Patent ID: 8613623

Claim:
An acrylic insulating adhesive for fixing an electronic part to a circuit board, comprising a (meth)acrylate monomer, a film-forming resin, an inorganic filler, a silane coupling agent, a stress relaxing agent in an amount of 1 to 10 parts by mass with respect to the total of 100 parts by mass of the (meth)acrylate monomer and the film-forming resin, and a radical polymerization initiator, wherein an amount of the inorganic filler is 70 to 160 parts by mass with respect to a total of 100 parts by mass of the (meth)acrylate monomer and the film-forming resin, the stress relaxing agent includes at least one of nitrile butadiene rubber (NBR) and butadiene rubber (PB), a radical polymerization cured product of the acrylic insulating adhesive exhibits a glass transition temperature of 150 to 185° C., a linear expansion coefficient (a1) of 30 to 35 ppm in a temperature range that is lower than the glass transition temperature, and a linear expansion coefficient (a2) of 105 to 125 ppm in a temperature range that is equal to or higher than the glass transition temperature, and the following expression (1) is satisfied: a 2 /a 1 3 ≧3.4 (1).