Electronic device

An electronic device comprising:

• a heat sink;
• and
• a semiconductor module provided on the heat sink,
• wherein the heat sink includes a first joined surface portion,
• wherein the semiconductor module includes
• a heat dissipation plate including a second joined surface portion joined to the first joined surface portion via a thermally-conductive bonding material, and
• a transistor chip placed on a side of the heat dissipation plate which is opposite to the second joined surface portion,
• wherein at least one joined surface portion out of the first joined surface portion and the second joined surface portion includes
• a plurality of protrusions protruding toward the other joined surface portion out of the first joined surface portion and the second joined surface portion,
• a first recess placed between the plurality of protrusions and recessed in a direction away from the other joined surface portion, and
• a second recess placed outward of the plurality of protrusions and recessed in the direction away from the other joined surface portion, and
• wherein a thickness at the first recess of the thermally-conductive bonding material is greater than a thickness of the thermally-conductive bonding material at the protrusions, and
• a thickness at the second recess of the thermally-conductive bonding material is greater than the thickness at the first recess.