JP2001326429A - Printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printed wiring board that has a configuration for preventing deformation such as warpage and twisting from being generated, and allows a dummy pattern to be designed easily. SOLUTION: A printed wiring board 30 is composed of a circuit body region 32 where a wiring pattern made of copper foil is formed, and a so-called disposal board region 34 that is disposed as non-production region without forming any wiring patterns. Also in the disposal board region, as a dummy pattern, at least one portion of the same wiring pattern as the wiring pattern that is formed in the circuit body region is formed. The dummy pattern of the disposal board region is formed by etching the copper foil by the same process as the wiring pattern in the circuit body region, or the like. The ratio of remaining copper becomes nearly the same between the disposal board and circuit body regions, thus allowing the substrate to indicate the same behavior to change in temperature over both the regions, dispersing stress onto the entire surface of the printed wiring board, preventing the stress from being easily concentrated at a specific place on the printed wiring board, and hence preventing the deformation such as the warpage and twisting from being generated in the printed wiring board.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printed circuit board having a circuit main body region in which a wiring pattern is formed and manufactured, and a so-called discarded plate region in which the wiring pattern is not formed as a non-product portion. More specifically,
The present invention relates to a printed wiring board having a configuration in which deformation such as warpage or twisting does not occur in a mounting process.

[0002]

2. Description of the Related Art With the miniaturization of semiconductor devices and the miniaturization of electric / electronic devices utilizing semiconductor devices, high-density mounting of printed wiring boards on which semiconductor devices are mounted and incorporated in electric / electronic devices has been required. Has been requested. Printed wiring boards
It is formed by mounting circuit elements such as semiconductor chips and resistance elements on a printed wiring board on which a wiring pattern is formed. In a mounting step of mounting a circuit element on a printed wiring board, the circuit element is mounted by a bonding method such as solder bonding or thermocompression bonding. Since the circuit elements are mounted at a high density as the printed wiring board is mounted at a high density, the amount of heat per unit area of the printed wiring board generated when the circuit elements are joined increases. The generated heat causes thermal deformation such as warping and twisting of the printed wiring board, and the deformation remains on the printed wiring board as a product, which greatly affects the product yield of the printed wiring board.

On the printed wiring board 10, as shown in FIG. 2, a wiring pattern is usually formed, and a circuit body region 12 to be commercialized and a circuit pattern around the circuit body region 12 are formed. And a so-called discard plate region 14 which is a region cut off without performing. Therefore, conventionally, as one of measures for preventing deformation of the printed wiring board such as warpage and twist, a printed wiring board in which a dummy pattern is formed in a discarded plate area of the printed wiring board has been proposed. For example, as a first countermeasure, as shown in FIG. 3, the printed wiring board 16 of the conventional example 1 has a so-called solid pattern 18 in which copper foil is adhered to one entire surface of the discard plate area 14 except for the circuit body area 12. An attempt has been made to prevent the printed wiring board from being deformed by forming the board so that the rigidity of the board is made substantially uniform over the entire surface of the circuit body area 12 and the discarded board area 14.

As a second countermeasure, as shown in FIG. 4, in a printed wiring board 20 of the prior art 2, a copper foil 22 is attached to the entire surface of one side of the discard plate area 14 except for the circuit body area 12 by solid bonding. Next, the copper foil is removed vertically and horizontally in a slit shape to form a region 24 exposing the substrate base, and the expansion and contraction of the copper foil solid pattern 22 attached to the discarded plate region 14 is absorbed by the slit-shaped exposed region 24. Thus, a method of preventing the deformation by making the rigidity of the substrate more uniform over the entire surface of the substrate has been attempted. The slit-shaped exposed area 24 is formed in the circuit body area 12 of the printed wiring board by etching or the like.
Is formed simultaneously with the pattern formation.

Further, as a third measure, when a dummy pattern is formed of copper foil in the discarded plate area, the ratio of the area where the dummy pattern exists to the area where the dummy pattern does not exist is determined by the existence of the wiring pattern in the circuit body area. There has been proposed a printed wiring board on which a dummy pattern is arranged so as to have a ratio equal to the area of the non-existent area. Hexagons, triangles, pentagons, octagons, trapezoids, and the like have been proposed as dummy patterns.

[0006]

However, the conventional countermeasures for preventing the deformation of the printed wiring board have respective problems as described below. In the first countermeasure, since the copper foil is solidly attached to the entire surface of one side of the discarded plate region 14, free expansion and contraction of the printed wiring board itself caused by a change in temperature and humidity is hindered. In addition, the printed wiring board is deformed such as warping or twisting. According to the second measure, although the expansion and contraction of the printed wiring board itself can be absorbed to some extent by the slit area provided in the copper foil solid pattern, the printed wiring board is bent along the boundary between the slit area and the copper foil area. May occur. Furthermore, since the rigidity of the slit region formed linearly is lower than the rigidity of the copper foil region, the load acting on the copper foil region is concentrated on the slit region, and the slit region is easily broken.

In the third countermeasure, if the area where the dummy pattern does not exist is present linearly and continuously, similar to the second countermeasure, along the boundary between the area where the dummy pattern does not exist and the dummy pattern area. Therefore, there is a concern that the printed wiring board may be bent. Therefore, the dummy pattern must be arranged so that the portion where the dummy pattern does not exist does not exist linearly and continuously. Further, every time the design of the printed wiring board changes, the pattern occupancy of the circuit wiring portion must be obtained, and the dummy pattern must be arranged in the discarded board area so as to have the same residual copper rate as the circuit body area. Therefore, it is necessary to design a dummy pattern for each printed wiring board, and the dummy pattern becomes a complicated pattern, so that there is a problem that the number of steps for designing the dummy pattern increases.

It is an object of the present invention to provide a printed wiring board having a configuration in which deformation such as warpage or twisting does not occur and in which a dummy pattern can be easily designed.

[0009]

In order to achieve the above object, a printed wiring board according to the present invention has a wiring pattern formed therein, a circuit body region to be commercialized, and a wiring pattern formed as a non-product portion. In a printed wiring board having a so-called discarded plate area, at least a part of the same wiring pattern as the dummy pattern is also formed as a dummy pattern in the discarded plate area using the same wiring material. It is characterized by being formed.

In the present invention, "at least a part of the same wiring pattern as the wiring pattern formed in the circuit body region"
Is formed as a dummy pattern in the discarded board area because, when the discarded board area is smaller than the circuit main body area, it is a part of the wiring pattern, and the discarded board area has the same area as the circuit main body area. Sometimes, the wiring pattern is almost all, and when the discard plate area is wider than the circuit body area, it means that the wiring pattern is repeated. As long as the material of the wiring pattern and the material of the dummy pattern are the same, the material of the wiring pattern and the dummy pattern includes:
Although there is no limitation, practically, the material of the wiring pattern and the dummy pattern is a copper foil. Further, there is no limitation on the pattern shape of the wiring pattern in the circuit body region, the wiring width of the wiring pattern, and the like.

In the present invention, by forming at least a part of the wiring pattern in the circuit body region as a dummy pattern in the discard plate region, the residual copper ratio is inevitably substantially between the discard plate region and the circuit body region. Become equal. As a result, in the printed wiring board mounting process, the temperature distribution of the printed wiring board becomes uniform over the entire surface of the board, that is, in the discarded board area and the circuit main body area. Both regions show the same behavior with respect to temperature change. Incidentally, the residual copper ratio is an area where a metal foil, for example, a wiring pattern made of copper foil exists, and the copper foil is etched,
It refers to the ratio to the area where no copper foil is present. Therefore, the thermal stress acting in the mounting process is dispersed over the entire surface of the printed wiring board and does not concentrate on a specific portion of the printed wiring board, so that the printed wiring board is unlikely to be warped or twisted.

Further, since at least a part of the wiring pattern in the circuit body region is formed as a dummy pattern, it is not necessary to newly design a dummy pattern, so that the man-hour for designing the printed wiring board can be reduced as a whole. .

[0013]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. Embodiment This embodiment is an example of an embodiment of a printed wiring board according to the present invention, and FIG. 1 is a plan view showing a configuration of the printed wiring board of this embodiment. As shown in FIG. 1, the printed wiring board 30 of this embodiment has a circuit body region 3 in which a wiring pattern made of copper foil is formed,
2, around the circuit body region 32, which is cut off as a non-product region without forming a wiring pattern;
And a so-called discard plate area 34.

In this embodiment, the discard plate area 34 is also
As the dummy pattern, at least a part of the same wiring pattern as the wiring pattern formed in the circuit body region 32 is formed of the same wiring material, that is, a copper foil of the same thickness and the same purity. The dummy pattern of the discard plate area 34 is
It is formed by etching a copper foil in the same step as the step of forming the wiring pattern in the circuit body region 32.

In the present embodiment, by forming at least a part of the wiring pattern of the circuit body region 32 as a dummy pattern in the discarded plate region 34,
The residual copper ratio becomes substantially equal between the discarded plate region 34 and the circuit body region 32. As a result, in the mounting process of the printed wiring board 30, the temperature distribution of the printed wiring board becomes uniform over the entire surface of the board, that is, in the discarded board area 34 and the circuit body area 32. 3
4 and the circuit body region 32 show the same behavior with respect to a temperature change. Therefore, the thermal stress generated at the time of mounting is dispersed over the entire surface of the printed wiring board and does not concentrate on a specific portion of the printed wiring board, so that the printed wiring board is unlikely to be warped or twisted.

[0016]

According to the present invention, by forming at least a part of the wiring pattern of the circuit body region as a dummy pattern in the waste plate region, the residual copper ratio is inevitably reduced. And becomes almost equal. As a result, in the mounting process of the printed wiring board, the temperature distribution of the printed wiring board becomes uniform over the entire surface of the board, that is, in the discarded board area and the circuit main body area. Shows the same behavior with respect to temperature change in both regions. Therefore, the thermal stress at the time of mounting is dispersed over the entire surface of the printed wiring board and is not concentrated on a specific portion of the printed wiring board, so that the printed wiring board is unlikely to be warped or twisted. Further, since at least a part of the wiring pattern in the circuit body region is formed as a dummy pattern, it is not necessary to newly design a dummy pattern. Therefore, the overall design man-hour of the printed wiring board can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view illustrating a configuration of a printed wiring board according to an embodiment.

FIG. 2 is a plan view illustrating a configuration of a printed wiring board.

FIG. 3 is a plan view showing a configuration of a printed wiring board of Conventional Example 1.

FIG. 4 is a plan view showing a configuration of a printed wiring board of Conventional Example 2.

[Explanation of symbols]

10 ... printed wiring board, 12 ... circuit body area, 1
4 ... discarded plate area, 16 ... printed wiring board of Conventional Example 1, 18 ... solid pattern, 20 ... printed wiring board of Conventional Example 2, 22 ... solid copper foil pattern, 24 ... slit-shaped exposed area , 30... The printed wiring board of the embodiment, 32... The circuit body area, 34.

Claims (2)

[Claims] 1. A printed circuit board having a circuit main body region on which a wiring pattern is formed and commercialized and a so-called discarded plate region where no wiring pattern is formed as a non-product portion, wherein the discarded plate region is also provided. A printed wiring board, wherein at least a part of the same wiring pattern as the dummy pattern in the circuit body region is formed of the same wiring material. 2. The printed wiring board according to claim 1, wherein the wiring pattern and the dummy pattern are formed of copper foil.