JP2005191378A - Heat radiation structure in printed board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat radiation structure with less restrictions at the time of arranging components while miniaturizing a printed board. <P>SOLUTION: Wiring patterns 11a and 11b are formed on the surface layer (front) 11 of the printed board 1, and a wiring pattern 12a is formed on an inner layer 12. A heat generating component 2 is electrically connected to the wiring pattern 11a. A screw 31 fixes the printed board 1 to a case body 32 while being in contact with the wiring pattern 11b. Heat generated in the heat generating component 2 is transmitted through the wiring pattern 11a, the wiring pattern 12a, the wiring pattern 11b and the screw 31 to the case body 32. The heat is transferred between the wiring patterns through an insulating layer. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a heat dissipation structure in a multilayer printed board on which components constituting an electric circuit or an electronic circuit are mounted.

  Various electric circuits or electronic circuits are usually mounted on a printed circuit board. At this time, depending on a circuit to be mounted, a component that allows a large current to flow may be mounted. In this case, a component (for example, a fuse, a large resistor, a power transistor, etc.) through which a large current flows is often a heating element. In the following, a component that becomes a heating element may be referred to as a “heating component”.

  On the other hand, on the printed board, there are many cases where components such as ICs that are vulnerable to high temperatures (or components in which the surroundings are not preferably high) are mounted. For this reason, when the above heat generating components and components vulnerable to high temperatures are mixed on the printed circuit board, measures to protect the components vulnerable to high temperatures are required.

The simplest way to protect parts that are sensitive to high temperatures is to design the arrangement of the parts so that the distance from the heat-generating parts is large.
Further, as shown in FIG. 5, a heat transfer plate 103 is attached to the heat generating component 102 on the printed circuit board 101, and the heat generated by the heat generating component 102 is brought into contact with a heat sink 104 such as a heat sink. The structure which protects the components 105 which are weak to high temperature by escaping to the outside is also implemented.

Furthermore, Patent Document 1 describes a structure in which heat generated from a heat generating component mounted on a printed board is released from the back cover to the outside through a heat radiation pattern and a nut.
Further, in Patent Document 2, in a configuration in which a heat dissipation component is provided on one surface of a printed circuit board and a heat dissipation plate is provided on the other surface through an insulating sheet, both surfaces of the substrate are thermally connected by through vias. The structure is described.
Japanese Patent Laid-Open No. 9-32467 (FIG. 1, paragraphs 0011 to 0016) Japanese Patent Laid-Open No. 2002-94274 (FIGS. 1 to 4, paragraphs 0006 to 0009)

  Of the known techniques described above, it is difficult to reduce the size of the printed circuit board with a structure that increases the distance from the heat-generating component to a component that is vulnerable to high temperatures. Further, as shown in FIG. 5, in the structure in which the heat generated in the heat generating component 102 is guided to the heat sink 104 such as a heat sink via the heat transfer plate 103, the heat transfer plate 103 and the heat sink 104 are required, and the number of components increases. In addition, a space for that is required.

  In the structure described in Patent Document 1, the insulating portion of the heat generating component is brought into contact with the heat radiation pattern. That is, it is necessary to form a pattern for heat dissipation separately from the wiring pattern. Moreover, in the structure described in Patent Document 2, dedicated parts for heat dissipation such as a heat sink and an insulating sheet are required.

  The present invention has been made in consideration of these problems, and an object of the present invention is to provide a heat dissipating structure with less restrictions on the arrangement of components while reducing the size of a printed circuit board.

  The heat dissipation structure of the present invention is premised on a printed circuit board having two or more layers on which wiring patterns are formed. And the heat-emitting component mounted in the said printed circuit board is electrically connected to the 1st wiring pattern currently formed in the 1st layer of the printed circuit board. In addition, the wiring patterns are formed so that heat transferred from the heat generating component to the first wiring pattern is transferred to the second wiring pattern formed on the second layer of the printed circuit board. . Then, the heat is released through the second wiring pattern.

In the above structure, heat generated in the heat generating component is transferred between the wiring patterns formed in different layers and released to the outside of the substrate.
In the above invention, the first wiring pattern and the second wiring pattern may be electrically insulated from each other. In this case, the heat generated in the heat generating component is released through a path in which a part thereof is electrically insulated.

  In the above invention, after the heat is transferred to the second wiring pattern, the heat is further released through a third wiring pattern formed in a layer other than the second layer. Also good. In this case, the heat generated in the heat generating component is successively transferred from the first wiring pattern to the second wiring pattern, and further from the second wiring pattern to the third wiring pattern.

Further, in the above invention, a fixing means for fixing the printed circuit board to the heat dissipation material may be provided so that the heat is transmitted to the heat dissipation material via the second wiring pattern and the fixing means. .
The heat dissipation structure according to another aspect of the present invention is premised on a printed circuit board having two or more layers on which a wiring pattern is formed, and a heat generating component mounted on the printed circuit board is formed on the first layer of the printed circuit board. It is electrically connected to the first wiring pattern. Further, a portion is formed in which heat transmitted from the heat generating component to the first wiring pattern overlaps with the second wiring pattern formed on the second layer of the printed circuit board. Then, the heat is released through the second wiring pattern. The operation of this heat dissipation structure is basically the same as that of the above-described heat dissipation structure.

  According to the present invention, the heat generated in the heat-generating component is transferred between the wiring patterns and released to the outside of the board. Therefore, it is only necessary to appropriately design the shape and arrangement of the wiring patterns for heat dissipation. The heat dissipation structure can be realized without providing any dedicated parts. Therefore, the printed circuit board can be reduced in size.

  In addition, since the wiring patterns for transferring heat are insulated, there is no need to form a dedicated heat radiation pattern for heat conduction described in Patent Document 1, and power is supplied to the heat-generating component. Alternatively, heat can be radiated using a wiring pattern electrically connected to the heat generating component for signal input / output.

  FIG. 1 is a diagram illustrating a heat dissipation structure according to an embodiment of the present invention. Here, an electric circuit / electronic circuit including the heat generating component 2 and the IC 3 is mounted on the printed circuit board 1. The heat generating component 2 is a component that can generate heat when a large current flows during the operation of the electric circuit / electronic circuit, and is not particularly limited. For example, the heat generating component 2 may be a fuse, a large resistor, a power transistor, or the like. Equivalent to. Further, the IC 3 is an example of a component that is vulnerable to high temperatures, and when the ambient temperature rises, the characteristics may be deteriorated or the IC 3 may be destroyed.

  The printed board 1 is a so-called four-layer board, and a wiring pattern is formed on each of the four layers. The four-layer substrate is formed, for example, by bonding two substrates each having a wiring pattern formed on both surfaces thereof. In this case, the front surface and the back surface of one substrate become the surface layer (front) 11 and the inner layer 12 of the printed circuit board 1, respectively. Further, the front surface and the back surface of the other substrate become a surface layer (back surface) 14 and an inner layer 13 of the printed circuit board 1, respectively. Note that the surfaces (that is, the inner layers 12 and 13) to which these two substrates are bonded are coated with, for example, an insulating resin and are electrically insulated from each other.

  On the surface layer (front) 11 of the printed circuit board 1, wiring patterns 11a and 11b are formed. Further, wiring patterns 14 a and 14 b are formed on the surface layer (back) 14 of the printed circuit board 1. Further, a wiring pattern 12 a is formed on the inner layer 12 of the printed circuit board 1, and a wiring pattern 13 a is formed on the inner layer 13. These wiring patterns are, for example, conductive patterns for transmitting signals of electric circuits / electronic circuits mounted on the printed circuit board 1 and / or conductive patterns for supplying electric power. Further, these wiring patterns are formed of a material having good electrical conductivity and thermal conductivity (for example, copper). Furthermore, the board itself constituting the printed board 1 is formed of an insulating material such as glass epoxy resin.

  Thus, an insulating layer (the above-described example) is provided between the wiring pattern (11a, 11b) formed on the surface layer (table) 11 of the printed circuit board 1 and the wiring pattern (12a) formed on the inner layer 12. Then, they are insulated from each other by the substrate 21). Similarly, between the wiring pattern (14a, 14b) formed on the surface layer (back) 14 of the printed circuit board 1 and the wiring pattern (13a) formed on the inner layer 13, an insulating layer (in the above example) The substrate itself is insulated from each other by 22.

  The heat generating component 2 is mounted such that the lead (terminal) 2 a penetrates the printed circuit board 1. Here, the lead 2 a is a terminal for inputting or outputting the main current of the heat generating component 2. The lead 2a is soldered to the wiring pattern 11a and the wiring pattern 14a. That is, the heat generating component 2 is electrically connected to the wiring pattern 11 a formed on the surface layer (front) 11 and the wiring pattern 14 a formed on the surface layer (back) 14. However, the heat generating component 2 is not connected to the wiring patterns 12 a and 13 a formed on the inner layer 12 or the inner layer 13.

  The printed circuit board 1 is fixed to a housing (heat dissipating material) 32 by screws (fixing means) 31. Here, it is assumed that the screw 31 is made of a material having good thermal conductivity. The screw 31 is in contact with the wiring pattern 11 b formed on the surface layer (front) 11. Further, the wiring pattern 14 b formed on the surface layer (back) 14 is pressed against the screw seat of the housing 23.

FIG. 2A is a diagram showing a mounting structure of the heat generating component 2. Here, the wiring pattern of each layer is schematically drawn in the cross-sectional view of the printed circuit board 1.
The printed circuit board 1 is provided with a hole for allowing the lead 2a of the heat generating component 2 to pass therethrough. Here, in the surface layer (front) 11 and the surface layer (back) 14, the wiring patterns 11 a and 14 a are formed up to the regions in contact with the holes, respectively. On the other hand, the inner layer 12 and the inner layer 13 are formed so that the lead 2a penetrates without contacting the wiring patterns 12a and 13a. Therefore, the lead 2a of the heat generating component 2 is electrically connected to the wiring patterns 11a and 14a, but is not connected to the wiring patterns 12a and 13a. It is assumed that the wiring patterns 11a and 12a and the wiring patterns 13a and 14a are electrically insulated from each other.

2A shows the connection relationship between the heat generating component 2 and the wiring patterns 11a to 14a, the connection relationship between the screw 31 and each of the wiring patterns 11b to 14b is basically the same. That is, the screw 31 is not in contact with the wiring patterns 12b and 13b.
FIG. 2B is a diagram illustrating the configuration of the wiring pattern, and schematically illustrates the printed circuit board 1 as viewed from above. Here, only the wiring pattern 11a formed on the surface layer (table) 11 and the wiring pattern 12a formed on the inner layer 12 are drawn.

  The wiring pattern 11 a is formed on the surface layer (front) 11 of the printed circuit board 1. On the other hand, the wiring pattern 12 a is formed on the inner layer 12 of the printed circuit board 1. Here, the wiring pattern 11a and the wiring pattern 12a are formed so that at least a part of these regions overlap each other. Although not shown, the wiring pattern 13a and the wiring pattern 14a are similarly formed so that at least a part of these regions overlap each other. Furthermore, the wiring pattern 11b and the wiring pattern 12a are also formed so that parts thereof overlap each other, and the wiring pattern 14b and the wiring pattern 13a are also formed so that parts thereof overlap each other.

Next, the heat radiation effect in the printed circuit board of the embodiment will be described with reference to FIG.
The heat generated in the heat generating component 2 is transmitted to the wiring patterns 11a and 14a through the leads 2a. Subsequently, the heat transferred to the wiring patterns 11a and 14a is transferred to the wiring patterns 12a and 13a formed in regions facing each other with the insulating layers 21 and 22 interposed therebetween, respectively. At this time, the insulating layer 21 exists between the wiring patterns 11a and 12a, and the insulating layer 22 exists between the wiring patterns 14a and 13a. However, the insulating layers 21 and 22 are not made of a heat insulating material. Moreover, the thickness is also 1 mm or less. Further, as shown in FIG. 2B, the areas where the wiring patterns 11a and 12a are formed overlap each other, and the areas where the wiring patterns 14a and 13a are formed overlap each other. Yes. Therefore, the heat transferred from the heat generating component 2 to the wiring patterns 11a and 14a is easily transferred to the wiring patterns 12a and 13a, respectively.

  The heat transferred to the wiring patterns 12a and 13a is transferred to the left direction on the paper surface of FIG. 1 and then transferred to the wiring patterns 11b and 14b, respectively. Here, the action of transferring heat from the wiring patterns 12a and 13a to the wiring patterns 11b and 14b is the same as the action of transferring heat from the wiring patterns 11a and 14a to the wiring patterns 12a and 13a. The heat transferred to the wiring pattern 11 b is transmitted to the housing 32 through the screw 31. Further, the heat transferred to the wiring pattern 14 b is directly transmitted to the housing 32.

  As described above, in the heat dissipation structure of the embodiment, the heat generated in the heat generating component is transferred between the wiring patterns via the insulating layer and transmitted to the housing as the heat dissipation material. Therefore, by appropriately designing the shape of the wiring pattern of each layer (specifically, a design in which wiring patterns to which heat is transferred overlap each other), a heat dissipation structure can be realized. That is, it is not necessary to provide dedicated parts for heat dissipation, which contributes to downsizing of the printed circuit board and reduction in the number of parts.

  Further, the heat dissipation structure of the embodiment does not directly reduce the temperature of the heat generating component itself, but can release the heat generated in the heat generating component to the heat radiating material so as not to be transmitted to a component that is vulnerable to high temperatures. Therefore, it becomes possible to arrange a heat-generating component and a component that is vulnerable to high temperatures adjacent to each other, and the degree of freedom of component arrangement is increased. In order to enhance this effect, for example, in FIG. 1, it is desirable that the wiring patterns 12a and 13a are not formed in the vicinity of the IC3.

  Furthermore, in the heat dissipation structure of the embodiment, heat generated in the heat generating component 2 is guided to the casing 32 as a heat dissipation material by passing heat between two or more electrically insulated wiring patterns. Therefore, a heat dissipation structure can be realized by using a wiring pattern (in the embodiment, wiring patterns 11a and 14a) electrically connected to the heat generating component 2 without short-circuiting the heat generating component 2 to the housing 32. That is, the degree of freedom in designing the printed circuit board 1 is increased.

In the example shown in FIG. 1, the lead 2a of the heat generating component 2 is electrically connected to both of the wiring patterns 11a and 14a, but may be connected to only one of the wiring patterns 11a and 14a. .
Further, in the example shown in FIG. 1, the lead 2 a of the heat generating component 2 is electrically connected to the wiring pattern formed on the surface layers 11 and 14, but the lead 2 a is formed on the surface layers 11 and 14. The same action also works when connected to the wiring pattern formed in the inner layers 12 and 13 without being connected to the existing wiring pattern. However, in this case, the heat transferred from the heat generating component 2 to the wiring pattern formed on the inner layers 12 and 13 is received by the wiring pattern formed on the surface layers 11 and 14 via the insulating layers 21 and 22. Passed and dissipated to the heat dissipation material.

  Furthermore, in the above-described embodiment, the heat generated in the heat generating component is transferred from the first wiring pattern (for example, the wiring pattern 11a) to the second wiring pattern (for example, the wiring pattern 12a), and the second wiring pattern. Are transferred to the third wiring pattern (for example, the wiring pattern 11b), but it is not necessary that all these wiring patterns are insulated from each other. For example, either the first wiring pattern and the second wiring pattern, or the second wiring pattern and the third wiring pattern are electrically connected through a through hole or a via hole. It may be.

  Note that the “first wiring pattern formed in the first layer” described in the claims is the wiring pattern 11a or the surface described in the surface layer (table) 11 in FIG. This corresponds to the wiring pattern 14 a formed on the layer (back) 14. Further, the “second wiring pattern formed in the second layer” corresponds to the wiring pattern 12 a described in the inner layer 12 or the wiring pattern 13 a formed in the inner layer 13 in FIG. 1. Further, the “third wiring pattern” corresponds to the wiring pattern 11b or the wiring pattern 14b.

FIG. 3 is a specific embodiment showing the effect of the present invention. In this example, the heat generating component 2 is a 3 W fuse, and the distance between the heat generating component 2 and the IC 3 is 39 mm.
When the heat dissipation structure of the present invention was not introduced, the ambient temperature of the IC 3 increased to 109.8 degrees as shown in FIG. On the other hand, as shown in FIG. 3B, when the screw 31 is provided in the vicinity of the heat generating component 2 and a structure for releasing the heat generated by the heat generating component from the screw 31 to the housing 32 is introduced, The ambient temperature was 103.6 degrees. That is, by introducing the heat dissipation structure of the present invention, the ambient temperature of the IC 3 was reduced by 6.2 degrees.

  The temperature difference of “6.2 degrees” is a large value when designing a printed circuit board. That is, for example, if the allowable upper limit temperature of the ambient temperature of the IC is 110 degrees, if the present invention is introduced, a sufficient margin can be obtained even if manufacturing variations are taken into consideration. On the other hand, if the present invention is not introduced, a sufficient margin cannot be obtained, and it may be necessary to change the component arrangement or use a dedicated heat dissipation component.

  In the embodiment shown in FIG. 1, the heat dissipation structure in the four-layer substrate is shown, but the present invention is not limited to this, and can be applied to a multilayer substrate having two or more layers. For example, FIG. 4 shows an embodiment in which the present invention is applied to a two-layer substrate. In this case, the heat generated in the heat generating component 2 is guided to the housing 32 via the lead 2a and the wiring pattern 14a, the wiring pattern 11b, and the screw 31. At this time, heat is transferred between the wiring patterns 14a and 11b via the insulating layer.

It is a figure explaining the heat dissipation structure of embodiment of this invention. (A) is a figure which shows the mounting structure of a heat-emitting component. (B) is a figure which shows the structure of a wiring pattern. It is a concrete Example which shows the effect of the present invention. It is an Example at the time of applying this invention to a two-layer board | substrate. It is a figure which shows an example of the conventional heat dissipation structure.

Explanation of symbols

1 Printed circuit board 2 Heat-generating components 3 IC (components sensitive to high temperatures)
11 Surface layer (table)
11a, 11b Wiring pattern 12, 13 Inner layer 12a, 13a Wiring pattern 14 Surface layer (back)
14a, 14b Wiring pattern 21, 22 Insulating layer 31 Screw 32 Housing

Claims (8)

A heat dissipation structure in a printed circuit board having two or more layers for forming a wiring pattern,
The heat generating component mounted on the printed circuit board is electrically connected to the first wiring pattern formed on the first layer of the printed circuit board,
The wiring patterns are formed so that heat transferred from the heat generating component to the first wiring pattern is transferred to the second wiring pattern formed on the second layer of the printed circuit board,
The heat dissipation structure in a printed circuit board, wherein the heat is released through the second wiring pattern. The heat dissipation structure in a printed circuit board according to claim 1, wherein the first wiring pattern and the second wiring pattern are electrically insulated from each other. The heat is transferred to the second wiring pattern and then released through a third wiring pattern formed in a layer other than the second layer. The heat dissipation structure in the printed circuit board according to claim 2. It further has a fixing means for fixing the printed circuit board to the heat dissipation material,
The heat dissipation structure in a printed circuit board according to any one of claims 1 to 3, wherein the heat is transmitted to the heat dissipation material via the second wiring pattern and the fixing means. A heat dissipation structure in a printed circuit board having two or more layers for forming a wiring pattern,
The heat generating component mounted on the printed circuit board is electrically connected to the first wiring pattern formed on the first layer of the printed circuit board,
A heat dissipation structure in a printed circuit board, wherein a portion where the first wiring pattern and the second wiring pattern formed in the second layer of the printed circuit board overlap is formed. The heat dissipation structure in the printed circuit board according to claim 5, wherein an insulating layer is provided between the first wiring pattern and the second wiring pattern. The portion where the second wiring pattern and a third wiring pattern formed in a layer other than the second layer are further formed is formed. Heat dissipation structure in printed circuit boards. It further has a fixing means for fixing the printed circuit board to the heat dissipation material,
The heat dissipation structure in a printed circuit board according to any one of claims 5 to 7, wherein the second wiring pattern and the fixing means are connected.

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