JP2012209309A - Electronic control device - Google Patents

Abstract

An electronic control device capable of improving heat dissipation efficiency is provided.
An electronic control device includes a printed circuit board (2) having an inner layer pattern (2e) formed in an inner layer and connected to a heat generating component (2f), and a casing (3) that accommodates the printed circuit board. It is an inner layer pattern for large current, is extended to the outer edge portion of the printed circuit board, a part of the housing is in thermal contact with the outer edge portion of the printed circuit board, and the housing is made of a metal first The printed circuit board is fastened to both cases in a state of being sandwiched between the first case and the second case. Yes.
[Selection] Figure 2

Description

 The present invention relates to an electronic control device for flowing a large current.

 A typical electronic control device includes a four-layer board having a thickness of about 35 μm and a rated current value of about 5 A as a multilayer board for component mounting, for example, an inner layer (a ground layer and a power supply layer). As a technique for improving the heat dissipation efficiency of such an electronic control device, an inner layer side heat transfer conductor for transmitting heat of the heat generating electronic component is provided on the inner layer of the multilayer substrate, and is formed at a position in contact with the cover on the surface of the multilayer substrate. By connecting the inner layer side heat transfer conductor to the ground conductor through a via, heat generated from the heat generating electronic component is transferred to the air through a path of inner layer side heat transfer conductor → ground conductor → cover. A technique for dissipating heat is known (see Patent Document 1 below).

JP 2008-130684 A

  As described above, conventionally, heat generated from heat generating electronic components in an electronic control device that does not require a large current is dissipated from a casing such as a metal cover through the inner layer of the multilayer substrate having a thickness of about 35 μm. However, in an electronic control device for flowing a large current of, for example, 40 A, the heat generation amount of the inner layer itself becomes extremely large (if the resistance value of the inner layer is the same, the heat generation amount of the inner layer increases in proportion to the square of the current). Therefore, sufficient heat dissipation effect cannot be obtained, and further improvement of heat dissipation efficiency is necessary.

   The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an electronic control device capable of improving the heat dissipation efficiency of the electronic control device for flowing a large current.

 In order to achieve the above object, according to the present invention, as a first solving means related to an electronic control device, a printed circuit board having an inner layer pattern formed on an inner layer and connected to a heat-generating component, and a housing for accommodating the printed circuit board The inner layer pattern is a large current inner layer pattern, and extends to the outer edge portion of the printed circuit board.

  In the present invention, as a second solving means relating to the electronic control device, in the first solving means, a part of the casing and the outer edge portion of the printed circuit board are in thermal contact. Features.

  According to the present invention, as a third solving means relating to the electronic control device, in the first or second solving means, the casing includes a first casing made of metal and a second casing. The printed circuit board is configured to be fastened to both housings while being sandwiched between the first housing and the second housing.

In the present invention, by extending an inner layer pattern for large current formed on the inner layer of the printed circuit board and connected to the heat generating component to the outer edge portion of the printed circuit board, the heat generated from the heat generating component is increased to the inner layer for large current. Because it can be transferred to the outer edge of the printed circuit board through the pattern to dissipate heat, and by using a large current inner layer pattern, the resistance value of the inner layer pattern is reduced compared to a general inner layer pattern. Even when a large current flows through the inner layer pattern, the amount of heat generated by the inner layer pattern itself can be suppressed.
In other words, according to the present invention, in addition to the basic heat dissipation from the housing that houses the printed circuit board (heat radiation from the inside of the housing), the heat radiation from the outer edge of the printed circuit board is also performed in an auxiliary manner. In addition, since the amount of heat generated by the inner layer pattern itself can be suppressed, it is possible to improve the heat dissipation efficiency of the electronic control device for flowing a large current.

It is an exploded perspective view of electronic control unit 1 concerning this embodiment. 3 is a view showing a cross-sectional structure of an outer edge portion of the printed circuit board 2. FIG.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.
FIG. 1 is an exploded perspective view of an electronic control device 1 using a large current according to the present embodiment. The electronic control device 1 is a control device that uses a large current and is, for example, an ECU (Electronic Control Unit) that is mounted on a vehicle and performs automatic opening / closing control of a vehicle door, and contains a printed circuit board 2 and the printed circuit board 2. And a metal case 3 (housing).

 The printed circuit board 2 is a rectangular multi-layer circuit board on which electronic components (not shown) necessary for automatic opening / closing control of the vehicle door and a connector 2a for connecting to an external device are mounted. This multilayer substrate is, for example, a four-layer substrate, a surface layer pattern (first layer and fourth layer) having a thickness of 35 μm, and an inner layer pattern (second layer and third layer) having a thickness of 70 μm for a large current. It is composed of The connector 2a is formed of, for example, a high thermal conductive resin such as PBT or PPS, and is fixed to the printed circuit board 2 with two connector fixing screws 4 penetrating from the back surface side to the front surface side of the printed circuit board 2. Has been. Further, four corner screw holes 2 b and a central screw hole 2 c for fixing the printed circuit board 2 to the case 3 are provided at the four corners and the central part of the printed circuit board 2.

 The case 3 is a metal case such as iron or aluminum that accommodates and protects the printed circuit board 2 therein, and includes a lower case 31 (first housing) and an upper case 32 (second housing). It can be divided into two parts. Four corner screw holes 31 a and a central screw hole 31 b for fixing the printed circuit board 2 are provided at the four corners and the center of the lower case 31. Also, four corner screw holes 32 a for fixing the printed circuit board 2 are provided at the four corners of the upper case 32.

The printed circuit board 2 has a component mounting surface facing upward, and passes through the central screw hole 2c of the printed circuit board 2 from the upper side to the lower side, and is screwed into the central screw hole 31b of the lower case 31. The lower case 31 is fixed by screws with screws 5. In the state where the printed circuit board 2 is fixed to the lower case 31, the upper case 32 penetrates the upper case 32 and the four corner screw holes 32a and 2b of the printed circuit board 2 from the upper side to the lower side, and the lower case 31 The lower case 31 is fixed by screws with case fixing screws 6 which are screwed into the four corner screw holes 31a.
In this way, the printed circuit board 2 is fastened to both cases 31 and 32 in a state of being sandwiched between the lower case 31 and the upper case 32.

  FIG. 2 is a diagram showing a cross-sectional structure of the outer edge portion of the printed circuit board 2 in a state where it is fastened together with the case 3 (31, 32). As shown in this figure, the printed circuit board 2 includes an insulating layer 2d formed of glass epoxy resin and the like, and an inner layer pattern 2e (ground pattern 2e1, power supply pattern) formed of a copper foil for high current and the like having a thickness of 70 μm. 2e2) are alternately stacked. Reference numeral 2f in the figure denotes a heat generating component that generates heat when a large current flows among electronic components mounted on the surface of the printed circuit board 2.

The ground pattern 2e1 for large current formed in the inner layer of the printed circuit board 2 is electrically connected to the heat generating component 2f through the via 2g and the surface layer pattern 2h, and extends to the outer edge of the printed circuit board 2. ing. The power supply pattern 2e ₂ for large current is also electrically connected to a heat generating component (not shown) and extends to the outer edge of the printed board 2. In order to prevent a short circuit with the ground pattern 2e1 for large current, the power pattern 2e2 for large current is patterned to avoid the via 2g.

 A part of the case 3 is in thermal contact with the outer edge of the printed circuit board 2 (particularly, the front surface and the back surface of the outer edge). Here, “thermal connection” refers to a physical contact or distance at which heat is transferred between the metal case 3 and the resin printed board 2. In the present embodiment, the case 3 and the printed board 2 are fastened together by the case fixing screw 6 and the case 3 is in contact with the printed board 2 with a large pressure. Good thermal conductivity can be secured.

In this way, by extending the inner layer pattern 2e for large current (particularly the ground pattern 2e1) formed on the inner layer of the printed circuit board 2 and connected to the heat generating component 2f to the outer edge of the printed circuit board 2, the heat generating component 2f The heat generated from the heat can be transferred through the path of the ground pattern 2e1 for large current → the outer edge of the printed circuit board 2 → the case 3 to dissipate heat in the air, and the inner layer pattern 2e for large current is used. Thus, since the resistance value of the inner layer pattern 2e is lower than that of a general inner layer pattern, the amount of heat generated by the inner layer pattern 2e itself can be suppressed even if a large current flows through the inner layer pattern 2e.
That is, according to the present embodiment, in addition to the basic heat dissipation from the case 3 that houses the printed circuit board 2 (heat dissipation from the heat filled in the case 3), heat dissipation from the outer edge of the printed circuit board 2 is also auxiliary. In addition, since the amount of heat generated by the inner layer pattern 2e itself can be suppressed, it is possible to improve the heat dissipation efficiency of the electronic control unit 1 for flowing a large current.

 Furthermore, the configuration of the present embodiment and the configuration described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2008-130684), that is, an inner layer side heat transfer conductor that transmits heat of the heat generating electronic component to the inner layer of the printed circuit board 2 are provided. If the configuration in which the inner layer side heat transfer conductor is connected via a via to the ground conductor formed at a position in contact with the upper case 32 on the surface of the printed circuit board 2, further improvement in heat dissipation efficiency can be realized. .

 The electronic control device 1 according to the embodiment of the present invention has been described above. However, the present invention is not limited to an ECU that is mounted on a vehicle and performs automatic opening / closing control of a vehicle door, and a printed board on which a connector is fixed with a screw. And an electronic control device including a housing that accommodates the printed circuit board.

  DESCRIPTION OF SYMBOLS 1 ... Electronic control device, 2 ... Printed circuit board, 2f ... Heat generating component, 2e ... Inner layer pattern for large currents, 3 ... Case (housing), 31 ... Lower case (first housing), 32 ... Upper case (Second housing)

Claims (3)

An electronic control device comprising: a printed circuit board having an inner layer pattern formed on an inner layer and connected to a heat generating component; and a housing for housing the printed circuit board,
The electronic control device according to claim 1, wherein the inner layer pattern is an inner layer pattern for a large current and extends to an outer edge portion of the printed circuit board.   The electronic control device according to claim 1, wherein a part of the casing and an outer edge portion of the printed circuit board are in thermal contact with each other. The case is composed of a first case made of metal and a second case,
3. The electronic device according to claim 1, wherein the printed circuit board is fastened to both housings while being sandwiched between the first housing and the second housing. 4. Control device.

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