RELATED APPLICATIONS

The present application is based on, and claims priority from, Japanese Application No. 2020-107882 filed Jun. 23, 2020, the disclosure of which is hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to semiconductor modules and methods for manufacturing the same, particularly power semiconductor modules and methods for manufacturing the same.

2. Description of the Related Art

Power semiconductor modules are widely applied in the fields of requiring efficient power conversion. Examples of the fields include those for renewable energy such as solar power generation and wind power generation, which have been attracting attention recently, for vehicles such as hybrid vehicles and electric vehicles, and for railway such as railway vehicles.

Such a power semiconductor module includes a switching device and a diode built therein. For the power semiconductor device, a wide bandgap semiconductor such as a Si (silicon) semiconductor or a SiC (silicon carbide) semiconductor has been used. SiC semiconductor has features of high withstanding voltage, high heat resistance, and low loss as compared with Si semiconductor. A power semiconductor module made of SiC semiconductor therefore enables a compact apparatus and reduces the loss. To produce the apparatus, the power semiconductor device is sealed with a sealing material including epoxy resin, which has excellent moisture resistance, heat resistance, and mechanical properties. This allows the apparatus to have excellent insulating property and keep a shape, and so a caseless and/or baseless structured apparatus can be produced.

To increase the rated current for large capacity, the module has to upsize. In this case, a caseless/baseless structure has several problems, including the stress due to a sealing material and deterioration of the insulation property due to an unfilled inside part (e.g., void) with resin, and this makes it difficult to increase the capacity of the structure.

To achieve large capacity, another way may include producing units each having a small module size to reduce the current capacity per module, and then connecting these units with a busbar. An increase in withstand voltage of the power semiconductor module, however, requires a long insulation distance, which makes it difficult to downsize the entire module.

To solve the above problems, a technique is proposed, which places a semiconductor unit sealed with a sealing material on a base, forms a recess on the upper face of the semiconductor unit, bonds the external terminal pin of the unit to the external terminal busbar, and embeds the joint or bonded portion with resin (Patent Document 1). The document proposes example methods of the bonding, including solder bonding and laser welding. This technique has problems for bonding in the recess, including the difficulties in inserting a soldering iron into the recess or in letting laser light in the recess.

[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2014-49582

SUMMARY OF THE INVENTION

In view of the above problems, the present invention provides a semiconductor module configured for easy connection of extraction pins with a wiring board and having reliable connections, and a method for manufacturing the same.

A semiconductor module according to one aspect of the present invention includes: a multilayer board having a semiconductor device thereon, the multilayer board electrically connecting to the semiconductor device; an extraction pin electrically connecting to one of the semiconductor device and the multilayer board; and a wiring board bonded to the extraction pin for electrical connection.

The extraction pin has a press-fit. The wiring board has a hole portion bonded with the press-fit of the extraction pin. The base materials of the press-fit of the extraction pin and the hole portion of the wiring board are copper (Cu). A bonded portion between the base materials of the press-fit and the hole portion of the wiring board includes a CuSnNi alloy layer.

A method for manufacturing according to another aspect of the present invention includes: mounting a semiconductor device on a multilayer board; vertically disposing an extraction pin which electrically connects to one of the semiconductor device and the multilayer board; and bonding a wiring board to the extraction pins for electrical connection.

The extraction pin has a press-fit. The wiring board has a hole portion bonded with the press-fit of the extraction pin. The base materials of the press-fit of the extraction pin and the hole portion of the wiring board are copper (Cu). A bonded portion between the base materials of each press-fit and the corresponding hole portion of the wiring board includes a CuSnNi alloy layer.

A power semiconductor module according to the present invention enables easy connection of an extraction pin with a wiring board, and has reliable a connection, and the present invention also provides a method for manufacturing the same.

