Thermal bonding structure and manufacture process of flexible printed circuit board

Abstract

A thermal bonding structure and manufacture process of a flexible printed circuit (FPC) board are disclosed, and the thermal bonding structure includes a laminated structure having a first insulating layer with a solder pad area and showing parts of a first conductive layer, the first conductive layer, a second insulating layer, a second conductive layer, and a third insulating layer with a bonding area such that a part of the second conductive layer is exposed, and at least a through hole passing through the first conductive layer to the second conductive layer for propagating heat energy to fuse a solder. Accordingly, the reduction of heat energy lost in the third insulating layer improves the bonding quality, shortens the bonding period, and maintains the material stability under high temperature resulted from high heat energy.

1 . A method for manufacturing a flexible printed circuit board, comprising the steps of:
 providing a laminated structure having a first insulating layer, a first conductive layer, a second insulating layer, a second conductive layer and a third insulating layer laminated in sequence;   dividing the laminated structure into a first portion, a second portion and a third portion, wherein the second portion is between the first portion and the third portion;   forming at least one through hole in the second insulating layer of the first portion and the third portion, respectively;   forming a solder pad area by removing a part of the first insulating layer of the third portion to expose the first conductive layer; and   forming a bonding area by removing a part of the third insulating layer of the third portion to expose the second conductive layer, wherein the at least one through hole is formed beyond the range of the solder pad area and the bonding area.   
   
   
       2 . The method of  claim 1 , further comprising a step of:
 removing the second conductive layer and the third insulating layer of the second portion.   
   
   
       3 . The method of  claim 1 , wherein the step of forming at least one through hole further comprises a step of:
 forming a conductive material in the at least one through hole.   
   
   
       4 . The method of  claim 1 , wherein the first conductive layer and the second conductive layer are comprised of copper. 
   
   
       5 . The method of  claim 1 , further comprising a step of:
 forming an adhesive layer disposed between the first insulating layer and the first conductive layer.   
   
   
       6 . The method of  claim 1 , further comprising a step of:
 forming an adhesive layer disposed between the first conductive layer and the second insulating layer.   
   
   
       7 . The method of  claim 1 , further comprising a step of:
 forming an adhesive layer disposed between the second insulating layer and the second conductive layer.   
   
   
       8 . The method of  claim 1 , further comprising a step of:
 forming an adhesive layer disposed between the second conductive layer and the third insulating layer.