Method and apparatus for loading solder balls

Abstract

A solder ball loading apparatus for loading solder balls onto pads of a printed wiring board includes a holding device for holding a printed wiring board having pads and holding a ball array mask having openings that correspond to the pads, one or more cylinder members is positioned over the holding device such that an opening portion of the cylinder member faces the holding device, the cylinder member gathering solder balls on the surface of the ball array mask under the cylinder member by suctioning air through the opening portion. A conveyor mechanism for moving the ball array mask and the printed wiring board relative to the cylinder member such that solder balls gathered under the opening portion of the cylinder member can be loaded onto the pads of the board through the openings of the mask held by the holding device.

What is claimed: 
     
         1 . A solder ball loading apparatus for loading solder balls onto pads of a printed wiring board, comprising:
 a holding device configured to hold a printed wiring board having a plurality of pads and to hold a ball array mask having a plurality of openings that correspond to pads of the printed wiring board;   at least one cylinder member positioned over the holding device such that an opening portion of the cylinder member faces the holding device, the cylinder member being configured to gather solder balls on a surface of the ball array mask under the cylinder member by suctioning air through the opening portion of the cylinder member; and   a conveyor mechanism configured to move the ball array mask and the printed wiring board relative to the cylinder member such that solder balls gathered under the opening portion of the cylinder member can be loaded onto the pads of the printed wiring board through the openings of the ball array mask held by the holding device.   
     
     
         2 . The apparatus of  claim 1 , wherein the at least one cylinder member comprises a plurality of cylinder members arranged in proportion to a size of a printed wiring board held by the holding device. 
     
     
         3 . The apparatus of  claim 1 , further comprising a suction device configured to collect solder balls remaining on a ball array mask held by the mask fixing device. 
     
     
         4 . The apparatus of  claim 1 , wherein at least a section of the at least one cylinder member that comes in contact with the solder balls includes a conductive material. 
     
     
         5 . The apparatus of  claim 1 , wherein the cylinder member is configured to be positioned over a ball array mask held by the holding device with a clearance of 100-300% of a diameter of the solder balls. 
     
     
         6 . The apparatus of  claim 1  further comprising a ball array mask held by the holding device and having a plurality of openings that correspond to pads of a printed wiring board held by the holding device, wherein said openings of the ball array mask have a diameter of 1.1-1.5 times a diameter of the solder balls. 
     
     
         7 . The apparatus of  claim 1 , wherein the cylinder member has an opening size in the range of 1.2-3 times a diameter of pads on a printed wiring board held by the holding device. 
     
     
         8 . The apparatus of  claim 1 , wherein the conveyor mechanism is arranged to face a back side of the holding device that opposes a support surface of the holding device that holds the printed wiring board. 
     
     
         9 . The apparatus of  claim 8 , wherein the holding device comprises a mask clamp configured to clamp the ball array mask in a fixed position relative to the support surface such that the conveyor mechanism moves the ball array mask and support surface together. 
     
     
         10 . The apparatus of  claim 9 , wherein the loading cylinder is provided in a stationary position. 
     
     
         11 . A solder-ball loading apparatus for loading solder balls for solder bumps onto pads of a printed wiring board, comprising:
 means for holding a printed wiring board having a plurality of pads and holding a ball array mask having a plurality of openings that correspond to pads of the printed wiring board;   means for gathering solder balls above the ball array mask; and   means for moving the ball array mask and the printed wiring board such that at least some of the solder balls gathered above the ball array mask are loaded onto the pads of the printed wiring board through the openings of the ball array mask.