JP2583773B2 - Unit heat dissipation structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] A heat radiation structure of a unit in which heat generated from components mounted on a circuit board is transferred to a unit housing by heat conduction and radiated from the housing, is mounted on the unit. The circuit board is designed to transfer the heat generated by the electronic components mounted on the circuit board to the unit housing and efficiently radiate the heat. The circuit board has upper and lower edges exposed on at least one surface of the metal core (72). The circuit board (7) with a metal core to which the resin board (71) is attached as described above. The concave guide (8) of the unit housing (20) is made of metal and has a hole (81) on at least one side. A two-way curving shape is formed, which straddles the hole in the guide direction in the guide, and is curved toward the concave inner side so as to be a convex portion having a low mountain shape at normal temperature and a convex portion having a high mountain shape at a predetermined temperature or higher. Shape memory alloy The pressing piece (9) is formed so as to be deformable, and the upper and lower exposed metal core portions of the circuit board (7) containing the metal core lightly contact the convex portion of the pressing piece in the unit housing (9). After being inserted into the guide (8) of (20), when the pressing piece (9) reaches a predetermined temperature due to the heat generated on the circuit board with the metal core due to the operation state of the unit, the convex piece of the pressing piece becomes higher. The portion is configured to press the exposed surface of the metal core.

[Industrial applications]

The present invention relates to a heat dissipation structure of a unit that transfers heat generated from components mounted on a circuit board to a unit housing by heat conduction and radiates heat from the housing.

In electronic and communication devices, generally, a large number of circuit boards on which a large number of electronic components are mounted are mounted vertically in a unit housing, and the heat generated from the mounted electronic components is directly conducted to the air to radiate heat. ing. In recent years, the miniaturization of the above devices,
Due to the demand for weight reduction, the electronic components mounted on the circuit board are highly integrated and high-density mounting, which increases the amount of generated heat. It has become difficult to maintain a predetermined temperature rise for operation.

[Conventional technology]

FIG. 4 (a) is a front view of the conventional heat dissipation structure,
(B) is shown in the unit front view. FIG. 4 (a) shows a unit 2 in which a large number of circuit boards 3 on which a large number of electronic components 4 are mounted are mounted along a concave guide 5 provided in the unit housing 20 so as to face each other. As shown in ()), the device 1 is configured by being mounted in a stacking manner in a plurality of stages.

With the operation of the device 1, the heat generated from the electronic components 4 mounted on the circuit board 3 is transmitted to nearby air, which increases the temperature of the air. Through a ventilation hole (not shown) formed in the ceiling plate and the bottom plate of the housing 20, heat is radiated to the outside of the device from below by a chimney effect as indicated by arrows.

According to such a configuration, since the upper unit 2 is cooled by the ascending air of the lower unit 2, the upper unit 2 receives an airflow at a higher temperature than the outside air from the lower unit 2, and furthermore, This tendency is increased in the upper unit 2. Therefore, as shown in FIG.
The heat shield unit 6 is interposed at appropriate intervals with respect to the unit 2. The heat shielding unit 6 is provided with an inclined heat shielding plate 61.
It is provided with. According to this example, the outside air introduced from the right side of the apparatus 1 in the drawing enters the inside from the bottom plate surface of the unit 2 along the inclined upper surface of the heat shield plate 61, and the air heated by the unit 2 is removed from the upper heat shield unit. 6 is discharged to the left outside of the device 1 along the inclined lower surface of the heat shield plate 61. Such a configuration is configured between each unit stage.

[Problems to be solved by the invention]

According to the above-mentioned conventional heat dissipation structure, heat dissipation is limited because the heat dissipation cooling by direct conduction from the electronic components to the air depends on the ventilation flow rate of the air, and particularly large-scale integrated circuits (LSIs) having a large heat dissipation. Since it is necessary to mount a heat dissipation fin for LSI, it is necessary to increase the space between the circuit boards, and the number of circuit boards mounted is reduced. In addition, it is necessary to increase the cooling area by increasing the height of the power transformer, etc., as heat-generating components, which impedes the flow of air and also limits the number of circuit boards mounted in the unit. was there.

[Means for solving the problem]

According to the present invention, the above problems are caused by the metal unit housing (20).
In the heat dissipation structure of the unit in which the circuit board is inserted and mounted in a plurality of concave guides attached to the bottom plate and the ceiling plate so as to face each other in the direction of the facing surface from the opening surface, the circuit board has a metal core (72). A circuit board (7) with a metal core to which a resin substrate (71) is attached so that the upper and lower side edges thereof are exposed on at least one surface of the unit housing (20). A hole (81) is provided on at least one side surface, and the hole extends in the guide direction in the guide, and is formed on the concave inner side so as to have a low mountain-shaped convex portion at normal temperature and a high mountain-shaped convex portion at a predetermined temperature or more. A pressing piece (9) made of a two-way shape memory alloy curved and deformed in a chevron shape is attached so as to be deformable, and the upper and lower exposed metal core portions of the metal cored circuit board (7) are chevron shapes of the pressing piece. The convex part of After being inserted into the guide (8) of the unit housing (20) in a state in which the pressing piece (9) reaches a predetermined temperature due to the heat generated on the circuit board containing the metal core due to the operation state of the unit. The heat dissipation structure of the unit is characterized in that the raised chevron of the pressing piece presses the exposed surface of the metal core.

[Action]

According to the present invention, a hole is provided in the side surface of the concave metal guide attached to the bottom plate and the ceiling plate of the unit housing so as to face each other, and the shape memory alloy is bidirectional in the guide direction across the hole. Further, the pressing plate is curved and deformed so that the pressing plate has a low mountain-shaped convex portion at normal temperature and a high mountain-shaped convex portion at a predetermined temperature or more in the guide inner direction.

Therefore, the pressing plate in the guide is fixed at one end to the side surface of the guide and free at the other end so that such deformation is possible.

On the other hand, the circuit board is a circuit board with a metal core including a metal core and a resin substrate mounted on one surface thereof. The metal core is exposed at upper and lower edges of the metal core. Inserted into body guide.

When the circuit board with the metal core is housed in the unit housing at normal temperature, the convex portion of the pressing plate in the guide is low, so that the exposed metal core portion is formed in the mountain of the pressing plate in the guide. It is easily inserted with light contact.

Further, even if the width of the guide is narrow and the exposed metal core hits the angled portion of the pressing plate, the hole can serve as a relief for the angled portion of the pressing plate, so that the insertion is also easy in this case.

When the unit is activated, the electronic components arranged on the circuit board with the metal core generate heat, and the heat is transferred from the metal core to the pressing plate through the lightly contacting chevron. .

Also, the heat generated by the metal core of the adjacent circuit board with metal core,
The temperature is transmitted to the pressing plate attached thereto through the guide hole, and the temperature of the air around the circuit board also increases, so that the temperature of the pressing plate increases.

As a result, when the pressing plate reaches a predetermined temperature, the convex portion of the pressing plate is deformed and becomes high, and from the state where it has been lightly contacted with the low convex portion of the pressing plate until now, the pressing plate passes through the high convex and the metal core portion. Press strongly.

As a result, the heat generated by the circuit board containing the metal core is transmitted to the guide via the metal core portion and the pressing plate, further transmitted to the housing, and radiated through the wide housing surface.

Further, the temperature of the air around the circuit board containing the metal core also rises and is exhausted to the outside of the device housing the unit.

As a result, the heat generated in the circuit board on which the highly integrated electronic components are mounted at a high density is sufficiently exhausted, and the device can be kept within a predetermined temperature rise.

〔Example〕

Hereinafter, the present invention will be described with reference to FIGS. 1 to 3 according to an embodiment.

1 to 3 show an embodiment of the present invention.
The figure is a perspective view of the unit of the present invention and a circuit board with a metal core,
FIG. 2 is a plan view of the pressing piece, and FIG. 3 is an enlarged perspective view of the guide portion.

In FIG. 1, ventilation holes 12 are formed in a bottom plate 21 and a ceiling plate 22, respectively, of a unit housing 20 formed by bending a metal plate such as an iron plate, and a plurality of pairs of concave guides 8 are provided to face each other. .

A hole 81 is provided in one side surface 82 on the inner side of the guide 8, and a pressing piece 9 curved and formed in a mountain shape so as to straddle this portion is mounted at one end by a mounting bracket 11. As shown in FIG. 2, the pressing piece 9 has a low mountain-shaped convex portion 91 (having a height h) as shown by a solid line at an ambient temperature of about 20 ° C. at room temperature.
When the ambient temperature rises to 35 ° C. or more and becomes a high temperature state, a two-way shape memory alloy is deformed into a high mountain-shaped convex portion 91 ′ (having a height H) as shown by a two-dot chain line. A plate, for example, a titanium-nickel (Ti-Ni) alloy is formed by shape memory so that the shape is changed by the temperature change as described above. That is, it is provided so that the convex portion of the mountain shape becomes higher in the width direction in the guide 8 at a predetermined temperature.

The circuit board is a circuit board 7 having a metal core made of a resin (made of glass fiber and epoxy resin) board 71 and a metal core 72.
The upper and lower side edges 74 of the metal core 72 are exposed, and this portion 74 is a portion to be inserted into the guide 8. Although not shown, a large number of electronic components 4 are mounted and mounted on the circuit board 7 with a metal core, as shown in FIG. 4 (b). Reference numeral 23 in FIG. 1 denotes a back board provided with a printed wiring board for connecting electrical circuits connected to the circuit board 7 with a metal core and a connector, and reference numeral 10 is added to a side surface of the unit housing 20. It is a radiation fin.

With the above configuration, when the unit housing 20 is in a normal temperature state, the pressing piece is in a state of a low mountain-shaped convex portion 91, and this state lightly contacts the side edge 74 of the metal core 72, and Since the insertion of the board into the guide is facilitated, the storage of the metal cored circuit board 7 in the unit housing is simplified.

When the mounting of the circuit board 7 with the metal core is completed and the device is put into an operating state, the circuit board generates heat, and the temperature is transmitted to the pressing piece that is in light contact with the metal core. Further, the heat generated by the adjacent metal cored circuit board is also transmitted to the pressing piece via the hole in which the pressing piece is attached. Furthermore, the temperature of the air in the unit also increases due to the heat generated by the circuit board. When the pressing piece rises to a predetermined temperature, for example, a temperature of 35 ° C. or higher, the pressing piece 9 is in a state of a high mountain-shaped convex portion 91 ′. In this state, the raised chevron-shaped projection 91 'of the pressing piece presses the side edge 74 of the metal core 72, whereby the metal core is pressed and closely contacted with the other side surface 83 of the guide 8. The electronic components 4 are mounted with their package surfaces in contact with the surface of the substrate 7, and heat is transferred to the metal core 72. Further, the heat transmitted through the lead terminals of the electronic component 4 is transmitted to the wiring terminals on the board surface and is transmitted to the metal core 72 from now on.

Therefore, heat is transferred from the surface of the side edge 74 to the guide 8 by pressing,
The heat is also radiated from the surface of the unit housing 20 and the heat radiation fin 10, and the inside is maintained at a predetermined temperature state. Of course, heat is directly transmitted to the air also from the surface of the electronic component 4, and the heat is exhausted through the ventilation holes 12 by natural ventilation.

The heat dissipating fin 10 can be connected to a heat pipe as a heat transfer block, and can transfer heat to a large heat pipe provided at the upper part of the apparatus to dissipate heat.

In the above embodiment, the pressing piece 9 is made of a Ti-Ni alloy. However, the pressing piece 9 is not limited to this, and may be another shape memory alloy exhibiting two directions, such as a copper-zinc (Cu-Zn) alloy or other alloys. Is also good. The pressing piece 9 is attached to one side surface of the guide 8, but it is also possible to attach it to both sides and sandwich and press the side edge 74 of the metal core. Although only one pressing piece 9 is shown, a plurality of holes may be formed in the guide, and each pressing piece may be provided along the guide.

ADVANTAGE OF THE INVENTION According to this invention, it is possible to make a heat-generating component, such as a power transformer, thin and to closely mount it on a circuit board containing a metal core. To remove the circuit board with metal core from the unit,
The unit can be easily taken out by bringing the unit into a normal temperature state or cooling the pressing piece with a cooling agent or the like to lower the temperature.

〔The invention's effect〕

As is clear from the above description, according to the present invention, it is easy to insert and remove the circuit board with a metal core, and when the apparatus is operating, the metal core of the circuit board with a metal core is pressed by the pressing piece and thermally connected. Therefore, the heat radiation drop is improved, which is extremely effective for improving the reliability of the device.

[Brief description of the drawings]

1 to 3 are diagrams for explaining an embodiment of the present invention.
FIG. 1 is a perspective view of the unit of the present invention and a circuit board with a metal core, FIG. 2 is a plan view of a pressing piece, FIG. 3 is an enlarged perspective view of a guide portion, and FIGS. 4 (a) is a front view of a device that dissipates heat by natural ventilation, FIG. 4 (b) is a front view of a unit of FIG. 4 (a), and FIG. 5 is a view of a device using a heat shielding unit. FIG. In the figure, 1 is a device, 2 is a unit, 3 is a circuit board,
4 is an electronic component, 5 and 8 are guides, 6 is a heat shielding unit, 7
Is a circuit board with a metal core, 9 is a pressing piece, 10 is a radiation fin,
11 is a mounting bracket, 12 is a vent, 20 is a unit case, 21
Is a bottom plate, 22 is a ceiling plate, 23 is a backboard, 61 is a heat shield plate, 71 is a resin substrate, 72 is a metal core, 74 is a side edge, 81 is a hole, 8
2,83 indicates a side surface, and 91,91 'indicates a mountain-shaped convex portion.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mitsuaki Suzuki 1015 Uedanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (72) Inventor Katsuki Matsunaga 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Fujitsu Limited ( 56) References Japanese Utility Model Showa 53-43461 (JP, U) Japanese Utility Model Showa 62-73595 (JP, U) Japanese Utility Model Showa 62-26093 (JP, U)

Claims (1)

(57) [Claims] 1. A unit in which a circuit board is inserted and mounted in a plurality of concave guides mounted on a bottom plate and a ceiling plate of a metal unit housing (20) so as to face each other in a direction of an opposing surface from an opening surface. In the heat radiation structure, the circuit board is configured as a metal core-containing circuit board (7) to which a resin substrate (71) is attached so that upper and lower edges of at least one surface of the metal core (72) are exposed. The concave guide (8) of the body (20) is made of metal,
A hole (81) is provided on at least one side surface, and straddles the hole in the guide direction in the guide, and is convex toward the concave inside so as to be a convex portion having a low mountain shape at normal temperature and a convex portion having a high mountain shape at a predetermined temperature or more. A pressing piece (9) made of a two-way shape memory alloy curved and deformed is attached so as to be deformable, and the upper and lower exposed metal core portions of the metal cored circuit board (7) are angled convex portions of the pressing piece. After being inserted into the guide (8) of the unit housing (20) in a state of lightly touching the part, the pressing piece (9) is heated to a predetermined temperature by heat generated on the circuit board containing the metal core due to the operation state of the unit. The heat radiating structure of the unit, wherein when it reaches, the raised convex portion of the pressing piece presses the exposed surface of the metal core.