| 摘要 |
PROBLEM TO BE SOLVED: To prevent short circuit while enhancing heat dissipation by providing an anode oxide film on the surface of heat sink. SOLUTION: An anode oxide film 3 is formed on the surface of an aluminum heat sink 1. The anode oxide film 3 is formed at a thickness of 5-15μm by subjecting the aluminum heat sink 1 to anode oxidation through sulfuric acid bath or oxalic acid bath. The anode oxide film 3 is composed of alumina and exhibits high electric insulation. Alumina can be formed at low cost by anode oxidation and an oxide film can be formed easily and uniformly even at a part of intricate shape, e.g. a hole. The aluminum heat sink 1 is bonded to the rear surface of a metal substrate 5. Since the metal substrate 5 can be utilized as a power supply path of a heating element 9, power supply line can be eliminated and since alumina excellent in thermal conductivity is employed as an insulation film, a thermal head excellent in heat dissipation properties can be obtained.
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