Methods of flip-chip image sensor package fabrication

Abstract

The present invention provides flip-chip packaging for optically interactive devices such as image sensors and methods of assembly. In a first embodiment of the invention, conductive traces are formed directly on the second surface of a transparent substrate and an image sensor chip is bonded to the conductive traces. Discrete conductive elements are attached to the conductive traces and extend below a back surface of the image sensor chip. In a second embodiment, a secondary substrate having conductive traces formed thereon is secured to the transparent substrate. In a third embodiment, a backing cap having a full array of attachment pads is attached to the transparent substrate of the first embodiment or the secondary substrate of the second embodiment. In a fourth embodiment, the secondary substrate is a flex circuit having a mounting portion secured to the second surface of the transparent substrate and a backing portion bent over adjacent to the back surface of the image sensor chip.

1 . A method for fabricating an electronic device package comprising: 
 forming a plurality of conductive traces on a surface of a transparent substrate, each conductive trace of the plurality of conductive traces extending between a first attachment point and a second attachment point;    providing at least one optically interactive electronic device having at least one bond pad on an active surface thereof;    bonding the at least one bond pad of the at least one optically interactive electronic device to the first attachment point of a conductive trace of the plurality of conductive traces;    sealing a volume between a portion of the active surface of the at least one optically interactive electronic device and the transparent substrate from the outside environment with a polymer sealant material; and    providing a discrete conductive element on the second attachment point of the conductive trace such that the discrete conductive element extends outwardly from the second attachment point in a direction perpendicular to a plane of the surface of the transparent substrate and to a level beyond a back side surface of the at least one optically interactive electronic device.    
   
   
       2 . The method of  claim 1 , wherein forming a plurality of conductive traces on a surface of a transparent substrate comprises forming the second attachment points of the plurality of conductive traces in at least one row extending adjacent a perimeter location of the at least one optically interactive electronic device.  
   
   
       3 . The method of  claim 2 , further comprising: 
 forming the second attachment points of the plurality of conductive traces in multiple rows extending adjacent the perimeter location of the at least one optically interactive electronic device.    
   
   
       4 . The method of  claim 1 , wherein forming a plurality of conductive traces on a surface of a transparent substrate comprises: 
 disposing a conductive or conductor-filled material onto the surface of the transparent substrate in a pattern defining the plurality of conductive traces.    
   
   
       5 . The method of  claim 1 , wherein forming a plurality of conductive traces on a surface of a transparent substrate comprises: 
 disposing a layer of conductive material on the surface of the transparent substrate; and selectively etching the conductive material to define the plurality of conductive traces.    
   
   
       6 . The method of  claim 1 , wherein sealing the portion of the active surface comprises depositing a bead of polymer sealant material on the surface of the transparent substrate along at least one side of the at least one optically interactive electronic device and in contact therewith.  
   
   
       7 . The method of  claim 1 , further comprising selecting the discrete conductive element to comprise one of a solder ball, a solder column, a conductive epoxy, and a conductor-filled epoxy.  
   
   
       8 . The method of  claim 1 , further comprising selecting the at least one optically interactive electronic device to comprise an image sensor.  
   
   
       9 . The method of  claim 1 , further comprising: 
 selecting the at least one optically interactive electronic device to comprise a plurality of optically interactive electronic devices; and    dividing the transparent substrate between the optically interactive electronic devices of the plurality to provide individual electronic device packages.    
   
   
       10 . A method for fabricating an electronic device package comprising: 
 forming a plurality of conductive traces on a surface of a transparent substrate, each conductive trace of the plurality of conductive traces having a first attachment point and a second attachment point;    providing an optically interactive electronic device having at least one bond pad on an active surface thereof;    bonding the at least one bond pad of the optically interactive electronic device to the first attachment point of a conductive trace of the plurality of conductive traces;    sealing a portion of the active surface of the optically interactive electronic device from the outside environment with a polymer sealant material; and    providing a discrete conductive element on the second attachment point of the conductive trace such that the discrete conductive element extends outwardly from the second attachment point in a direction perpendicular to a plane of the surface of the transparent substrate and to a level beyond a back side surface of the optically interactive electronic device.    
   
   
       11 . The method of  claim 10 , wherein sealing the portion of the active surface comprises depositing a bead of silicone sealant material on the surface of the transparent substrate along at least one side of the optically interactive electronic device and in contact therewith.  
   
   
       12 . The method of  claim 10 , further comprising selecting the discrete conductive element to comprise one of a solder ball, a solder column, a conductive epoxy, and a conductor-filled epoxy.  
   
   
       13 . The method of  claim 10 , further comprising selecting the polymer sealant material to comprise one of silicone and epoxy.