Positioning flowable solder for bonding integrated circuit elements

Abstract

A solder mask defined bond pad or a non-solder mask defined bond pad may be configured to center the solder over the bond pad using either surface attractive forces or capillary action. In some embodiments, a stub trace may be provided, for example, in opposition to the real trace to provide a capillary counter-attractive force on the solder. In other embodiments, the surface attractive action of the edge of the solder mask may be utilized to center the solder. In still other embodiments, the natural attractive force of a trace on solder may be utilized to appropriately position solder where desired, for example, to line up with other solder deposits.

1 . A method of positioning solder on bond pads: coupled to traces, said bond pads being surrounded by solder mask material, said method comprising: 
 depositing solder on a first bond pad having a trace extending in a first direction;    depositing solder on a second bond pad having a trace extending in a second direction, said first and second directions being different; and    causing said solder deposited on said first bond pad to move to a displaced position with respect to said first bond pad, such that said solder aligns with said solder deposited on said second bond pad.    
     
     
         2 . The method of  claim 1  including nesting said first bond pad with a trace coupled to said second bond pad, and nesting said second bond pad with a trace coupled to said first bond pad.  
     
     
         3 . The method of  claim 1  wherein causing includes wicking said solder towards a trace coupled to said first bond pad.  
     
     
         4 . A method of forming solder connections in integrated circuits comprising: 
 depositing solder on a bond pad;    counteracting an attractive force supplied by a bond pad trace to the solder by providing a similar and opposite force on the solder.    
     
     
         5 . The method of  claim 4  wherein counteracting includes forming a trace-like portion which extends away from said bond pad in a direction opposite to the direction that the trace extends away from said bond pad.  
     
     
         6 . The method of  claim 5  wherein counteracting includes forming a solder mask around said bond pad and causing said trace-like element to extend outwardly from said bond pad into said solder mask.  
     
     
         7 . The method of  claim 4  wherein counteracting includes forming tear-drop shaped portions on two opposed sides of a bond pad.  
     
     
         8 . The method of  claim 4  further including providing elements which tend to cause said solder to center on said bond pad.  
     
     
         9 . The method of  claim 8  further including providing a set of three elements coupled to said bond pad and oriented at approximately 90° to an adjacent element.