Solder Paste

Abstract

To provide solder paste that can be filled in minute apertures. The solder paste that is printed on a substrate through a mask member in which apertures are formed is supplied to the apertures of the mask member under decompression pressure and has a viscosity so that the solder paste is filled in the apertures under atmospheric pressure. It is preferable that the solder paste has a viscosity of 50 through 150 Pa·s and a thixotropic ratio of 0.3 through 0.5. Further, the solder paste is obtained by mixing a flux containing solvent having a boiling point such that volatilization thereof is suppressed under the decompression pressure and solder powders. It is preferable that in the flux, the solvent having the boiling point of 240° C. or more is used and the solvent is octanediol.

1 . Solder paste that is printed on the substrate through a mask member in which aperture is formed and that is supplied to the aperture of the mask member under decompression pressure and has a viscosity so that it is filled in the aperture under atmospheric pressure. 
     
     
         2 . The solder paste according to  claim 1  characterized in that the solder paste has a viscosity of 50 through 150 Pa·s and a thixotropic ratio of 0.3 through 0.5. 
     
     
         3 . The solder paste according to  claim 2  characterized in that the solder paste is obtained by mixing a flux containing solvent having a boiling point such that volatilization thereof is suppressed under the decompression pressure and solder powders. 
     
     
         4 . The solder paste according to  claim 3  characterized in that in the flux, the solvent having the boiling point of 240° C. or more is used. 
     
     
         5 . The solder paste according to  claim 4  characterized in that as the solvent, octanediol is used.