JP4651477B2 - Circuit board - Google Patents

Description

  The present invention relates to a circuit board having electronic components mounted on a board body.

  As a circuit board, for example, there is a circuit board that is used by being incorporated in a battery pack for a mobile phone and includes a protection circuit for preventing overdischarge or overcharge of a rechargeable battery built in the battery pack (for example, a patent). Reference 1).

  FIG. 5 shows an example of such a circuit board. The circuit board B includes a plurality of electronic components 92 constituting a protection circuit, and a board body 91 on which these electronic components 92 are mounted. The substrate body 91 is formed of an insulator such as glass epoxy resin, and has a long rectangular shape corresponding to the shape of the battery pack (not shown). The plurality of electronic components 92 are mounted on the substrate main body 91 using, for example, a solder reflow technique, and a pair of metals for connecting a rechargeable battery via a wiring pattern (not shown) formed on the substrate main body 91. The plate 93 is electrically connected.

JP 2002-135000 A (FIG. 9)

  However, in such a circuit board B, for example, when incorporated in a battery pack, there is a case where the bending force M is applied to bend the circuit board B in the thickness direction of the board body 91. When the substrate body 91 receives the bending force M, bending deformation occurs. In particular, when the substrate body 91 is made of resin, the bending deformation is also increased. Furthermore, since the substrate main body 91 has a long rectangular shape, a large bending stress is easily generated in a portion near the center of the substrate main body 91, resulting in a large distortion. When such distortion occurs, a large stress acts on a soldering portion that is a joint portion between the plurality of electronic components 92 and the substrate body 91, and the electronic component 92 may be peeled off from the substrate body 1 in some cases. When this occurs, the electronic component 92 is prevented from conducting properly, and the protection circuit configured by the circuit board B may not function properly.

  The present invention has been conceived under the circumstances described above, and provides a circuit board capable of suppressing separation of an electronic component from the substrate body even when bending deformation occurs in the substrate body. Is an issue.

  In order to solve the above problems, the present invention takes the following technical means.

A circuit board provided by the present invention is a circuit board provided with a board body and a plurality of electronic components mounted on the board body. The board body has a long rectangular shape and a longitudinal direction. Has a metal plate for electrical connection on both sides and is formed of glass epoxy resin, and a groove is formed in the short direction only on one side opposite to the mounting surface on which the plurality of electronic components are mounted is the cross-sectional area by which are small bending deformation easier portion than the peripheral portion is provided so as to cross the lateral direction of the board body, said plurality of electronic components, avoiding the bending deformation easily unit And the plurality of electronic components are a pair of first electronic components having external leads for mounting, a chip shape of a long rectangular shape, and spaced apart in the longitudinal direction. For surface mounting Includes a plurality of second electronic component having the electrode, the plurality of first electronic components together are disposed separately in the longitudinal direction of the substrate by sandwiching the bending deformation easily unit, are each While the external leads are mounted in a posture facing the longitudinal direction of the substrate body, the plurality of second electronic components are mounted in a posture in which the longitudinal direction faces the short direction of the substrate body . Any one of them is arranged between all of the plurality of first electronic components and the bending deformable portion .

According to such a configuration, the bending deformation easy portion has a smaller section modulus with respect to the bending moment than its peripheral portion. For this reason, when bending deformation occurs in the entire substrate body, compared to the prior art, the bending deformation easy portion is greatly distorted, whereas the bending in which the electronic component is mounted is performed. Distortion that occurs in a portion other than the easily deformable portion can be reduced. Therefore, since the stress acting on the joint portion for mounting the electronic component on the substrate body is reduced, the possibility that the electronic component is peeled off from the substrate body is reduced. Can function normally. Further, when the package component is mounted on the long rectangular substrate body, the external lead of the package component is directed in the longitudinal direction of the substrate main body in order to increase the space efficiency in the long rectangular substrate body. Is advantageous. On the other hand, it is necessary to prevent stress from being generated in the solder part connecting the external lead due to the moment in the longitudinal direction of the substrate body. However, since deformation concentrates on the easily deformable part, the external lead It is possible to reduce the stress of the solder portion connecting the two. Therefore, it is suitable for preventing the peeling of the package component. Furthermore, the discrete parts often have a main body formed of ceramics or the like, and have a high risk of being cracked or damaged by an external force. In this regard, the discrete component has a posture in which the longitudinal direction thereof faces the short direction of the substrate body, and the discrete component itself is not easily subjected to a moment in relation to the longitudinal direction of the substrate body. Yes. As a result, even if an excessive moment that cannot be absorbed by the bending-deformable portion or a momentary impact force is applied, no excessive moment is generated in the discrete component. Therefore, it is suitable for protecting the discrete component. Further, unlike the embodiment in which the notch portion is formed in the side surface portion of the substrate body, the side surface portion can be made smooth, so that the electronic body can be made without reducing the area of the substrate body. Suppression of part peeling can be achieved. The surface on which the electronic component is mounted is a smooth surface that does not have the groove. Therefore, for example, when a wiring pattern that is electrically connected to the electronic component is formed on the surface, the formation becomes easy.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the drawings.

FIG. 1 shows an example of a circuit board as a reference example . The circuit board A1 of this reference example is mounted on a battery pack (not shown) used in a mobile phone, and is for preventing overdischarge and overcharge of a rechargeable battery (not shown) built in the battery pack. is there. The circuit board A1 includes a board body 1, a plurality of electronic components 2, and a pair of metal pieces 3.

  The substrate body 1 is made of glass epoxy resin, and has a rectangular shape in plan view in order to cope with the thinning of the battery pack accompanying the downsizing of the mobile phone. A cutout portion 11 a having a semicircular shape in plan view is formed near the center in the longitudinal direction of the substrate body 1. By forming this notch portion 11a, the central portion in the longitudinal direction of the substrate body 1 is a bending deformation easy portion 1A having a smaller width and cross-sectional area than the peripheral portion.

The plurality of electronic components 2 are for constituting a protection circuit for protecting the battery pack. The plurality of electronic components 2 are mounted by soldering, for example, using a solder reflow technique on a portion of the board body 1 that avoids the bending deformation easy portion 1A. More of electrical components 2, bending deformation easily unit 1A that is closer to electronic components 2a, 2b, such that the bending deformation easily unit 1A is positioned at these substantially intermediate, substantially equal distance from the bending deformation easily portion 1A Implemented separately. The electronic component 2 includes a first electronic component 2c and a second electronic component 2d. The first electronic component 2 c has an external lead for mounting, and the external lead is mounted in a posture facing the longitudinal direction of the board body 1. The second electronic component 2d is a relatively small component made of salamic or the like and does not have an external lead. The second electronic component 2d is mounted with a posture in which the longitudinal direction thereof faces the short direction of the upper substrate body 1.

  The pair of metal pieces 3 is for connecting the circuit board A1 and the rechargeable battery, and has a long rectangular Ni plate shape. These metal pieces 3 are provided at both end portions of the substrate body 1 and are used as terminal plates that are electrically connected to the rechargeable battery, for example, by bending a predetermined portion. Further, the pair of metal pieces 3 and the plurality of electronic components 2 are electrically connected to each other by a wiring pattern (not shown) formed on the substrate body 1.

According to this reference example , when the circuit board A1 is incorporated into the battery pack, for example, when the board body 1 receives a force M that causes the board body 1 to bend in the thickness direction, the bending-deformable part 1A is compared with its peripheral part. Since the section modulus with respect to the bending moment is small, a strain larger than that in the peripheral portion is generated, and the strain generated in the peripheral portion is reduced. Since the plurality of electronic components 2 are all mounted so as to avoid the bendable deformation portion 1A, the distortion generated in the portion of the substrate body 1 where these electronic components 2 are joined is small. Therefore, the stress generated in the soldering portion for mounting the plurality of electronic components 2 is reduced, and the plurality of electronic components 2 are difficult to peel from the board body 1. Thereby, it becomes possible to suppress the conduction between the plurality of electronic components 2 and the wiring pattern, and the function as the protection circuit can be normally exhibited.

Electronic components 2a, 2b, the distance from the bending deformation easily unit 1A is mounted to be substantially equal to each other. Prevention Therefore, the substrate main body 1 sac Chi electronic components 2a, portions each joined and 2b, without that strain occurring in one becomes unreasonably larger than the strain occurring in the other, the release for both parts It is suitable for doing.

  The notch portion 11a can be easily formed, for example, in the process of adjusting the outer shape of the substrate body 1 when the substrate body 1 is manufactured, and there is little possibility of reducing the work efficiency in manufacturing the substrate body 1. The cutout portion 11a can also be used as a positioning recess when the circuit board A1 is incorporated into the battery pack.

When the first electronic component 2 c is mounted on the long rectangular substrate body 1, the external body lead of the first electronic component 2 c is oriented in the longitudinal direction of the substrate main body 1. This is advantageous in increasing the space efficiency. On the other hand, although it is necessary to prevent stress from being generated in the solder portion connecting the external lead due to the moment in the longitudinal direction of the substrate body 1, deformation concentrates on the bending deformable portion 1A. It is possible to reduce the stress of the solder portion connecting the two. Therefore, it is suitable for preventing peeling of the first electronic component 2c. Furthermore, the second electronic component 2d often has a main body formed of ceramics or the like, and is likely to be cracked or damaged by an external force. In this regard, the second electronic component 2d has a posture in which the longitudinal direction thereof faces the short direction of the substrate body 1, and the second electronic component 2d itself has a moment in relation to the longitudinal direction of the substrate body 1. The posture is difficult to receive. Thereby, even if an excessive moment that cannot be absorbed by the bending deformation easy portion 1A or an instantaneous impact force is applied, an excessive moment is not generated in the second electronic component 2d. Therefore, it is suitable for protecting the second electronic component 2d.

2-4 shows an example of a circuit board according to another example and the present invention of the circuit board as a reference example. In FIG. 2 and subsequent figures, the Reference Example and the same or similar elements are denoted with the same reference numerals as the reference example, it will not be further described.

  In the circuit board A <b> 2 shown in FIG. 2, a hole 11 b is formed near the center in the longitudinal direction of the board body 1. The hole 11b has an elliptical shape that is long in the width direction in plan view. By forming the hole 11b, the central portion of the substrate body 1 is a bending deformation easy portion 1A having a smaller cross-sectional area than the peripheral portion. The plurality of electronic components 2 are mounted on the board body 1 avoiding the bending deformation easy portion 1A, as in the above embodiment.

Also according to this reference example, by generating large distortion than the peripheral portion on the bending deformation facilitating portion 1A, to reduce the strain occurring in the portion where a plurality of electronic components 2 are mounted, a plurality of electronic components 2 are substrate main body 1 It can suppress peeling from. Moreover, the hole 1b is formed in a non-notch shape. Therefore, unlike the case where the notch-shaped recess is formed on the side surface extending in the longitudinal direction of the substrate body 1, the side surface can be made a smooth surface.

  In the circuit board A <b> 3 shown in FIG. 3, a groove 11 c is formed on the lower surface of the board body 1. By forming the groove 11c, the central portion in the longitudinal direction of the substrate body 1 is a bending deformation easy portion 1A having a small thickness and a small cross-sectional area.

  According to such an embodiment, since the groove portion 11c is provided on the lower surface of the substrate body 1, the upper surface of the substrate body 1 on which the plurality of electronic components 2 are mounted has a smooth surface having no recess. Become. For this reason, for example, when a wiring pattern that conducts to a plurality of electronic components 2 is formed on the upper surface of the substrate body 1, it is not necessary to form the wiring pattern in a complicated shape along the groove portion, and it can be easily formed. it can. In addition, compared with the case where notches and holes are provided in the substrate body 1, the area of the upper surface can be increased, so that the pitch of the wiring pattern extending in the longitudinal direction of the substrate body 1 can be increased.

  The circuit component A4 shown in FIG. 4 is provided with three bending deformable portions 1Aa to 1Ac. The bending deformation easy portion 1Aa is provided in the left portion of the substrate body 1 by forming four small holes 11d. The bending-deformable part 1Ab is provided by forming two notches 11e in the central part of the substrate body 1 in the longitudinal direction. Further, the bending-deformable part 1Ac is provided in the right part of the substrate body 1 by forming a notch part 11f and a groove part 11g in a composite manner. The plurality of electronic components 2 are mounted on the board body 1 so as to avoid these bending-deformable portions 1Aa to 1Ac.

According to such a reference example , when a bending force is applied to the substrate body 1, a greater strain than the peripheral portion is generated in each of the bending deformable portions 1 </ b> Aa to 1 </ b> Ac. Therefore, it is possible to suppress peeling of the electronic component 2 even when a larger bending deformation occurs in the substrate body 1 as compared with the configuration in which only one bending deformation easy portion is provided. In addition, compared to a configuration in which only one bending deformable portion is provided, it is possible to reduce the magnitude of distortion generated in the bending deformable portions 1Aa to 1Ac, and to improve the durability of the circuit board A4. You can also plan.

  The specific configuration of the circuit board according to the present invention is not limited to the above-described embodiment, and various design changes can be made.

  The application of the circuit board according to the present invention is not limited to the above embodiment. Therefore, the electronic component may constitute a circuit other than the protection circuit of the battery pack, and its type and function are not limited.

It is a whole perspective view of an example of a circuit board as a reference example . It is a whole perspective view of the other example of the circuit board as a reference example . 1 is an overall perspective view of an example of a circuit board according to the present invention. It is a whole perspective view of the other example of the circuit board as a reference example . It is a whole perspective view which shows an example of the conventional circuit board.

A1 to A4 Circuit board 1 Substrate body 1A, 1Aa to 1Ac Bendable deformation part 2 Electronic part 2c First electronic part 2d Second electronic part 3 Metal plates 11a, 11e, 11f Notch part 11b, 11d Hole part 11c, 11g groove

Claims (1)

A substrate body;
A plurality of electronic components mounted on the board body;
A circuit board comprising:
The board body has a long rectangular shape, has metal plates for electrical connection on both sides in the longitudinal direction, is formed of glass epoxy resin , and has a mounting surface on which the plurality of electronic components are mounted. The easy-to-bend deformable part whose cross-sectional area is smaller than the peripheral part is formed so as to cross the short direction of the substrate body by forming the groove part in the short direction only on one side opposite to
The plurality of electronic components are mounted at positions avoiding the bending deformation easy portion, and
The plurality of electronic components include a plurality of first electronic components having external leads for mounting, and a plurality of second electronic components having a pair of surface mounting electrodes which are formed in a long rectangular chip shape and spaced apart in the longitudinal direction . Electronic components and
The plurality of first electronic components are separately arranged in the longitudinal direction of the substrate with the bending deformable portion interposed therebetween, and each of the first electronic components is mounted in a posture in which the external leads face the longitudinal direction of the substrate body. While
The plurality of second electronic components are mounted in a posture in which the longitudinal direction thereof faces the short direction of the substrate body , and any one of them is easily bent and deformed with all of the plurality of first electronic components. A circuit board, wherein the circuit board is disposed between the circuit board and the circuit board .

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