Conductive adhesive, and circuit board and electronic component module using the same

1. A conductive adhesive comprising:

82 wt % of Sn—Bi system solder powder and;

18 wt % of an adhesive containing organic acid, wherein

the Sn—Bi system solder powder is composed of solder particles having a particle size L 1 of 20 to 30 μm and solder particles having a particle size L 2 of 8 to 12 μm,

the particle size L 1 is represented by a median diameter (D50) which is a particle size where an integrated particle amount is 50%,

the particle size L 2 is represented by a median diameter (D50) which is a particle size where an integrated particle amount is 50%,

a mixing ratio of the Sn—Bi system solder powder is such that the solder particles having the particle size L 1 of 20 to 30 μm occupy 70 wt % with respect to the whole solder powder, and 30 wt % is occupied by solder particles having the particle size L 2 of 8 to 12 μm,

a solder composition of the Sn—Bi system solder powder is 42 wt % Sn-58 wt % Bi, and

the adhesive containing organic acid is made up of 16 wt % of bisphenol A type epoxy resin, 62 wt % of bisphenol F type epoxy resin, 12 wt % of imidazole system curing agent, 3.0 wt % of adipic acid, 6.0 wt % of glutaric acid, and 1.0 wt % of thicking agent.

2. A circuit board comprising:

a base plate; and

a conductive part formed on the base plate comprising the conductive adhesive according to claim 1 .

3. An electronic component module comprising:

a circuit board;

a conductive part formed on the circuit board comprising the conductive adhesive according to claim 1 ; and

an electronic component mounted on the circuit board via the conductive part.