JP3569451B2 - Electronic equipment with heat dissipation device - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an electronic device including a heat radiating device, and more particularly to an electronic device including a heat radiating device for a heating element housed in a limited space of a metal housing.
[0002]
[Prior art]
In recent years, the amount of heat generated tends to increase due to an increase in the mounting density of electronic components such as semiconductor elements on a printed board provided inside a metal housing, and an efficient cooling structure is required. In response to such a demand, there is a configuration as shown in FIG.
[0003]
FIG. 9 shows that the heat generated from the high heat generating element 17 mounted on the printed board 11 is diffused into the copper foil 13 provided in a layered manner in the printed board, and the copper foil 13 has an insulating property through the back of the printed board. The bag 10 (for example, made of Kapton resin) in which a liquid refrigerant (for example, Fluorinert (trade name, manufactured by 3M)) is sealed, transfers heat to the housing 10. However, the heat transfer by the refrigerant enclosing bag 19 utilizes natural heat radiation, and cannot sufficiently cope with an increase in the amount of heat generated in recent years.
[0004]
Therefore, cooling has been conventionally performed using a cooling fan. FIG. 10 shows a heat dissipation structure using such a conventional cooling fan. The heating element 30 is mounted on one of the substrates 34 provided in parallel, and the heat receiving section 31 is mounted on the upper surface thereof. A fan 40 is attached to the other side of the substrate 34, and air is collided with the heat receiving portion 31 on the discharge side of the fan 40 to cool the substrate. Since the fan mounted on the substrate 34 directly cools the heat generating element 30 to which the heat receiving unit 31 arranged opposite thereto is mounted, the thickness cannot be reduced. Further, such a cooling fan 40 has a problem that the mounting height of the fan device is increased due to a structure using an axial fan and requiring a casing 41 as a venturi mechanism.
[0005]
11 and 12 show another example of a heat dissipation structure using a conventional cooling fan. FIG. 11 is a perspective view illustrating a conventional heat sink with a fan. A cooling fan (not shown) is attached to the center of such a heat sink with a fan. Air is introduced into the upper side of the intermediate plate and exits through the holes drilled in the plate on the opposite side of the plate and through the heat sink.
[0006]
FIG. 12 shows a structure in which such a heat sink with a fan 33 is mounted on a substrate 34 inside the housing to cool the heating element 30 on the substrate 34. A top view is shown in the upper part of FIG. 12, and a front view is shown in the lower part in a sectional view. The heat generated by the heat generating element 30 is transferred to a heat receiving portion 31 mounted on the upper portion thereof, and from there to a heat radiating portion of a heat sink 33 with a fan connected thereto through a heat pipe 32, and is cooled. Is done. With such a configuration, an excellent cooling effect can be improved, but since the heat sink with fan 33 is mounted on the substrate 34, there is a problem that the mounting height is increased. Particularly, in a portable device such as a notebook personal computer, a sufficient space for mounting the conventional heat sink with fan 33 cannot be secured.
[0007]
For this reason, a heat radiating structure as shown in FIG. 13 is conventionally used in a notebook personal computer or the like. The heating element 30 attached to the back surface of the substrate 34 is in contact with a protrusion 37 provided on the housing 10 via a heat conductive sheet 36. Such a heat radiating structure also utilizes natural heat radiating, and has a problem that not only the cooling effect is not sufficient, but also that the surface temperature of the housing on the lower surface of the protrusion 37 is locally increased.
[0008]
[Problems to be solved by the invention]
Therefore, the present invention increases the cooling efficiency in a system employing a forced cooling structure using a cooling fan so as to be able to sufficiently cope with a large heating value, and is particularly suitable for small electronic devices. Another object of the present invention is to save space, facilitate assembly, and reduce costs.
[0009]
[Means for Solving the Problems]
An electronic apparatus including the heat radiating device of the present invention includes a metal housing 10, a substrate 34 on which a heating element 30 mounted inside the housing 10 is mounted on a front surface or a back surface, and a heat radiating device for the heating element 30. And The board 34 is attached to one wall surface of the housing 10 in parallel with the wall surface. The fan 26 of the heat radiator is mounted on the board 34, on the opposite side of the wall surface, or on the wall surface. The heat radiating portion 27 is provided between the substrate 34 and the wall surface, and is formed integrally with the wall surface. The heat transfer section thermally connects the heat radiating section 27 and the heat receiving section 31 attached to the heating element 30. The air introduced by the fan 26 from the housing intake port 23 is cooled through the hole formed in the substrate 34 to the heat radiating portion 27 on the opposite side of the substrate 34, and is discharged from the housing exhaust port 24. As described above, according to the present invention, the housing 10 is made of metal, and its heat conductivity is arranged so as to be effectively used as the heat radiating portion 27 of the heat radiating device. By using the substrate 34 for mounting the heating element 30 and fixing without using an intermediate plate, space can be saved and cooling efficiency can be increased.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a front view and a top view illustrating an example of an electronic apparatus including a heat dissipation device to which the present invention is applied. In the figure, 10 is a housing, and 34 is a substrate. As shown, the substrate 34 is mounted parallel to and against one wall surface of the housing. (Note that the illustrated devices are not necessarily used in the horizontally illustrated arrangement, but in the following description, this wall surface may be referred to as a bottom surface for convenience.) The fan 26 faces the bottom surface. On the opposite side to the above, it is mounted on the substrate 34. In addition, the elements for controlling the fan 26, except for the Hall element, can be installed on the substrate 34, whereby the thickness of the fan substrate portion is reduced and the mounting height is reduced.
[0011]
The duct 25 introduces cooling air from the intake port 23 above the substrate 34 and guides the air to the fan unit. The fan 26 guides the introduced air to the opposite side through a hole formed in the substrate 34, cools it through the heat radiating portion 27 provided therein, and then out of the housing 10 through the exhaust port 24. Release. As shown in the figure, the positions of the intake port 23 and the exhaust port 24 are arranged so as to avoid the intake from the same side surface of the housing 10 and to take the air from the plane perpendicular to the exhaust surface so that the exhaust does not wrap around. .
[0012]
A heat pipe 32 that is connected to a heating element, which will be described in detail later, is connected to the heat radiating unit 27. The heat pipe 32 can be provided on the side surface of the heat radiating portion 27. However, if the heat pipe 32 is provided on the upper surface thereof, the mounting work becomes easy. Further, the heat pipe 32 can be provided on the upper surface of the heat radiating section 27 and can be suppressed by the substrate 34.
[0013]
The housing 10 is made of a metal such as an Mg alloy that is lightweight, has high strength, and has high thermal conductivity. Then, in order to further improve the thermal conductivity, the inner surface of the metal casing 10 can be plated with copper. As a result, the thermal conductivity in the direction perpendicular to the thickness direction of the housing 10 can be increased, so that the temperature difference on the housing surface is eliminated, the uniformity of the housing surface is promoted, and the cooling is contributed. The area to be used increases. A plurality of fins constituting the heat radiating portion 27 and ribs for mounting a substrate are integrally formed on the housing 10 with a mold at the time of manufacturing the housing.
[0014]
FIG. 3 is a top view of the heat dissipating portion 27 shown in FIG. FIG. 4 shows another example of such a fin shape. The three views of FIG. 4 each show a top view on the top and a front view on the bottom. As shown, the fin shape can be square pin fin, round pin fin, or plate fin. The fins of the heat dissipating portion 27 smoothly flow in and out of the air flow from the fan 26 to effectively cool the heat conducted from the high heat generating element to the heat pipe 32, and to reduce the conducted heat to the metal casing. A plurality are provided at appropriate positions so as to be diffused into the body. In this way, some of the fins of the heat radiating portion 27 function as a venturi mechanism 29 for the purpose of separating the exhaust of the fan from the intake and directing the exhaust in one direction. Further, the ground layer 12 inside the substrate 34 can be used to diffuse the heat conducted to the heat radiating portion 27.
[0015]
FIG. 2 shows details of the portion A shown in FIG. The substrate 34 is entirely made of an insulating resin, but has a ground layer 12 made of copper foil or the like having good thermal and electrical conductivity inside. The conducted heat is transmitted to the ground layer 12, and then from the ground layer 12 via the screws 14 and the like, and further conducted to the fins (or the ribs for mounting the substrate 34) constituting the heat radiating portion 27 fastened by the screws 14. Is transmitted to the housing 10 which is integrally formed. Further, the thermal conduction between the fins of the ground layer 12 and the heat radiating portion 27 is further improved by a thermal bonding that covers the inner peripheral surface of the screw mounting hole formed in the substrate 34 with the copper plating layer 20, that is, a thermal via. Can be.
[0016]
5 to 8 are diagrams illustrating heat transfer from the heating element 30 to the heat radiating section 27. FIG. 5 shows an example in which the heat generating element 30 on the back side of the substrate and the heat radiating section 27 are connected by a heat pipe. The illustrated heating element 30 is an electronic element that generates heat so as to require cooling, and is mounted on a substrate 34 on which the fan 26 is mounted, on the opposite side to the fan 26. A heat receiving section 31 is attached to the heating element 30, and the heat receiving section 31 and the heat radiating section 27 are thermally conductively connected by a heat pipe 32. The airflow introduced above the substrate 34 by the fan 26 is guided to the opposite side of the substrate 34 through a hole formed in the substrate 34, and after cooling the radiator 27 composed of a plurality of fins as described above. Is released to the outside of the housing 10.
[0017]
FIG. 6 is a diagram illustrating an example in which a heat transfer unit from the heating element 30 to the heat radiating unit is configured by a contact unit and a bottom wall integrated with the housing. The heating element 30 is similarly attached to the back side of the substrate 34, and the heating element 30 is in contact with a contact portion 37 protruding from the housing 10 via a heat conductive sheet. In addition, although the temperature locally rises on the back surface of the contact portion 37, the contact prevention portion 38 having the back surface of the housing 10 with unevenness is provided to reduce the contact area with the operator, thereby reducing the operation. Can reduce the body's perceived temperature. The heat generated from the heating element 30 is transferred to the bottom of the housing via the heat conductive sheet and the contact portion 37, and the bottom of the housing constitutes a heat transfer section. Further, since the portion on the bottom surface side of the housing opposing the fan constitutes a heat radiating portion, the airflow introduced by the fan 26 cools the bottom surface side of the housing constituting the heat radiating portion, and then the heating element 30 and After the contact part 37 is directly cooled, it is discharged from the exhaust port 24 to the outside of the housing. The air flow path from the fan 26 to the exhaust port 24 is constituted by the substrate 34, the housing 10, and the duct 20.
[0018]
FIG. 7 illustrates a configuration similar to that of FIG. 6, but includes a plurality of fins 39 in the air flow path. By providing the fins 39 integrally formed with the housing 10, the heat radiation area can be increased and the flow of wind can be made smooth.
[0019]
FIG. 8 shows an example in which heat is transferred from the heating element 30 on the upper side of the substrate to the heat radiating section 27 on the lower side of the substrate using the carbon graphite 40. In the illustrated example, the heat generating element 30 is mounted on the substrate 34 on the upper side similarly to the fan 26. Since the heat radiating portion 27 is provided on the lower side of the substrate 34 opposite to the side on which the fan 26 is mounted, the carbon graphite 40 extends from the upper heating element 30 of the substrate 34 to the lower heat radiating portion 27. Thermally coupled. Although carbon graphite is inferior in heat transfer compared to heat pipes, it is thin enough to allow it to pass through even small gaps. It has the advantage of absorbing manufacturing and assembly tolerances of parts. By using such carbon graphite, the heat is conducted from the heating element 30 to the back surface through the gap on the side surface of the substrate, and is sandwiched between the heat radiating portion 27 and the substrate 34 and tightened with screws. Since carbon graphite is conductive, it must be sandwiched with an insulating resin except for a contact portion when used.
[0020]
FIG. 14 is a diagram exemplifying attachment of the fan 26 to the board 34. As shown, the bearing house 42 and the fan board 43 of the fan 26 are attached to the rib 41. Then, the rib 41 is fixed to the side of the substrate 34 opposite to the bottom surface of the housing 10, and the main part of the fan 26 is attached so as to project from the hole formed in the substrate 34 to the bottom surface of the housing. Can be This allows the fan 26 to be mounted with a minimum height above the board.
[0021]
FIG. 15 is a diagram showing another example of attachment of the fan 26 to the board 34. In the figure, the bearing house 42 and the fan board 43 of the fan 26 are attached to the bottom side of the housing 10. This allows the fan 26 to be mounted without requiring any ribs for mounting and hardly protruding from the holes provided in the substrate 34, and the air flow is generated from the upper side of the substrate 34 corresponding to the fan 26. The hole can be satisfactorily guided to a heat radiating portion (not shown) through the hole.
[0022]
【The invention's effect】
The present invention effectively utilizes the thermal conductivity of a metal housing as a heat radiating portion of a heat radiating device, and further mounts a fan on an electronic element without using an intermediate plate as conventionally required. By using a circuit board for fixing or using holes made in the board as air passages, it is possible to attach to recent electronic devices that are thin and have limited mounting space. In addition to this, there is an effect that not only the mounting height can be sufficiently reduced, but also forced air cooling that can cope with a large amount of heat generation is enabled.
[0023]
In addition, the intermediate plate becomes unnecessary in this way, and furthermore, by integrating the heat radiating portion and the housing, the number of molds is reduced from two to one, so that the cost can be reduced.
[0024]
Further, by integrating the heat radiating portion and the housing, the contact thermal resistance between the heat radiating portion and the housing is reduced, and the heat radiating efficiency is increased.
[Brief description of the drawings]
1A and 1B are a front view and a top view illustrating an example of an electronic apparatus including a heat radiating device to which the present invention is applied.
FIG. 2 is a diagram showing details of a portion A shown in FIG. 1;
FIG. 3 is a top view illustrating the fin shape of the heat radiating unit shown in FIG. 1 with other components omitted for clarity;
FIG. 4 is a view showing another example of the fin shape of the heat radiation unit.
FIG. 5 shows an example in which a heat pipe is connected from a heat generating element on the back side of the substrate to a heat radiation portion on the back side of the substrate.
FIG. 6 shows an example in which a heat transfer section from a heating element to a heat radiating section is constituted by a contact section and a bottom wall integrated with a housing.
FIG. 7 is a diagram illustrating a configuration similar to that of FIG. 6, but including a plurality of fins in an air flow path.
FIG. 8 shows an example in which heat is transferred from a heating element on the upper side of the substrate to a heat radiation portion on the lower side of the substrate using carbon graphite.
FIG. 9 is a diagram showing a cooling configuration of an electronic device using a conventional refrigerant enclosing bag.
FIG. 10 shows a heat dissipation structure using a conventional cooling fan.
FIG. 11 is a perspective view illustrating a conventional heat sink with a fan.
FIG. 12 shows another example of a heat dissipation structure using a conventional cooling fan.
FIG. 13 is a diagram illustrating a heat dissipation structure used in a conventional notebook personal computer or the like.
FIG. 14 is a diagram exemplifying attachment of a fan to a board;
FIG. 15 is a view showing another example of attachment of the fan to the board.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Case 12 Ground layer 14 Screw 20 Copper plating layer 23 Intake port 24 Exhaust port 25 Duct 26 Fan 27 Heat radiating part 29 Venturi mechanism 30 Heating element 31 Heat receiving part 32 Heat pipe 33 Heat sink with fan 34 Substrate 36 Thermal conductive sheet 37 Projection 38 Contact prevention part 39 Fin 40 Carbon graphite 41 Rib 42 Bearing house 43 Fan substrate part

Claims (8)

In a metal housing, a substrate having an electronic element mounted inside the housing and requiring cooling, mounted on a front surface or a back surface, and an electronic device including a heat dissipation device for the electronic element,
The substrate is mounted parallel to and against one wall surface of the housing;
The heat dissipation device, on a substrate parallel to the wall surface, a fan mounted on the side opposite to the wall surface, and a heat radiation unit provided between the substrate and the wall surface, and integrally formed with the wall surface, A heat transfer portion that thermally conductively couples the heat radiating portion and a heat receiving portion attached to the electronic element,
The air introduced by the fan from the housing intake port cools the radiator on the opposite side of the substrate through a hole formed in the substrate, and is discharged from the housing exhaust port.
An electronic device comprising a heat dissipation device. In a metal housing, a substrate having an electronic element mounted inside the housing and requiring cooling, mounted on a front surface or a back surface, and an electronic device including a heat dissipation device for the electronic element,
The substrate is mounted parallel to and against one wall surface of the housing;
The heat radiator includes a fan mounted on the wall, a heat radiator provided between the substrate and the wall, and formed integrally with the wall, and a heat receiver mounted on the heat radiator and the electronic element. And a heat transfer unit that thermally conductively couples
Air introduced by the fan from the housing intake port, cools the radiator through a hole formed in the substrate corresponding to the fan, and discharges the air from the housing exhaust port.
An electronic device comprising a heat dissipation device. An electronic device comprising the heat radiating device according to claim 1, wherein the heat radiating unit includes a plurality of fins formed integrally with a housing. 4. An electronic apparatus comprising the heat radiating device according to claim 1, wherein the heat transfer unit is formed of a heat pipe or carbon graphite. 5. The heat radiating portion is a housing portion opposed to the fan, and the heat transfer portion is interposed between the contact portion and the electronic element formed by projecting integrally with the housing. An electronic device comprising the heat radiating device according to claim 1, comprising a heat conductive sheet. An electronic apparatus comprising the heat radiating device according to claim 5, wherein a contact preventing portion having an uneven surface is formed on a rear surface side of the housing provided with the contact portion. The substrate is provided with a ground layer having high heat conductivity inside in a layered manner, and the substrate is attached to the fins of the heat radiating portion or the ribs for attaching the substrate by using screws, so that the ground layer and the fins or ribs are heated. The heat radiation according to any one of claims 1 to 6, wherein the thermal bonding is improved by covering the inner peripheral surface of the hole of the screw mounting substrate with a copper foil in addition to the thermal bonding. Electronic equipment equipped with a device. 8. An electronic apparatus comprising the heat radiating device according to claim 1, wherein heat conduction is improved by plating the inner surface of the housing with copper.

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