Semiconductor module

A power module includes: a base plate having a front surface provided with positioning wire bonding portions; an insulating substrate provided with hole portions accommodating the positioning wire bonding portions on a side of a back surface facing the base plate, and fixed to the base plate with being positioned with respect to the base plate by the hole portions accommodating the positioning wire bonding portions; and a semiconductor chip arranged on a side of a front surface of the insulating substrate opposite to the back surface.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor module.

2. Description of the Background Art

In a power semiconductor module, an insulating substrate, a semiconductor chip, and the like are mounted on a metal base plate by solder joint. For example, Japanese Patent Laying-Open No. 2000-031358 and Japanese Patent Laying-Open No. 01-281760 propose techniques of providing, in a semiconductor module in which an insulating substrate having a circuit layout formed using copper foil is mounted on a metal base plate, convex and concave portions at predetermined positions on the metal base plate for positioning of the insulating substrate.

In the semiconductor modules proposed in Japanese Patent Laying-Open No. 2000-031358 and Japanese Patent Laying-Open No. 01-281760, it is necessary to perform additional processing on the base plate to provide the convex and concave portions in the base plate, which increases man-hours and reduces manufacturing efficiency. Further, in a case where the convex and concave portions are provided using a mold or the like, it is also necessary to change the design of the mold itself when the locations for forming the convex and concave portions and the number of the convex and concave portions are changed, and thus it is difficult to use the mold for the production of a wide variety of products in small quantities.

SUMMARY OF THE INVENTION

The present invention has been made in view of the aforementioned problem, and one object of the present invention is to provide a semiconductor module in which a reduction in manufacturing efficiency is suppressed and an insulating substrate is positioned with respect to a base plate with a high degree of accuracy.

A semiconductor module in accordance with the present invention includes: a base plate having a front surface provided with a positioning wire bonding portion; an insulating substrate provided with a receiving portion accommodating the positioning wire bonding portion on a side of a back surface facing the base plate, and fixed to the base plate with being positioned with respect to the base plate by the receiving portion accommodating the positioning wire bonding portion; and a semiconductor chip arranged on a side of a front surface of the insulating substrate opposite to the back surface.

According to the semiconductor module in accordance with the present invention, a semiconductor module in which a reduction in manufacturing efficiency is suppressed and an insulating substrate is positioned with respect to a base plate with a high degree of accuracy can be provided.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings below, identical or corresponding parts will be designated by the same reference numerals, and the description thereof will not be repeated.

First, Embodiment 1 as one embodiment of the present invention will be described. To begin with, a structure of a semiconductor module in accordance with the present embodiment will be described. Referring toFIG. 1, a power module1as the semiconductor module in accordance with the present embodiment mainly includes a case2, a base plate3, a power terminal4, a signal terminal5, power wires4aand a signal wire5a(bonding wires), an insulating substrate8, a semiconductor chip10, a silicon gel12, and a sealing resin13.

Case2is arranged on a front surface3aof base plate3, and constitutes an internal space for accommodating semiconductor chip10, together with base plate3. Power terminal4is made of a metal, and extends while bending along an inner surface of case2to come close to semiconductor chip10. Power terminal4is connected to a patterned layer7formed on a front surface8aof insulating substrate8via power wire4a.

Signal terminal5is made of a metal, and extends along the inner surface of case2to come close to semiconductor chip10. Signal terminal5is arranged to face power terminal4and sandwich semiconductor chip10between itself and power terminal4in the internal space of case2. Signal terminal5is connected to semiconductor chip10via signal wire5a.

Insulating substrate8has front surface8aand a back surface8b, and patterned layers7,9are formed on front surface8aand back surface8b, respectively. Patterned layers7,9are made of, for example, copper foil or the like, and have a thickness of more than or equal to 0.1 mm and less than or equal to 0.5 mm Insulating substrate8is fixed to base plate3by a solder layer6, with being positioned with respect to base plate3. Solder layer6has a thickness of, for example, more than or equal to 0.1 mm and less than or equal to 0.5 mm. A mechanism for positioning insulating substrate8with respect to base plate3will be described later.

Semiconductor chip10is arranged on a side of front surface8aof insulating substrate8, and fixed to insulating substrate8by a solder layer11. Semiconductor chip10is a semiconductor device such as, for example, a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), an IGBT (Insulated Gate Bipolar Transistor), a diode, or the like. Although only one semiconductor chip10is fixed on insulating substrate8inFIG. 1, a plurality of the semiconductor devices described above may be placed next to each other and fixed on insulating substrate8.

Silicon gel12is charged into the internal space of case2and covers semiconductor chip10. Sealing resin13is arranged on silicon gel12. Thus, semiconductor chip10is sealed with silicon gel12and sealing resin13in the internal space of case2.

Next, the mechanism for positioning insulating substrate8with respect to base plate3will be described with reference toFIGS. 1 and 2.FIG. 2shows a state where base plate3and insulating substrate8are exploded in power module1(FIG. 1). Referring toFIG. 2, a plurality of positioning wire bonding portions20(20ato20d) are provided on front surface3aof base plate3. Positioning wire bonding portions20are fixed on base plate3by the same method as the method for fixing power wires4a, signal wire5a(FIG. 1), and like to semiconductor chip10and the terminals. More specifically, positioning wire bonding portions20are provided on front surface3aby applying heat, ultrasound, pressure, or the like to wires placed on front surface3aof base plate3.

Positioning wire bonding portions20are made of a metal as with power wires4aand signal wire5a, and are made of a metal material such as, for example, aluminum, copper, or the like. Positioning wire bonding portions20each have a diameter of, for example, more than or equal to 0.1 mm and less than or equal to 1.0 mm. Although positioning wire bonding portions20may be arranged at four corners of a quadrangle, respectively, as shown inFIG. 2, the number thereof and the method for arranging them are not particularly limited.

A plurality of hole portions21ato21d(receiving portions) for accommodating positioning wire bonding portions20ato20d, respectively, are provided in patterned layer9formed on back surface8b(surface facing base plate3) of insulating substrate8. More specifically, positioning wire bonding portions20ato20dcan be inserted into hole portions21ato21d, respectively, and thereby insulating substrate8is positioned with respect to base plate3.

Although hole portions21may be provided at corner portions (four corners) of a rectangle forming an outer peripheral shape of patterned layer9as shown inFIG. 2, positions of hole portions21are not limited thereto, and may be selected as appropriate depending on the number of positioning wire bonding portions20and the method for arranging them. For example, hole portions21may be provided at portions adjacent to the sides of the rectangle.

Power module1described above can be manufactured as described below. Referring toFIG. 1, first, insulating substrate8having patterned layers7,9formed thereon and semiconductor chip10are fixed on front surface3aof base plate3by soldering. Next, semiconductor chip10and patterned layer7are connected to power terminal4, signal terminal5, and the like, via power wires4aand signal wire5a. Subsequently, silicon gel12and sealing resin13are charged sequentially to seal semiconductor chip10. Thereby, power module1described above is obtained.

Next, the features of power module1in accordance with the present embodiment will be described, and the function and effect thereof will also be described. Power module1includes: base plate3having front surface3aprovided with positioning wire bonding portion20; insulating substrate8provided with hole portion21(receiving portion) accommodating positioning wire bonding portion20on a side of back surface8bfacing base plate3, and fixed to base plate3with being positioned with respect to base plate3by hole portion21accommodating positioning wire bonding portion20; and semiconductor chip10arranged on a side of front surface8aof insulating substrate8opposite to back surface8b.

In power module1described above, insulating substrate8can be fixed to base plate3with being positioned with respect to base plate3by positioning wire bonding portion20being accommodated in hole portion21. This further simplifies the steps and improves manufacturing efficiency when compared with a case where the base plate itself is processed to form convex and concave portions or the like, and the convex and concave portions are used for positioning of insulating substrate8. Further, positioning wire bonding portion20can be fabricated using the same facility as that used to connect power wires4aand signal wire5a, and the anchored position and the type of the wire can be easily changed for each kind. Furthermore, since formation of a resist for positioning of the insulating substrate on the base plate can be omitted, the base plate can be standardized.

In power module1described above, a plurality of positioning wire bonding portions20ato20dare provided on front surface3aof base plate3. In addition, a plurality of hole portions21ato21d(receiving portions) for accommodating the plurality of positioning wire bonding portions20ato20d, respectively, are provided on the side of back surface8bof insulating substrate8. Thereby, insulating substrate8can be positioned with respect to base plate3with a higher degree of accuracy.

In power module1described above, hole portion21(receiving portion) is provided in patterned layer9formed on back surface8bof insulating substrate8. Insulating substrate8is positioned with respect to base plate3by positioning wire bonding portion20being inserted into hole portion21. Thereby, insulating substrate8can be positioned with respect to base plate3with a further higher degree of accuracy.

First Variation

Next, a first variation of power module1in accordance with the present embodiment will be described.FIG. 3shows a structure of insulating substrate8and patterned layer9in the present variation. Referring toFIG. 3, in the present variation, a plurality of cutout portions22(22ato22d) (receiving portions) are formed at end portions of patterned layer9formed on back surface8bof insulating substrate8. More specifically, patterned layer9has an outer peripheral shape in the form of a rectangle, and cutout portions22ato22dare formed at four corner portions of the rectangle, respectively. Insulating substrate8is configured to be positioned with respect to base plate3by positioning wire bonding portions20ato20d(FIG. 2) being located at cutout portions22ato22d, respectively. Thereby, patterned layer9is processed more easily, and thus productivity can be more improved.

Second Variation

Next, a second variation of power module1in accordance with the present embodiment will be described.FIG. 4shows a structure of insulating substrate8and patterned layer9in the present variation. Referring toFIG. 4, in the present variation, cutout portions22a,22d, which are portions formed by cutting out two opposite corner portions of the rectangle forming the outer peripheral shape of patterned layer9, are formed. Insulating substrate8is configured to be positioned with respect to base plate3by positioning wire bonding portions20a,20d(FIG. 2) being located at cutout portions22a,22d, respectively. Thereby, the shape of patterned layer9is more simplified, and productivity is further improved. In addition, by forming cutout portions22a,22dat two opposite corner portions (two corner portions farthest from each other) of the rectangle, the accuracy of positioning insulating substrate8with respect to base plate3can be more improved.

Third Variation

Next, a third variation of power module1in accordance with the present embodiment will be described.FIG. 5shows a structure of insulating substrate8and patterned layer9in the present variation. Referring toFIG. 5, in the present variation, in addition to cutout portions22a,22dformed by cutting out two opposite corner portions of the rectangle forming the outer peripheral shape of patterned layer9, a cutout portion22c, which is a portion formed by cutting out one corner portion different from the two corner portions, is further formed. Insulating substrate8is configured to be positioned with respect to base plate3by positioning wire bonding portions20a,20c,20d(FIG. 2) being located at cutout portions22a,22c,22d, respectively. Thereby, insulating substrate8is suppressed from being inclined with respect to base plate3, and the accuracy of positioning insulating substrate8with respect to base plate3is further improved.

Fourth Variation

Next, a fourth variation of power module1in accordance with the present embodiment will be described.FIG. 6shows a structure of insulating substrate8and patterned layer9in the present variation. Referring toFIG. 6, in the present variation, cutout portions23ato23d, which are portions formed by cutting out the sides of the rectangle forming the outer peripheral shape of patterned layer9, are formed. Insulating substrate8is configured to be positioned with respect to base plate3by positioning wire bonding portions20being located at cutout portions23ato23d, respectively. Thereby, two or more bonding locations can be provided in each of positioning wire bonding portions20respectively located at cutout portions23ato23d. As a result, locations where the wire shape is not changed by bonding can be provided, and a distance corresponding to the wire diameter can be ensured more reliably between base plate3and insulating substrate8.

Next, Embodiment 2 as another embodiment of the present invention will be described. Basically, a semiconductor module in accordance with the present embodiment has the same configuration and exhibits the same effect as those of the semiconductor module in accordance with Embodiment 1. However, the semiconductor module in accordance with the present embodiment is different from the semiconductor module in accordance with Embodiment 1 in further including a control circuit for driving the semiconductor chip.

Referring toFIG. 7, a power module1A as the semiconductor module in accordance with the present embodiment further includes a control circuit composed of a relay terminal14, a printed substrate15, a plurality of SMT (Surface Mount Technology) components16, and an interface17, in addition to the configuration of power module1in accordance with Embodiment 1 (FIG. 1). This control circuit can drive semiconductor chip10.

Relay terminal14extends to come close to semiconductor chip10, and is connected to semiconductor chip10by a control wire14a. Printed substrate15is arranged on silicon gel12, and the plurality of SMT components16are arranged to be placed next to each other on a front surface of printed substrate15. Interface17has one end portion connected to printed substrate15, and the other end portion extending to the outside of case2. Thus, power module1A in accordance with the present embodiment is an intelligent power module (IPM) including the control circuit for driving semiconductor chip10.

The semiconductor module in accordance with the present invention is applicable particularly advantageously to a semiconductor module required to suppress a reduction in manufacturing efficiency and position an insulating substrate with respect to a base plate with a high degree of accuracy.

Although the embodiments of the present invention have been described, it should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the scope of the claims, and is intended to include any modifications within the scope and meaning equivalent to the scope of the claims.