Plated via interposer

Abstract

An interposer with a contact well, a layer that isolates one side of the interposer from the other side, for isolations of off gasses, and an optional elastomeric pad and a hard stop layer. Included is a method of making the interposer.

1 . An interposer, for providing electrical connection between a contact of one electrical component and a contact of another electrical component: 
 an insulative planar layer with an upper surface and a lower surface, which defines a plurality of vias which penetrate said insulative planar layer;    an interposer body, comprising an upper contact pad of copper positioned on said upper surface of said insulative planar sheet, with a plurality of connecting posts which fill said vias and which penetrate said insulative planar sheet and are contiguous with said upper contact pad, and contiguous with a lower contact pad of copper positioned on said lower surface of said insulative planar sheet, with said upper contact pad comprising one or more outer sidewalls and one or more inner sidewalls and a top contact surface, with said inner sidewalls defining a well, for centering contact with a contact ball, in which said insulative planer is not penetrated below said well.    
   
   
       2 . The interposer of  claim 1  which further includes an elastomeric pad attached to said lower contact surface, in which said elastomeric pad includes metallic granules which conduct electricity through said elastomeric pad, and in which said elastomeric pad is compressible and conductive.  
   
   
       3 . The interposer of  claim 2 , which further includes an expansion limiter for each elastomeric pad to limit the amount each elastomeric pad may expand under pressure by surrounding said elastomeric pad by a material with less expansion potential.  
   
   
       4 . The interposer of  claim 3 , in which said expansion limiter is a hard stop layer, attached to said lower surface of said insulative layer, in which said hard stop layer defines one or more passages through which said elastomeric pads extend, with said hard stop layer being less thick than the height of said elastomeric pads, with hard stop layer provided to limit the possible expansion of said elastomeric pads under compression.  
   
   
       5 . The interposer of  claim 4  in which said passages of said hard stop layer are configured to provide a gap between a passage side wall and said elastomeric pad, in which gap said elastomeric pad may expand.  
   
   
       6 . The interposer of  claim 1  which further includes a contact edge formed by the interface between said inner walls and said top contact surface  
   
   
       7 . The interposer of  claim 1  in which said one or more inner side walls form a generally rectangular well.  
   
   
       8 . The interposer of  claim 1  in which said one or more outer side walls form a generally rectangular upper contact pad.  
   
   
       9 . The interposer of  claim 1  in which said vias are made by laser cutting of said insulative layer.  
   
   
       10 . The interposer of  claim 1  in which the distance from the center of one contact pad to an adjacent contact pad is less than 0.75 mm.  
   
   
       11 . The interposer of  claim 1  in which the distance from the center of one contact pad to an adjacent contact pad is less than 0.65 mm.  
   
   
       12 . The interposer of  claim 1  in which the distance from the center of one contact pad to an adjacent contact pad is less than 0.50 mm.  
   
   
       13 . The interposer of  claim 1  which includes one or more layers of conductive metal on one or more of said contact surfaces.  
   
   
       14 . The interposer of  claim 12  in which said contact surfaces are coated with a layer of nickel.  
   
   
       15 . The interposer of  claim 12  in which said contact surfaces are coated with a layer of gold.