JP2012079834A - Heat radiation structure of heating component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat radiation structure of heating components which focuses attention on characteristics of a mounting substrate of a heat emitting component, particularly having a switching function, and attains proper heat radiation effect through a simple structure.SOLUTION: This invention focuses attention on a structure of a multilayer substrate 6, in which an H bridge circuit 5 using FETs 1 to 4 that are heating components having multiple switching functions, i.e., a laminate structure having an insulation layer 66 or the like to prevent noise from leaking to the exterior. At least multiple portions of the insulation layer 66 which functions for each heating component are exposed on a surface layer to be used as the insulation sheet, and a heat sink 7 serving as a heat radiation member which functions for each heating component is directly attached thereto.

Description

  The present invention relates to a heat-dissipating structure for a heat-generating component that can easily and appropriately dissipate heat from the heat-generating component in an H-bridge circuit or the like.

  Conventionally, when a heat generating component is mounted on a printed wiring board, a heat radiating member (fin) is provided separately from the printed wiring board, and a heat radiating portion of the heat generating component is generally attached to the heat radiating member. However, the heat generating component needs to be attached to the fin via an insulator, and it is necessary to perform a lead forming process with the printed wiring board.

  Therefore, considering the mounting cost, it is effective to surface mount the heat generating component on the printed wiring board. In this case, it is necessary to solve how to dissipate the heat of the heat generating portion by surface mounting.

  In order to deal with such a problem, for example, as shown in Patent Document 1, a method of mounting fins on a wiring pattern, or in addition to that, the pattern width is increased (or a dedicated heat dissipation pattern is provided) to pattern the heat dissipation portion. A method of attaching directly to the heat sink, and a method of directly dissipating heat by mounting fins on the heat-generating component are considered as effective means.

JP 2000-332171 A

  However, in the method of the above-mentioned Patent Document 1, fins are separately mounted on the printed wiring board, and an insulating sheet or the like is required between them, which takes man-hours and costs, reduces the space factor of the mounting surface, The entire mounting board becomes bulky, leading to an increase in the size of components. On the other hand, if the pattern width is increased (or if a dedicated heat dissipation pattern is provided), there is a problem that the substrate becomes larger, and it is desirable to avoid providing a bus bar or the like separately.

  The present invention has been made paying attention to such problems, and particularly paying attention to the characteristics of the mounting substrate of the heat-generating component having a switching function, so that an appropriate heat dissipation effect can be obtained through a simple structure. It aims at providing the heat dissipation structure of a heat-emitting component.

  In order to achieve this object, the present invention takes the following measures.

  That is, the heat dissipation structure for a heat generating component according to the present invention is applied to a multilayer substrate including a wiring board conductor on which a heat generating component having a switching function is mounted and an insulating layer bonded to the wiring board conductor in a polymerized state. According to another aspect of the present invention, the insulating layer is exposed to at least a surface layer of the multilayer substrate, and a heat radiating member is directly attached to the exposed portion.

  In the first place, those having a switching function such as an H-bridge have large dv / dt and di / dt and are likely to generate electrical noise. A laminated structure with a conductor is usually adopted. This type of component generates a large amount of heat due to switching loss.

  Therefore, in the present invention, the insulating layer is exposed on the surface of the substrate, and this is used as an insulating sheet, and the heat radiating member is directly attached thereto. In this way, the heat radiating member can be attached without using a separate insulating sheet, bus bar, etc., and the insulating layer is bonded to the wiring pattern, and the heat pumping effect is exerted on the entire wiring pattern. Further, since the pattern width and the number of patterns on the mounting surface are not changed, it is possible to effectively avoid adverse effects on the mounting.

  Even if a plurality of heat-generating components are mounted on the wiring pattern, the common heat-dissipating member can be connected to the plurality of insulating layers by making the heat-generating components electrically disconnected from each other by the common insulating layer. Can be attached directly to the place.

  Since the present invention has the configuration described above, the following effects are produced.

  That is, according to the heat dissipation structure of the present invention, it is possible to obtain a heat dissipation effect without noise propagation without using a special wiring component such as a bus bar in a switching circuit configuration such as an H bridge having a heat generating component. . In addition, since the heat dissipating member is directly attached to the substrate on which the heat generating components are mounted, lead forming processing for attaching the heat generating components to the separate heat dissipating components is unnecessary, reducing the mounting man-hours and mounting freedom. The range of component selection can be expanded from the degree. Furthermore, since heat is radiated simply by placing a heat radiating member on the substrate, it is not always necessary to prepare a special wiring board or a casing to be a heat sink. Furthermore, since the heat radiating component is directly attached to the exposed portion of the insulating layer, it is possible to reduce the cost without the need for an insulating sheet.

The block diagram of the H bridge circuit provided with the heat-emitting component to which the thermal radiation structure which concerns on one Embodiment of this invention is applied. The typical sectional view of the substrate which attached the heat sink concerning the heat dissipation structure. FIG. 3 is a partial plan view of FIG. 2. Sectional drawing corresponding to FIG. 2 which shows the modification of this invention. The typical perspective view which shows that the same heat sink serves also as the attachment components to a vehicle. Sectional drawing corresponding to FIG. 2 which shows the other modification of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  In this embodiment, as shown in FIG. 1, the heat-radiating structure of the present invention is applied to a motor control device in which an H-bridge circuit 5 is configured using four FETs 1 to 4 as the heat-generating parts. It is applied.

  As is well known, the H bridge circuit 5 has a structure in which FETs 1 to 4 are arranged in an H shape at both ends of a load W such as a motor, in other words, each parallel circuit connected to the power source E. A pair of FETs 1, 2, FETs 3, 4 are arranged in series on the branch paths L 1, L 2, respectively, and between the source S of the high-side FETs 1, 3 and the drain D of the low-side FETs 2, 4 in each branch path L 1, L 2. In this configuration, the load W is connected to the gate G, and the current flowing through the gate G is controlled to perform the switching operation for the load W.

  As a specific example of forming such an H-bridge circuit 5 on a laminated substrate, the potentials of the drains D of the high-side FETs 1 and 3 and the sources S of the low-side FETs 2 and 4 are stable, as shown in FIG. In this way, a wiring conductor 61 for forming a wiring pattern is provided on the surface layer of the laminated substrate 6 and necessary portions are connected to this, and the source S of the high-side FETs 1 and 3 and the drain D of the low-side FETs 2 and 4 are, for example, 0V to 12V Since the potential and current fluctuate drastically, for example, by performing a switching operation between them, it is preferable to provide wiring conductors 62 and 63 for forming a wiring pattern on the inner layer of the multilayer substrate 6 and connect a required portion thereto. The wiring conductors 61, 62, 63 are bonded to each other with the insulating layers 64, 65 interposed therebetween, and in order to prevent noises due to dv / dt, di / dt, A structure is also adopted in which an insulating layer 66 is bonded to the back surface, which is the surface layer, to block noise. The FETs 1 to 4 are attached to the surface layer on the front surface side, and necessary portions are electrically connected to the wiring conductor 61 by surface mounting, and other necessary portions are connected to the inner wiring conductors 62 and 63 through through holes or the like. Electrically connected.

  In the present embodiment, heat from the FETs 1 to 4 and other heat-generating components is dissipated mainly from a portion where heat generation is large, including a connection portion between the source S of the high-side FETs 1 and 3 and the drain D of the low-side FETs 2 and 4. In order to achieve this, a heat radiating plate 7 made of a material such as a metal having high thermal conductivity or ceramic, which is a heat radiating member, is directly attached to the insulating layer 66 exposed on the back side of the multilayer substrate 6 and is shown by arrows in FIG. Thus, the heat of the wiring conductor is radiated through the insulating layer. Of course, when the insulating layer is not exposed on the surface layer on the back side and is covered with some wiring conductor 60 as shown in FIG. 3, the wiring conductor 60 is partially cut away, etc. A region where the insulating layer 66 is directly exposed to a part (wiring prohibited portion) may be secured, and the heat sink 7 may be directly attached to the exposed portion.

  In this embodiment, four FETs 1 to 4 of FIG. 1 and FIG. 2 that are heat generating components are mounted on the surface side of the multilayer substrate 6, but the insulating layers 64, 65, and 66 are common to the FETs 1 to 4. Since it exists over almost the entire area in the plane direction of the multilayer substrate 6 to serve as a noise blocking layer, each of the FETs 1 to 1 can be set at any position in the plane direction by setting the exposed portion to which the heat radiating member 7 is attached. 4 leads to heat dissipation effect. If the heat radiating plate 7 is a flat plate, the whole may be adhered evenly (solid pasting). However, as shown in FIG. 4, thick rising portions 72 are provided at a plurality of positions of the flat plate portion 71 constituting the heat radiating plate 7. The raised portion 72 may be abutted against a corresponding portion of the insulating layer 66 constituting the back surface of the multilayer substrate 6, and the multilayer substrate 6 may be fixed to the heat radiating plate 7 with screws 8.

  In any case, the heat generated in the wiring board conductors 62 and 63 provided in the inner layer with large heat generation is pumped out to the heat radiating plate 7 through the resin of the insulating layers 65 and 66 by the above configuration. The heat of the entire wiring pattern constituted by the conductors 62 and 63 is radiated.

  The surface layer side wiring board conductor 61 can radiate heat into the air itself, but the drain D of the high-side FETs 1 and 3 and the source S of the low-side FETs 2 and 4 each have a stable potential, and the through hole 8a of the screw 8 is used for wiring. If the conductors 62 and 63 are electrically insulated, a so-called solid pattern that increases the pattern width of the wiring pattern composed of the wiring conductors 64 arranged on the surface layer on the surface side is formed through the screws 8. Alternatively, a structure in which the heat sink is thermally connected to the heat sink 7 on the back surface side may be employed.

  In this embodiment, as shown in FIG. 5, after the laminated substrate 6 is attached to the heat radiating plate 7, the laminated substrate 6 is sealed together with heat-generating components by a sheet metal lid 9, and the heat radiating plate 7 is directly attached to the car. A screwing portion that is used as an attachment part and uses the screw insertion hole 6x provided in the multilayer substrate 6 or the screw hole 7x provided in the heat sink 7 also serves to prevent the multilayer substrate 6 from falling off due to vibration. Since the heat radiating plate 7 is thermally connected to a car chassis or the like, it is effective in pumping heat to the heat sink. Of course, you may attach the laminated substrate 6 and the heat sink 7 by uneven | corrugated engagement etc. FIG. Furthermore, even if the heat radiating plate 7 is attached in a state of being thermally separated from a car chassis or the like, a structure in which the heat radiating effect is completed by heat radiation or conduction from the heat radiating surface of the heat radiating plate 7 can be adopted. Even when the chassis is a common ground with other batteries or the like, the switching noise from the FETs 1 to 4 is cut through the insulating layer 66 and the like, so that adverse effects on the battery and the like can be reduced or eliminated. is there.

  As described above, in the present embodiment, the structure of the multilayer substrate 6 in which the H bridge circuit 5 using the FETs 1 to 4 that are the heat generating components having the switching function is incorporated, that is, the insulating layer 66 for preventing noise from coming out. In particular, the insulating layer 66 is exposed on the surface layer, and this is used as an insulating sheet, and the heat radiating plate 7 as a heat radiating member is directly attached thereto. The insulating layer 66 can be attached to the wiring conductors 62 and 63 forming the wiring pattern and the heat pumping effect can be expected over the entire wiring pattern. In addition, since it is not necessary to change the pattern width and the number of patterns on the mounting surface or attach a new bus bar, the laminated substrate 6 is modified. Without went to enable heat dissipation of the heat generated from the heat generating components such as FET1～4, ensure a predetermined switching function, it is possible to maintain.

  In addition, the insulating layer 66 and the like are common to the four FETs 1 to 4 that are heat-generating components, and a plurality of or the entire insulating layer 66 is exposed to the surface layer, and the heat sink is common to the exposed portions. 7 can be directly attached, so the degree of freedom of mounting of the heat sink 7 is high, and it is possible to optimize the design in consideration of heat dissipation efficiency and the like.

  As mentioned above, although one Embodiment of this invention was described, the specific structure of each part is not limited only to embodiment mentioned above.

  For example, if there is a margin on the mounting surface, as shown in FIG. 6, the insulating layer 64 located near the surface side of the multilayer substrate 6 may be exposed on the surface side and the heat dissipation member 107 may be directly attached. As shown in the figure, the heat radiation member 7 may also be used on the back side to synergistically enhance the heat radiation effect on the multilayer substrate 6.

  In addition, the present invention basically eliminates the need to newly provide an insulating layer such as an insulating sheet that does not constitute a laminated substrate. However, such an insulating layer is separately attached to further enhance the heat dissipation effect. It does not prevent it.

  Further, silicon grease or the like may be applied between the wiring board and the heat dissipating component in order to increase the degree of adhesion.

  Furthermore, when a further heat radiation effect is required, the drain side wiring of the low-side FET is converted into a bus bar, the surface layer is insulated, and it is not hindered by attaching it to a heat radiating metal part to radiate heat.

  Other configurations can be variously modified without departing from the spirit of the present invention.

1-4 ... Heat generation parts (FET)
6 ... Laminated substrate 7, 107 ... Heat dissipation member (heat sink)
64, 65, 66 ... insulating layer

Claims (1)

The present invention is applied to a laminated board comprising a wiring board conductor on which a heat generating component having a switching function is mounted, and an insulating layer bonded to the wiring board conductor in a superposed state, and a plurality of wiring board conductors are provided on the wiring board conductor. When mounting heat-generating components, at least a plurality of insulating layers common to each heat-generating component are exposed on the surface layer of the multilayer substrate, and the corresponding portions of the common heat dissipation member are directly attached to the exposed portions. The heat dissipating structure of the heat generating component.

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