Resin composition for solder bump formation, solder bump formation method, and member having solder bumps

A solder bump formation method which comprises:

• using a solder bump formation resin composition containing (A) an alkali-soluble thermoplastic resin which is a solid at ambient temperature, (B) a solvent, and (C) a solder powder, the solder bump formation resin composition containing no activating agent,
• the component (A) being at least one species selected from among the group consisting of i) an unsaturated fatty acid polymer having an acid value of 80 to 110 mgKOH/g, ii) a monobasic unsaturated fatty acid-aromatic unsaturated compound copolymer having an acid value of 110 to 220 mgKOH/g, iii) a dibasic unsaturated fatty acid-aromatic unsaturated compound copolymer having an acid value of 200 to 215 mgKOH/g, and iv) a rosin-modified resin having an acid value of 140 to 220 mgKOH/g,
• the rosin-modified resin being at least one species selected from the group consisting of i) a rosin-modified resin prepared through adding a dibasic unsaturated fatty acid to rosin, adding a polyhydric alcohol thereto, and carrying out esterification at high temperature, ii) a rosin-modified phenolic resin, and iii) a rosin POE ester product;
• placing a resist layer provided with an opening on a member having a pad such that the pad is exposed to the opening;
• filling the opening with the solder bump formation resin composition;
• removing the component (B);
• melting the component (C) by heating;
• and
• removing the resist layer and the component (A).