Power module and power conversion device

1. A power module, comprising:

a semiconductor element for converting DC current to AC current by switching operation;

an electrical wiring board to which the semiconductor element is electrically connected, with the semiconductor element being disposed upon one of principle surfaces of the electrical wiring board;

an insulating resin layer provided on another principal surface of the electrical wiring board;

a first alumite layer that is formed by first alumite processing and is disposed on an opposite side of the electrical wiring board from the semiconductor element, separated by the insulating resin layer, and that is joined to the insulating resin layer;

a second alumite layer that is formed by second alumite processing and is disposed on an opposite side of the insulating resin layer from the semiconductor element, separated by the first alumite layer, and that ensures electrical insulation of the semiconductor element; and

a metallic heat dissipation member that is disposed on an opposite side of the second alumite layer from the first alumite layer, separated by the second alumite layer, and that radiates heat generated by the semiconductor element via the electrical wiring board, the insulating resin layer, the first alumite layer, and the second alumite layer;

wherein a hole diameter of the first alumite layer is greater than a hole diameter of the second alumite layer; and

wherein a thickness of the second alumite layer is greater than a thickness of the first alumite layer.

2. A power module according to claim 1 wherein:

the metallic heat dissipation member is made from an aluminum alloy;

the first alumite layer is formed upon the metallic heat dissipation member by performing the first alumite processing of an inorganic acid type upon the metallic heat dissipation member; and

the second alumite layer is formed upon the metallic heat dissipation member by performing the second alumite processing of an organic acid type upon the metallic heat dissipation member.

3. A power module according to claim 2 , wherein the second alumite processing of the organic acid type that is performed for the second alumite layer is alumite processing with oxalic acid.

4. A power module according to claim 1 , wherein the electrical wiring board is made from a Cu alloy, and, on the one of the principal surfaces of the electrical wiring board that faces the insulating resin layer, is subjected to oxidization processing such as roughening processing or blackening processing.

5. A power module, comprising:

a semiconductor element for converting DC current to AC current by switching operation;

a first electrical wiring board, arranged so as to oppose a first electrode that is on one side of the semiconductor element, and electrically connected to the semiconductor element;

a second electrical wiring board, arranged so as to oppose a second electrode that is on another side of the semiconductor element, and electrically connected to the semiconductor element;

insulating resin layers disposed on both sides of the semiconductor element, with the first and second electrical wiring boards being arranged between the semiconductor element and a respective insulating resin layer;

a first alumite layer formed by first alumite processing for adhering to the insulating resin layer, separated by the insulating resin layer;

a second alumite layer for ensuring electrical insulation of the semiconductor element, separated by the first alumite layer; and

metallic heat dissipation members for radiating heat generated by the semiconductor element, disposed on both sides of the semiconductor element, each separated by the first electrical wiring board or the second electrical wiring board, the insulating resin layer, the first alumite layer, and the second alumite layer;

wherein a hole diameter of the first alumite layer is greater than a hole diameter of the second alumite layer; and

wherein a thickness of the second alumite layer is greater than a thickness of the first alumite layer.

6. A power module according to claim 5 , wherein:

the metallic heat dissipation member is made from an aluminum alloy;

the first alumite layer is formed upon the metallic heat dissipation member by performing the first alumite processing of an inorganic acid type upon the metallic heat dissipation member; and

the second alumite layer is formed upon the metallic heat dissipation member by performing a second alumite processing of an organic acid type upon the metallic heat dissipation member.

7. A power module according to claim 5 , wherein the first electrical wiring board and the second electrical wiring board are made from a Cu alloy, and, on a principal surface of each of the first electrical wiring board and the second electrical wiring board that face the insulating resin layers, are subjected to oxidization processing such as roughening processing or blackening processing.

8. A power module, comprising:

a semiconductor element for converting DC current to AC current by switching operation;

a first electrical wiring board, arranged so as to oppose a first electrode that is on one side of the semiconductor element, and electrically connected to the semiconductor element;

a second electrical wiring board, arranged so as to oppose a second electrode that is on another side of the semiconductor element, and electrically connected to the semiconductor element;

a sealing resin mass that seals the semiconductor element, the first electrical wiring board, and the second electrical wiring board, so that portions of surfaces of the first electrical wiring board and the second electrical wiring board that do not face the semiconductor element are exposed;

a metallic casing having an aperture for insertion of the semiconductor element, the first electrical wiring board, and the second electrical wiring board, that is sealed by the sealing resin mass; and

an insulation sheet that is inserted between an exposed surface of the first electrical wiring board and the second electrical wiring board, and an inner wall of the metallic casing;

wherein, upon the metallic casing, a first alumite layer for adhering to the insulation sheet is formed upon a surface of the metallic casing that faces the insulation sheet and the metallic casing, and a second alumite layer is formed opposite from the insulation sheet, separated by the first alumite layer;

wherein a hole diameter of the first alumite layer is greater than a hole diameter of the second alumite layer; and

wherein a thickness of the second alumite layer is greater than a thickness of the first alumite layer.

9. A power module according to claim 8 , wherein:

the metallic casing is made from an aluminum alloy;

the first alumite layer is formed upon the metallic casing by performing first alumite processing of an inorganic acid type upon the metallic casing; and

the second alumite layer is formed upon the metallic casing by performing second alumite processing of an organic acid type upon the metallic casing.

10. A power module according to claim 8 , wherein the first electrical wiring board and the second electrical wiring board are made from a Cu alloy, and, on a principal surface of each of the first electrical wiring board and the second electrical wiring board that face the insulation sheet, are subjected to oxidization processing such as roughening processing or blackening processing.