Solder in cavity interconnection technology

Abstract

An interconnection technology may use molded solder to define solder balls. A mask layer may be patterned to form cavities and solder paste deposited in the cavities. Upon heating, solder balls are formed. The cavity is defined by spaced walls to keep the solder ball from bridging during a bonding process. In some embodiments, the solder bumps connected to the solder balls may have facing surfaces which are larger than the facing surfaces of the solder ball.

What is claimed is: 
     
         1 . An apparatus comprising:
 a substrate;   a plurality of solder bumps formed on the substrate;   walls extending from the substrate defining cavities which separate the plurality of solder bumps from one another, wherein the walls are 50 to 100 microns taller than the solder bumps; and   a plurality of solder balls formed on each respective solder bump, wherein at least one solder ball is entirely contained within its respective cavity.   
     
     
         2 . The apparatus of  claim 1 , wherein the cavities have a depth of about 200 to 250 microns. 
     
     
         3 . The apparatus of  claim 1 , wherein the walls overlap a portion of each of the plurality solder bumps. 
     
     
         4 . The apparatus of  claim 1 , wherein at least one of the plurality of solder balls has a facing surface that is less than or equal to a facing surface of the solder bump. 
     
     
         5 . The apparatus of  claim 1 , wherein said solder balls have a dimension that is at least 75 percent of an interconnection pitch. 
     
     
         6 . The apparatus of  claim 1 , wherein said solder bumps are at least 70 percent of an interconnection pitch. 
     
     
         7 . The apparatus of  claim 1 , including at least one cavity having a size differing from at least one other cavity. 
     
     
         8 . The apparatus of  claim 1 , further comprising at least one solder ball extending beyond its respective cavity. 
     
     
         9 . The apparatus of  claim 1 , wherein the walls comprise at least two layers. 
     
     
         10 . The apparatus of  claim 1 , further including a device having at least one protrusion that penetrates at least one cavity to connect with a solder ball therein. 
     
     
         11 . A method comprising:
 forming a substrate;   forming a plurality of solder bumps on the substrate;   forming walls to extend from the substrate defining cavities which separate the plurality of solder bumps from one another, wherein the walls are 50 to 100 microns taller than the solder bumps; and   forming a plurality of solder balls on each respective solder bumps, wherein at least one solder ball is entirely contained within its respective cavity.   
     
     
         12 . The method of  claim 11 , wherein defining the cavities comprises defining the cavities to have a depth of about 200 to 250 microns. 
     
     
         13 . The method of  claim 11 , wherein the forming walls comprises forming walls to overlap a portion of each of the plurality solder bumps. 
     
     
         14 . The method of  claim 11 , wherein forming the plurality of solder balls further comprises forming at least one of the plurality of solder balls to have a facing surface that is less than or equal to a facing surface of the solder bump. 
     
     
         15 . The method of  claim 11 , wherein forming the plurality of solder balls comprises forming the plurality of solder balls to have a dimension that is at least 75 percent of an interconnection pitch. 
     
     
         16 . The method of  claim 11 , wherein forming the plurality of solder bumps comprises forming the plurality of solder bumps to be at least 70 percent of an interconnection pitch. 
     
     
         17 . The method of  claim 11 , wherein defining the cavities comprises defining cavities of different sizes. 
     
     
         18 . The method of  claim 11 , further comprising forming at least one of the plurality of solder balls to extend beyond its respective cavity. 
     
     
         19 . The method of  claim 11 , wherein forming the solder balls comprising molding a solder paste in the cavities. 
     
     
         20 . The method of  claim 19 , wherein molding the solder paste comprise forming the solder paste comprising a powder having a diameter less than or equal to one-seventh of a depth of the cavity. 
     
     
         21 . The method of  claim 19 , further comprising reflowing the solder paste to form a solder ball that wets the solder bump. 
     
     
         22 . The method of  claim 11  including forming a material on said solder bump to limit wetting of solder. 
     
     
         23 . The method of  claim 11 , wherein forming the walls comprises forming the walls to comprise at least two layers. 
     
     
         24 . The method of  claim 23 , wherein forming the walls comprise forming a stacked outer and inner layer and removing the outer layer without removing the inner layer. 
     
     
         25 . The method of  claim 24 , wherein forming the plurality of solder balls includes forming at least one of the plurality of solder balls to be taller than said inner layer. 
     
     
         26 . A method comprising:
 aligning a first component comprising a substrate having a plurality of solder bumps thereon and walls extending from the substrate defining cavities which separate the plurality of solder bumps from one another, wherein the walls are 50 to 100 microns taller than the solder bumps, and a second component including at least one land to connect to at least one of the plurality of solder balls of the first component;   applying pressure to one of the first component and the second component; and   reflowing the plurality of solder balls to connect at least one of the plurality of solder balls to at least one of the second component lands.   
     
     
         27 . The method of  claim 26 , further including applying pressure so that the at least one second component land penetrates into at least one of the first component solder balls.