JP2013026236A - Circuit device and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a standing wave at a pattern for a power supply from occurring and suppress level of unwanted radiation in a multilayer printed wiring board.SOLUTION: A multilayer printed wiring board is provided with a plurality of slits 2 between facing two parallel sides among an outer periphery of a power supply land 1. Concerning a shape of a border line of a missing portion formed by the slits 2 in the power supply land 1, any arbitrary two missing parts do not have a line segment against which a same perpendicular line 9 can be drawn between border lines. A border line of a missing part does not have a line segment against which a same perpendicular line can be drawn between any arbitrary outer periphery of the power supply land 1 and the border line.

Description

  The present invention relates to a pattern shape of a multilayer printed wiring board constituting a circuit device.

In recent years, multilayer printed wiring boards having a plurality of layers have become mainstream as the component mounting density increases, and a dedicated layer for power supply is often disposed on the inner layer. In the power supply dedicated layer, lands of a plurality of power supply systems are prepared, and the impedance of the end portions (outer periphery) of each power supply land changes greatly. The traveling wave transmitted through the power supply land is reflected, but when the outer peripheries face each other in parallel, the reflected wave is superimposed, so that a standing wave is generated at a specific frequency. In other words, the presence of a resonance frequency in the power supply circuit causes unnecessary radiation at a specific frequency. FIG. 9 is an explanatory view schematically showing the state. The length of the power land 200 is L, and the wavelength of the standing wave is λ. Length L is (1/4) · λ, (3/4) · λ, (5/4) · λ, that is, a standing wave with a frequency equivalent to an odd multiple of a quarter wavelength is generated. To do.
In order to cope with this, a method of placing a pass capacitor to the ground (GND) in the power supply land is known. Patent Document 1 proposes a method for suppressing Q (sharpness) by increasing the impedance to a standing wave by disposing an element having an internal loss such as a resistor. Alternatively, by reducing the size of the power land and driving the above-described specific frequency to a higher frequency, or as disclosed in Patent Document 2, the outer shape of the power land is configured with a short side or circular. A method has also been proposed. Patent Document 3 discloses a configuration in which a slit is provided in a signal layer instead of a power supply layer.

Japanese Patent Laid-Open No. 11-145569 Japanese Patent Laid-Open No. 9-246681 Japanese Patent Laid-Open No. 11-317572

  By the way, in recent years, there is a device called BGA (Ball Grid Array) for further higher density, which has a terminal of several hundred pins in a lattice pattern with a narrow pitch of, for example, a 1 mm interval. In this case, in order to be restricted by the wiring drawn out from each terminal, it is impossible to arbitrarily provide Via (interlayer connection plating hole) for connecting from the power supply land to the surface layer. For this reason, it is difficult to place a capacitor at an effective position with respect to a method of arranging a pass capacitor to GND in the power supply land. In addition, the method of arranging an element having an internal loss such as a resistor is effective for a linear power supply line, but is not suitable for a square BGA power land.

Further, in recent years, the method of driving the generated standing wave frequency to a higher frequency by reducing the size of the power supply land has been required to further reduce the size of the power supply land. This is because the frequency band that is subject to regulation of unwanted radiation has spread to a high frequency range. However, due to the circuit design, it is not possible to make a power land smaller than the size of the BGA package. Also, the method of configuring the outer peripheral shape of the power supply land with short sides or making it circular is not suitable for high density because a power supply pattern that is slightly larger than the BGA package shape is required. In this case, it is impossible to fundamentally prevent the occurrence of standing waves by the opposing parallel outer periphery.
An object of the present invention is to prevent the generation of standing waves in a power supply pattern and to suppress the level of unnecessary radiation.

  In order to solve the above-described problem, an apparatus according to the present invention is a circuit device including a multilayer printed wiring board in which a power supply pattern is formed, and a boundary line between any two missing portions formed in the power supply pattern is In addition, there is no line segment that can draw the same perpendicular line between them.

  According to the present invention, it is possible to prevent the occurrence of standing waves in the power supply pattern and to suppress the level of unnecessary radiation.

It is the schematic which shows the structural example of the circuit apparatus using the multilayer printed wiring board concerning this invention. It is the figure (A) which illustrates the power supply land pattern which concerns on 1st Embodiment of this invention, and explanatory drawing (B), (C) of the relative positional relationship of a slit. It is a figure which illustrates the power supply land pattern which concerns on the modification of 1st Embodiment of this invention. It is a figure which illustrates the power supply land pattern which concerns on 2nd Embodiment of this invention. It is explanatory drawing which illustrates the relative positional relationship of parallel line segments in the outer periphery which opposes. It is a figure which illustrates the power supply land pattern which concerns on the 1st modification of 2nd Embodiment. It is a figure which illustrates the power supply land pattern which concerns on the 2nd modification of 2nd Embodiment. It is a figure which illustrates the power supply land pattern which concerns on the 3rd modification of 2nd Embodiment. It is explanatory drawing regarding generation | occurence | production of a standing wave.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is an exploded perspective view illustrating a six-layer printed wiring board as a circuit device using a multilayer printed wiring board. In this example, a wiring board is shown in which five substrates 100 to 104 are stacked in the vertical direction, and a wiring pattern is formed on the upper surface of each substrate. Although not shown in the figure, since the wiring pattern is also formed on the back surface of the base material 104, there are a total of six wiring pattern layers. The wiring pattern layer 103A on the upper surface of the base material 103 is a layer dedicated to power supply. In the drawing, for convenience of explanation, a wiring pattern is shown on the upper surface of each of the substrates 100 to 104. However, in actual manufacturing, a wiring pattern is formed only on one side of the substrate and superimposed. Not necessarily.

[First Embodiment]
Next, a first embodiment of the present invention will be described. The first embodiment relates to the boundary line of the missing portion formed in the power supply pattern, that is, the shape of the boundary line between the conductive region and the missing region. This missing portion is formed, for example, by arranging a plurality of slits between two opposing parallel sides in the outer periphery of the power supply pattern. In this case, any two missing portions have a shape in which the same perpendicular cannot be drawn between the boundary lines of the two.

FIG. 2A illustrates a power land pattern according to the first embodiment of the present invention.
In the power land 1 made of copper foil, a plurality of straight slits (eight in FIG. 1) 2 are formed. These slits 2 are arranged so as to block all standing waves generated by the portions facing the outer periphery of the power supply land 1 in parallel. That is, any two slits 2 basically have a relative positional relationship in which the same perpendicular cannot be drawn. This relationship will be described with reference to FIGS. 2B and 2C.

FIG. 2B shows a relative positional relationship in which a perpendicular line 9 can be drawn between the first slit 2A and the second slit 2B. In this case, since the reflection of the traveling wave is repeated between the two, a standing wave is generated. On the other hand, FIG. 2C shows a relative positional relationship in which the first slit 2A and the second slit 2B are parallel to each other but the same perpendicular line 9 cannot be drawn between them. That is, in this example, the foot of the perpendicular line 9 is determined in the second slit 2B, but the perpendicular line 9 can be lowered only on the extension line of the first slit 2A. In such a relative positional relationship, no standing wave is generated. Also, any of the slits 2 shown in FIG. 2A is formed in a linear shape that is inclined with respect to the outer periphery of the power land 1, so that it is not parallel to the outer periphery of the power land 1.
If the length of the slit 2 (see S in FIG. 2) is longer than necessary, the power land is divided and the power impedance increases, which is not preferable in terms of circuit characteristics. For this reason, it is set to 1/3 or less of the length of one side of a power supply land. Further, with respect to the width of the slit 2 (see W in FIG. 2), a sufficient effect can be obtained even if it is 0.5 mm or less, for example, because it is intended to prevent traveling waves from being reflected.
Although illustration is omitted, the power land pattern is connected to other layers via, and is connected to an electronic component that receives power supply, a capacitor disposed between the power source and GND on the circuit, or the like. The linear wiring pattern to the power supply unit is arranged in any layer.
According to the first embodiment, the occurrence of standing waves is prevented by forming a plurality of slits so as to have a relative positional relationship in which the same perpendicular cannot be drawn in any combination of the boundary lines of the missing portions. be able to. Therefore, the generation of standing waves can be prevented even with a rectangular power supply pattern, and the level of unnecessary radiation can be suppressed.

  Next, modifications of the first embodiment will be described.

(First modification)
FIG. 3A illustrates a power land pattern according to the first modification. Hereinafter, differences from the above-described example will be described, and the description of the same components will be omitted by using the already used reference numerals. Note that the method of omitting such description is the same in other embodiments described later.
A plurality of arc-shaped slits 7 (seven in this example) are formed in the power land 1. These slits 3 are arranged so as to block all standing waves generated by the portions facing the outer periphery of the power supply land 1 in parallel. Since the slit 3 has an arc shape, there is no portion parallel to each other between arbitrary slits, and it is not parallel to the outer periphery.
According to the first modification, by forming an arc-shaped slit in the power land pattern, the boundary line between the portion where the power land pattern exists and the missing portion can be in a relationship that is not parallel to each other.

(Second modification)
FIG. 3B illustrates a power land pattern according to the second modification. In the power land 1, a plurality of (six in this example) slits 4 bent in a curved shape are formed. These slits 4 have a shape bent in a U-shape or a shape curved in an S-shape, and a linear portion is also present therein. However, any two straight portions are basically not parallel to each other. Alternatively, even if there are linear portions that are parallel to each other, as described with reference to FIG. 2C, a relative positional relationship in which the same perpendicular cannot be drawn with respect to the two linear portions. Further, the curved portions of the arbitrary slits 4 do not have portions that are parallel to each other, and are not parallel to the outer periphery of the power land 1.
According to the second modification, a slit that is bent in the power land pattern is provided, and a relative positional relationship in which the same perpendicular cannot be drawn between the straight portions can be obtained.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. The second embodiment relates to the shape of the outer periphery of the power supply pattern, and is characterized in that the same perpendicular cannot be drawn between any two outer periphery.

FIG. 4 illustrates a power land pattern according to the second embodiment of the invention.
The shape of the four sides (outer periphery) of the power land 1 is a sawtooth shape, and all are zigzag lines. The slopes of the line segments constituting the zigzag line are uniform within each side, but are different for every four sides. For example, among the constituent line segments of the zigzag line, for the line segment from the upper left to the lower right in FIG. 4, the line segment 11 on the upper side, the line segment 21 on the lower side, the line segment 31 on the left side, and the line on the right side There are four ways of minute 41. The slopes of these line segments are set to have different values. Thereby, the relationship where the line segments of each side do not become parallel is obtained. Similarly, for the line segment from the lower left to the upper right in FIG. 4, there are four types of line segment 12 on the upper side, line segment 22 on the lower side, line segment 32 on the left side, and line segment 42 on the right side. Since each has a different inclination, any two line segments are not parallel to each other.

  FIG. 5 exemplifies a case where line segments having the same inclination exist in the constituent line segments of two opposing sides (in this example, the left side 30 and the right side 40) of the outer periphery of the power supply land. In the example of FIG. 5, line segments from the upper left to the lower right are in a parallel relationship, and the same perpendicular line 50 can be drawn between the line segments. That is, if the downward-sloping line segment constituting the left side 30 and the downward-sloping line segment constituting the right side 40 have the same inclination, they become parallel line segments that face each other, and thus standing waves that repeat reflections. Will occur. As described above, when there is a relationship in which perpendicular lines can be drawn in some combinations among the line segments that respectively constitute the opposing outer peripheries (hereinafter referred to as “opposite parallel line segment relationships”), the standing wave Will occur. Similarly, standing waves are generated when adjacent outer peripheral edges, for example, the upper side and the left side, have line segments with the same inclination and the “opposite parallel line segment relationship” occurs. In other words, if the slopes of the line segments constituting each side are set to different values for each of the four sides, the “opposing parallel line segment relationship” does not occur, so that the occurrence of standing waves can be prevented.

There is no particular restriction on the zigzag line run-out width (distance difference between peaks and valleys). However, since there is a possibility that the mounting density may be lowered when the swing width is larger than necessary as compared with the size of the device to be mounted, it is preferable to be about several mm to 10 mm in practical use.
According to the second embodiment, the outer periphery of the power supply land is formed in a sawtooth shape, and the constituent line segments are inclined differently for each side, so that the “opposite parallel line segment relationship” does not occur. Therefore, generation of standing waves can be prevented and generation of unnecessary radiation can be prevented.
Next, modified examples of the second embodiment will be described.

(First modification)
FIG. 6 illustrates a power land pattern according to the second modification. Of the outer periphery of the power land 60, only two sides (see the upper side 61 and the right side 62) are zigzag lines, and the remaining two sides (see the left side 63 and the lower side 64) are straight lines. The slopes of the line segments that make up the zigzag line have different values for each side. If one of the two opposing sides of the power land 60 is a zigzag line, the “opposing parallel line segment relationship” does not occur, so that the occurrence of standing waves can be prevented.

(Second modification)
FIG. 7A illustrates a power land pattern according to the second modification. The outer periphery of the power land 70 is formed in a wave shape with a combination of curves. Therefore, there is no parallel part between any two sides, and there is no straight line part, so there is of course no “parallel parallel line segment relationship”. Thus, by forming each side of the power supply land 70 in a curved shape, the occurrence of standing waves can be prevented.
FIG. 7B shows an example in which only two adjacent sides (see the upper side 72 and the right side 73) of the outer periphery of the power land 71 are formed by a combination of curves. The remaining two sides (see the left side 74 and the lower side 75) are linear. If one of the two opposing sides of the power land 71 is curved, the “opposing parallel line segment relationship” does not occur, so that the occurrence of a standing wave can be prevented.

(Third Modification)
FIG. 8 illustrates a power land pattern according to the third modification. Of the four sides of the power land 80, one of the two opposing sides (see the right side 81 and the lower side 82) is a bent line (a broken line). The slopes of the constituent lines of the lines are different from each other. The remaining two sides (see the upper side 83 and the left side 84) are linear, but the occurrence of standing waves can be prevented because there is no “parallel parallel line segment relationship” between the two opposing sides. Note that a gently curved curve shape may be used instead of such a bending line.

DESCRIPTION OF SYMBOLS 1 Power supply land 2, 3, 4 Slit 2A 1st slit 2B 2nd slit 9,50 Perpendicular 11,12 Line segment (upper side)
21 and 22 line segment (bottom side)
31, 32 line segment (left side)
41, 42 line segment (right side)

Claims (10)

A circuit device comprising a multilayer printed wiring board on which a power supply pattern is formed,
The circuit device characterized in that the boundary line between any two missing portions formed in the power supply pattern does not have a line segment that can draw the same perpendicular line therebetween.   The circuit device according to claim 1, wherein the missing portion is formed by arranging a plurality of slits between two opposing parallel sides of the outer periphery of the power supply pattern.   The circuit device according to claim 1, wherein the plurality of slits have curved portions.   4. The circuit device according to claim 2, wherein the plurality of slits do not have a line segment parallel to the outer periphery of the power supply pattern.   Among the plurality of slits, the first slit and the second slit having linear portions parallel to each other draw the same perpendicular line only on the extension line of the linear portion of the first slit or the second slit. 3. The circuit device according to claim 2, wherein the relative positional relationship is not possible. A circuit device comprising a multilayer printed wiring board on which a power supply pattern is formed,
The circuit device according to claim 1, wherein the shape of the outer periphery of the power supply pattern does not have a line segment that can draw the same perpendicular line between any two outer periphery.   The circuit device according to claim 6, wherein at least one of two opposing sides of the outer periphery of the power supply pattern has a sawtooth shape, and a line segment constituting this has a different slope for each outer periphery.   The circuit device according to claim 6, wherein at least one of two opposing sides of the outer periphery of the power supply pattern has a curved portion. A method of manufacturing a circuit device including a multilayer printed wiring board on which a power supply pattern is formed,
In the step of forming a missing portion in the power supply pattern, a boundary line between any two missing portions is formed so as not to have a line segment that can draw the same perpendicular line therebetween. Circuit device manufacturing method. A method of manufacturing a circuit device including a multilayer printed wiring board on which a power supply pattern is formed,
In the step of forming the power supply pattern, the outer peripheral shape is formed so as not to have a line segment that can draw the same perpendicular line between any two outer peripherals. A method of manufacturing a circuit device.

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