JP2006086438A - Bus bar structure for semiconductor module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a bus bar structure for a semiconductor module, the wiring inductance of which is reduced and wherein high-temperature molding resin will not flow between positive/negative power supply connection terminals of each of switching elements at insert molding, and wherein the insulation member between the connection terminals will not deteriorate. <P>SOLUTION: In the bus bar structure for connecting each switching element of the semiconductor module to a power supply, positive/negative power supply connection terminals of each switching element are formed integrally and contained in a resin case, and located to provide facing regions, wherein at least parts of mutual principal faces of the connection terminal face nearly in parallel, an insulating material is located between the facing regions, and insert molding is carried out so that no resin is in contact with the insulating member. The size of the insulating member in the length direction is selected to be smaller than the size of the positive/negative power supply connection terminals, and the insulating material is located in the inside, and a folded part or a step difference part is formed to both ends, in the width direction of one or both the positive/negative power supply connection terminals. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a bus bar (plate body made of a conductive material) structure for connecting each switching element of a semiconductor module including a plurality of switching elements to a power source.

In recent years, electric vehicles and hybrid electric vehicles have attracted attention as environmentally friendly vehicles, and their practical application is progressing. For example, a hybrid electric vehicle is equipped with an electric drive system in addition to a conventional engine.
This electric drive system includes a battery as a DC power source, an inverter as a power converter, an AC motor as an electric motor, and the like. In a vehicle equipped with the system, direct current power supplied from a battery is converted into alternating current power by an inverter device, and an alternating current motor is driven to obtain a driving force of the vehicle.

  FIG. 14 is a circuit configuration diagram of a general electric drive system mounted on a vehicle. This electric drive system is driven by a battery 1 in which a plurality of nickel-metal hydride batteries, lithium ion batteries, etc. are connected in series, an inverter device 2 that converts DC power of the battery 1 into AC power, and AC power of the inverter device 2 It is comprised with AC motor 3 grade | etc.,.

The inverter device 2 shown in FIG. 14 includes a switching module 6 having a three-phase configuration in which semiconductor switching elements 5 such as IGBTs are bridge-connected and a driver circuit unit 7 for driving the switching module 6.
The driver circuit unit 7 drives the inverter device 2 based on a signal 8a from a host controller (not shown), and transmits a signal 8b to the controller side when an abnormality occurs in the inverter device 2. Fulfill.
The positive electrode terminal and the negative electrode terminal of the switching element bridge-connected in the switching module 6 are respectively a positive power source connection terminal 9 (hereinafter referred to as (+) bus bar 9) and a negative power source connection terminal 10 (hereinafter referred to as (−) bus bar). 10)), and the ends of the (+) bus bar 9 and the (-) bus bar 10 are used as the P terminal 11 and the N terminal 12 for the input terminal of the inverter device 2.
The P terminal 11 and the N terminal 12 of the inverter device 2 are electrically connected to the positive electrode and the negative electrode of the battery 1, respectively, and a smoothing capacitor 4 for smoothing the DC power supplied from the battery 1 is connected in parallel. Has been.
For the wiring connecting the P terminal 11 and N terminal 12 of the switching module 6 and the positive and negative electrodes of the smoothing capacitor 4, plate-like bus bars 13 and 14 made of a conductive material are used.
On the other hand, the U, V, and W terminals that are terminals on the output side of the switching module 6 are electrically connected to the input terminals of the three-phase AC motor 3.

Usually, since an electric drive system mounted on a vehicle needs to generate a very large driving force, a large current on the order of several hundreds of A is used for driving an AC motor by an inverter device.
For this reason, since the switching element of the inverter device is normally driven at a high speed operation of 10 kHz, it is connected to the (+) bus bar 9, the (−) bus bar 10 and the smoothing capacitor 4 which are internal wirings of the switching module 6. The wiring inductance due to the bus bars 13 and 14 cannot be ignored.
The inductance due to these connection wirings causes a large surge voltage to be applied to the switching element during switching. Therefore, it is required to reduce the wiring inductance with respect to the power source of the switching element.

In order to reduce the wiring inductance, it is necessary to arrange the smoothing capacitor 4 and the switching module 6 close to each other. Thereby, since it becomes possible to shorten a connection wiring, wiring inductance can be reduced.
Further, by arranging the reciprocating lines of the connection wiring close to each other, mutual inductance can be generated to reduce the wiring inductance, and the (+) bus bar 9 and the (−) bus bar 10 which are internal wirings of the switching module 6. Alternatively, the bus bars 13 and 14 connected to the smoothing capacitor 4 are usually arranged close to each other in a laminated structure.
Furthermore, in order to arrange the bus bars 13 and 14 that connect the smoothing capacitor 4 and the switching module 6 close to each other, for example, insulating paper such as Nomex (made by DuPont) is sandwiched between the bus bars 13 and 14 at intervals of about 0.2 mm. If they are arranged close to each other, the wiring inductance can be reduced to several tens of nH.

In addition, a structure has been proposed in which the wiring inductance is reduced by sandwiching a high dielectric member between two bus bars connecting the smoothing capacitor and the switching module. By sandwiching a material having a dielectric constant higher than that of Nomex between the bus bars and having a function as a capacitor, the effect of absorbing a surge voltage when the switching element is switched can be enhanced (for example, Patent Documents). 1).
JP 2003-319665 A

However, even if the smoothing capacitor and the switching module can be arranged close to each other and the wiring inductance can be reduced by the above structure, the wiring from the input terminal to the switching element in the module is integrally formed with the resin by insert molding. Therefore, it cannot be arranged close to each other, and the wiring inductance cannot be reduced.
FIG. 15 shows an internal structure diagram of the switching module 6.
Usually, the internal wiring from the P terminal 11 and the N terminal 12 of the switching module 6 to the positive electrode end and the negative electrode end of the switching element 5 is a bus bar processed with an oxygen-free copper plate, and is on the (+) terminal side of the switching element. The (+) bus bar 9 to be connected and the (−) bus bar 10 connected to the (−) terminal side are laminated.
Here, it is preferable that the distance between the two bus bars is narrow, but if it is too narrow, the (+) bus bar 9 and the (−) bus bar 10 come into contact with each other and the insulation distance cannot be taken.

In consideration of the above, insert molding was attempted with (+) bus bar 9 and (-) bus bar 10 sandwiched between Nomex sandwiched between the bus bars connecting the smoothing capacitor and the switching module. Since a very high temperature resin of about 320 ° C. is injected at the time of molding, there is a problem in that the resin contacts and the nomex is deformed and a uniform insulating effect cannot be obtained.
In addition, instead of insulating paper such as Nomex, an insulating resin such as varnish was applied around the bus bar and placed in layers, and insert molding was attempted, but by contacting with a resin near the heat resistance temperature of the insulating resin, There is a problem in that insulation deterioration occurs and the insulation performance deteriorates.

  Due to the above problems, between the (+) bus bar connected to the (+) terminal side of the switching element and the (−) bus bar connected to the (−) terminal side for the purpose of reducing the wiring inductance. Even when placed close together, high temperature molding resin does not flow around the bus bar during insert molding, and neither contact nor insulation failure occurs between the bus bars. Therefore, there has been a demand for a structure that does not deform or deteriorate the insulation.

The present invention solves the above-mentioned problem, a positive power source connection terminal ((+) bus bar) for connecting the positive end of the switching element of a semiconductor module composed of a plurality of switching elements to the positive side of the power source, In the bus bar structure of the semiconductor module, in which the negative electrode power connection terminal ((−) bus bar) that connects the negative electrode end of the switching element to the negative electrode side of the power source is integrally molded and stored in the resin molded case.
The positive power source connection terminal ((+) bus bar) and the negative power source connection terminal ((−) bus bar) are arranged so that at least a part of each main surface has a facing region facing substantially parallel, the facing region The bus bar structure of the semiconductor module is characterized in that an insulating member is disposed therebetween and insert molding is performed so that the resin does not contact the insulating member.

Further, the longitudinal dimension of the insulating member is shorter than the longitudinal dimension of the positive and negative power supply connection terminals, and is disposed on the inner side of both longitudinal ends of both connection terminals,
In addition, the semiconductor module bus bar structure is characterized in that a bent portion or a stepped portion is formed at both ends in the width direction of either one or both of the positive electrode and the negative power supply connection terminal.

  Furthermore, the bus bar structure of the semiconductor module is characterized in that the insulating member is an insulating paper, an insulating film, or an insulating resin.

  A positioning guide hole is provided in any two or more of the positive power supply connection terminal, the negative power supply connection terminal, and the insulating member, and a resin having a positioning pin for an insert molding die or a pin structure in the guide hole. A bus bar structure of a semiconductor module, wherein insert molding is performed in a state where a molding spacer is inserted and positioning is performed.

  In addition, one or both of the positive power supply connection terminal and the negative power supply connection terminal described above have a stepped portion, and the stepped portion and a resin molded spacer having a pin structure are fitted to each other. It is a bus bar structure.

  Furthermore, the bus bar structure of the semiconductor module is characterized in that the positive power source connection terminal and the negative power source connection terminal are drawn out of the resin case with an insulating member sandwiched between the opposing regions.

By using the above configuration, the (+) and (-) bus bars arranged inside the switching module can be arranged close to each other, and the wiring inductance is reduced, so that the surge voltage at the time of switching is reduced. Can do.
In addition, by placing a thin insulating paper, insulating film, and insulating resin between the bus bars and placing them in close proximity, it becomes the same structure as interposing a capacitor with a small capacity between the (+) and (-) bus bars. Acts as a snubber capacitor that absorbs voltage.
Further, even when the (+) and (-) bus bars are arranged close to each other with an interval of 1 mm or less, high temperature molding resin does not flow around the bus bar during insert molding, and the case contact portion and the case contact portion at the end of the bus bar Therefore, poor contact or insulation failure between both bus bars does not occur.
Since the positioning guide holes for arranging the insulating member are provided, the insulation performance between the wirings due to the displacement of the insulating member is not deteriorated, and a stable quality semiconductor module can be provided. It becomes.
Moreover, since the height dimension of the switching module can be reduced by reducing the thickness of the insulating member sandwiched between the (+) and (−) bus bars, a thinned semiconductor module can be provided.
Furthermore, by pulling out the (+) and (-) bus bars and insulating members that are insert-molded into the resin case to the outside of the resin case, the semiconductor module can be directly connected to the smoothing capacitor and the wiring inductance is reduced. Provision is possible.

  Embodiments of the present invention will be described below with reference to the drawings.

[Example 1] (FIGS. 1-7, forming bent portions or stepped portions at both ends of the bus bar, using positioning pins or spacers)
As an example of the bus bar structure of the semiconductor module using the present invention, FIG. 1 shows an example in which insert molding is performed with nomex sandwiched between (+) bus bar and (−) bus bar as insulating paper.
1A shows a resin case in which an insulating paper 19 is sandwiched between a (+) bus bar 9 and a (−) bus bar 10 and is insert-molded. FIGS. 1B and 1C are insert molds. The procedure for integrally molding is shown below.
In FIG. 1 (a), the insulating paper 19 is sandwiched between the (+) bus bar 9 and the (-) bus bar 10 and the wire bonding region is opened, and the resin case 17 is laminated and insert-molded. Taking the structure. The resin case 17A takes out the end portions of the (+) bus bar 9 and the (−) bus bar 10 as the P terminal 11 and the N terminal 12 for external connection, respectively.
As a resin case manufacturing process, the upper mold 21a and the lower mold 21b are fitted with the insulating paper 19 sandwiched between the (+) bus bar 9 and the (-) bus bar 10 (FIG. 1 (b)), and the resin is Injection and integral molding are performed (FIG. 1 (c)).
Here, since the contact portions of the (+) bus bar 9, the (−) bus bar 10, and the insulating paper 19 are surrounded by the upper mold 21a and the lower mold 21b, the molding resin is only in the injection portion 17A of the resin case. The resin does not contact the contact portions of the (+) bus bar 9, the (−) bus bar 10, and the insulating paper 19. Therefore, both ends in the longitudinal direction of the (+) bus bar 9 and the (−) bus bar 10 are integrally formed with the resin case 17A.

FIG. 2 shows a case where resin is injected and the bus bar and the resin case are integrated in order to form a bridging portion in a region excluding the wire bonding area in the lower surface portion of the (+) bus bar 9 and the upper surface portion of the (−) bus bar 10. This is an example of further strengthening.
Fig.2 (a) is a figure which shows the upper surface side of a resin case, FIG.2 (b) is a figure which shows a lower surface side. As a manufacturing method of the resin case, the upper die 21a is provided with the recesses 17c and 17d in the regions of the upper die 21a and the lower die 21b corresponding to the lower part of the (+) bus bar 9 and the upper part of the (−) bus bar 10, respectively. And the lower mold 21b are fitted (FIG. 2 (c)), and resin is injected to perform integral molding (FIG. 2 (d)).
Here, as in FIG. 1, the contact portions of the (+) bus bar 9, the (−) bus bar 10, and the insulating paper 19 are surrounded by the upper mold 21a and the lower mold 21b. The resin does not contact the contact portions of the (+) bus bar 9, the (−) bus bar 10, and the insulating paper 19.

Next, a process of manufacturing a semiconductor module by integrally molding a heat sink on which an insert resin case portion and a semiconductor switching element are mounted will be described.
The insert-molded resin case 17A is integrated with the heat dissipation substrate 16 (FIG. 3A) on which the insulating substrate 15 on which the semiconductor switching element 5 is previously mounted is mounted (FIG. 3B).
As shown in FIG. 3A, the insulating substrate 15 on which the semiconductor switching element 5 is mounted is mounted on and integrated with the heat dissipation substrate 16. Then, the heat dissipation board 16 on which the semiconductor switching element 5 is mounted is joined and integrated with the resin case 17A in a state where the adhesive resin is applied to the periphery.

4A is a plan view of the switching module 6, FIG. 4B is an XX cross-sectional view, and FIG. 4C is a YY cross-sectional view. In FIG. 4A, the (+) bus bar 9 and the (−) bus bar 10 connected to the power source are stacked in the center of the switching module 6 with the insulating paper 19 sandwiched therebetween, and U, V on the left side thereof. , W-phase upper arm, and U, V, and W-phase lower arm insulating substrates are arranged on the right side. The insulating substrate 15 and the (+) bus bar 9, and the semiconductor switching element 5 and the (−) bus bar 10 are connected by an aluminum wire 18.
Here, between the (+) bus bar 9 and the (−) bus bar 10, a nomex having a thickness of 0.2 mm is used as the insulating paper 19. Compared with the state in which the insulation distance is secured, the insulation layer thickness between the two bus bars is 1/5 or less, and the (+) bus bar 9 and the (-) bus bar 10 can be arranged close to each other, and the wiring inductance can be greatly reduced.
Here, at the end portions of both bus bars, the insulating paper 19 is not encapsulated and molded in a resin case, so the longitudinal dimension of the insulating paper 19 is made shorter than the (+) bus bar 9 and the (−) bus bar 10, The (+) bus bar 9 and the (−) bus bar 10 are provided with bent portions (non-opposing portions) in the lateral direction at the end portions, and the insulation between the two bus bars is secured by taking a space insulation distance.

  Further, as shown in FIG. 5, as a method of treating the end portions of the (+) bus bar 9 and the (−) bus bar 10, a vertical stepped portion is provided only at the end portion of the (−) bus bar 10. It is also possible to secure insulation between the two bus bars by forming a space insulation distance of about 1 mm at the end of the bus bar 10 and integrally forming the spacer 23 therebetween.

Here, a supplementary explanation of Nomex will be given.
Nomex is an insulating paper mainly composed of an aramid fiber, and is an insulating paper having a thickness of 0.2 mm and a pressure resistance of 30 kV or more, and has a heat resistant temperature of about 220 ° C. Therefore, it is suitable for insulating paper between bus bars for 600-1200V inverters.

  In FIG. 4A, the (+) bus bar 9, the (-) bus bar 10, and the insulating paper 19 are provided with two positioning guide holes 20, and the positioning is accurately performed based on the guide holes. Therefore, it can arrange | position in the state which maintained the fixed insulation distance, without contacting between both bus-bars. The positioning method will be described below.

6A and 6B are diagrams showing the arrangement of the (+) bus bar 9 and the (−) bus bar 10 and the insulating paper 19 in FIG. 4. FIG. 6A is a perspective view, and FIG. It is the side view seen from A direction of a).
In FIG. 6, a resin molding die 21 is provided with positioning pins 22 in advance, and positioning is performed by inserting these pins in the order of (+) bus bar 9, insulating paper 19, and (-) bus bar 10. Is going. At this time, the guide hole 20 of the insulating paper 19 is made sufficiently small with respect to the guide hole 20 of the (+) bus bar 9 and the (−) bus bar 10, and a step corresponding to the diameter of each guide hole is provided on the pin 22. Thus, positioning can be performed while ensuring accuracy.

Moreover, the arrangement of the (+) bus bar 9, the (-) bus bar 10, and the insulating paper 19 according to another embodiment is shown in FIGS.
FIG. 7 (a) is a perspective view of these, and FIG. 7 (b) is a side view seen from the direction A of FIG. 7 (a).
In FIGS. 7A and 7B, a resin-molded spacer 23 is used as a positioning pin, which is inserted in the order of (+) bus bar 9, insulating paper 19, and (-) bus bar. Positioning. At this time, in the same manner as described above, the guide hole 20 of the insulating paper is made sufficiently small with respect to the guide hole 20 of the (+) bus bar 9 and (−) bus bar 10, and a step corresponding to the diameter of each guide hole is provided in the spacer 23. By attaching the mark, it is possible to perform positioning while ensuring accuracy.

Regarding the above positioning method, in the example of FIG. 6, in order to remove the pin of the mold after resin molding, it is necessary to consider whether the insulating paper sandwiched between both bus bars is sufficiently fixed.
On the other hand, in the example of FIG. 7, the spacer 23 is required as a separate part. However, since the insulating paper sandwiched between both bus bars is fixed by the spacer, more reliable fixing is possible.

[Example 2] (FIGS. 8 and 9, use of stepped portions and positioning spacers at both ends of the bus bar)
8 (a) and 8 (b) show the positioning of both bus bars and insulating paper by fitting spacers to the ends of both bus bars (+) and (-) bus bars with insulating paper sandwiched between them. An example in which both fixing and insert integral molding are carried out is shown.
FIG. 8A is a perspective view showing the arrangement of the (+) bus bar 9 and the (−) bus bar 10 and the insulating paper 19 in FIG. 5, and FIG. It is the side view seen from A direction.
The (+) bus bar 9, the (−) bus bar 10, and the insulating paper 19 in FIG. 8A are provided with positioning guide holes 20, and the (−) bus bar 10 is provided with a step. Then, a spacer 23 previously molded with resin is inserted between the (−) bus bar 10 and the insulating paper 19 for positioning. At this time, by setting the guide hole diameters provided in the (+) bus bar 9 and the insulating paper 19 to be substantially the same, the positional deviation between the two can be set small.
Here, since the end portions of the (+) bus bar 9 and the (−) bus bar 10 have a step structure and sandwich the spacer, the distance between the two bus bars is as far as 1 mm as in the conventional case. In a location close to the switching element, the proximity arrangement is performed with 0.2 mm of insulating paper interposed therebetween, so that the effect of reducing inductance can be sufficiently obtained.
Furthermore, by using the stepped portion provided on the (−) bus bar as a bus bar bending structure near the lead-out portion of the P and N terminals, it is possible to cope with it without the need to set the bus bar size particularly long.
Further, when these both bus bars are integrally formed with the resin case, as shown in FIG. 8B, the (+) bus bar 9, the (-) bus bar 10, and a part of the spacer 23 are integrated with the resin case. As a result, the insulating paper 19 does not come into contact with the resin injected into the mold in a high temperature state, so that the insulating paper 19 does not suffer from a problem of deformation or a decrease in withstand voltage.

FIG. 9 shows another embodiment, FIG. 9 (a) is a perspective view thereof, and FIG. 9 (b) is a side view seen from the direction A of FIG. 9 (a) after resin molding.
In FIG. 9, positioning guide holes 20 are provided in the (+) bus bar 9 and the (−) bus bar 10 and the insulating paper 19, and the (+) bus bar 9 and the (−) bus bar 10 are formed in steps. .
Then, the previously formed spacers 23a and 23b are sandwiched using the positioning guide holes of the insulating paper 19 and combined in a U-shape, and the (+) bus bar 9 and (-) bus bar 10 are It is positioned by inserting it into the positioning hole.
As in the case of FIG. 8, the end portions of the (+) bus bar 9 and (−) bus bar 10 have a step and sandwich the spacer, so that the distance between both bus bars is about 1 mm as in the conventional case. In other locations close to the switching element, the proximity arrangement is made with 0.2 mm of insulating paper in between, so that the effect of reducing inductance can be sufficiently obtained.
Further, by utilizing the stepped portions provided on both bus bars as a bus bar bending structure near the lead-out portion of the P and N terminals, it is possible to cope with it without having to set the bus bar size to be particularly long.
Further, when these both bus bars are integrally formed with the resin case, as shown in FIG. 9 (b), the (+) bus bar 9, the (-) bus bar 10, and a part of the spacer 23 are integrated with the resin case. As a result, the insulating paper 19 does not come into contact with the resin injected into the mold at a high temperature, so that the insulating paper 19 does not suffer from a problem of deformation or a decrease in withstand voltage.
Also, compared to the case of FIG. 8, the spacer 23 is divided into two parts, so the number of components increases, but also for the resin that may flow through the interface between the spacers 23a, 23b and both bus bars, The insulating paper 19 does not come into contact, and a more reliable insert resin case can be manufactured.

[Example 3] (FIGS. 10 and 11, stepped portions at both ends of bus bar, use of positioning spacer, L-shaped bus bar taken out of resin case)
FIG. 10 shows a bus bar structure of a semiconductor module according to another embodiment of the present invention.
FIG. 10A is a plan view of the switching module 6, and FIG. 10B is a cross-sectional view taken along the line XX of FIG.
In FIG. 10A, the L-shaped (+) bus bar 9 and the (−) bus bar 10 connected to the power source are stacked on the left end of the switching module 6 with the insulating paper 19 sandwiched therebetween, and in the center. Insulating substrates of U, V, and W phases are arranged.
The resin case 17A is formed by insert molding with the (+) bus bar 9 and the (−) bus bar 10 in a state where the wire bonding region is exposed, and the ends of the (+) bus bar 9 and the (−) bus bar 10 are integrated. Are taken out as a P terminal 11 and an N terminal 12 for external connection.
The insulating substrate 15 is mounted by soldering on the heat dissipation substrate 16 with the semiconductor switching element 5 mounted. The insulating substrate 15 and the (+) bus bar 9 or the semiconductor switching element 5 and the (+) bus bar 9 are connected by an aluminum wire 18.
Between the (+) bus bar 9 and the (−) bus bar 10, a nomex having a thickness of 0.2 mm is used as the insulating paper 19, so a conventional molding resin is injected to ensure an insulation distance of 1 mm or more. Compared with the state where it was, the insulation layer thickness between both bus bars becomes 1/5 or less, and the (+) bus bar 9 and the (-) bus bar 10 can be arranged close to each other, so that the wiring inductance can be greatly reduced.
However, since the insulating paper 19 is not encapsulated in the resin case at the ends of both bus bars, the longitudinal dimension of the insulating paper 19 is made shorter than the (+) bus bar 9 and the (−) bus bar 10, (-) Steps are provided at both ends of the bus bar 10, and the insulation between the two bus bars is secured by taking an insulation distance of about 1 mm.

Next, a positioning method will be described.
11 is a view showing the arrangement of (+) bus bar 9 and (−) bus bar 10 and insulating paper 19 in FIG. 10, FIG. 11 (a) is a perspective view, and FIG. 11 (b) is after resin molding. 11A is a side view seen from the A direction, and FIG. 11C is a side view seen from the B direction.
In FIG. 11, a guide hole 20 for positioning is provided in the (+) bus bar 9, the (−) bus bar 10, and the insulating paper 19, and a step portion is provided in the (−) bus bar 10. Then, a spacer 23 previously molded with resin is inserted between the (−) bus bar 10 and the insulating paper 19 for positioning. At this time, by making the diameters of the (+) bus bar and the positioning guide holes provided in the insulating paper 19 substantially the same, the positional deviation between them can be set small.
Here, since the end of the (−) bus bar 10 in FIG. 11 has a step structure and sandwiches the spacer, the distance between the bus bars is as far as 1 mm as in the conventional case, but is close to other switching elements. In the place, since the adjacent arrangement is performed with 0.2 mm of insulating paper interposed therebetween, the effect of reducing inductance can be sufficiently obtained.
When the both bus bars are integrally formed with the resin case, as shown in FIG. 11B, (+) part of the bus bar 9 and the spacer 23 and (−) the upper surface region of the bus bar 10 (however, the wire (Excluding the bonding region) is integrated with the resin case, and the insulating paper 19 does not come into contact with the resin injected into the mold in a high temperature state. There is no problem.
Further, in FIG. 11C, the resin is injected into the region 17e and is integrally formed by contacting the (−) bus bar 10 and the spacer 23. At this time, the spacer 23 is in contact with the resin and the insulating paper 19. Therefore, the region of the resin case 17A is not in direct contact with the insulating paper.
Further, as another embodiment, the spacers 23a and 23b used in FIG. 9 are sandwiched using the positioning guide holes of the insulating paper 19 and combined in a U shape, and then the (+) bus bar 9 and the (−) bus bar 10 are A method of fitting from above and below can also be used.

[Example 4] (FIG. 12, use of stepped portions, positioning spacers and insulating resin at both ends of the bus bar)
FIG. 12 shows a bus bar structure of a semiconductor module according to another embodiment of the present invention.
FIG. 12A is a perspective view showing the arrangement of the (+) bus bar 9 and the (−) bus bar 10 and the insulating resin 24 in FIG. 1, and FIG. It is the side view seen from A direction of a). In FIG. 12A, the insulating resin 24 is a varnish, and is applied in advance to an area of the (+) bus bar 9 excluding the wire bonding region.
Thus, when the insulating resin is previously applied to the (+) bus bar or the (−) bus bar, there is no need to provide a guide hole for positioning between the insulating resin and both bus bars. It is only necessary to provide a guide hole for positioning between 9 and (−) bus bar 10. Therefore, as shown in FIG. 12, the (+) bus bar 9 and the (−) bus bar 10 are provided with positioning guide holes 20, and the (−) bus bar 10 is provided with a stepped portion.
Then, the resin-molded spacer 23 is placed between the (+) bus bar 9 and the (-) bus bar 10 so as to intersect the application region of the insulating resin 24, and is integrally molded by fitting. Here, as shown in FIG. 12 (b), the (+) bus bar 9, the (-) bus bar 10, and a part of the spacer 23 are integrated with the resin case, so that the insulating resin 24 is in a high temperature state. In this case, the insulating resin 24 is not softened and the breakdown voltage is not lowered.

[Example 5] (FIG. 13, L-shaped bus bar is taken out of resin case and positioning spacer is used)
FIG. 13 shows a bus bar structure of a semiconductor module according to another embodiment of the present invention.
13A is a plan view showing a structure in which the (+) bus bar 9 and the (−) bus bar 10 are taken out from the switching module 6 and directly connected to the smoothing capacitor 4, and FIG. 13B is a plan view of FIG. It is XX sectional drawing of).
In FIG. 13A, both the (+) bus bar 9 and the (−) bus bar 10 of the switching module 6 are L-shaped, and are taken out of the resin case with the insulating paper 19 sandwiched between the opposing areas. . The (+) bus bar 9 and the (−) bus bar 10, which are the end portions of the P terminal 11 and the N terminal 12, are directly screwed to the smoothing capacitor 4.
By adopting such a structure, the (+) bus bar 9 and the (−) bus bar 10 respectively connected to the positive electrode and the negative electrode of the switching element are disposed via insulating paper having a thickness of about 0.2 mm. The inductance can be reduced, and the connection bus bars 13 and 14 when the (+) bus bar 9 and the (−) bus bar 10 are connected to the smoothing capacitor 4 can be dispensed with, including screw fixing points when the bus bar is connected. Inductance can be greatly reduced.

In said Examples 1-5, it described about the example which uses an insulating paper or apply | coats insulating resin as an insulating member pinched | interposed between bus bars. Here, instead of insulating paper, an insulating film used in a film capacitor or the like can be used. Examples that can be used for the insulating film include polypropylene (hereinafter referred to as PP), polyphenylene sulfide (hereinafter referred to as PPS), polyethylene terephthalate (hereinafter referred to as PET), and the like. For example, PPS is an insulating film having a thickness of 0.2 mm and a withstand voltage of about 1000 V, and has an extremely high insulating performance.
However, since the above-mentioned film is easily broken by a sharp blade, it is desirable to use it by devising such as stacking a plurality of films and sandwiching them between bus bars.

《Effect confirmation by numerical value》
Here, the thickness of the insulating layer between the (+) bus bar 9 and the (−) bus bar 10 is d, the dielectric constant is ε _r, and the opposing area of the (+) bus bar 9 and the (−) bus bar 10 is S. Then, the capacitance C formed by the facing surfaces of the (+) bus bar 9 and the (−) bus bar 10 is expressed by the following equation.

Here, the capacitance C1 and the thickness d2 when the facing area S is fixed and an insulating member having a thickness d1 and a relative dielectric constant _εr1 is inserted between the (+) bus bar 9 and the (−) bus bar 10 are shown. Substituting the electrostatic capacitance C2 when an insulating member having a dielectric constant ε _r2 is inserted into Equation 1 to calculate C1 / C2, the following equation is obtained.

Therefore, the capacitance C1 when using Nomex having a thickness d1 = 0.2 mm and a relative dielectric constant ε _r1 = 2.6, and a thickness d2 = 1 mm and a relative dielectric constant ε of a resin layer obtained by conventional insert molding. _When Fortron 6165A4 (polyplastics PPS resin) with _r2 = 5.7 is used, the ratio to the capacitance C2 is C1 / C2≈2.3 times, and (+) bus bar 9 and (− ) Capacitance between the bus bars 10 can be greatly increased, and a role as a snubber capacitor that absorbs a surge voltage can be exhibited.
Moreover, the effect as a capacitor | condenser can also be heightened using an insulating film with a higher dielectric constant instead of Nomex.
For example, two PPS films having a relative dielectric constant ε _r1 = 2.2 having a thickness of 15 μm and a withstand voltage of about 1000 V are stacked (thickness d1 = 0.03 mm) between the (+) bus bar 9 and the (−) bus bar 10. Uses Fortron 6165A4 (polyplastics PPS resin) with electrostatic capacity C1 when abutting and resin layer by conventional insert molding with thickness d2 = 1 mm and relative dielectric constant ε _r2 = 5.7 In this case, the ratio to the capacitance C2 is C1 / C2≈12.9 times, and it can serve as a snubber capacitor that absorbs the surge voltage.
Further, as the insulating resin shown in FIG. 12A, a polyester varnish having a relative dielectric constant ε _r1 = 3.8 and a coating thickness d ₁ = 0.3 mm and a conventional capacitance C1 are shown. The ratio of the resin layer formed by insert molding to the capacitance C2 can be C1 / C2≈2.2 times.
Although varnish has lower scratch resistance than Nomex, the same effect can be obtained by applying the varnish thicker than Nomex.

Further, a trial calculation is performed with respect to an inductance reduction effect by arranging the (+) bus bar 9 and the (-) bus bar 10 in close proximity.
If the opposing width of (+) bus bar 9 and (-) bus bar 10 is h, the opposing length is l, and the distance (thickness of the insulating layer) between both bus bars is s, (+) bus bar 9 and (-) The wiring inductance L of the parallel copper plate of the bus bar 10 is expressed by the following equation.

In FIG. 4, for (+) bus bar 9 and (−) bus bar 10 having opposing areas of width h = 10 mm and length l = 150 mm, a nomex having a thickness s1 = 0.2 mm is sandwiched between both bus bars. The wiring inductance L1 and the wiring inductance L2 with the resin layer thickness s2 = 1 mm by the conventional insert molding are calculated using Equation 3.
When the parameter s / h for determining the correlation coefficient K _sh is calculated, s1 / h = 0.02 when using Nomex, and s2 / h = when using the resin layer thickness by conventional insert molding. 0.1.
For example, as to the correlation coefficient, KNOEPFEL, “PULSED HIGH MANETIC FIELDS: NORTH HOLLAND PUBLISHING COMPANY”, p. Using the correlation coefficient calculation diagram described in H.323, the correlation coefficient K _sh ≈0.9 can be set in the region of s / h ≦ 0.1. Therefore, by substituting this into Equation 3 and calculating the wiring inductance for the case where the nomex is sandwiched and the case where the resin layer thickness is obtained by conventional insert molding, L1 = 3.4 (nH), L2 = 17 ( nH), and the inductance reduction effect ΔL = 13.6 (nH) can be obtained.
The surge voltage reduction effect ΔV due to the inductance reduction effect ΔL = 13.6 (nH) is calculated by the following equation.

Here, in the IGBT of the inverter circuit, the current change rate dI / dt = −6 (A / ns) when the switching element is turned off when the collector current I _{C is} 300 A, and ΔL = 13.6 (nH in Equation 4) ), The surge voltage reduction effect of ΔV≈82 (V) can be found.

  In addition, elements, such as IGBT, FET, GaN, can be used as a semiconductor switching element in the said Example.

FIG. 1A is a plan view of a switching unit according to an embodiment of the present invention, and FIGS. 1B and 1C are cross-sectional views showing a procedure for integrally forming the unit with an insert molding die. is there. 2 (a) and 2 (b) are plan views of the switching unit according to another embodiment of the present invention ((a) is a top view, (b) is a state when viewed from the bottom surface), and FIG. ), (C) are cross-sectional views showing a procedure when the insert molding die is integrally formed with the unit. It is sectional drawing which shows the procedure at the time of integrally forming the heat sink which mounted the semiconductor switching element in the switching unit by the Example of this invention. 4A is a plan view of a switching module according to an embodiment of the present invention, FIG. 4B is a sectional view taken along line XX of FIG. 4A, and FIG. 4C is YY. It is sectional drawing by a line. FIG. 6 is an assembly view of a (+) bus bar, an insulating member, and a (−) bus bar according to another embodiment of the present invention. FIG. 6A is an assembly view of a (+) bus bar, an insulating member, and a (−) bus bar according to the embodiment of the present invention, and FIG. It is. FIG. 7A is an assembly view of a (+) bus bar, an insulating member, and a (−) bus bar according to another embodiment of the present invention, and FIG. 7B is viewed from the direction A in FIG. 7A. It is a side view. FIG. 8A is an assembly view of a (+) bus bar, an insulating member, and a (−) bus bar according to another embodiment of the present invention, and FIG. 8B is viewed from the direction A in FIG. 8A. It is a side view. FIG. 9A is an assembly view of a (+) bus bar, an insulating member, and a (−) bus bar according to another embodiment of the present invention, and FIG. 9B is viewed from the direction A in FIG. 9A. It is a side view. FIG. 10A is a plan view of a switching module according to another embodiment of the present invention, and FIG. 10B is a cross-sectional view taken along line XX of FIG. FIG. 11 (a) is an assembly view of a (+) bus bar, an insulating member, and a (−) bus bar according to another embodiment of the present invention, and FIG. 11 (b) is viewed from the direction A in FIG. 11 (a). A side view, FIG.11 (c) is the side view seen from the B direction of Fig.11 (a). FIG. 12A is an assembly view of a (+) bus bar, an insulating member, and a (−) bus bar according to another embodiment of the present invention, and FIG. 12B is viewed from the direction A in FIG. It is a side view. FIG. 13A is a plan view of a switching module according to another embodiment of the present invention, and FIG. 13B is a cross-sectional view taken along line XX of FIG. It is the figure which showed the circuit structure of the general electric drive system. It is sectional drawing of the switching module by a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery 2 Inverter apparatus 3 AC motor 4 Smoothing capacitor 5 Switching element 6 Switching module 7 Driver circuit unit 8a, 8b Control signal 9 Positive power supply connection terminal ((+) bus bar)
10 Negative power supply connection terminal ((-) bus bar)
11 P terminal 12 N terminal 13 Bus bar 14 Bus bar 15 Insulating substrate 16 Heat radiating substrate 17A Resin case 17B Bridge (upper surface)
17C Bridge (bottom)
17a Resin injection point (top of mold)
17b Resin injection point (underside of mold)
17c Resin injection point (mold upper surface, bridging part)
17d Resin injection point (mold lower surface, bridging part)
17e Resin injection point (on the upper surface of the mold, the end of the bridge)
18 Aluminum wire 19 Insulating paper 20 Positioning guide hole 21 Insert molding die 22 Positioning pin 23 Positioning spacer 24 Insulating resin 25 Bolt

Claims (6)

A positive power supply connection terminal for connecting the positive terminal of the switching element of the semiconductor module composed of a plurality of switching elements to the positive side of the power supply; and a negative power supply connection terminal for connecting the negative terminal of the switching element to the negative side of the power supply In a bus bar structure of a semiconductor module formed by integrally molding and storing in a resin molded case,
The positive power supply connection terminal and the negative power supply connection terminal are arranged so that at least a part of each main surface has a facing region facing substantially parallel,
An insulating member is disposed between the opposing regions,
A bus bar structure for a semiconductor module, wherein the insulating member is insert-molded so that resin does not come into contact therewith. The longitudinal dimension of the insulating member according to claim 1 is shorter than the longitudinal dimension of the positive and negative power supply connection terminals, and is arranged on the inner side of both longitudinal ends of both connection terminals,
And the bus-bar structure of the semiconductor module characterized by forming the bending part or the level | step-difference part in the width direction both ends of any one or both of a positive electrode or a negative electrode power supply connection terminal.   The bus bar structure of a semiconductor module, wherein the insulating member according to claim 1 is an insulating paper, an insulating film, or an insulating resin. A positioning guide hole is provided in any two or more of the positive power source connection terminal, the negative power source connection terminal, and the insulating member according to claim 1,
A bus bar structure for a semiconductor module, wherein a positioning pin of an insert molding die or a resin molding spacer having a pin structure is inserted into the guide hole, and insert molding is performed in a positioned state.   5. A semiconductor module, wherein either one or both of the positive power supply connection terminal and the negative power supply connection terminal according to claim 4 have a stepped portion, and the stepped portion and a resin molded spacer having a pin structure are fitted. Bus bar structure.   A bus bar structure for a semiconductor module, wherein the positive power supply connection terminal and the negative power supply connection terminal according to claim 1 are drawn out of the resin case with an insulating member sandwiched between opposing regions thereof.

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