Rigid-flexible printed circuit board for package on package and manufacturing method

Abstract

The present invention relates to a rigid-flexible multi-layer printed circuit board comprising: a flexible substrate of which circuits are formed on both sides and which is bendable; a rigid substrate which is laminated on the flexible substrate and circuits are formed on both sides and a cavity within which a semiconductor chip is mounted is formed; and a bonding sheet adhering the flexible substrate and the rigid substrate and having a insulating property. According the present invention, when the same numbers of the semiconductor chips are mounted or the POP is embodied, the whole thickness of the package can be lower. Also, two more semiconductor chips can be mounted using the space as the thickness of the core layer, and the structure impossible when the number of semiconductor chip mounted on the bottom substrate becomes two from one in conventional technology can be embodied.

1 . A rigid-flexible multi-layer printed circuit board comprising: 
 a flexible substrate of which circuits are formed on both sides and which is bendable;    a rigid substrate having a cavity which is laminated on the flexible substrate and of which circuits are formed on both sides and semiconductor chips can be mounted in the cavity; and    a bonding sheet adhering the flexible substrate and the rigid substrate and having a insulating property.    
   
   
       2 . The rigid-flexible multi-layer printed circuit board of  claim 1 , wherein the rigid substrate is thicker than the flexible substrate.  
   
   
       3 . The rigid-flexible multi-layer printed circuit board of  claim 1 , wherein wire bonding pads for electrical connection with the semiconductor chips are formed on the flexible substrate within the cavity and on the rigid substrate of the edge of opening part of the cavity.  
   
   
       4 . The rigid-flexible multi-layer printed circuit board of  claim 1 , wherein the flexible substrate and the rigid substrate are connected electrically therebetween through inner via holes or blind via holes.  
   
   
       5 . The rigid-flexible multi-layer printed circuit board of  claim 1 , wherein a plurality of the rigid substrates having the cavity are laminated with a predetermined gap on the flexible substrate and package on package (POP) is formed by folding the flexible substrate having the predetermined gap after semiconductor chips are mounted within the cavity.  
   
   
       6 . A method for manufacturing a multi-layer rigid-flexible printed circuit board comprising: 
 (a) forming a single circuit on a flexible substrate;    (b) laminating a rigid substrate having a circuit and a cavity on the flexible substrate;    (c) drilling via holes interconnecting the flexible substrate and the rigid substrate;    (d) plating the via holes;    (e) forming an outer circuit on a laminate of the flexible substrate and the rigid substrate; and    (f) forming wire bonding pads for electrical connection with semiconductor chips on the flexible substrate within the cavity and on the rigid substrate of the edge of the opening part of the cavity.    
   
   
       7 . The method for manufacturing a multi-layer rigid-flexible printed circuit board of  claim 6 , wherein at the step (a), the single circuit is formed through a roll to roll process on the flexible substrate.  
   
   
       8 . The method for manufacturing a multi-layer rigid-flexible printed circuit board of  claim 6 , wherein the step (b) comprises: forming the cavity on the rigid substrate by using a punch or a router.  
   
   
       9 . The method for manufacturing a multi-layer rigid-flexible printed circuit board of  claim 6 , wherein the step (b) further comprises (b- 1 ) laminating with pressure by using a bonding sheet between the flexible substrate and the rigid substrate.  
   
   
       10 . The method for manufacturing a multi-layer rigid-flexible printed circuit board of  claim 9 , wherein the flexible substrate and the rigid substrate are laminated on a desired position using a rivet or a pin.  
   
   
       11 . The method for manufacturing a multi-layer rigid-flexible printed circuit board of  claim 9 , wherein before the step (b- 1 ), laminating a conformal film is further comprised so that the bonding sheet does not cover the wire bonding pads.  
   
   
       12 . The method for manufacturing a multi-layer rigid-flexible printed circuit board of  claim 6 , wherein in the step (b), a plurality of the rigid substrates are laminated on the flexible substrate with a predetermined gap, and 
 after the step (f),    (g) mounting a plurality of semiconductor chips within the each cavity, and    (h) folding and molding the flexible substrate laminated with the predetermined gap are further comprised.