JP2017077140A - Power converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power converter in which, even when a beam for bonding is scanned from a terminal of a semiconductor module or a bus bar in an oblique direction and irradiated, a bonding between these terminals is stable.SOLUTION: A power converter 1 includes: a plurality of adjoining semiconductor modules 10; and a bus bar having terminals 21 respectively bonded to terminals 11 of the semiconductor modules 10. Each of the terminals 11 of the semiconductor modules 10 or the terminals 21 of the bus bars has a concavo-convex portion 23 in a region 22 irradiated with the beam 60 for bonding. An inclination of a surface of the concavo-convex portion 23 is formed to be increased as a distance from a beam source of the beam 60 for bonding is increased.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a power converter.

  A power conversion device that performs AC / DC conversion of power, voltage conversion, and the like is used in hybrid vehicles. Patent Document 1 describes that in a power conversion device, terminals of a plurality of semiconductor modules of an inverter and a boost converter are connected to terminals of a bus bar.

JP 2012-249552 A

  In the power converter according to the background art, plate-like terminals of a plurality of semiconductor modules are arranged adjacent to each other. For this reason, when these terminals and the bus bar plate-shaped terminals are brought into contact with each other and joined by welding with laser light, it is necessary to irradiate the bus bar terminals while scanning the laser light obliquely from above. .

  The angle formed between the incident direction of the laser beam and the normal of the terminal surface (hereinafter referred to as “laser incident angle”) differs depending on the irradiation position on the terminal surface of the bus bar, and the reflectance of the laser beam depends on the irradiation position. Because of the difference, it was considered that when the laser light irradiation amount is constant, bonding failure such as non-bonding between the terminals or laser light penetrating the terminal may occur depending on the irradiation position.

  The present invention has been made to solve such a problem, and even when a beam for bonding is scanned and irradiated from an oblique direction of a terminal of a semiconductor module or a bus bar, the bonding between these terminals is not performed. An object is to provide a stable power conversion device.

  The power conversion device according to the present invention includes a plurality of semiconductor modules arranged adjacent to each other and a bus bar having terminals respectively joined to terminals of the plurality of semiconductor modules, and the terminals of the semiconductor module or the terminals of the bus bar are The surface irradiated with the beam for bonding has an uneven portion, and the inclination of the surface of the uneven portion is formed so as to increase as the distance from the beam source of the beam for bonding increases.

  According to the present invention, even when a beam for bonding is scanned and irradiated from an oblique direction of a terminal of a semiconductor module or a bus bar, a power conversion device in which the bonding between these terminals is stable can be provided.

It is a figure for demonstrating joining between the terminals 11 and 21 of the power converter device 1 which concerns on Embodiment 1. FIG. It is another figure for demonstrating joining between the terminals 11 and 21 of the power converter device 1 which concerns on Embodiment 1. FIG. 4 is a diagram for explaining a cross-sectional shape of a laser irradiation region 22 according to Embodiment 1. FIG. It is a figure which shows the relationship between the irradiation position of the laser beam 60 which concerns on Embodiment 1, and angle (alpha) and (beta). It is a figure which shows the relationship between the irradiation position of the laser beam 60 which concerns on Embodiment 2, and reflection based on a surface state. It is a figure which shows the relationship between the irradiation position of the laser beam based on Embodiment 2, and the reflectance of a laser beam.

Hereinafter, the power converter according to each embodiment will be described with reference to the drawings.
(Embodiment 1)
The power conversion device according to the first embodiment is provided with a substantially triangular wave-shaped uneven portion in a region (hereinafter referred to as “laser irradiation region”) that scans and irradiates a laser beam on the surface of a bus bar terminal. In any part of the region, the laser incident angle is set to approximately 0 degrees, and when the laser light irradiation amount is constant, the reflected light amount of the laser light is substantially constant in the entire laser irradiation region. A stable joint between the terminals is obtained.

  The power conversion device according to the first embodiment includes a power conversion device according to the background art such as a plurality of semiconductor modules, capacitors, and a bus bar that electrically connects the plurality of semiconductor modules and the capacitors constituting the inverter or boost converter. In the present specification, illustration and description of details of each component of the power conversion device according to the first embodiment are omitted. For details of each configuration of the power conversion device, refer to Patent Document 1, for example.

FIG. 1 is a diagram for explaining the connection between the terminals 11 and 21 of the power conversion device 1 according to the first embodiment.
A plurality of semiconductor modules (semiconductor cards) 10 are disposed adjacent to each other in a case (case) 40 of the power conversion device 1, and between the semiconductor modules 10, a semiconductor module 10 is cooled. Each cooler 30 is arranged. That is, the semiconductor modules 10 are stacked in multiple stages via the cooler 30 in the housing 40 of the power conversion device 1.

  When the plate-like power terminal (electrode) 11 of the semiconductor module 10 and the plate-like terminal (electrode) 21 of a bus bar (not shown) for energizing the terminal 11 are joined by welding, the terminal 11 And a terminal 21 are brought into contact with each other, and a laser beam 60 output from a fixed laser light source (not shown) is irradiated from a diagonally upward direction of the terminal 21 through a laser beam lens 61 such as a galvano lens and scanned on the surface of the terminal 21. To do.

  FIG. 2 is another diagram for explaining the connection between the terminals 11 and 21 of the power conversion device 1 according to the first embodiment. It is the figure expanded centering on the part enclosed with the elliptical broken line of FIG. A part of the bus bar terminal 21 is indicated by hatching, which is intended to make the laser irradiation region 22 easy to understand, which means that this part is composed of another part or material. is not. The terminals 11 of the semiconductor module 10 and the bus bar terminals 21 are made of copper, aluminum, iron, or the like.

  As apparent from FIG. 2, if the surface of the laser irradiation region 22 is flat, the laser incident angle θ when the laser beam 60 is scanned on the upper portion (A part) of the laser irradiation region 22 is small, When the laser beam 60 is scanned in the lower portion (C portion) of the laser irradiation region 22, the laser incident angle θ is large, and the laser incident angle θ varies greatly depending on the irradiation position (A portion to C portion). For this reason, the reflectance of the laser beam 60 also varies greatly depending on the irradiation position of the laser beam 60, and the stability (uniformity) of the joint by welding may be lost. Therefore, the laser irradiation region 22 according to the first embodiment has a substantially triangular wave-shaped concavo-convex portion to be described below so that the laser incident angle θ is as close to 0 degrees as possible, that is, the laser beam 60 is Incidence is made as perpendicular to the surface of the terminal 21 as possible.

  FIG. 3 is a diagram for explaining a cross-sectional shape of the laser irradiation region 22 according to the first embodiment. It is the figure which expanded the hatching part of FIG. FIG. 3A shows a cross section of the upper portion of the laser irradiation region 22 (that is, A portion in FIG. 2), and FIG. 3B shows a cross section of the central portion of the laser irradiation region 22 (B portion in FIG. 2). FIG. 3C shows a cross section of the lower portion (C portion in FIG. 2) of the laser irradiation region 22.

  In addition, in order to make the description easy to understand in this specification, a plane including the laser irradiation region 22 when the laser irradiation region 22 has no uneven portion and the surface is flat is referred to as a “virtual terminal plane”. The normal of the virtual terminal plane is called “virtual terminal normal”. For example, the alternate long and short dash line a in FIG. 3A indicates the position of a plane parallel to the virtual terminal plane, and the alternate long and short dash line b indicates the direction of the virtual terminal normal.

As shown in FIG. 3A, in the upper portion of the laser irradiation region 22, the surface of the uneven portion (fine structure portion) 23A has a small number of uneven portions per unit area, and the angle β1 formed with the virtual terminal normal is large. The inclination is small with respect to the virtual terminal plane.
As shown in FIG. 3B, in the central portion of the laser irradiation region 22, the surface of the uneven portion 23B has a slightly larger number of uneven portions per unit area, and the angle β2 formed with the virtual terminal normal is larger than the angle β1. And the inclination is slightly larger than the virtual terminal plane.

Further, as shown in FIG. 3C, in the lower portion of the laser irradiation region 22, the surface of the uneven portion 23C has a large number of uneven portions per unit area, and the angle β3 formed with the virtual terminal normal is larger than the angle β2. Is smaller and has a larger inclination with respect to the virtual terminal plane.
With such a configuration of the uneven portion 23, the angles α1 to α3 formed by the incident direction of the laser beam 60 and the surface of the uneven portion 23 are close to 90 degrees, and the laser incident angles θ1 to θ3 are close to 0 degrees, respectively. .

  The uneven portion 23 is formed such that the height difference of the unevenness on the surface is about several μm to several mm by performing processing such as machining, pressing, laser processing, etching, etc. on the terminal 21 of the bus bar.

FIG. 4 is a diagram showing the relationship between the irradiation position of the laser beam 60 and the angles α and β according to the first embodiment.
As the irradiation position of the laser beam 60 becomes lower (A portion → C portion), the angle β formed between the incident direction of the laser beam 60 and the virtual terminal normal is reduced, and the incident direction of the laser beam 60 and the uneven portion 23 are reduced. The angle α formed with the surface is maintained close to 90 degrees.

As described above, the surface of the concavo-convex portion 23 is formed so as to gradually increase with respect to the virtual terminal plane from the upper side to the lower side of the laser irradiation region 22, so that the laser can be obtained at any position in the laser irradiation region 22. The incident angle θ is set to approximately 0 degrees, the laser reflectivities are approximately equal, and a stable joint between the terminals 11 and 21 can be obtained.
That is, the power conversion device 1 according to the first embodiment can suppress the reflection of the laser beam 60 in the laser irradiation region 22, and the terminal 11, even if the incident angle θ of the laser beam 60 to the virtual terminal plane increases. 21 can be joined, the pitch of the arrangement between the semiconductor modules 10 can be reduced, and the power converter can be miniaturized.

In the power conversion device 1 according to the first embodiment, the concavo-convex portion 23 has a substantially triangular wave shape, but the incident direction of the laser beam 60 and the concavo-convex portion 23 surface form from the upper side to the lower side of the laser irradiation region 22. Any shape can be used as long as the angle α can be close to 90 degrees. For example, the uneven portion 23 may have a substantially sinusoidal shape.
Moreover, in the power converter device 1 which concerns on this Embodiment 1, although the surface of the terminal 21 of a bus-bar was processed and the uneven | corrugated | grooved part 23 was provided, the uneven | corrugated | grooved part 23 or a convex part (bump part) seems to be on the surface from the beginning. A bus bar may be manufactured.

Further, in the power conversion device 1 according to the first embodiment, the uneven portion 23 is provided on the surface of the bus bar terminal 21 and the uneven portion 23 is irradiated with the laser beam 60, but the surface of the terminal 11 of the semiconductor module 10 is uneven. A portion may be provided, and the uneven portion of the terminal 11 of the semiconductor module 10 may be irradiated with the laser beam 60.
In the power conversion device 1 according to the first embodiment, the junction between the terminals 11 and 21 is performed using the laser beam 60, but the junction between the terminals 11 and 21 may be performed using an electron beam. . That is, the terminals 11 and 21 may be bonded using a beam for bonding such as a laser beam or an electron beam.

  As described above, the power conversion device 1 according to the first embodiment includes the plurality of semiconductor modules 10 arranged adjacent to each other and the terminals 21 respectively joined to the terminals 11 of the plurality of semiconductor modules 10. A bus bar, and the terminal 11 of the semiconductor module 10 or the terminal 21 of the bus bar has an uneven portion 23 in a region 22 irradiated with a beam 60 for bonding, and the inclination of the surface of the uneven portion 23 is a beam for bonding. It is formed so as to increase as the distance from the beam source 60 increases.

  With such a configuration, even when the beam for bonding is scanned and irradiated from the oblique direction of the terminals of the semiconductor module or the bus bar, a power conversion device in which the bonding between these terminals is stable can be provided.

(Embodiment 2)
The power conversion device 1 according to the first embodiment is provided with the substantially triangular wave-shaped uneven portion 23 in the laser irradiation region 22 to stabilize the bonding between the terminals 11 and 21. Such a power conversion device performs a surface treatment on the laser irradiation region so that the reflectance of the laser beam does not change even if the incident angle of the laser beam changes from the upper part to the lower part of the laser irradiation region. When the light irradiation amount is constant, the reflected light amount of the laser light is substantially constant in the entire laser irradiation region so as to obtain a stable joint between the terminals.
The power conversion device according to the second embodiment also has a configuration approximately equivalent to that of the power conversion device according to the background art, and in this specification, details of each configuration of the power conversion device according to the second embodiment are described. The illustration and description of are omitted.

  FIG. 5 is a diagram showing the relationship between the irradiation position of the laser beam 60 and the reflection based on the surface state according to the second embodiment. 5A shows an upper portion (A ′ portion (a portion corresponding to the A portion in FIG. 2)) of the laser irradiation region 122, and FIG. 5B shows a central portion (B ′ portion (a portion of the laser irradiation region 122). FIG. 5C shows a lower part (C ′ part (part corresponding to part C in FIG. 2)) of the laser irradiation region 122.

The laser irradiation region 122 has been subjected to surface treatment, but the surface of the laser irradiation region 122 has no unevenness and is substantially flat.
As shown in FIG. 5A, the incident angle θ1 is small in the upper portion of the laser irradiation region 122, but the surface treatment is applied so that a large amount of laser light is reflected at this incident angle, and the incident laser A part of the light 60 is reflected.

Further, as shown in FIG. 5B, the incident angle θ2 is larger than the incident angle θ1 in the central portion of the laser irradiation region 122, but the surface treatment is performed so that the laser beam is slightly reflected at this incident angle. A part of the incident laser beam 60 is also reflected.
Further, as shown in FIG. 5C, in the lower portion of the laser irradiation region 122, the incident angle θ3 is further larger than the incident angle θ2, but the surface is formed so as not to reflect the laser beam so much at the incident angle. Processing is performed, and a part of the incident laser beam 60 is also reflected.

As described above, the surface treatment is performed on the terminal of the bus bar so that the reflected light amount of the laser beam 60, that is, the reflectance of the laser beam 60 becomes substantially equal from the upper part to the lower part of the laser irradiation region 122. I have to.

Table 1 is a table for explaining the surface treatment of the power conversion device according to the second embodiment.
As the irradiation position of the laser beam 60 becomes lower (A ′ portion → C ′ portion), the surface treatment is applied to the terminal of the bus bar so that the reflection of the laser beam based on the surface state becomes smaller.
As the surface treatment method, oxidation, plating, painting or the like can be employed. For example, it is used that the reflectivity of laser light decreases when the degree of oxidation increases. Further, azo metal complex salts and phthalocyanines can be used as the dye, and carbon black, organic pigments and the like can be used as the pigment.

FIG. 6 is a diagram showing the relationship between the laser light irradiation position and the laser light reflectance according to the second embodiment.
When there is no surface treatment, the reflectance of the laser beam increases as the irradiation position of the laser beam 60 becomes lower (A ′ portion → C ′ portion), and the amount of reflected laser light increases. When there is a surface treatment, the reflectance of the laser light is substantially constant even when the irradiation position of the laser light 60 is on the lower side, and the amount of the reflected laser light is also substantially constant.

  As described above, at least surface treatment is performed on the laser irradiation region 122 so that the reflection of the laser beam based on the surface state is reduced from the upper side to the lower side of the laser irradiation region 122, thereby the inside of the laser irradiation region 122. In any of the positions, the reflectance of the laser beam is made substantially constant regardless of the change in the incident angle θ, and a stable joint between the terminals can be obtained.

  That is, in the power conversion device according to the second embodiment, the reflectance of the laser beam 60 can be constant in the laser irradiation region 122, and even if the incident angle θ of the laser beam 60 to the virtual terminal plane increases, The stable joining between 21 becomes possible, the arrangement pitch between the semiconductor modules can be reduced, and the power converter can be downsized.

  In the power conversion device according to the second embodiment, the bus bar terminal is subjected to surface treatment and the laser beam is irradiated to the bus bar terminal. However, the semiconductor module terminal is subjected to surface treatment, and the laser beam is applied to the semiconductor module. The terminal may be irradiated.

DESCRIPTION OF SYMBOLS 1 Power converter 10 Semiconductor module 11 Terminal 21 of semiconductor module Bus terminal 22 and 122 Laser irradiation area | region 23 Uneven part 60 Laser beam

Claims (1)

A plurality of semiconductor modules arranged adjacent to each other;
A bus bar having terminals respectively joined to the terminals of the plurality of semiconductor modules;
The terminal of the semiconductor module or the terminal of the bus bar has a concavo-convex portion in a region irradiated with the beam for bonding,
The power conversion device is configured such that the inclination of the surface of the concavo-convex portion increases as the distance from the beam source of the beam for the bonding increases.

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