JP2001298294A - Shield structure of electronic unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a low-cost electronic unit shield structure wherein assembly work is easy and the radiation noise from a power circuit to a control board is reduced. SOLUTION: An electronic unit 40 comprises a control board 20 and a relay 14 electrically connected together, which is housed in a housing case where an upper case 11 and a lower cover 23 are coupled. The relay 14 is provided on a flat plate 15a of a shield plate 15 which is provided above the control board 20 and shields radiation noise generated from the relay 14. The terminal of relay 14 is electrically connected to the control board 20 through a flexible printed board 21 comprising a connection part which is electrically connected and fixed to the terminal penetrating a through hole while bonded to the rear surface of the flat plate 15a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shield structure of an electronic unit having a control board and power circuit components electrically connected to each other.

[0002]

2. Description of the Related Art Conventionally, as an electronic control unit (ECU) used in an electric wiring system of a vehicle or the like, a circuit board in which an electrically connected control board and a power circuit component are housed in a housing case. Is used. A conventional electronic unit 1 shown in FIG. 5 includes a relay 4 as a power circuit component and an IC chip on a connection board 3 in which a bus bar circuit 2 having a plurality of connection tab terminals 2a is integrally molded in an insulating resin. The control board 5 and the like on which the components are mounted are placed and electrically connected. The electronic unit 1 is an electronic unit box housed in a synthetic resin housing case (not shown) for protection from dust, water and the like, for example, an electric connection box (junction box) placed in an engine room. And so on.

Further, a plurality of components such as the relay 4 and the control board 5 mounted on the connection board 3 are arranged as close as possible to each other in order to reduce the size of the electronic unit 1. In particular, the power circuit components such as the relays 4 have a large volume in order to withstand a large current, and most of the portions on the connection board 3 are areas for mounting the plurality of relays 4. . Therefore, the rectangular flat control board 5
As shown in FIG. 5, is mounted between the plurality of relays 4 arranged in two rows in an upright state on the connection board 3.

The electronic unit box in which the electronic unit 1 is housed in a sealed housing case as described above has a poor heat radiation property and the relay 4 as a power circuit component.
Becomes hot due to the heat generated by the relay. Therefore, conventionally, for example, the heat of the relay 4 is radiated to the outside of the case via the connection tab terminal 2a of the bus bar circuit 2.

[0005]

However, since the heat radiation from the bus bar circuit 2 in the electronic unit 1 is localized and it is difficult to radiate the heat at a uniform temperature, a sufficient heat radiation effect cannot be obtained. . Therefore, when assembling the relay 4 on the connection board 3 and electrically connecting the terminals of the relay 4 to the bus bar circuit 2, the terminals of the relay 4 inserted through the through holes of the bus bar circuit 2 are added. After tightening, it was necessary to solder or connect by welding.

That is, the relay 4 is mounted on the connection board 3 and the terminals of the relay 4 through which the through-holes of the bus bar circuit 2 are inserted are soldered, so that the relay 4 is mounted.
Simply connecting the terminal to the land portion of the bus bar circuit 2 may cause solder cracks due to the thermal shock of the terminal expanding and contracting due to the heat generated by the relay, which may cause a reduction in the reliability of the electrical connection.

The control board 5 mounted on the connection board 3 so as to be surrounded by a plurality of relays 4 is susceptible to radiant heat and radiated noise of the relays 4. Therefore, it has been necessary to take heat measures such as applying a heat-resistant coating around the control board 5 so that the IC chip and the like on the board do not cause characteristic fluctuation or thermal destruction due to excessive heat rise.

On the other hand, in order to prevent the radiation noise of the relay 4 from leaking out of the case, noise measures such as using a metal case for the housing case have been conventionally taken. There is no effective noise countermeasure for the accommodated control board 5. That is, the conventional electronic unit requires a complicated assembling operation and a complicated structure as described above in order to guarantee a stable operation corresponding to a rise in temperature due to the heat generated by the relay 4, resulting in an increase in cost. In addition, there is a possibility that the control board 5 may malfunction due to the influence of the radiation noise of the relay 4.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problem, and it is easy to assemble the shield structure of an inexpensive electronic unit which can easily assemble and reduce noise radiated from power circuit components to a control board. It is to provide.

[0010]

An object of the present invention is to provide a shield structure of an electronic unit having a control board and a power circuit component electrically connected to each other, wherein the power circuit component is provided on the control board. Is disposed on a shield plate for shielding radiated noise generated by the power circuit component, and terminals of the power circuit component are attached to at least a back surface of the shield plate. A shield that is electrically connected to the control board via a flexible printed circuit board having a connection portion that is electrically connected to and fixed to the terminal penetrating through the through hole of the electronic unit. Achieved by structure.

[0011] According to the above configuration, since the power circuit component is provided on the shield plate disposed above the control board, the power circuit component in the case below the power circuit component with the shield plate interposed therebetween. The control board accommodated in the
Radiation heat and radiated noise generated by the power circuit component can be hardly received.

In the power circuit component, only the terminal is fixed to the connection portion of the flexible printed circuit board having flexibility, and is not fixed to the shield plate. Therefore, even if the soldered terminal expands and contracts due to heat. In addition, solder cracks due to thermal shock can be reduced, and there is no risk of lowering the reliability of electrical connection. Therefore, it is not necessary to perform a troublesome assembling operation such as performing soldering after crimping the terminal of the power circuit component or connecting by welding.

Further, heat transmitted to the terminal of the power circuit component is transmitted from the terminal to a connection portion of the flexible printed circuit board adhered to the shield plate, and can be radiated to the shield plate. Therefore, the heat of the terminal of the power circuit component, which has the highest temperature, can be uniformly and stably radiated to the shield plate through the connection portion of the flexible printed circuit board stuck to the shield plate. It can also be suppressed efficiently.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a shield structure of an electronic unit according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an exploded perspective view of an electronic unit box accommodating an electronic unit according to an embodiment of the present invention, FIG. 2 is a perspective view of a shield plate and a control board shown in FIG. 1, and FIG. FIG. 4 is a longitudinal sectional view showing an assembled state of the unit box, and FIG. 4 is a transverse sectional view of the electronic unit box shown in FIG.

The electronic unit box 1 according to the present embodiment
0, as shown in FIG. 1, after storing the electronic unit 40 in a storage case combining the upper cover 11 made of synthetic resin and the lower cover 23, for example, a predetermined junction box or the like placed in an engine room. Is attached to the attachment portion 50 of the.

The electronic unit 40 includes a control board 20 and a relay 14 that is a power circuit component, which are electrically connected to each other, and achieves electrical connection when the electronic unit 40 is mounted on the mounting portion 50. Terminal holder 17. Further, the relay 14 has a flat plate portion 15 of a shield plate 15 for shielding radiation noise generated by the relay 14.
a through-hole 15c of the flat plate portion 15a.
Is electrically connected to the control board 20 via a flexible printed circuit board (FPC) 21 described later (see FIG. 3).

As shown in FIGS. 1 and 2, the shield plate 15 is made of a conductive material such as an aluminum alloy plate, and is provided on both sides of a flat plate portion 15a on which a plurality of relays 14 arranged in two rows are provided. The edges are bent at substantially right angles, so that a pair of shield side walls 15b, 15b is erected along the outer side surfaces of the relays 14 in the row direction. Incidentally, the shield plate 15 is not limited to a metal plate such as an aluminum alloy, and various conductive materials can be used.
For example, it can be integrally molded with a synthetic resin to which a metal filler is added. Preferably, the shield plate 15 is used.
Is coated with a black insulating coating (insulating coating).

As shown in FIGS. 2 and 3, the flexible printed circuit board 21 has a connecting portion 21a attached to the back surface (the lower surface in the figure) of the flat plate portion 15a on which the relay 14 is provided. Circuit section 21 on which IC chip 31 and the like are mounted
b, and a flexible connecting portion 21c for electrically connecting the connecting portion 21a and the circuit portion 21b. The circuit section 21b is attached to a rectangular board-shaped hard board 20a to form the control board 20.

Each land portion of the connection portion 21a is
As shown in FIG. 4 to FIG.
The terminal 14a of each relay 14 and the connection tab terminal 18 of the terminal holder 17 that pass through 5c are appropriately soldered and electrically connected. Here, the through hole 15c
The terminal 1 penetrated as shown in FIG.
4a has a sufficient inside diameter and does not contact each other.

The connection tab terminals 18 are integrally molded in a predetermined arrangement (in this embodiment, two rows) in a holder main body 17a made of an insulating resin, and a tip portion thereof is located below the holder main body 17a. And the base end is exposed flush with the upper surface of the holder body 17a. However, as shown in FIG. 4, at least one of the connection tab terminals 18 has a base end penetrated through the connection portion 21a and is electrically connected to the flat plate portion 15a.
Are connected to a ground wire (not shown) provided in the power supply unit.

As shown in FIG. 3, the control board 20 is inverted so that the connecting portion 21c is curved in a U-shape while being substantially parallel to the connecting portion 21a with the flat plate portion 15a interposed therebetween. After that, it is locked and fixed by locking claws 17b protruding from the lower surface of the holder main body 17a. That is, the relay 14 is placed on the flat plate portion 15a of the shield plate 15 placed above the control board 20.

The lower cover 23 is connected to the terminal holder 17.
Connection tab terminal 18 and shield ground terminal 18a
Is provided with a terminal accommodating portion 26 capable of accommodating therein. On the mounting surface side of the lower cover 23 to which the electronic unit 40 is mounted, a plurality of insertion ports 27 communicating with the terminal receiving chamber in the terminal receiving portion 26 are formed, and a locking and fixing member for locking the electronic unit 40 is provided. A stop claw 24 and a locking claw 25 for locking and fixing the upper cover 11 are protrudingly provided.

Then, when the electronic unit 40 is mounted on the mounting surface of the lower cover 23 by inserting the connection tab terminal 18 and the shield ground terminal 18a into the insertion opening 27, the locking claw 24 is By locking both longitudinal edges of the electronic unit 15a, the electronic unit 40
Are integrally attached to the lower cover 23. When the lower cover 23 and the upper cover 11 are combined in this state, the locking claws 25 are engaged with the engagement holes 19 of the upper cover 11, and the electronic unit box 10 is assembled.

Further, when the electronic unit box 10 of this embodiment accommodates the electronic unit 40 and combines the lower cover 23 and the upper cover 11, as shown in FIG. Fifteen
A heat radiation structure is defined in which a ventilation space composed of a plurality of ventilation holes 30 is defined between b and 15b facing the side walls 11a and 11a of the upper cover 11.

Each of the ventilation holes 30 is defined by a plurality of partition walls 13 projecting from the inner surface of the side wall 11a, and each of the upper openings 12 formed in the top plate of the upper cover 11.
And the lower opening 16 formed between the lower end edge of the side wall 11a and the butted portion of the lower cover 23, and communicates with the outside of the case. As shown in FIG. 4, the upper edge of the side wall 15b for heat radiation has an upper cover 1
1 is fitted into the fitting groove 11b provided in the inner wall of the opposing top plate, and the side edge is in contact with the inner surface of the opposing side wall of the upper cover 11; It is discharged from the lower opening 16 without entering the relay 14 side.

That is, according to the shield structure of the electronic unit 40 of the present embodiment, the relay 14
Is fixed on the flat plate portion 15a of the shield plate 15 disposed above the control board 20, so that the control board 20 housed in the housing case below the relay 14 with the flat plate portion 15a interposed therebetween Radiated heat and radiated noise generated by the laser can be reduced.

Further, in the shield plate 15 of the present embodiment, a pair of shield side walls 15b, 15b is erected along the outer surface in the row direction of the relays 14, and surrounds the sides of the relays 14. Therefore, radiant heat and radiated noise to the control board 20 generated by these relays 14 can be further reduced.

In the relay 14, only the terminal 14a is fixed to the connection portion 21a of the flexible printed circuit board 21 having flexibility, and is not fixed to the flat plate portion 15a of the shield plate 15. Even if 14a is expanded and contracted by heat, solder cracks due to thermal shock can be reduced, and there is no danger of lowering the reliability of electrical connection. Therefore, as shown in FIG. 3 (b), it is only necessary to solder the terminal 14a to the land of the connection portion 21a, and after crimping the terminal 14a of the relay 14, soldering or welding is performed. There is no need for complicated assembly work such as connection.

In addition, the heat transmitted to the terminal 14a of the relay 14 is transmitted from the terminal 14a to the connecting portion 21a of the flexible printed circuit board 21 attached to the flat plate portion 15a of the shield plate 15, and to the flat plate portion 15a. Since the heat is dissipated, the heat is released from the shielding side wall portion 15b of the shield plate 15 to the air flowing through each ventilation hole 30.

The ventilation hole 30 communicates with the outside of the case through the upper and lower openings 12 and 16 as described above.
A natural convection that causes the air flowing in from 6 to flow out from the upper opening 15 is generated. Therefore, the shield side wall portion 15b
Is uniformly and stably cooled by the air flowing through the ventilation holes 30, and the heat generated by the relay 14 can be efficiently radiated to the outside of the case.

Therefore, the control board 20 is coated with a heat-resistant coating like the conventional control board 5 shown in FIG. 5 in combination with the improvement of the heat radiation efficiency of the heat generated by the relay 14 to the outside of the case. This eliminates the need for heat measures, and can suppress an increase in cost.

Incidentally, the configurations of the power circuit components, the control board, the shield plate and the flexible printed board in the shield structure of the electronic unit of the present invention are not limited to the configuration of the above embodiment, but are based on the spirit of the present invention. Needless to say, various forms can be adopted. For example, the power circuit component is not limited to the relay 14, but is also effective for other power circuit components that generate radiation noise such as switching noise and spike noise.

Further, in the above embodiment, the connecting portion 21a attached to the back surface of the flat plate portion 15a and the circuit portion 2a
1b and the flexible printed circuit board 21 having the connecting portion 21c for electrically connecting them are used. However, at least the connecting portion attached to the back surface of the flat plate portion 15a may be constituted only by the flexible printed circuit board.
The connection portion and the control board can be electrically connected by a ribbon wire or the like. Further, the means for connecting the shield plate to a ground wire (not shown) is not limited to the configuration of the shield ground terminal 18a in the above-described embodiment, but may employ various known configurations.

[0034]

According to the shield structure of the electronic unit of the present invention, since the power circuit component is disposed on the shield plate disposed above the control board, the power circuit component is disposed on both sides of the shield plate. The control board housed in the case below the components can be made less susceptible to radiant heat and radiation noise generated by the power circuit components.

Further, in the power circuit component, only the terminal is fixed to the connection portion of the flexible printed circuit board having flexibility, and is not fixed to the shield plate. Therefore, even if the soldered terminal expands and contracts due to heat. In addition, solder cracks due to thermal shock can be reduced, and there is no risk of lowering the reliability of electrical connection. Therefore, troublesome assembling work such as soldering after crimping the terminal of the power circuit component or connection by welding is not required.

Further, heat transmitted to the terminal of the power circuit component is transmitted from the terminal to a connection portion of the flexible printed circuit board adhered to the shield plate, and can be radiated to the shield plate. Therefore, the heat of the terminal of the power circuit component, which has the highest temperature, can be uniformly and stably radiated to the shield plate through the connection portion of the flexible printed circuit board stuck to the shield plate. It can also be suppressed efficiently.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an electronic unit box that houses an electronic unit according to an embodiment of the present invention.

FIG. 2 is a perspective view of a shield plate and a control board shown in FIG.

3A is a longitudinal sectional view showing an assembled state of the electronic unit box shown in FIG. 1, and FIG. 3B is an enlarged view of a main part thereof.

4A is a cross-sectional view of the electronic unit box shown in FIG. 3, and FIG. 4B is an enlarged view of a main part thereof.

FIG. 5 is an overall perspective view of a conventional electronic unit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 electronic unit box 11 upper cover 14 relay (power circuit component) 15 shield plate 15 b shielding side wall 17 terminal holder 20 control board 21 flexible printed board 23 lower cover 40 electronic unit

Claims (1)

[Claims] 1. A shield structure of an electronic unit including a control board and a power circuit component electrically connected to each other, wherein the power circuit component is disposed above the control board, and The terminal of the power circuit component is disposed on a shield plate that shields generated radiation noise, and the terminal of the power circuit component is electrically connected to the terminal that is attached to at least the back surface of the shield plate and passes through a through hole of the shield plate. A shield structure of the electronic unit, wherein the shield structure is electrically connected to the control board via a flexible printed circuit board having a connection portion which is connected and fixed to the electronic unit.