JP4851154B2 - Circuit board built-in housing - Google Patents

Description

  The present invention relates to a circuit board built-in housing in which a circuit board on which a power supply system component and / or a signal system component is mounted, and particularly to a technical field of a heat radiating means for radiating heat from the circuit board.

  2. Description of the Related Art In recent years, automobiles are equipped with a large number of electrical components, and power supply lines for supplying power to these electrical components and signal lines for transmitting signals are routed in the vehicle body. In addition, in order to connect such a power supply line and signal line to each electrical component, a junction box is mounted at a main portion in the vehicle body.

  The junction box consists of a circuit board on which a power circuit for distributing power and a signal circuit for distributing control signals are formed, a relay for processing control signals, a fuse for protecting power, and external electrical components. A connector for connection, an ECU, and the like are incorporated.

  Terminals from connectors are connected to the circuit board, and circuit components such as relays are also mounted. Therefore, it is necessary to appropriately dissipate heat from the circuit board so that the temperature of the circuit board does not rise due to heat released from the circuit components and the like. The heat applied to the circuit board is not uniform on the board, and a heat spot is generated at a position where a component having a large calorific value is mounted.

  Conventionally, as a heat dissipation means from a circuit board, there is one using a metal core substrate for the circuit board. This has a metal plate in the center and a structure in which the metal plate is sandwiched between resins, and has the effect of improving the heat conductivity of the circuit board and suppressing the temperature rise at the heat spot. Also known is a structure in which a central metal plate is exposed at the peripheral edge of the metal core substrate and heat is radiated directly from the metal plate to the outside.

As another means for radiating heat from a circuit board, for example, a structure having a radiating fin 104 as shown in FIG. 11 is disclosed (Patent Document 1). In the heat dissipation means shown in the figure, the entire surface of the circuit board 102 on which the electronic component 101 is mounted is provided in contact with the heat dissipation fins 104 via the heat dissipation sheet 103. The heat radiating fins 104 are exposed to the outside from a part of the housing 105, and thereby have a structure for radiating heat to the outside.
JP-A-9-18176

However, the conventional heat dissipation means has the following problems.
In the structure in which the central metal plate is exposed at the peripheral edge of the metal core substrate and heat is radiated directly from the metal plate to the outside, it is necessary to provide an exposed portion in addition to the portion that forms the circuit, so the circuit substrate must be enlarged. However, it was a major obstacle to the miniaturization of the junction box. Moreover, the process which exposes a metal plate was needed and became the factor which raises manufacturing cost.

  In addition, in the heat dissipation structure shown in FIG. 11, it is necessary to provide the heat dissipation fins 104 through the heat dissipation sheet 103 on the entire surface of the circuit board 102 in order to suppress the temperature rise at the heat spot. There was a problem of increased costs. Moreover, although it is necessary to project the heat radiating fins 104 to the outside from the surface of the housing 105, there is also a problem that the height of the entire housing is increased by the amount of the heat radiating fins 104 projected.

Further, the circuit board 102 and the heat dissipation sheet 103 are directly in contact with the surface on which the heat dissipation sheet 103 of the circuit board 102 is provided, or the heat generating electronic component 101 is placed on the heat dissipation sheet 103. It is necessary to dissipate heat by providing the electronic component 101 in direct contact with the heat dissipating sheet 103. Further, the heat dissipation structure of FIG. 11 does not consider any through-hole connection of terminals. When the terminals are connected through holes, there is a concern that the tip of the terminal and the radiating fin 104 are short-circuited.
For this reason, there is a problem that a great restriction is imposed on the arrangement of the electronic component 101 on the circuit board 102.

  Therefore, the present invention has been made to solve these problems, efficiently dissipating heat from the circuit board, reducing restrictions on the placement of components mounted on the circuit board, and facilitating downsizing. An object of the present invention is to provide a case with a built-in circuit board.

A first aspect of a circuit board built-in housing according to the present invention is a circuit board built-in housing in which a circuit board having a first surface and a second surface is built in a case, and the circuit board includes a metal core substrate. A heat conductive sheet fixed to the first surface of the metal core substrate, and a heat dissipating component fixed to the surface of the heat conductive sheet opposite to the fixed surface of the metal core substrate and from which a plurality of protrusions protrude. the Bei example, the heat-radiating element, via an opening provided in the case, installed in the state of being partially exposed to the outside of said case, said case portions for fixing the heat dissipating component, the heat sink A circuit board built-in housing having a labyrinth structure extending beyond at least one of the plurality of protrusions to a bottom portion between the protrusions .

In the second aspect, a through hole is formed in the metal core substrate, a mounting component is disposed on the second surface of the metal core substrate, a terminal of the mounting component is disposed in the through hole, and a tip thereof is provided. Inserted and fixed in a state of protruding from the first surface, the heat conductive sheet is made of an insulating material and formed with a thickness exceeding the tip length of the terminal protruding from the metal core substrate. A housing with a built-in circuit board,

According to a third aspect, on the surface of the metal core substrate on the side where the terminal protrudes, the connectors are surface-mounted in opposing state on both side edge areas, and the thermal conductive sheet is disposed between the connector mounting areas. A housing with a built-in circuit board, which is arranged in a central area.

  According to the present invention, it is possible to provide a circuit board built-in housing that efficiently dissipates heat from the circuit board, reduces restrictions on the placement of components mounted on the circuit board, and is easy to downsize.

  A configuration of a circuit board built-in housing according to a preferred embodiment of the present invention will be described in detail with reference to the drawings. Below, the junction box mounted in a motor vehicle is demonstrated to an example as a circuit board built-in housing | casing. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description.

  1-3 is a figure which shows the structure of the junction box which is a circuit board built-in housing | casing which concerns on 1st embodiment of this invention. 1 shows a side view of the junction box 1 as viewed from the side, FIG. 2 shows a top view as seen from above, and FIG. 3 shows a bottom view as seen from below. 1 to 3 show the internal structure of the junction box 1, and the upper case and the lower case forming the outer wall are omitted.

  FIG. 4 shows a cross-sectional view of the junction box 1 as seen in the AA cross section of FIG. FIG. 5 is a partially enlarged view of FIG. In FIG. 4, in addition to the internal structure of the junction box 1, an upper case 11 and a lower case 12 are also displayed.

  The junction box 1 includes a metal core board 2, a board connector 3, a fuse holder 4, and an ECU 5 on which power supply system parts and signal system parts are mounted, in an upper case 11 and a lower case 12. Moreover, the heat conductive sheet 6 and the heat sink 7 are provided as a heat radiating component.

In the junction box 1, a metal core substrate 2 is used as a circuit substrate. The metal core substrate 2 has a first surface 2a and a second surface 2b. On the first surface 2a, mounted components by surface mounting such as the board connector 3a and the semiconductor relay 10 are mounted. On the second surface 2b, mounted components such as a board connector 3b, a fuse holder 4 and an ECU 5 are connected by through-hole connection.
As described above, various components are mounted on the metal core substrate 2, and heat generated from each mounted component is transmitted to the metal core substrate 2.

  For example, as shown in FIG. 5, the metal core substrate 2 is obtained by sandwiching a plate-like core material 41 made of a metal having good thermal conductivity such as copper in a sandwich shape with two insulating coatings 42 and 42. The through hole 43 penetrating the first surface 2a and the second surface 2b is formed, the copper foil portion 44 is formed on the surface, and the circuit pattern 45 is appropriately formed on the insulating coatings 42, 42, These are further covered with an insulating solder resist 48, and the terminal 14 such as the fuse holder 4 is inserted into the through hole 43 and fixed with solder 47.

Since the metal core substrate 2 has the core material 41 made of metal at the center, the metal core substrate 2 is excellent in soaking characteristics.
As shown in FIG. 5, in the junction box 1, the heat conductive sheet 6 is stuck and fixed to a part of the first surface 2 a of the metal core substrate 2, and the metal core substrate 2 of the heat conductive sheet 6 is further fixed. A heat sink 7 is stuck and fixed in close contact with the surface opposite to the fixed surface.

  As shown in FIG. 2, on the first surface 2a of the metal core substrate 2, each mounted component (substrate connector 3a or semiconductor relay 10) is disposed in the opposing edge areas A1 and A2, and is a terminal for surface mounting. 15 is electrically connected to the circuit pattern on the substrate. The heat conductive sheet 6 is arranged in a straight line in the central area A3 between the edge area A1 and the edge area A2.

  The heat conductive sheet 6 is a highly heat conductive pressure sensitive adhesive sheet such as, for example, an FPCO TM sheet (manufactured by FP Corporation), and functions as a heat conductive material that efficiently transfers the heat of the metal core substrate 2 to the heat sink 7.

  The heat sink 7 is a highly heat conductive metal member such as aluminum in which a plurality of protrusions protrude from a plate-like base that contacts the heat conductive sheet 6.

  As shown in FIG. 5, in the junction box 1, the tip side of the board connector 3b of the metal core board 2 and the terminal 14 for connecting the through hole of the fuse holder 4 protrudes from the first surface 2a (hereinafter, this part). Is referred to as a protrusion 14a). If this protrusion 14a comes into contact with the heat sink 7, a short circuit occurs, which may cause an electrical failure.

  Therefore, in the junction box 1 of this embodiment, the insulating heat conductive sheet 6 having a thickness T larger than the protruding length L of the protruding portion 14a of the terminal 14 is used (that is, T> L), and the heat conductive sheet 6 is used. Is stuck to the first surface 2a of the metal core substrate 2 in a state where it is stabbed into the protruding portion 14a of the terminal 14, and is fixed to the metal core substrate 2.

For example, when the protruding length L of the protruding portion 14a of the terminal 14 is 3 mm, for example, the thickness of the heat conductive sheet 6 is set to about 5.5 mm.
Thereby, the space | interval of the terminal 14 and the heat sink 7 is ensured by thickness (TL) with the heat conductive sheet 6, and the short circuit by both contact is prevented. This also allows the heat sink 7 to be disposed in the area where the protruding portion 14a of the terminal 14 is formed, which is preferable from the viewpoint of reducing the size of the junction box 1.

  As described above, in the junction box 1 of the present invention, the metal core substrate 2 having excellent temperature uniformity characteristics is used as a circuit board, the heat generated on the metal core substrate 2 is equalized, and the first metal core substrate 2 The heat generated on the metal core substrate 2 can be efficiently released to the outside of the junction box 1 by dissipating heat through the heat conductive sheet 6 and the heat sink 7 adhered and fixed to the surface 2a.

  With such a configuration, even if the heat conductive sheet 6 and the heat sink 7 are connected to only a part of the metal core substrate 2, the heat sink 7 can collect heat via the metal plate of the metal core substrate 2. It becomes possible and the outstanding heat dissipation effect can be acquired.

  In particular, in recent years, a large number of relays such as the semiconductor relay 10 generating a large amount of heat have been used for higher functionality. However, as described above, heat is radiated from the metal core substrate 2 to the heat sink 7 via the heat conductive sheet 6. By adopting such a configuration, it is possible to efficiently release such large heat to the outside of the junction box 1.

  Further, as described above, in the junction box 1 of the present embodiment, sufficient heat dissipation is possible even if the heat conductive sheet 6 and the heat sink 7 are connected to only a part of the metal core substrate 2, so that the heat sink 7 is connected. It is possible to mount various mounting components on the surface on the side where the circuit board is mounted, and the mounting density of the circuit board can be increased.

  For example, as shown in FIGS. 1 to 5, in this embodiment, the heat conductive sheet 6 and the heat sink 7 are connected to the central area A <b> 3 on the first surface 2 a of the metal core substrate 2, and the areas A <b> 1 and A <b> 2 on both sides sandwiching the heat sink 7. Also, the board connector 3 can be mounted.

  Although it is most effective to arrange the heat conducting sheet 6 and the heat sink 7 in the central area A3 as in the present embodiment, the heat conducting sheet 6 and the heat sink 7 are arranged on the metal core board 2 because of the soaking characteristics of the metal core board 2. Can be set freely.

  For example, in the above description, the example in which the heat conductive sheet 6 and the heat sink 7 are connected to the central area A3 of the metal core substrate 2 and the components are mounted on the periphery thereof has been described, but the arrangement of the mounted components on the metal core substrate 2 is determined first. Thereafter, a heat radiating component such as the heat sink 7 may be connected to an empty space where no component is mounted in a predetermined shape matching the empty space. Thus, the junction box 1 of the present invention can have a high degree of freedom with respect to the circuit design of the metal core substrate 2.

  Next, the installation method of the heat sink 7 is demonstrated in detail using FIG. FIG. 6 is an enlarged view of a part of the junction box 1 including the heat sink 7. In the present embodiment, an opening 11a is provided in the center of the upper case 11, and the heat sink 7 is installed in the opening so as to be exposed to the outside. In this manner, the heat sink 7 is exposed to the outside of the upper case 11 (that is, the outside of the junction box 1), so that heat can be efficiently radiated.

  Moreover, the shape of the fixing | fixed part 13 of the upper case 11 which is fixing the edge part of the heat sink 7 is made into the labyrinth structure as shown in FIG. By adopting such a labyrinth structure for the fixing portion 13 of the upper case 11, the waterproof / dustproof effect is enhanced, and rainwater, dust and the like are less likely to enter the junction box 1.

Furthermore, in the junction box 1 of this embodiment, since components can be mounted on the same first surface 2a to which the heat sink 7 of the metal core substrate 2 is connected, tall components are mounted on the surface 2a. It is preferable to do so.
In FIG. 6, the tallest board connector 3 is mounted on the same surface as the heat sink 7 of the metal core board 2.

  As described above, by providing the heat sink 7 and the tallest substrate connector 3 on the same surface of the metal core substrate 2, the top of the upper case 11 and the tip of the heat sink 7 have the same height, Or it can comprise so that the front-end | tip part of the heat sink 7 may become lower. As a result, the height of the junction box 1 does not increase even when the tip of the heat sink 7 is exposed to the outside.

  Next, a circuit board built-in housing according to a second embodiment of the present invention will be described below with reference to FIGS. Here again, an automobile junction box will be described as an example of the circuit board built-in housing of the second embodiment.

  7-9 is a block diagram which shows the junction box 21 which becomes 2nd embodiment of this invention. 7 shows a side view of the junction box 21 as viewed from the side, FIG. 8 shows a top view as seen from above, and FIG. 9 shows a bottom view as seen from below.

  In the junction box 1 of the first embodiment described above, the heat sink 7 is used as a heat dissipation component. However, in the junction box 21 of the present embodiment, a heat pipe 22 is used as a heat dissipation component. The heat pipe 22 is provided with a heat collecting plate 24 at one end, and the heat collecting plate 24 is connected to the metal core substrate 2 through the heat conductive sheet 6 to collect heat soaked by the metal core substrate 2. To do. The other end of the heat pipe 22 is provided with a contact portion 23 to the body of the automobile, and the contact portion 23 is connected to the body of the automobile so as to release heat to the outside.

  Therefore, even when the heat pipe 22 is used, the same heat radiation effect as that when the heat sink 7 is used can be obtained. Similarly to the first embodiment, even if the heat conductive sheet 6 and the heat pipe 22 are connected to only a part of the metal core substrate 2, a predetermined heat dissipation effect can be realized. As a result, as in the case of the first embodiment, the placement of the mounted components on the metal core substrate 2 can be performed with a high degree of freedom.

  A circuit board built-in housing according to a third embodiment of the present invention will be described below with reference to FIG. Here again, an automobile junction box will be described as an example.

  FIG. 10 is a configuration diagram showing a junction box 31 according to the third embodiment of the present invention. In the junction box 31, the heat sink 7 is connected to one surface of the metal core substrate 2 via the heat conductive sheet 6, and the heat pipe 22 is connected to the other surface via the heat conductive sheet 6.

  As described in the first embodiment and the second embodiment, the metal core substrate 2 is used for the circuit board. Therefore, the heat conductive sheet 6 and the heat sink 7 or the heat pipe 22 are only part of the metal core substrate 2. It was possible to connect to. As a result, it was possible to arrange the mounted components on the surface of the metal core substrate 2 to which the heat conductive sheet 6 and the heat sink 7 or the heat pipe 22 are connected.

  Therefore, in the present embodiment, the heat sink 7 and the heat pipe 22 are connected to a part of each of both surfaces of the metal core substrate 2 via the heat conductive sheet 6, and the heat sink 7 and the heat pipe 22 are connected. The mounted parts are placed in positions that do not exist. This makes it possible to obtain a circuit board built-in housing with extremely high heat dissipation.

  Alternatively, it is also possible to appropriately dispose mounting components on both surfaces of the metal core substrate 2 and connect the heat sink 7 and the heat pipe 22 to the empty space on each surface via the heat conductive sheet 6. is there. In this case, a high degree of freedom can be obtained in the arrangement of the mounted components.

  Note that the description in the present embodiment shows an example of the circuit board built-in housing according to the present invention, and the present invention is not limited to this. The detailed configuration and detailed operation of the circuit board built-in housing in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

FIG. 1 is a side view of a junction box 1 as a circuit board built-in housing according to a first embodiment of the present invention as viewed from the side. FIG. 2 is a top view of the junction box 1 which is a circuit board built-in housing according to the first embodiment of the present invention as viewed from above. FIG. 3 is a bottom view of the junction box 1 which is a circuit board built-in housing according to the first embodiment of the present invention as viewed from below. FIG. 4 shows a cross-sectional view of the junction box 1 as seen in the AA cross section of FIG. FIG. 5 is a partially enlarged view of FIG. FIG. 6 is a diagram for explaining the installation method of the heat sink 7 in detail. FIG. 7 is a side view of the junction box according to the second embodiment of the present invention viewed from the side. FIG. 8 is a top view of the junction box according to the second embodiment of the present invention as viewed from above. FIG. 9 is a bottom view of the junction box according to the second embodiment of the present invention as viewed from below. FIG. 10 is a configuration diagram showing a junction box according to the third embodiment of the present invention. FIG. 11 is a view showing a heat dissipating means having a structure provided with a conventional heat dissipating fin.

Explanation of symbols

1, 21, 31 ... Junction box 2 ... Metal core board 3 ... Board connector 4 ... Fuse holder 5 ... ECU
6 ... Thermal conductive sheet 7 ... Heat sink 8 ... Terminal 9 of substrate connector 3 ... Fuse terminal 10 ... Semiconductor relay 11 ... Upper case 12 ... Lower case 13 ... Fixed Part 22 ... Heat pipe 23 ... Contact surface 41 ... Core material 41
42 ... Insulation coating 43 ... Through hole 44 ... Copper foil part 45 ... Circuit pattern 47 ... Solder 48 ... Solder resist 101 ... Electronic component 102 ... Circuit board 103 ..Heat radiation sheet 104 ... Heat radiation fin 105 ... Case 106 ... Sealing plastic

Claims (3)

A circuit board built-in housing in which a circuit board having a first surface and a second surface is built in a case,
A metal core substrate is used for the circuit board,
A heat conductive sheet fixed to the first surface of the metal core substrate;
Of the heat conductive sheet, wherein the metal core fixing surface of the substrate is fixed to the opposite face, e Bei a heat radiator in which a plurality of projections protrudes,
The heat dissipating component is installed in a partially exposed state outside the case through an opening provided in the case,
The portion of the case that fixes the heat dissipating part has a labyrinth structure that extends beyond at least one of the plurality of protrusions of the heat sink and extends to a bottom portion between the protrusions. A circuit board built-in housing. Through holes are formed in the metal core substrate,
Mounted components are arranged on the second surface of the metal core substrate,
In the through hole, the terminal of the mounting component is inserted and fixed in a state where the tip protrudes from the first surface,
The heat conductive sheet is made of an insulating material and is formed with a thickness exceeding the tip length of the terminal protruding from the metal core substrate.
The circuit board built-in housing according to claim 1. On the surface of the metal core substrate on which the terminal protrudes, the connectors are surface-mounted in opposed states on opposite side edge areas,
The circuit board built-in case according to claim 1, wherein the heat conductive sheet is disposed in a central area between the connector mounting areas.