JP2001085878A - Electronic equipment unit - Google Patents

Abstract

(57) [Summary] To provide an electronic device unit having good heat radiation efficiency. A substrate (6) on which electronic components are mounted, a shield plate (7) surrounding the substrate (6) and shielding an external electromagnetic field, and a substrate (6)
The electronic device unit 1 includes a resin case 3 for accommodating the shield plate 7 and mounting portions 3g, 3m, and 3n provided on the bottom 3c of the resin case 3 and mounting the resin case 3 on the rails 20. The heat radiation metal plate 8 is attached only to the lower surface 3e of the resin case bottom 3c, and the shield plate 7 is in contact with the inner surface 3d of the resin case bottom 3c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electronic equipment unit having good heat radiation efficiency.

[0002]

2. Description of the Related Art On a production line or an inspection line of a factory, a multiple sensor 100 is installed as shown in FIG. 9, and the multiple sensor 100 uses a large number of electronic equipment units 101 as detectors. ing. The electronic device unit 101 includes, for example, an optical fiber 102 and an amplifier unit 103 that performs signal processing by photoelectrically converting a signal from the optical fiber 102. Amplifier section 103
Is a substrate 10 on which electronic components are mounted as shown in FIG.
4 and a shield plate 105 for shielding the substrate 104 from an external electromagnetic field are housed in a resin case 106. The base end of the optical fiber 102 is inserted and fixed at a front wall 106 a of a case 106. The electronic device unit 101 is mounted on a DIN rail (hereinafter simply referred to as “rail”) 107 by a mounting portion (not shown) provided on the bottom of the resin case 106.

[0003] A metal plate 108 for heat radiation is attached to the resin case 106 in order to improve the heat radiation with the miniaturization and thinning of the amplifier unit 103 and the added value of the arithmetic unit. As shown in FIG. 10, the heat-dissipating metal plate 108 has a substantially U-shape in end view, and has side plates 108b, 108b contacting the outer surfaces of both side walls 106b, 106b along the substrate 104 in the case 106, and a bottom 106c. And the bottom plate 108c that contacts the rail 107 are integrally formed.

As shown by arrows in FIG. 10, heat generated from electronic components mounted on the substrate 104 is transmitted to the shield plate 1.
05 → Both side walls 106b of case 106 → Both side plates 108b of metal plate 108 for heat radiation → Bottom plate 108c → Rail 1
The heat is transmitted to the atmosphere from the rail 107 through the path 07. An example of an electronic device unit including such a heat-dissipating metal plate is disclosed in Japanese Patent Application Laid-Open No. 9-162574.

[0005]

However, in the multiple sensor of the above-mentioned construction, since a large number of electronic equipment units 101 are closely arranged, the side wall 106b of the case 106 and the side plate 10 of the metal plate 108 for heat radiation.
8b is adjacent to the side wall 106b of the other electronic device unit 101 and the side plate portion 108b of the metal plate 108 for heat radiation, and there is no escape route for heat. Therefore, the temperature of the side wall 106b of the case 106 is always high, and the temperature difference between the side wall 106b and the shield plate 105 is small. As described above, heat is hardly conducted even when contact is made at a place where the temperature difference between the two is small, so that the temperature of the shield plate 105 and the temperature of the electronic component are reduced until a certain temperature difference occurs between the side wall 106b and the shield plate 105. Will rise. That is, there is a problem that heat radiation efficiency is not good.

[0006] The present invention has been made in view of the above points, and has as its object to provide an electronic device unit having good heat radiation efficiency.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a board on which electronic components are mounted, a shield plate surrounding the board and shielding an external electromagnetic field,
An electronic device unit including a resin case for housing the substrate and the shield plate, and a mounting portion provided on a bottom of the resin case and mounting the resin case on a rail, wherein the resin case is The heat radiation metal plate is attached only to the bottom lower surface, and the shield plate is in contact with the bottom inner surface of the resin case.

[0008] The heat generated from the electronic components is conducted to the entire shield plate surrounding the substrate. On the other hand, the lower surface of the case bottom and the metal plate for heat dissipation are directly thermally connected to the rail, and the rail is always in contact with the atmosphere (in a state of heat dissipation). For this reason, the temperature of the inner surface of the case bottom is always low, and the temperature difference with the shield plate here is large. As described above, heat is easily conducted because the two are in contact at a large temperature difference. Since the shield plate has a very good thermal conductivity, when heat is dissipated in the portion in contact with the inner surface of the bottom portion, the heat of the other portion immediately moves to the portion in contact with the inner surface of the bottom portion. . Thereby, the heat radiation efficiency of the electronic device unit is improved.

According to a second aspect of the present invention, the lower part of the shield plate is adhered to the inner surface of the bottom of the resin case by an adhesion means. Because the lower part of the shield plate is in close contact with the inner surface of the bottom of the case, the shield plate and the inner surface of the bottom are thermally connected well, and the heat transfer from the lower part of the shield plate to the bottom of the case is good, and the heat dissipation efficiency is improved. Is further improved.

According to a third aspect of the present invention, a heat conductive elastic member is provided on a bottom of the resin case, and the lower surface of the heat conductive elastic member forms at least a part of a lower surface of the bottom. It is characterized in that it is in close contact with the shield plate inside the resin case and is in close contact with the metal plate for heat radiation outside. The case with poor heat transfer does not exist in the heat transfer path between the shield plate and the metal plate for heat dissipation, and the heat conductive elastic member is in close contact with the metal plate for heat dissipation, so that the heat dissipation efficiency is improved. Is further improved.

According to a fourth aspect of the present invention, at least one longitudinal end of the heat-dissipating metal plate is pressed against the rail by its spring property. At least one end of the heat-dissipating metal plate is elastically pressed against the rail and is thermally connected well. Therefore, the heat generated from the electronic components inside the case and transmitted from the shield plate to the bottom of the case,
The heat is satisfactorily conducted from the heat-dissipating metal plate to the rails and dissipated.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) As shown in FIGS. 1 and 2, an electronic device unit 1 includes, for example, an optical fiber (not shown) and an amplifier unit 2 which performs signal processing by photoelectrically converting a signal from the optical fiber. A light-emitting element 4, a light-receiving element 5, and a substrate 6 on which electronic components constituting the amplifier are mounted in a thin resin case (hereinafter simply referred to as a "case") 3 that is flat on the left and right. A shield plate 7 that surrounds substantially the entire substrate 6 and blocks an external electromagnetic field is housed. The light emitting element 4 and the light receiving element 5 are optically connected to an end face of the optical fiber mounted on the front wall 3 a of the case 3.

The bottom 3c of the case 3 is provided with a concave portion 3g as a mounting portion for mounting on the rail 20.
The rail portions 20 of the rail 20 are provided on both front and rear sides of the concave portion 3g.
The recesses 3h and 3i slightly recessed are provided opposite to a and 20b. In addition, fixed claws 3j and movable claws 3 as mounting parts for detachably fixing the case 3 to the rail parts 20a and 20b in cooperation with the concave parts 3g on both front and rear sides of the concave parts 3g.
k. A metal plate 8 for heat radiation is mounted in the concave portion 3g of the case 3.

As shown in FIG. 3, the substrate 6 is arranged vertically at the center of the case 3, and its plate surface is fixed along the side walls 3b, 3b in the longitudinal direction. The shield plate 7
As shown in FIGS. 2 and 3, the substrate 6 has a flat cylindrical shape and surrounds the entire substrate 6, and the lower surface 7 a is in contact with the inner surface 3 d of the case bottom 3 c to be thermally connected. As the shield plate 7, for example, a film-like polyimide base having a copper foil adhered on the outside is used. Therefore, the shield plate 7 can be easily curved into the flat cylindrical shape, and has a very good thermal conductivity.

As shown in FIG.
The flat heat-dissipating surface 8a has substantially the same size as the lower surface 3e of the concave portion 3g provided in the case bottom 3c, and small hooks 8b for locking are provided at the front and rear positions on both left and right sides.
It is provided to be bent substantially at right angles to a. Further, the rear portion 8c of the heat radiation surface 8a is bent slightly downward in the shape of a letter. This metal plate 8 for heat radiation
It is formed of a thin metal plate such as copper having good thermal conductivity and elasticity. On the other hand, as shown in FIGS. 1 and 2, the side walls 3b of the case 3 have recesses 3m for accommodating the hooks 8b flush with the hooks 8b at positions corresponding to the hooks 8b of the metal plate 8 for heat dissipation. The engaging claw 3n is formed.

As shown in FIG. 1, the heat dissipating metal plate 8
Is mounted in the recess 3g of the case 3. The heat-dissipating metal plate 8 is taken into the recess 3g from below with the upper portion of each hook 8b slightly widened outward, and
Are housed in the corresponding recesses 3m of both sides 3b of the case 3 and are locked by the locking claws 3n. In this state,
The heat radiating surface 8a contacts the lower surface 3e of the case bottom 3c. As a result, the heat dissipating metal plate 8 becomes
And is thermally connected well.

The electronic device unit 1 in which the metal plate 8 for heat radiation is mounted on the bottom 3c of the case is mounted on the rail 20 via the recess 3g as shown in FIG. Rail 20
Has a substantially concave shape in a side view, and each opening end of the front and rear wall portions is horizontally bent outward to form a flange shape.
a and 20b. Lower surface 3e of case bottom 3c
Are connected to the rails 20a, 2
The fixed claw 3j and the movable claw 3k are placed on the rails 20a and 20b.

On the lower surface 3e of the bottom 3c, the rails 20a,
By providing the recesses 3h and 3i corresponding to 0b, the front and rear ends of the heat radiating surface 8a are slightly pushed up by the rail portions 20a and 20b, and elasticity is provided to press the rail portions 20a and 20b. I do. Further, the heat dissipation surface 8
The rear part 8c of a is slightly bent downward in a U-shape, so that the rear part 8c further comes into pressure contact with the rail part 20b by spring property.
As a result, the front and rear ends of the metal plate 8 for heat radiation closely contact the rail portions 20a and 20b, and are thermally connected well.
Thus, lower surface 3e of case 3 is thermally connected to rail 20 via metal plate 8 for heat radiation.

In the above embodiment, only the rear portion 8c of the heat radiating surface 8a of the heat radiating metal plate 8 is slightly bent in the shape of a letter to provide a spring property, but the concave portion 3h of the case bottom 3c is provided. The front part corresponding to the rail part 20a is also bent slightly downward in the same manner as the rear part 8c to give a spring property, and the rail part 20a
May be brought into pressure contact. When the front part of the heat radiating surface 8a of the heat radiating metal plate 8 is flat as in the embodiment, the concave portion 3h may not be provided on the lower surface 3e of the case bottom 3c. In this case, the front portion of the heat radiation surface 8a is pressed against the rail portion 20a by the lower surface 3e.

As described above, a plurality of electronic equipment units 1 are provided on the rail 20 and the side walls 3b of the adjacent electronic units.
Are abutted and juxtaposed to form a continuous sensor. Each electronic unit 1 is electrically connected to a female connector 9 (FIG. 1) provided on one side wall 3b of the case 3 and a female connector (not shown) provided on the other side wall 3b. Followed.

The operation will be described below. As shown in FIG. 3, heat generated from the electronic components mounted on the substrate 6 is conducted to the entire shield plate 7. Lower surface 7a of shield plate 7
Is in contact with the inner surface 3d of the case bottom 3c by the lower surface of the substrate 6. On the other hand, since the lower surface 3d of the bottom 3c is in contact with the rail 20 via the metal plate 8 for heat dissipation, the temperature of the bottom 3c is substantially close to the temperature of the rail 20. Thus, the lower surface 7a of the shield plate 7 is in contact with the case bottom 3c having a large temperature difference. Therefore, the heat of the shield plate 7 is efficiently transmitted from the lower surface 7a to the case bottom 3c,
Further, the heat is transmitted to the rails 20 through the metal plate 8 for heat dissipation and is radiated.

The shield plate 7 has a very good thermal conductivity because a metal foil such as copper is adhered thereto. When heat is radiated from the case bottom 3c, the heat of the other portions moves to the lower surface 7a immediately. Thus, the heat of the shield plate 7 is radiated from the case bottom 3c to the rail 20 as indicated by the arrow, and the heat conducted to the rail 20 is radiated to the atmosphere. As a result, the heat dissipation efficiency of the electronic device unit 1 becomes very good, and the temperature rise of the electronic components can be suppressed well.

(Embodiment 2) FIGS. 5 and 6 show a second embodiment of the electronic apparatus unit according to the present invention. The same members as those in the first embodiment are denoted by the same reference numerals, and description thereof will be omitted. As shown in FIGS. 5 and 6, the lower surface 7a of the shield plate 7 is adhered to the inner surface 3d of the case bottom 3c by an adhesion means, for example, an adhesive 11 made of a silicone resin member having good thermal conductivity. Thereby, the lower surface 7a of the shield plate 7
However, the area in contact with the inner surface 3d of the case bottom 3c becomes large microscopically even if it is the same as that of the first embodiment macroscopically. As a result, the shield plate 7 is attached to the case bottom 3c.
The heat radiating area increases, and accordingly, the heat radiating effect increases. Thereby, it goes without saying that the same effect as in the first embodiment is obtained, and the transmission efficiency can be further improved.

It is preferable that the adhesive has good heat conductivity, but the adhesive is filled in a minute gap between the inner surface 3d of the case bottom 3d and the lower surface 7a of the shield plate 7.
It goes without saying that the effect is not always required even if the material does not have good thermal conductivity. (Embodiment 3) FIG. 7 shows a third embodiment of the electronic apparatus unit according to the present invention. In the third embodiment, a heat conductive elastic member is used as means for bringing the shield plate 7 into close contact with the inner surface 3d of the case bottom 3c in the second embodiment. In FIG. 7, the thermally conductive elastic member 12 is, for example,
A rubber sheet formed by mixing a silicon-based rubber member with a powder material having excellent thermal conductivity (hereinafter referred to as “rubber sheet 12”)
), The bottom surface 3d has substantially the same size as the inner surface 3d, the lower surface is in contact with the inner surface 3d, and the lower surface 7a of the shield plate 7 is in close contact with the upper surface. The rubber sheet 12 is elastically deformed, fills a minute gap between the rubber sheet 12 and the lower surface 7a of the shield plate 7, and satisfactorily adheres to the lower surface 7a. As a result, the area where the lower surface 7a of the shield plate 7 contacts the inner surface 3d of the case bottom 3c increases microscopically even if it is macroscopically the same as in the first embodiment. Thereby, it goes without saying that the same effect as in the first embodiment is obtained, and the transmission efficiency can be further improved.

(Embodiment 4) FIG. 8 shows a fourth embodiment of the electronic equipment unit according to the present invention. As shown in FIG. 8, the heat conductive elastic member 13 is formed by, for example, mixing a silicon-based rubber member having heat conductivity with a powder material having excellent heat conductivity and molding the mixture (hereinafter referred to as “mold”). Heat transfer element 1
3 "). The heat transfer body 13 has an upper portion 13a having substantially the same size as the inner surface 3d of the case bottom portion 3c, a lower portion 13b being slightly smaller than the upper portion 13a, and having a thickness equal to the plate thickness of the case bottom portion 3c. It has a substantially inverted convex shape, and a concave portion 13c having a substantially arc shape in an end view is provided on the upper surface over substantially the entire length along the longitudinal direction.

On the other hand, a hole 3s into which the lower portion 13b of the heat transfer body 13 is fitted is provided in the case bottom 3c. The heat transfer body 13 is housed in the case 3, and a lower portion 13 b thereof is fitted into the hole 3 s of the case bottom 3 c, and a lower surface 13 d is flush with a lower surface 3 e of the case bottom 3 c, and Closely adhered. That is, the lower portion 13b of the heat transfer body 13 forms substantially the entire case bottom 3c, and the lower surface 13d of the heat transfer body 13 is in direct contact with the metal plate 8 for heat radiation over the entire surface. Then, the lower surface 7a of the shield plate 7 is fitted and closely fitted to the recess 13c.

The resin case 3 is not interposed in the heat transfer path between the shield plate 7 and the heat-dissipating metal plate 8, and the heat transfer member 13 having elasticity directly adheres to the heat-dissipating metal plate 8. By increasing the microscopic contact area at that portion, the heat radiation effect is enhanced. Since the material of the resin case must be selected with priority given to strength and ease of molding, a material having poor heat transfer properties may be used. Even in such a case, the heat dissipation effect is enhanced by not interposing a resin case having poor heat transferability in the heat transfer path between the shield plate 7 and the metal plate 8 for heat dissipation.

Further, since the resin case 3 is not interposed in the heat transfer path between the shield plate 7 and the heat-dissipating metal plate 8, even if a material having poor heat transfer properties is used as the material of the resin case 3, it is high. There is no change in the heat dissipation effect. Therefore, for example, it is possible to select a material such as ABS resin by giving priority to strength, moldability, cost and the like regardless of heat transferability. That is, the range of choice of materials for the resin case is expanded.

In the above embodiment, the heat transfer member 13
The entire lower surface 13d of the heat transfer member 13 constitutes the entire lower surface of the case bottom portion 3c.
A part of the lower surface 13d, for example, the lower surface central portion corresponding to the concave portion 13c on the upper surface may constitute a part of the lower surface of the case bottom 3c. However, it is preferable that the entire lower surface 13d of the heat transfer body 13 constitute the entire lower surface of the case bottom 3c as in the embodiment, since the heat radiation efficiency can be greatly improved.

As described above, the present invention provides an electronic device unit having excellent heat radiation efficiency. In addition, when electronic device units are connected in series as described below, the present invention is much more remarkable than the prior art. It also has a unique merit of reducing the thickness. As in the prior art shown in FIG. 10, when the heat-dissipating metal plate has a substantially U-shape in end view and is in contact with both side walls of the case, even if the plate thickness of the heat-dissipating metal plate is set to 0.2 mm, the processing error may occur. And the thickness of each electronic device unit increases by about 0.8 mm because the electronic device unit is present on both sides of the case. Therefore, when a continuous-type photoelectric sensor that enables up to 16 electronic device units each having a width of 9 mm can be provided, a difference of about 0.8 × 16 = 12.8 mm occurs as a whole. Although it depends on the processing accuracy of the metal plate for heat radiation, even an underestimate would protrude by about one electronic device unit, and when installed in a place where there is not enough space, it cannot be ignored.

On the other hand, in the present invention, the case bottom 3
The heat radiating surface 8a of the metal plate 8 for heat radiating only on the lower surface 3e of c.
Makes it possible to reduce the thickness of the electronic device unit. Note that the hook 8b in the present embodiment is used.
Is housed in the recess 3m whose area is much smaller than the side wall 3b of the case 3 and the thickness of the side wall 3b is reduced by the plate thickness of the hook 8b. Not applicable and not against thinning.

Even in the case where the side plate of the metal plate for heat radiation is present, the electronic device unit can be made thinner if it is accommodated in a recess whose side wall thickness is reduced by the thickness of the side plate. . However, if the area of the concave portion having a small thickness on the side wall is large, the strength of the case against twisting, twisting and the like is significantly reduced, which is practically difficult. on the other hand,
In the embodiment of the present invention, the hook 8b is very small as described above, and accordingly, the area of the recess 3m is also very small, so that the strength of the case is not reduced.

[0033]

As described above, in the first aspect of the present invention, since the shield plate is in contact with the inner surface of the bottom of the case having a large temperature difference, the heat of the shield plate is efficiently radiated, and the heat radiation efficiency of the electronic device unit is reduced. improves. At the same time, the thickness of the electronic device unit can be reduced.

According to the second aspect of the present invention, since the minute gap between the shield plate and the inner surface of the bottom of the case is filled by the close contact means, the heat transfer efficiency is further improved as compared with the first aspect of the present invention. According to the third aspect of the present invention, the case with poor heat transfer does not exist in the heat transfer path between the shield plate and the heat radiating metal plate, and the heat conductive elastic member is in close contact with the heat radiating metal plate. By doing so, heat is radiated even better than in the first and second aspects of the invention. Also, no matter what material is used as the material of the resin case, there is no change in the high heat radiation effect, and the range of choice of the material of the resin case is widened.

According to the fourth aspect of the present invention, at least one end of the heat-dissipating metal plate is elastically pressed against the rail and is thermally connected well, thereby further improving the heat-dissipating effect. Also, rattling is prevented when the electronic device unit is mounted on the rail.

[Brief description of the drawings]

FIG. 1 is a side view showing a first embodiment of an electronic device unit according to the present invention.

FIG. 2 is a partially cutaway view showing a state where the electronic device unit shown in FIG. 1 is mounted on a rail.

3 is a cross-sectional view of the electronic device unit shown in FIG. 2, taken along the line III-III.

FIG. 4 is a perspective view of the metal plate for heat radiation shown in FIG. 1;

FIG. 5 is a partially cutaway side view showing a second embodiment of the electronic device unit according to the present invention.

6 is a cross-sectional view of the electronic device unit shown in FIG. 5, taken along the line VI-VI.

FIG. 7 is a sectional view showing a third embodiment of the electronic device unit according to the present invention.

FIG. 8 is a sectional view showing a fourth embodiment of the electronic device unit according to the present invention.

FIG. 9 is a perspective view showing a state in which a plurality of conventional electronic device units are mounted on a rail.

10 is a cross-sectional view of the electronic device unit shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electronic equipment unit 2 Amplifier part 3 Resin case 6 Substrate 7 Shield plate 8 Heat dissipation metal plate 11 Adhesive (adhesion means) 12 Rubber sheet (thermally conductive elastic member) 13 Heat transfer body (thermally conductive elastic member)

Claims (4)

[Claims] 1. A board on which electronic components are mounted; a shield plate surrounding the board to shield an external electromagnetic field; a resin case for housing the board and the shield plate; and a bottom of the resin case. An electronic device unit provided with a mounting portion for mounting the resin case on a rail, wherein a heat-dissipating metal plate is mounted only on a bottom lower surface of the resin case, and the shield plate is formed of the resin case. An electronic device unit, which is in contact with the bottom inner surface. 2. The electronic device unit according to claim 1, wherein a lower portion of the shield plate is adhered to an inner surface of a bottom portion of the resin case by an adhesion unit. 3. A heat conductive elastic member is provided on a bottom of the resin case, and a lower surface of the heat conductive elastic member forms at least a part of a lower surface of the bottom portion. The electronic device unit according to claim 1, wherein the electronic device unit is in close contact with the shield plate inside the case, and is in close contact with the metal plate for heat radiation outside. 4. The electronic device unit according to claim 1, wherein at least one longitudinal end of the heat-dissipating metal plate is pressed against a rail due to its spring property.