JP6028762B2 - Circuit assembly and electrical junction box - Google Patents

Description

  The present invention relates to a circuit structure and an electrical junction box.

  2. Description of the Related Art Conventionally, a circuit structure including various electronic components, an electronic component, a circuit board, and a bus bar superimposed on the circuit board is known (see, for example, Patent Document 1). In such a circuit structure, various electronic components are connected by a method such as soldering.

JP 2013-99071 A

  Examples of the electronic component connected to the circuit structure include a relay and a shunt resistor. Among such electronic components, the shunt resistor is entirely made of a metal material. Therefore, when soldered to the bus bar, the solder 133 may spread and reach the resistance portion 132 as shown in FIG. . In such a case, there is a problem in that the solder connection shape is not appropriate, so that a solder crack is developed due to the thermal shock of the thermal cycle, and the electrical connection reliability is lowered.

  An object of this invention is to improve electrical connection reliability in a circuit structure provided with a shunt resistor.

  The present invention includes a substrate having an opening, a bus bar overlaid on one surface of the substrate, a connection terminal portion connected to the bus bar by soldering in the opening of the substrate, and a connection terminal portion. A shunt resistor having a resistance portion, and a solder fillet that connects the shunt resistor and the bus bar is formed closer to the connection terminal portion than the resistance portion.

  Moreover, this invention is an electrical junction box provided with the said circuit structure and the case which accommodates a circuit structure.

In the present invention, the solder fillet connecting the shunt resistor and the bus bar is formed closer to the terminal portion than the resistance portion of the shunt resistor, so that the designed resistance value can be obtained.
By the way, as shown in FIG. 6, when the solder 133 reaches the resistance part 132 of the shunt resistor and spreads and fills the space between the resistance part 132 and the bus bar 120, it is caused by the thermal shock of the thermal cycle. There is a concern that solder cracks are likely to occur. However, according to the present invention, since the solder fillet for connecting the shunt resistor and the bus bar is formed closer to the terminal portion than the resistance portion of the shunt resistor, the solder that fills the space between the resistance portion and the bus bar. Is difficult to form, and even when subjected to a thermal shock of a cooling and heating cycle, solder cracks are less likely to occur and electrical connection reliability is improved.

The present invention may have the following configuration.
A notch portion may be provided in a portion of the bus bar that overlaps the resistance portion of the shunt resistor, and an end portion of the notch portion may be set closer to the connection terminal portion than the resistance portion.
With such a configuration, the bus bar is cut out to a position near the connection terminal portion of the shunt resistor, so that it is possible to reliably suppress the solder from spreading to the resistance portion.

  ADVANTAGE OF THE INVENTION According to this invention, in a circuit structure provided with a shunt resistor, electrical connection reliability can be improved.

The top view of the electrical junction box of Embodiment 1 Top view of the circuit board before connecting the shunt resistor Disassembled perspective view of circuit structure The principal part enlarged plan view which shows the state which connected the shunt resistor to the bus bar Partial sectional view taken along line AA of FIG. Partial sectional view of a conventional circuit structure

<Embodiment 1>
An electrical junction box 10 including a circuit structure 11 according to Embodiment 1 will be described with reference to FIGS.
The electrical connection box 10 of this embodiment includes a circuit board 13 (an example of a board), a circuit structure 11 including a bus bar 20, and a case 12 made of a synthetic resin that houses the circuit structure 11. In the following description, the upper side in FIG. 5 is described as the front side or the upper side, and the lower side is described as the back side or the lower side.

  As shown in FIGS. 1 and 3, the circuit structure 11 includes a circuit board 13, a shunt resistor 30 disposed on the surface of the circuit board 13 (upper surface in FIG. 3), and the back surface of the circuit board 13 (FIG. 3). And a plurality of bus bars 20 bonded to the lower surface) via an adhesive sheet 15.

(Circuit board 13)
The circuit board 13 is substantially L-shaped when viewed from above, and a conductive path (not shown) is formed on the surface thereof by a printed wiring technique.

  An opening 14 for connecting the two shunt resistors 30 to the bus bar 20 is formed at a position on the circuit board 13 where the shunt resistors 30 are arranged. As shown in FIG. 4, the opening 14 opens in a rectangular shape, and is arranged with a gap S <b> 1 between the two shunt resistors 30 and the opening edge. .

(Adhesive sheet 15)
The adhesive sheet 15 is made of an insulating material and is substantially the same shape and size as the circuit board 13. As shown in FIG. 4, the adhesive sheet 15 is provided with a sheet opening 16 that is slightly larger than the opening 14 of the circuit board 13 at a position corresponding to the opening 14 of the circuit board 13.

(Bus bar 20)
The plurality of bus bars 20 are formed by pressing a metal plate into a predetermined shape. The bus bars 20 are routed in a predetermined pattern between the adjacent bus bars 20 via a gap S2. Among the plurality of bus bars 20, some of the bus bars 20 are provided with bolt insertion holes 21 through which bolts are inserted, and are connected to an external power source via the bolts.

  Of the plurality of bus bars 20, the bus bar 20 to which the shunt resistor 30 is connected is notched corresponding to the resistance portion 32 of the shunt resistor 30 (hereinafter referred to as “notch portion 22”). As shown in FIG. 4, the notch 22 is provided by notching the two bus bars 20 in a rectangular shape. The notch 22 is connected to the gap S <b> 2 between the two bus bars 20.

  As shown in FIG. 5, the end 22A of the notch 22 formed in the bus bar 20 to which the shunt resistor 30 is connected is set closer to the connection terminal 31 than the resistor 32 of the shunt resistor 30. The notch 22 is provided over the entire area overlapping the resistor 32.

(Shunt resistor 30)
The shunt resistor 30 is disposed in the opening 14 of the circuit board 13 and connected to the bus bar 20 by soldering. In the present embodiment, two shunt resistors 30 are arranged for each opening 14 of the circuit board 13.

  The shunt resistor 30 has a connection terminal portion 31 connected to the bus bar 20 and a resistance portion 32 connected to the connection terminal portion 31. As shown in FIG. 5, the resistance portion 32 of the shunt resistor 30 is provided on a flat surface protruding upward. The resistance portion 32 is provided in a region R between two dotted lines in FIG. Connection terminal portions 31 are connected to both ends of the resistance portion 32 of the shunt resistor 30, respectively.

  In this embodiment, the solder fillet 33 that connects the shunt resistor 30 and the bus bar 20 is formed closer to the connection terminal portion 31 than the resistance portion 32 of the shunt resistor 30.

(Method for manufacturing electrical junction box 10)
Next, an example of the manufacturing method of the electrical junction box 10 according to the present embodiment will be described.
The adhesive sheet 15 cut into a predetermined shape is superposed on the lower surface of the circuit board 13 having a conductive path formed on the surface by a printed wiring technique, and a plurality of bus bars 20 are pressed in a state where they are arranged at predetermined positions. Thereby, the circuit board 13 and the plurality of bus bars 20 are bonded and fixed to each other via the adhesive sheet 15, and a part of the bus bar 20 includes the opening 14 and the adhesive sheet of the circuit board 13 as shown in FIG. 2. The exposed state is through the 15 sheet openings 16.

  Next, solder is applied to a predetermined position of the circuit board 13, and two shunt resistors 30 are placed on the bus bar 20 exposed from the opening 14 of the circuit board 13, and placed in a reflow furnace for soldering. As a result, the circuit structure 11 is obtained. In this circuit structure 11, the solder fillet 33 that connects the shunt resistor 30 and the bus bar 20 is formed closer to the connection terminal portion 31 than the resistance portion 32, as shown in FIG.

  When the circuit structure 11 obtained in this way is accommodated in the case 12, the electrical junction box 10 of this embodiment is obtained.

(Operational effect of this embodiment)
Hereinafter, the effect of this embodiment is demonstrated.
As in the conventional example shown in FIG. 6, the solder 133 connecting the shunt resistor 130 and the bus bar 120 reaches not only the connection terminal portion 131 but also the resistance portion 132 and spreads to fill the space between the resistance portion 132 and the bus bar 120. If formed in this manner, solder cracks are likely to occur due to the thermal shock of the thermal cycle due to the inappropriate shape of the solder part. In FIG. 6, 111 is a circuit structure, 113 is a circuit board, 114 is an opening 14 of the circuit board, 115 is an adhesive sheet for connecting the circuit board and the bus bar, and 116 is a sheet opening 16.

On the other hand, in this embodiment, the solder fillet 33 that connects the shunt resistor 30 and the bus bar 20 is formed in an appropriate shape at a position closer to the terminal portion than the resistance portion of the shunt resistor 30.
Therefore, according to this embodiment, the designed resistance value is obtained. In addition, according to the present embodiment, the solder fillet connecting the shunt resistor 30 and the bus bar 20 is difficult to form a solder that fills the resistor portion 32 of the shunt resistor and the bus bar 20. Even if it is received, solder cracks are less likely to occur and electrical connection reliability is improved.

  In addition, according to the present embodiment, the notch 22 is provided in the entire region of the bus bar 20 that overlaps the resistor 32 of the shunt resistor 30, and the end 22 </ b> A of the notch 22 is connected to the connecting terminal portion than the resistor 32. Since it is set close to 31, the bus bar 20 is cut out to a position near the connection terminal portion 31 of the shunt resistor 30, and solder can be reliably suppressed from spreading to the resistance portion 32.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.
(1) In the said embodiment, although the circuit structure 11 without a heat sink was shown, you may equip the surface on the opposite side to the circuit board side of the bus bar 20 with the heat sink.
(2) In the above embodiment, the notch 22 is provided in the entire area of the bus bar 20 that overlaps the resistor 32 of the shunt resistor 30, and the end 22 </ b> A of the notch 22 is closer to the connection terminal 31 than the resistor 32. Although the example set to is shown, it is not limited to this. A part of the bus bar may remain in the portion overlapping the resistance portion of the shunt resistor.
(3) In the above embodiment, two shunt resistors 30 are provided. However, the present invention is not limited to this, and one or three or more shunt resistors 30 may be provided.

DESCRIPTION OF SYMBOLS 10 ... Electrical junction box 11 ... Circuit structure 12 ... Case 13 ... Circuit board (board | substrate)
DESCRIPTION OF SYMBOLS 14 ... Opening part 15 ... Adhesive sheet 16 ... Sheet opening part 20 ... Bus bar 22 ... Notch part 22A ... End part 30 ... Shunt resistor 31 ... Connection terminal part 32 ... Resistance part 33 ... Solder fillet

Claims (3)

A substrate having an opening;
A bus bar overlaid on one side of the substrate;
A connection terminal portion connected to the bus bar by soldering in the opening of the substrate, and a shunt resistor having a resistance portion continuous from the connection terminal portion,
A circuit structure in which a solder fillet for connecting the shunt resistor and the bus bar is formed closer to the connection terminal portion than the resistance portion. The notch part is provided in the part which overlaps with the said resistance part of the said shunt resistor of the said bus bar, The edge part of the said notch part is set near the said connection terminal part rather than the said resistance part. Circuit construct. An electrical junction box comprising: the circuit structure according to claim 1; and a case for housing the circuit structure.

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