Patent ID: 8796557

Claim:
An adhesive film, comprising: a first adhesive layer comprising conductive particles dispersed therein, a thermoplastic resin and a thermosetting resin; and a second adhesive layer adhered to the first adhesive layer, comprising a thermosetting resin and a thermoplastic resin, wherein the lowest viscosity of the first adhesive layer attained at or below a curing temperature thereof is higher than the lowest viscosity of the second adhesive layer attained at or below a curing temperature thereof, where the curing temperature is a temperature at which the adhesive layer starts to cure, wherein the first adhesive layer and the second adhesive layer are respectively disposed at a side of a substrate and a side of an electronic part, and the adhesive film is configured to join the electronic part and the substrate by heating and pressurizing the substrate and the electronic part with the adhesive film being therebetween, wherein the first adhesive layer has a thickness which is less than two times of an average particle diameter of the conductive particles, wherein the lowest viscosity of the second adhesive layer is 0.05 times to 0.2 times of the lowest viscosity of the first adhesive layer containing the conductive particles, and wherein the temperature at which the first adhesive layer has the lowest viscosity is the same temperature as the temperature at which the second adhesive layer has the lowest viscosity.