Power semiconductor module

Abstract

To provide a power semiconductor module which facilitates simultaneous insertion of terminals of a power semiconductor element group into through-holes of a circuit board.SOLUTION: A power semiconductor module of the present invention includes a plurality of power semiconductor elements 1 fixed to a mounting member 2, an electronic component that drives the power semiconductor elements 1, and a rigid circuit board 3, in which the rigid circuit board 3 has a plurality of through windows provided at positions corresponding to the plurality of power semiconductor elements 1, and terminals 11 of the power semiconductor elements 1 are bonded to rigid portions 32 disposed in the plurality of through windows, respectively. A terminal of the electronic component is joined to the rigid circuit board 3, the rigid part 32 and the rigid circuit board 3 are joined by a flexible part having flexibility, and the power semiconductor element 1 and the electronic component are electrically connected.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power semiconductor module, and more particularly to a power semiconductor module in which terminals can be easily inserted into through holes. [Background technology]

[0002] Power semiconductor modules using switching elements such as power MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors) and IGBTs (Insulated Gate Bipolar Transistors), and semiconductor elements such as freewheel diodes are used for power control and motor control in electric vehicles, industrial equipment, and other devices.

[0003] In recent years, as there has been a demand for miniaturization of power semiconductor modules, in order to make layout easier, power semiconductor modules are sometimes used that combine multiple discrete power semiconductor elements, each of which is a single chip, and then fixed to a mounting member to form a module, rather than an integrated module in which multiple elements are housed in a single package.

[0004] In such a modularized structure in which multiple power semiconductor elements are fixed to a mounting member, the positional accuracy of the power semiconductor elements relative to the mounting member is likely to decrease, making it difficult to simultaneously insert the terminal groups of the multiple power semiconductor elements, which are fixed to the mounting member and modularized, into the through holes of the circuit board.

[0005] Although not related to a power semiconductor module, Patent Document 1 discloses a circuit board in which a vibration absorbing piece is formed by a slit provided in the circuit board, and a through hole is provided in this vibration absorbing piece. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-152286 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the vibration absorbing piece described in Patent Document 1 swings up and down relative to the surface of the circuit board, and does not absorb the decrease in positional accuracy of the power semiconductor element to facilitate terminal insertion.

[0008] The present invention has been made in consideration of the problems associated with the conventional technology, and an object of the present invention is to provide a power semiconductor module that can absorb misalignment of the terminals even when the precision of the terminal positions of the power semiconductor elements fixed to the mounting member is low, and that makes it easy to simultaneously insert the terminals of the power semiconductor elements into the through holes of the circuit board. [Means for solving the problem]

[0009] As a result of extensive research into achieving the above-mentioned object, the inventors discovered that by joining a power semiconductor element to a rigid portion joined to a rigid circuit board with a flexible portion, the rigid portion can be shifted relative to the rigid circuit board, making it easier to insert the terminals of the power semiconductor element into the through holes in the rigid portion, thereby achieving the above-mentioned object, and thus completed the present invention.

[0010] That is, the power semiconductor module of the present invention comprises a plurality of power semiconductor elements fixed to a mounting member, electronic components for driving the power semiconductor elements, and a rigid circuit board. The rigid circuit board has a plurality of through windows provided at positions corresponding to the plurality of power semiconductor elements, terminals of the power semiconductor elements are joined to rigid portions respectively arranged in the plurality of through windows, terminals of the electronic components are joined to the rigid circuit board, and the rigid portions and the rigid circuit board are joined by flexible portions having flexibility, thereby electrically connecting the power semiconductor elements and the electronic components. [Effects of the Invention]

[0011] According to the present invention, a power semiconductor element is joined to a rigid portion which is joined to a rigid circuit board via a flexible portion having flexibility, and therefore, a power semiconductor module can be provided in which the terminals of the power semiconductor element fixed to the mounting member can be easily inserted into the through holes even if the terminals are misaligned. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view showing a configuration of a power semiconductor module according to the present invention; [Figure 2] FIG. [Figure 3] FIG. 4 is a cross-sectional view showing the structure of a flexible portion. [Figure 4] 10 is an enlarged view showing a flexible portion provided in a direction perpendicular to the side of the through window. FIG. [Figure 5] 10 is an enlarged view showing a flexible portion provided obliquely to a side of the through window. FIG. [Figure 6] FIG. 10 is an enlarged view showing an example of a flexible section that is bent multiple times in different directions. [Figure 7] 10 is an enlarged view showing a state in which the direction in which the variation in the terminals of the power semiconductor element increases and the direction in which the amount of deviation of the rigid portion increases are aligned. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] The power semiconductor module of the present invention will now be described in detail. As shown in FIG. 1, the power semiconductor module of the present invention includes a plurality of power semiconductor elements 1, electronic components (not shown) that drive the power semiconductor elements, and a rigid circuit board 3.

[0014] The power semiconductor element is a discrete power semiconductor element consisting of one chip, and a plurality of such discrete power semiconductor elements are fixed together to a mounting member 2 to form a module.

[0015] The rigid circuit board 3 is a hard printed circuit board in which a circuit is formed on a substrate made of glass or paper impregnated with epoxy resin or the like.

[0016] As shown in FIG. 2, the rigid circuit board of the present invention has through windows 31 penetrating through the rigid circuit board in the thickness direction, and these through windows 31 are formed in the same number as the number of power semiconductor elements fixed to the mounting member, and are each located at a position corresponding to the power semiconductor elements.

[0017] A rigid portion 32 formed from the same base material as the rigid circuit board is disposed inside each of the through windows 31, and a gap 33 is defined between the through window 31 and the rigid portion 32.

[0018] In the power semiconductor module of the present invention, the terminals 11 of each power semiconductor element fixed to the mounting member 2 are joined to the rigid portions 32 arranged at the corresponding locations, and the terminals of the electronic components are joined to the rigid circuit board 3.

[0019] The rigid portion 32 is joined to the rigid circuit board 3 via the flexible portion 34, so that the power semiconductor element of the rigid portion and the electronic components of the rigid circuit board are electrically connected by the flexible portion 34.

[0020] As shown in Figure 3, this flexible part 34 has a laminated structure in which copper foil 4 is covered with a coverlay 5 made of polyimide or the like and these are bonded together with an adhesive, and since it is flexible, the rigid part can shift in the in-plane direction of the rigid circuit board due to twisting or bending of the flexible part.

[0021] Therefore, even if the positional accuracy of each power semiconductor element 1 fixed to the mounting member 2 is low and a power semiconductor element is shifted from its predetermined position, the rigid portion 32 at the location corresponding to the position of the power semiconductor element shifts in the in-plane direction of the rigid circuit board to absorb the positional shift of the power semiconductor element, and therefore the terminal 11 can be easily inserted into the through hole 321 of the rigid portion 32.

[0022] The mounting member also serves as a cooler for cooling the power semiconductor elements, and is fixed to a housing having a coolant flow path, and the rigid circuit board is also fixed to the housing.

[0023] In this way, when vibration is input while both the mounting member and the rigid circuit board are fixed to the housing, stress is applied to the terminals of the power semiconductor element, reducing the reliability of the solder joint between terminal 11 and through hole 321.

[0024] In the power semiconductor module of the present invention, the flexible portion can absorb vibrations and prevent stress from concentrating on the terminals, thereby improving the reliability of the solder joints.

[0025] The flexible portion 34 can be formed by grinding only the base material 6 portion of the rigid circuit board, leaving the circuit portion printed on the rigid circuit board, as shown in Figure 3. By grinding only the base material portion that forms the gap 33 between the through window 31 and the rigid portion 32 of the rigid circuit board, the rigid portion 32 joined to the rigid circuit board 3 via the flexible portion 34 can be positioned within the through window.

[0026] The flexible portion 34 thus formed may be arranged perpendicular to the side of the through window 31 as shown in Figure 4, but it is preferable that it is arranged diagonally to the side of the through window as shown in Figure 5, connecting the rigid portion and the rigid circuit board diagonally.

[0027] As shown in Figure 4, when the flexible part 34 is arranged in a direction perpendicular to the side of the through window 31 to connect the rigid part 32 and the rigid circuit board 3, its length becomes the same as the width of the gap 33 between the through window and the rigid part, and the flexible part becomes taut, reducing the amount of misalignment of the rigid part 32.

[0028] By providing the flexible portion 34 at an angle to the side of the through window 31, the amount of deviation of the rigid portion increases, so that it is possible to prevent stress from being continuously applied to the flexible portion due to deviation of the rigid portion caused by deviation of the terminal position.

[0029] In the present invention, "connecting the rigid portion and the rigid circuit board diagonally" means that it is sufficient that the line connecting the two connection portions, the connection portion between the flexible portion and the rigid portion and the connection portion between the flexible portion and the rigid circuit board, is diagonal with respect to the side of the through window. As shown in FIG. 5, the two connection portions may be connected in a straight line, or as shown in FIG. 6, the shape may be an S-shape, a crank shape, a zigzag shape, or another shape that is bent multiple times in different directions in the plane of the rigid circuit board.

[0030] The flexible portions 34 may be provided on all sides of the through window 31, but by providing the flexible portions 34 only on two parallel sides of the through window 31, the amount of displacement of the rigid portions 32 can be made anisotropic.

[0031] As described above, by making the amount of deviation of the rigid portion 32 anisotropic and aligning the direction in which the positional variation of the terminal 11 of the power semiconductor element is likely to be large with the direction in which the amount of deviation of the rigid portion 32 is large, it is possible to make it easier to insert the terminal into the through hole of the rigid portion.

[0032] For example, the terminals 11 of power semiconductor elements often have a rectangular cross section, and terminals of this shape tend to bend in the direction of the short side of the cross section, with greater variation in the short side direction than in the long side direction.

[0033] Therefore, by providing flexible portions 34 only on the two parallel sides of the through window 31 on both sides of the long side of the cross section of the terminal 11 so that the direction in which the rigid portion is most misaligned, as indicated by the arrow in Figure 7, is the same as the short side direction of the cross section of the terminal 11, it is possible to facilitate insertion of the terminal 11 into the through hole 321 of the rigid portion 32. That is, in the horizontal direction in FIG. 7, tension is applied to the flexible portion 34, suppressing variations, and in the vertical direction in FIG. 7, the gap between the terminal 11 and the through hole 321 is reduced, suppressing variations.

[0034] The number of flexible parts to be provided on the two parallel sides and their locations can be determined appropriately depending on the number and shape of the terminals to be inserted, but by providing multiple flexible parts on each of the two parallel sides, it is possible to prevent the rigid parts from shifting significantly out of the plane of the rigid circuit board, and to prevent excessive stress from being applied to the flexible parts. [Explanation of symbols]

[0035] 1. Power semiconductor element 11 terminals 2 Mounting materials 3 Rigid circuit board 31 Through window 32 Rigid part 321 through hole 33 Gap 34 Flexible section 4 Coverlay 5 Copper foil 6 Base material

Claims

1. a plurality of power semiconductor elements fixed to a mounting member; an electronic component that drives the power semiconductor element; A power semiconductor module comprising: the rigid circuit board has a plurality of through-windows provided at positions corresponding to the plurality of power semiconductor elements, terminals of the power semiconductor elements are joined to rigid portions respectively arranged in the plurality of through windows, and terminals of the electronic components are joined to the rigid circuit board, A power semiconductor module characterized in that the rigid portion and the rigid circuit board are joined by a flexible portion having flexibility, and the power semiconductor element and the electronic component are electrically connected.

2. 2. The power semiconductor module according to claim 1, wherein the flexible portion is bent a plurality of times in different directions within the plane of the rigid circuit board.

3. The terminal of the power semiconductor element has a rectangular cross-sectional shape, The through window has at least two parallel sides, 2. The power semiconductor module according to claim 1, wherein the flexible portions are provided on two parallel sides on both sides in the direction of a long side of a cross section of the terminal of the power semiconductor element.

4. 4. The power semiconductor module according to claim 3, wherein a plurality of the flexible portions are provided on each of the two parallel sides.

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