JP2002111262A - Electronic component heat sink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the number of components and the assembling man-hour from increasing by omitting the conventional insulation sheet for insulating terminals of electronic components from a radiation plate. SOLUTION: An insulation plate 34d between terminals 20b and trenches 31a of a radiation plate 31 is formed integrally with a support member 34. This suppresses the number of components and the assembling man-hour from increasing, compared with means for pasting the conventional insulation plate 40 to the radiation plate 31 as a means for reducing the width of the trenches 31a for preventing the electric discharge between the terminal 20b and the radiation plate 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic component cooling device for cooling a heat-generating electronic component such as a power transistor.

[0002]

2. Description of the Related Art FIG. 4 shows an example of the above-described cooling device. The corrugated fins 32 to be blown to the corrugated fins 32 and the fan 33 for blowing the corrugated fins 32 are supported by a resin support member 34 attached to the printed circuit board 10.

In recent years, as the mounting density of the electronic components 20 has increased, the terminals 20 b of the electronic components 20 arranged at the positions indicated by the two-dot chain lines in FIG. It has to be arranged at a position facing the. Therefore, since the distance between the terminal 20b and the heat radiation plate 31 is reduced, when the current flowing through the terminal 20b is a high voltage (for example, 600 to 700 V), the terminal 20b
Is discharged to the heat radiation plate 31 from the terminal 20.
It has become necessary to insulate between b and the heat radiation plate 31.

On the other hand, the inventor of the present invention has proposed FIG.
As shown in FIG.
A study was made to form a groove 31a in a portion facing b and increase the distance between the terminal 20b and the heat dissipation plate 31.

However, the width L1 of the groove 31a (FIG. 4)
(See (c)) to increase the insulation,
On the contrary, the portion of the ultrasonic bonding surface of the heat radiation plate 31 corresponding to the groove 31a (the portion indicated by the symbol P in FIG. 4A) is such that the ultrasonic vibration energy is applied to the heat radiation plate 31 during ultrasonic bonding. Heat dissipation plate 3
The portion P corresponding to the first groove 31a and the corrugated fin 32
It has been found that there is a risk of poor bonding with the metal. Further, if the width L1 of the groove 31a is increased, the heat conductivity of the heat dissipation plate 31 from the electronic component 20 side to the opposite side to the groove 31a is reduced with respect to the groove 31a, and the cooling capacity of the cooling device is reduced. It is possible to do it.

The inventor of the present invention has proposed that the insulating sheet 40 made of an insulating material shown by the hatched portion in FIG.
Is attached to a portion of the lower surface facing the terminal 20b to reduce the width L1 of the groove 31a. In addition, a gap CL is provided between the insulating sheet 40 and the electronic component 20.
(See FIG. 4 (a).) Since it is difficult to securely attach the terminal 20b to the terminal 20b and the heat radiating plate 31, it is difficult to eliminate the groove 31a and to use only the insulating sheet 40 to insulate the terminal 20b from the heat radiation plate 31. Have difficulty.

[0007]

However, in the above cooling device, since the insulating sheet 40 is attached to the heat radiating plate 31, the insulating sheet 40, which is a single component, causes an increase in the number of components, and the attaching operation is difficult. This has led to an increase in the number of assembly steps.

SUMMARY OF THE INVENTION In view of the above, the present invention eliminates the conventional insulating sheet and insulates between the terminals of the electronic component and the heat radiation plate to suppress an increase in the number of components and an increase in the number of assembly steps. With the goal.

[0009]

In order to achieve the above object, according to the first aspect of the present invention, the electronic component (20) is joined to the surface of the electronic component (20) opposite to the substrate (10) to form the electronic component (2).
A radiation plate (31) for dissipating heat from the substrate (10) and a support member (34) mounted on the substrate (10) to support the radiation plate (31).
The terminal (20b) of the electronic component (20) and the heat radiation plate (3
(1) An insulating plate (34d) made of an insulating material disposed therebetween is integrally formed.

Thus, the insulating plate (34d) disposed between the terminal (20b) and the heat radiating plate (31).
Is integrally formed with the support member (34), so that the conventional insulating sheet can be eliminated, and an increase in the number of parts and an increase in the number of assembling steps can be suppressed.

According to the second aspect of the present invention, the electronic component (20) is bonded to the surface of the electronic component (20) opposite to the substrate (10) and faces the terminal (20b) of the electronic component (20). A radiator plate (31) having a radiator plate (31a); a fin (32) joined to a surface of the radiator plate (31) on a side opposite to the electronic component (20) to promote heat radiation from the radiator plate (31); And a support member (34) that is mounted on the (10) and supports the radiating plate (31) and the fin (32). The support member (34) has a terminal (2).
0b) and an insulating plate (34d) made of an insulating material disposed between the groove (31a) of the heat radiating plate (31) and the groove (31a).

Thus, the insulating plate (34d) disposed between the terminal (20b) and the groove (31a) of the heat radiating plate (31) is integrally formed with the support member (34). As a means for reducing the width of the groove (31a) for preventing discharge between the heat dissipation plate (31) and the heat dissipation plate (31), as compared with a conventional means for attaching an insulating sheet (40) to the heat dissipation plate (31). Thus, an increase in the number of parts and an increase in the number of assembling steps can be suppressed.

In the case where the fins (32) are corrugated fins, the portion corresponding to the groove (31a) of the heat radiation plate (31) and the corrugated fins (32). In this case, the width of the groove (31a) must be reduced. Therefore, the invention according to claim 2 is preferably used when the fin (32) is a corrugated fin.

According to the fourth aspect of the present invention, the electronic component (20) is screwed to the heat radiating plate (31), and the insulating plate (34d) is connected to the main body of the electronic component (20). (20a) has an end surface (34f) extending along at least one side.

Thus, when the electronic component (20) is rotated together with the screw when the electronic component (20) is screwed, the end face (34) of the insulating plate (34d) is rotated.
f) is in contact with one side of the body (20a) of the electronic component (20), so that the insulating plate (34d) is connected to the electronic component (20).
Can function as a detent.

According to the fifth aspect of the present invention, the support member (34) extends substantially perpendicularly to the substrate (10), and one end of the support member (34) is assembled to the substrate (10). ), And the plurality of legs (34a) are connected by an insulating plate (34d).
d) has an opening (34e), and the main body (20a) of the electronic component (20) is located in the opening (34e).

The reference numerals in parentheses of the above means are examples showing the correspondence with specific means described in the embodiments described later.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In this embodiment, a power transistor mounted on a control circuit board of an electromagnetic rice cooker and other home electric appliances is used as an electronic component that generates heat according to the present invention, and an electronic component that cools the power transistor is used. The cooling device of the present invention is applied to a cooling device (hereinafter, abbreviated as a cooling device). FIG. 1 is a front view showing a state in which two power transistors 20 are mounted on a substrate 10 and one cooling device 30 is assembled. FIG. 2 is a view taken in the direction of arrow A in FIG. FIG. 2 is a view as viewed in the direction of arrow B in FIG.

The substrate 10 is a printed wiring board on which an electric circuit (not shown) is printed at least on a surface (lower surface) opposite to the power transistor 20. And
A plurality of pin-shaped terminals 20b extending from one side surface of the body 20a of the power transistor 20 toward the substrate 10
Are inserted into through holes of the substrate 10 and soldered to an electric circuit formed on the lower surface of the substrate 10. As shown in FIG. 3, the two power transistors 20 are arranged side by side such that their terminals 20b are arranged in a straight line.

Next, the cooling device 30 will be described.

The cooling device 30 includes the power transistor 20
A radiating plate 31 joined to an upper surface of the fin, a corrugated fin (hereinafter abbreviated as a fin) 32 thermally joined to a surface (upper surface) of the radiating plate 31 opposite to the power transistor 20. 32 includes a box fan 33 arranged on the side opposite to the heat radiating plate 31, and a supporting member 34 attached to the substrate 10 and supporting the heat radiating plate 31, the fin 32, and the box fan 33.

The heat radiating plate 31 is formed in a plate shape from a non-ferrous metal such as aluminum, and is formed in a substantially cross shape in which four corners of a square are cut off as shown in FIG. The two power transistors 20 are joined to substantially the center of the lower surface of the heat dissipation plate 31 via heat conduction grease (for example, silicon grease) (not shown). In this embodiment, one screw 21 (for example, M3 screw) is used.
As a result, the power transistor 20 is fixed to the heat dissipation plate 31 and thermally joined.

When the power transistor 20 is driven, a voltage of 600 to 700 V is applied. Therefore, in order to prevent the power from being discharged from the terminal 20b to the heat radiating plate 31, the lower surface of the heat radiating plate 31 is A groove 31a extending in a direction perpendicular to the plane of FIG. 1 is formed in a portion of the power transistor 20 facing the terminal 20b. The groove 31a extends the distance between the terminal 20b and the heat dissipation plate 31 to prevent discharge.

In addition, irrespective of the variation in the assembling position of the power transistor 20 with respect to the heat radiating plate 31 (assembly tolerance), the groove 31a is surely located above the portion of the terminal 20b near the transistor body 20a. Need to be kept. Therefore, one side surface of the groove 31a (the surface indicated by reference numeral 31b in FIG. 3) is located closer to the transistor body 20a than the terminal 20b (the right side in FIG. 3). Then, the other side surface of the groove 31a (reference numeral 31c in FIG. 3)
Surface) is an opening 34 of an insulating plate 34d described later.
It is located on the opposite side (left side in FIG. 3) of the transistor body 20a than e.

In this embodiment, the width L1 of the groove 31a is about 5 m
m, and the approximate center in the width direction of the groove 31a is located directly above the surface on which the terminal 20b extends among the side surfaces of the transistor body 20a. In the present embodiment, the groove 3
The depth L2 of 1a is set to about 1.5 mm, and the dimension of the depth L2 is set so as to keep a distance from the terminal 20b to the heat radiation plate 31 so as not to discharge.

The fins 32 are corrugated fins for promoting heat radiation from the heat radiation plate 31 by roller-forming a thin aluminum plate into a wave shape.
As shown in FIG. 2, a number of well-known louvers 32a for turning the air flow in a predetermined direction are formed. The fins 32 are joined to the heat radiating plate 31 by well-known ultrasonic joining. That is, the fins 32 are vibrated and joined to the heat radiation plate 31 fixed by the jig while pressing the fins 32.

The box fan 33 includes the heat radiating plate 31
The fan 33 is an axial-flow type blower that blows out cooling air from a direction substantially perpendicular to the plate surface toward the heat-dissipating plate 31. The box fan 33 includes an axial fan (not shown) in a rectangular parallelepiped box 33a. It is a well-known type housing a small electric motor that drives this axial fan.

The support member 34 is formed of resin (for example, nylon 6), and has four columnar legs 34a extending substantially perpendicular to the substrate 10. These legs 34a are located at four corner cutouts of the heat radiation plate 31, and one end of the legs 34a is assembled to the substrate 10. In the present embodiment, a screw insertion hole NA formed at one end (lower end) of the leg 34a is fixed from below the substrate 10 with a screw N and assembled.

At the other end (upper end) of the leg portion 34a, a columnar fan locking portion 34b extending upward is formed, and the tip of the fan locking portion 34b projects radially outward. A claw 34c is formed, and this claw 34c is elastically deformable radially inward. Here, box 33
The four insertion holes 33b are formed at the four corners of the vertical axis a so that the claws 34c are elastically deformed.
Until the fan lock portion 34b is inserted through the insertion hole 33b.
To be inserted. As a result, the box 33a is
The box fan 33 is supported by being sandwiched between the lower surface of 4c and the upper surface of the leg portion 34a.

The support member 34 has four legs 34a.
Are integrally formed. That is, the insulating plate 34 is a substantially square with the outer circumferences of the four legs 34 a of the support member 34 as four corners,
It is formed substantially parallel to the substrate 10. The insulating plate 34d is connected to the terminal 20b and the groove 31a of the heat radiation plate 31.
It is located between.

Further, as shown in FIG.
4d, body 20a of two power transistors 20
Corresponding to the transistor body 20
An opening 34e having a shape slightly larger than the outer shape of a is formed, and the transistor main body 20a is located in the opening 34e of the insulating plate 34d.
Therefore, there is a minute gap CL between the outer periphery of the transistor body 20a and the inner periphery of the opening 34e of the insulating plate 34d.

The size of the minute gap CL is set so as to be able to absorb variations in the assembly position of the power transistor 20 with respect to the heat radiating plate 31 (assembly tolerance), dimensional tolerances due to resin molding of the insulating plate 34d, and the like. Yes,
In the present embodiment, the minute gap CL is set to about 0.5 mm.

The plate thickness L3 of the insulating plate 34d is
The size is set to a size necessary to reliably insulate between the terminal 20b and the heat radiation plate 31. In addition, the strength is set so that the insulating plate 34d has a strength necessary for exhibiting the function of preventing the transistor 20 from rotating as described later.
In view of these points, the thickness L3 of the insulating plate 34d is 5
mm or more is preferable.

In addition, at the four positions (see FIG. 3) of the upper side surface of the insulating plate 34d which are located between two adjacent leg portions 34a, a cylindrical heat-radiating plate locking portion extending upward. 34g is formed, and a claw 34h protruding radially outward is formed at the tip of the heat-radiating plate locking portion 34g, and the claw 34h is elastically deformable radially inward. Here, an insertion hole 31d penetrating vertically is formed at a position of the heat radiation plate 31 corresponding to the heat radiation plate locking portion 34g, and the claw 34h is elastically deformed until it penetrates the insertion hole 31d. The heat radiation plate locking portion 34g is inserted into the insertion hole 31d. Thereby, the heat radiation plate 31 is sandwiched between the lower surface of the claw 34h and the upper surface of the insulating plate 34d,
1 is supported.

Next, the procedure for assembling the cooling device 30 will be described.

First, the corrugated fin 32 and the heat radiating plate 31 are joined by ultrasonic joining. After that, the locking portion 34 g for the heat radiation plate of the support member 34 and the claw 34
h, the heat radiation plate 31 is assembled to the support member 34. Thereafter, the box fan 33 is assembled to the support member 34 by the fan locking portion 34b and the claw 34c of the support member 34. After that, the power transistor 20 is attached to the heat dissipation plate 31 by the screw 21. After that, the support member 34 is assembled to the substrate 10 with the screw N. Thereafter, the terminal 20b of the power transistor 20 is soldered to an electric circuit formed on the substrate 10.

Next, the features of this embodiment having the above configuration will be described.

As described above, the insulating plate 34d disposed between the terminal 20b and the groove 31a of the heat radiating plate 31
Is integrally formed with the leg portion 34a of the support member 34, so that the conventional insulating sheet 40 is radiated as a means for reducing the width of the groove 31a for preventing discharge between the terminal 20b and the heat radiation plate 31. Compared with the means for attaching to the plate 31, an increase in the number of parts and an increase in the number of assembling steps can be suppressed.

Further, since the transistor body 20a is arranged in the opening 34e of the insulating plate 34d with the minute gap CL interposed therebetween, the power transistor 20 rotates together with the screw N when screwing the power transistor 20. Even if you do, the insulating plate 3
The end face 34f of the opening 34d of the 4d is
a, the insulating plate 34 d can function as a detent for the transistor 20.

(Other Embodiments) In the above embodiment, the insulating plate 34 is provided with the four legs 34 of the support member 34.
a are connected to each other, but the present invention is not limited to this, and it is sufficient that the insulating plate 34 is disposed between the terminal 20b and the heat radiating plate 31. For example, the left side of FIG. Only the two legs 34a may be connected. In this case, if the insulating plate 34d is formed with an end surface 34f (see reference numeral 34f in FIG. 1) extending along the surface on which the terminal 20b extends among the side surfaces of the transistor body 20a, the rotation of the power transistor 20 is prevented. The insulating plate 34d can also serve the function, which is preferable.

In the above-described embodiment, corrugated fins are used as the fins 32 that are thermally joined to the heat radiating plate 31. However, the fins 32 are not limited to corrugated fins. Fins (heat sinks) may be used. Further, the heat radiating plate 31 and the fin 32 only need to be thermally joined, and the heat radiating plate 31 and the heat sink 32 may be integrally molded.

In the above-described embodiment, the heat radiation plate 31 has a rectangular shape, but the present invention is not limited to this, and may have another shape such as a circle.

The electronic component cooling device of the present invention is not limited to a device for cooling a power transistor, but may be a device for cooling an IC and other electronic components that generate heat.

In the above-described embodiment, the present invention is applied to the power transistor mounted on the control circuit board of the home electric appliance. Of course, the present invention can be applied to a power transistor mounted on a substrate of an electric device.

[Brief description of the drawings]

FIG. 1 is a front view showing a cooling device according to an embodiment of the present invention.

FIG. 2 is a view taken in the direction of arrow A in FIG. 1;

FIG. 3 is a view taken in the direction of arrow B in FIG. 1;

FIG. 4A is a front view showing a conventional cooling device,
(B) is a view on arrow C, and (c) is a view on arrow D.

[Explanation of symbols]

10: printed wiring board, 20: power transistor,
20b: terminal, 31: heat dissipation plate, 31a: groove, 32
... corrugated fins, 34 ... support members, 34a ... legs,
34d: insulating plate; 34e: opening.

Claims (5)

[Claims] An electronic component cooling device that cools an electronic component (20) that is mounted on a substrate (10) on which an electric circuit is formed and generates heat, wherein the substrate (10) of the electronic component (20) is cooled. A radiating plate (31) joined to the surface on the opposite side to radiate heat from the electronic component (20); and a support assembled to the substrate (10) and supporting the radiating plate (31). A member (34), wherein the supporting member (34) includes an insulating plate (34d) made of an insulating material disposed between the terminal (20b) of the electronic component (20) and the heat dissipation plate (31). ) Is integrally formed with the electronic component cooling device. 2. An electronic component cooling device for cooling an electronic component (20) that is mounted on a substrate (10) on which an electric circuit is formed and generates heat, wherein the substrate (10) of the electronic component (20) is cooled. Plate (3) having a groove (31a) at a portion facing the terminal (20b) of the electronic component (20).
1) and the electronic component (20) of the heat dissipation plate (31)
Is thermally bonded to the surface on the side opposite to the heat dissipation plate (3).
A fin (32) for promoting heat radiation from 1); and a support member (34) attached to the substrate (10) and supporting the radiator plate (31) and the fin (32). The support member (34) is integrally formed with an insulating plate (34d) made of an insulating material disposed between the terminal (20b) and the groove (31a) of the heat radiating plate (31). Electronic component cooling device. 3. The cooling device according to claim 2, wherein the fins are corrugated fins. 4. The electronic component (20) is adapted to be screwed to the heat radiating plate (31), and the insulating plate (34d) is fixed to the electronic component (20).
4. An end face (34f) extending along at least one side of said body (20a).
The electronic component cooling device according to any one of the above. 5. The support member (34) is provided on the substrate (1).
0) extending substantially perpendicular to the substrate (1).
0), a plurality of legs (34a) assembled to the insulating plate (34).
The insulating plate (34d) has an opening (34e), and the main body (20a) of the electronic component (20) is located in the opening (34e). Item 5. An electronic component cooling device according to any one of Items 1 to 4.