Stacked Modules and Method

Abstract

The present invention stacks integrated circuits into modules that conserve board surface area. In a precursor assembly devised as a component for a stacked circuit module in accordance with a preferred embodiment of the present invention, one or more stiffeners are disposed at least partially between a flex circuit and an integrated circuit. In a two-high stacked circuit module devised in accordance with a preferred embodiment of the present invention, an integrated circuit is stacked above a precursor assembly. The two integrated circuits are connected with the flex circuit of the precursor assembly. The present invention may be employed to advantage in numerous configurations and combinations of integrated circuits in modules.

1 . A method for constructing an assembly devised for employment in a stacked circuit module, the method comprising the steps of: 
 providing a first CSP comprising upper and lower major surfaces and first CSP contacts disposed along the lower major surface;    providing a flex circuit comprising lower flex contacts, and first and second upper portions terminated by first and second edges, respectively;    providing a stiffener;    attaching the stiffener to the flex circuitry;    attaching the stiffener to the lower major surface of the first CSP;    disposing the first and second upper portions of the flex circuitry above the upper major surface of the first CSP; and    imposing a preselected distance between the first and second edges.    
   
   
       2 . The method of  claim 1  in which a physical form is used to impose a preselected distance between the first and second edges.  
   
   
       3 . The method of  claim 2  in which a portion of the physical form is placed between the first and second edges.  
   
   
       4 . The method of  claim 1  in which the flex circuit comprises a fiducial, the method further comprising the steps of referring the fiducial and disposing the first CSP along the flex circuit.  
   
   
       5 . The method of  claim 1  in which the stiffener is provided in a first aggregation having other stiffeners and the flex circuit is provided in a second aggregation having other flex circuits, the method further comprising the steps of referring to a fiducial comprised in the second aggregation and singulating the assembly from the first and second aggregations.  
   
   
       6 . The method of  claim 5  in which the second aggregation comprises a trim tab having conductive bussing, the flex circuit of the assembly has an end portion having no conductive bussing, and the step of singulating comprises the steps of separating the trim tab from the flex circuit of the assembly and separating end portion of the flex circuit of the assembly from the second aggregation.  
   
   
       7 . A method for constructing a stacked circuit module, the method comprising the steps of: 
 constructing an assembly devised for employment in a stacked circuit module in accordance with  claim 1;     providing a second CSP; and    disposing the second CSP above the assembly and connecting the second CSP to the flex circuit.    
   
   
       8 . A method for constructing an assembly devised for employment in a stacked circuit module, the method comprising the steps of: 
 providing a tooling apparatus;    disposing a CSP, a stiffener, and a flex circuit in a cavity of the tooling apparatus to deflect a first upper portion and a second upper portion of the flex circuit upward; and    disposing the first and second upper portions of the flex circuit along an upper surface of the CSP with the forming tool.    
   
   
       9 . The method for constructing an assembly of  claim 8  in which the tooling apparatus further comprises a physical form, the method further comprising the step of using the physical form to impose a preselected distance between a first edge and a second edge of the flex circuit.  
   
   
       10 . The method for constructing an assembly of  claim 9  in which the tooling apparatus further comprises a press tool, the method further comprising the step of using the press tool to impose the first and second upper portions of the flex circuit on an upper surface of the CSP.  
   
   
       11 . The method for constructing an assembly of  claim 10 , the method further comprising the step of heating the press tool.  
   
   
       12 . A method for constructing an assembly devised for employment in a stacked circuit module, the method comprising the steps of: 
 providing a tooling apparatus;    adjusting a jig of the tooling apparatus to a first configuration;    disposing a CSP, a stiffener, and a flex circuit in a cavity of the tooling apparatus    using a preform tool to deflect a first upper portion and a second upper portion of the flex circuit upward to a first flex configuration;    adjusting the jig to a second configuration; and    disposing the CSP, the stiffener, and the flex circuit in the cavity of the tooling apparatus to deflect the first upper portion and the second upper portion of the flex circuit upward to a second flex configuration.    
   
   
       13 . The method for constructing an assembly of  claim 12  in which the tooling apparatus further comprises a physical form, the method further comprising the step of using the physical form to impose a preselected distance between a first edge and a second edge of the flex circuit.  
   
   
       14 . The method for constructing an assembly of  claim 13  in which the tooling apparatus further comprises a press tool, the method further comprising the step of using the press tool to impose the first and second upper portions of the flex circuit on an upper surface of the CSP.  
   
   
       15 . The method for constructing an assembly of  claim 14 , the method further comprising the step of heating the press tool.  
   
   
       16 . The method for constructing an assembly of  claim 13  in which the tooling apparatus further comprises a forming tool, the method further comprising the step of disposing the first and second upper portions of the flex circuit along an upper surface of the CSP with the forming tool.