JPH09172112A - Heat dissipation device for heat generating element - Google Patents

Abstract

(57) [Abstract] [PROBLEMS] By projecting a heat dissipation plate provided on a heat conduction plate of a heat dissipation member to the outside, heat from a heat-generating element can be reliably dissipated to the outside and heat dissipation efficiency is improved. The area of the radiator on the substrate can be reduced, and the overall size can be reduced. SOLUTION: A heat sink 24 composed of a heat conduction plate 25 and each heat radiation plate 28 is arranged on a substrate 22 fixed to a support base 21 via an adhesive layer 23. And each heat sink 2
8 is the through holes 22A, 21 of the substrate 22 and the support base 21.
The heat conductive plate 25 is attached to the solder layer 2 in a state of protruding from A to the outside.
It is fixed on the substrate 22 via 6. In addition, the heat conduction plate 25
The transistor 6 is fixed on the upper side of the solder layer 27.
Then, the source 8 and the gate 9 of the transistor 6 are connected to each wiring pattern on the substrate 22 via the bonding wires 29 and 30, and the drain 10 is connected to the wiring pattern on the substrate 22 via the heat conduction plate 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-dissipating device heat-dissipating apparatus which is suitable for radiating heat generated from a heat-generating element such as a power transistor to the outside.

[0002]

2. Description of the Related Art As a heat dissipation device for a heat generating element according to the prior art, a heat dissipation device for a bare chip type field effect transistor will be described as an example with reference to FIG.

In the figure, reference numeral 1 denotes a support base composed of, for example, a casing of a control unit. The support base 1 is made of, for example, aluminum, a resin material or the like in a flat plate shape, and the back side of the support base 1 (see FIG. The lower surface side in 3) is the outer surface 1A of the control unit or the like.

Reference numeral 2 denotes a substrate on which a transistor 6 to be described later is mounted. The substrate 2 is made of, for example, aluminum oxide (Al ₂
The support base 1 is formed in a flat plate shape from a ceramic material such as O ₃ ) and has an adhesive layer 3 made of an adhesive having a high thermal conductivity.
Fixed on top. Further, on the substrate 2, there are three wiring patterns (not shown) connected to the source 8, the gate 9 and the drain 10 of the transistor 6 described later.
Are formed.

Reference numeral 4 denotes a heat spreader as a radiator fixed to the substrate 2 via a solder layer 5. The heat spreader 4 is made of a material having high thermal conductivity, such as copper (Cu),
It is formed of a metal material such as molybdenum (Mo) as a rectangular flat plate having an outer dimension of about 10 mm square and a thickness dimension of about 1 to 1.5 mm. Here, the heat spreader 4 has a sufficiently large area according to the amount of heat generated by the transistor 6, so that heat generated while the transistor 6 is energized is effectively radiated (conducted) to the substrate 2 side.

Reference numeral 6 denotes a transistor as a heat generating element, and the transistor 6 is, for example, a bare chip type field effect transistor (FET) having a square shape of about 5 mm square.
As a heat spreader 4 via the solder layer 7
It is fixed to the upper center. And the transistor 6
Of the input / output terminals, the source 8 side terminal and the gate 9 side terminal are formed apart from each other on the front surface of the transistor 6, and the drain 10 side terminal is formed on the back surface side of the transistor 6. The drain 10 side terminal is connected to the wiring pattern formed on the substrate 2 via the heat spreader 4 and the solder layers 5 and 7.

Reference numerals 11 and 12 are bonding wires. The bonding wires 11 and 12 are fixed to the source 8 side terminal and the gate 9 side terminal of the transistor 6 at the base end side through the aluminum pads 13, and the tip end side is made to each aluminum. It is fixed to other wiring patterns formed on the substrate 2 via the pads 14. The middle portions of the bonding wires 11 and 12 are arranged with a large slack in a substantially arc shape, whereby the bonding wires 11 and 12 are separated from the heat spreader 4 conducted to the drain 10 of the transistor 6 and the source 8 is formed. , The gate 9 and each wiring pattern on the substrate 2 are connected.

In the conventional technology thus constructed, when a voltage signal is input from the wiring pattern on the substrate 2 to the gate 9 of the transistor 6 via the bonding wire 12 or the like, the source 8 of the transistor 6 is generated in response to the voltage signal. ，
Since the drains 10 are electrically connected, the drain 10
A large current flows from the wiring pattern on the substrate 2 connected to the side to the wiring pattern on the source 8 side via the heat spreader 4, the transistor 6, the bonding wire 11, and the like.

Since a large current flows between the source 8 and the drain 10, the transistor 6 is heated during energization (during operation), and this heat is conducted to the substrate 2 via the heat spreader 4, and the heat is further transmitted. By being conducted from the substrate 2 to the support 1, the support 1 is radiated to the outside.

As a result, according to the conventional technique, the heat generated while the transistor 6 is energized heats the heat spreader 4 and the substrate 2.
And by radiating heat to the outside through the support base 1 etc.,
The temperature of the transistor 6 is, for example, 100 ° C. which is lower than the endurance temperature
The transistor 6 is kept at a certain level to prevent the transistor 6 from being damaged due to high temperature during energization.

[0011]

By the way, in the above-mentioned prior art, the heat generated from the transistor 6 is conducted to the heat spreader 4 via the solder layer 7, and the heat spreader 4 to the substrate 2 via the solder layer 5. To the support base 1 through the adhesive layer 3 from the substrate 2, and finally the heat is radiated from the support base 1 to the outside.

Here, the solder layers 5 and 7 and the adhesive layer 3 are
It is formed by solidifying liquid solder, adhesive or the like applied between the transistor 6, the heat spreader 4, the substrate 2 and the support 1 in the assembly process of the heat dissipation device. For example, in the adhesive layer 3, the substrate 2 and the support 2 are formed. By applying a liquid adhesive or the like between the two and the two, but abutting them, the solidified adhesive forms an adhesive layer 3, whereby the substrate 2 and the support base 1 interpose the adhesive layer 3 therebetween. It is glued.

However, in the above-mentioned bonding process, the substrate 2
Air may be mixed in the adhesive applied at the stage of abutting the support base 1 with the support base 1 to form air bubbles inside the adhesive layer 3, and air bubbles having poor thermal conductivity (air etc.) may be formed inside the adhesive layer 3. (3) is formed, there is a problem that not only the thermal conductivity between the substrate 2 and the support 1 is deteriorated but also the thermal conductivity varies among the heat dissipation devices.

Further, since bubbles may be similarly formed inside the solder layers 5 and 7, in the prior art, the transistor 6, the heat spreader 4, the substrate 2 and the support base 1 are used.
The thermal conductivity between the respective abutting surfaces of the transistor 6 is deteriorated by bubbles and the like, and the heat from the transistor 6 is less likely to be released to the outside, and the transistor 6 becomes hot during energization and is damaged, or is deteriorated early by heat. There is a problem that.

In particular, when the support base 1 is made of a resin material having a low thermal conductivity, a high thermal conductivity is required between the transistor 6 and the support base 1, so that air bubbles or the like cause a gap between them. If the heat dissipation property is hindered, the transistor 6 is likely to have a higher temperature during energization, and there is a high possibility of causing problems such as damage and deterioration.

Further, since the heat conductivity from the transistor 6 to the support 1 varies depending on the heat dissipation device, in order to ensure the reliability of the transistor 6, the area of the heat spreader 4 should be designed large at the design stage. As a result, there is no choice but to have a margin for the heat radiation performance from the transistor 6 to the support 1, and it is difficult to reduce the size of the entire heat radiation device.

The present invention has been made in view of the above-mentioned problems of the prior art, and can surely radiate the heat from the heat-generating element to the outside without varying the thermal conductivity of each heat radiating device, and at the same time, dissipate the heat on the substrate. It is an object of the present invention to provide a heat-dissipating device heat-dissipating device capable of reducing the area and reducing the size of the entire device.

[0018]

In order to solve the above-mentioned problems, the invention according to claim 1 is to provide a substrate provided on a support base, and a radiator made of a heat conductive material provided on the substrate. A heat-dissipating device for heat-generating elements, which is provided on the heat-dissipating body so that heat can be conducted, and which generates heat by energization from the outside, wherein the heat-dissipating body is composed of the substrate and the heat-generating element. The heat conducting plate is disposed between the heat conducting plate and the heat conducting plate, the base side of which is integrally connected to the heat conducting plate and the tip side of which is a heat radiating plate protruding to the outside of the support through the substrate and the support. It is characterized by

According to this structure, the heat generated by the heat-generating element provided on the radiator is conducted from the heat conducting plate of the radiator to the radiator side, and the tip side of the radiator plate is conducted. The heat from the heat generating element can be radiated to the outside without being affected by the thermal conductivity of the substrate, the support, etc., since the heat can be directly radiated from the heat generating element to the outside of the supporting table, and the heat generating element becomes high temperature during energization. Can be prevented.

According to the second aspect of the invention, the radiator is formed in a substantially U-shaped cross section, and the radiator plates are provided on both ends of the heat conducting plate.

With this, heat from the heat-generating element can be efficiently conducted from both ends of the heat conducting plate to each heat radiating plate side, and this heat is transmitted from the tip end side of each heat radiating plate to the outside of the support base. With a large heat dissipation area, it can dissipate heat.

In the invention according to claim 3, the heat generating element is composed of a power system bare chip for high voltage or high current, and the radiator dissipates heat from the bare chip to the outside of the support base. I am trying.

As a result, the heat generated by the power bare chip during conduction is conducted from the heat conducting plate of the radiator to the radiator plate side, and the tip side of the radiator plate can be efficiently radiated to the outside of the support base. The temperature rise of the bare chip can be suppressed.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the accompanying drawings, taking as an example a case where a bare chip type field effect transistor is used as a heat generating element. In the embodiments, the same components as those in the related art are denoted by the same reference numerals, and description thereof will be omitted.

In the figure, reference numeral 21 denotes a support base of the heat dissipation device according to this embodiment. The support base 21 is formed in a flat plate shape from, for example, aluminum or a resin material as in the prior art, and the transistor 6 is formed on the surface thereof. Although the substrate 22 similar to that of the related art, which is mounted with the like, is fixed via the adhesive layer 23,
In this embodiment, each heat radiating plate 2 of the heat sink 24 described later is used.
Insertion holes 21A and 21A for inserting the through holes 8 are formed in the support base 21, and insertion holes 22A and 22A are formed in the substrate 22.

Here, as shown in FIG. 2, each of the through holes 21A is a slit-shaped through hole which is separated from each other, and thus the support base 2 is provided.
1 is formed, and each insertion hole 22A is formed in each insertion hole 2
It is formed in the substrate 22 as a through hole corresponding to the position of 1A. When the substrate 22 is fixed on the support 21, the insertion holes 21A and 22A communicate with each other, whereby the support 21 and the substrate 22 have a front surface side of the substrate 22 and a rear surface side of the support 21. A pair of through holes communicating with the (outer side surface) is formed.

Reference numeral 24 denotes a heat sink as a radiator according to the present embodiment. The heat sink 24 is made of a material having high thermal conductivity, for example, a metal material such as copper (Cu) or molybdenum (Mo) and has a U-shaped cross section. The heat conducting plate 25 described later
And heat radiating plates 28, 28 which will be described later and are integrally formed on both ends of the heat conducting plate 25.

Reference numeral 25 denotes a heat conducting plate, which is formed as a rectangular flat plate as shown in FIG. 2 like the heat spreader 4 according to the prior art, but the heat conducting plate 25 according to the present embodiment. Has an outer dimension smaller than that of the heat spreader 4. Then, the heat conduction plate 25 is fixed onto the substrate 22 via the solder layer 26,
Thereby, the heat sink 24 is fixed on the substrate 22. Further, as shown in FIG. 1, the transistor 6 is fixed on the heat conduction plate 25 via the solder layer 27, and the drain 10 side terminal formed on the back surface side of the transistor 6 is
It is connected to a wiring pattern (not shown) for drain connection formed on the substrate 22 via the solder layer 27, the heat conduction plate 25, and the solder layer 26.

Reference numerals 28 and 28 denote heat radiating plates, and the respective heat radiating plates 2
Reference numerals 8 are integrally formed on both end sides of a heat conduction plate 25 having base ends fixed to the substrate 22, and extend vertically downward in parallel to each other as shown in FIG. And each heat sink 2
The front end side 28A of 8 is sequentially inserted into the respective insertion holes 22A of the substrate 22 and the respective insertion holes 21A of the support base 21 so as to be provided so as to project to the outside from the back surface side of the support base 21. .

29 and 30 are bonding wires made of a metal material such as aluminum. The bonding wires 29 and 30 are the source 8 and the gate 9 of the transistor 6 and the source formed on the substrate 22 as in the prior art. 8 and a wiring pattern for connecting the gate 9 (neither is shown) are connected via the aluminum pads 31 and 32. However, in the present embodiment, the outer dimensions of the heat conduction plate 25 are smaller than those of the heat spreader 4, and the aluminum pad 31,
Since the connection distance between the wires 32 is shorter than that of the conventional technique, a relatively small slack is given to the middle portions of the bonding wires 29 and 30.

The connecting device according to the present embodiment has the above-mentioned structure, and its basic operation is not different from that of the prior art.

Therefore, in this embodiment, the heat sink 24 for radiating the heat from the transistor 6 to the outside is provided with the heat conducting plate 25 disposed between the transistor 6 and the substrate 22.
The base end side is integrally formed with the heat conduction plate 25, and the tip end side 28A
Is composed of the substrate 22 and a pair of heat radiating plates 28 penetrating the support 21 and protruding to the outside. Therefore, the heat generated while the transistor 6 is energized has a sufficient exposed area from the tip side 28A of each heat radiating plate 28. The heat can be efficiently radiated to the outside, and the heat radiation efficiency of the transistor 6 by the heat sink 24 can be significantly improved as compared with the conventional technique.

Therefore, even when the support base 21 is made of, for example, a resin material, it is possible to reliably prevent the transistor 6 from being damaged due to high heat during energization or being deteriorated at an early stage. The operating state can be maintained for a long period of time, and the reliability of the control device for controlling the current by the transistor 6 can be greatly improved.

Since the heat from the transistor 6 can be directly radiated to the outside through each heat radiating plate 28 of the heat sink 24, the heat conductive plate 25 and the substrate 22 of the heat sink 24 and the substrate 22 and the supporting base 21 are separated from each other. The heat from the transistor 6 can be surely radiated to the outside of the support 1 without being affected by the heat conductivity between them, and the variation in the heat conductivity from the transistor 6 to the support 1 can be effectively reduced. ,
The reliability of the heat dissipation device can be greatly improved.

Further, since the heat dissipation efficiency of the heat sink 24 can be improved by the respective heat dissipation plates 28 exposed to the outside of the support base 1, the outer dimensions of the heat conduction plate 25 can be formed smaller than the heat dissipation members such as the heat spreader 4 of the prior art. As a result, the heat sink 24 (heat conduction plate 25) can be easily arranged on the substrate 22, and the size of the entire heat dissipation device can be surely reduced.

By forming the heat conducting plate 25 small, the connection distance between the transistor 6 side and the wiring pattern on the substrate 22 by the bonding wires 29, 30 can be shortened, so that the bonding wires 29, 30 are bent. As a result, short circuit with the heat sink 24 can be reliably prevented, and the reliability thereof can be greatly improved.

Further, since the heat radiation path of the transistor 6 can be simplified by radiating the heat only through the heat sink 24, it is not necessary to specially consider the heat conductivity of the substrate 22, the support 21 and the like in the design. The design and manufacturing management of the heat dissipation device can be made efficient.

In the above embodiment, the pair of heat radiating plates 28 are used.
The heat sink 24 is formed in a U-shaped cross section by arranging the heat conducting plates 25 on both ends of the heat conducting plate 25. However, the present invention is not limited to this, and a heat radiating portion such as a heat radiating plate 28 may be provided between the transistor 6 and the substrate 22. The structure may be such that the heat conducting plate 25 arranged between them is projected to the outside of the support base 1. Therefore, for example, a heat sink (radiator) may be formed in a T-shape or E-shape in cross section from one or three heat dissipation plates and a heat conduction plate.
Further, the heat radiator may be configured by integrally providing four or more heat radiation plates or rod-shaped heat radiation portions (heat radiation plates) on the heat conduction plate 25.

Further, in the above embodiment, the case where the heat conducting plate 25 and each heat radiating plate 28 are integrally formed is described, but the present invention is not limited to this, and the heat conducting plate 25 and The heat sink 24 may be configured by forming each heat dissipation plate 28 from a separate member and integrally connecting them.

On the other hand, in the above embodiment, the source 8 side terminal and the gate 9 side terminal are arranged on the front surface side of the transistor 6, and the drain 10 side terminal is arranged on the rear surface side, but the present invention is not limited to this. For example, the drain 10 side terminal may be arranged on the front surface side of the transistor 6, and the source 8 side terminal may be arranged on the back surface side of the transistor 6. In this case, the drain 10 side terminal is bonded to the bonding wire 29.
The source 8 side terminal may be connected to another wiring pattern on the substrate 22 via the heat conduction plate 25 of the heat sink 24 or the like.

Further, in the above embodiment, the case where the bare chip type field effect transistor is used as the heat generating element has been described as an example, but the present invention is not limited to this, and is applied to other power transistors and the like. Alternatively, it may be applied to power electronic devices other than transistors, such as thyristors and three-terminal regulators.

Furthermore, in the above embodiment, the case where a single heat generating element (transistor 6) is arranged on the heat conducting plate 25 of the heat sink 24 has been described as an example, but the present invention is not limited to this. Instead, it may be applied to a heat dissipation device for a heat generating element in which a plurality of heat generating elements are arranged on the heat conducting plate 25.

[0043]

As described above in detail, according to the first aspect of the invention, the heat radiator is provided with the heat conducting plate disposed between the heat generating element and the substrate, and the heat conduction plate is provided at the base end side. Since it is formed integrally with the plate, and the tip side is composed of the substrate and the heat radiating plate protruding to the outside of the support via the support, the heat generated while the heat-generating element is energized is transferred from the tip of the heat radiating plate to the outside. It is possible to efficiently dissipate heat, and it is possible to reliably prevent the heat generating element from becoming high in heat while being energized and being damaged, or from being deteriorated early. Further, the heat from the heat-generating element can be directly radiated to the outside of the support through the heat dissipation plate, so that the heat from the heat-generating element can be reliably radiated without being affected by the thermal conductivity of the substrate, the support or the like. At the same time, it is possible to effectively reduce the variation in the thermal conductivity from the heat-generating element to the support, and it is possible to significantly improve the reliability of the heat dissipation device.

Further, according to the second aspect of the invention, since the heat radiator is formed in a substantially U-shaped cross section by the heat conducting plate and the pair of heat radiating plates, the heat from the heat generating element is transferred to the heat conducting plate. The heat can be efficiently conducted from both ends to each heat dissipation plate side, and this heat can be reliably dissipated from the tip side of each heat dissipation plate to the outside of the support with a wide heat dissipation area, and the temperature rise of the heat generating element. Can be effectively suppressed.

According to the invention described in claim 3,
Since the heat-generating element is composed of the power bare chip and the heat from the bare chip is radiated to the outside by the radiator, the heat generated by the radiator plate of the radiator while the bare chip is energized is transferred to the outside of the support base. It is possible to effectively dissipate heat, and it is possible to reliably prevent the temperature of the bare chip from rising during energization.

[Brief description of the drawings]

FIG. 1 is a vertical cross-sectional view showing a heat dissipation device for a field effect transistor according to an embodiment of the present invention.

FIG. 2 is a plan view showing a heat dissipation device for the field effect transistor in FIG.

FIG. 3 is a vertical cross-sectional view showing a heat dissipation device for a field effect transistor according to a conventional technique.

[Explanation of symbols]

 6 Transistor (Exothermic Element) 8 Source 9 Gate 10 Drain 21 Support 22 Substrate 24 Heat Sink (Heat Radiator) 25 Heat Conduction Plate 28 Heat Radiation Plate

Claims (3)

[Claims] 1. A substrate provided on a support, a heat radiator made of a heat conductive material provided on the substrate, and heat radiator provided on the heat radiator so as to generate heat by energization from the outside. In the heat dissipation device for a heat-generating element including a heat-generating element, the heat-dissipating body includes a heat-conducting plate disposed between the substrate and the heat-generating element, and a base end side of the heat-conducting plate is integrated with the heat-conducting plate. A heat dissipation device for a heat-generating element, characterized in that the heat dissipation element is connected to the front end side of the substrate and the heat dissipation plate protruding to the outside of the support base through the support base. 2. The heat dissipating device for a heat-generating element according to claim 1, wherein the heat dissipating member is formed in a substantially U-shaped cross section, and the heat dissipating plates are respectively provided on both ends of the heat conducting plate. 3. The heat-generating element comprises a power system bare chip for high voltage or high current, and the radiator dissipates heat from the bare chip to the outside of the support base. A heat dissipation device for the heat-generating element described.