JP5236178B2 - Electronic circuit equipment - Google Patents

Description

  The present invention relates to an electronic circuit device used in, for example, an automobile.

2. Description of the Related Art Conventionally, various proposals have been made for structures for dissipating heat generated by a heat generating electronic component in an electronic circuit device including the heat generating electronic component. For example, a heat-dissipating electrode is provided on a chip-type heat-generating component, and heat is transferred from the heat-dissipating electrode to the ground layer that is the inner layer of the printed circuit board through the heat-dissipating electrode pad and through hole on the printed circuit board. A configuration has been proposed in which the printed circuit board is taken out from the end face and connected to a heat sink to dissipate heat into the air (see Patent Document 1).
JP-A-6-169189

  In the above-described conventional electronic circuit device, since the heat sink is provided outside the printed circuit board, there may be a problem that the number of parts increases, the number of assembling steps increases, or the housing for housing the printed circuit board increases in size. There is sex.

  In order to prevent an increase in the size of the electronic circuit device, a configuration in which heat generated by the heat generating electronic component is transferred to the housing that houses the printed circuit board and radiated from the surface of the housing to the air can be considered. Since the casing is generally made of a metal material, for example, a so-called good heat conductor such as aluminum, it can effectively dissipate heat generated by the heat generating electronic component.

  By the way, the metal casing is normally set to the ground potential. In the case of the above-described conventional electronic circuit device, the heat radiation electrode of the heat generating electronic component is at the ground potential. However, depending on the type of heat-generating electronic component, there are many cases where the heat radiation electrode is not a ground potential but a positive potential. In the configuration of the above-described conventional electronic circuit device, the generated heat cannot be transferred to the casing for the heat generating electronic component whose heat dissipation electrode has a positive potential. In addition, the above-described conventional electronic circuit device has no description regarding coping means in such a case. If the heat dissipation electrode with a positive potential is tightly fixed to a heat sink made of metal or the like, the heat sink itself will also have a positive potential, thus protecting the electronic circuit device from contact with other electronic elements and wiring. There is a possibility that the electronic circuit device will be enlarged due to the mounting of the means.

  The present invention has been made in view of the above problems, and provides an electronic circuit device capable of transferring heat generated by a heat generating electronic component having a heat dissipation electrode having a positive potential to the housing to dissipate it into the air. For the purpose.

  In order to achieve the above object, the present invention employs the following technical means.

According to a first aspect of the present invention, there is provided an electronic circuit device comprising: a heat generating electronic element having a heat dissipation electrode; a multilayer substrate having the heat generating electronic element mounted on the surface thereof; and a housing for housing and fixing the multilayer substrate. An electronic circuit device comprising: a surface heat transfer conductor provided on a surface of the multilayer substrate to which a heat dissipation electrode is soldered; and a surface heat transfer conductor via an insulating member of the multilayer substrate in the thickness direction of the multilayer substrate. Provided on at least one of the inner layer side heat transfer conductor formed on the inner layer of the multilayer substrate and the front and rear surfaces of the multilayer substrate so as to overlap , and the potential is the ground potential, and can be conducted to the casing pressed by fastening A grounding conductor that is in contact , the heat dissipation electrode is at a positive potential, the inner layer-side heat transfer conductor is at a ground potential, the inner layer-side heat transfer conductor is connected to the housing so as to be able to conduct heat, and the thickness of the multilayer substrate Surface in direction It includes the surface heat transfer conductor so as to face across the heat conductor and the entire surface, the inner side heat transfer conductor, thermally conductively connected to the ground conductor through the conducting means, conducting means, of the ground conductor is characterized by multiple vias der Rukoto connecting in the pressed the region and the inner side heat transfer conductor in contact with the housing.

In the above-described configuration, the surface heat transfer conductor and the inner layer side heat transfer conductor are disposed to face each other via an insulating member. The heat generated by the heat generating electronic element is transmitted from the heat radiation electrode to the inner layer side heat transfer conductor through the surface heat transfer conductor and the insulating member. Then, heat is transferred from the inner layer side heat transfer conductor to the housing, and is radiated from the surface of the housing to the air. Here, the surface heat transfer conductor and the inner layer side heat transfer conductor are arranged via an insulating member, and both are not electrically connected. Therefore, the heat generated by the heat radiation electrode having a positive potential can be transmitted to the casing through the inner layer side heat transfer conductor having the ground potential without causing an electrical short circuit. Thus, it is possible to provide a heat radiating electrode is + potential at a heat-generating electronic component of the generated heat to heat dissipation to Rukoto an electronic circuit apparatus capable into the air is conducted to the housing. In addition, since the heat generated from the heat generating electronic element in the entire area of the heat dissipation electrode of the heat generating electronic element follows the shortest distance, that is, the distance in the thickness direction of the multilayer substrate, it is conducted to the inner layer side heat transfer conductor. Heat can be conducted with high efficiency from the surface heat transfer conductor to the inner layer side heat transfer conductor.

Further, since the ground conductor originally has a function of conducting the ground wire of the multilayer board to the casing, the ground conductor and the casing are electrically conductive and can conduct heat at the same time. Therefore, the heat generated by the heat generating electronic element is transmitted from the inner layer side heat transfer conductor to the ground conductor through the conduction means and further to the casing. Accordingly, it is possible to provide an electronic circuit device capable of transferring heat generated by the heat-generating electronic component whose heat dissipation electrode has a positive potential to the housing and dissipating the heat into the air.

The via is the most commonly used means for electrically conducting conductors of different layers in the multilayer substrate. The material of the via is a good electrical conductor, and is formed from, for example, a metal plating such as copper or a paste containing copper or silver. For this reason, the via can also function as a good thermal conductor. Therefore, the heat generated by the heat generating electronic element can be conducted from the inner layer side heat transfer conductor to the ground conductor by easy means.

The electronic circuit device according to claim 2 of the present invention is characterized in that the inner layer side heat transfer conductor is an inner layer conductor arranged on the most surface side among the inner layer conductors provided in the multilayer substrate.

  According to the above-described configuration, the distance from the surface heat transfer conductor to the inner layer side heat transfer conductor connected to the housing so as to be able to conduct heat can be minimized. That is, the surface heat transfer conductor and the inner layer side heat transfer conductor connected to the housing so as to be able to conduct heat are opposed to each other with only one insulating member therebetween. Thereby, heat can be conducted from the surface heat transfer conductor to the inner layer side heat transfer conductor with high efficiency.

  Hereinafter, an example in which an electronic circuit device according to the present invention is applied to an electronic circuit device 1 installed in a combination meter (not shown) of an automobile will be described with reference to the drawings.

  The combination meter 100 is provided in front of the driver's seat in the passenger compartment of an automobile, and displays various information related to the automobile, for example, traveling speed and the like by a pointer instrument, a warning light, and the like. The electronic circuit device 1 serves as an electric circuit that controls the overall operation of the combination meter 1. The electronic circuit device 1 is housed and fixed in a casing (not shown) of the combination meter 1. The configuration of the electronic circuit device 1 will be described below.

  The electronic circuit device 1 is configured by holding and fixing a multilayer substrate 3 on which various electronic elements and the like are mounted inside a casing 5 and a cover 6 which are casings.

  The multilayer substrate 3 forms the electronic circuit itself in the electronic circuit device 1. The multilayer substrate 3 is manufactured by a general build-up wiring plate forming method. For example, a sheet of glass epoxy resin as an insulating member and a copper foil as an electric conductor are alternately stacked and pressed. In the multilayer substrate 3 of the electronic circuit device 1 according to the embodiment of the present invention, a glass epoxy resin is used as the base material 30 that is an insulating member, and the electrical conductor is formed from a copper foil, as shown in FIG. The multilayer substrate 3 is provided with a total of four layers, one on each of the front and back surfaces of the multilayer substrate 3 and two layers inside the insulating member 35. That is, the surface conductor layer 31 is formed on the front surface 30A of the multilayer substrate 3, the surface conductor layer 34 is formed on the back surface 30B, and the inner layer conductor layer 32 and the inner layer conductor layer 33 are formed inside the base material 30 from the surface 30A side.

  A diode 2 that is a heat generating electronic element is mounted on the surface 30 </ b> A of the multilayer substrate 3. The diode 2 is used in, for example, a power control circuit (not shown) in the electronic circuit device 1. Therefore, the value of current flowing through the diode 2, that is, the value of current flowing through the semiconductor constituting the diode 2, is much larger than that of a transistor used in a logic circuit, a high-frequency circuit, etc., and therefore generates heat. In order to operate the diode 2 normally, it is necessary to dissipate the heat generated by the diode 2 to the outside and maintain the temperature of the diode 2 at an appropriate temperature, for example, below the junction temperature of the semiconductor. As shown in FIG. 2, the diode 2 includes three electrodes for electrical connection to the outside. That is, one heat radiation electrode 21 and two functional electrodes 22 and 23 are provided. The heat dissipating electrode 21 functions to electrically connect the diode 2 to the outside, and also transfers the heat generated by the diode 2 to the outside, thereby maintaining the temperature of the diode 2 appropriately. The heat radiation electrode 21 is formed to have a larger area as shown in FIG. 2 than the other two functional electrodes 22 and 23 in order to increase the amount of heat transferred. The potential of the heat radiation electrode 21 of the diode 2 is not a ground potential, that is, 0 volts, but a positive potential, for example, 12 volts.

  On the surface 30 of the multilayer substrate 3, surface heat transfer conductors 31A to which the heat radiation electrodes 21 of the diode 2 are connected and surface function conductors 31B and 31C to which the function electrodes 22 and 23 of the diode 2 are connected are formed. The surface heat transfer conductor 31 </ b> A is formed in substantially the same shape as the heat radiation electrode 21 of the diode 2. The surface functional conductors 31 </ b> B and 31 </ b> C are arranged at positions and shapes corresponding to the functional electrodes 22 and 23 of the diode 2 at the diode 2 side ends. As shown in FIG. 2, a ground conductor 31 </ b> D is formed on the surface 30 of the multilayer substrate 3. The potential of the ground conductor 31D is the ground potential, that is, 0 volts. When the multilayer substrate 3 is held and fixed inside the casing 5 and the cover 6 which are the casings, the ground potential 31D is in direct contact with the casing 6 and the cover 6 in the case of the electronic circuit device 1 according to the embodiment of the present invention. Thereby, in the electronic circuit device 1, the casing 5 and the cover 6 that are the casings are also at the ground potential. As shown in FIG. 2, the diode 2 is mounted close to the ground electrode 31D on the surface 30 of the multilayer substrate 3, and therefore the surface heat transfer conductor 31A is also close to the installation electrode 31D.

  The casing 5 and the cover 6 that are casings are made of metal, such as aluminum. When the bolt 7 is fastened with the multilayer substrate 3 sandwiched between the casing 5 and the cover 6, the multilayer substrate 3 is held and fixed inside the casing, that is, the casing 5 and the cover 6. At this time, as shown in FIG. 3, the cover 6 is in press contact with the ground conductor 31 </ b> D of the multilayer substrate 3, and the multilayer substrate 3 is grounded to the casing 5 and the cover 6.

  Next, the heat radiating structure of the diode 2, that is, the heat radiating structure from the diode 2 to the cover 6, which is a feature of the electronic circuit device 1 according to the embodiment of the present invention, and its operation, that is, heat transfer will be described.

  Of the inner layer conductor layers 32 and 33 of the multilayer substrate 3, the inner layer conductor layer 32 that is closest to the surface 30A overlaps the surface-side heat transfer conductor 31A in the thickness direction of the multilayer substrate 3 (vertical direction in FIG. 3). Thus, the inner layer side heat transfer conductor 32A is formed. Specifically, the inner layer side heat transfer conductor 32A overlaps the surface side heat transfer conductor 31A in the thickness direction of the multilayer substrate 3 (vertical direction in FIG. 3), and as shown in FIG. In other words, the contour line of the surface side heat transfer conductor 31A is formed so as to be inside the contour line of the inner layer side heat transfer conductor 32A. The inner layer side heat transfer conductor 32A and the ground conductor 31D are connected to each other through a via 4 serving as a conduction means. Therefore, the potential of the inner layer side heat transfer conductor 32A is the same as the ground potential of the ground conductor 31D. Here, the via 4 is generally used as means for electrically connecting different conductor layers in a normal multilayer substrate. As the material of the via 4, for example, copper paste, silver paste, copper plating, or the like is used. Copper and silver are good conductors of heat as well as good conductors of electricity. Therefore, the inner layer side heat transfer conductor 32 </ b> A and the ground conductor 31 </ b> D are connected via the via 4 so as to be able to conduct heat. In the electronic circuit device 1 according to the embodiment of the present invention, eight vias 4 are provided as shown in FIG. 1, but the number of vias 4 is not limited to eight. It is increased or decreased according to the amount of heat transfer between the heat transfer conductor 32A and the ground conductor 31D.

  Next, heat transfer in the above heat dissipation structure will be described.

  The diode 2 is connected and fixed to the surface side heat transfer conductor 31A and the functional electrodes 22 and 23 to the functional conductors 31B and 31C via solder layers (not shown) on the surface 30A of the multilayer substrate 3, respectively. Has been. The heat radiation electrode 21 is in close contact with the surface-side heat transfer conductor 31A through a solder layer (not shown) over the entire surface. When the diode 2 generates heat and its temperature rises as the electronic circuit device 1 operates, most of the heat generated by the diode 2 is transferred from the heat radiation electrode 21 having a positive potential to the surface side heat transfer conductor 31A by heat conduction. Communicated. As a result, the temperature of the surface side heat transfer conductor 31A rises, and heat is transferred from the surface side heat transfer conductor 31A through the base material 30 to the inner layer side heat transfer conductor 32A by heat conduction. Here, the surface side heat transfer conductor 31 </ b> A has the same + potential as the heat radiation electrode 21 of the diode 2. On the other hand, the inner layer side heat transfer conductor 32A is electrically connected to the ground conductor 31D and has a ground potential. Since the surface side heat transfer conductor 31A faces the inner layer side heat transfer conductor 32A via the base material 30 which is an insulating member, both are arranged so as to be able to conduct heat while maintaining an electrically insulated state. The heat transferred to the inner layer side heat transfer conductor 32A is further transferred to the cover 6 by heat conduction through the via 4 and the ground conductor 31D. And it is dissipated in the air by heat transfer from the surface of the cover 6.

  By the way, the thermal conductivity of the epoxy resin as the base material 30 is about 0.2 [W / mK], which is much higher than the thermal conductivity of about 390 [W / mK] of copper forming each conductor. Small. That is, the degree of heat transfer is small. However, in the multilayer substrate 3, the thickness of the base material 30 layer between the surface side heat transfer conductor 31A and the inner layer side heat transfer conductor 32A is very thin, for example, 0.2 mm. A predetermined amount of heat can be transmitted to the side heat transfer conductor 32A. Thus, although the epoxy resin base material 30 is in the middle of the heat transfer path from the heat radiation electrode 21 of the diode 2 to the cover 6, the heat generated by the diode 2 is transmitted to the cover 6, and the air from the surface of the cover 6 Can be dissipated inside. Therefore, the temperature of the diode 2 can be maintained in an appropriate temperature range in which normal operation is possible.

  According to the configuration of the electric circuit device 1 according to the embodiment of the present invention described above, the heat generated by the diode 2 mounted on the surface 30A of the multilayer substrate 3 and the heat radiation electrode 21 having a positive potential is generated. Is transmitted to the ground conductor 31D on the surface 30A of the multilayer board 3 through the inner layer side heat transfer conductor 32A and the via 4, and further transmitted from the ground conductor 31D to the cover 6 which is a casing and diffused into the air from there. Can be made. As a result, the heat generation electronic component is fixed to a heat dissipation means such as a heat sink, and the heat generated from the heat generation electronic component with the heat dissipation electrode having a positive potential can be effectively incorporated into the enclosure by adopting easy means without taking short circuit prevention means. An electronic circuit device capable of transferring heat and radiating heat into the air can be realized.

  Next, a modification of the electronic circuit device 1 according to one embodiment of the present invention will be described with reference to FIG.

  In the modification of the electronic circuit device 1 according to the embodiment of the present invention, the multilayer substrate 3 includes the ground electrode 34A on the back surface 30B. The ground electrode 34 </ b> A is in close contact with the casing 5 when the multilayer substrate 3 is fixed to the casing 5, and is electrically connected to the casing 5 in an electrically and thermally conductive manner.

  Of the inner layer conductor layers 32, 33 of the multilayer substrate 3, the inner layer conductor layer 33, which is the layer closest to the rear surface 30B, and the back surface are provided with the inner layer side heat transfer conductor 32A in the thickness direction of the multilayer substrate 3 (vertical direction in FIG. 3). The inner layer side heat transfer conductor 33A is formed so as to overlap. As shown in FIG. 4, the inner layer side heat transfer conductor 33 </ b> A and the inner layer side heat transfer conductor 32 </ b> A are connected via the via 4 so as to be electrically and thermally conductive. Further, as shown in FIG. 4, the inner layer side heat transfer conductor 33 </ b> A and the ground conductor 34 </ b> A are connected via the via 4 so as to be electrically and thermally conductive. Therefore, the inner layer side heat transfer conductor 32A is connected to the ground conductors 31D and 34A on both surfaces of the multilayer board 3 so as to be electrically and thermally conductive. In this case, a part of the heat generated by the diode 2 transmitted to the inner layer side heat transfer conductor 32A is transmitted to the cover 6 through the ground conductor 31D, and the remaining part is transmitted to the casing 5 through the ground conductor 34A. As a result, the heat dissipation path generated by the diode 2 can be added to reliably dissipate the heat generated by the diode 2 into the air.

  In the electronic circuit device 1 according to the embodiment of the present invention described above and the modification thereof, the diode 2 is described as an example of the heat generating electronic element. However, it is necessary to limit the heat generating electronic element to the diode 2. However, the present invention may be applied to other types of heat generating electronic elements. For example, a transistor, a regulator, or the like may be used.

  Further, in the speedometer S according to the embodiment of the present invention described above, the halftone dot printing layer applied to the gradation portion 3 is formed from the round dots 33, but the shape of the dots need not be limited to a circle. Other shapes may be used.

  Further, in the electronic circuit device 1 according to the embodiment of the present invention described above and the modification thereof, the inner conductor layer of the multilayer substrate 3 is two layers, but it is not necessary to limit to two layers. Three or more layers may be used.

  In the embodiment described above, the application of the electronic circuit device according to the present invention is the electronic circuit device 1 mounted in a combination meter of an automobile. However, the application of the electronic circuit device is used other than for automobiles, for example, You may apply to the electronic circuit apparatus with which various consumer equipment is provided.

It is a fragmentary sectional view of the electronic circuit device 1 by one Embodiment of this invention, and is the II sectional view taken on the line in FIG. It is II arrow directional view in FIG. It is the III section enlarged view in FIG. It is a fragmentary sectional view of the modification of the electronic circuit device 1 by one Embodiment of this invention, and is equivalent to FIG.

Explanation of symbols

1 Electronic circuit device 2 Diode (heat generating electronic element)
21 Electrodes for heat radiation 22, 23 Functional electrodes 3 Multilayer substrate 30 Base material (insulating member)
30A surface 30B back surface 31 surface conductor layer 31A surface heat transfer conductor 31B, 31C functional conductor 31D ground conductor 32 inner layer conductor layer 32A inner layer side heat transfer conductor 33 inner layer conductor layer 33A inner layer side heat transfer conductor 34 surface conductor layer 34A ground conductor 4 via (Copper thread)
5 Casing
6 Cover (Housing)
7 volts

Claims (2)

A heat generating electronic element having a heat dissipating electrode;
A multilayer board on which the heat generating electronic elements are mounted;
An electronic circuit device comprising a housing in which the multilayer substrate is stored and fixed,
A surface heat transfer conductor provided on the surface of the multilayer substrate and soldered to the heat dissipation electrode;
An inner layer-side heat transfer conductor formed in the inner layer of the multilayer substrate so as to overlap the surface heat transfer conductor via an insulating member of the multilayer substrate in the thickness direction of the multilayer substrate ;
A ground conductor provided on at least one of the front surface and the back surface of the multilayer substrate, the potential of which is a ground potential and in contact with the housing pressed by fastening ;
The heat dissipating electrode is a positive potential, and the inner layer side heat transfer conductor is a ground potential;
The inner layer side heat transfer conductor is connected to the housing so as to be capable of conducting heat, and includes the surface heat transfer conductor so as to face the entire surface of the surface heat transfer conductor in the thickness direction of the multilayer substrate ,
The inner layer side heat transfer conductor is connected to the ground conductor through a conduction means so as to be capable of conducting heat,
The conducting means, the electronic circuit device according to claim plurality of vias der Rukoto connecting the pressed area in contact with the housing was an inner layer-side heat transfer conductor of the ground conductor. Electronic circuit device according to claim 1 wherein the inner layer-side heat transfer conductor, wherein the inner conductor der Rukoto most said is disposed on the surface side of the inner conductor provided in the multilayer substrate.

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