| 摘要 |
PROBLEM TO BE SOLVED: To enhance heat dissipation by making a hole of an arbitrary size in the surface of a substrate tightly touching the surface of a heat sink built in a mold frame thereby enlarging the contact surface between the heat sink and a premix. SOLUTION: In a brushless DC motor incorporating a circuit, a mold frame is formed by molding a stator and a substrate 4 through premix. A power IC 9 is mounted on the substrate 4 and fixed tightly with a heat sink 10. A hole 4a is made through the substrate 4 and and the heat sink 10 is fixed to close the hole 4a. Size of the hole 4a is determined to fix the heat sink 10 to the substrate 4 with such a strength as the heat sink 10 is not stripped off from the substrate 4 by the molding pressure. Since the contact surface between the heat sink and the premix is enlarged, heat dissipation of the heat sink 10 can be enhanced. |
