Solder ball excellent in micro-adhesion preventing properties and wetting properties and method for preventing the micro-adhesion of solder balls

Abstract

The present invention provides a solder ball that has solved the problem of micro-adhesion and, moreover, has solved both of the problems of micro-adhesion and wetting properties, and a method for preventing the micro-adhesion of solder balls. That is, the present invention provides a solder ball obtained by solidification and spheroidization in a gas phase and having metal soap molecules, preferably a metal soap molecules film of 3 nm or less in thickness, adsorbed on its surface. As the metal soap, there can be used, for example, calcium stearate, magnesium stearate or barium stearate. The present invention is preferably applied to solder balls with a diameter of 400 μm or less. The present invention also provides a method for preventing the micro-adhesion of solder balls which comprises immersing solder balls obtained by solidification and spheroidization in a gas phase, in a solution containing a metal soap dispersed therein, preferably, a solution containing a metal soap dispersed therein to a concentration of less than 5 ppm; taking out the solder balls from the solution; vaporizing the solvent on the surfaces of the solder balls; and then drying the surfaces. The drying is preferably conducted in an atmosphere having a relative humidity RH≦40%.

1 - 4 . (canceled)  
   
   
       5 . A method for preventing the micro-adhesion of solder balls which comprises immersing solder balls obtained by solidification and spheroidization in a gas phase, in a solution containing a metal soap dispersed therein, taking out the solder balls from the solution, vaporizing the solvent on the surfaces of the solder balls, and then drying the surfaces.  
   
   
       6 . A method for preventing the micro-adhesion of solder balls according to  claim 5 , wherein the solder balls obtained by solidification and spheroidization in a gas phase are immersed in a solution containing a metal soap dispersed therein to a concentration of less than 5 ppm.  
   
   
       7 . A method for preventing the micro-adhesion of solder balls according to  claim 5 , wherein the solvent on the surfaces of the solder balls is vaporized and then the surfaces are dried in an atmosphere having a relative humidity RH≦40%.  
   
   
       8 . A method for preventing the micro-adhesion of solder balls according to  claim 6 , wherein the solvent on the surfaces of the solder balls is vaporized and then the surfaces are dried in an atmosphere having a relative humidity RH≦40%.