Apparatus and process for manufacturing solder balls

Abstract

An apparatus and method of forming fluxless solder balls includes forming solder balls from a supply of solder. A coating is formed on the solder balls for limiting naturally occurring oxide growth on the solder balls before significant natural oxide growth on the solder balls has occurred. The coating allows the solder balls to be soldered without using flux.

What is claimed is:  
     
         1 . A method of forming fluxless solder balls comprising: 
 forming solder balls from a supply of solder; and    forming a coating on the solder balls for limiting naturally occurring oxide growth on the solder balls before significant natural oxide growth on the solder balls has occurred, the coating allowing the solder balls to be soldered without using flux.    
     
     
         2 . The method of  claim 1  further comprising forming the solder balls from molten solder.  
     
     
         3 . The method of  claim 2  further comprising forming the solder balls by a droplet spray process wherein the molten solder is caused to fall as droplets which solidify while falling to form the solder balls.  
     
     
         4 . The method of  claim 3  further comprising forming the coating on the solder balls while the solder balls are falling.  
     
     
         5 . The method of  claim 4  in which forming the coating on the solder balls comprises treating the solder balls with plasma products.  
     
     
         6 . The method of  claim 5  further comprising including fluorine within the plasma products.  
     
     
         7 . The method of  claim 6  further comprising forming an oxyfluoride layer on the solder balls.  
     
     
         8 . The method of  claim 5  further comprising forming the solder balls at a solder ball forming station.  
     
     
         9 . The method of  claim 8  further comprising coating the solder balls at a coating station.  
     
     
         10 . The method of  claim 9  in which the coating station comprises a chamber containing the plasma products therein.  
     
     
         11 . The method of  claim 10  further comprising supplying the chamber with the plasma products from a plasma generator.  
     
     
         12 . The method of  claim 11  further comprising supplying the plasma generator with a gas containing fluorine.  
     
     
         13 . A method of forming fluxless solder balls comprising: 
 forming solder balls by a droplet spray process wherein molten solder is caused to fall as droplets which solidify while falling to form the solder balls; and    forming a coating on the solder balls before significant natural oxide growth on the solder balls has occurred by treating the solder balls with plasma products while the solder balls are falling, the coating limiting naturally occurring oxide growth on the solder balls and allowing the solder balls to be soldered without using flux.    
     
     
         14 . The method of  claim 13  further comprising including fluorine within the plasma products.  
     
     
         15 . The method of  claim 14  further comprising forming an oxyfluoride layer on the solder balls.  
     
     
         16 . The method of  claim 13  further comprising forming the solder balls at a solder ball forming station.  
     
     
         17 . The method of  claim 16  further comprising coating the solder balls at a coating station.  
     
     
         18 . The method of  claim 17  in which the coating station comprises a chamber containing the plasma products therein.  
     
     
         19 . The method of  claim 18  further comprising supplying the chamber with the plasma products from a plasma generator.  
     
     
         20 . The method of  claim 19  further comprising supplying the plasma generator with a gas containing fluorine.  
     
     
         21 . A method of forming fluxless solder forms comprising: 
 forming solder forms from a supply of solder; and    forming a layer on the solder forms for limiting naturally occurring oxide growth on the solder forms, the layer allowing the solder forms to be soldered without using flux.    
     
     
         22 . An apparatus for forming fluxless solder balls comprising: 
 a solder ball forming station for forming solder balls from a supply of solder; and    a coating station for forming a coating on the solder balls for limiting naturally occurring oxide growth on the solder balls before significant natural oxide growth on the solder balls has occurred, the coating allowing the solder balls to be soldered without using flux.    
     
     
         23 . The apparatus of  claim 22  in which the solder ball forming station forms the solder balls from molten solder.  
     
     
         24 . The apparatus of claims  23  in which the solder ball forming station forms falling droplets of molten solder which solidify while falling to form the solder balls.  
     
     
         25 . The apparatus of  claim 24  in which the coating station is positioned below the ball forming station for forming the coating on the solder balls while the solder balls are falling.  
     
     
         26 . The apparatus of  claim 25  in which the coating station treats the solder balls with plasma products.  
     
     
         27 . The apparatus of  claim 26  in which the plasma products include fluorine for forming an oxyfluoride layer on the solder balls.  
     
     
         28 . The apparatus of  claim 26  in which the coating station comprises a chamber containing the plasma products therein.  
     
     
         29 . The apparatus of  claim 28  further comprising a plasma generator for producing plasma and supplying the chamber with the plasma products.  
     
     
         30 . The apparatus of  claim 29  further comprising a gas source for supplying the plasma generator with a gas containing fluorine.  
     
     
         31 . An apparatus for forming fluxless solder balls comprising: 
 a solder ball forming station for forming falling droplets of molten solder which solidify while falling to form solder balls; and    a coating station positioned below the solder ball forming station for forming a coating on the solder balls by treating the solder balls with plasma products while the solder balls are falling and before significant natural oxide growth on the solder balls has occurred, the coating limiting naturally occurring oxide growth on the solder balls and allowing the solder balls to be soldered without using flux.    
     
     
         32 . The apparatus of  claim 31  in which the coating station treats the solder balls with plasma products.  
     
     
         33 . The apparatus of  claim 32  in which the plasma products include fluorine for forming an oxyfluoride layer on the solder balls.  
     
     
         34 . The apparatus of  claim 32  in which the coating station comprises a chamber containing the plasma products therein.  
     
     
         35 . The apparatus of  claim 34  further comprising a plasma generator for producing plasma and supplying the chamber with the plasma products.  
     
     
         36 . The apparatus of  claim 35  further comprising a gas source for supplying the plasma generator with a gas containing fluorine.  
     
     
         37 . A fluxless solder ball for a ball grid array comprising a generally round ball of solder, the ball of solder having a thin brittle oxyfluoride layer which limits naturally occurring oxide growth on the surface of the solder ball, during soldering, the oxyfluoride layer is capable of fracturing to allow the solder to flow, thereby permitting soldering without using flux.