JP2013165233A - Printed wiring board and electronic substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a short circuit between a signal pattern and the like and a ground pattern even when a three-terminal capacitor spins round at the time of installation.SOLUTION: In a printed wiring board 2 on which four pads 2a1, 2b1 to which terminals of a surface-mountable three-terminal capacitor 3 are connected are arranged in a cross shape, at least either pair of pads 2a1, 2b1 has plan view shapes such that corners 2a2 close to the neighboring pads are cut off.

Description

  The present invention relates to a printed wiring board and an electronic board.

  As shown in Patent Document 1, as a conventional electronic component for removing high-frequency noise that has entered a signal pattern or a power supply pattern (hereinafter referred to as a signal pattern or the like), A surface-mount type three-terminal capacitor having a ground terminal provided therebetween is used. Some three-terminal capacitors have a ground terminal separated into two.

  A printed wiring board on which such a three-terminal capacitor is mounted is provided with four pads according to the terminals of the three-terminal capacitor. Of these four pads, two are provided in the signal pattern and the other two are provided in the ground pattern. These four pads are arranged in a cross so that two provided on the signal pattern or the like face each other and two provided on the ground pattern face each other.

Japanese Patent Laid-Open No. 2001-15585

  By the way, the surface mount type three-terminal capacitor is mounted on a printed wiring board by so-called reflow soldering. At this time, the placement position of the three-terminal capacitor may be shifted from the correct position in the rotational direction due to an attachment error or the flow of molten solder. If the three-terminal capacitor rotates from its original position in this way, the terminal (input / output terminal or ground terminal) of the three-terminal capacitor bridges to the two pads, and the signal pattern and the ground pattern are short-circuited. End up.

  The present invention has been made in view of the above-described problems, and an object thereof is to prevent a signal pattern or the like and a ground pattern from being short-circuited even when a three-terminal capacitor rotates during mounting. To do.

  The present invention adopts the following configuration as means for solving the above-described problems.

  A first invention is a printed wiring board in which four pads to which terminals of a surface-mount type three-terminal capacitor are connected are arranged in a cross shape, and at least one of the pads is cut at a corner near the adjacent pad. A configuration is adopted in which the shape is a lacking plan view.

  According to a second invention, in the first invention, a ground pattern pad provided in the ground pattern as the pad is provided, and the ground pattern pad has a plan view shape in which a corner portion close to the adjacent pad is cut out. The configuration that is said to be adopted.

  A third invention is an electronic board comprising a printed wiring board in which four pads to which terminals of a surface mount type three-terminal capacitor are connected are arranged in a cross, and a three-terminal capacitor mounted on the printed wiring board. Thus, a configuration is adopted in which the printed wiring board includes the printed wiring board according to the first or second invention.

  According to the printed wiring board of the present invention, the shape of the pad to which the terminal of the three-terminal capacitor is connected is a shape in which a corner near the adjacent pad is notched. For this reason, the distance between adjacent pads becomes longer. Therefore, when the three-terminal capacitor is attached, even if the arrangement position of the three-terminal capacitor is shifted in the rotation direction, it is possible to prevent the terminals of the three-terminal capacitor from contacting both adjacent pads. Therefore, according to the printed wiring board of the present invention, it is possible to prevent the signal pattern or the like and the ground pattern from being short-circuited even when the three-terminal capacitor is rotated at the time of attachment.

It is the enlarged plan view which expanded a part of electronic board in one embodiment of the present invention. It is a top view of a three-terminal capacitor with which an electronic substrate in one embodiment of the present invention is provided. It is an enlarged plan view which shows the modification of the printed wiring board with which the electronic board in one Embodiment of this invention is provided. It is an enlarged plan view which shows the modification of the printed wiring board with which the electronic board in one Embodiment of this invention is provided.

  Hereinafter, an embodiment of a printed wiring board wiring electronic board according to the present invention will be described with reference to the drawings. In the following drawings, the scale of each member is appropriately changed in order to make each member a recognizable size.

  FIG. 1 is an enlarged plan view in which a part of the electronic substrate 1 of the present embodiment is enlarged. As shown in this figure, the electronic substrate 1 of this embodiment includes a printed wiring board 2 and a three-terminal capacitor 3. In FIG. 1, the three-terminal capacitor 3 is indicated by a broken line. In FIG. 1, only the three-terminal capacitor 3 is illustrated as an electronic component. However, the electronic substrate 1 includes an electronic component (IC or the like) mounted on the printed wiring board 2 in addition to the three-terminal capacitor 3. I have.

  The printed wiring board 2 is a multilayer substrate in which a metal wiring layer is formed over a plurality of layers with respect to an insulating layer made of an epoxy resin or the like. In the present embodiment, the printed wiring board 2 includes a ground pattern 2a and a signal pattern 2b as metal wiring layers provided on the surface.

  The ground pattern 2a is, for example, a wiring pattern that is grounded by being connected to a metal case that houses the electronic substrate 1 of the present embodiment, and is set wider than the signal pattern 2b in order to reduce the resistance value. . The ground pattern 2a is connected to an unillustrated intermediate layer or back layer (metal wiring layer) through a plurality of vias 2c. A resist film is formed on the ground pattern 2a so as to avoid the pad area. Such a region where the resist film is not formed on the ground pattern 2 a is used as a pad for connecting the ground pattern 2 a and the three-terminal capacitor 3. Hereinafter, this region is referred to as a ground pattern pad 2a1.

  The ground pattern pads 2 a 1 are provided at two locations according to the ground terminals 3 c of the three-terminal capacitor 3. As shown in FIG. 1, these ground pattern pads 2a1 have a plan view shape in which corners 2a2 close to adjacent pads (signal pattern pads 2b1 described later) are cut out. Each of the ground pattern pads 2a1 has a shape in which two corners 2a2 are cut out. As a result, the plan view shape is such that the oblique side connecting the upper base and the lower base is directed to the signal pattern pad 2b1. It has a trapezoidal shape. As shown in FIG. 1, the two ground pattern pads 2 a 1 are symmetric with respect to the three-terminal capacitor 3.

  The signal pattern 2b is a wiring pattern connected to the input / output terminals (input terminal 3a and output terminal 3b) of the three-terminal capacitor 3, for example. A resist film is formed on the signal pattern 2b so as to avoid the pad area. Such a region on the signal pattern 2b where the resist film is not formed is used as a pad for connecting the signal pattern 2b and the three-terminal capacitor 3. Hereinafter, this region is referred to as a signal pattern pad 2b1.

  The signal pattern pads 2b1 are provided at two locations according to the input / output terminals (input terminal 3a and output terminal 3b) of the three-terminal capacitor 3. As shown in FIG. 1, these signal pattern pads 2b1 have a substantially square shape in plan view. These two signal pattern pads 2b1 are vertically symmetrical with respect to the three-terminal capacitor 3.

  As described above, in the electronic substrate 1 of the present embodiment, the printed wiring board 2 includes four pads (two ground pattern pads 2a1 and two signal pattern pads 2b1). As shown in FIG. 1, these pads are arranged in a cross so that the two ground pattern pads 2a1 face each other and the two signal pattern pads 2b1 face each other. Note that the four pads arranged in a cross shape have a point-symmetric shape as a whole with reference to the center of the cross arrangement.

  The three-terminal capacitor 3 is a surface-mounted electronic component for removing high-frequency noise that has entered the signal pattern 2b, and includes an input terminal 3a, an output terminal 3b, and two ground terminals 3c. The three-terminal capacitor 3 has a rectangular shape in plan view, an input / output terminal (input terminal 3a and output terminal 3b) is provided in each of the short pieces of the three-terminal capacitor 3, and a ground terminal 3c is the three-terminal capacitor 3. It is provided on each of the long sides.

  In such a three-terminal capacitor 3, the input / output terminals (the input terminal 3a and the output terminal 3b) are soldered to the signal pattern pad 2b1, and the ground terminal 3c is soldered to the ground pattern pad 2a1. It is mounted on the wiring board 2.

  In the electronic substrate 1 and the printed wiring board 2 in the present embodiment as described above, the shape of the ground pattern pad 2a1 to which the ground terminal 3c of the three-terminal capacitor 3 is connected is the adjacent pad (signal pattern pad 2b1). The corner portion 2a2 close to the shape is cut out. For this reason, the separation distance between the adjacent ground pattern pad 2a1 and the signal pattern pad 2b1 becomes longer than the case where the corner 2a2 is not cut. Therefore, when the three-terminal capacitor 3 is attached, even if the arrangement position of the three-terminal capacitor 3 is shifted in the rotation direction, the terminals of the three-terminal capacitor 3 (input terminal 3a, output terminal 3b, and ground terminal 3c) are It is possible to prevent contact with both the adjacent ground pattern pad 2a1 and signal pattern pad 2b1. Therefore, according to the electronic substrate 1 and the printed wiring board 2 in the present embodiment, even when the three-terminal capacitor 3 is rotated at the time of attachment, it is possible to prevent the signal pattern and the ground pattern from being short-circuited. it can.

  Further, in the electronic substrate 1 and the printed wiring board 2 in the present embodiment, the corner 2a2 of the pad (ground pattern pad 2a1) provided in the ground pattern 2a wider than the signal pattern 2b is cut out. For this reason, compared with the case where the corner of the pad (signal pattern pad 2b1) provided in the narrow signal pattern 2b is cut out, the corner can be easily cut out.

  In the electronic circuit board 1 of the present embodiment, the printed wiring board 2 has four pads (two ground pattern pads 2a1 and two signal pattern pads 2b1) as a whole with reference to the center of the cross arrangement. The arrangement and shape are set so as to have a point-symmetric shape. For this reason, when the three-terminal capacitor 3 is mounted on the printed wiring board 2 by reflow soldering, the force received by the three-terminal capacitor 3 from the melted solder becomes equal in the horizontal direction and the vertical direction in plan view. It is possible to prevent the force to rotate the terminal capacitor 3 from being biased. Therefore, it is possible to prevent the three-terminal capacitor 3 from rotating in plan view.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are examples, and various modifications can be made based on design requirements and the like without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the configuration in which the ground pattern pad 2a1 is cut out so as to have a trapezoidal shape in plan view has been described. However, the present invention is not limited to this, and as shown in FIG. 3A, a configuration in which the ground pattern pad 2a1 is cut out so as to have a semicircular shape in plan view is adopted. It is also possible. Further, as shown in FIG. 3B, it is possible to adopt a configuration in which the ground pattern pad 2a1 is cut out so that the plan view has a substantially trapezoidal shape with a hypotenuse curved in an arc shape. It is. Further, as shown in FIG. 3C, it is possible to adopt a configuration in which the ground pattern pad 2a1 is cut out so that the shape in plan view is T-shaped.

  In the above-described embodiment, the configuration in which the corner 2a2 of the ground pattern pad 2a1 is notched has been described. However, the present invention is not limited to this. For example, as shown in FIG. 4A, the corner of the signal pattern pad 2b1 is notched, or as shown in FIG. It is also possible to adopt a configuration in which the corners of both the ground pattern pad 2a1 and the signal pattern pad 2b1 are cut out.

  DESCRIPTION OF SYMBOLS 1 ... Electronic substrate, 2 ... Printed wiring board, 2a ... Ground pattern, 2a1 ... Ground pattern pad (pad), 2a2 ... Corner part, 2b ... Signal pattern, 2b1 ... Signal pattern pad ( Pad), 2c ... via, 3 ... three-terminal capacitor, 3a ... input terminal, 3b ... output terminal, 3c ... ground terminal

Claims (3)

A printed wiring board in which four pads to which terminals of a surface mount type three-terminal capacitor are connected are arranged in a cross shape,
At least one of the pads has a planar view shape in which a corner near the adjacent pad is cut out. A ground pattern pad provided in a ground pattern as the pad is provided,
The printed wiring board according to claim 1, wherein the ground pattern pad has a shape in plan view in which a corner near the adjacent pad is cut out. An electronic board comprising a printed wiring board in which four pads to which terminals of a surface mounting type three-terminal capacitor are connected are arranged in a cross, and a three-terminal capacitor mounted on the printed wiring board,
An electronic board comprising the printed wiring board according to claim 1 or 2 as the printed wiring board.

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