Method for production of semiconductor package

Abstract

The invention provides a method for producing semiconductor packages comprising the steps of forming electronic circuits for a plurality of semiconductor chips 11 on a wafer 1, forming bumps 2 on the plurality of semiconductor chips 11, encapsulating the circuit-forming surface 111 of the wafer 1 and the bumps 2 with a sealant by screen printing means to form a sealant layer 4, curing the sealant layer 4, grinding the surface of the sealant layer 4 until the upper end surface of the bump 2 becomes exposed, placing solder balls on said upper end surface of bumps 2 to weld the balls to the surface thereof, and dicing the wafer 1 and the sealant layer 4 as united into individual semiconductor chips 11. Screen printing means is used to encapsulate the entire surface of the wafer with a resin, so that the equipment costs can be markedly reduced as compared with conventional methods using a mold.

1. A method for producing semiconductor packages,  comprising the steps of :
 forming electronic circuits for a plurality of semiconductor chips on a surface of a semiconductor wafer;  
 forming substantially columnar shaped bumps on circuit-provided  the surface of the semiconductor wafer in accordance with the electronic circuits  by a plating method, each bump having an upper end and a height;  
 screen-printing the bump-provided  surface of the semiconductor wafer with a resin sealant to encapsulate the bumps, including their  the upper ends of the bumps, and the remaining circuit-provided  electronic circuits formed on the surface of the semiconductor wafer with the resin sealant, by placing a metal mask having a single through- hole and a thickness which is larger than the height of each bump over the surface of the semiconductor wafer,  thereby forming a sealant layer;  
 curing the sealant layer;  
 grinding the cured sealant layer downward until the upper ends of the bumps become exposed; and  
 placing solder balls on the exposed upper ends of the bumps to weld the balls thereto; and 
 dicing the semiconductor wafer and the sealant layer as an integrated unit into individual semiconductor chips.  
 
     
     
       2. The method according to  claim 1 , wherein the screen-printing step  comprises the steps of :
 placing a mask having through-holes on the bump-provided surface of the wafer; 
 feeding the resin sealant onto the placed mask; and  
 squeegeeing the resin sealant onto the bump-provided  surface of the semiconductor wafer through the through-holes  single through- hole of the mask  by sliding a squeegee along the mask with a reciprocative movement.  
 
     
     
       3. The method according to  claim 2 , wherein the squeegee is made of elastic material and is passed over the bumps to make  in a manner so as to cause the resin sealant to cave in between the bumps while being slid along the mask. 
     
     
       4. The method according to  claim 1 , wherein the resin sealant is a viscous fluid. 
     
     
       5. The method according to  claim 1 , further comprising welding solder balls to the bumps. 
     
     
       6. The method according to  claim 5 , wherein the welding comprises placing the solder balls on the exposed upper ends of the bumps. 
     
     
       7. The method according to  claim 1 , wherein the screen- printing is performed under a vacuum atmosphere.   
     
     
       8. The method according to  claim 1 , wherein the bumps have a substantially same width at a lower end as at the upper end, and a same specified height. 
     
     
       9. The method according to  claim 1 , wherein the single through- hole has a size which is not larger than the size of the wafer.   
     
     
       10. The method according to  claim 9 , wherein the single through- hole has a diameter which is smaller by about  1  mm to about  10  mm than a diameter of the semiconductor wafer.   
     
     
       11. The method according to  claim 1 , wherein the resin sealant includes silica. 
     
     
       12. The method according to  claim 1 , wherein the sealant layer is thinned to a minimum thickness of about  50  μm. 
     
     
       13. The method according to  claim 1 , wherein the cured sealant layer is ground to a thickness of no less than  50  μm. 
     
     
       14. The method according to  claim 1 , wherein the resin sealant is screen printed on the entire circuit- forming surface of the semiconductor wafer.   
     
     
       15. The method according to  claim 1 , wherein the semiconductor wafer comprises a periphery, and the metal mask is placed on the periphery of the semiconductor wafer. 
     
     
       16. The method according to  claim 1 , wherein the sealant layer is formed on the entire circuit- forming surface of the wafer.   
     
     
       17. The method according to  claim 15 , wherein the resin sealant includes silica. 
     
     
       18. The method according to  claim 17 , wherein the forming of the sealant layer comprises squeegeeing the resin sealant onto the surface of the semiconductor wafer through the single through- hole of the mask by sliding a squeegee along the mask with a reciprocative movement.   
     
     
       19. A method comprising:
   forming electronic circuits for a plurality of semiconductor chips on a surface of a semiconductor wafer;        forming substantially columnar shaped bumps on the surface of the semiconductor wafer by a plating method, each bump having an upper end and a height;        screen - printing the surface of the semiconductor wafer with a resin sealant including silica in an amount of  60 - 95   %  of the resin sealant by weight to encapsulate the bumps, including the upper ends of the bumps, and the electronic circuits formed on the surface of the semiconductor wafer with the resin sealant, thereby forming a sealant layer;        curing the sealant layer;        grinding the cured sealant layer downward until the upper ends of the bumps become exposed; and        dicing the semiconductor wafer and the sealant layer as an integrated unit into individual semiconductor chips.     
     
     
       20. The method according to  claim 19 , wherein the screen- printing comprises squeegeeing the resin sealant onto the surface of the semiconductor wafer by sliding a squeegee along a metal mask having a single through - hole.