CSP chip stack with flex circuit

Abstract

A chip stack comprising a flex circuit including a flex substrate having a first conductive pattern disposed thereon and a plurality of leads extending therefrom. Also included in the chip stack are at least two integrated circuit chip packages. The integrated circuit chip packages may be electrically connected to the first conductive pattern of the flex circuit such that the integrated circuit chip packages are positioned upon respective ones of opposed top and bottom surfaces of the flex substrate. Alternatively, one of the integrated circuit chip packages may be positioned upon the top surface of the flex substrate and electrically connected to the first conductive pattern, with the remaining integrated circuit chip package being attached in a non-conductive manner to the bottom surface of the flex substrate such that the conductive contacts of such integrated circuit chip package and the leads collectively define a composite footprint for the chip stack.

1 . A stacked circuit module that presents a composite footprint, the stacked circuit module comprising: 
 a flexible circuit having a conductive pattern comprised of flex pads and a plurality of conductive leads;    a first integrated circuit chip package having a rectangular body with a planar top surface and planar bottom surface and disposed along the planar bottom surface there being a plurality of conductive contacts;    a second integrated circuit chip package having a rectangular body with a planar top surface and a planar bottom surface and disposed along the planar bottom surface there being a plurality of conductive contacts, the first and second integrated circuit chip packages being disposed on opposite sides of the flexible circuit and oriented so that the plurality of conductive contacts of the first integrated circuit chip package face toward the flexible circuit while the plurality of conductive contacts of the second integrated circuit chip package face away from the flexible circuit so that the stacked circuit module presents as a composite footprint both the plurality of conductive contacts of the second integrated circuit chip package and the plurality of conductive leads of the flexible circuit.    
   
   
       2 . The stacked circuit module of  claim 1  in which the plurality of conductive leads of the flexible circuit comprises a J-lead.  
   
   
       3 . The stacked circuit module of  claim 1  in which the plurality of conductive leads of the flexible circuit comprises an S-lead.  
   
   
       4 . The stacked circuit module of  claim 1  in which the plurality of conductive leads of the flexible circuit comprises a gull-wing lead.  
   
   
       5 . The stacked circuit module of  claim 1  further comprising an I/O transposer.  
   
   
       6 . The stacked circuit module of  claim 5  in which the I/O transposer is comprised of PCB.  
   
   
       7 . The stacked circuit module of  claim 1  in which the first and second integrated circuit chip packages are each CSP devices.  
   
   
       8 . The stacked circuit module of  claim 1  in which the first and second integrated circuit chip packages are each BGA devices.  
   
   
       9 . The stacked circuit module of  claim 1  in which the first and second integrated circuit chip packages are each flip-chip devices.  
   
   
       10 . A stacked circuit module comprising: 
 a flexible circuit having a first conductive pattern comprised of flex pads and a second conductive pattern comprised of flex pads;    a first integrated circuit chip package having a rectangular body with a planar top surface and planar bottom surface and disposed along the planar bottom surface there being a plurality of conductive contacts;    a second integrated circuit chip package having a rectangular body with a planar top surface and a planar bottom surface and disposed along the planar bottom surface there being a plurality of conductive contacts, the first and second integrated circuit chip packages being disposed on opposite sides of the flexible circuit and oriented with the respective pluralities of conductive contacts of each of the first and second integrated circuit chip packages facing toward each other with the flexible circuit therebetween.    
   
   
       11 . The stacked circuit module of  claim 10  in which the flex pads of the first conductive pattern and the flex pads of the second conductive pattern are coaxially arranged in identical patterns.  
   
   
       12 . The stacked circuit module of  claim 10  in which the flexible circuit has a plurality of conductive leads.  
   
   
       13 . The stacked circuit module of  claim 12  in which at least one of the plurality of conductive leads is electrically connected to at least one flex pad of the first conductive pattern.  
   
   
       14 . The stacked circuit module of  claim 12  in which at least one of the plurality of conductive leads is electrically connected to at least one flex pad of the second conductive pattern.  
   
   
       15 . The stacked circuit module of  claim 10  in which at least one flex pad of the first conductive pattern and at least one flex pad of the second conductive pattern are electrically connected.  
   
   
       16 . The stacked circuit module of  claim 10  in which two or more flex pads of a first set of the plurality of flex pads of the first conductive pattern of the flex circuit are electrically connected to a single one of the plurality of conductive leads of the flexible circuit.  
   
   
       17 . The stacked circuit module of  claim 12  in which the plurality of conductive leads comprises an S-lead.  
   
   
       18 . The stacked circuit module of  claim 12  in which the plurality of conductive leads comprises a gull-wing lead.  
   
   
       19 . The stacked circuit module of  claim 10  in which the first and second integrated circuit chip packages each are CSPs.  
   
   
       20 . The stacked circuit module of  claim 10  in which the first and second integrated circuit chip packages each are flip-chip devices.  
   
   
       21 . The stacked circuit module of  claim 10  in which the first and second integrated circuit chip packages are each BGA devices.