JP2004031417A - Water-proof method for power-circuit unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-proof method for power-circuit wherein the effective water proof of the power-circuit unit is made possible by a simple method, and further, the request of the miniaturization of a power module can be satisfied while maintaining the performance of the power-circuit unit. <P>SOLUTION: The water-proof method for power-circuit unit includes a case manufacturing process for manufacturing a case which has a superimposing surface 3a to be superimposed on a circuit installing surface 2a of a heat dissipating member 2 and has a formed surrounding groove 34 capable of surrounding a power-circuit portion 1, a bonding-agent filling process for filling a bonding agent 4a into the formed surrounding groove 34, and a seal forming process for so superimposing on the superimposing surface 3a filled with the bonding agent 4a the circuit installing surface 2a of the heat dissipating member 2 as to form a sealing member 4 for sealing the clearance between the case 3 and the heat dissipating member 2 by the bonding agent 4a. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for waterproofing a power circuit portion including a bus bar and a semiconductor element and disposed on a heat radiating member via an insulating layer, for example, a power circuit for performing power distribution from a common vehicle power supply to a plurality of electronic units. Related to the waterproofing method of the part
[0002]
[Prior art and its problems]
Conventionally, as a means for distributing power from a common on-board power supply to each electronic unit, a power circuit unit is configured by laminating a plurality of bus bar boards, and an electric connection box in which a fuse and a relay switch are incorporated is known. Have been.
[0003]
In such an electric connection box, the power circuit portion is housed in a case formed of a lower case and an upper case, and the lower case and the upper case are fitted in a watertight manner from the viewpoint of preventing a short circuit or the like, so that the inside of the case is formed. Generally, waterproofing is provided.
[0004]
By the way, in recent years, a power module in which a semiconductor switching element such as an FET is interposed between an input terminal and an output terminal in place of the relay has been developed in order to realize miniaturization of the electric junction box and high-speed switching control. From the viewpoint of cooling the heat generated from the semiconductor element, there has been proposed a power module in which a power circuit portion is provided via an insulating layer on a circuit mounting surface of a heat radiating member. (For example, JP-A-11-204700).
[0005]
In such a power module as well, it is necessary to prevent a short circuit or the like as in the above-mentioned conventional electric connection box. Therefore, the waterproofness of the circuit portion is required. There is no disclosure of the method.
[0006]
Here, similarly to the above-mentioned conventional electric connection box, the power module can be housed inside a case composed of a lower case and an upper case, and the power module can be waterproofed by this case. When the entire power module is housed in the case, heat cannot be sufficiently dissipated, and the performance and reliability of the semiconductor element may not be maintained at a high level.
[0007]
Moreover, when the power module is housed in the case, it is against the demand for downsizing the power module.
[0008]
SUMMARY OF THE INVENTION The present invention provides a method for waterproofing a power circuit section that can achieve effective waterproofing with a simple method and that can maintain the performance of the power circuit section while satisfying the demand for downsizing the power module. The purpose is to:
[0009]
[Means for Solving the Problems]
In order to solve the above problems, the present invention is a method for waterproofing a power circuit portion provided on a circuit disposing surface of a heat dissipating member, the method including a superposed surface for overlapping the circuit disposing surface of the heat dissipating member. Then, a case manufacturing step of manufacturing a case in which a surrounding groove capable of surrounding the power circuit unit is formed on the overlapping surface, an adhesive filling step of filling the surrounding groove with an adhesive, and the adhesive is filled. A step of superposing the circuit arrangement surface of the heat dissipating member on the overlapped surface and forming a seal member for sealing between the case and the heat dissipating member with the adhesive.
[0010]
According to this method, since the seal member is formed by the adhesive to seal between the case and the heat radiating member, the gap between the two members is surely closed by the adhesiveness of the adhesive, and the adhesive is formed in this state. By reliably sealing with the sealing member to be used, the power circuit portion can be effectively waterproofed by a simple method. That is, when a method of sandwiching a sealing member made of, for example, silicon rubber or the like instead of an adhesive in sealing the case and the heat radiating member as in the present invention is employed, the overlapped surface of the case may be warped or the like. In some cases, the degree of parallelism between the overlapped surface and the circuit arrangement surface is low, and in this case, there is a local gap between the sealing member and the overlapped surface or the circuit arrangement surface. In the invention, even if the parallelism is low to some extent, this can be absorbed by the adhesive. In addition, since the adhesive is filled in the surrounding groove provided on the overlapped surface of the case, it is possible to reliably seal the two members at a desired position along the surrounding groove. In addition, since the circuit arrangement surface of the heat radiating member is superimposed on the overlapping surface filled with the adhesive in the surrounding groove and assembled to the case, the heat radiating member is not housed in the closed space inside the case, and the heat radiating member Can perform its function to sufficiently dissipate heat, and maintain the performance of the power circuit section at a high level. In addition, since the waterproofing is achieved by effectively utilizing the heat radiating member that emits heat from the power circuit unit, a lower case is not required, and the device can be configured to be more compact than a conventional electrical junction box.
[0011]
In this method, the adhesive preferably contains a thermosetting resin, and the seal forming step preferably includes a step of thermally curing the adhesive. According to this method, since the adhesive contains a thermosetting resin, after being heated and cured to form a seal member, it is necessary to surely waterproof even under a relatively high temperature atmosphere due to heat generated from the power circuit portion. Can be.
[0012]
Further, in the case manufacturing step, the case manufactured in this step is provided with a cylindrical hood projecting to the side opposite to the heat radiating member, and the external connection terminal bent from the power circuit unit is inserted therethrough. A terminal through-hole for projecting into the hood is provided inside the surrounding groove, and after the case manufacturing step, the assembling step, and the seal forming step, a potting agent is inserted into the case, and the potting agent penetrates the terminal. It is preferable to include a potting step of filling the hood until it protrudes from the hole into the hood, and a hood waterproofing step of filling a waterproof resin over a predetermined height in the hood after the potting step.
[0013]
According to this method, since the potting agent is filled in the case, the potting agent can cover the power circuit portion and more reliably radiate heat. In addition, since the potting agent is filled until it protrudes into the hood from the terminal through-hole, the filling of the potting agent can be confirmed, so-called defective products can be easily detected, and the quality can be easily controlled. can do. In addition, since the hood is filled with a waterproofing resin to be waterproofed, it is possible to prevent water from entering the case passing through the through hole for the terminal and to further ensure the waterproofness of the power circuit portion. Can be. In addition, since the potting agent is filled until the potting agent protrudes from the terminal through-hole as described above, the injected waterproofing resin does not flow into the case through the terminal through-hole, and accordingly, a predetermined amount of the waterproofing resin is provided. Allows the waterproof layer to be formed over a predetermined height, and ensures that the terminal through-holes are waterproofed, while easily adjusting the height of the waterproof layer by adjusting the amount of the waterproofing resin used. can do.
[0014]
Further, when the potting step and the hood waterproofing step are performed as described above, in the case manufacturing step, the seal is formed between the surrounding groove and the terminal through-hole on the overlapping surface of the case to be manufactured. It is preferable to provide a relief groove for releasing an excess amount of the adhesive used in the step and preventing the adhesive from entering the terminal through hole.
[0015]
That is, if the adhesive is excessively filled in the surrounding groove, if the protruding adhesive reaches the terminal through-hole, the potting agent from the terminal through-hole is sealed by the sealing member formed of the adhesive. The protrusion may be hindered. Therefore, according to this method, since the surplus adhesive is released to the release groove, the situation in which the sealing member formed of the adhesive closes the terminal through hole is avoided. For this reason, the potting agent can be protruded from the terminal through-hole without hindrance, and a product with poor filling can be detected more reliably, and the terminal through-hole can be more reliably waterproofed.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
A preferred embodiment of a waterproofing method for a power circuit unit according to the present invention will be described with reference to the drawings. Here, a power circuit unit that distributes electric power supplied from a common power supply mounted on a vehicle or the like to a plurality of electric loads is shown, but the use of the power circuit unit according to the present invention is not limited to this. The present invention can be widely applied to a power circuit unit requiring heat radiation and waterproofing.
[0017]
The power circuit unit 1 to be waterproofed by the waterproofing method of the present embodiment is a main part of a power module as shown in FIG. As shown in FIG. 2, the power circuit unit 1 includes a bus bar configuration plate 10 in which a plurality of bus bars 10 a are arranged in a substantially rectangular area in a predetermined pattern, and a bus bar 10 a configuring the bus bar configuration plate 10. And a plurality of FETs 11 which are semiconductor switching elements interposed between the input terminal bus bar 10a and the output terminal bus bar 10a, and the FET 11 adhered to one surface (the upper surface in FIG. 2) of the bus bar constituting plate 10. And a control circuit board 12 having a control circuit for controlling the switching operation of the FET. The FET 11 is electrically connected to both the bus bar component plate 10 and the control circuit board 12. Further, in the power circuit section 1, an external connection terminal 13 is formed in which a predetermined end portion of the bus bar 10a of the bus bar constituting plate 10 is vertically bent and connected to an external terminal. The external connection terminals 13 function as, for example, an input terminal, an output terminal, or a signal input terminal. In the present embodiment, these terminals are arranged in a row at a pair of opposed side edges of the bus bar configuration plate 10. .
[0018]
The specific shape and configuration of the power circuit unit 1 are not particularly limited, and may be appropriately changed depending on the use of the power circuit unit 1 and the like. For example, the shape of the bus bar component plate 10 and the arrangement pattern of the bus bars 10a are changed, the FET 11 is changed to another semiconductor switching element or another semiconductor element other than the switching element, and the control circuit board 12 is Can be changed so as to be arranged above the FET 11.
[0019]
As shown in FIG. 2, the power circuit section 1 is provided on a circuit mounting surface 2 a of the heat radiating member 2 via an insulating layer 20. The heat dissipating member 2 is entirely formed of a material having excellent thermal conductivity such as an aluminum-based metal, has a flat upper surface, and is configured as a circuit mounting surface 2a. A plurality of radiating fins 2b arranged side by side are provided to protrude downward.
[0020]
Further, the heat radiating member 2 is provided with an insulating layer 20 as shown in FIG. 5 in a region corresponding to the power circuit portion 1 in a central portion of the circuit arrangement surface 2a. The insulating layer 20 is thermally connected to the heat radiating member 2, and is formed by applying, for example, an adhesive having a high insulating property (for example, an adhesive made of an epoxy resin, a silicone adhesive, or the like) and drying it. Alternatively, it is formed by sticking an insulating sheet on the circuit arrangement surface 2a.
[0021]
As shown in FIG. 5, a locking groove 22 is formed in the left and right side walls of the heat radiating member 2 to lock a locking claw 32a of a holding portion 32 of the case 3 described later.
[0022]
In order to dispose the power circuit unit 1 on the circuit disposition surface 2a of the heat dissipating member 2 via the insulating layer 20, for example, the power circuit unit 1 is bonded with an adhesive having high thermal conductivity, or is grounded in the bus bar 10a. If the bus bar 10a is to be included, the bus bar 10a is screwed to the heat radiation member 2.
[0023]
1) Case manufacturing process In order to waterproof the power circuit portion 1 disposed on the circuit disposition surface 2a of the heat dissipating member 2, first, the circuit disposition is performed when the power circuit portion 1 is overlaid on the circuit disposition surface 2a of the heat dissipating member 2. A predetermined case 3 that covers the power circuit section 1 on the surface 2a is manufactured.
[0024]
FIG. 3 is a perspective view showing the case 3 in an upside-down state (a state in which the case 3 is opened upward).
[0025]
The case 3 is made of an insulating material, has a box-like shape that is open on one side and covers the power circuit section 1 from the side opposite to the heat dissipating member 2 (the upper side in FIG. 3), as shown in FIGS. In addition, a case main body 30 forming a peripheral side wall and a case canopy 31 for closing an upper end opening (a lower end opening in FIG. 3) of the case main body 30 are provided.
[0026]
As shown in FIGS. 3 to 5, the case main body 30 of the case 3 has a substantially rectangular annular overlapping surface 3a which is superimposed on the circuit disposing surface 2a of the heat radiating member 2. Of the edges, a pair of outer edges corresponding to the external connection terminals 13 of the power circuit section 1 are provided with holding portions 32 that face each other so as to protrude downward. A locking claw 32a that locks into the second locking groove 22 is provided to protrude inward.
[0027]
As shown in FIGS. 3 to 6, the overlapping surface 3a has a plurality of terminal through holes 33 through which the external connection terminals 13 are inserted, and the heat radiation member provided outside the terminal through holes 33. 2 includes a surrounding groove 34 capable of surrounding the power circuit section 1 and a relief groove 35 inside the surrounding groove 34 and outside the terminal through hole 33 to separate them.
[0028]
The terminal through-hole 33 is provided at a position corresponding to the external connection terminal 13 of the power circuit section 1, that is, at a position corresponding to the external connection terminal 13, with a cross-sectional shape corresponding to the cross-sectional shape of the terminal 13. In the present embodiment, the case body 30 is provided at both left and right edges of the case body 30 so as to penetrate the case body 30. Further, the terminal through-hole 33 is formed in a tapered shape so that the opening area decreases from the inside of the case body 30 to the outside, so that the external connection terminal 13 can be easily inserted.
[0029]
The surrounding groove 34 is formed in a rectangular ring shape along the overlapped surface 3a so as to surround the power circuit unit 1 as described above, and its cross-sectional shape is not particularly limited. It is formed in a shape. As described later, the surrounding groove 34 is filled with an adhesive 4a containing a thermosetting resin along the groove 34, and the depth is appropriately set in consideration of the adhesive 4a to be filled. Is done.
[0030]
The relief groove 35 is provided inside the surrounding groove 34 and outside the terminal through-hole 33 as described above, and in the present embodiment, as shown in FIG. (The direction in which the external connection terminals 13 are arranged at the edges). The relief groove 35 may be provided in a meandering shape, a jagged shape, or the like, but is provided linearly in the present embodiment. Further, the cross-sectional shape of the relief groove 35 is not particularly limited, but in the present embodiment, the cross-sectional shape is U-shaped. The escape groove 35 is for letting out the excess of the adhesive 4a filled in the surrounding groove 34. Therefore, the depth of the escape groove 35 is set in consideration of the material of the adhesive 4a, the amount of the adhesive 4a, and the like. Is set to a sufficient degree. In the present embodiment, the relief grooves 35 are provided continuously, but may be provided discontinuously, that is, provided intermittently corresponding to the terminal through-holes 33. The escape groove is set to be longer than the corresponding terminal through-hole 33.
[0031]
On the other hand, on a surface of the case body 30 opposite to the overlapping surface 3a, a hood 36 for forming a connector formed corresponding to each external connection terminal 13 of the power circuit portion 1 is provided. That is, the case main body 30 is provided with a cylindrical hood 36 projecting to the opposite side of the heat radiating member 2 at both left and right edges thereof, and the external connection terminal 13 of the power circuit section 1 is used for the terminal of the case main body 30. The case main body 30 is configured to protrude into the hood 36 from the through hole 33. Each hood 36 and the corresponding external connection terminal 13 constitute an external connector that can be connected to another connector. Therefore, the sectional shape of the hood 36 is appropriately set in consideration of the shape of another connector to be connected. In the present embodiment as well, a plurality of types of hoods 36 having a cross-sectional shape are provided.
[0032]
The case main body 30 is provided with a drain hole 37 having one end opened in each of the hoods 36 and the other end opened on the heat radiation member 2 side of the case main body 30 and outside the surrounding groove 34. The water in the hood 36 is discharged to the heat radiating member 2 side of the case 3. Further, a pair of fin covers 39 is provided on both ends in the longitudinal direction of the case body 30 so as to protrude along the heat radiating fins 2 b of the heat radiating member 2. When the power module of the present embodiment is disposed with the longitudinal direction as the height direction, the lower end side fin cover 39 has a notch 40 for discharging the drainage from the drain hole 37 to the outside. Is provided.
[0033]
The case canopy 31 is formed in a substantially rectangular shape corresponding to the opening of the case body 30, and is provided with a poaclon 38 for adjusting the air pressure inside and outside the case 3. The case canopy 31 can be attached to the case main body 30 by bonding, welding, or the like.
[0034]
2) Adhesive Filling Step The surrounding groove 34 of the case 3 manufactured by the case manufacturing step is filled with the adhesive 4a.
[0035]
Specifically, first, as shown in FIG. 6, the surrounding groove 34 of the case 3 is filled with an adhesive 4a containing a thermosetting resin. The adhesive 4a is preferably a semi-solid material such as a gel containing a thermosetting resin. For example, a silicone-based adhesive 4a is used. The filling of the adhesive 4a is performed by, for example, an automatic injection machine that is automatically controlled. Needless to say, the material of the adhesive 4a is not limited to the above, and any material may be used as long as it has an adhesive property and has a certain shape-retaining property.
[0036]
As described above, since the adhesive 4a is filled in the surrounding groove 34 provided on the overlapped surface 3a of the case 3, it is possible to reliably seal the two members 2 and 3 at a desired location as described later. Further, since the adhesive 4a contains a thermosetting resin, after the adhesive 4a is heated and cured to form the sealing member 4 as described later, the adhesive 4a is heated in a relatively high temperature atmosphere due to heat generated from the power circuit section 1. However, the sealing function can be sufficiently exhibited.
[0037]
3) Seal forming step Then, the heat dissipating member 2 provided with the power circuit section 1 is assembled to the case 3 in which the surrounding groove 34 is filled with the adhesive in the adhesive filling step, and then heated and the case is heated. A seal member 4 is formed between the heat radiation member 3 and the heat radiation member 2 to seal both members 2 and 3.
[0038]
Specifically, first, after the adhesive 4 a is completely filled in the surrounding groove 34 of the case 3 as described above, the circuit arrangement surface 2 a of the heat radiation member 2 is overlapped on the overlapping surface 3 a of the case 3. That is, the heat dissipating member 2 is fitted into the space surrounded by the holding portion 32 of the case 3 and the fin cover 39 from the power circuit portion 1 side, and the overlapping surface 3a and the circuit disposing surface 2a are connected to each other. The overlapping and the locking claws 32 a of the holding portion 32 are locked in the locking grooves 22 of the heat radiation member 2. At this time, if the adhesive 4a is excessively filled, the adhesive 4a compressed by the heat radiating member 2 overflows from the surrounding groove 34 and extends outside or inside the surrounding groove 34 along the overlapping surface 3a. spread. The adhesive 4a spread inside the surrounding wall flows into the escape groove 35 and does not reach the terminal through hole 33. Therefore, even if the seal member 4 is formed by heating, the terminal through hole 33 is formed by the seal member 4. Is not blocked.
[0039]
As described above, the case 3 is overlaid on the circuit arrangement surface 2a of the heat radiating member 2, and the heat radiating member 2 is exposed to the outside without being housed in the closed space inside the case. By exerting its function, heat is sufficiently dissipated, so that the performance of the power circuit section 1 and thus the performance of the power module can be maintained at a high level. Further, since the waterproofing is achieved by effectively using the heat radiating member 2 that emits heat from the power circuit section 1, a lower case is not required, and the device can be configured to be more compact than a conventional electrical junction box.
[0040]
Further, the case 3 is provided with a relief groove 35 between the surrounding groove 34 and the terminal through-hole 33 on the overlapped surface 3a of the case 3 to be manufactured, so that the adhesive 4a is used as described above. The situation where the terminal through-hole 33 is closed is avoided. For this reason, when the adhesive 4a is thermally cured to form the seal member 4 and the potting agent is subsequently injected as scheduled, the potting agent is allowed to protrude from the terminal through-hole 33 without any trouble as described later. Can be.
[0041]
Next, when the assembled case 3 and heat dissipating member 2 are heated, the adhesive 4a containing the thermosetting resin is cured, and the sealing member 4 is formed. That is, the seal member 4 is formed by the adhesive 4a, and the space between the case 3 and the heat radiation member 2 is sealed.
[0042]
The sealing member 4 formed by thermosetting the adhesive 4a has a substantially rectangular annular shape surrounding the power circuit portion 1, and the sealing member 4 is provided between the heat radiating member 2 and the case 3 by the two members 2, 3. It is interposed in a bonded state.
[0043]
As described above, after the case 3 is assembled to the heat radiating member 2 with the adhesive 4a containing a thermosetting resin, the adhesive 4a is thermally cured to form the seal member 4, so that, for example, the warp is generated on the overlapped surface 3a of the case. Therefore, even when the degree of parallelism between the overlapping surface 3a and the circuit arrangement surface 2a is low, the gap between the two members 2 and 3 can be absorbed. That is, since the sealing member 4 is formed by the adhesive 4a to seal between the case 3 and the heat radiating member 2, the gap between the two members 2 and 3 is closed by the adhesiveness of the adhesive 4a, and in this state, the sealing is performed. Therefore, it is possible to achieve effective waterproofing of the power circuit section by a simple method.
[0044]
4) Potting Step Subsequently, the inside of the case 3 is sealed by filling the inside of the case 3 with an appropriate potting agent. The potting agent is filled until the potting agent protrudes from the terminal through hole 33 into the hood 36. In this state, the power circuit unit 1 is sufficiently covered with the potting agent inside the case 3 in a state where the filling is performed until the terminal circuit hole 33 protrudes from the terminal through-hole 33.
[0045]
Since the potting agent is injected into the case 3 as described above, the potting agent covers the power circuit unit 1 to radiate heat more reliably, and when the potting agent having a waterproof property is injected, the potting agent becomes more reliable. Thus, the power circuit section 1 can be waterproofed. Moreover, since the potting agent is filled until the potting agent protrudes from the terminal through-hole 33, the filling of the potting agent can be confirmed. In this protruding state, the power circuit section 1 is covered with the potting agent. Therefore, for example, a so-called defective filling product in which the power circuit section 1 is not covered with the potting agent can be easily detected, and the quality can be easily controlled.
[0046]
5) Hood waterproofing process After the potting process, a waterproof resin is filled over a predetermined height in the lower portion of the hood 36. That is, a waterproof resin is filled into the lower portion of the hood 36 from above the potting agent protruding into the hood 36, and the waterproof resin 5 forms the waterproof layer 5 to seal the terminal through-hole 33. At this time, the external connection terminal 13 projects from the waterproof layer 5 by a predetermined length at the tip end thereof. As the waterproof resin filled in the hood 36, for example, an epoxy resin or the like is used.
[0047]
As described above, the potting agent is filled until it protrudes into the hood 36 from the terminal through-hole 33, and then the hood 36 is filled with a waterproofing resin to be waterproofed. By preventing water from entering the power circuit section 1, the waterproofness of the power circuit section 1 is reliably ensured. Moreover, since the potting agent is filled so as to protrude from the terminal through-hole 33, the waterproof layer 5 can be formed over a predetermined height with a predetermined amount of the waterproofing resin, and the waterproofing process is reliably performed. On the other hand, the height of the waterproof layer 5 can be easily adjusted by adjusting the usage amount of the waterproof resin.
[0048]
Although the waterproofing method for the power circuit unit 1 according to the present embodiment has been described above, the waterproofing method according to the present invention is not limited to the above-described embodiment, and various modifications may be made without departing from the spirit of the present invention. Is possible.
[0049]
For example, in the above embodiment, the seal member is formed by heat-curing the adhesive, but the method of forming the seal member is not limited to this method, and the heat radiating member is attached to the waterproof case and left for a predetermined time. By doing so, the adhesive may be naturally cured to form a seal member.
[0050]
【The invention's effect】
As described above, the present invention provides a case for manufacturing a case having a superposed surface for superimposing on the circuit disposition surface of the heat radiating member and having a surrounding groove formed on the superposed surface so as to surround the power circuit unit. A manufacturing process, an adhesive filling step of filling the surrounding groove with an adhesive, and a circuit disposing surface of the heat dissipating member are superimposed on the overlapping surface filled with the adhesive, and the adhesive and the case and the heat dissipating member are overlapped. And a seal forming step of forming a seal member for sealing the gap between the members, so that the overlapped surface of the case has a warp or the like, the degree of parallelism between the overlapped surface and the circuit arrangement surface is low, and a local Even if there is a gap, the gap between the two members is closed by the adhesiveness of the adhesive, and in this state, the power circuit portion can be effectively waterproofed by sealing with a seal member. Moreover, it is possible to reliably seal between the two members at a desired location along the surrounding groove, and to superimpose the circuit arrangement surface of the heat dissipating member on the overlapping surface filled with the adhesive in the surrounding groove to form a case. Since the heat dissipating member is assembled, the heat dissipating member can perform its function and dissipate heat sufficiently without being stored in the closed space inside the case, and the performance of the power circuit section is maintained at a high level. Can be. In addition, since the waterproofing is achieved by effectively utilizing the heat radiating member that emits heat from the power circuit unit, a lower case is not required, and the device can be configured to be more compact than a conventional electrical junction box.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a power module to which a waterproofing method for a power circuit unit according to an embodiment of the present invention is applied.
FIG. 2 is a perspective view showing a power circuit unit and a heat radiating member in the power module.
FIG. 3 is a perspective view showing a case in the power module.
FIG. 4 is a bottom view showing a case in the power module.
FIG. 5 is a sectional view taken along line VV of FIG. 1;
FIG. 6 is an explanatory view showing a process of attaching a case and a heat radiation member.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 power circuit portion 2 heat radiating member 2 a circuit arrangement surface 3 case 3 a overlapping surface 4 sealing member 5 waterproof layer 13 external connection terminal 33 terminal through hole 34 surrounding groove 35 relief groove 36 hood

Claims (4)

What is claimed is: 1. A method for waterproofing a power circuit portion provided on a circuit disposition surface of a heat dissipating member, comprising a superimposed surface for overlapping the circuit disposition surface of the heat dissipating member. A case manufacturing step of manufacturing a case having a surrounding groove that can be surrounded, an adhesive filling step of filling the surrounding groove with an adhesive, and a circuit disposing surface of the heat dissipating member on the overlapped surface filled with the adhesive And forming a seal member for sealing between the case and the heat radiating member with the adhesive. 2. The waterproofing method for a power circuit section according to claim 1, wherein the adhesive includes a thermosetting resin, and the seal forming step includes a step of thermally curing the adhesive. . 3. The method for waterproofing a power circuit section according to claim 1, wherein in the case manufacturing step, the case manufactured in this step is provided with a cylindrical hood protruding on a side opposite to the heat radiating member. A terminal through-hole for inserting the external connection terminal folded up from the power circuit portion and projecting into the hood is provided inside the surrounding groove,
After the case manufacturing step, the assembling step, and the seal forming step, the potting agent is filled into the case, until the potting agent protrudes from the through hole for the terminal into the hood, and the potting step of filling, and after the potting step, A hood waterproofing step of filling a waterproof resin over a predetermined height in the hood. 4. The method for waterproofing a power circuit section according to claim 3, wherein in the case manufacturing step, the adhesive used in the seal forming step is formed between the surrounding groove and the terminal through-hole on the overlapping surface of the manufactured case. A method for waterproofing a power circuit section, comprising providing a relief groove for preventing excess adhesive from entering the through hole for a terminal by releasing an excess.

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