MULTILAYER POLYMIDE FILM AND FLEXIBLE METAL LAMINATED BOARD
Provided are a multilayer polyimide film that hardly suffers from the peeling of the layers from each other or the clouding of a space between the layers (turning white in color) during heating at a high temperature and a flexible metal-clad laminate using such a multilayer polyimide film. This object can be attained by a multilayer polyimide film having a thermoplastic polyimide layer on at least one side of a nonthermoplastic polyimide layer, wherein at least 60% of the total number of moles of an acid dianhydride monomer and a diamine monomer that constitute the thermoplastic polyimide is the same type of monomer as at least one type of acid dianhydride monomer and at least one type of diamine monomer that constitute the nonthermoplastic polyimide.
1 . A multilayer polyimide film having a thermoplastic polyimide layer on at least one side of a nonthermoplastic polyimide layer, wherein at least 60% of the total number of moles of an acid dianhydride monomer and a diamine monomer that constitute the thermoplastic polyimide is the same type of monomer as at least one type of acid dianhydride monomer and at least one type of diamine monomer that constitute the nonthermoplastic polyimide.
2 . The multilayer polyimide film as set forth in claim 1 , wherein at least 80% of the total number of moles of the acid dianhydride monomer and the diamine monomer that constitute the thermoplastic polyimide is the same type of monomer as said at least one type of acid dianhydride monomer and said at least one type of diamine monomer that constitute the nonthermoplastic polyimide.
3 . The multilayer polyimide film as set forth in claim 1 , wherein the acid dianhydride monomer that constitutes the thermoplastic polyimide is at least one type of acid dianhydride selected from the group consisting of pyromellitic acid dianhydride, 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride, and 3,3′,4,4′-benzophenonetetracarboxylic acid dianhydride.
4 . The multilayer polyimide film as set forth in claim 1 , wherein the diamine monomer that constitutes the thermoplastic polyimide is 4,4′-diaminodiphenylether or 2,2-bis[4-(4-aminophenoxy)phenyl]propane.
5 . The multilayer polyimide film as set forth in claim 1 , wherein the acid dianhydride monomer that constitutes the thermoplastic polyimide is a combination of pyromellitic acid dianhydride and 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride, and the diamine monomer that constitutes the thermoplastic polyimide is 2,2-bis[4-(4-aminophenoxy)phenyl]propane.
6 . The multilayer polyimide film as set forth in claim 5 , wherein the ratio between pyromellitic acid dianhydride and 3,3′,4,4′-biphenyltetracarboxylic acid dianhydride, which are acid dianhydride monomers that constitute the thermoplastic polyimide, is 70/30 to 95/5.
7 . The multilayer polyimide film as set forth in claim 1 , wherein the acid dianhydride monomer that constitutes the thermoplastic polyimide is pyromellitic acid dianhydride, and the diamine monomer that constitutes the thermoplastic polyimide is 2,2-bis[4-(4-aminophenoxy)phenyl]propane.
8 . The multilayer polyimide film as set forth in claim 1 , said multilayer polyimide film being produced by multilayer coextrusion.
9 . A flexible metal-clad laminate obtained by bonding a sheet of metal foil to a multilayer polyimide film as set forth in claim 1 .
10 . The multilayer polyimide film as set forth in claim 5 , said multilayer polyimide film being produced by multilayer coextrusion.
11 . The multilayer polyimide film as set forth in claim 6 , said multilayer polyimide film being produced by multilayer coextrusion.
12 . The multilayer polyimide film as set forth in claim 7 , said multilayer polyimide film being produced by multilayer coextrusion.
13 . A flexible metal-clad laminate obtained by bonding a sheet of metal foil to a multilayer polyimide film as set forth in claim 5 .
14 . A flexible metal-clad laminate obtained by bonding a sheet of metal foil to a multilayer polyimide film as set forth in claim 6 .
15 . A flexible metal-clad laminate obtained by bonding a sheet of metal foil to a multilayer polyimide film as set forth in claim 7 .
16 . A flexible metal-clad laminate obtained by bonding a sheet of metal foil to a multilayer polyimide film as set forth in claim 10 .
17 . A flexible metal-clad laminate obtained by bonding a sheet of metal foil to a multilayer polyimide film as set forth in claim 11 .
18 . A flexible metal-clad laminate obtained by bonding a sheet of metal foil to a multilayer polyimide film as set forth in claim 12 .