Semiconductor device, semiconductor module, and system

A semiconductor device comprising:

• a composite board including a first member and a second member on a first surface that is one surface of the first member;
• at least one first conductor protrusion that protrudes from the second member in a direction in which the first surface faces;
• and
• a second conductor protrusion that protrudes from the composite board in the direction in which the first surface faces,
• wherein the first member includes a first semiconductor board,
• the second member includes a second semiconductor board having lower thermal conductivity than the first semiconductor board,
• a radio frequency amplifier circuit including a plurality of first transistors is in the second member,
• the first conductor protrusion is electrically connected to the plurality of first transistors and at least partially overlaps with the plurality of first transistors in a plan view of the first surface,
• the composite board includes a connection part that reaches the first semiconductor board or the second semiconductor board from the second conductor protrusion,
• in the plan view of the first surface, the connection part reaches the first semiconductor board or the second semiconductor board from the second conductor protrusion in a region in which the connection part at least partially overlaps with the second conductor protrusion, and is configured with a semiconductor material, a conductive material, or a laminate of a semiconductor material and a conductive material, and
• the second conductor protrusion is separated by greater than or equal to 55 μm from the first conductor protrusion in an in-plane direction of the first surface.