Reliable printed wiring board assembly employing packages with solder joints and related assembly technique

Abstract

An exemplary assembly comprises a printed wiring board having a first surface, and a package including a plurality of solder joints, such as solder balls, on one surface of the package. An anchor via is defined through the first surface of the printed wiring board, and conductive material situated in the anchor via is connected to or integral with a respective solder joint of the package.

1 . A method for assembling a package to a printed wiring board, the printed wiring board having a first surface, the package including a plurality of solder balls on at least one surface of the package, the method comprising: 
 forming an anchor via through the first surface of the printed wiring board;    mounting the package on the printed wiring board such that at least one of the plurality of solder balls contact an opening of the anchor via;    melting the that at least one of the plurality of solder balls so that a portion of the at least one of the plurality of solder balls fills at least a portion of the anchor via.    
     
     
         2 . The method of  claim 1 , wherein the at least one of the plurality of solder balls is situated proximate a periphery of the at least one surface of the package.  
     
     
         3 . The method of  claim 1 , wherein the at least one of the plurality of solder balls is situated proximate a corner of the at least one surface of the package.  
     
     
         4 . The method of  claim 1 , wherein the portion of the at least one of the plurality of solder balls situated within the anchor via comprises an isolated conductor.  
     
     
         5 . The method of  claim 1 , wherein the anchor via extends through the printed wiring board to an intermediate metal layer segment of the printed wiring board, the intermediate metal layer segment comprising an isolated metal layer segment.  
     
     
         6 . The method of  claim 1 , wherein the forming the anchor via step comprises drilling through the first surface of the printed wiring board.  
     
     
         7 . The method of  claim 1 , wherein the melting step comprises a reflow process.  
     
     
         8 . The method of  claim 1 , wherein the forming the anchor via step comprises drilling through the first surface of the printed wiring board without drilling to an intermediate metal layer of the printed wiring board.