an aluminum oxide, a silicon oxide or a magnesium oxide.
1 . A gas barrier release film for semiconductor resin molds, comprising a release layer (I) having excellent releasability, a plastic support layer (II) supporting the release layer, and a gas restraint layer (III) made of a metal or a metal oxide, formed between the release layer and the support layer, and having a xylene gas permeability of at most 10 −15 (kmol m/(s·m 2 ·kPa)) at 170° C.
2 . The release film according to claim 1 wherein the above release layer (I) is formed from a fluororesin.
3 . The release film according to claim 2 wherein the above fluororesin is an ethylene/tetrafluoroethylene copolymer.
4 . The release film according to claim 1 , wherein the plastic support layer (II) has a stress at a 200% elongation of from 1 MPa to 100 MPa at 170° C.
5 . The release film according to claim 1 , wherein the plastic support layer (II) is formed from an ethylene/vinyl alcohol copolymer.
6 . The release film according to claim 1 , wherein the gas restraint layer (III) is formed on the plastic support layer (II).
7 . The release film according to claim 1 , wherein the gas restraint layer (III) is a layer of at least one oxide selected from a group consisting of aluminum oxide, silicon oxide and magnesium oxide.
8 . The release film according to claim 1 , wherein the gas restraint layer (III) is a layer of at least one metal selected from a group consisting of aluminum, tin, chrome or stainless steel.
9 . The release film according to claim 1 , wherein a resin protection layer (III′) is formed on the gas restraint layer (III).
10 . The release film according to claim 1 , wherein at least one surface of the release film is satin-finished.