Laminate for electronic circuit

Abstract

The present invention is directed to a laminate having a layer construction of metal-insulating layer-metal or a layer construction of metal-insulating layer, which laminate meets conditions for developing large adhesive strength between the insulating layer and the metal, as well as to an insulating film and an electronic circuit using the laminate. The laminate has a layer construction of first metal layer/insulating layer/second metal layer or a layer construction of metal layer/insulating layer. The insulating layer 1 has a multilayer structure of two or more layers. The layers on the side of the adhesive interface with each metal layer (a copper foil 3 and an SUS foil 4 ), out of the layers constituting the insulating layer 1 , each are a thermoplastic resin layer 2 . The minimum value of the storage modulus at a temperature at or above Tg of the thermoplastic resin layer 2 is not more than 10 6 Pa.

What is claimed is:  
     
         1 . A laminate comprising a combination of a metal layer with an insulating layer, said laminate having a layer construction of first metal layer/insulating layer/second metal layer or a layer construction of metal layer/insulating layer, wherein 
 said insulating layer has a multilayer structure of two or more layers,    the layer on the side of the adhesive interface with the metal layer, out of the layers constituting the insulating layer, is a thermoplastic resin layer, and    the minimum value of the storage modulus at a temperature at or above Tg of the thermoplastic resin layer is not more than 10 6  Pa.    
     
     
         2 . The laminate according to  claim 1 , wherein at least one layer constituting the insulating layer is formed of a polyimide resin or is a polyimide film.  
     
     
         3 . The laminate according to  claim 1 , wherein all the layers constituting the insulating layer each are formed of a polyimide resin or are a polyimide film.  
     
     
         4 . The laminate according to  claim 1 , wherein the metal layers each are formed of a material selected from the group consisting of copper alloy, copper, and stainless steel and the material constituting the first metal layer is the same as or different from the material constituting the second metal layer.  
     
     
         5 . An electronic circuit produced by using the laminate according to any one of  claims 1  to  4 .  
     
     
         6 . An insulating film comprising: a resin film or a resin layer as an insulating layer; and, provided on both sides or one side of the insulating layer, a thermoplastic resin layer having a minimum value of the storage modulus of not more than 10 6  Pa at a temperature at or above Tg of the thermoplastic resin layer.  
     
     
         7 . The insulating film according to  claim 6 , wherein at least one layer constituting the insulating layer is a polyimide film or is formed of a polyimide resin.  
     
     
         8 . The insulating film according to  claim 6 , wherein all the layers constituting the insulating layer each are a polyimide film or are formed of a polyimide resin.  
     
     
         9 . A laminate comprising a metal and an insulating film, said laminate being produced by using the insulating film according to  claim 6 .  
     
     
         10 . An electronic circuit produced by using the laminate according to  claim 9 .  
     
     
         11 . A process for producing a laminate, comprising the step of thermocompression bonding a core insulating layer, a thermoplastic resin layer, which is disposed on both sides or one side (z-plane) of the core insulating layer, has an adhesive property and has a minimum value of the storage modulus of not more than 10 6  Pa at a temperature at or above Tg of the thermoplastic resin layer, and a metal layer disposed on the surface of the thermoplastic resin layer to one another at a temperature of Tg or above.  
     
     
         12 . The process for producing the laminate according to  claim 11 , wherein the thermocompression bonding is carried out under temperature conditions such that the storage modulus of the thermoplastic resin is minimum.