Mold fill improvements for a molded solder C4 process

Abstract

A mold fill system includes a fill head, at least one solder input port, at least one solder output port, disposed on the leading edge of the fill head body, a mold plate, the fill head body being held near the mold plate, including a plurality of mold pits for injection molded solder and at least one o-ring disposed between the fill head body and the mold plate, for sealing the solder between the fill head body and the mold plate. An input velocity of the solder is sufficient to dislodge air trapped within the mold pits, and a circulartion pump is disposed on either a fill side or a return side of the fill head body to re-circulate the solder between the solder reservoir and the fill head. Optionally, heated plumbing connects the circulation pump, the fill head and the reservoir.

1 . A mold fill system, comprising:
 a fill head, having a leading edge and a trailing edge;   at least one solder input port, for receiving solder from a solder reservoir;   at least one solder output port;   a mold plate, said fill head being disposed adjacent to said mold plate, said solder flowing through said fill head, through said at least one solder input port and onto said mold plate, said mold plate including a plurality of mold pits for injection molded solder; and   at least one seal disposed between said fill head and said mold plate, said at least one seal sealing said solder in a solder fill zone disposed between said fill head body and said mold plate,   wherein an input flow velocity of said solder is sufficient to dislodge at least a portion of air trapped within said mold pits, and   wherein at least one circulation pump is disposed on at least one of a fill side and a return side of the fill head body to re-circulate said solder between said solder reservoir and said fill head.   
   
   
       2 . The mold fill system according to  claim 1 , wherein a flow cross-sectional area is smaller than an inlet flow cross-sectional area. 
   
   
       3 . The mold fill system according to  claim 1 , wherein said solder flows uniformly across a width of said fill head. 
   
   
       4 . The mold fill system according to  claim 1 , further comprising:
 a cold element, cooled by a liquid or a gas coolant, disposed on a trailing edge of said fill head to cool and solidify the solder,   wherein said cold element is thermally insulated from a remainder of the mold fill system.   
   
   
       5 . The mold fill system according to  claim 1 , further comprising:
 a vacuum disposed on the leading edge of said fill head to reduce an amount of air contained within said molded pits.   
   
   
       6 . The mold fill system according to  claim 1 , further comprising:
 a vibrating transducer for agitating the molded fill system.   
   
   
       7 . The mold fill system according to  claim 1 , wherein said at least one circulation pump, said fill head and said reservoir are connected by heated plumbing.