JP6064805B2 - Insulated bus bar and manufacturing method thereof - Google Patents

Description

  The present invention relates to an insulating bus bar used in a large-capacity power converter and a method for manufacturing the same.

Conventionally, in an electrical device using a semiconductor element (power module), an insulating bus bar is sometimes used for connection of a main circuit in order to cope with a higher frequency.
FIG. 9 is a cross-sectional view showing a configuration of a conventional insulating bus bar. As shown in FIG. 9, a conventional insulating bus bar 100 includes a laminated body 130 formed by alternately laminating and laminating flat conductors 110 (110A and 110B) and an insulator 120, and its And a through terminal 140 that penetrates in the thickness direction and is joined to each of the conductors 110A and 110B. The insulation bus bar having such a configuration (hereinafter sometimes referred to as a laminate bus bar) can act as a mutual inductance by narrowing the space between the conductors 110A and 110B, and as a result, the inductance can be reduced.

However, by adopting such a laminated bus bar, it was possible to achieve surge reduction during high-speed switching. Insulated bus bars have been demanded.
Therefore, technologies disclosed in Patent Documents 1 to 4 have been proposed for increasing the breakdown voltage and the heat resistance of such an insulating bus bar.

According to the technique disclosed in Patent Document 1, by using an adhesive layer as a resistor, the electric field around the through hole into which the through terminal is inserted is particularly relaxed in the laminate, and a high breakdown voltage can be expected. Is.
Patent Documents 2 and 3 propose techniques for insulating a case made of a plate-shaped conductor by pouring a molten resin into the case. Patent Document 4 discloses a technique in which a laminated structure is formed using an adhesive layer as a typical structure of a laminated bus bar.

JP 2010-259139 A JP 2010-274602 A JP 2010-274603 A Japanese Patent No. 4618211

Conventional insulating bus bars often use thermoplastic films or sheet-like insulating materials (polypropylene, polyethylene terephthalate, etc.) as laminated insulator materials. In addition, an adhesive layer may be provided in a laminated bus bar using an insulating material made of a high heat resistant polymer sheet or insulating paper.
However, as disclosed in Patent Documents 1 to 3, in an insulating bus bar having a configuration in which an insulator is provided between plate-like conductors, the surface of the insulator follows the surface of the conductor and is joined. There is a problem that mechanical and electrical weak points are caused by the occurrence of the unbonded bonding interface A (see FIG. 9). In addition, the adhesive layer disclosed in Patent Document 4 also has a low insulating performance and becomes a bottleneck of the occurrence of partial discharge and dielectric breakdown. As described above, in the conventional laminated bus bar, the state of the (crimp) bonding interface formed around the through-terminal for connecting the semiconductor element and the presence of the adhesive interface may cause a decrease in the insulation performance. There was room for improvement in higher pressure resistance.
Therefore, the present invention has been made paying attention to the above-mentioned problems, and an object of the present invention is to provide an insulating bus bar having a higher breakdown voltage and a method for manufacturing the same.

In order to solve the above problems, the present inventors have conducted intensive studies. As a result, in order to increase the breakdown voltage of the insulation busbar, the following conditions (a) and (b) that cause a decrease in insulation performance are satisfied. I found it important to meet.
(a) Do not form a bonding interface between a conductor and an insulator, or a bonding interface between insulators.
(b) Do not use an adhesive that does not form an insulating layer. No adhesive layer is provided.

This invention is based on the said knowledge by this inventor, and the aspect with the insulation bus bar of this invention for solving the said subject is the laminated body by which the mesh-shaped conductor and the mesh-shaped insulating sheet were laminated | stacked And a through terminal joined so as to penetrate the laminate,
The mesh conductor, the mesh insulating sheet, and the penetrating terminal are integrally formed of an insulating resin impregnated in each.

With such a configuration, there is no bonding interface between the conductor and the insulating sheet (insulator) and no adhesive layer, and the insulating sheet functions not only as an insulator but also as an adhesive layer. It is possible to provide an insulating bus bar which prevents peeling and has a high withstand voltage.
Here, in the insulating bus bar, the material of the mesh-like insulating sheet may be polypropylene, polyethylene terephthalate, insulating paper impregnated with the insulating resin, or glass fiber.
Moreover, it is preferable that the said insulation bus bar has a creeping distance ensuring part integrated with the said insulating resin.

Further, an aspect of the method for producing an insulating bus bar of the present invention for solving the above problems is a laminate production step of producing a laminate by laminating a mesh-like conductor and a mesh-like insulating sheet,
A through terminal installation step of joining the through terminal so as to penetrate the laminate,
The laminated body in which the through terminals are installed is fixed to a mold, and the insulating resin is evacuated to impregnate the mesh-like conductor and the mesh-like insulating sheet with the insulating resin, respectively. A resin impregnation step integrally formed with the through terminal.

  In this way, a laminated body in which mesh-like insulating sheets (insulators) and mesh-like conductors are alternately laminated is placed in a mold, and the laminate is impregnated with resin by, for example, evacuation, thereby obtaining a plate-like shape. The generation of voids in the insulating region is reduced as compared with the case where the conductor and the plate-like insulator are used. And there is no bonding interface between the conductor and the insulator and the adhesive layer, and since the insulating sheet serves not only as an insulator but also as an adhesive layer, it prevents the conductor and the insulator from peeling off and increases the withstand voltage. In addition, a method of manufacturing an insulated bus bar can be provided.

Here, in the manufacturing method of the insulating bus bar, the material of the mesh-shaped insulating sheet is preferably polypropylene, polyethylene terephthalate, insulating paper impregnated with the insulating resin, or glass fiber.
Moreover, it is preferable that the manufacturing method of the said insulation bus bar forms the creeping distance ensuring part integrated with the said insulating resin in the said oil impregnation process.

  As described above, according to the insulating bus bar of an aspect of the present invention, it is possible to provide an insulating bus bar with higher breakdown voltage and a method for manufacturing the same.

It is sectional drawing which shows the structure in embodiment with the insulation bus bar of this invention. It is sectional drawing which shows the laminated body preparation process in embodiment with the manufacturing method of the insulation bus bar of this invention. It is sectional drawing which shows the penetration terminal installation process in embodiment with the manufacturing method of the insulation bus bar of this invention. It is sectional drawing which shows the resin impregnation process in embodiment with the manufacturing method of the insulation bus bar of this invention. It is sectional drawing which shows the resin impregnation process in embodiment with the manufacturing method of the insulation bus bar of this invention. It is sectional drawing which shows the structure in other embodiment of the insulation bus bar of this invention. It is sectional drawing which shows the resin impregnation process in other embodiment of the manufacturing method of the insulation bus bar of this invention. It is sectional drawing which shows the structure in other embodiment of the insulation bus bar of this invention. It is sectional drawing which shows the structure of the conventional insulation bus bar.

(Insulated bus bar)
Hereinafter, embodiments of the insulating bus bar of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing a configuration in an embodiment of an insulating bus bar of the present invention.
As shown in FIG. 1, the insulating bus bar 1 of this embodiment includes a laminated body 30 in which mesh-like (mesh-like) conductors 10 and mesh-like (mesh-like) insulating sheets 20 are alternately laminated, The laminated body 30 has a through terminal 40 that penetrates the laminated body 30 in the thickness direction and is joined to the mesh conductor 10. The mesh-like conductor 10, the mesh-like insulating sheet 20, and the through terminal 40 are integrally formed by an insulating resin 50 impregnated in each.

Here, the mesh-like conductor 10 is a “conductor having resin impregnation property”, which is formed by flat knitting a conductor made of a metal such as a copper wire and forming a large number of pores (= mesh). It is.
On the other hand, the mesh-like insulating sheet 20 is also an “insulator having resin impregnation” and forms a sheet-like insulator formed in a “mesh” regardless of whether it is intentional or not. is there. The “mesh shape” includes a mesh shape formed intentionally and a fiber shape. The “insulating sheet” may be a sheet-like insulator having a substantially uniform thickness. Examples of such an insulating sheet include glass cloth (mesh shape), glass fiber, and insulating paper (fiber). A so-called prepreg in which a fiber (for example, carbon fiber) is coated with a thermosetting resin is used. May be. Examples of the material for the insulating sheet include polypropylene and polyethylene terephthalate.

  The mesh conductor 10 has a plurality of through holes into which the through terminals 40 are inserted according to the installation positions of the through terminals 50 in the laminate 30 constituted by the mesh conductors 10 and the mesh insulating sheet 20. 11 and 12 are formed. Specifically, the mesh-like conductor 10A is brazed or soldered to the through hole 11A provided with a gap of a separation distance d with respect to a certain through terminal 40A and the other through terminal 40B. A through hole 11B to be joined is formed. On the other hand, the mesh-like conductor 10B is provided with a through hole 11B joined by brazing or soldering to a certain through terminal 40A and a gap with a separation distance d from the other through terminal 40B. A through hole 11A is formed.

On the other hand, a plurality of through holes 21 having the same dimensions corresponding to the cross-sectional shape of the through terminal 40 are formed in the mesh-like insulating sheet 20. The separation distance d of the through holes 21 with respect to the through terminals 40 is preferably smaller than the separation distance d so as to cover the inner peripheral ends of the through holes 11 and 12 of the mesh conductor 10.
In this embodiment, as shown in FIG. 1, the laminate 30 includes a mesh-like insulating sheet 20, a mesh-like conductor 10 </ b> A, a mesh-like insulating sheet 20, a mesh-like conductor 10 </ b> B, and a mesh-like insulation. A mode in which the sheets 20 are stacked in the order is described as an example.

[Separation distance]
The separation distance d (mm) is set according to the maximum potential difference generated in the mesh conductors 10A and 10B. Further, since the separation distance d varies depending on the insulating performance of the insulating resin 50, it is set by the following formula (1). In the following formula (1), V (Vrms) is the maximum potential difference between the mesh conductors 10A and 10B, S (Vrms / mm) is the dielectric strength of the insulating resin 50, and a is a safety factor (however, 3.0 or more) ).
d ≧ (V × a) / S ........... Formula (1)
As an example, when the insulating resin 50 having the maximum potential difference V between the mesh conductors 10A and 10B of 10 kV and the dielectric strength S of 15 kV / mm is used, a separation distance (d) of at least 2 mm or more is calculated.

Thus, according to the insulation bus bar of this embodiment which comprises the mesh-like conductor 10 and the mesh-like insulating sheet 20 impregnated with the insulating resin 50 and constitutes the integrated laminate 30, the periphery of the through terminal 40 is provided. Since there is no bonding interface or adhesive layer, a weak point of insulation (“A” in FIG. 9) is not formed.
In addition, since the laminated structure of the conductor and the insulator is not an adhesive structure between the plate-like body and the plate-like body, the insulating bus bar of the present embodiment is not bonded to the conductor and the insulator even if bending or stress is applied to the insulated bus bar. Is difficult to peel off.
In addition, the insulating bus bar of this embodiment can reduce the manufacturing cost because the mesh conductor 10 and the mesh insulating sheet 20 are integrated with the insulating resin 50 without providing an adhesive layer. .

Furthermore, the insulating bus bar of this embodiment can provide a heat-resistant insulating bus bar by using a thermosetting resin for the insulating resin 50, rather than using a thermoplastic resin as in Patent Documents 1 to 4. .
In addition, the insulation bus bar of the present embodiment maintains a constant distance between the mesh conductors by the mesh insulation sheet, has a low inductance compared to a general bus bar, and is an integrated structure, so that it is easy to install. It also has the characteristics of the conventional insulation busbar.
Accordingly, it is possible to expect downsizing around the power module, and it is possible to provide an insulating bus bar with higher withstand voltage suitable for an element required as a SiC device to be developed in the future.

(Insulation bus bar manufacturing method)
Next, an aspect of the method for manufacturing an insulating bus bar of the present invention will be described with reference to the drawings.
2-5 is sectional drawing which shows a certain aspect of the manufacturing method of the insulation bus bar of this invention.
The method for manufacturing an insulating bus bar according to the present embodiment includes a “laminated body manufacturing step”, a “penetrating terminal installation step”, and a “resin impregnation step”.

<Laminated body production process>
[Conductor drilling]
First, through holes 11A and 11B for loosely fitting the through terminals 40 and through holes 12A and 12B for joining the through terminals 40 to the mesh conductors 10A and 10B are provided. The through holes 11A and 11B are set such that the distance between the inner peripheral surface and the through terminal 40 is equal to or greater than the above-described separation distance d corresponding to the maximum potential difference generated in the mesh conductors 10A and 10B.

[Insulation sheet drilling]
Next, in the same manner as the conductor drilling process, the mesh-shaped insulating sheet 20 is drilled so as to provide a certain gap, thereby providing the through holes 21. Here, in order to form the gap so as to cover the through holes 11A and 11B of the conductors 10A and 10B, the distance between the inner peripheral surface of the through hole 21 and the through terminal 40 may be narrower than the above-described separation distance d. preferable.

[Production of laminate]
As shown in FIG. 2, the perforated mesh-shaped conductor 10 and the perforated mesh-shaped insulating sheet 20 are laminated so that the positions of the respective through holes 11 and 12 coincide with the thickness direction. Thus, the laminated body 30 is manufactured. The laminated body 30 is produced by, for example, laminating the insulating sheet 20, the conductor 10A, the insulating sheet 20, the conductor 10B, and the insulating sheet 20 in the thickness direction in this order.

<Penetration terminal installation process>
The through terminal installation step is a step of joining the through terminal 40 so as to penetrate the stacked body 30. Specifically, as shown in FIG. 3, when manufacturing the laminated body 30, “conductor drilling” and “insulating sheet drilling” that are aligned so as to penetrate the multilayer body 30 in the thickness direction. This is a step of installing the through terminals 40 in the through holes 11 and 12 provided in the “processing”. The aligned through terminals 40 are joined to the mesh conductors 10A and 10B or the insulating sheet 20 by brazing or soldering.

Through this through terminal installation process, as shown in FIG. 3, the mesh-like conductor 10A has a through hole 11A provided with a gap of a separation distance d with respect to a through terminal 40A and another through terminal 40B. Thus, a through hole 11B joined by brazing or soldering is formed. On the other hand, the mesh-like conductor 10B is provided with a through hole 11B joined by brazing or soldering to a certain through terminal 40A and a gap with a separation distance d from the other through terminal 40B. A through hole 11A is formed.
In addition, a plurality of through holes 21 having the same dimensions corresponding to the cross-sectional shape of the through terminals 40 are formed in the mesh-like insulating sheet 20. The separation distances of the through holes 21 with respect to the through terminals 40 are preferably smaller than the separation distance d in order to cover the inner peripheral ends of the through holes 11 and 12 of the mesh conductor 10.

<Resin impregnation step>
Next, as shown in FIG. 4, the laminate 30 on which the through terminals 40 are installed is fixed to a mold 81. Specifically, the laminated body 30 is fixed so that one end and the other end in the penetrating direction of the through terminal 40 are sandwiched between the inner surfaces 81a and 81a of the pair of molds 81, respectively.
The mold 81 is firmly fixed by mold fixing jigs 82 and 83 that are fastened together so that a molten insulating resin 50 described later does not leak from between the through terminal 40 and the mold 81. The At this time, it is preferable that a sealing agent (for example, vacuum grease) or a release agent is applied to the mold 81.
The material of the mold 81 is not particularly limited as long as it does not affect the impregnation of the insulating resin 50 into the conductor 10 and the insulating sheet 20 in the resin impregnation step of the present embodiment, and may be made of resin or metal. preferable.

  Thereafter, the insulating resin 50 is evacuated to impregnate the mesh-like conductor 10 and the mesh-like insulating sheet 20 with the insulating resin 50, respectively, and integrally formed with the through terminals 40. Specifically, as shown in FIG. 5, an opening 81 </ b> A, 81 </ b> B is provided at both ends in the longitudinal direction of a mold 81 in which the stacked body 30 is fixed. Then, the inside of the mold 81 to which the laminated body 30 is fixed is decompressed from one opening 81A by a vacuum pump or the like, and the insulating resin 50A is sucked from the other opening 81B, and the mesh conductor 10 Then, impregnation with the mesh-like insulating sheet 20 is performed. At this time, the melted insulating resin 50A also flows into the region formed by the through hole 21 and the through terminal 40 (the region indicated by the separation distance d) and hardens, thereby being sealed with the insulating resin 50.

Thereafter, curing is performed according to the curing conditions of the insulating resin 50. If the curing process is performed under normal pressure or pressurized conditions rather than reduced pressure conditions, voids are less likely to remain in the insulating resin 50, and an improvement in dielectric strength can be expected.
Here, when a filler is added to the insulating resin (for example, epoxy resin) impregnated in the conductor 10 and the insulating sheet 20, the mesh (mesh) interval between the conductor 10 and the insulating sheet 20 is at least from the diameter of the filler. It needs to be twice or more. By defining the mesh (mesh) interval between the conductor 10 and the insulating sheet 20 in this way, voids do not remain in the laminated body 30 in this step, and the insulating resin 50 is sufficiently distributed in the laminated body 30.

Further, the through terminal 40 needs to expose the conductor portion in order to maintain the conduction with the connection screw 201 of the semiconductor element 200 shown in FIG. 9, but is fastened by a bolt and nut such as the mold fixing jigs 82 and 83. In addition to this, the mold 81 may be pressed, or the conductor portion of the through terminal 40 may be exposed by machining after the resin impregnation.
Further, the impregnation of the insulating resin 50 into the conductor 10 and the insulating sheet 20 in this step is not limited to the above-described evacuation due to the viscosity of the molten insulating resin 50, and may be extruded by pressing from the other opening 81 </ b> B. Pulling and pressure extrusion may be used in combination.
According to the above steps, voids are unlikely to be formed in the insulating resin 50 by alternately impregnating the insulating conductor 50 by vacuuming the mesh conductor 10 and the mesh insulating sheet 20 that are alternately stacked. There is an effect.

In addition, since the insulating bus bar manufactured in the present embodiment does not have a bonding interface or an adhesive layer around the through terminal 40, a weak point of insulation (“A” in FIG. 9) is not formed.
In addition, since the insulating bus bar manufactured in the present embodiment has a laminated structure of a conductor and an insulator and is not an adhesive structure between the plate-like body and the plate-like body, even if bending or stress is applied to the insulating bus bar, Peeling from the insulator hardly occurs.
Further, the insulating bus bar manufactured in this embodiment reduces the manufacturing cost because the mesh conductor 10 and the mesh insulating sheet 20 are integrated with the insulating resin 50 without providing an adhesive layer. be able to.

Furthermore, the insulating bus bar manufactured in the present embodiment provides a heat-resistant insulating bus bar by using a thermosetting resin for the insulating resin 50, rather than using a thermoplastic resin as in Patent Documents 1 to 4. be able to.
In addition, the insulation bus bar manufactured in the present embodiment has a fixed inductance between the mesh conductors by the mesh insulation sheet, has a low inductance compared to a general bus bar, and is an integrated structure. It also has the characteristics of the conventional insulation bus bar that it is easy.
Accordingly, it is possible to expect a reduction in size around the power module, and it is possible to provide a method for manufacturing an insulated bus bar having a higher withstand voltage suitable for an element required as a SiC device that will be developed in the future.

(Other embodiments)
FIG. 6 is a cross-sectional view showing the configuration of another embodiment of the insulated bus bar of the present invention. Moreover, FIG. 7 is sectional drawing which shows other embodiment of the manufacturing method of the insulation bus bar of this invention. The insulating bus bar and the manufacturing method thereof according to the present embodiment are different from the above-described embodiment only in the configuration of the mold used in the resin impregnation step and the creeping distance securing portion formed thereby. The same reference numerals are assigned to the same or similar members in FIG.
As shown in FIG. 6, as another embodiment of the insulating bus bar, a creeping distance securing portion 60 that is integrated with the insulating resin 50 and has a plurality of protrusions protruding in the thickness direction may be provided. As shown in FIG. 7, the creeping distance securing portion 60 can be manufactured by using a mold 81 having a plurality of concave portions 81 b formed on the inner surface.

Here, many conventional semiconductor elements have been proposed in which the creeping distance D (see FIG. 9) is increased to improve the insulation performance by providing an uneven shape between two external lead-out terminals. On the other hand, since the conventional laminated bus bar is manufactured by press-bonding a conductor and an insulator by pressing, the surface of the insulating bus bar has a substantially flat shape, and the creepage distance D ₁ (D ₁ <D) is short. In some cases, sufficient insulation performance could not be exhibited. Therefore, in order to improve the mutual insulation performance, a pleat groove structure or the like molded so as to increase the creepage distance is provided on the surface of the insulation bus bar. However, as a result of installing such a pleated groove structure as a separate member on the surface of the insulating bus bar, mechanical and electrical problems (peeling, partial discharge, dielectric breakdown) newly arise due to the installation. There was a thing.

With respect to such a problem, mechanical and electrical problems can be solved by forming the creeping distance securing portion 60 having a fluted groove structure on the surface of the insulating bus bar integrally with the insulating resin 50 as in this embodiment. A long creepage distance D ₂ (D ₂ > D ₁ (see FIG. 9)) can be ensured without occurring.
Moreover, since the shape of the creeping distance securing portion 60 and the laminated body 30 has a degree of freedom by changing the shape of the recess 81b of the mold 81, it is possible to secure a creeping distance that is difficult to achieve with a conventional insulating bus bar. For example, by using a mold having a partially curved shape, as shown in FIG. 8, an insulating bus bar having a curved portion 70 curved between the through terminals 40A and 40B of the laminate 30 can be produced. And a longer creepage distance D ₃ (D ₃ > D ₁ (see FIG. 9)) can be secured.
As mentioned above, although embodiment of this invention has been described, this invention is not limited to this, A various change and improvement can be performed.

DESCRIPTION OF SYMBOLS 10 ... Mesh-like conductor 20 ... Mesh-like insulating sheet 30 ... Laminated body 40 ... Penetration terminal 50 ... Insulating resin 60 ... Creeping distance securing part 81 ... Impregnation casting Mold 82... Mold fixing jig 83... Mold fixing jig 84.

Claims (6)

A laminate in which a mesh-like conductor and a mesh-like insulating sheet are laminated, and a through terminal joined so as to penetrate the laminate,
An insulating bus bar, wherein the mesh-shaped conductor, the mesh-shaped insulating sheet, and the through terminal are integrally formed of an insulating resin impregnated in each.   2. The insulating bus bar according to claim 1, wherein a material of the mesh-like insulating sheet is polypropylene, polyethylene terephthalate, insulating paper impregnated with the insulating resin, or glass fiber.   The insulating bus bar according to claim 1, further comprising a creeping distance securing portion integrated with the insulating resin. A laminate production step of producing a laminate by laminating a mesh-like conductor and a mesh-like insulating sheet;
A through terminal installation step of joining through terminals so as to penetrate the laminate; and
The laminated body in which the through terminals are installed is fixed to a mold, and an insulating resin is evacuated to impregnate the mesh-like conductor and the mesh-like insulating sheet with the insulating resin, respectively. And a resin impregnation step integrally molded with the through terminal.   The method of manufacturing an insulating bus bar according to claim 4, wherein a material of the mesh-like insulating sheet is polypropylene, polyethylene terephthalate, insulating paper impregnated with the insulating resin, or glass fiber.   6. The method of manufacturing an insulating bus bar according to claim 4, wherein the resin impregnation step forms a creeping distance securing portion integrated with the insulating resin.

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