JP6866648B2 - Electronic device housing - Google Patents

Description

The present invention relates to a housing of an electronic device, and more particularly to a waterproof structure of a housing of an electronic device installed outdoors.

In electronic devices exposed to outdoor rainwater, a sealed housing is generally adopted for the purpose of waterproofing the electronic circuits.

For example, Patent Document 1 describes a structure in which the heat radiating fins are sealed with a sealing plastic by an insert molding method and integrally molded with the housing so that a part of the heat radiating fins is exposed from a part of the housing. Has been done.

Japanese Unexamined Patent Publication No. 9-18176

In the housing of the conventional electronic device described in Patent Document 1, as shown in FIG. 9, a circuit board on which an electronic component as a heating element is mounted is connected to a heat radiation fin made of an aluminum alloy via a heat radiation sheet. A hole is made in the housing so that a part of the heat radiating fin is exposed, and the housing structure is integrated with a sealing plastic. In this case, when the heat radiating fin is made of a metal having high thermal conductivity, there is a problem that stress is generated due to the difference in the characteristics of the plastic and the metal and peeling due to an external force occurs in an outdoor installation environment. As a result, a gap may be generated around the heat radiation fins, so that sufficient airtightness cannot be ensured due to inundation of water, and the case is not suitable as a housing for electronic devices to be installed outdoors.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a housing of an electronic device capable of improving waterproofness while maintaining heat dissipation performance.

The housing of the electronic device of the present invention is a housing of an electronic device that houses a substrate assembly including a substrate that carries an electronic circuit, and joins a resin wall portion that surrounds the substrate assembly and an opening of the wall portion. It has a resin heat-dissipating portion integrally molded on the surface, and the joint surface between the wall portion and the heat-dissipating portion is a convex portion extending in a direction perpendicular to the thickness direction of the heat-dissipating portion and the convex portion. It is characterized by including a recess that fits into the.

According to the housing of the electronic device of the present invention, the heat of the electronic circuit can be efficiently transferred from the heat radiating portion to the outside of the housing by the joint surface of the convex portion and the concave portion between the wall portion and the heat radiating portion. Moreover, the airtightness is improved, heat dissipation performance and waterproof performance can be achieved at the same time, and by partially forming the heat dissipation portion of the high heat conductive resin, it is possible to realize a housing having high heat dissipation at low cost.

In the housing of the electronic device of the present invention, the joint surface can be configured to include a plurality of surfaces that intersect the surface of the wall portion at a predetermined angle other than 90 degrees, thereby increasing the strength of the housing. It can be improved and stress distribution can be promoted.

In the housing of the electronic device of the present invention, the outer shell of the heat radiating portion can be configured to have a circular shape, whereby peeling of the wall portion and the heat radiating portion due to aging can be suppressed.

In the housing of the electronic device of the present invention, the concave portion can be configured to be provided with a bite portion toward the convex portion, thereby improving the adhesion of the joint surface and the wall portion due to aging. The peeling of the heat radiating portion can be further suppressed.

In the housing of the electronic device of the present invention, the heat radiating portion can be configured to have higher thermal conductivity than the resin of the wall portion, whereby the heat radiating performance can be improved.

In the housing of the electronic device of the present invention, the heat radiating portion can be configured to have a plurality of heat radiating protrusions protruding into the external space of the housing, whereby the heat radiating performance can be further improved.

In the housing of the electronic device of the present invention, the heat radiating portion and the wall portion can be configured to be molded in two colors, whereby the ease of assembling the housing can be improved.

It is a perspective view seen from the lid body side which shows the appearance of the housing body of the electronic device which is Example 1 by this invention. FIG. 5 is a schematic cross-sectional view showing a housing of an electronic device in line xx of FIG. FIG. 2 is a schematic cross-sectional view of an enlarged portion in which the joint surface portion Jp of the housing body of the housing of the electronic device and the heat radiating portion in FIG. 2 is enlarged. It is a schematic cross-sectional view of an enlarged part which enlarged the joint surface part of the housing body of the housing body of the electronic device of a comparative example, and a heat dissipation part. FIG. 2 is a schematic cross-sectional view of an enlarged portion in which the joint surface portion Jp of the housing body of the housing of the electronic device and the heat radiating portion in FIG. 2 is enlarged. FIG. 2 is a schematic cross-sectional view of an enlarged portion in which the joint surface portion Jp of the housing body of the housing of the electronic device and the heat radiating portion in FIG. 2 is enlarged. It is schematic cross-sectional view of the mold explaining the manufacturing process of the housing of the electronic device which is Example 1 by this invention. It is schematic cross-sectional view of the mold explaining the manufacturing process of the housing of the electronic device which is Example 1 by this invention. It is schematic cross-sectional view explaining the assembly process of the housing of the electronic device which is Example 1 by this invention. It is schematic cross-sectional view explaining the assembly process of the housing of the electronic device which is Example 1 by this invention. It is the schematic sectional drawing of the housing of the electronic device which is Example 2 by this invention. FIG. 5 is a schematic cross-sectional view of an enlarged portion of an enlarged joint surface portion between a housing body and a heat radiating portion of a housing of an electronic device according to a third embodiment of the present invention. It is schematic cross-sectional view which shows the housing of the conventional electronic device.

Hereinafter, the housing of the electronic device for outdoor installation according to the embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the following examples. In the examples, components having substantially the same function and configuration are designated by the same reference numerals, so that duplicate description will be omitted.

FIG. 1 is a perspective view showing the appearance of the housing 10 of the electronic device according to the first embodiment as viewed from the lid body side. FIG. 2 is a schematic cross-sectional view showing a housing 10 of an electronic device in line xx of FIG.

As shown in FIGS. 1 and 2, the resin housing 10 of the electronic device of the embodiment has a substantially rectangular parallelepiped shape. The housing 10 is composed of a pair of tubular box-shaped housing bodies 11 and a lid 12, and are fitted to each other at their respective openings. The housing body 11 has a flange 11F that projects outward from the side wall of the open end surface. The lid 12 projects outward from the side wall of the open end surface and has flanges 12F on each other. By fitting the flanges 11F and the flange side surfaces of the lid 12 of the housing body 11 and the lid 12, a sealed storage space for accommodating electronic components or devices inside the housing body 11 and the lid 12. SP is defined.

As shown in FIG. 2, the housing body 11 and the lid 12 are fastened with screws Sc or the like (FIG. 1) in a state where the packing 24 is sandwiched between the facing surfaces of the flanges 12F and 11F and fitted. Stick to each other. By removing the lid 12 from the housing 10, the inside of the housing can be accessed.

The housing body 11 has a heat radiating portion 14 made of a heat conductive resin integrated with an opening of a wall portion at the bottom thereof. The heat radiating portion 14 includes a heat radiating main body 14A fitted in the opening of the wall portion at the bottom and a heat radiating protruding portion 14P (a plurality of fins protruding in parallel at a predetermined pitch) exposed to the outside from the heat radiating main body. The heat radiating portion 14 is integrally molded from a heat conductive resin having a higher heat conductivity than the resin of the housing body 11.

A substrate (board assembly) of an electronic circuit 18 on which an electronic component 17 as a heating element is mounted is fixed to a heat radiating main body 14A (inside the housing main body 11) via a heat conductive sheet 16 directly stretched. .. The heat conductive sheet 16 is made of a metal such as copper or aluminum or ceramics. In this way, the heating element (electronic component 17) is thermally connected to the heat radiating portion 14 by the heat conductive sheet.

As shown in FIGS. 1 and 2, the outer shell of the joint surface J of the heat radiating portion 14 that is joined to the housing body 11 has a circular shape. FIG. 3 is a schematic cross-sectional view of an enlarged portion of the joint surface portion Jp (broken line circle) of the housing body of the housing of the electronic device and the heat radiating portion in FIG. As shown in FIG. 3, for example, the joint surface J of the heat radiating body 14A of the heat radiating portion 14 includes a joint surface JA tapered to the inside of the housing and a joint surface JB substantially parallel to the surface of the plate-shaped heat radiating portion. It is composed of a joint surface JC having a reverse taper shape inside the housing, which is opposite to the joint surface JA in an angular direction. That is, the joint surface J is formed so as to include a convex portion P extending in a direction perpendicular to the thickness direction of the heat radiating portion 14 and a concave portion R fitted to the convex portion. Further, the concave portion R is provided with a biting portion R1 toward the convex portion P.

When the housing 10 including the electronic device of this embodiment is installed in the field, the temperature of the entire housing changes depending on the heat of the heating element of the electronic component and the ambient air temperature. In such a situation, since the housing body 11 and the heat radiating portion 14 made of different materials have different linear expansion coefficients, stress is generated on the joint surface J between the housing body 11 and the heat radiating portion 14 as shown in FIG. To do.

Since the joint surface J of the heat radiation main body 14A has a composite shape of the joint surfaces JA, JB, and JC, the area of the joint surface J is dramatically larger than the joint area of the conventional structure (for example, the whole is shown). Refer to the joint surface JD (joint surface without recesses and protrusions) shown in the enlarged schematic cross-sectional view (FIG. 4) of the joint surface portion between the housing body and the heat radiation portion of the housing body of the electronic device of the comparative example. Please give me). Therefore, the stress (FIG. 3) of the heat radiating portion 14 generated by the temperature change is dispersed on the wide joint surface. Further, since the heat radiating portion 14 is formed in a circular shape (FIG. 1), stress concentration does not occur on the joint surface J. The heat radiating portion 14 may have an elliptical shape or a polygonal shape in addition to the circular shape, and various shapes may be adopted depending on the molding die.

Further, as shown in FIGS. 5 and 6, when an external force is applied to the heat radiating portion 14, the joint surface JA and the joint surface JC are tapered in opposite directions, so that the external force is applied to the joint surfaces JA and JC. It is distributed as a force along each surface and a force perpendicular to the surface. That is, as shown in FIG. 5, when an external force is applied to the heat radiating portion 14 from the inside to the outside, the external force is dispersed into a force along the surface of the reversely tapered joint surface JC and a force perpendicular to the surface. Further, as shown in FIG. 6, when an external force is applied to the heat radiating portion 14 from the outside to the inside, the external force is dispersed into a force along the surface of the tapered joint surface JA and a force perpendicular to the surface. In particular, the external force is dispersed by the bite portion R1 provided in the recess of the joint surface JA.

The manufacturing process of the housing of the electronic device of the Example will be described with reference to FIGS. 7 to 10. In the manufacturing process, the housing body 11 integrated with the heat radiating portion 14 is formed by two-color molding, and the housing of the electronic device is manufactured through the component arranging step and the sealing step.

As shown in FIG. 7, in the first molding step of two-color molding, the mold D1 for the heat radiating portion is molded on the base mold BD to form a heat radiating portion cavity in the internal space thereof, and the heat radiating portion cavity is formed therein. A predetermined resin material for the heat radiating part is injected, and the heat radiating part 14 is molded in one color. Only the mold D1 is removed from the mold BD to expose the heat radiating portion 14 of the molded product on the base mold BD to remove burrs and the like. Since the heat-dissipating portion mold D1 is a pair of molds that are movable in the extending direction of the plurality of parallel fins of the heat-dissipating protruding portion 14P, the mold D1 is a molded product when the mold D1 is opened in the horizontal direction. The convex portion P of the heat radiating portion 14 of the above is not damaged.

Examples of the resin material for the heat radiating part include high heat conductive PC (polycarbonate), high heat conductive PBT (polybutylene terephthalate), high heat conductive PPS (polyphenylene sulfide), high heat conductive PA (polyamide) and the like. The high thermal conductivity resin material of the resin material for the heat radiating part is basically a mixture of an existing resin material with a filler, carbon, etc. in order to improve the thermal conductivity.

Next, as shown in FIG. 8, in the second molding step of the two-color molding, the mold D2 for the housing is molded on the heat radiating portion 14 on the base mold BD, and the mold for the housing is molded. In a state where only the heat radiating main body 14A of the heat radiating portion 14 is arranged in the internal space of the mold D2, a predetermined housing resin is injected into the internal space to mold the housing main body 11 in two colors. By the two-color molding, the heat radiating body 14A of the heat radiating portion 14 is integrated with the housing body 11, and the heat radiating body 14A is fitted and joined to the housing body 11. Next, the molded product of the housing body 11 integrated with the heat radiating portion 14 is taken out from the base mold BD and the mold D2, and burrs and the like are removed.

Examples of the resin material for the housing include ABS (acrylic nitrile butadiene styrene), PC (polycarbonate), ASA (acrylate styrene acrylic nitrile), AES (acrylonitrile ethylene-propylene-diene styrene), ABS-PC and the like.

Next, as shown in FIG. 9, in the component arranging step, the heat conductive sheet 16 is directly stretched on the heat radiating portion 14 (the flat bottom portion of the heat radiating body 14A). After that, the substrate assembly of the electronic circuit 18 on which the electronic component 17 as a heating element is mounted is fixed with a constant load by screws or the like (not shown).

Next, as shown in FIG. 10, in the sealing step, the flange 12F of the lid 12 is aligned with the flange 11F of the housing body 11 via the packing 24, and the side surfaces of the flanges are fitted to each other, and screws and the like are used. Fix with a constant load (not shown). As a result, the housing 10 of the sealed electronic device accommodating the electronic component 17 shown in FIG. 2 is completed. A connection hole (not shown) for passing an external power supply cable, an input / output cable, etc. for operating the housed electronic circuit is provided in a part of the side wall of the housing body 11 except for the heat radiation portion 14. It is provided.

As described above, by molding the housing body 11 and the heat radiating portion 14 in two colors, the adhesion between the heat radiating portion 14 and the housing body 11 is improved. Further, since the contact thermal resistance of the joint surface (boundary surface) between the housing body 11 and the heat radiating portion 14 becomes small, heat is efficiently transferred from the heating element to the heat radiating portion 14, and the heat radiating protruding portion 14P of the heat radiating portion 14 becomes the atmosphere. By being exposed to the heat, the heat is radiated directly to the atmosphere without going through the housing body 11.

As described above, according to the present embodiment, the heat radiating portion 14 and the housing body 11 are molded in two colors inside the housing to ensure the airtightness in the heat radiating structure of the resin housing and to dissipate heat. Can be expected to improve.

Further, in addition to the effect of improving heat dissipation, according to this embodiment, the heat dissipation unit 14 and the housing body 11 are integrated, and the sealing plastic covering the electronic components is not required, so that the assembly man-hours are reduced. Furthermore, since the sealing plastic is not required, the board assembly can be replaced even if the board assembly of the electronic circuit 18 fails.

Further, in the conventional structure, when a substrate on which an electronic component that generates heat is mounted is housed, the heat conductivity is small and the heat dissipation is low with a general housing resin material. Therefore, in order to improve the heat dissipation, the entire housing is required. It was necessary to increase the size or to use a resin having high thermal conductivity as the resin material for the entire housing. Therefore, when the housing is enlarged, the size of the device is increased and the weight is also increased, so that the installation conditions are deteriorated. Further, when a high thermal conductive resin is used for the entire housing, there is a problem that the manufacturing cost is higher than that of using a general resin. However, according to this embodiment, since the high thermal conductive resin can be partially used in the required portion, the effect of reducing the manufacturing cost can be obtained.

In the first embodiment described above, the heat radiating portion 14 is provided on the housing body 11 side, but the heat radiating portion 14 can also be provided on a side surface other than the bottom portion of the housing body or on the lid side. For example, as shown in FIG. 11, in the second embodiment, the heat radiating portion 14 is also molded in two colors on the lid 12 side, and the electronic component 17 is brought into contact with the heat conductive sheet 16 or the like to further dissipate heat. Can be improved.

In the third embodiment, as shown in FIG. 12, the joint surface J of the heat radiating body 14A of the heat radiating portion 14 does not have a joint surface substantially parallel to the surface of the heat radiating portion, and has a tapered joint surface JA inside the housing. The housing 10 includes an electronic device having the same configuration as that of the first embodiment, except that the joint surface JA is formed of a joint surface JC having a reverse taper shape inside the housing in a direction different from that of the joint surface JA. That is, the joint surface J of the heat radiating body 14A of the heat radiating portion 14 in the third embodiment includes a convex portion P extending in a direction perpendicular to the thickness direction of the radiating portion 14 and a concave portion R fitted to the convex portion. Further, the concave portion R is provided with two biting portions R1 toward the convex portion P. According to this, since the convex portion P is sandwiched between the two biting portions R1, the strength of the housing body 11 can be expected to be improved.

10 ... Housing 11 ... Housing body 12 ... Lid body 11F, 12F ... Flange 14 ... Heat dissipation part 14A ... Heat dissipation body 16 ... Heat conduction sheet 17 ... Electronic component 18 ... Electronic circuit 24 ... Packing JA, JB, JC ... Joint surface R1 ... Biting part Sc ... Screw SP ... Storage space

Claims (6)

A housing for electronic devices that houses a board assembly that includes a board that carries electronic circuits.
A resin wall surrounding the substrate assembly and
It has a resin heat-dissipating portion integrally molded on the joint surface of the opening of the wall portion.
The junction surface between the heat radiating portion and the wall portion, viewed contains a recess to be fitted to the convex portion and the convex portion extending in a direction perpendicular to the thickness direction of the heat radiating portion,
The housing of an electronic device, characterized in that the heat radiating portion has a plurality of heat radiating protrusions protruding into the external space of the housing. The housing of an electronic device according to claim 1, wherein the joint surface includes a plurality of surfaces that intersect the surface of the wall portion at a predetermined angle other than 90 degrees. The housing of an electronic device according to claim 1 or 2, wherein the outer shell of the heat radiating portion has a circular shape. The housing of an electronic device according to any one of claims 1 to 3, wherein the concave portion is provided with a biting portion toward the convex portion. The housing of an electronic device according to any one of claims 1 to 4, wherein the heat radiating portion has higher thermal conductivity than the resin of the wall portion. The housing of an electronic device according to any one of claims 1 to 5, wherein the heat radiating portion and the wall portion are molded in two colors.

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