High density integrated circuit module

Abstract

The present invention provides a method and apparatus for fabricating densely stacked ball-grid-array packages into a three-dimensional multi-package array. Integrated circuit packages are stacked on one another to form a module. Lead carriers provide an external point of electrical connection to buried package leads. Lead carriers are formed with apertures that partially surround each lead and electrically and thermally couple conductive elements or traces in the lead carrier to each package lead. Optionally thin layers of thermally conductive adhesive located between the lead carrier and adjacent packages facilitates the transfer of heat between packages and to the lead carrier. Lead carriers may be formed of custom flexible circuits having multiple layers of conductive material separated by a substrate to provide accurate impedance control and providing high density signal trace routing and ball-grid array connection to a printed wiring board.

1 - 41 . (canceled)  
   
   
       42 . A high density circuit module comprising: 
 first and second BGA packages, each having a body exhibiting a bottom surface, a top surface, a plurality of BGA contacts arranged in a grid along the bottom surface and first and second opposing lateral sides;    a flexible circuit having a first side with a first BGA-connecting portion including a plurality of electrical contacts arranged in a grid, and a second side, the first BGA-connecting portion of the first side of the flexible circuit being disposed below the body of the first BGA package and connected through the plurality of electrical contacts to the plurality of BGA contacts of the first BGA, the flexible circuit having a second portion having a second portion set of contacts for connecting to a circuit board and a third portion having a third portion set of contacts for connecting to the circuit board, the second portion being disposed partially beside the first lateral side of the second BGA package and the third portion being disposed partially beside the second lateral side of the second BGA package to dispose the second portion set of contacts and the third portion set of contacts below the level of a plane defined by the bottom surface of the body of the second BGA package.    
   
   
       43 . The high density circuit module of  claim 42  in which the flexible circuit comprises two or more planes of conductive material separated by high dielectric material.  
   
   
       44 . The high density circuit module of  claim 42  in which the plurality of electrical contacts are each formed having an aperture adapted to receive one of the BGA contacts.  
   
   
       45 . The high density circuit module of  claim 42  in which the flexible circuit is adhesively connected to the top surface of the second selected BGA package.  
   
   
       46 . A high density circuit module comprising: 
 a first BGA package having a body with a bottom surface, a top surface, a plurality of BGA contacts arranged in a grid along the bottom surface, and first and second opposing lateral sides that define a vertical extent of body;    a first flexible circuit having a first portion disposed above the top surface of the first BGA package, the first portion having a grid of electrical contacts, a second portion disposed beside the first lateral side of the first BGA package, a third portion disposed beside the second lateral side of the first BGA package, a fourth portion disposed adjacent to the second portion and below the vertical extent of the body of the first BGA package, the fourth portion having a first set of contacts for connecting to a circuit board, a fifth portion disposed adjacent to the third portion and below the vertical extent of the body of the first BGA package, the fifth portion having a second set of contacts for connecting to the circuit board;    a second BGA package having a body with a bottom surface, a top surface, a plurality of BGA contacts arranged in a grid along the bottom surface, and first and second opposing lateral sides that define a vertical extent of body, the second BGA package being mounted to the grid of electrical contacts, the second BGA package being above the first BGA package.    
   
   
       47 . The high density circuit module of  claim 46  in which the first flexible circuit comprises two or more planes of conductive material separated by high dielectric material.  
   
   
       48 . The high density circuit module of  claim 46  further comprising: 
 a second flexible circuit having a first portion disposed above the top surface of the second BGA package, the first portion having a grid of electrical contacts, a second portion disposed beside the first lateral side of the second BGA package, a third portion disposed beside the second lateral side of the second BGA package, a fourth portion disposed adjacent to the second portion and below the vertical extent of the body of the second BGA package, the fourth portion having a first set of contacts for connecting to the first flexible circuit, a fifth portion disposed adjacent to the third portion and below the vertical extent of the body of the second BGA package, the fifth portion having a second set of contacts for connecting to the first flexible circuit;    a third BGA package having a body with a bottom surface, a top surface, a plurality of BGA contacts arranged in a grid along the bottom surface, and first and second opposing lateral sides that define a vertical extent of body, the third BGA package being mounted to the grid of electrical contacts of the second flexible circuit, the third BGA package being above the second BGA package.    
   
   
       49 . The high density circuit module of  claim 46  in which the grid of electrical contacts are each formed having an aperature adapted to receive one of the BGA contacts.  
   
   
       50 . The high density circuit module of  claim 46  in which the flexible circuit is adhesively connected to the top surface of the second selected BGA package.  
   
   
       51 . The high density circuit module of  claim 46  in which the flexible circuit is adhesively connected to the top surface of the second selected BGA package.