Power conversion device and method for manufacturing printed circuit board for power conversion device

Abstract

This power conversion device includes a printed circuit board on which an electrical component is mounted. An insulating resin material is fixed on a surface of the printed circuit board in a prescribed sealing range that includes an electrical connection between the printed circuit board and a terminal part of the electrical component. The resin material includes a photopolymerization initiator that initiates polymerization when irradiated with light.

Description

Power converter and method for manufacturing printed circuit board for power converter

[0001] The present invention relates to a power converter and a method for manufacturing a printed circuit board used therein.

[0002] Power conversion devices such as inverters and DC-DC converters contain many electrical components to which high voltages are applied, such as semiconductor elements that perform power conversion through switching operations. When mounting electrical components on a printed circuit board, a creepage distance corresponding to the voltage must be secured between the electrodes of each component. However, electrodes to which high voltages are applied require a longer creepage distance. This makes it difficult to densely mount electrical components on the printed circuit board of a power conversion device, resulting in an increase in size.

[0003] As a solution to the above problem, a method is known in which the required insulation creepage distance is reduced by coating an insulating resin over an area including the area between electrodes on a printed circuit board to which a high voltage is applied. For example, Patent Document 1 describes a method in which a liquid epoxy resin composition is poured into a mold in which electrical components are placed, and the epoxy resin composition is semi-cured by irradiating it with light and heating, and then the mold is opened to completely cure the epoxy resin composition.

[0004] Japanese Patent Application Publication No. 2017-228611

[0005] In the method of Patent Document 1, in order to coat a predetermined area with epoxy resin, multiple steps must be performed: a step of installing a mold, a step of semi-curing the epoxy resin, a step of opening the mold, and a step of completely curing the epoxy resin, which requires a lot of time and effort, resulting in the problem of increased manufacturing costs.Furthermore, while it has become important in recent years to reduce the amount of energy used during manufacturing as a measure against global warming, the method of Patent Document 1 also has the problem of energy being consumed for heating in the step of semi-curing the epoxy resin.

[0006] The present invention has been made in view of the above-mentioned problems, and a main object of the present invention is to realize a power conversion device in which electrical components are densely mounted, at low cost and with low energy consumption.

[0007] A power conversion device according to the present invention includes a printed circuit board on which electrical components are mounted, and an insulating resin material is fixed to a surface of the printed circuit board in a predetermined sealing area including terminals of the electrical components and electrical connections between the printed circuit board, the resin material containing a photopolymerization initiator that initiates polymerization when irradiated with light. A method for manufacturing a printed circuit board for a power conversion device according to the present invention is a method for manufacturing a printed circuit board for a power conversion device having electrical components mounted thereon and being included in a power conversion device, the method comprising: a first step of supplying an insulating resin material that is fluid before curing and that hardens when exposed to light from a predetermined supply position on the surface of the printed circuit board while irradiating a predetermined irradiation area set so as to surround the electrical connections between the terminals of the electrical components and the printed circuit board with light; and a second step of curing an uncured portion of the resin material that has been selectively hardened in the portion corresponding to the irradiation area in the first step.

[0008] According to the present invention, a power conversion device in which electrical components are densely mounted can be realized at low cost and with low energy consumption.

[0009] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed.

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0011] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0012] FIG. 1 is a perspective view of the exterior of a power conversion device according to one embodiment of the present invention. The power conversion device 100 shown in FIG. 1 is, for example, an inverter, and is configured by covering an opening of a housing 101 with a lid 102. A printed circuit board 1 on which electrical components such as semiconductor elements that perform switching operations are mounted is installed inside the housing 101. In addition to the printed circuit board 1, various other components such as a control circuit, an EMC filter, and a smoothing capacitor are also installed inside the housing 101, but these are not shown in FIG. 1. An AC connector 103 and a DC connector 104 protrude from the housing 101, and a signal connector 105 is attached to the lid 102.

[0013] 2A and 2B are diagrams showing the structure of a printed circuit board provided in a power conversion device according to an embodiment of the present invention, in which (a) is a plan view of the printed circuit board 1 and (b) is a cross-sectional view of the printed circuit board 1.

[0014] The printed circuit board 1 has a plurality of penetration regions 2 that penetrate between the front and back surfaces. The penetration regions 2 are, for example, through-holes. The printed circuit board 1 also has a plurality of electrical components 3, such as semiconductor elements. Each electrical component 3 has a terminal portion 4 to which a high voltage is applied, and the terminal portion 4 is connected by solder or the like to a wiring pattern 5 provided on the printed circuit board 1. This electrically connects each electrical component 3 to the printed circuit board 1.

[0015] An insulating resin material 10 is fixed in a cured state to the surface of the printed circuit board 1 in a predetermined sealing area that includes the electrical connection between the terminal portions 4 of each electrical component 3 and the printed circuit board 1. This resin material 10 is a photocurable resin and contains a photopolymerization initiator that initiates polymerization when irradiated with light. The method for curing the resin material 10 during the manufacture of the printed circuit board 1 will be described in detail below.

[0016] Furthermore, the resin material 10 may contain a humidity polymerization initiator that initiates polymerization in response to humidity, so that even if a portion of the resin material 10 is not completely cured due to insufficient light irradiation, it can be completely cured over time due to the humidity in the atmosphere.

[0017] In the printed circuit board 1, the side surfaces of the outer edge portion 11 of the resin material 10 and the bottom surface 12 of the resin material 10 filled in the through region 2 are uneven and irregular. In other words, these surfaces have an outwardly convex shape. This surface shape is formed during the manufacture of the printed circuit board 1 by supplying the fluid uncured resin material 10 onto the surface of the printed circuit board 1 on which the electrical components 3 are mounted, while irradiating a predetermined irradiation position with light, thereby directly curing the resin material 10 without using a mold or the like.

[0018] FIG. 3 is a diagram illustrating a method for manufacturing a printed circuit board according to an embodiment of the present invention. FIG. 3 illustrates a process for sealing electrical connections between terminals 4 of electrical components 3 mounted on the printed circuit board 1 and the printed circuit board 1 with a resin material 10, which is one of the manufacturing steps for the printed circuit board 1. In this process, as shown in FIG. 3 , a plurality of light sources 20 are disposed on the front (upper) side of the printed circuit board 1, each of which emits light for curing the resin material 10, and a mask 22 is disposed to block the light emitted from the light sources 20. Specifically, the mask 22 is disposed on the front surface of the printed circuit board 1 in accordance with a predetermined sealing area so as to cover all electrical connections between the terminals 4 of the electrical components 3 to be sealed and the printed circuit board 1. Furthermore, each light source 20 is disposed so as to surround the mask 22. This sets the light irradiation area of ​​the light source 20 so as to surround the electrical connections between the terminals 4 of the electrical components 3 and the printed circuit board 1.

[0019] A nozzle 23 for dropping and supplying the uncured resin material 10 is disposed in the sealed area covered by the mask 22. The position of this nozzle 23 determines the position on the surface of the printed circuit board 1 to which the uncured resin material 10 is supplied. Because the uncured resin material 10 has low viscosity and is fluid, it gradually spreads from the supply position (the position of the nozzle 23) along the surface of the printed circuit board 1.

[0020] Furthermore, a plurality of light sources 21 that each emit light with the same wavelength as light source 20 are also arranged on the rear surface (bottom side) of printed circuit board 1. Each light source 21 is arranged at a position corresponding to a respective one of the plurality of through-hole regions 2 provided on printed circuit board 1. This sets the range of light irradiation by light source 21 from the rear surface side of printed circuit board 1 toward each through-hole region 2.

[0021] 3, using the configuration described above, uncured resin material 10 is supplied from a predetermined supply position by nozzle 23 onto the surface of printed circuit board 1 while light is irradiated onto the respective irradiation areas by light sources 20 and 21. This allows resin material 10 to spread over the entire area covered by mask 22, while selectively curing resin material 10 by light irradiation at outer edge 11 and bottom surface 12 of penetration region 2. As a result, a container for filling uncured resin material 10 is formed on the surface of printed circuit board 1, making it possible to prevent resin material 10 from spilling out of the predetermined sealing area.

[0022] In the printed circuit board 1 manufactured by carrying out the process of Fig. 3 , as described above, the side surfaces of the outer edge portion 11 of the resin material 10 and the bottom surface 12 of the resin material 10 filled in the penetration region 2 are uneven and irregular, having outwardly convex shapes. On the other hand, if the sealing range of the resin material 10 is determined using a mold or the like instead of the process of Fig. 3 , the side surfaces of the outer edge portion 11 and the bottom surface 12 of the penetration region 2 are smooth surfaces without having outwardly convex shapes. In other words, it can be confirmed that the process of Fig. 3 has been carried out by the fact that the side surfaces of the outer edge portion 11 of the resin material 10 and the bottom surface 12 of the resin material 10 filled in the penetration region 2 have outwardly convex shapes in the printed circuit board 1.

[0023] 3 , the low-viscosity resin material 10 remains uncured in the areas not irradiated with light. Therefore, after this step, the mask 22 is removed, and the entire area of ​​the printed circuit board 1 filled with the resin material 10 is irradiated with light to cure the uncured areas of the resin material 10. This cures the entire resin material 10, allowing the required area of ​​the printed circuit board 1 to be sealed with the resin material 10.

[0024] 3 and the subsequent steps, it is preferable to further perform a step of degassing the resin material 10. The degassing of the resin material 10 can be performed, for example, by vacuum degassing. In this way, it is possible to degas the air bubbles contained in the uncured resin material 10 and reduce voids in the cured resin material 10.

[0025] 3, the light sources 20 and 21 may each be a single light source, or multiple light sources 20 and 21 may be used to irradiate the required amount of light to the required locations. The position at which the resin material 10 is supplied from the nozzle 23 is preferably a position that avoids the light irradiation range of the light sources 20 and 21 and the vicinity of the penetration region 2, and is preferably near the terminal portion 4 of the electrical component 3 to which a high voltage is applied. Furthermore, multiple nozzles 23 may be used depending on the required filling speed. The method of supplying the resin material 10 from the nozzle 23 may be determined depending on the situation, and may be a drip type, a spray type, or the like.

[0026] 3, after the outer edge 11 and bottom surface 12 of the resin material 10 are cured, the uncured resin material 10 may be replaced with another resin material having a different composition. In this case, the resin material 10 in the manufactured printed circuit board 1 is positioned closer to the outer edge 11 of the sealing area than the replaced resin material. In this way, the properties required to seal the terminals 4 of each electrical component 3 may be obtained.

[0027] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0028] (1) The power conversion device 100 includes a printed circuit board 1 on which electrical components 3 are mounted. An insulating resin material 10 is fixed to the surface of the printed circuit board 1 in a predetermined sealing area that includes the electrical connection between the terminals 4 of the electrical components 3 and the printed circuit board 1. The resin material 10 contains a photopolymerization initiator that initiates polymerization when irradiated with light. This configuration allows the resin material 10 to be filled to any desired height in a sealing area that is arbitrarily set on the surface of the printed circuit board 1 without using a mold or the like, and the resin material 10 can be cured within the sealing area, thereby shortening the insulation distance at the terminals 4 of the electrical components 3 to which a high voltage is applied. Furthermore, a heating process for curing the resin material 10 is not required, eliminating the need for power consumption for heating. Therefore, a power conversion device 100 in which electrical components 3 are densely packed can be realized at low cost and with low energy consumption.

[0029] (2) A method for manufacturing a printed circuit board 1 mounted with electrical components 3 and provided in a power conversion device 100 includes the steps of: supplying insulating resin material 10, which is fluid before curing and hardens when exposed to light, from a predetermined supply position set on the surface of the printed circuit board 1 while irradiating a predetermined irradiation area set so as to surround the electrical connection between terminal portions 4 of the electrical components 3 and the printed circuit board 1 with light (the step shown in FIG. 3 ); and curing the uncured portions of resin material 10, which has been selectively hardened in the portions corresponding to the irradiation area in this step. This allows a printed circuit board 1 for a power conversion device 100, having a structure as shown in FIG. 2 and having electrical components 3 densely mounted thereon, to be realized at low cost and with low energy consumption.

[0030] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to replace part of the configuration of one embodiment with the configuration of another embodiment, or to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of each embodiment with other configurations.

[0031] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0032] 1: printed circuit board, 2: penetration area, 3: electrical component, 4: terminal portion, 5: wiring pattern, 10: resin material, 11: outer edge portion, 12: bottom surface, 20, 21: light source, 22: mask, 23: nozzle, 100: power conversion device

Claims

1. A power conversion device comprising a printed circuit board on which electrical components are mounted, wherein an insulating resin material is fixed to the surface of the printed circuit board in a predetermined sealing area including the electrical connection between the terminals of the electrical components and the printed circuit board, and the resin material contains a photopolymerization initiator that initiates polymerization when irradiated with light.

2. A power conversion device according to claim 1, wherein the resin material contains a humidity polymerization initiator that initiates polymerization in response to humidity.

3. A power converter according to claim 1, wherein the outer edge side surface of the resin material has an outwardly convex shape.

4. A power conversion device according to claim 1, wherein the printed circuit board has a through-hole region that penetrates between the front and back surfaces, and the bottom surface of the resin material filled in the through-hole region has an outwardly convex shape.

5. A power conversion device according to claim 1, wherein the resin material comprises a first resin material containing the photopolymerization initiator and a second resin material having a different composition from the first resin material, and the first resin material is disposed closer to the outer edge of the sealing area than the second resin material.

6. A method for manufacturing a printed circuit board for a power conversion device that has electrical components mounted thereon, the method comprising: a first step of supplying an insulating resin material that is fluid before hardening and hardens when exposed to light from a predetermined supply position set on the surface of the printed circuit board while irradiating light onto a predetermined irradiation range set so as to surround the electrical connection between the terminal portion of the electrical component and the printed circuit board; and a second step of hardening an unhardened portion of the resin material that has been selectively hardened in the portion corresponding to the irradiation range in the first step.

7. A method for manufacturing a printed circuit board for a power converter according to claim 6, wherein the printed circuit board has a penetration region that penetrates between the front and back surfaces, and in the first step, the light is also irradiated onto the penetration region from the back surface side of the printed circuit board.

8. A method for manufacturing a printed circuit board for a power converter according to claim 7, wherein the supply position is a position that avoids the vicinity of the irradiation range and the penetration area.

9. The method for manufacturing a printed circuit board for a power converter according to claim 6, further comprising a step of degassing the resin material between the first step and the second step.

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