Cof flexible printed wiring board and semiconductor device

Abstract

A COF flexible printed wiring board, used for a semiconductor device, contains an insulating layer, a wiring pattern formed of a conductor layer on one side of the insulating layer, on which a semiconductor chip is to be mounted, and a heat-resistant releasing layer, wherein the releasing layer is formed from a releasing agent and is provided on a surface of the insulating layer, which surface is opposite to the mounting side of the semiconductor chip, and the releasing layer and the insulating layer, as a whole, exhibit an optical transmittance of 50% or higher, excluding the area corresponding to the wiring pattern.

1 . A method for producing a semiconductor device, comprising:
 providing an insulating layer;   providing a conductor layer on a first side of said insulating layer, wherein a wiring pattern is to be formed in said conductor layer;   providing a releasing layer on a second side of said insulating layer, wherein the releasing layer is formed from a releasing agent,   wherein the releasing layer and the insulating layer, as a whole, exhibit an optical transmittance of 50% or higher, excluding the area corresponding to the wiring pattern;   mounting a semiconductor chip onto said wiring pattern by pressing a heating tool against said releasing layer so as to press said semiconductor chip provided on a chip stage to said wiring pattern.   
   
   
       2 . A method for producing a semiconductor device according to  claim 1 , wherein the releasing layer is formed by coating a solution containing the releasing agent to the insulating layer and heating. 
   
   
       3 . A method for producing a semiconductor device according to  claim 1 , wherein the releasing layer is formed by bringing a transfer film substrate, having the releasing layer formed thereon, into contact with a surface of the insulating layer, thereby transferring the releasing layer to the insulating layer, which surface is opposite to the mounting side of the semiconductor chip. 
   
   
       4 . A method for producing a semiconductor device according to  claim 1 , wherein the insulating layer is formed by coating a solution containing a polyimide precursor resin onto the conductor layer, drying the solution, and curing the resin. 
   
   
       5 . A method for producing a semiconductor device according to  claim 1 , wherein the insulating layer comprises a layer structure including an insulating film and a thermoplastic resin layer, wherein the structure is hot-press-adhered to the conductor layer. 
   
   
       6 . A method for producing a semiconductor device according to  claim 1 , wherein the insulating layer comprises a layer structure including an insulating film and a thermosetting resin layer, wherein the structure is hot-press-adhered to the conductor layer. 
   
   
       7 . A method for producing a semiconductor device according to  claim 1 , wherein the wiring pattern comprises a bond-improving layer sputtered on the insulating layer, and a metal plating layer provided on the bond-improving layer. 
   
   
       8 . A semiconductor device according to  claim 4 , wherein a row of sprocket holes is provided along at least one of opposite longitudinal edges of the wiring pattern, and the releasing layer is provided on a surface of the insulating layer between the rows of sprocket holes, which surface is opposite to the wiring pattern. 
   
   
       9 . A semiconductor device according to  claim 5 , wherein a plurality of sets of the wiring pattern and a row of sprocket holes provided along at least one of opposite longitudinal edges of the wiring pattern are provided such that the sets are juxtaposed in a width direction of the insulating layer.