JP2010080574A - Joining structure and joining method of bus bar - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solder an end part of a bus bar firmly to a joint portion of a circuit board without causing whiskers. <P>SOLUTION: Bus bars 3 are arranged, being spaced apart from each other, on a circuit board 1. An end part of the individual bus bars 3 is bend into a joint 32 which can be brought into surface contact with a joint portion 2 of the circuit board 1. At the bending portion A, a reinforcing portion 33 is integrally formed to keep constant a bending angle between the joint 32 and a proximal end (leg portion 31) of the bus bar 3, allowing the joint 32 to be soldered in contact with the joint portion 2. It is preferred that the edge of the leading end of the joint 32 is non-angular. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a structure for joining bus bars arranged on a circuit board at intervals to the circuit board, and a joining method thereof.

  For example, in an electro-hydraulic unit provided in an electro-hydraulic power steering, a control unit housing is provided between facing portions of an electric motor and an oil pump, and a drive for controlling the driving of the electric motor is provided inside the control unit housing. A circuit board for a circuit or a control circuit is provided, and a bus bar that forms a power supply line from the battery to the electric motor is provided in a state of being supported by an insulating support frame at a distance from the circuit board. (See Patent Document 1).

As described above, in the case where the bus bars are arranged on the circuit board at intervals, when connecting the bus bar to a required part of the circuit board, the end of the bus bar is inserted into the through hole of the circuit board. In addition to connecting, a leg that extends to the circuit board side is formed at the end of the bus bar, and the tip of the leg is bent to form a joint. Soldering is performed in a state of being in surface contact with the solder. This is because the contact area between the joint and the part to be joined is increased, the joint strength is increased, and the heat generated by the large current in the bus bar is radiated to the circuit board side (Patent Document). 2).
JP-A-11-334616 JP 2007-124862 A

  By the way, when the joint portion is formed by bending the leg portion of the bus bar and the joint portion is soldered to the joined portion, it is desirable that the joined portion is in full surface contact with the joined portion. In the joint formed by bending, it is difficult to make an exact right angle with respect to the leg due to the spring back, and when the bending angle between the joint and the leg is less than 90 degrees, the joint is covered. When it is brought into contact with the joint part, there is a problem that the tip of the joint part is in a floating state and a gap is formed between the joint part and solid soldering cannot be performed.

  Therefore, conventionally, as shown in FIG. 4, the joint portion 22 is bent at an obtuse angle slightly larger than 90 degrees with respect to the leg portion 21. The bus bar 20 is pressed against the circuit board 23 so that the joining portion 22 comes into surface contact with the joined portion 24 and soldered in that state.

  However, in the above method, the force applied to the bus bar 20 does not always effectively act on the joint portion 22 due to the flexibility of each part of the bus bar 20, and a gap remains between the joint portion 22 and the joined portion 24. As a result, soldering may not be possible.

  Further, at the soldering portion, internal stress is generated at the bent portion between the leg portion 21 and the joint portion 22 or the like. This internal stress is not preferable in so-called lead-free soldering that does not contain lead, because it promotes the generation of whiskers.

  In view of the above-described problems in the soldering locations of the bus bar joints, the present invention makes it possible to perform soldering firmly by surface contact, reduce stress concentration, and cause problems such as whisker generation. The challenge is to avoid it.

  A first aspect of the present invention is a structure in which bus bars arranged at intervals on a circuit board are joined to soldered parts of the circuit board by soldering. On the other hand, a joint that can be brought into surface contact is formed by bending, and a reinforcing portion that holds the bending angle between the joint and the base end side at a fixed angle is integrally formed at the bent portion. And the solder is soldered in a state where the joint is in surface contact with the part to be joined.

  A second aspect of the present invention is a method of joining a bus bar disposed on a circuit board with a gap to a portion to be joined of the circuit board by soldering. A joining portion that can be brought into surface contact with the joined portion is formed by bending, and a reinforcing portion that holds a bending angle between the joining portion and a portion closer to the base end side at a certain angle is provided at the bent portion. It is formed, the joining portion is brought into contact with the joined portion in a posture parallel to the joined portion, and soldering is performed in a state where the joining portion is in surface contact with the joined portion. To do.

  According to the above configuration, in the bus bar, the bending angle between the joint portion and the portion closer to the base end side is kept constant by the reinforcing portion. Therefore, the joining portion can be brought close to and brought into contact with the joined portion while maintaining a posture parallel to the joined portion, and the entire surface of the joining portion can be brought into surface contact with the joined portion by making such contact. Can do. Therefore, soldering can be performed in a state where there is no gap between the joint portion and the joint portion, and a large joint strength can be obtained.

  Further, in this case, unlike the conventional case, it is not necessary to strongly press the bonding portion against the bonded portion, so that almost no internal stress is generated, and thus whisker generation can be suppressed or prevented.

  In the above configuration, the reinforcing portion is formed by bending the left and right side edge portions in the width direction of the bent portion inside the bent portion into a triangular swash plate shape, and in the width direction of the bent portion. It is desirable to be provided on both sides. Moreover, it is desirable that the front end edge of the joint portion has a cornerless shape.

  Even now, if the shape of the contact surface between the joint and the part to be joined is 90 degrees or a shape having an acute corner, the internal stress may concentrate on the corner. As described above, if there are reinforcing parts on both sides in the width direction of the bent part, the shape of the contact surface between the joined part and the joined part becomes a shape with a right-angled corner on the bent part side, and internal stress Is less likely to concentrate, and whisker generation is suppressed or prevented.

  Further, as described above, when the tip end edge of the joint portion has a shape with no corners, no internal stress is concentrated on the tip end side of the joint portion, and the generation of whiskers is suppressed or prevented.

  According to the present invention, strong soldering can be achieved by full surface contact between the joint portion and the joined portion, and the concentration of internal stress at the soldering location is alleviated, and whisker generation is suppressed or prevented. Can do.

  Hereinafter, the best mode of the present invention will be described with reference to FIG. 1 and FIG. FIG. 1 is a perspective view of a bus bar joint structure according to an embodiment of the present invention, and FIG. 2 is a side view of the bus bar joint structure, both showing a state before soldering.

  In FIGS. 1 and 2, reference numeral 1 is a circuit board, 2 is a conductor pattern as a bonded portion on the circuit board 1, 3 is a bus bar, and 4 is an insulating support frame that supports the bus bar 3.

  On the circuit board 1, bus bars 3 are arranged in a state of being supported by a support frame 4 at intervals.

  The end of the bus bar 3 protruding from the support frame 4 is formed with a leg 31 that extends toward the circuit board 1, and the tip of the leg 31 is inclined at a predetermined angle with respect to the leg 31 ( By bending (90 degrees in the illustrated example), two joint portions 32 are formed on the conductor pattern of the circuit board 1.

  A reinforcing portion 33 is provided at a bent portion A of the joint portion 32 with respect to the leg portion 31. The reinforcing portion 33 is for maintaining a bending angle between the joint portion 32 and the leg portion 31 which is a portion closer to the base end side at a constant angle (specifically, 90 degrees). In the present embodiment, the reinforcing portion 33 bends the side edge portions on the left and right sides in the width direction of the bent portion A to the inside of the bent portion A so that the portion closer to the side edge is more inside, thereby forming a triangular swash plate shape. And are provided on both sides in the width direction of the bent portion A, respectively.

  Moreover, the width direction right and left both sides of the front-end | tip edge of the junction part 32 are formed in circular arc shape so that it may not have a corner | angular. In FIG. 1, reference numeral 32 a indicates an arc-shaped portion at the tip of the joint portion 32.

  The bus bar 3 is configured as described above. Next, with reference to FIG. 2, a method of joining the joining portion 32 of the bus bar 3 to the conductor pattern 2 of the circuit board 1 will be described.

  At the time of soldering, the bus bar 3 is moved to the circuit board 1 side while keeping the joint portion 32 in parallel with the conductor pattern 2, thereby bringing the joint portion 32 close to and in contact with the conductor pattern 2. In this case, in the bus bar 3, the bending angle between the joint portion 32 and the leg portion 31 is kept constant by the reinforcing portion 33, and the bending angle does not change due to a springback or the like. By adjusting the posture of the bus bar 3 with respect to 1, the joint portion 32 can be made parallel to the conductor pattern 2.

  The joint portion 32 is in contact with the conductor pattern 2 while maintaining a posture parallel to the conductor pattern 2, so that the joint portion 32 and the conductor pattern 2 are in surface contact with each other. Then, by performing half-attachment in this state, the joint portion 32 is firmly soldered to the conductor pattern 2 with no gap.

  In this case, unlike the conventional joining method, no force is applied to change the bending angle of the joint portion 32 with respect to the leg portion 31, and therefore, almost no internal stress is generated at the soldering point. At the soldering point, the contact surface B between the joint portion 32 and the conductor pattern has a shape that does not have 90 degrees or acute corners, as clearly shown in FIG. That is, on the side of the bent portion A, a right-angled corner is formed for the reinforcing portion 33, and on the tip side of the joint portion 32, the arc-shaped portion 32a has no corner. . Thus, since the contact surface B between the joint portion 32 and the conductor pattern 2 has a shape that does not have a sharp corner, there is no portion where the internal stress is concentrated, thereby suppressing or preventing the occurrence of whiskers. Is done.

  In FIGS. 1 and 2, as the reinforcing portion 33, the left and right side edge portions in the width direction of the bent portion A are formed in a triangular swash plate shape. As long as the bending angle between the base end portion (the leg portion 31) and the base end portion can be maintained at a constant angle, the shape is not limited to the above-described shape, and for example, a shape as shown in FIG. .

  FIG. 3 is a perspective view of a bus bar according to another embodiment of the present invention. In this embodiment, in the bent portion A between the leg portion 31 and the joint portion 32 of the bus bar 3, the intermediate portion in the width direction is An oblique rib-shaped reinforcing portion 34 is formed by being pushed in from the outside of the bent portion A and raised inside.

In the perspective view of the joining structure of the bus-bar which concerns on embodiment of this invention, the state before soldering is shown. The side view of the bus bar joining structure shows a state before soldering. The perspective view of the bus-bar of other embodiment of this invention. The side view of the conventional bus bar joining structure shows a state before soldering.

Explanation of symbols

1 Circuit board 2 Conductor pattern (bonded part)
3 Bus bar 31 Leg 32 Joint part 33 Reinforcement part 4 Support frame A Bending part B Contact surface

Claims (4)

A structure in which bus bars arranged at intervals on a circuit board are joined to soldered parts of the circuit board by soldering,
At the end portion of the bus bar, a joint portion that can be brought into surface contact with the joined portion is formed by bending, and a bending angle between the joint portion and a portion closer to the proximal end is formed at the bent portion. The bus bar joining structure is characterized in that a reinforcing portion for holding the joint at a constant angle is integrally formed, and the joining portion is soldered in a state of surface contact with the joined portion. In the joined structure of the bus bar according to claim 1,
The reinforcing portion is formed by bending the left and right side edge portions in the width direction of the bent portion inside the bent portion into a triangular swash plate shape, and is provided on both sides in the width direction of the bent portion. A bus bar joint structure characterized by that. In the junction structure of the bus bar according to claim 1 or 2,
The bus bar joining structure, wherein the leading edge of the joining part has a cornerless shape. A method of joining bus bars arranged at intervals on a circuit board to soldered parts of the circuit board by soldering,
At the end portion of the bus bar, a joint portion that can be brought into surface contact with the joined portion is formed by bending in advance, and a bending angle between the joint portion and a base end side portion is formed at the bent portion. Form a reinforcing part to hold at a certain angle,
A joining method of a bus bar, wherein the joining portion is brought into contact with the joined portion in a posture parallel to the joined portion, and soldering is performed in a state where the joining portion is in surface contact with the joined portion. .

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