JPH08274421A - Electronic circuit unit - Google Patents

Abstract

PURPOSE: To realize compact and inexpensive constitution for heat dissipation of a heat generating electronic device and simplify the manufacturing process of an electronic circuit unit. CONSTITUTION: In an electronic circuit unit wherein an electronic device is mounted on a board 19 of an electronic circuit, bus bars 16, 17, 18 are arranged on a board and a bus bar is connected to a conductive material constituting an electronic circuit on a board for constituting a circuit consisting of a conductive material 20 and the bus bars 16, 17, 18. A terminal 12a of a heat generating electronic device 12 such as a power transistor among electronic devices is connected to a bus bar of a circuit and heat generated in an electronic device is dissipated by the circuit bus bars 16, 17, 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic circuit unit, and more particularly to a structure for radiating heat generated by an electronic device mounted on a substrate of the electronic circuit unit, which can be downsized.

[0002]

2. Description of the Related Art An electric connection box used for a wire harness for an automobile has an electronic circuit unit built in the case,
In some cases, an internal circuit such as a bus bar housed in the case is connected to an electronic circuit to form a high density and concentrated branch circuit. Conventionally, many electronic circuits built in this kind of electrical junction box have signal system circuits such as an alarm circuit for forgetting to turn off the lamp, and electronic devices mounted on the board generate a small amount of heat.
Moreover, since the electronic circuit is a small current circuit and generates a small amount of heat, it is not necessary to take heat dissipation measures.

However, in recent years, in many cases, a power transistor having functions such as a fuse and a relay integrated is mounted on a substrate of an electronic circuit, and the power transistor has a large amount of heat generation and the power transistor is large. Since the electronic circuit connected to is also a large current circuit, the amount of heat generated is large.

Therefore, it is necessary to take measures against heat radiation. In the first prior art, as shown in FIG. 5, a large heat radiation plate 1 is attached to an electronic device A such as a power transistor which generates a large amount of heat.

A second conventional technique (Japanese Patent Laid-Open No. 61-46)
098), the heat transfer member attached to the power transistor with a bolt is brought into contact with the connector pin of the connector installed on the substrate on which the power transistor is mounted,
The heat of the power transistor is conducted to the connector pin via the heat transfer member to radiate the heat.

[0006] In addition, the third prior art (Actual Kaihei 5-781)
In 26), a heat-generating intelligent power switch mounted on the board is connected to a conductive material on the board to form a circuit, while the power switch is fixed on the board with a bus bar and bolts that are arranged only for heat dissipation. Alternatively, they are engaged with each other in a locking manner and thermally and mechanically coupled to each other, and the heat generated by the power switch is conducted to the bus bar to radiate the heat.

[0007]

However, in the above-mentioned first prior art, the large heat dissipation plate 1 has the electronic circuit unit 3
Since it is installed so as to stand upright from the substrate 4 in the vertical direction, the thickness of the electronic circuit unit 3 in the vertical direction becomes large, and the installation space for the electronic circuit unit 3 becomes large. Further, when the electronic circuit unit 3 is built in the electric connection box, there is a problem that the electric connection box becomes large. In particular, since the electric junction box is often installed in a narrow space of an automobile, it is necessary to prevent the electric junction box from increasing in size.

The radiator plate 1 is attached to the electronic device A in advance by fixing the radiator plate 1 with the pin 2, and when the electronic device A is installed on the substrate 4, the engaging claw 1a of the radiator plate 1 is fixed. Since it is necessary to engage with the engaging hole 4a of the substrate 4, there is a drawback that the work of attaching the heat dissipation plate 1 is troublesome. Further, if a large heat dissipation plate is used for each electronic device, the number of parts increases and the cost increases.

Also, in the second conventional technique, the work of fixing the heat transfer member to the power transistor with a bolt is required, and the mounting work is troublesome.

In the third prior art described above, it is necessary to provide a heat-dissipating bus bar separately from the bus bar that is connected to an electronic device to form a circuit. Moreover, when fixing the intelligent power switch to the bus bar with bolts, bolting work is required, which makes mounting work troublesome. Further, in the case of locking and fitting, it is necessary to previously provide a female terminal with which the tab of the bus bar can be fitted and contacted in the manufacturing process of the power switch, which has a disadvantage of increasing the manufacturing cost of the power switch.

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned drawbacks, and it is an object of the present invention to make the structure for heat dissipation of a heat-generating electronic device small and inexpensive and to simplify the manufacturing process of an electronic circuit unit. There is.

[0012]

In order to achieve the above-mentioned object, according to the present invention, in claim 1, in an electronic circuit unit having electronic equipment mounted on a substrate of an electronic circuit, a bus bar is arranged on the substrate, The bus bar is connected to a conductive material forming an electronic circuit on a substrate to form a circuit composed of the conductive material and the bus bar, and the bus bar of the circuit has a heat-generating electronic device such as a power transistor among the electronic devices. There is provided an electronic circuit unit characterized in that the terminals are connected and heat generated in an electronic device is conducted to the bus bar.

The bus bar may be bent in a bridge shape so that a required gap may be formed between the bus bar and the substrate surface in a required region, and an electronic device may be arranged in the gap. (Claim 2)

Further, when the electronic circuit unit is not built in an electric connection box such as a junction box, connected to a bus bar housed in the electric connection box, and an external circuit is connected through the bus bar, that is, When the electronic circuit unit is housed alone in the case, a tab for connecting an external circuit is provided on the bus bar, and a terminal connected to the wire harness of the external circuit is connected to the tab. (Claim 3)

To connect the bus bar on the board to the conductive material, a projecting piece refracted from the bus bar arranged on one surface of the board is provided, and the projecting piece is passed through a mounting hole formed in the board to connect the board to another board. Connected by soldering with a conductive material provided on the surface, simultaneously fixing the bus bar to the substrate by the soldering, and insert the terminal of the electronic device into the through hole formed in communication with the bus bar and the substrate, It is preferable that the bus bar is connected by soldering. (Claim 4)

The electronic circuit unit may be built in an electric connection box such as a junction box in which a bus bar is laminated in a case, and a conductive material of an electronic circuit may be connected to the bus bar. (Claim 5)

[0017]

According to the electronic circuit unit of the present invention, the bus bar arranged on the substrate is electrically connected to the conductive material arranged on the substrate and the terminal of the heat-generating electronic device, It forms a part of the circuit of the circuit unit and is also connected to the terminals of the electronic device so as to be able to conduct heat, and also serves as a heat dissipation plate. Since the bus bar arranged on the board is arranged along the surface of the board, the thickness of the electronic circuit unit is not increased by providing the bus bar. The heat of the exothermic electronic device is conducted from the terminal to the bus bar and radiated. Therefore, instead of the conventional large heat sink, the bus bar radiates heat from the heat-generating electronic device, so the electronic circuit unit can be made thinner by removing the large heat sink, and the electronic circuit unit can be made smaller. it can.

According to another aspect of the electronic circuit unit of the present invention, the bus bar is bent in a bridge shape so that a required space is provided between the bus bar and the substrate surface in a required region. In the above required area, the electronic device can be mounted between the board and the bus bar, and the area on the surface of the board can be effectively used.

According to the electronic circuit unit of the third aspect, the bus bar is provided with a tab, and a connector of an external circuit such as a wire harness is connected to the tab. By providing the tab, the electronic circuit unit can be easily connected to an external circuit.

According to the electronic circuit unit of the fourth aspect, the electrical connection between the bus bar and the conductive material and the fixing of the bus bar to the substrate can be simultaneously performed by one soldering. Further, the connection between the bus bar and the electronic device and the fixing to the board can be easily performed by inserting the terminals of the electronic device into the through holes of the bus bar and the board and soldering them.

According to the electronic circuit unit of the fifth aspect, when the electronic circuit unit is built in a case of an electric connection box such as a junction box, the bus bar housed in the electric connection box can also be used as a heat dissipation plate and effectively generated from the electronic device. It can dissipate heat.

[0022]

The present invention will be described in detail below with reference to the embodiments shown in the drawings. First shown in FIGS. 1, 2 and 3
The electronic circuit unit 11 of the embodiment is a PCB (print
Electronic devices such as a power transistor 12, resistors 13, 14 and a consensus 15 are mounted on the upper surface of a substrate 19 of a circuit board). An electronic circuit is provided by printing a conductive material 20 on the lower surface of the substrate 19 with a thickness of several tens of μm, and an insulating film 21 is coated on the upper surface thereof.
A plurality of busbars 16, 17, 18 are provided on the upper surface of the substrate 19, and these busbars 16, 17, 18 are connected to a required conductive material 20 to form a part of a circuit. Also, it is connected to the terminal 12a of the power transistor 12 that generates a large amount of heat, is used as a circuit to the power transistor 12, and also radiates heat.

As shown in FIG. 3, the substrate 19 has a through hole 19a through which the terminal 12a of the power transistor 12 is inserted, and a plurality of through holes 19b through which the terminals of the resistors 13 and 14 and the consensus 15 are inserted. , The bus bar 1 described later
A plurality of mounting holes 19c through which the projecting pieces 16c, 17c, 18c of 6, 17, 18 are inserted are formed.

At the peripheral portions of the through hole 19b and the mounting hole 19c on the lower surface side of the substrate 19, the insulating film 21 is removed to expose the conductive material 20, and the terminals of the resistors 13 and 14 and the capacitor 15 are inserted into the through hole 19b. Exposed conductive material 2
It is connected to 0 with solder. On the other hand, as shown in FIG. 2, the conductive material 20 is not provided in the peripheral portion of the through hole 19a, and the terminal 1 of the power transistor 12 to be inserted into the through hole 19a.
2a is not in contact with the conductive material 20.

Each bus bar 16 disposed on the substrate 19,
17 and 18 are formed by punching out a conductive metal plate similarly to the conventional bus bar, and are formed by the flat plate portions 16b, 17b, 18b arranged in parallel with the upper surface of the substrate 19 and the flat plate portions 16b, 16b.
Each of the flat plate portions 16b, 1 is composed of a plurality of projecting pieces 16c, 17c, 18c that are bent at right angles from the edges of the 17b, 18b.
Through holes 16a, 17a, and 18a are formed in 7b and 18b, respectively, through which the terminal 12a of the power transistor 12 is inserted.

The flat plate portion 17b of the bus bar 17 is provided with a bridge portion 17d which is bent at its central portion into a bridge shape and which projects in a direction away from the upper surface of the substrate 19. A required gap is formed between the bridge portion 17d and the surface of the substrate 19, and electronic devices such as resistors 13 and 14 are mounted under the bridge portion 17d.

The bus bar 17 has tabs 17 for connecting external terminals which extend from the edge of the flat plate portion 17b in the direction opposite to the protruding piece 17c, that is, in the direction away from the surface of the substrate 19.
e is protruding. The tab 17e is the electronic circuit unit 11
Is pierced through the top plate of the case in which it is housed so as to project into the connector provided on the outer surface of the case so as to be connected to a terminal of an external circuit such as an automobile wire harness.

The attachment of the bus bars 16, 17, 18 to the substrate 19 and the connection between the bus bars 16, 17, 18 and the power transistor 12 are performed in the following steps.

First, for electronic devices such as the resistors 13 and 14 and the capacitor 15 that do not need to dissipate heat, the terminals of these electronic devices are inserted into the through holes 19b of the substrate 19 and installed on the substrate 19. Next, the projecting pieces 16c, 17c, 18c of the bus bars 16, 17, 18 are inserted into the mounting holes 19c of the board 19 to set the bus bars 16, 17, 18 on the board 19. At this time, the through holes 19 of the substrate 19 corresponding to each other
a and through holes 16a, 17a, 1 of each bus bar 16, 17, 18
It communicates with 8a.

Subsequently, the terminals 12a of the power transistor 12 are connected to the through holes 16a, 16b of the bus bars 16, 17, 18, respectively.
The power transistor 12 is set on the substrate 19 by inserting the power transistor 12 into the through holes 19a of the substrate 19 via 17a and 18a.

After all the electronic devices and the bus bars 16, 17 and 18 have been installed on the substrate 19 as described above, the terminals 12a of the power transistor 12 protruding to the back side of the substrate 19
Terminals such as resistors 13 and 14, and bus bars 16 and 17,
The projecting pieces 16c, 17c, 18c of 18 are soldered to the substrate 19. By soldering, through holes 19a, 1
9b and the mounting hole 19c are filled with the solder 22, and the solder 22 is filled with the through holes 19a and 19b and the mounting hole 19c.
Of the power transistor 12 from the upper and lower peripheral portions of the power transistor 12 so as to sandwich the substrate 19 on the surface of the substrate 19.
The terminals of the electronic device such as a, the resistors 13 and 14 and the projecting pieces 16c, 17c and 18c of the bus bars 16, 17 and 18 are fixed to the substrate 19 so as not to come off.

At the same time, the terminals of the electronic equipment such as the resistors 13 and 14 and the protruding piece 1 of the busbars 16, 17 and 18 are provided.
6c, 17c and 18c are electrically connected to the conductive material 20 provided on the lower surface of the substrate 19 by solder 22. Also,
Solder 22 is mounting hole 16c, 17 of bus bar 16, 17, 18
The solder 12 also causes the terminal 12a of the power transistor 12 to flow into the busbars 16, 17, 18c.
Is electrically and thermally conductively connected.

In the electronic circuit unit 11 having the above structure, the circuit connected to the power transistor 12 is composed of the conductive material 20 on the substrate 19 and the bus bars 16, 17, and 18.
The power transistor 12 has a bus bar 1 rather than a conductive material 20.
Current flows through 6, 17, and 18. Moreover, since the heat is generated from the power transistor 12, the heat generated by the power transistor 12 is connected to the bus bars 16, 17, and 18.
From the terminal 12a of the bus bar 16,1 via the solder 22
It is conducted to 7, 18 and is radiated from the bus bars 16, 17, 18.

As described above, the bus bar 1 forming the circuit
Since 6, 17, 18 are used as heat sinks, and these bus bars are flat plate members arranged in parallel with the substrate 19,
The electronic circuit unit 11 and the case in which the electronic circuit unit 11 is housed can be significantly downsized particularly in the thickness direction, that is, the vertical direction in FIG.

Although the electronic circuit is not provided on the upper surface of the substrate 19 in the above-mentioned embodiment, the electronic circuit may be formed in a region where the bus bar is not provided. Alternatively, when the bus bar is provided with a bridge portion separated from the upper surface of the substrate, an electronic circuit may be formed below the bridge portion. Further, when the insulating film of the electronic circuit is made of a heat resistant material, the bus bar may be arranged on the upper surface of the electronic circuit.

In the second embodiment shown in FIG. 4, an electronic circuit unit is built in an electric junction box 31 composed of a junction box. That is, in the electrical connection box 31, the bus bar 34 is stacked and arranged over the entire area of the case formed of the upper case 32 and the lower case 33 with the insulating plate 35 interposed therebetween.
The electronic circuit unit 11 is built in. On the upper right side of the upper case 32, a stepped protrusion 32a into which the electronic circuit unit 11 is fitted is provided.

In this embodiment, the bus bar 34 and the bus bar 1 arranged on the substrate 19 of the electronic circuit unit 11 are arranged.
It is formed separately from 6, 17, and 18. The conductive material 20 and the bus bar 34 of the electronic circuit unit 11 are the same as the bus bar 34.
Circuit portion 34 extending below the electronic circuit unit 11 of
A tab 34b is formed at each tip of a by bending in the direction of the electronic circuit unit 11, and the tab 34b is inserted into each tab insertion portion of the connector 23 mounted on the upper surface of the board 19 through a mounting hole formed in the board 19. Electrically connected by. The connector 23 accommodates a plurality of terminals (not shown) connected to the conductive material 20.
Connected by contacting with b.

As described above, the power transistor 12 of the electronic circuit unit 11 includes the bus bar 34 on the electric junction box side,
It is connected to a circuit composed of the conductive material 20 on the substrate 19 and the bus bars 16, 17, and 18 connected to the conductive material 20, and is connected to an external circuit via an external circuit connecting terminal provided on the bus bar 34. Therefore, the bus bar 16 and the like on the substrate 19 are not provided with tabs for connecting an external circuit.

With the above configuration, the power transistor 1
First, the heat generated in 2 is generated by the bus bar 16 on the substrate 19,
The heat can be radiated from 17, 18 and is also conducted to the bus bar 34 on the electric junction box side through the conductive material 20, and the heat is also radiated from the bus bar 34.

[0040]

As is apparent from the above description, in the electronic circuit unit according to the first aspect of the present invention, instead of the conventional large-sized heat dissipation plate, the bus bar forming the circuit is used to generate heat. Since the heat is dissipated, the thickness of the electronic circuit unit can be reduced and the electronic circuit unit can be downsized. As a result, it can be easily installed in a small area inside such as an automatic electrical junction box, which requires miniaturization.
Further, since the conventional large-sized heat dissipation plate is removed and the bus bar forming a part of the circuit is also used as the heat dissipation plate, the number of parts can be reduced and the structure for heat dissipation can be made inexpensive. As a result, the electronic circuit unit can be manufactured at low cost.

In the electronic circuit unit of claim 2, since the bus bar is bent in a bridge shape, an electronic device can be mounted between the substrate and the bus bar, and the area on the surface of the substrate can be effectively used. . As a result, the mounting density of electronic devices on the substrate surface can be increased, and the substrate can be miniaturized accordingly.

In the electronic circuit unit according to the third aspect, by providing the tab on the bus bar, the electronic circuit unit can be easily connected to the external circuit. In addition, connection work and disconnection work between the electronic circuit unit and the external circuit can be facilitated.

In the electronic circuit unit according to the fourth aspect, the electrical connection between the bus bar and the heat-generating electronic device and the fixing of the bus bar and the substrate can be performed at the same time. Therefore, as compared with the conventional work of connecting the heat-generating electronic device using a bolt or the like to the heat sink or the bus bar, the work of mounting the bus bar can be greatly simplified.

In the electronic circuit unit according to the fifth aspect, the electric connection box can be downsized by the size of the built-in electronic circuit unit, and as a result, the electric connection box can be installed even in a narrow area such as an automobile. Can be installed easily.

[Brief description of drawings]

FIG. 1 is a perspective view showing a configuration of an electronic circuit unit according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a partial configuration of the electronic circuit unit of FIG.

FIG. 3 is an exploded perspective view of the electronic circuit unit of FIG.

FIG. 4 is a perspective view showing a configuration of an electric junction box according to a second embodiment of the present invention.

FIG. 5 is a perspective view showing a partial configuration of a conventional electronic circuit unit.

[Explanation of symbols]

 11,11a Electronic circuit unit 12 Power transistor 16,17,18,34 Bus bar 19 Substrate 20 Conductive material constituting electronic circuit 21 Insulating film 22 Solder 31 Electrical connection box 35 Insulating plate

Claims (5)

[Claims] 1. An electronic circuit unit in which an electronic device is mounted on a board of an electronic circuit, wherein a bus bar is arranged on the board, and the bus bar is connected to a conductive material forming an electronic circuit on the board to form a conductive material. And a bus bar, and a terminal of a heat-generating electronic device such as a power transistor of the electronic device is connected to the bus bar of the circuit to conduct heat generated by the electronic device to the bus bar. An electronic circuit unit characterized by the above. 2. The bus bar is bent in a bridge shape so that a gap is formed between the bus bar and a surface of the substrate in a required area, and an electronic device can be arranged in the gap. Electronic circuit unit as described. 3. The electronic circuit unit according to claim 1, wherein the bus bar is provided with a tab for connecting an external circuit. 4. A projecting piece bent from a bus bar arranged on one surface of the board is provided, the projecting piece is passed through a mounting hole formed in the board, and is connected to a conductive material provided on the other surface of the board by soldering. In addition, the bus bar is fixed to the board, and the terminals of the electronic device are inserted into through holes formed in communication with the bus bar and the board, and soldered to the bus bar for connection. 3. The electronic circuit unit according to any one of 3 above. 5. The electronic circuit unit is built in an electric connection box such as a junction box in which busbars are stacked and arranged in a case, and a conductive material of an electronic circuit is connected to the busbar arranged in the case. The electronic circuit unit according to any one of claims 1 to 4.