Method of bonding with adhesive sheets for high-frequency dielectric heating

A bonding method of bonding together a first adherend and a second adherend made of a material different from a material forming the first adherend using a plurality of high-frequency dielectric heating adhesive sheets, wherein

• the plurality of high-frequency dielectric heating adhesive sheets include at least a first adhesive sheet and a second adhesive sheet,
• the first adhesive sheet contains a first thermoplastic resin,
• the second adhesive sheet contains a second thermoplastic resin,
• the first thermoplastic resin and the second thermoplastic resin are different resins,
• a volume content VA1 of the first thermoplastic resin with respect to a total volume of all thermoplastic resins in the first adhesive sheet is in a range from 60% by volume to 100% by volume,
• a volume content VA2 of the second thermoplastic resin with respect to a total volume of all thermoplastic resins in the second adhesive sheet is in a range from 60% by volume to 100% by volume,
• a change rate Vx1 represented by a numerical formula (Numerical Formula 1) below and indicating a rate of change between the volume content VA1 of the first thermoplastic resin and a volume content VB1 of the first thermoplastic resin with respect to a total volume of all thermoplastic resins in a sheet (1) disposed to be in direct contact with the first adhesive sheet is less than 80%,
• a change rate Vx2 represented by a numerical formula (Numerical Formula 2) below and indicating a rate of change between the volume content VA2 of the second thermoplastic resin and a volume content VB2 of the second thermoplastic resin with respect to a total volume of all thermoplastic resins in a sheet (2) disposed to be in direct contact with the second adhesive sheet is less than 80%,
• when an intermediate sheet is disposed between the first adhesive sheet and the second adhesive sheet, the sheet (2) disposed to be in direct contact with the second adhesive sheet is the intermediate sheet, and the sheet (1) disposed to be in direct contact with the first adhesive sheet is the intermediate sheet,
• when the first adhesive sheet and the second adhesive sheet are disposed to be in direct contact with each other, the sheet (2) disposed to be in direct contact with the second adhesive sheet is the first adhesive sheet, and the sheet (1) disposed to be in direct contact with the first adhesive sheet is the second adhesive sheet, and
• the bonding method comprises:
• disposing the first adhesive sheet and the second adhesive sheet between the first adherend and the second adherend such that the first adhesive sheet is in contact with the first adherend and the second adhesive sheet is in contact with the second adherend;
• and
• applying a high-frequency wave to the first adhesive sheet and the second adhesive sheet with the first adhesive sheet and the second adhesive sheet held between the first adherend and the second adherend to thereby bond the first adherend and the first adhesive sheet together and bond the second adherend and the second adhesive sheet together,
• Vx1={(VA1−VB1)/VA1}×100 (Numerical Formula 1)
• Vx2={(VA2-VB2)/VA2}×100 (Numerical Formula 2).