| abstract |
The circuit board (1) includes an insulating substrate (2), a metal circuit board (3) bonded to one main surface of the insulating substrate (2), and a side opposite to one main surface of the insulating substrate (2). A heat sink (4) made of metal bonded to the main surface of the heat sink, and the thickness of the heat sink (4) is at least 3.75 times the thickness of the metal circuit board (3). The particle size of the metal particles contained in the metal circuit board (3) is smaller than the particle size of the metal particles contained in the metal circuit board (3), and the smaller the distance from the main surface on the opposite side of the insulating substrate (2), the smaller the particle size. ing. |