Printed circuit board and electronic equipment
By placing isolated metal components on the multilayer board of the printed circuit board, especially in the middle area between signal vias, the mutual capacitance between differential lines is increased, the impedance jump problem of differential traces at via locations is solved, the inductive jump during layer switching is optimized, and the impedance uniformity is improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-26
- Publication Date
- 2026-03-27
AI Technical Summary
Differential traces on printed circuit boards exhibit impedance jumps at via locations, and inductive jumps are particularly difficult to control during layer transitions.
By placing isolated metal components on the multilayer board of the printed circuit board, especially in the middle area between signal vias, the mutual capacitance between differential lines can be increased, thereby reducing the inductive jump of differential impedance.
By setting isolated metal components, the impedance uniformity of differential traces during layer switching was optimized, the inductive jump at the signal via location was reduced, and the overall impedance uniformity of the differential channel was improved.
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Figure CN121751470A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of circuit boards, in particular to a printed circuit board and an electronic device. BACKGROUND
[0002] A printed circuit board (PCB) is an important structure for physical support and signal transmission of an electronic device, and a via is one of common structures of the printed circuit board. After a multi-layer board of the printed circuit board is pressed, a via is formed by drilling through the multi-layer board by a mechanical drill bit and then electroplating a conductive layer, and the via is used for connecting lines in the printed circuit board in a vertical direction when the lines change layers.
[0003] A differential line is a signal transmission mode, which involves two lines of equal length, equal width, close to each other and on the same layer. The purpose of this wiring mode is to transmit a differential signal, that is, two signals of equal amplitude but opposite phase.
[0004] When designing a differential line on a printed circuit board, the design goal of differential impedance needs to be ensured as consistent as possible at all positions of the line, but the differential line generally needs to change layers, and punching is necessarily involved in changing layers. There is usually impedance jump at the position of the via. In related designs, the capacitance and inductance of the via are adjusted by adjusting the avoidance distance of the via to the surrounding copper skin, so as to adjust the inductance on the reflow path and adjust the impedance of the via, but in actual application, the adjustment of the avoidance distance has limitations, for example, the line around the via is dense, and there is no extra space to increase the distance between the copper skin and the differential via. SUMMARY
[0005] The purpose of the present application is to provide a printed circuit board and an electronic device, and the structure of the printed circuit board can reduce the inductive jump of the differential impedance of the differential line at the signal via position, which is beneficial to optimizing the impedance uniformity performance of the whole differential channel.
[0006] To solve the above technical problems, the present application provides a printed circuit board, comprising a multi-layer board and a differential line.
[0007] The multi-layer board is provided with a signal via, and the signal via penetrates the multi-layer board.
[0008] The differential line comprises a first differential line and a second differential line, the first differential line and the second differential line are located on different layers, and the first differential line is electrically connected with the second differential line through a pair of signal vias.
[0009] A pair of signal vias comprises a first signal via and a second signal via, and at least one isolated metal piece is arranged between the first signal via and the second signal via.
[0010] In an implementable solution, the layer plate where the first differential line is located is provided with the isolated metal piece.
[0011] In an implementable solution, the layer plate where the second differential line is located is provided with the isolated metal piece.
[0012] In an implementable solution, both the layer plate where the first differential line is located and the layer plate where the second differential line is located are provided with the isolated metal piece.
[0013] In an implementable solution, at least one intermediate layer plate between the layer plate where the first differential line is located and the layer plate where the second differential line is located is provided with the isolated metal piece.
[0014] In an implementable solution, the isolated metal piece is located in a middle region between the first signal via and the second signal via.
[0015] In an implementable solution, the isolated metal piece is an isolated copper skin.
[0016] In an implementable solution, the isolated copper skin is formed on the substrate of the printed circuit board by etching.
[0017] In an implementable solution, at least one of the size, shape and arrangement position of the isolated copper skin is determined according to the distance between the first signal via and the second signal via and the distance between different layer plates of the printed circuit board.
[0018] The embodiments of the present application also provide an electronic device comprising the printed circuit board as described in any of the above.
[0019] The printed circuit board provided by the embodiments of the present application can be used in an electronic device. The printed circuit board is provided with an isolated metal piece between a pair of signal vias of a differential line. That is, the isolated metal piece arranged between the first signal via and the second signal via can increase the mutual capacitance between the pair of differential lines, thereby reducing the inductive jump of the differential impedance at the position of the signal via, and further optimizing the inductive jump of the differential line when changing layers, so that the impedance uniformity of the whole differential channel is better. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 FIG. 1 is a structural schematic diagram of a front view of a printed circuit board according to an embodiment of the present application;
[0021] Figure 2 FIG. 2 is a structural schematic diagram of a cross section along A-A direction of the printed circuit board shown in FIG. 1; Figure 1
[0022] FIG. 3 is a structural schematic diagram of a cross section along B-B direction of the printed circuit board shown in FIG. 1; Figure 3 Figure 1 FIG. 4 is a structural schematic diagram of a partial structure of a differential line of the printed circuit board shown in FIG. 1;
[0023] Figure 4 This is a cross-sectional schematic diagram of the printed circuit board in Embodiment 2 provided in this application;
[0024] Figure 5 This is a cross-sectional schematic diagram of the printed circuit board in Embodiment 3 provided in this application;
[0025] Figure 6 This is a cross-sectional schematic diagram of the printed circuit board in Embodiment 4 provided in this application;
[0026] Figure 7 This is a schematic diagram comparing the differential impedance curves of the same printed circuit board with differential traces with and without the addition of isolated metal components.
[0027] Explanation of reference numerals in the attached figures:
[0028] Top layer 11, bottom layer 12, middle layer 13, first signal via 141, second signal via 142, first pad 151, second pad 152, first differential line 161, second differential line 162, isolated metal part 17, anti-pad 18. Detailed Implementation
[0029] The ordinal numbers used in this article, such as first and second, are used to distinguish different parts with the same name and do not indicate a specific order or primary / secondary relationship.
[0030] To address the impedance jump issue at via locations when differential traces involve vias in printed circuit boards (PCBs), this application provides a PCB comprising a multilayer board and differential traces. The multilayer board includes signal vias that penetrate the multilayer board. The differential traces include a first differential line and a second differential line located on different layers. The first differential line is electrically connected to the second differential line through a pair of signal vias. The differential traces are routed in pairs; that is, there is a pair of first differential lines and a pair of second differential lines.
[0031] For ease of description, the pair of signal vias are referred to as the first signal via and the second signal via, and at least one isolated metal piece is provided between the first signal via and the second signal via.
[0032] There is no electrical or signal connection between the isolated metal parts here and the electrical components on the multilayer board.
[0033] By adopting the above scheme, the mutual capacitance between a pair of differential lines can be increased by using the isolated metal sheet placed between the first signal via and the second signal via. This reduces the inductive jump of the differential impedance at the signal via location, thereby optimizing the inductive jump of the differential trace when changing layers and making the impedance uniformity of the entire differential channel better.
[0034] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.
[0035] Please refer to Figures 1 to 3 , Figure 1 This is a schematic diagram of the structure of a printed circuit board from the front view of an embodiment provided in this application. Figure 2 for Figure 1 Schematic diagram of the cross section along the AA direction. Figure 3 for Figure 1 The diagram shows a partial structural schematic of the differential traces on the printed circuit board. Wherein, Figure 3 The middle section clearly illustrates the location of differential traces and isolated metal components, while the multi-layer board structure is omitted.
[0036] In this embodiment, the printed circuit board includes a multilayer board, which can be formed by lamination. The multilayer board includes a top layer board 11, a bottom layer board 12, and intermediate layers 13 located between the top layer board 11 and the bottom layer board 12. The number and thickness of the intermediate layers 13 can be set as needed, and the thickness of the top layer board 11 and the bottom layer board 12 can also be set as needed. In the illustrated example, the number of intermediate layers 13 is 8.
[0037] The printed circuit board also includes differential traces on a multilayer board. These differential traces include first differential lines 161 and second differential lines 162, which are located on different layers. It can be understood that differential lines are used to transmit differential signals, which are two signals with equal amplitude but opposite phase. Therefore, there is a pair of first differential lines 161, i.e., two first differential lines 161, and a pair of second differential lines 162, i.e., two second differential lines 162.
[0038] The multilayer board has signal vias that penetrate the multilayer board. For example, after the multilayer board is laminated, the signal vias can be formed by drilling through the board with a mechanical drill bit and then electroplating conductive material.
[0039] The following example illustrates the arrangement of differential traces, with the first differential line 161 and the second differential line 162 located on the top layer board 11 and the bottom layer board 12, respectively. The two first differential lines 161 are respectively connected to the two second differential lines 162 through a pair of signal vias.
[0040] For ease of description, the two signal vias included in a pair of signal vias are referred to as the first signal via 141 and the second signal via 142, respectively.
[0041] Both the first signal via 141 and the second signal via 142 have a first pad 151 on the top layer plate 11, and both have a second pad 152 on the bottom layer plate 12. A first differential line 161 is electrically connected to the first signal via 141 through the first pad 151, and a second differential line 162 is electrically connected to the first signal via 141 through the second pad 152, thus achieving electrical connection between the first differential line 161 and the second differential line 162. The other first differential line 161 and the other second differential line 162 are electrically connected in the same way.
[0042] Figure 2 In the illustrated embodiment, an isolated metal element 17 is provided on the layer where the first differential line 161 is located, that is, an isolated metal element 17 is provided on the top layer 11, and this isolated metal element 17 is also located in the anti-pad area of the top layer 11. Anti-pad refers to the hollowed-out area around the signal via in the layer structure of the printed circuit board.
[0043] With the above settings, the mutual capacitance between the first differential line 161 and the second differential line 162 can be increased by using the isolated metal part 17 set on the top plate 11, thereby reducing the inductive jump of the differential impedance at the signal via location, and thus optimizing the inductive jump of the differential trace when changing layers, resulting in better impedance uniformity of the entire differential channel.
[0044] In practice, the isolated metal component 17 can be made of copper foil, meaning that the isolated metal component 17 is an isolated copper foil. This isolated copper foil can be formed by etching using the existing circuit structure of the printed circuit board substrate. This method is simple to operate and makes it easy to ensure the position of the isolated copper foil.
[0045] In the illustrated example, the isolated metal part 17 has a rectangular shape. In other embodiments, the isolated metal part 17 may also have a circular, elliptical, or polygonal shape, etc.
[0046] In the specific implementation, the isolated metal component 17 is located in the middle region between the first signal via 141 and the second signal via 142. That is, the distance between the center of the isolated metal component 17 and the center of the first signal via 141 is approximately the same as the distance between the center of the isolated metal component 17 and the center of the second signal via 142, so as to minimize the inductive jump of differential blocking at the signal via location.
[0047] In other embodiments, the isolated metal part 17 may also be positioned close to the first signal via 141 or close to the second signal via 142, depending on the application requirements.
[0048] The size of the isolated metal part 17 can be set according to the actual application requirements.
[0049] The location of the isolated metal part 17, in addition toFigures 1 to 3 In addition to the layer where the first differential line 161 shown is located, it can also be set on other layers.
[0050] Please refer to Figure 4 , Figure 4 This is a cross-sectional schematic diagram of the printed circuit board in Embodiment 2 provided in this application.
[0051] Figure 4 In the illustrated embodiment, the printed circuit board includes a multilayer board, which can be formed by lamination. The multilayer board includes a top layer 11, a bottom layer 12, and intermediate layers 13 located between the top layer 11 and the bottom layer 12. The number and thickness of the intermediate layers 13 can be set as needed, and the thickness of the top layer 11 and the bottom layer 12 can also be set as needed. In the illustrated example, there are 8 intermediate layers 13.
[0052] The printed circuit board also includes differential traces on the multilayer board. The differential traces include a first differential line 161 and a second differential line 162, located on the top layer board 11 and the bottom layer board 12, respectively. The multilayer board has a first signal via 141 and a second signal via 142. Both the first signal via 141 and the second signal via 142 have a first pad 151 on the top layer board 11 and a second pad 152 on the bottom layer board 12. One first differential line 161 is electrically connected to the first signal via 141 through the first pad 151, and one second differential line 162 is electrically connected to the first signal via 141 through the second pad 152, thus achieving electrical connection between the first differential line 161 and the second differential line 162. The other first differential line 161 and the other second differential line 162 are electrically connected in the same manner.
[0053] An isolated metal component 17 is provided on the layer where the second differential line 162 is located, that is, an isolated metal component 17 is provided on the bottom layer 12, and this isolated metal component 17 is also located in the anti-pad area of the bottom layer 12. Anti-pad refers to the hollowed-out area around the signal via in the layer structure of the printed circuit board.
[0054] With the above settings, the isolated metal part 17 set on the bottom plate 12 can increase the mutual capacitance between the first differential line 161 and the second differential line 162, thereby reducing the inductive jump of the differential impedance at the signal via location, and thus optimizing the inductive jump of the differential trace when changing layers, resulting in better impedance uniformity of the entire differential channel.
[0055] In practice, the isolated metal component 17 can be made of copper foil, meaning that the isolated metal component 17 is an isolated copper foil. This isolated copper foil can be formed by etching using the existing circuit structure of the printed circuit board substrate. This method is simple to operate and makes it easy to ensure the position of the isolated copper foil.
[0056] The shape and size of the isolated metal part 17 can be set as needed.
[0057] Please refer to Figure 5 , Figure 5 This is a cross-sectional schematic diagram of the printed circuit board in Embodiment 3 provided in this application.
[0058] Figure 5 In the illustrated embodiment, the printed circuit board includes a multilayer board, which can be formed by lamination. The multilayer board includes a top layer 11, a bottom layer 12, and intermediate layers 13 located between the top layer 11 and the bottom layer 12. The number and thickness of the intermediate layers 13 can be set as needed, and the thickness of the top layer 11 and the bottom layer 12 can also be set as needed. In the illustrated example, there are 8 intermediate layers 13.
[0059] The printed circuit board also includes differential traces on the multilayer board. The differential traces include a first differential line 161 and a second differential line 162, located on the top layer board 11 and the bottom layer board 12, respectively. The multilayer board has a first signal via 141 and a second signal via 142. Both the first signal via 141 and the second signal via 142 have a first pad 151 on the top layer board 11 and a second pad 152 on the bottom layer board 12. One first differential line 161 is electrically connected to the first signal via 141 through the first pad 151, and one second differential line 162 is electrically connected to the first signal via 141 through the second pad 152, thus achieving electrical connection between the first differential line 161 and the second differential line 162. The other first differential line 161 and the other second differential line 162 are electrically connected in the same manner.
[0060] Isolated metal parts 17 are provided on both the layer where the first differential line 161 is located and the layer where the second differential line 162 is located, that is, isolated metal parts 17 are provided on both the top layer 11 and the bottom layer 12.
[0061] With the above settings, the isolated metal parts 17 set on the top plate 11 and the bottom plate 12 can increase the mutual compatibility between the first differential line 161 and the second differential line 162, thereby reducing the inductive jump of the differential impedance at the signal via location, and further optimizing the inductive jump of the differential trace when changing layers, resulting in better impedance uniformity of the entire differential channel.
[0062] In practice, the isolated metal component 17 can be made of copper foil, meaning that the isolated metal component 17 is an isolated copper foil. This isolated copper foil can be formed by etching using the existing circuit structure of the printed circuit board substrate. This method is simple to operate and makes it easy to ensure the position of the isolated copper foil.
[0063] The shape and size of the isolated metal part 17 can be set as needed.
[0064] Please refer to Figure 6 , Figure 6 This is a cross-sectional schematic diagram of the printed circuit board in Embodiment 4 provided in this application.
[0065] Figure 6 In the illustrated embodiment, the printed circuit board includes a multilayer board, which can be formed by lamination. The multilayer board includes a top layer 11, a bottom layer 12, and intermediate layers 13 located between the top layer 11 and the bottom layer 12. The number and thickness of the intermediate layers 13 can be set as needed, and the thickness of the top layer 11 and the bottom layer 12 can also be set as needed. In the illustrated example, there are 8 intermediate layers 13.
[0066] The printed circuit board also includes differential traces on the multilayer board. The differential traces include a first differential line 161 and a second differential line 162, located on the top layer board 11 and the bottom layer board 12, respectively. The multilayer board has a first signal via 141 and a second signal via 142. Both the first signal via 141 and the second signal via 142 have a first pad 151 on the top layer board 11 and a second pad 152 on the bottom layer board 12. One first differential line 161 is electrically connected to the first signal via 141 through the first pad 151, and one second differential line 162 is electrically connected to the first signal via 141 through the second pad 152, thus achieving electrical connection between the first differential line 161 and the second differential line 162. The other first differential line 161 and the other second differential line 162 are electrically connected in the same manner.
[0067] Isolated metal parts 17 are provided on both the layer where the first differential line 161 is located and the layer where the second differential line 162 is located. At the same time, isolated metal parts 17 are also provided on some of the eight intermediate layers 13. Specifically, isolated metal parts are provided on the second intermediate layer 13, the fourth intermediate layer 13 and the fifth intermediate layer 13 in the direction from the top layer 11 to the bottom layer 12.
[0068] With the above settings, the isolated metal parts 17 set on the top layer plate 11, the bottom layer plate 12, and the middle layer plate 13 can increase the mutual capacitance between the first differential line 161 and the second differential line 162, thereby reducing the inductive jump of the differential impedance at the signal via location, and further optimizing the inductive jump of the differential trace when changing layers, resulting in better impedance uniformity of the entire differential channel.
[0069] In practice, the isolated metal component 17 can be made of copper foil, meaning that the isolated metal component 17 is an isolated copper foil. This isolated copper foil can be formed by etching using the existing circuit structure of the printed circuit board substrate. This method is simple to operate and makes it easy to ensure the position of the isolated copper foil.
[0070] The shape and size of the isolated metal part 17 can be set as needed.
[0071] In one implementation, at least one of the size, shape, and location of the isolated metal part 17 can be determined based on the distance between the first signal via 141 and the second signal via 142 and the distance between different layers of the printed circuit board.
[0072] In applications, the size, shape, and placement of the isolated metal component 17 can be determined through simulation or experimental design. For example, given the structure of the printed circuit board and the differential traces, several different sizes of isolated metal components 17 can be determined based on the distance between the first signal via 141 and the second signal via 142, and the different layers of the printed circuit board. Finally, the specific size of the isolated metal component 17 is selected based on the condition that the differential blocking effect at the signal via location is relatively good.
[0073] In one application example, by employing the solution provided in this application, placing at least one isolated metal element 17 between a pair of signal vias on a printed circuit board effectively improves the inductive transition of the differential impedance at the via location. (See reference...) Figure 7 understand, Figure 7 This is a schematic diagram comparing the differential impedance curves of the same printed circuit board with differential traces with and without the addition of isolated metal components.
[0074] In this circuit board, isolated metal parts 17 are provided on both the top layer board 11 and the bottom layer board 12, and the resulting differential impedance curves are as follows: Figure 7 The red curve in the image.
[0075] Without the isolated metal component 17, at the location of the signal via, i.e. Figure 7 At position m2, a sensitive mutation occurs, such as Figure 7 The blue lines in the diagram illustrate this.
[0076] The comparison shows that after adding the isolated metal part 17, the absolute value of the differential impedance at the signal via location decreased from 106.9 ohms to 105.6 ohms. This demonstrates that placing the isolated metal part 17 between a pair of signal vias to increase mutual capacitance and reduce inductive impedance transitions is effective.
[0077] In addition to the printed circuit board described above, this application also provides an electronic device that includes the printed circuit board described in the foregoing embodiments, and has corresponding technical effects.
[0078] For example, the electronic device may be a server, switch, mobile phone, computer, or smart wearable device, etc.
[0079] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only for the purpose of helping to understand the method and core ideas of this application. It should be noted that those skilled in the art can make several improvements and modifications to this application without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of this application.
Claims
1. A printed circuit board, characterized in that, Including multilayer boards and differential traces; The multilayer board is provided with signal vias, and the signal vias penetrate the multilayer board; The differential trace includes a first differential line and a second differential line, the first differential line and the second differential line are located on different layers, and the first differential line is electrically connected to the second differential line through a pair of signal vias; The pair of signal vias includes a first signal via and a second signal via, and at least one isolated metal element is provided between the first signal via and the second signal via.
2. The printed circuit board according to claim 1, characterized in that, The isolated metal component is provided on the layer where the first differential line is located.
3. The printed circuit board according to claim 1, characterized in that, The isolated metal component is provided on the layer where the second differential line is located.
4. The printed circuit board according to claim 1, characterized in that, The isolated metal component is provided on both the layer where the first differential line is located and the layer where the second differential line is located.
5. The printed circuit board according to claim 1, characterized in that, The isolated metal piece is provided on at least one intermediate layer between the layer on which the first differential line is located and the layer on which the second differential line is located.
6. The printed circuit board according to claim 1, characterized in that, The isolated metal component is located in the middle region between the first signal via and the second signal via.
7. The printed circuit board according to any one of claims 1-6, characterized in that, The isolated metal component is an isolated copper sheet.
8. The printed circuit board according to claim 7, characterized in that, The isolated copper foil is formed on the substrate of the printed circuit board by etching.
9. The printed circuit board according to claim 7, characterized in that, At least one of the size, shape, and location of the isolated copper foil is determined based on the distance between the first signal via and the second signal via, and the distance between different layers of the printed circuit board.
10. An electronic device, characterized in that, Including the printed circuit board as described in any one of claims 1-9.