JP6187011B2 - Printed circuit board - Google Patents

Description

  The present invention relates to a printed circuit board having a differential line to which components are connected and a ground layer.

  In the printed circuit board, by using differential signal transmission in which signals having the same amplitude and opposite phase are propagated and communicated to the paired signal wirings, the difference between the paired signals is obtained on the signal receiving side. By reducing the amplitude of the voltage per line and pairing signals with the same amplitude and opposite phase, the radiated electromagnetic field cancels and radiation noise is suppressed, and by taking the difference of the paired signals from the outside The influence of noise can be canceled out.

  However, when the symmetry of the line structure is lost, high-speed signals cannot be transmitted, and the balance of the differential line of the communication circuit is deteriorated, so that common mode noise propagates on the differential line, and radiation from the differential line occurs. As noise increases, the noise resistance of the differential line decreases.

  For this reason, in a high-speed differential interface in which a signal includes a high frequency component, it is necessary to design a line on the substrate so as not to impair the symmetry of the line structure (for example, Patent Document 1).

  FIG. 8 is an explanatory diagram of line design of a conventional printed circuit board. In FIG. 8A, the digital signal transmission board 1 is composed of a layer on which a first conductor 2 and a second conductor 3 are mounted with a dielectric interposed therebetween, and a ground layer. The first conductor 2 and the second conductor 3 constitute a differential line, and a positive differential signal is transmitted to one conductor and a negative differential signal is transmitted to the other conductor. The island-like conductor 4 is provided in advance by patterning along the first conductor 2 and the second conductor 3, and is used for improving the balance of the differential line. For example, when the balance of the differential line is deteriorated due to a large skew between the plus signal and the minus signal, a metal foil 5 such as copper is bonded to the first conductor 2 with solder or the like, and the oscilloscope The balance of the differential line is adjusted while comparing the plus / minus signals. After the adjustment, for example, as shown in FIG. 8B, two capacitive stubs 6 are arranged. That is, it can be considered equivalent to the arrangement of the lumped constant capacitors C1 and C2 as in the circuit shown in FIG. Here, the balance of the differential line can be improved by changing the shape, position, and interval of the capacitive stub 6 to adjust the capacitance of both wirings.

JP 2008-153386 A

  In the conventional printed circuit board, when an additional circuit such as a component is mounted on the wiring, there is a problem that a prepared stub cannot be adjusted due to trial and error after creating the board and is difficult to evaluate. In addition, there is a problem in that when mounting on a substrate at a high density, there are restrictions on the positions of connecting conductors and components to be mounted, and there is no space for mounting island conductors and stubs.

  The present invention has been made to solve the above-described problems. When a component is connected to the differential line, a design is made by adjusting the capacitance with each conductor of the differential line. An object is to suppress common mode noise on the differential line, suppress radiation noise from the differential line, and improve noise resistance of the differential line by increasing the balance.

A printed circuit board according to the present invention includes a layer for mounting wiring and components and a ground layer, and a differential line comprising a first conductor and a second conductor formed in the layer for mounting the wiring and components. The first and second parts placed between the differential lines, the first connection conductor connecting the first part and the first conductor, and the second part A second connecting conductor for connecting the component and the second conductor, and the first connecting conductor and the first component are disposed between the wiring and component mounting layers and the ground layer. A first metal pattern formed at a position immediately below the first conductor or electrically connected to the first connection conductor, a position immediately below the second connection conductor and the second component are formed on, the second conductor or the second connecting conductor electrically And a second metal pattern is continued, wherein the first connecting conductor first component is arranged in the area of the first metal pattern and the second connection conductor and the second The component is disposed in the area of the second metal pattern, and the first capacitance and the second metal pattern, which are capacitances generated between the first metal pattern and the ground layer, and the A difference in the second capacitance that is a capacitance generated between the ground layer and the ground layer is within a design target range.

According to this invention , the first connection conductor and the capacitance between the first metal pattern and the ground layer and the capacitance between the second metal pattern and the ground layer are within the design target range. The capacitance was adjusted with each conductor of the differential line without considering the capacitance between the first component and the ground layer and the capacitance between the second connecting conductor and the second component and the ground layer. It can be easily designed, which facilitates increasing the balance of the differential lines for common mode noise suppression system of the differential lines.

It is a block diagram which shows an example of the printed circuit board which concerns on Embodiment 1 of this invention. It is the elements on larger scale of the model top view of the printed circuit board concerning Embodiment 1 of this invention. It is a block diagram which shows an example of the printed circuit board which concerns on Embodiment 2 of this invention. It is a block diagram which shows an example of the printed circuit board which concerns on Embodiment 3 of this invention. It is a block diagram which shows an example of the printed circuit board which concerns on Embodiment 4 of this invention. It is a block diagram which shows an example of the printed circuit board which concerns on Embodiment 5 of this invention. It is a block diagram which shows an example of the printed circuit board which concerns on Embodiment 6 of this invention. It is explanatory drawing of the track | line design of the conventional printed circuit board.

  The present invention relates to a printed circuit board having a differential line to which components are connected and a ground layer, and relates to a printed circuit board that suppresses radiation noise from the differential line and has improved noise resistance. . Embodiments of the present invention will be described below.

Embodiment 1 FIG.
A printed circuit board according to Embodiment 1 of the present invention will be described.

  1 is a block diagram showing an example of a printed circuit board according to Embodiment 1 of the present invention. 1A is a schematic plan view of the printed circuit board, and FIG. 1B is a schematic cross-sectional view taken along the line AA in FIG. 1A.

  In the figure, a printed circuit board 1 has a layer for mounting wiring and components and a ground layer. The first conductor 11 and the second conductor 12 form a differential line formed in a layer for mounting wiring and components. The first component 31 and the second component 32 are placed at positions close to each other with the differential line interposed therebetween. The first connection conductor 21 connects the first component 31 and the first conductor 11. The second connection conductor 22 connects the second component 32 and the second conductor 12. The first metal pattern 51 is formed at a position directly below the first connection conductor 21 and the first component 31 in a layer between the wiring and component mounting layers and the ground layer. The second metal pattern 52 is formed at a position directly below the second connection conductor 22 and the second component 32 in a layer between the wiring and component mounting layers and the ground layer. The first via 41 electrically connects the first conductor 11 and the first metal pattern 51. The second via 42 electrically connects the second conductor 12 and the second metal pattern 52.

  Thus, the printed circuit board 1 includes the first conductor 11, the second conductor 12, the first component 31, the second component 32, the first connection conductor 21, and the first conductor 11 as layers for mounting wiring and components. A first layer in which two connection conductors 22 are arranged, a second layer in which a first metal pattern 51 and a second metal pattern 52 are formed, and a third layer in which a ground 70 is arranged as a ground layer The first via and the second via are electrically connected between the first layer and the second layer, respectively.

  Here, when the first connection conductor 21 and the first component 31 are arranged in the area of the first metal pattern 51, the impedance between the first connection conductor 21 and the ground layer 70 is the first metal. It depends only on the area of the pattern 51.

  Similarly, when the second connection conductor 22 and the second component 32 are disposed in the area of the second metal pattern 52, the impedance between the second connection conductor 22 and the ground layer 70 is the second metal. It depends only on the area of the pattern 52.

  For example, as shown in FIG. 1A, when the first connection conductor 21 is larger than the second connection conductor 22, the balance of the differential line deteriorates, but the area of the first metal pattern 51 and By making the difference in the area of the second metal pattern 52 within the range of the design target, the balance of the differential line can be increased.

  That is, an electrostatic capacity (first capacity) generated between the first metal pattern 51 and the ground layer 70 and an electrostatic capacity (second capacity) generated between the second metal pattern 52 and the ground layer 70. ) Within the range of the design target, the balance of the differential line can be increased.

  At this time, adjusting the difference between the first capacity and the second capacity to be within the range of the design target includes adjusting the first capacity and the second capacity equally. By such adjustment, the balance of the differential line can be increased. The same applies to the description of the first embodiment.

  From here, first, the area of the first metal pattern 51 is the same as or larger than the total area of the first connection conductor 21 and the first component 31, and the area of the second metal pattern 52 is the second. A case where the connecting conductor 22 and the second component 32 are the same or larger than the total area will be described.

  As described above, the first connection conductor 21 and the first component 31 are arranged in the area of the first metal pattern 51, and the second connection conductor 22 and the second component 32 are formed of the second metal pattern. When arranged in the area, electrostatic capacitance (first capacitance) generated between the first metal pattern 51 and the ground layer 70 and static electricity generated between the second metal pattern 52 and the ground layer 70. By adjusting the difference from the electric capacity (second capacity) to be within the range of the design target, the balance of the differential line can be increased.

  At this time, examples of the adjustment target include the area of the first metal pattern 51 and the area of the second metal pattern 52.

  As described above, when the connection conductor and the component are arranged in the area of the metal pattern, only the capacitance generated between the metal pattern and the ground layer needs to be considered.

  Subsequently, if the area of the first metal pattern 51 is smaller than the combined area of the first connection conductor 21 and the first component 31, all of at least one of the first connection conductor 21 and the first component 31 are included. Alternatively, if a part is disposed outside the area of the first metal pattern 51 and the area of the second metal pattern 52 is smaller than the combined area of the second connection conductor 22 and the second component 32, the first All or a part of at least one of the two connection conductors 22 and the second component 32 may be disposed outside the area of the second metal pattern 52.

  For example, when at least a part of the first connection conductor 21 and the first component 31 is disposed outside the area of the first metal pattern 51, the portion between the portion disposed outside the area and the ground layer 70 is disposed. The electrostatic capacity generated in the step 1 is generated in addition to the electrostatic capacity generated between the first metal pattern 51 and the ground 70. Further, for example, when at least a part of the second connection conductor 22 and the second component 32 is disposed outside the area of the second metal pattern 52, the portion disposed outside the area and the ground layer 70. The capacitance generated between the second metal pattern 52 and the ground 70 is generated in addition to the capacitance generated between the second metal pattern 52 and the ground 70.

  As described above, when the connection conductor and the component are disposed outside the area of the metal pattern, it is not sufficient to consider only the capacitance generated between the metal pattern and the ground layer. It is necessary to consider the combined capacitance with the capacitance generated between the layers.

  First, the area of the first metal pattern 51 is smaller than the combined area of the first connection conductor 21 and the first component 31, and the area of the second metal pattern 52 is the second connection conductor 22 and the second connection pattern. A case where the area is smaller than the combined area of the parts 32 will be described.

  In this way, at least one part of the first connection conductor 21 and the first component 31 is disposed outside the area of the first metal pattern 51, and the second connection conductor 22 and the second component are arranged. 32 is arranged outside the area of the first metal pattern 51 in the first connection conductor 21 and the first component 31 when at least a part of the second metal pattern 52 is arranged outside the area of the second metal pattern 52. A combined capacitance (first capacitance) of the capacitance generated between the formed portion and the ground layer 70 and the capacitance generated between the first metal pattern 51 and the ground layer 70, and the second connection A capacitance generated between a portion of the conductor 22 and the second component 32 arranged outside the area of the second metal pattern 52 and the ground layer 70, and between the second metal pattern 52 and the ground layer 70. The static that occurs in By the difference between the combined capacitance of the capacitor (second capacitor) is adjusted to be within the design target, it is possible to increase the balance of the differential lines.

  At this time, as an object of adjustment, the area of the first metal pattern 51, the area of the first connecting conductor 21 and the first component 31 arranged outside the area of the first metal pattern 51, and the area The distance between the portion arranged outside the area and the ground layer 70, the area of the second metal pattern 52, and the second connection conductor 22 and the second component 32 are arranged outside the area of the second metal pattern 52. And the distance between the portion disposed outside the area and the ground layer 70.

  Next, the area of the first metal pattern 51 is the same or larger than the total area of the first connection conductor 21 and the first component 31, and the area of the second metal pattern 52 is the second connection conductor 22. A case where the area is smaller than the combined area of the second component 32 will be described.

  As described above, the first connection conductor 21 and the first component 31 are arranged in the area of the first metal pattern 51, and at least one of the second connection conductor 22 and the second component 32. When the portion is disposed outside the area of the second metal pattern 52, the capacitance (first capacitance) generated between the first metal pattern 51 and the ground layer 70, the second connection conductor 22 and The electrostatic capacitance generated between the portion of the second part 32 arranged outside the area of the second metal pattern 52 and the ground layer 70 and the static electricity generated between the second metal pattern 52 and the ground layer 70. By adjusting the difference between the capacitance and the combined capacitance (second capacitance) to be within the design target range, the balance of the differential line can be increased.

  At this time, as the adjustment target, the area of the first metal pattern 51 and the area of the second metal pattern 52 and the area outside the second metal pattern 52 in the second connection conductor 22 and the second component 32 are included. The area of the part arrange | positioned to is mentioned.

  The first conductor and the related first component, the first connecting conductor, the first metal pattern, the second conductor and the related second component, and the second connection described so far. For the conductor and the second metal pattern, for example, even if the interpretation of the relationship between the arrangement of the first and second metal patterns and the size of the area is reversed, the difference is similarly adjusted by adjusting according to the condition contents. The balance of the line can be increased.

  FIG. 2 is a partially enlarged view of a schematic plan view of the printed circuit board according to Embodiment 1 of the present invention. Based on the drawings, the shape of the metal pattern and the arrangement of vias will be described. First, FIG. 2A shows the first conductor 11, the first component 31, the first connection conductor 21, the first metal pattern 51, the first metal pattern 51 in the schematic plan view of the printed circuit board of FIG. 2 is a partially enlarged view of one via 41. FIG. Here, the first via 41 is arranged on the first conductor 11 so as to connect the first conductor 11 of the first layer and the first metal pattern 51 of the second layer. . At this time, the first metal pattern 51 only needs to be arranged in a shape that extends directly below the first via 41 in order to connect to the first conductor 11. Moreover, the modification of the shape of the 1st metal pattern 51 and arrangement | positioning of the 1st via | veer 41 is shown to (D) from FIG. FIG. 2B shows an example in which the shape of the first metal pattern 51 is changed without changing the arrangement of the first vias 41 from FIG. FIG. 2C shows an example in which the arrangement of the first via 41 is changed on the first connection conductor 21 without changing the shape of the first metal pattern 51. FIG. 2D shows an example in which both the shape of the first metal pattern 51 and the arrangement of the first vias 41 are changed. At this time, the first metal pattern 51 only needs to be arranged in a shape that extends directly below the first via 41 in order to connect to the first connection conductor 21. The shape of the first metal pattern 51 is not limited to the rectangle as shown in FIGS. 2A, 2C, and 2D or the shape as shown in FIG. A shape cut by a curve may be used, and the first conductor 11 or the first connection conductor 21 of the first layer and the first metal pattern 51 of the second layer are electrically connected via the first via 41. I can do it. Further, the shape of the second metal pattern 52 and the arrangement of the second via 42 in the second conductor 12, the second component 32, the second connection conductor 22, the second metal pattern 52, and the first via 42. This can be explained in the same way.

  In the first embodiment, a pair of first component 31, second component 32, first connection conductor 21, first connection conductor 21 with respect to the first conductor 11 and the second conductor 21 forming the differential line. The mounting of the two connection conductors 22, the first metal pattern 51, and the second metal pattern 52 has been described. There may be cases where multiple wirings or other parts are mounted on this printed circuit board, or connection conductors or parts may be mounted only on one side of the differential line. The overall balance can be increased by improving the balance.

  In the first embodiment, the mounting of the printed circuit board having a three-layer structure has been described. However, the printed circuit board is not limited to the three layers and includes other layers not directly used in the mounting portion described here. It can also be applied to.

  As described above, according to the first embodiment of the present invention, the first component, the first connection conductor, the second component with respect to the first conductor and the second conductor forming the differential line, The first metal pattern and the second metal pattern are formed in the same layer between the layer on which the second connection conductor is mounted and the ground layer, and the difference in capacitance between both sides of the differential line is within the design target range. Therefore, by increasing the balance of the differential line, common mode noise on the differential line is suppressed, radiation noise from the differential line is suppressed, and the resistance of the differential line is improved. Noise characteristics can be improved.

Embodiment 2. FIG.
A printed circuit board according to Embodiment 2 of the present invention will be described.

  3 is a block diagram showing an example of a printed circuit board according to Embodiment 2 of the present invention. 3A is a schematic plan view of the printed circuit board, and FIG. 3B is a schematic cross-sectional view taken along the line BB in FIG. 3A.

  In the figure, a printed circuit board 1 has a layer for mounting wiring and components and a ground layer. The first conductor 11 and the second conductor 12 form a differential line formed in a layer for mounting wiring and components. The first component 31 and the second component 32 are placed at positions close to each other with the differential line interposed therebetween. The first connection conductor 21 connects the first component 31 and the first conductor 11. The second connection conductor 22 connects the second component 32 and the second conductor 12. The first metal pattern 51 is formed at a position directly below the first connection conductor 21 and the first component 31 in a layer between the wiring and component mounting layers and the ground layer. The second metal pattern 52 is formed on a layer different from the layer on which the first metal pattern 51 is formed between the wiring and component mounting layers and the ground layer, directly below the second connection conductor 22 and the second component 32. It is formed at the position. The first via 41 electrically connects the first conductor 11 and the first metal pattern 51. The second via 42 electrically connects the second conductor 12 and the second metal pattern 52.

  Thus, the printed circuit board 1 includes the first conductor 11, the second conductor 12, the first component 31, the second component 32, the first connection conductor 21, and the first conductor 11 as layers for mounting wiring and components. A first layer in which two connection conductors 22 are arranged, a second layer in which a first metal pattern 51 is formed, a third layer in which a second metal pattern 52 is formed, and a ground layer as a ground layer 70 has a multilayer structure composed of a fourth layer, the first via is between the first layer and the second layer, and the second via is between the first layer and the third layer. Electrical connection between them.

  Here, when the first connection conductor 21 and the first component 31 are arranged in the area of the first metal pattern 51, the gap between the first connection conductor 21 of the first conductor 11 and the ground layer 70. The impedance depends on the area of the first metal pattern 51 and the distance between the first metal pattern 51 and the ground layer 70.

  Similarly, when the second connection conductor 22 and the second component 32 are disposed in the area of the second metal pattern 52, the impedance between the second connection conductor 22 and the ground layer 70 is the second metal. It depends on the area of the pattern 52 and the distance between the second metal pattern 52 and the ground layer 70.

  For example, as shown in FIG. 3A, when the first connection conductor 21 is larger than the second connection conductor 22, the balance of the differential line is deteriorated, but the area of the first metal pattern 51 and The first metal pattern 51 and the ground layer 70 are adjusted by adjusting the distance between the first metal pattern 51 and the ground layer 70, the area of the second metal pattern 52, and the distance between the second metal pattern 52 and the ground layer 70. By setting the difference between the capacitance between the first metal pattern 52 and the capacitance between the second metal pattern 52 and the ground layer 70 (second capacitance) within the design target range, The balance of the differential line can be increased.

  At this time, adjusting the difference between the first capacity and the second capacity to be within the range of the design target includes adjusting the first capacity and the second capacity equally. By such adjustment, the balance of the differential line can be increased. The same applies to the description of the second embodiment.

  From here, first, the area of the first metal pattern 51 is the same as or larger than the total area of the first connection conductor 21 and the first component 31, and the area of the second metal pattern 52 is the second. A case where the connecting conductor 22 and the second component 32 are the same or larger than the total area will be described.

  As described above, the first connection conductor 21 and the first component 31 are arranged in the area of the first metal pattern 51, and the second connection conductor 22 and the second component 32 are formed of the second metal pattern. When arranged in the area, electrostatic capacitance (first capacitance) generated between the first metal pattern 51 and the ground layer 70 and static electricity generated between the second metal pattern 52 and the ground layer 70. By adjusting the difference from the electric capacity (second capacity) to be within the range of the design target, the balance of the differential line can be increased.

  At this time, as adjustment targets, the area of the first metal pattern 51, the distance between the first metal pattern 51 and the ground layer 70, the area of the second metal pattern 52, the second metal pattern 52, and the ground layer are included. The distance between 70 is mentioned.

  Subsequently, if the area of the first metal pattern 51 is smaller than the combined area of the first connection conductor 21 and the first component 31, all of at least one of the first connection conductor 21 and the first component 31 are included. Alternatively, if a part is disposed outside the area of the first metal pattern 51 and the area of the second metal pattern 52 is smaller than the combined area of the second connection conductor 22 and the second component 32, the first All or a part of at least one of the two connection conductors 22 and the second component 32 may be disposed outside the area of the second metal pattern 52.

  For example, when at least a part of the first connection conductor 21 and the first component 31 is disposed outside the area of the first metal pattern 51, the portion between the portion disposed outside the area and the ground layer 70 is disposed. The electrostatic capacity generated in the step 1 is generated in addition to the electrostatic capacity generated between the first metal pattern 51 and the ground 70. Further, for example, when at least a part of the second connection conductor 22 and the second component 32 is disposed outside the area of the second metal pattern 52, the portion disposed outside the area and the ground layer 70. The capacitance generated between the second metal pattern 52 and the ground 70 is generated in addition to the capacitance generated between the second metal pattern 52 and the ground 70.

  First, the area of the first metal pattern 51 is smaller than the combined area of the first connection conductor 21 and the first component 31, and the area of the second metal pattern 52 is the second connection conductor 22 and the second connection pattern. A case where the area is smaller than the combined area of the parts 32 will be described.

  In this way, at least one part of the first connection conductor 21 and the first component 31 is disposed outside the area of the first metal pattern 51, and the second connection conductor 22 and the second component are arranged. 32 is arranged outside the area of the first metal pattern 51 in the first connection conductor 21 and the first component 31 when at least a part of the second metal pattern 52 is arranged outside the area of the second metal pattern 52. A combined capacitance (first capacitance) of the capacitance generated between the formed portion and the ground layer 70 and the capacitance generated between the first metal pattern 51 and the ground layer 70, and the second connection A capacitance generated between a portion of the conductor 22 and the second component 32 arranged outside the area of the second metal pattern 52 and the ground layer 70, and between the second metal pattern 52 and the ground layer 70. The static that occurs in By the difference between the combined capacitance of the capacitor (second capacitor) is adjusted to be within the design target, it is possible to increase the balance of the differential lines.

  At this time, as an object of adjustment, the area of the first metal pattern 51, the distance between the first metal pattern 51 and the ground layer 70, the first metal in the first connection conductor 21 and the first component 31 are used. The area of the portion arranged outside the area of the pattern 51, the distance between the portion arranged outside the area and the ground layer 70, the area of the second metal pattern 52, and between the second metal pattern 52 and the ground layer 70 The distance, the area of the portion of the second connecting conductor 22 and the second component 32 that are disposed outside the area of the second metal pattern 52, and the distance between the portion disposed outside the area and the ground layer 70 are listed. It is done.

  Next, the area of the first metal pattern 51 is the same or larger than the total area of the first connection conductor 21 and the first component 31, and the area of the second metal pattern 52 is the second connection conductor 22. A case where the area is smaller than the combined area of the second component 32 will be described.

  As described above, the first connection conductor 21 and the first component 31 are arranged in the area of the first metal pattern 51, and at least one of the second connection conductor 22 and the second component 32. When the portion is disposed outside the area of the second metal pattern 52, the capacitance (first capacitance) generated between the first metal pattern 51 and the ground layer 70, the second connection conductor 22 and The electrostatic capacitance generated between the portion of the second part 32 arranged outside the area of the second metal pattern 52 and the ground layer 70 and the static electricity generated between the second metal pattern 52 and the ground layer 70. By adjusting the difference between the capacitance and the combined capacitance (second capacitance) to be within the design target range, the balance of the differential line can be increased.

  At this time, as adjustment targets, the area of the first metal pattern 51, the distance between the first metal pattern 51 and the ground layer 70, the area of the second metal pattern 52, the second metal pattern 52, and the ground layer are included. 70, the area of the portion of the second connecting conductor 22 and the second component 32 that is disposed outside the area of the second metal pattern 52, and the portion that is disposed outside the area and the ground layer 70. Distance.

  The first conductor and the related first component, the first connecting conductor, the first metal pattern, the second conductor and the related second component, and the second connection described so far. For the conductor and the second metal pattern, for example, even if the interpretation of the relationship between the arrangement of the first and second metal patterns and the size of the area is reversed, the difference is similarly adjusted by adjusting according to the condition contents. The balance of the line can be increased.

  The metal pattern shape and via arrangement in the second embodiment can be explained in the same manner as the metal pattern shape and via arrangement in the first embodiment shown in FIG. 2, and a plurality of layers are electrically connected. be able to.

  In the second embodiment, a pair of first component 31, second component 32, first connection conductor 21, first connection conductor 21 with respect to the first conductor 11 and the second conductor 21 forming the differential line. The mounting of the two connection conductors 22, the first metal pattern 51, and the second metal pattern 52 has been described. There may be cases where multiple wirings or other parts are mounted on this printed circuit board, or connection conductors or parts may be mounted only on one side of the differential line. The overall balance can be increased by improving the balance.

  In the second embodiment, the printed circuit board having a four-layer structure has been described. However, the printed circuit board is not limited to the four layers and includes other layers not directly used in the mounting portion described here. It can also be applied to.

  As described above, according to the second embodiment of the present invention, the first component, the first connection conductor, the second component with respect to the first conductor and the second conductor forming the differential line, The first metal pattern and the second metal pattern are formed in different layers between the layer on which the second connection conductor is mounted and the ground layer, and the difference in capacitance between both sides of the differential line is within the design target range. Therefore, by increasing the balance of the differential line, common mode noise on the differential line is suppressed, radiation noise from the differential line is suppressed, and the resistance of the differential line is improved. Noise characteristics can be improved.

Embodiment 3 FIG.
A printed circuit board according to Embodiment 3 of the present invention will be described.

  4 is a block diagram showing an example of a printed circuit board according to Embodiment 3 of the present invention. 4A is a schematic plan view of the printed circuit board, and FIG. 4B is a schematic cross-sectional view taken along the line CC in FIG. 4A.

  In the figure, a printed circuit board 1 has a layer for mounting wiring and components and a ground layer. The first conductor 11 and the second conductor 12 form a differential line formed in a layer for mounting wiring and components. The first component 31 and the second component 32 are placed at positions close to each other with the differential line interposed therebetween. The first connection conductor 21 connects the first component 31 and the first conductor 11. The second connection conductor 22 connects the second component 32 and the second conductor 12. The first metal pattern 51 is formed at a position directly below the first connection conductor 21 and the first component 31 in a layer between the wiring and component mounting layers and the ground layer. The second metal pattern 52 is formed at a position directly below the second connection conductor 22 and the second component 32 in a layer different from the layer on which the first metal pattern 51 is formed across the ground layer. The first via 41 electrically connects the first conductor 11 and the first metal pattern 51. The second via 42 electrically connects the second conductor 12 and the second metal pattern 52.

  Thus, the printed circuit board 1 includes the first conductor 11, the second conductor 12, the first component 31, the second component 32, the first connection conductor 21, and the first conductor 11 as layers for mounting wiring and components. A first layer in which two connection conductors 22 are disposed, a second layer in which the first metal pattern 51 is formed, a third layer in which the ground 70 is disposed as a ground layer, and a second metal pattern 52 has a multi-layer structure composed of a fourth layer, the first via 41 is between the first layer and the second layer, and the second via 42 is the first layer and the fourth layer. Electrical connection between layers. At this time, the second via 42 is prevented from being in electrical contact with the ground layer 70.

  Here, when the 1st connection conductor 21 and the 1st component 31 are arrange | positioned in the area of the 1st metal pattern 51, the electrostatic capacitance between the ground layers 70 in the connection point of the 1st connection conductor 21 is carried out. The capacitance depends on the area of the first metal pattern 51 and the distance between the first metal pattern 51 and the ground layer 70.

  The capacitance between the second connection conductor 22 and the ground layer 70 at the connection point is equal to the capacitance between the second connection conductor 22 and the second component 32 and the ground layer 70, and the second capacitance. The resultant capacitance is a capacitance between the metal pattern 52 and the ground layer 70. At this time, the electrostatic capacitance between the second connection conductor 22 and the second component 32 and the ground layer 70 is equal to the area of the second connection conductor 22 and the second component 32, and the connection conductor 22 and the component 32. And the distance between the ground layer 70 and the ground layer 70. Further, the capacitance between the second metal pattern 52 and the ground layer 70 depends on the area of the second metal pattern 52 and the distance between the second metal pattern 52 and the ground layer 70.

  For example, as shown in FIG. 4A, when the first connection conductor 21 is larger than the second connection conductor 22, the balance of the differential line deteriorates, but the area of the first metal pattern 51, The area of the second connection conductor 22 and the component 32, the area of the second metal pattern 52, the distance between the first metal pattern 51 and the ground layer 70, the second connection conductor 22 and the second component 32 The capacitance between the first metal pattern 51 and the ground layer 70 (first capacitance) is adjusted by adjusting the distance between the first metal pattern 51 and the ground layer 70. The difference between the capacitance between the connection conductor 22 and the component 32 and the ground layer 70 and the combined capacitance (second capacitance) of the capacitance between the second metal pattern 52 and the ground layer 70 is within the design target range. The balance of the differential line Can Kusuru.

  At this time, adjusting the difference between the first capacity and the second capacity to be within the range of the design target includes adjusting the first capacity and the second capacity equally. By such adjustment, the balance of the differential line can be increased. The same applies to the description of the third embodiment.

  From here, first, the case where the area of the first metal pattern 51 is the same or larger than the combined area of the first connection conductor 21 and the first component 31 will be described.

  As described above, when the first connection conductor 21 and the first component 31 are arranged in the area of the first metal pattern 51, the capacitance generated between the first metal pattern 51 and the ground layer 70. (First capacitance), capacitance generated between the second connection conductor 22 and the ground plane layer 70, capacitance generated between the second component 32 and the ground layer 70, and the second metal. The balance of the differential line is increased by adjusting the difference between the combined capacitance (second capacitance) of the electrostatic capacitance generated between the pattern 52 and the ground layer 70 to be within the design target range. be able to.

  At this time, as an object of adjustment, the area of the first metal pattern 51, the distance between the first metal pattern 51 and the ground layer 70, the area of the second connection conductor 22 and the second component 32, and the second Examples include the area of the metal pattern 52, the distance between the second connection conductor 22 and the ground layer 70, the distance between the second component 32 and the ground layer 70, and the distance between the second metal pattern 52 and the ground layer 70.

  Subsequently, if the area of the first metal pattern 51 is smaller than the combined area of the first connection conductor 21 and the first component 31, all of at least one of the first connection conductor 21 and the first component 31 are included. Or a part may be arrange | positioned outside the area of the 1st metal pattern 51. FIG.

  For example, when at least a part of the first connection conductor 21 and the first component 31 is disposed outside the area of the first metal pattern 51, the portion between the portion disposed outside the area and the ground layer 70 is disposed. The electrostatic capacity generated in the step 1 is generated in addition to the electrostatic capacity generated between the first metal pattern 51 and the ground 70.

  First, a case where the area of the first metal pattern 51 is smaller than the combined area of the first connection conductor 21 and the first component 31 will be described.

  As described above, when a part of at least one of the first connection conductor 21 and the first component 31 is disposed outside the area of the first metal pattern 51, the first connection conductor 21 and the first component Capacitance generated between the part 31 and the portion disposed outside the area of the first metal pattern 51 and the ground layer 70, and capacitance generated between the first metal pattern 51 and the ground layer 70 A combined capacitance (first capacitance), a capacitance generated between the second connection conductor 22 and the ground plane layer 70, a capacitance generated between the second component 32 and the ground layer 70, and a first capacitance The balance of the differential line is adjusted by adjusting the difference between the combined capacitance (second capacitance) of the electrostatic capacitance generated between the second metal pattern 52 and the ground layer 70 within the design target range. Can be high.

  At this time, as an object of adjustment, the area of the first metal pattern 51, the distance between the first metal pattern 51 and the ground layer 70, the first metal in the first connection conductor 21 and the first component 31 are used. The area of the portion arranged outside the area of the pattern 51, the distance between the portion arranged outside the area and the ground layer 70, the area of the second connection conductor 22 and the second component 32, and the second metal pattern 52 And the distance between the second connection conductor 22 and the ground layer 70, the distance between the second component 32 and the ground layer 70, and the distance between the second metal pattern 52 and the ground layer 70.

  As a modified example, when the first metal pattern 51 is formed in the same layer as the second metal pattern 52 that is separated from the ground layer 70, the first metal pattern 51 is formed between the first connection conductor 21 and the ground plane layer 70. The first capacitance is the combined capacitance of the capacitance generated between the first component 31 and the ground layer 70 and the capacitance generated between the first metal pattern 51 and the ground layer 70. As a result, the balance of the differential line can be increased by adjusting the difference between the first capacitance and the second capacitance to be within the range of the design target.

  The first conductor and the related first component, the first connecting conductor, the first metal pattern, the second conductor and the related second component, and the second connection described so far. For the conductor and the second metal pattern, for example, even if the interpretation of the relationship between the arrangement of the first and second metal patterns and the size of the area is reversed, the difference is similarly adjusted by adjusting according to the condition contents. The balance of the line can be increased.

  The metal pattern shape and via arrangement in the third embodiment can also be explained in the same manner as the metal pattern shape and via arrangement in the first embodiment shown in FIG. 2, and a plurality of layers are electrically connected. be able to.

  In the third embodiment, a pair of first component 31, second component 32, first connection conductor 21, first connection conductor 21 with respect to the first conductor 11 and the second conductor 21 forming the differential line. The mounting of the two connection conductors 22, the first metal pattern 51, and the second metal pattern 52 has been described. There may be cases where multiple wirings or other parts are mounted on this printed circuit board, or connection conductors or parts may be mounted only on one side of the differential line. The overall balance can be increased by improving the balance.

  In the third embodiment, the mounting is described for a printed circuit board having a four-layer structure. However, the printed circuit board is not limited to four layers, and includes other layers not directly used in the mounting portion described here. It can also be applied to.

  As described above, according to the third embodiment of the present invention, the first component, the first connection conductor, the second component with respect to the first conductor and the second conductor forming the differential line, The first metal pattern is formed on a different layer between the layer on which the second connection conductor is mounted and the ground layer, and the second metal pattern is formed on a different layer across the ground layer. Is adjusted to be within the range of the design target. By increasing the balance of the differential line, common mode noise on the differential line is suppressed and radiation noise from the differential line is suppressed. In addition, the noise resistance of the differential line can be improved.

Embodiment 4 FIG.
A printed circuit board according to Embodiment 4 of the present invention will be described.

  FIG. 5 is a block diagram showing an example of a printed circuit board according to Embodiment 4 of the present invention. 5A is a schematic plan view of the printed circuit board, and FIG. 5B is a schematic cross-sectional view taken along the line DD in FIG. 5A.

  In the figure, a printed circuit board 1 has a layer for mounting wiring and components and a ground layer. The first conductor 11 and the second conductor 12 form a differential line formed in a layer for mounting wiring and components. The first component 31 and the second component 32 are placed at positions close to each other with the differential line interposed therebetween. The first connection conductor 21 connects the first component 31 and the first conductor 11. The second connection conductor 22 connects the second component 32 and the second conductor 12.

  Here, the impedance between the first connection conductor 21 and the ground layer 70 depends on the capacitance between the first connection conductor 21 and the first component 31 and the ground layer 70.

  Similarly, the impedance between the second connection conductor 22 and the ground layer 70 depends on the capacitance between the second connection conductor 22 and the second component 32 and the ground layer 70.

  Therefore, by making the combined area of the first connecting conductor 21 and the first component 31 equal to the combined area of the second connecting conductor 22 and the second component 32, or the difference between these two areas By making it within the design target range, the balance of the differential line can be increased.

  In the fourth embodiment, a pair of first component 31, second component 32, first connection conductor 21, first connection conductor 21, second conductor 21 with respect to the first conductor 11 and the second conductor 21 constituting the differential line. The mounting of the two connection conductors 22 has been described. There may be cases where multiple wirings or other parts are mounted on this printed circuit board, or connection conductors or parts may be mounted only on one side of the differential line. The overall balance can be increased by improving the balance.

  Further, in the fourth embodiment, the mounting is described for the printed circuit board having a two-layer structure in which the number of layers is smaller than that in the first to third embodiments. The present invention can also be applied to a printed circuit board having a multilayer structure including other layers not used.

  As described above, according to the fourth embodiment of the present invention, the first conductor and the second conductor are formed on the first conductor and the second conductor that form the differential line. The parts, the first connection conductor, the second part, and the second connection conductor are mounted, and the area of the first connection conductor and the first part is combined with the second connection conductor and the second part. Since the difference of the measured area is adjusted to be within the range of the design target, the common mode noise on the differential line is suppressed by increasing the balance of the differential line, and the difference from the differential line While suppressing radiation noise, the noise resistance of the differential line can be improved.

Embodiment 5. FIG.
A printed circuit board according to Embodiment 5 of the present invention will be described.

  6 is a block diagram showing an example of a printed circuit board according to Embodiment 5 of the present invention. 6A is a schematic plan view of the printed circuit board, and FIG. 6B is a schematic cross-sectional view taken along the line EE in FIG. 6A.

  In the figure, a printed circuit board 1 has a layer for mounting wiring and components and a ground layer. The first conductor 11 and the second conductor 12 form a differential line formed in a layer for mounting wiring and components. The first connection conductor 21 is connected to the first conductor 11. The second connection conductor 22 is connected to the second conductor 12. The first component 31 is placed on the first connection conductor 21 with the first insulator 61 interposed therebetween. The second component 32 is placed on the second connection conductor 22 with the second insulator 62 interposed therebetween.

  Here, the impedance between the first connection conductor 21 and the ground layer 70 depends only on the area of the first connection conductor 21.

  Similarly, the impedance between the second connection conductor 22 and the ground layer 70 depends only on the area of the second connection conductor 22.

  Therefore, by making the area of the first connection conductor 21 and the area of the second connection conductor 22 equal, or by making the difference between these two areas within the design target range, the balance of the differential line Can be high.

  In the fifth embodiment, a pair of first component 31, second component 32, first connection conductor 21, first connection conductor 21 with respect to the first conductor 11 and the second conductor 21 forming the differential line. The mounting of the two connection conductors 22 has been described. There may be cases where multiple wirings or other parts are mounted on this printed circuit board, or connection conductors or parts may be mounted only on one side of the differential line. The overall balance can be increased by improving the balance.

  Further, in the fifth embodiment, the mounting is described for the printed circuit board having a two-layer structure in which the number of layers is smaller than that in the first to third embodiments. The present invention can also be applied to a printed circuit board having a multilayer structure including other layers not used.

  As described above, according to the fifth embodiment of the present invention, the first conductor and the second conductor are formed on the first conductor and the second conductor which form the differential line. The first component is mounted on the connection conductor and the second component is mounted on the second connection conductor, and the difference between the area of the first connection conductor and the area of the second connection conductor is within the design target range. Therefore, by increasing the balance of the differential line, common mode noise on the differential line is suppressed, radiation noise from the differential line is suppressed, and the resistance of the differential line is improved. Noise characteristics can be improved.

Embodiment 6 FIG.
A printed circuit board according to Embodiment 6 of the present invention will be described.

  FIG. 7 is a block diagram showing an example of a printed circuit board according to Embodiment 6 of the present invention. 7A is a schematic plan view of the printed circuit board, and FIG. 7B is a schematic cross-sectional view taken along the line FF in FIG. 7A.

  In the figure, the printed circuit board 1 has a ground layer and a layer for mounting wiring and a layer for mounting components. The first conductor 11 and the second conductor 12 form a differential line formed in a layer for mounting wiring. The first component 31 and the second component 32 are placed directly below a position adjacent to the differential line. The first connection conductor 21 is connected to the first component 31 and is formed up to a position directly below the first conductor 11. It is connected to the second connection conductor 22 and is formed up to a position immediately below the second conductor 12. The first metal pattern 51 is formed at a position directly above the first connection conductor 21 and the first component 31 in a layer between the layer on which the component is mounted and the ground layer. The second metal pattern 52 is formed at a position immediately above the second connection conductor 22 and the second component 32 in a layer between the layer on which the component is mounted and the ground layer. The first via 41 electrically connects the first conductor 11, the first metal pattern 51, and the first connection conductor 21. The second via 42 electrically connects the second conductor 12, the second metal pattern 52, and the second connection conductor 22.

  Thus, the printed circuit board 1 includes a first layer in which the first conductor 11 and the second conductor 12 are disposed as a layer for mounting wiring, and a second layer in which the ground 70 is disposed as a ground layer. The first layer 31, the second component 32, the first connection conductor 21, the third layer on which the first metal pattern 51 and the second metal pattern 52 are formed, and the layer on which the component is mounted. The first via 41 and the second via 42 are electrically connected between the first layer, the third layer, and the fourth layer. Connect to. At this time, the first via 41 and the second via 42 are prevented from being in electrical contact with the ground layer 70.

  Here, when the first connection conductor 21 and the first component 31 are arranged in the area of the first metal pattern 51, the impedance between the first connection conductor 21 and the ground layer 70 is the first metal. It depends only on the area of the pattern 51.

  Similarly, when the second connection conductor 22 and the second component 32 are disposed in the area of the second metal pattern 52, the impedance between the second connection conductor 22 and the ground layer 70 is the second metal. It depends only on the area of the pattern 52.

For example, as shown in FIG. 7A, when the first connection conductor 21 is larger than the second connection conductor 22, the balance of the differential line deteriorates, but the area of the first metal pattern 51 and By making the difference in the area of the second metal pattern 52 within the range of the design target, the balance of the differential line can be increased.
That is, an electrostatic capacity (first capacity) generated between the first metal pattern 51 and the ground layer 70 and an electrostatic capacity (second capacity) generated between the second metal pattern 52 and the ground layer 70. ) Within the range of the design target, the balance of the differential line can be increased.

  At this time, adjusting the difference between the first capacity and the second capacity to be within the range of the design target includes adjusting the first capacity and the second capacity equally. By such adjustment, the balance of the differential line can be increased. The same applies to the description of the sixth embodiment.

  From here, first, the area of the first metal pattern 51 is the same as or larger than the total area of the first connection conductor 21 and the first component 31, and the area of the second metal pattern 52 is the second. A case where the connecting conductor 22 and the second component 32 are the same or larger than the total area will be described.

  As described above, the first connection conductor 21 and the first component 31 are arranged in the area of the first metal pattern 51, and the second connection conductor 22 and the second component 32 are formed of the second metal pattern. When arranged in the area, electrostatic capacitance (first capacitance) generated between the first metal pattern 51 and the ground layer 70 and static electricity generated between the second metal pattern 52 and the ground layer 70. By adjusting the difference from the electric capacity (second capacity) to be within the range of the design target, the balance of the differential line can be increased.

  At this time, examples of the adjustment target include the area of the first metal pattern 51 and the area of the second metal pattern 52.

  Subsequently, if the area of the first metal pattern 51 is smaller than the combined area of the first connection conductor 21 and the first component 31, all of at least one of the first connection conductor 21 and the first component 31 are included. Alternatively, if a part is disposed outside the area of the first metal pattern 51 and the area of the second metal pattern 52 is smaller than the combined area of the second connection conductor 22 and the second component 32, the first All or a part of at least one of the two connection conductors 22 and the second component 32 may be disposed outside the area of the second metal pattern 52.

  For example, when at least a part of the first connection conductor 21 and the first component 31 is disposed outside the area of the first metal pattern 51, the portion between the portion disposed outside the area and the ground layer 70 is disposed. The electrostatic capacity generated in the step 1 is generated in addition to the electrostatic capacity generated between the first metal pattern 51 and the ground 70. Further, for example, when at least a part of the second connection conductor 22 and the second component 32 is disposed outside the area of the second metal pattern 52, the portion disposed outside the area and the ground layer 70. The capacitance generated between the second metal pattern 52 and the ground 70 is generated in addition to the capacitance generated between the second metal pattern 52 and the ground 70.

  First, the area of the first metal pattern 51 is smaller than the combined area of the first connection conductor 21 and the first component 31, and the area of the second metal pattern 52 is the second connection conductor 22 and the second connection pattern. A case where the area is smaller than the combined area of the parts 32 will be described.

  In this way, at least one part of the first connection conductor 21 and the first component 31 is disposed outside the area of the first metal pattern 51, and the second connection conductor 22 and the second component are arranged. 32 is arranged outside the area of the first metal pattern 51 in the first connection conductor 21 and the first component 31 when at least a part of the second metal pattern 52 is arranged outside the area of the second metal pattern 52. A combined capacitance (first capacitance) of the capacitance generated between the formed portion and the ground layer 70 and the capacitance generated between the first metal pattern 51 and the ground layer 70, and the second connection A capacitance generated between a portion of the conductor 22 and the second component 32 arranged outside the area of the second metal pattern 52 and the ground layer 70, and between the second metal pattern 52 and the ground layer 70. The static that occurs in By the difference between the combined capacitance of the capacitor (second capacitor) is adjusted to be within the design target, it is possible to increase the balance of the differential lines.

  At this time, as an object of adjustment, the area of the first metal pattern 51, the area of the first connecting conductor 21 and the first component 31 arranged outside the area of the first metal pattern 51, and the area The distance between the portion arranged outside the area and the ground layer 70, the area of the second metal pattern 52, and the second connection conductor 22 and the second component 32 are arranged outside the area of the second metal pattern 52. And the distance between the portion disposed outside the area and the ground layer 70.

  Next, the area of the first metal pattern 51 is the same or larger than the total area of the first connection conductor 21 and the first component 31, and the area of the second metal pattern 52 is the second connection conductor 22. A case where the area is smaller than the combined area of the second component 32 will be described.

  As described above, the first connection conductor 21 and the first component 31 are arranged in the area of the first metal pattern 51, and at least one of the second connection conductor 22 and the second component 32. When the portion is disposed outside the area of the second metal pattern 52, the capacitance (first capacitance) generated between the first metal pattern 51 and the ground layer 70, the second connection conductor 22 and The electrostatic capacitance generated between the portion of the second part 32 arranged outside the area of the second metal pattern 52 and the ground layer 70 and the static electricity generated between the second metal pattern 52 and the ground layer 70. By adjusting the difference between the capacitance and the combined capacitance (second capacitance) to be within the design target range, the balance of the differential line can be increased.

  At this time, as the adjustment target, the area of the first metal pattern 51 and the area of the second metal pattern 52 and the area outside the second metal pattern 52 in the second connection conductor 22 and the second component 32 are included. And the distance between the portion disposed outside the area and the ground layer 70.

  The first conductor and the related first component, the first connecting conductor, the first metal pattern, the second conductor and the related second component, and the second connection described so far. For the conductor and the second metal pattern, for example, even if the interpretation of the relationship between the arrangement of the first and second metal patterns and the size of the area is reversed, the difference is similarly adjusted by adjusting according to the condition contents. The balance of the line can be increased.

  Regarding the shape of the metal pattern and the arrangement of the vias in the sixth embodiment, for example, since the connection conductors 21 and 22 are arranged up to just below the conductors 11 and 12 to connect the vias 41 and 42, FIG. , (B) can be described in the same manner as the metal pattern shape and via arrangement in the first embodiment, and a plurality of layers can be electrically connected.

  In the sixth embodiment, the first and second metal patterns are formed in the same layer. However, they may be formed in different layers as in the second embodiment, and as in the third embodiment. It may be formed in different layers with the GULAND layer in between.

  When the layers are formed in different layers as in the second embodiment, the capacitance (first capacitance) generated between the first metal pattern 51 and the ground layer 70, the second metal pattern 52, and the ground layer. 70, the area of the first metal pattern 51 and the distance between the first metal pattern 51 and the ground layer 70 so that the difference from the capacitance (second capacitance) generated between the first metal pattern 51 and the ground layer 70 is within the range of the design target. The distance, the area of the second metal pattern 52, and the distance between the second metal pattern 52 and the ground layer 70 are adjusted. When at least a part of the component or the connection conductor is disposed outside the area of the metal pattern, the combined capacitance may be adjusted as described in the second embodiment.

  In the case where the ground layer is formed in a different layer as in the third embodiment, the electrostatic capacitance (first capacitance) generated between the first metal pattern 51 and the ground layer 70 and the second Between the second metal pattern 52 and the ground layer 70, and between the second metal pattern 52 and the ground layer 70. The area of the first metal pattern 51 and the distance between the first metal pattern 51 and the ground layer 70 so that the difference between the generated capacitance and the combined capacitance (second capacitance) is within the design target range. The area of the second metal pattern 52, the distance between the second connection conductor 22, the second component 32, and the ground layer 70 and the distance between the second metal pattern 52 and the ground layer 70 are adjusted. When at least a part of the first component 31 or the first connection conductor 21 is disposed outside the area of the first metal pattern 51, the composite capacitance is adjusted as described in the third embodiment. Good.

  In the sixth embodiment, a pair of first component 31, second component 32, first connection conductor 21, first connection conductor 21 with respect to the first conductor 11 and the second conductor 21 forming the differential line. The mounting of the two connection conductors 22, the first metal pattern 51, and the second metal pattern 52 has been described. There may be cases where multiple wirings or other parts are mounted on this printed circuit board, or connection conductors or parts may be mounted only on one side of the differential line. The overall balance can be increased by improving the balance.

  In the sixth embodiment, mounting is described for a printed circuit board having a four-layer structure. However, the printed circuit board is not limited to four layers and includes other layers not directly used in the mounting portion described here. It can also be applied to.

  As described above, according to the sixth embodiment of the present invention, the first conductor and the second conductor are mounted on the first conductor and the second conductor forming the differential line, and the first conductor and the second conductor are mounted on the first conductor and the second conductor. The layer for mounting the component, the first connection conductor, the second component, and the second connection conductor is formed across the ground layer, and the first component, the first connection conductor, the second component, the second component, The first metal pattern and the second metal pattern are formed on the same layer or different layers between the layer on which the two connection conductors are mounted and the ground layer, and the difference in capacitance between both sides of the differential line is within the design target range. Since the adjustment is made so as to be inside, the balance of the differential line can be increased.

  According to the sixth embodiment of the present invention, the first conductor, the layer on which the second conductor is mounted, and the first component with respect to the first conductor and the second conductor forming the differential line, A layer for mounting the first connection conductor, the second component, and the second connection conductor is formed across the ground layer, and the layer between the first conductor and the layer for mounting the second conductor and the ground layer is formed. Since the first metal pattern and the second metal pattern are formed on the same layer or different layers and the difference in capacitance between both sides of the differential line is adjusted within the design target range, the differential line By increasing the degree of balance, the common mode noise on the differential line can be suppressed, radiation noise from the differential line can be suppressed, and the noise resistance of the differential line can be improved.

  Depending on mounting, these embodiments may be combined and mounted.

  As described above, according to the embodiment of the present invention, when a component is connected to a differential line, a design is performed in which the capacitance is adjusted by each conductor of the differential line, and the metal facing the ground layer The difference in capacitance between the differential lines generated between the ground layers in the pattern, connecting conductors and parts is adjusted within the design target range. It is possible to suppress common mode noise on the line, suppress radiation noise from the differential line, and improve the noise resistance of the differential line.

  DESCRIPTION OF SYMBOLS 1 Digital signal transmission board | substrate, 2 1st conductor, 2nd conductor, 4 island-like conductor, 5 metal foil, 6 capacitive stub, 10 printed circuit board, 11 1st conductor, 12 2nd conductor, 21 1st connection conductor, 22 2nd connection conductor, 31 1st component, 32 2nd component, 41 1st via, 42 2nd via, 51 1st metal pattern, 52 2nd metal pattern , 60 dielectric, 61 first insulator, 62 second insulator, 70 ground layer.

Claims (9)

In a printed circuit board having a layer for mounting wiring and components and a ground layer,
A differential line composed of a first conductor and a second conductor formed in a layer for mounting the wiring and components;
A first part and a second part placed between the differential lines,
A first connection conductor connecting the first component and the first conductor;
A second connection conductor connecting the second component and the second conductor;
In a layer between the wiring and component mounting layer and the ground layer,
A first metal pattern formed at a position immediately below the first connection conductor and the first component and electrically connected to the first conductor or the first connection conductor ;
A second metal pattern formed at a position directly below the second connection conductor and the second component and electrically connected to the second conductor or the second connection conductor ;
The first connection conductor and the first component are arranged in the area of the first metal pattern, and the second connection conductor and the second component are in the area of the second metal pattern. A first capacitance that is disposed between the first metal pattern and the ground layer, and a capacitance that is generated between the second metal pattern and the ground layer. The difference in the second capacity is within the design target range.
A printed circuit board characterized by that . The first metal pattern and the second metal pattern are formed in the same layer;
The printed circuit board according to claim 1 , wherein a difference between an area of the first metal pattern and an area of the second metal pattern is within a design target range. In a printed circuit board having a ground layer, a layer for sandwiching the ground layer and a layer for mounting wiring and a layer for mounting components,
A differential line composed of a first conductor and a second conductor formed in a layer for mounting the wiring;
A first component and a second component placed on a layer on which the component is mounted immediately below the differential line;
A first connection conductor connecting the first component and a position directly below the first conductor;
A second connection conductor connecting the second component and a position directly below the second conductor;
In a layer between the component mounting layer and the ground layer,
A first metal pattern formed at a position immediately above the first connection conductor and the first component;
A second metal pattern formed at a position directly above the second connection conductor and the second component;
A printed circuit in which the first conductor, the first metal pattern, the first connection conductor, the second conductor, the second metal pattern, and the second connection conductor are electrically connected to each other. substrate. The first connection conductor and the first component are arranged in the area of the first metal pattern, and the second connection conductor and the second component are in the area of the second metal pattern. If placed
A first capacitance that is a capacitance generated between the first metal pattern and the ground layer, and a second capacitance that is a capacitance generated between the second metal pattern and the ground layer. The printed circuit board according to claim 3, wherein the difference is within a design target range. A part of at least one of the first connection conductor and the first component is disposed outside the area of the first metal pattern, and at least in the second connection conductor and the second component. When any part is disposed outside the area of the second metal pattern,
Capacitance generated between a portion of the first connection conductor and the first component arranged outside the area of the first metal pattern and the ground layer, the first metal pattern, and the ground A first capacitance which is a combined capacitance with an electrostatic capacitance generated between the layer and a portion of the second connection conductor and the second component which are disposed outside the area of the second metal pattern; and The difference between the second capacitance, which is a combined capacitance of the capacitance generated between the ground layer and the capacitance generated between the second metal pattern and the ground layer, is within a design target range. Item 4. The printed circuit board according to item 3 . The first connection conductor and the first component are disposed in an area of the first metal pattern, and at least a part of the second connection conductor and the second component is the first component. When placed outside the area of the metal pattern of 2,
Arranged outside the area of the second metal pattern in the first capacitor, the second connection conductor and the second component, which is a capacitance generated between the first metal pattern and the ground layer. The difference between the second capacitance, which is the combined capacitance of the capacitance generated between the formed portion and the ground layer and the capacitance generated between the second metal pattern and the ground layer, is the design target. The printed circuit board according to claim 3 , which is within a range. The printed circuit board according to claim 3, wherein the first metal pattern and the second metal pattern are formed in the same layer. The printed circuit board according to any one of claims 3 to 6 wherein the first metal pattern and the second metal pattern is formed on another layer. The printed circuit board according to claim 8, wherein the first metal pattern and the second metal pattern are formed in the other layer with the ground layer interposed therebetween.

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