Electrical equipment

Abstract

Suppress migration. [Solution] The electrical device 1 comprises a multilayer wiring board 2 in which a plurality of conductor layers 21 stacked in a first direction and an insulating layer 22 made of a glass fiber substrate impregnated with resin are alternately stacked, and a metal member extending in a first direction. The end of the multilayer wiring board 2 facing the metal member is covered with a metal film 24, and the metal film 24 is electrically insulated from the plurality of conductor layers 21 and also electrically insulated from the metal member.

Description

Technical Field

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[0001] The present invention relates to an electrical device.

Background Art

[0002] Devices handling electricity are required to meet various technical requirements. Patent Document 1 discloses a module component including a circuit board having an upper surface, a lower surface, and side surfaces, components mounted on the upper surface of the circuit board, a sealing portion provided on the upper surface of the circuit board and sealing the components and having an upper surface, a ground pattern provided on an outer peripheral portion of the lower surface of the circuit board, a top surface portion covering the upper surface of the sealing portion, a side surface portion extending from the top surface portion and covering the side surfaces of the circuit board, and a bottom surface portion extending from the side surface portion, provided on the ground pattern, and having a thickness that decreases as it moves away from the side surface portion, and a metal film including the same. <00,00010>

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the invention described in Patent Document 1, there is room for improvement from the viewpoint of suppressing migration.

Means for Solving the Problems

[0005] An electrical device according to a first aspect of the present invention comprises a multilayer wiring board in which a plurality of conductor layers stacked in a first direction and an insulating layer made by impregnating a glass fiber substrate with resin are alternately stacked, and a metal member extending in the first direction, wherein the end of the multilayer wiring board facing the metal member is covered with a metal film, and the metal film is electrically insulated from the plurality of conductor layers and also electrically insulated from the metal member. [Effects of the Invention]

[0006] According to the present invention, migration can be suppressed. [Brief explanation of the drawing]

[0007] [Figure 1] Cross-sectional view of an electrical device [Figure 2] Cross-sectional view of the electrical device in the first comparative example. [Figure 3] Cross-sectional view of the electrical device in the second comparative example. [Figure 4] Cross-sectional view of an electrical device in a modified example. [Modes for carrying out the invention]

[0008] —First Embodiment— The first embodiment of the electrical device will be described below with reference to Figures 1 to 3.

[0009] Figure 1 is a cross-sectional view of the electrical device 1. The electrical device 1 comprises a multilayer wiring board 2, a cooler 3, and a metal housing 4. The metal housing 4 has a roughly C-shaped cross-section and houses the multilayer wiring board 2 and the cooler 3. Specifically, the metal housing 4 includes the left side 41, the bottom 42, and the right side 43. However, "left" for the left side 41 and "right" for the right side 43 are names used for convenience. The left side 41 and the right side 43 extend in the vertical direction shown in the figure (hereinafter referred to as the "first direction"), and the bottom 42 extends in the horizontal direction shown in the figure (hereinafter referred to as the "second direction").

[0010] The cooler 3 and the metal housing 4 are made of metal, and both can be called "metal components". The cooler 3 comprises an upper cooler 31, a lower cooler 32, and a water channel fixing member 33. The water channel fixing member 33 extends in a first direction, which is the vertical direction shown in the figure, and connects the upper cooler 31 and the lower cooler 32. Solder resist 51 is placed on the surface of the multilayer wiring board 2. The solder resist 51 at the bottom of the multilayer wiring board 2 is in contact with the lower cooler 32 via a heat dissipation sheet 52. The cooler 3 is fixed to the metal housing 4. The multilayer wiring board 2 is made by alternately laminating a plurality of conductor layers 21 that are stacked in a first direction and insulating layers 22 made by impregnating a glass fiber substrate with resin. However, different insulating layers 22 may be in contact with each other, so the conductor layers 21 and insulating layers 22 are not alternately laminated at all locations.

[0011] The multilayer wiring board 2 has through holes 23 that penetrate one or more insulating layers 22 in a first direction. The through holes 23 are a general term for general through holes 23A for connecting conductor layers 21 in different layers, and the through holes 23B that are not intended for connecting conductor layers 21. The through holes 23B are provided for the purpose of creating space for a metal member, i.e., a water channel fixing member 33, that penetrates the multilayer wiring board 2 in a first direction. Interlayer connection portions 21A for connecting conductor layers 21 are arranged on the side surface of the general through holes 23A. The side surface and edge of the through holes 23B are covered with a metal coating 24, which will be described later.

[0012] The edges of the multilayer wiring board 2 are covered with a metal coating 24. In Figure 1, the metal coating 24 is shown by dot hatching. The edges of the multilayer wiring board 2 include not only the position facing the left side surface 41 of the housing at the left end of the figure and the position facing the right side surface 43 of the housing at the right end of the figure, but also the left and right positions facing the water channel fixing material 33. Furthermore, the edges of the multilayer wiring board 2 also include the edges of the through holes 23 and the sides of the through holes 23. The metal coating 24 acts as a sealant, so to speak, to prevent moisture from entering the insulating layer 22.

[0013] There is a physical gap, so-called an air gap, between the metal film 24 and the metal member, specifically between the metal film 24 and the left housing surface 41, the right housing surface 43, and the water channel fixing member 33, and the two are not in close contact. Since air is insulating, it can be said that the space between the metal film 24 and the metal member is insulated by the air gap. Also, since air has a large insulation resistance value, the resistance value between the metal film 24 and the metal member is larger than the insulation resistance value between the metal film 24 and the plurality of conductor layers 21. Specifically, let the smallest resistance value between the metal film 24 and the metal member be Ra, and the smallest resistance value between the metal film 24 and the conductor layer 21 be Rb. In this case, the relationship Ra > Rb holds, and it is difficult for current to flow between the metal film 24 and the metal member.

[0014] Furthermore, although the multilayer wiring board 2 which is an insulator has a relatively low relative permittivity, its permittivity is larger than that of air. In the present embodiment, the capacitance between the metal film 24 and the metal member is smaller than the capacitance between the metal film 24 and the plurality of conductor layers 21. Specifically, let the capacitance between the metal film 24 and the metal member be Ca, and the capacitance between the metal film 24 and the conductor layer 21 be Cb. In this case, the relationship Ca < Cb holds, and it is difficult for current to flow between the metal film 24 and the metal member.

[0015] (Comparative Example 1) FIG. 2 is a cross-sectional view of a first comparative example electrical device 1Z1 which is a first comparative example. The difference between the first comparative example electrical device 1Z1 and the electrical device 1 is the presence or absence of the metal film 24. The first comparative example electrical device 1Z1 does not have the metal film 24 at any of the positions facing the left housing surface 41 at the left end shown in the figure, which is the end of the multilayer wiring board 2, the position facing the right housing surface 43 at the right end shown in the figure, and the left and right positions facing the water channel fixing member 33. At these positions, in addition to the electric field concentration at the conductor end, the surface is rough due to the drilling process and is likely to absorb moisture from the glass fiber and resin interface. Therefore, migration may occur due to the infiltrated moisture as indicated by reference numeral 901. On the other hand, in the electrical device 1 in the present embodiment, the end of the multilayer wiring board 2 is covered with the metal film 24, so the intrusion of moisture is prevented and migration is suppressed.

[0016] (Comparative Example 2) FIG. 3 is a cross-sectional view of a second comparative example electrical device 1Z2 which is a second comparative example. The difference between the second comparative example electrical device 1Z2 and the electrical device 1 is the distance between the metal film 24 and the metal member. When the water channel fixing member 33 and the metal film 24 are in an electrically connected state, a high voltage may be applied between the conductor layer 21 and the metal film 24, and migration may occur between the metal film 24 and the conductor layer 21 as indicated by reference numeral 902. On the other hand, in the electrical device 1 according to the present embodiment, an air gap is provided between the metal film 24 and the metal member, so that application of voltage is prevented and migration is suppressed.

[0017] According to the first embodiment described above, the following operational effects can be obtained. (1) The electrical device 1 includes a multilayer wiring board 2 in which a plurality of conductor layers 21 laminated in a first direction which is the vertical direction in the drawing and an insulating layer 22 formed by impregnating a glass fiber base material with resin are alternately laminated, and metal members extending in the first direction, that is, a cooler 3 and a metal housing 4. The ends of the multilayer wiring board 2 facing the water channel fixing member 33, the left side surface 41 of the housing, and the right side surface 43 of the housing are covered with a metal film 24. The metal film 24 is electrically insulated from the plurality of conductor layers 21 and is also electrically insulated from the water channel fixing member 33, the left side surface 41 of the housing, and the right side surface 43 of the housing. Therefore, it is possible to prevent moisture absorption from the interface between the glass fiber and the resin constituting the insulating layer 22, reduce the potential between the metal film 24 and the conductor layer 21, and prevent migration.

[0018] (2) The left side surface 41 of the housing and the right side surface 43 of the housing are part of a metal housing 4 that houses the multilayer wiring board 2.

[0019] (3) The multilayer wiring board 2 has a through hole 23B of the present case penetrating in the first direction. The water channel fixing member 33 which is a metal member is inserted into the through hole 23B of the present case. The ends of the multilayer wiring board 2 covered with the metal film 24 are the edge and the side surface of the through hole 23B of the present case.

[0020] (4) The metal film 24 and the metal member are electrically insulated via an air gap.

[0021] (5) The resistance value between the metal film 24 and the metal member is larger than the insulation resistance value between the metal film 24 and the plurality of conductor layers 21. Therefore, the voltage generated between the metal film 24 and the metal member can be reduced, and migration can be suppressed.

[0022] (6) The capacitance between the metal film 24 and the metal member is smaller than the capacitance between the metal film 24 and the plurality of conductor layers 21. Therefore, the voltage generated between the metal film 24 and the metal member can be reduced, and migration can be suppressed.

[0023] (Modification 1) It is not an essential configuration that the multilayer wiring board 2 has the general through hole 23A and the through hole 23B of the present case. It may have only one of them, or may not have both. The electric device 1 includes the cooler 3 and the metal housing 4 which are metal members. However, the electric device 1 may include at least one of the cooler 3 and the metal housing 4. When the electric device 1 does not include the cooler 3, the multilayer wiring board 2 does not include the through hole 23B of the present case, and the metal film 24 included in the multilayer wiring board 2 is formed at a position facing the left side surface 41 of the housing and a position facing the right side surface 43 of the housing. When the electric device 1 does not include the metal housing 4, for example, when using a non-metallic housing or when not using the housing itself, the metal film 24 included in the multilayer wiring board 2 is formed at a position facing the water channel fixing member 33 in the through hole 23B of the present case.

[0024] (Modification 2) FIG. 4 is a cross-sectional view of the electric device 1 in Modification 2. In the first embodiment described above, the metal film 24 and the metal member are electrically insulated by an air gap. However, an insulating resin 29 may be disposed between the metal film 24 and the metal member. By disposing the insulating resin 29, the metal film 24 and the metal member can be stably insulated.

[0025] According to this modification, the following effects can be obtained. (7) The metal film 24 and the metal member are electrically insulated from each other via the insulating resin 29. Therefore, the metal film 24 and the metal member can be stably insulated, and migration is suppressed. In this modified example, the insulating resin 29 is disposed at all four locations between the metal film 24 and the metal member. However, it is not an essential configuration to dispose the insulating resin 29 at all four locations, and the insulating resin 29 may be disposed at only some locations.

[0026] (Modified Example 3) In the above-described first embodiment, an air gap existed between the metal film 24 and the metal member. However, the metal film 24 and the metal member may be in close contact with each other via an insulating resin. Further, when the smallest resistance value between the metal film 24 and the metal member is Ra and the smallest resistance value between the metal film 24 and the conductor layer 21 is Rb, the relationship Ra > Rb holds. However, Ra < Rb may also be possible. Furthermore, when the capacitance between the metal film 24 and the metal member is Ca and the capacitance between the metal film 24 and the conductor layer 21 is Cb, the relationship Ca < Cb holds. However, Ca > Cb may also be possible.

[0027] The above-described embodiments and modified examples may be combined with each other. Although various embodiments and modified examples have been described above, the present invention is not limited to these contents. Other aspects conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention.

Explanation of Reference Numerals

[0028] 1: Electric device 2: Multilayer wiring board 3: Cooler 4: Metal housing 21: Conductor layer 21A: Interlayer connection portion 22: Insulating layer 23B: Through-hole of the present case 24: Metal film 29: Insulating resin 33: Waterway fixing material 41: Left side surface of the housing 43: Right side surface of the housing

Claims

1. A multilayer wiring board in which multiple conductive layers stacked in a first direction and insulating layers made by impregnating a glass fiber substrate with resin are alternately stacked, A metal member extending in the first direction, The end of the multilayer wiring board facing the metal member is covered with a metal coating. An electrical device wherein the metal coating is electrically insulated from the plurality of conductor layers and also electrically insulated from the metal member.

2. In the electrical device described in claim 1, An electrical device in which the metal component is a metal housing that houses the multilayer wiring board.

3. In the electrical device described in claim 1, The multilayer wiring board has through holes penetrating in the first direction, The aforementioned metal member is inserted into the through hole. An electrical device in which the end portion is the edge of the through hole and the side of the through hole.

4. In the electrical device described in claim 1, An electrical device in which the metal coating and the metal member are electrically insulated from each other via an air gap or insulating resin.

5. In the electrical device described in claim 1, An electrical device wherein the resistance value between the metal coating and the metal member is greater than the insulation resistance value between the metal coating and the plurality of conductor layers.

6. In the electrical device described in claim 1, An electrical device wherein the capacitance between the metal coating and the metal member is smaller than the capacitance between the metal coating and the plurality of conductive layers.

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