JP2021022697A - Semiconductor module - Google Patents

Abstract

To ensure creepage distances and clearance distances between a busbar and adjacent terminals when installing the busbar.SOLUTION: A semiconductor module includes a case in which a semiconductor element is housed inside and the whole is molded with resin, a first terminal that is provided on an upper part of the case and to which a flat and elongated metal conductor busbar is attached, a second terminal that is provided on the upper part of the case and is adjacent to the first terminal, and a rib provided between the first terminal and the second terminal. The rib has a protrusion that protrudes toward the busbar.SELECTED DRAWING: Figure 1

Description

The present invention relates to a semiconductor module, and more particularly to a semiconductor module in which a bus bar is attached to a resin case.

A semiconductor module mounted on an electric device is designed so that the creepage distance and the spatial distance between the terminals of the module can be secured to a predetermined size. The creepage distance is the shortest distance along the surface of the insulator between the terminals, and the spatial distance is the shortest distance through the space between the terminals.

A semiconductor module is configured by accommodating semiconductor elements such as diodes and transistors in a resin case, arranging a metal base plate on the bottom of the case and arranging a plurality of terminals on the top of the case. It has a package structure as a whole.

In a semiconductor module having such a structure, the following prior art has been proposed in order to secure the creepage distance and the spatial distance between the terminals provided on the upper part of the case.

First, ribs (insulating wall portions) are provided between the terminals to increase the creepage distance and the space distance between the terminals (Patent Document 1). Second, a groove is provided on the surface of the case to increase the creepage distance (Patent Document 2).

Japanese Unexamined Patent Publication No. 6-21603 Japanese Unexamined Patent Publication No. 2003-303939

However, it may be difficult to secure a sufficient creepage distance and spatial distance in the configuration provided with the ribs and grooves as described above. For example, in a configuration in which a plurality of semiconductor modules are arranged and one bus bar is screwed to a common terminal of each semiconductor module, there are the following problems.

That is, when the bus bar is attached, the bus bar may be attached out of a predetermined position. At this time, the bus bar may come into contact with the surface of the rib. Then, the creepage distance and the spatial distance between the second terminal adjacent to the first terminal to which the bus bar is attached and the bus bar become equal to or less than the preset design values. In particular, when a groove is provided to increase the creepage distance, the effect of this groove disappears.

An object of the present invention is to provide a semiconductor module capable of reliably securing a creepage distance and a clearance distance between a second terminal adjacent to a first terminal to which a bus bar is attached and the bus bar when the bus bar is attached.

The present invention includes a case in which a semiconductor element is housed inside and the whole is molded of resin.
A first terminal provided on the upper part of the case to which a flat and elongated metal conductor busbar is attached.
A second terminal provided on the upper part of the case and adjacent to the first terminal,
A rib provided between the first terminal and the second terminal is provided.
The rib has a protrusion protruding toward the bus bar.

A first terminal and a second terminal are provided on the upper portion of the case, and ribs are provided between these terminals. When the bus bar is attached to the first terminal, the bus bar is in a movable range up to a position in contact with the protrusion of the rib. The busbar does not come into contact with the rib surface because the rib protrusion is an obstacle. As a result, it is possible to prevent the bus bar from coming into contact with the surface of the rib. When the bus bar comes into contact with the surface of the rib, the creepage distance and the clearance distance between the bus bar and the second terminal are shortened. However, in the present invention, the busbar does not contact the surface of the rib due to the protrusion of the rib. Therefore, the creepage distance and the space distance between the bus bar and the second terminal can be set as predetermined design values.

By providing an inclined surface on the protrusion, it becomes easy to pull out the entire rib and case in the vertical direction when molding the rib and the case with resin. In addition, the busbar can be easily mounted because it can be lowered to the mounting position along the inclined surface.

The protrusions can be provided near the center of the rib or at a plurality of places. If it is installed in multiple places, it will prevent the busbar from rotating when it is attached.

By providing a groove around the first terminal and the second terminal, the creepage distance between the bus bar and the second terminal can be increased by the creepage length of the groove. The creepage distance that can be earned by this groove can be surely secured because the bus bar cannot move further to the rib side due to the protrusion of the rib.

In the present invention, since the bus bar can be prevented from coming into contact with the surface of the rib by providing the protrusion on the rib, the first terminal for screwing the bus bar or the bus bar and the second terminal adjacent thereto are used. The creepage distance and the space distance between them can be surely set as the design values.

It is a perspective view of the semiconductor module which is an embodiment of this invention. It is a top view of the semiconductor module. It is a circuit diagram of a semiconductor module. FIG. 2 is a cross-sectional view taken along the line AB. The top view when the four semiconductor modules are arranged in the second direction (Y direction) at regular intervals and the bus bar is attached is shown. (A) and (B) are a diagram showing a creepage distance in a plan view of a semiconductor module and a diagram showing a creepage distance in a CD sectional view, respectively. It is a figure which shows the creepage distance when the wall 70 is not cut out. (A) and (B) are a diagram showing a spatial surface distance in a plan view of a semiconductor module and a diagram showing a spatial distance in a CD sectional view, respectively. (A) to (D) are diagrams showing other embodiments, respectively.

FIG. 1 is a perspective view of a semiconductor module according to an embodiment of the present invention. FIG. 2 is a plan view of the semiconductor module.

This semiconductor module is a rectangular parallelepiped resin case 1 and a first terminal 2 for screwing, which is provided in the case 1 and is arranged at predetermined intervals in the longitudinal direction, which is the first direction (X direction). , A second terminal 3 and a third terminal 4 are provided.

The case 1 has a first terminal surface 21, a second terminal surface 31, and a third terminal surface on which a first terminal 2, a second terminal 3, and a third terminal 4 are placed, respectively. 41 is formed. The first terminal surface 21 mounts the first terminal 2, the second terminal surface 31 mounts the second terminal 3, and the third terminal surface 41 mounts the third terminal 4. .. Each of the terminals 2 to 4 is formed by inserting a metallic vertical piece preformed into a terminal shape into the case 1 and bending the upper end portion thereof. A screw insertion hole is formed in the center of each of the terminals 2 to 4.

Two diodes D1 and D2 are housed as semiconductors in the case 1. FIG. 3 is a circuit diagram. The cathode of the diode D1 and the cathode of the diode D2 are connected to form a common terminal C, and the anode of the diode D1 is formed as the first anode terminal A and the anode of the diode D2 is formed as the second anode terminal B. ing.

The common terminal C is connected to the first terminal 2 in the case 1. The first anode terminal A is connected to the second terminal 3 in the case 1. The second anode terminal B is connected to the third terminal 4 in the case 1. The first terminal 2 is a terminal to which the bus bar is attached by screwing as described later. The second and third terminals 3 and 4 are terminals to which the end of the cable is attached by screwing. On the terminal surfaces 21, 31 and 41, screw portions 20, 30 and 40 are formed below the terminals 2 to 4. To screw the bus bar or cable end to terminals 2 to 4, place the screw hole of the bus bar or cable end on each terminal 2 to 4, and screw the bus bar or cable end from the top 20 to 20 through a washer or the like. Tighten to 40.

Screwing portions 100 and 101 for fixing the case are provided at both ends of the case 1 in the first direction (X direction). The screwing portions 100 and 101 are for fixing the case 1 to the substrate in the housing of the electric device with screws.

The case 1 is provided with a first rib 5 and a second rib 6 on the upper portion thereof. The first rib 5 and the second rib 6 are provided in a second direction (Y direction) orthogonal to the first direction (X direction). The first rib 5 is provided between the first terminal 2 and the second terminal 3, and the second rib 6 is provided between the second terminal 3 and the third terminal 4. These ribs 5 and 6 are for gaining creepage distance and clearance distance between each terminal. Further, these ribs 5 and 6 are integrally molded with the case 1.

The first rib 5 is provided with a protrusion 51 at the center of the surface 50. The protrusion 51 faces the first terminal 2 for the bus bar. The protrusion 51 is formed integrally with the rib 5 in the vertical direction at the central portion of the surface 50 in the second direction (Y direction). Further, the upper end portion of the protrusion 51 is a slope 51a that inclines downward from the upper end. The lower portion continuous with the slope 51a is a vertical plane. The protrusion 51 is thus composed of a slope 51a and a vertical plane continuous with the slope 51a. As a result, the slope 51a has a draft, and the mold can be easily removed during molding.

On the upper surface of the case 1, a first groove 7, a second groove 8, and a third groove 9 are formed around the terminals 2 to 4, and more specifically, around the terminal surfaces 21, 31, and 41. It is provided. The first groove 7 is provided in front of and behind the first terminal 2 and on the left side of the first terminal 2 (FIG. 1: first rib 5 side). The second groove 8 is provided in front of and behind the second terminal 3 and on the left and right sides of the second terminal 3 (FIG. 1: the second rib 6 side and the first rib 5 side). The third groove 9 is provided in front of and behind the third terminal 4 and on the right side of the third terminal 4 (FIG. 1: side of the second rib 6).

The first groove 7 includes a first wall 70 provided on the outside of the case 1. A notch 71 is formed in the central portion of the first wall 70. The first wall 70 and the notch 71 are provided before and after the first terminal 2. The notch 71 is provided for draining water from the first groove 7. The second groove 8 includes a second wall 80 provided on the outside of the case 1. A notch 81 is formed in the central portion of the second wall 80. The second wall 80 and the notch 81 are provided before and after the second terminal 3. The notch 81 is provided for draining the groove 8. The third groove 9 includes a third wall 90 provided on the outside of the case 1. A notch 91 is formed in the central portion of the third wall 90. The third wall 90 and the notch 91 are provided before and after the third terminal 4. The notch 91 is provided for draining water from the third groove 9.

The height of each wall 70, 80, 90 is set lower than that of each terminal surface 21, 31, 41.

FIG. 4 is a cross-sectional view taken along the line AB of FIG. As shown in the figure, the height of the first terminal surface 21 (height from the bottom surface of the case 1) is H1, the height of the first wall 70 is H2, and H1-H2 = h1. The height (thickness) of the first terminal 2 is h2. h1 + h2 = h3. h3 is the distance between the bottom surface of the bus bar 10 and the top surface of the first wall 70. Setting the distance between the bottom surface of the bus bar 10 and the top surface of the wall 70 as h3 is an important configuration for surely setting the creepage distance d1 as a design value, as will be described later.

The semiconductor module having the above configuration is mounted on a substrate provided in the electric device, and then the bus bar and the cable end are screwed to each semiconductor module.

FIG. 5 shows a plan view when four semiconductor modules are arranged in a second direction (Y direction) at regular intervals and a bus bar is attached.

The four semiconductor modules M1 to M4 are screwed to the substrate in the housing of the electric device by the screwing portions 100 and 101 provided at both ends of the case 1, respectively.

The bus bar 10 of a flat and elongated metal conductor comes into contact with the protrusion 51 provided on the first rib of each case 1 when it is closest to the rib 5 in FIG. Normally, the bus bar 10 does not come into contact with the protrusion 51 of the rib 5 when it is attached.

Next, the creepage distance d1 and the spatial distance d2 between the first terminal 2 and the second terminal 3 adjacent thereto will be described with reference to FIGS. 6 to 8. The creepage distance d1 is the shortest distance along the surface of the insulator between the terminals 2 and 3, and the space distance d2 is the shortest distance passing through the space between the terminals 2 and 3.

FIG. 6A is a plan view of one case 1 and shows the creepage distance d1 from the upper surface of the case 1. Further, FIG. 6B shows a cross-sectional view taken along the line CD of FIG. 6A. In these figures, the points A, B, C, and D indicate the positions of the grooves 7 or 8 in which the creepage distance d1 is measured in the vertical direction.

When considering the creepage distance, whether or not there is a spatial distance of less than 1 mm is the subject of consideration. That is, when the spatial distance is less than 1 mm, the spatial distance becomes a part of the creepage distance. Therefore, in that part, the creepage distance is no longer the distance along the insulator. Here, when the thickness of the first terminal 2 is less than 1 mm, the distance h2 between the lower surface of the bus bar 10 and the first terminal surface 21 is less than 1 mm when the bus bar 10 is attached. Therefore, the distance h2 becomes a part of the creepage distance d1 (see FIG. 4). That is, when the measurement of the creepage distance d1 is started from the first terminal 2 side, the creepage distance d1 is the bottom surface of the bus bar 10 ⇒ the first terminal surface 21 ⇒ the first groove 7 ⇒ the side surface of the first rib 5. The total distance from the second groove 8 ⇒ the second terminal surface 31 ⇒ the second terminal 3. In FIG. 4, the distance shown by the thick line indicates a part of the creepage distance d1.

Hereinafter, when the thickness of the first terminal 2 is less than 1 mm, the bottom surface of the bus bar 10 becomes the starting point of the creepage distance d1.

As shown in FIG. 4, the distance h2 between the bottom surface of the bus bar 10 and the first terminal surface 21 is less than 1 mm. Therefore, insulation cannot be secured between the first terminal 2 and the bus bar 10. Therefore, the start point P at the creepage distance d1 is not the end of the first terminal 2, but the bottom surface of the bus bar 10 facing the first terminal surface 21. The creepage distance d1 reaches the upper surface of the first wall 70 from the point P via the first terminal surface 21 and from the point A to the point B of the first groove 7.

On the other hand, the height H2 of the first wall 70 is formed to be lower than the height H1 of the first terminal surface 21 by h1. The height of the first terminal 2 is h2. Therefore, by setting H2 to a height such that the distance h3 (= h1 + h2) between the bottom surface of the bus bar 10 and the upper surface of the first wall 70 is 1 mm or more, the spatial distance of h3 becomes a part of the creepage distance. It doesn't become. That is, the creepage distance d1 is measured along the upper surface of the first wall 70.

For the above reason, the creepage distance d1 is the distances (1) to (13) below in FIGS. 4 and 6.

(1) Starting point P on the bottom surface of the bus bar 10 (see FIG. 4)
(2) ⇒ A (go down the wall of the first groove 7 vertically)
(3) ⇒ Bottom surface of the first groove 7 (passes diagonally through the bottom surface of the first groove 7)
(4) ⇒ B (go up the wall surface of the first groove 7 diagonally)
(5) ⇒ 1st wall 70 (passes diagonally through the upper surface of the 1st wall 70)
(6) ⇒ E1 (side surface of the first rib 5)
(7) ⇒ E2 (passes horizontally on the outside of the side surface of the first rib 5)
(8) ⇒ Second wall 80 (passes diagonally through the upper surface of the second wall 80)
(9) ⇒ C (go down the wall of the second groove 8 diagonally)
(10) ⇒ Bottom surface of the second groove 8 (passes diagonally through the bottom surface of the groove 8)
(11) ⇒ D (go up the wall surface of the second groove 8 diagonally)
(12) ⇒ Second terminal surface 31
(13) ⇒ Second terminal 3
In FIG. 6, the creepage distance d1 is shown to descend (or increase) vertically in B to D, but in reality, it descends (or increases) diagonally as in (4), (9), and (11) above. ..

As a modification, when the thickness of the first terminal 2 is 1 mm or more, h2 is a sufficiently long distance. In this case, the starting point P at the creepage distance d1 is the left end (FIG. 4) of the first terminal 2. The creepage distance d1 is the following (1a) and (1b) instead of the above (1).

(1a) Starting point P (not shown) at the left end (FIG. 4) of the first terminal 2.
(1b) Distance connecting the first terminal surface 21 to the first groove 7 As described above, in the embodiment shown in FIG. 4, the creepage distance d1 is the starting point P on the bottom surface of the bus bar 10 (see FIG. 4). Therefore, the grooves 7 and 8 are used as paths on both the left and right sides of the first rib 5. As a result, a sufficient creepage distance d1 can be secured.

As a reference example, the creepage distance d1 when the heights of the first wall 70 and the first terminal surface 21 are the same, that is, when H1 = H2 will be described. In such a case, the creepage distance d1 becomes short. The reason for this will be described with reference to FIG.

In FIG. 7, although the first groove 7 is provided, the height H2 of the first wall 70 and the height H1 of the first terminal surface 21 are the same. As described above, if h2 is less than 1 mm, the spatial distance of h2 is measured as part of the creepage distance. Therefore, the starting point P'of the creepage distance d1 is the bottom surface of the bus bar 10 facing the end of the first wall 70. That is, the groove 7 provided for gaining the creepage distance cannot be a part of the creepage distance d1.

Specifically, the creepage distance d1 is the following (14) to (16) from the above (1) to (7). The same applies to the reference example after (8) above.

(14) Starting point P'on the bottom surface of the bus bar 10 (see FIG. 7)
(15) ⇒ F (descends vertically from P'to the outer end of the upper surface of the first wall 70.)
(16) ⇒ Passes straight from the first wall 70 to the side surface of the first rib 5.

As described above, in the reference example, as compared with FIG. 4 showing the present embodiment, the distance connecting vertically and horizontally in the first groove 7 cannot be utilized, and the creepage distance d1 becomes shorter.

As another reference example, the creepage distance d1 when the protrusion 51 is not provided on the first rib 5 will be described. In such a configuration, the bus bar 10 may come into contact with the surface of the first rib 5. Then, when the bus bar 10 comes into contact with the surface of the first rib 5, the starting point of the creepage distance d1 becomes the contact point regardless of the height of the first wall 70. Therefore, the creepage distance d1 is even shorter.

In the present embodiment, as shown in FIG. 4, the height of the first wall 70 is lowered as in H2, so that the starting point P of the creepage distance d1 faces the first terminal surface 21 of the bus bar 10. (Position facing A inside the first groove 7). As a result, the first groove 7 is surely a part of the creepage distance d1.

As described above, in the present embodiment, the bus bar 10 is attached by providing the protrusion 51 of the first rib 5 and making the height of the first wall 70 lower than that of the first terminal surface 21. In this case, the first groove 7 can be a part of the creepage distance d1. Then, if the height H2 of the first wall 70 is set to a height at which h1 + h2 = h3 is 1 mm or more, the safety standard can be satisfied. If h1 is set to 1 mm or more, h1 + h2> 1 mm. Therefore, even if the first terminal 2 is changed to a thin terminal of h2, the creepage distance d1 that ensures insulation can be secured.

Next, the space distance d2 will be described.

FIG. 8A is a top view of one case 1, and shows the space distance d2 from the upper surface of the case 1 from the upper surface. Further, FIG. 5 (B) shows a cross-sectional view taken along the line CD of FIG. 5 (A).

The space distance d2 is the shortest distance through the space between the first terminal 2 and the second terminal 3 adjacent thereto. In the state where the bus bar 10 is attached, as shown in the figure, Q at the right end of the bus bar 10 facing the side surface of the first rib 5 is the starting point. Therefore, the spatial distance d2 is Q⇒ bus bar 10. Side view ⇒ The shortest distance in space to the second terminal 3. In front view, the spatial distance d2 is horizontal as shown in FIG. 8 (B).

From FIGS. 8A and 8B, the space distance d2 can be reliably secured by the thickness of the protrusion 51 of the first rib 5.

FIG. 9 shows another embodiment. 9 (A) to 9 (C) show the shape of the protrusion 51. In FIG. 9A, the protrusion 51 is triangular in front view, and in FIG. 9B, the protrusion 51 is formed downward from the central portion of the first rib 5 in front view. FIG. 9C is a plan view, and protrusions 51 are formed near the left and right sides of the rib 5. According to this, when the bus bar 10 is attached, it becomes a detent. In this case, the two protrusions 511 and 512 need to be slightly separated from the left and right ends of the rib 5 as shown and inside the first front and rear grooves 7. Further, the two protrusions 511 and 512 need to be formed at positions facing the first terminal surface 21. This is to surely obtain the effect of the first groove 7 (gaining the creepage distance). FIG. 9D shows an example in which the position of the screw hole 120 of the bus bar 10 is slightly eccentric to the right side. In this example, the bus bar 10 can be attached at a position away from the first rib 5. If the bus bar 10 is to be mounted upside down, the left end portion of the bus bar 10 hits the first rib 5 and the bus bar 10 cannot be mounted. As a result, the creepage distance d1 and the spatial distance d2 can be increased. In addition, it is possible to prevent an error in the mounting direction of the bus bar 10.

As described above, in the present embodiment, by providing the protrusion 51 on the first rib 5, it is possible to reliably secure the creepage distance between the bus bar 10 and the adjacent terminals when the bus bar 10 is attached. Also, the space distance can be increased.

1-Case 2-First terminal 3-Second terminal 4-Third terminal 5-First rib 6-Second rib 51-Protrusion

Claims (6)

A case in which a semiconductor element is housed inside and the whole is molded with resin,
A first terminal provided on the upper part of the case to which a flat and elongated metal conductor busbar is attached.
A second terminal provided on the upper part of the case and adjacent to the first terminal,
A rib provided between the first terminal and the second terminal is provided.
The rib is a semiconductor module provided with a protrusion protruding toward the bus bar. The semiconductor module according to claim 1, wherein the protrusion has an inclined surface that inclines downward from the upper end. The semiconductor module according to claim 2, wherein the protrusion has a vertical surface extending downward from the inclined surface. The semiconductor module according to any one of claims 1 to 3, wherein the protrusion is provided near the center of the rib. The semiconductor module according to any one of claims 1 to 3, wherein the protrusion is provided at a plurality of positions of the rib. The semiconductor module according to any one of claims 1 to 5, wherein a groove is provided around the first terminal and the second terminal.

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