Low temperature solder column attach by injection molded solder and structure formed

A method for joining a multiplicity of multi-alloy solder columns to an electronic substrate comprising the steps of:

• providing a mold plate having a multiplicity of cavities,
• filling said multiplicity of cavities with a first solder having a melting temperature of at least 240° C. forming a multiplicity of solder columns,
• providing an extraction plate equipped with a multiplicity of displacement means positioned corresponding to the positions of said multiplicity of cavities in said mold plate when said extraction plate is positioned on top of said mold plate,
• providing a transfer plate equipped with a multiplicity of apertures for receiving solder columns, said multiplicity of apertures each having a straight opening and a flared opening,
• positioning said mold plate in between and in intimate contact with said extraction plate and said multiplicity of apertures in said transfer plate with said straight opening facing said mold plate,
• activating said multiplicity of displacement means in said extraction plate to displace said multiplicity of solder columns from said mold plate into said transfer plate,
• filling said flared openings of said multiplicity of apertures in said transfer plate with a second solder having a melting temperature of less than 240° C. encapsulating one end of each of said multiplicity of solder columns to form a flared end,
• positioning said transfer plate on top of an electronic substrate,
• heating said transfer plate and said electronic substrate to a temperature not lower than the melting temperature of said solder forming a bond between said multiplicity of solder columns and said multiplicity of conductive pads, and
• removing said transfer plate from said electronic substrate.