Solder composition and method of bump formation therewith

Abstract

A solder composition capable of in the bump formation on a substrate, simplifying the coating operation. There is provided solder composition (10) comprising a mixture of liquid substance (12) and solder particles (11), wherein the liquid substance (12) contains a flux component of organic acid whose reaction temperature for oxide film removal is in the vicinity of the melting point of the solder particles and has such a viscosity that the liquid substance flows at ordinary temperature and accumulates in the form of a layer on substrate (20). The solder particles (11) consist of a particulate agent that settles in the liquid substance (12) toward a solder base material, having a particle diameter and mixing ratio enabling uniform dispersion in the liquid substance (12). By application of this solder composition onto substrate (20) with pad electrode (22) followed by heating, solder particles (11) adhere to the pad electrode (22) having its surface oxide film removed through reaction with the flux component to thereby promote soldering between any solder film formed on the base material and the solder particles (11), and further, aggregation of the solder particles (11) can be inhibited by a reaction product of the flux component to thereby form unbridged solder bumps (23).

Dependencies are inferred from the claim text.