CN210840178U - Circuit board for reducing differential line insertion loss - Google Patents
Circuit board for reducing differential line insertion loss Download PDFInfo
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- CN210840178U CN210840178U CN201921129818.8U CN201921129818U CN210840178U CN 210840178 U CN210840178 U CN 210840178U CN 201921129818 U CN201921129818 U CN 201921129818U CN 210840178 U CN210840178 U CN 210840178U
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Abstract
The utility model relates to a reduce difference line insertion loss's circuit board, including the carrier. One side surface of the carrier is provided with a first grounding layer, and the other side surface of the carrier is provided with a first circuit layer. The carrier is also provided with a plurality of first grounding holes. The first line layer includes a first differential line. The first grounding holes are sequentially arranged at intervals along the first differential lines, and the conducting layer on the inner side wall of each first grounding hole is electrically connected with the first grounding layer. According to the circuit board for reducing the insertion loss of the differential lines, the plurality of first grounding holes are arranged at intervals on the side parts of the first differential lines, so that when current flows through the first differential lines, a magnetic field is formed, reflected signals exist among the wires, and the signal reflection can be reduced by the first grounding holes; in addition, the coupling effect is stronger when the distance between the first differential lines is smaller, and the coupling effect of the coupling magnetic field can be relieved by the first grounding holes at the side parts of the first differential lines, so that the insertion loss of signals is reduced, the signal transmission is stable, and the fluctuation is small.
Description
Technical Field
The utility model relates to a circuit board preparation technical field especially relates to a reduce circuit board of difference line insertion loss.
Background
In PCB design and manufacture, the impact of many factors negligible in conventional circuits on PCB signal integrity is increasingly manifested. The differential line of the traditional circuit board can be arranged on the surface layer circuit of the circuit board, namely a microstrip line when the differential line is arranged on the surface layer circuit of the circuit board, can also be arranged on the inner layer circuit of the circuit board, namely a strip line when the differential line is arranged on the inner layer circuit of the circuit board. Wherein, there is transmission loss on the differential line, and the existence of the transmission loss will result in lower signal transmission quality.
Disclosure of Invention
Therefore, it is necessary to overcome the defects of the prior art and provide a circuit board capable of reducing the insertion loss of the differential line of the PCB, which has smooth signal transmission and small fluctuation.
The technical scheme is as follows: a wiring board for reducing differential line insertion loss, comprising: the carrier, one of them side of carrier is equipped with first ground plane, the another side of carrier is equipped with first circuit layer, still be equipped with the first ground hole of a plurality of on the carrier, first circuit layer includes first difference line, first ground hole along first difference line interval arrangement in proper order, the conducting layer of the inside wall in first ground hole with first ground plane electric connection.
According to the circuit board for reducing the insertion loss of the differential lines, the plurality of first grounding holes are arranged at intervals on the side parts of the first differential lines, so that when current flows through the first differential lines, a magnetic field is formed, reflected signals exist among the wires, and the first grounding holes can play a role in reducing reflection; in addition, the signal lines are usually designed as differential lines, the coupling effect is stronger when the distance between the first differential lines is smaller, and the coupling effect of the coupling magnetic field is reduced by the first grounding holes at the side parts of the first differential lines, so that the insertion loss of the signal is reduced, the signal transmission is stable, and the fluctuation is small.
In one embodiment, a plurality of first grounding holes are arranged at intervals on two sides of the first differential line.
In one embodiment, the distance d between two adjacent first grounding holes on the same side of the first differential line satisfies: 20mil ≦ d ≦ 24 mil.
In one embodiment, the distance L between the first grounding hole and the first differential line satisfies: l < 9mil < 11 mil.
In one embodiment, the carrier is a base material, and the first ground hole is filled with a resin.
In one embodiment, the aperture D1 of the first grounding hole is controlled to be 0.3mm < D1 < 0.8 mm.
In one embodiment, the circuit board for reducing differential line insertion loss further includes a first prepreg, a second ground layer, and a second circuit layer; the first semi-cured sheet is laid on the first circuit layer, the second grounding layer is laid on the first semi-cured sheet, a plurality of second grounding holes are arranged on the first semi-cured sheet at intervals along the first differential line, and the conducting layers of the second grounding holes are electrically connected with the conducting layers of the first grounding holes or the second grounding layer; the second prepreg is laid above the first grounding layer, the second circuit layer is laid on the second prepreg, the second circuit layer comprises a second differential line, a plurality of third grounding holes are arranged on the second prepreg at intervals along the second differential line, and the conducting layers of the third grounding holes are electrically connected with the first grounding layer.
In one embodiment, the circuit board for reducing differential line insertion loss further includes a third prepreg, a fourth prepreg, and a third circuit layer, the third prepreg is disposed on the second ground layer, the third prepreg is provided with a fourth ground hole, the fourth ground hole is electrically connected to the second ground layer, the third circuit layer is disposed on the third prepreg, the third circuit layer includes a third differential line, and the fourth ground hole is disposed at intervals along the second differential line; the fourth prepreg is laid on the second circuit layer, a plurality of fifth grounding holes are formed in the fourth prepreg at intervals along the second differential line, and the conducting layers of the fifth grounding holes are electrically connected with the conducting layers of the third grounding holes.
In one embodiment, the second grounding hole, the third grounding hole, the fourth grounding hole and the fifth grounding hole are all laser drilled holes, and the inner side walls of the laser drilled holes are filled with copper; the aperture D2 of the second grounding hole, the third grounding hole, the fourth grounding hole and the fifth grounding hole is controlled to be 0.1mm ≦ D2 ≦ 0.2 mm.
In one embodiment, the circuit board for reducing differential line insertion loss further includes a reinforcing copper layer disposed on the fourth prepreg.
Drawings
Fig. 1 is a simplified diagram of a circuit board for reducing differential line insertion loss according to an embodiment of the present invention;
fig. 2 is a structural diagram of a circuit board for reducing differential line insertion loss according to another embodiment of the present invention;
fig. 3 is a graph illustrating insertion loss corresponding to different frequency signals introduced into a differential line on a circuit board for reducing insertion loss of the differential line according to an embodiment of the present invention.
Reference numerals:
10. carrier, 11, first ground via, 20, first ground plane, 31, first differential line, 40, first prepreg, 41, second ground via, 50, second prepreg, 51, third ground via, 60, second ground plane, 71, second differential line, 80, third prepreg, 81, fourth ground via, 90, fourth prepreg, 91, fifth ground via, 101, third differential line, 110, reinforced copper layer, 120, antipad.
Detailed Description
In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments of the present invention are described in detail below with reference to the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, as those skilled in the art will be able to make similar modifications without departing from the spirit and scope of the present invention.
In the description of the present invention, it is to be understood that the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.
In the description of the present invention, it is to be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. In contrast, when an element is referred to as being "directly connected" to another element, there are no intervening elements present.
In one embodiment, referring to fig. 1 and 2, a circuit board for reducing differential line insertion loss includes a carrier 10. One side surface of the carrier 10 is provided with a first ground plane 20, and the other side surface of the carrier 10 is provided with a first circuit layer. The carrier 10 is further provided with a plurality of first grounding holes 11. The first line layer includes a first differential line 31. The first grounding holes 11 are sequentially arranged along the first differential lines 31 at intervals, and the conductive layer on the inner side wall of the first grounding hole 11 is electrically connected with the first grounding layer 20.
In the circuit board for reducing the insertion loss of the differential lines, because the plurality of first grounding holes 11 are arranged at intervals on the side part of the first differential line 31, when current flows on the first differential line 31, a magnetic field is formed, reflected signals exist among the wires, and the first grounding holes 11 can play a role in reducing reflection; in addition, the signal lines are usually designed as differential lines, the coupling effect is stronger when the distance between the first differential lines 31 is smaller, and the first grounding hole 11 at the side of the first differential line 31 can reduce the coupling effect of the coupling magnetic field, thereby reducing the insertion loss of the signal, and enabling the signal transmission to be smooth and the fluctuation to be small.
Further, a plurality of first grounding holes 11 are arranged at intervals on both sides of the first differential line 31. Therefore, the reflection effect of the signal can be favorably reduced, the insertion loss of the signal can be reduced, and the signal transmission is stable.
In one embodiment, the distance d between two adjacent first grounding holes 11 on the same side of the first differential line 31 satisfies: 20mil ≦ d ≦ 24 mil. Therefore, on one hand, the distance between the adjacent first grounding holes 11 is not too large, which is beneficial to reducing the reflection of signals and simultaneously reducing the insertion loss of the signals, so that the signals are transmitted stably; on the other hand, the distance between the adjacent first grounding holes 11 is not too small, so that electromagnetic influence caused by the too small distance can be avoided.
In one embodiment, the spacing L between the first ground via 11 and the first differential line 31 satisfies: l < 9mil < 11 mil. Therefore, on one hand, the distance L between the first grounding hole 11 and the first differential line 31 is not too large, which is beneficial to reducing the reflection of the signal and simultaneously reducing the insertion loss of the signal, so that the signal transmission is stable; on the other hand, the distance L between the first ground via 11 and the first differential line 31 is not too small, and the electromagnetic influence caused by the too small distance can be avoided.
In one embodiment, referring to fig. 2, the carrier 10 is a substrate, and the first grounding hole 11 is filled with resin. As an alternative, the carrier 10 may also be a prepreg, and the first grounding hole 11 is formed by laser drilling and copper plating on the prepreg.
Further, the aperture diameter D1 of the first grounding hole 11 is controlled to be 0.3mm ≦ D1 ≦ 0.8 mm.
In one embodiment, the circuit board for reducing differential line insertion loss further includes a first prepreg 40, a second prepreg 50, a second ground layer 60, and a second circuit layer. The first semi-cured sheet 40 is laid on the first circuit layer, the second ground layer 60 is laid on the first semi-cured sheet 40, a plurality of second ground holes 41 are arranged on the first semi-cured sheet 40 at intervals along the first differential line 31, and a conductive layer of each second ground hole 41 is electrically connected with a conductive layer of the first ground hole 11 or the second ground layer 60. Therefore, the second grounding hole 41 can further reduce the reflected signal of the first differential line 31, slow down the coupling effect of the coupling magnetic field of the first differential line 31, reduce the insertion loss of the signal, and enable the signal transmission to be smooth and small in fluctuation.
In addition, the second prepreg 50 is laid above the first ground layer 20, the second circuit layer is laid on the second prepreg 50, the second circuit layer includes a second differential line 71, a plurality of third ground holes 51 are arranged on the second prepreg 50 at intervals along the second differential line 71, and a conductive layer of the third ground holes 51 is electrically connected to the first ground layer 20. Similar to the first differential line 31, the third grounding hole 51 can reduce the reflected signal of the second differential line 71, slow down the coupling effect of the coupling magnetic field of the second differential line 71, and reduce the insertion loss of the signal, so that the signal transmission is smooth and the fluctuation is small.
In one embodiment, the circuit board for reducing differential line insertion loss further includes a third prepreg 80, a fourth prepreg 90, and a third circuit layer. The third prepreg 80 is laid on the second ground layer 60, and a fourth ground hole 81 is formed in the third prepreg 80. The fourth grounding hole 81 is electrically connected to the second grounding layer 60, the third circuit layer is laid on the third prepreg 80, the third circuit layer includes a third differential line 101, and the fourth grounding hole 81 is arranged along the second differential line 71 at intervals. The fourth prepreg 90 is laid on the second circuit layer, a plurality of fifth grounding holes 91 are formed in the fourth prepreg 90 at intervals along the second differential line 71, and the conductive layers of the fifth grounding holes 91 are electrically connected with the conductive layers of the third grounding holes 51.
In one embodiment, the second grounding hole 41, the third grounding hole 51, the fourth grounding hole 81 and the fifth grounding hole 91 are all laser drilled holes, and the inner side walls of the laser drilled holes are filled with copper, so that an open circuit caused by the fact that residual liquid medicine enters the laser drilled holes and etches away the copper can be avoided. Specifically, the aperture D2 of the second grounding hole 41, the third grounding hole 51, the fourth grounding hole 81, and the fifth grounding hole 91 is controlled to be, for example, 0.1mm ≦ D2 ≦ 0.2mm, and the aperture is small, so that the space is saved, more space can be made for other lines, and the product volume is reduced.
In one embodiment, the circuit board for reducing differential line insertion loss further includes a reinforcing copper layer 110 disposed on the fourth prepreg 90. The reinforcing copper layer 110 can enhance the structural strength of the circuit board for reducing the differential line insertion loss, and can prevent the board from being stressed and bent.
In the above embodiments, the first grounding hole 11, the second grounding hole 41, the third grounding hole 51, the fourth grounding hole 81 and the fifth grounding hole 91 are not electrically connected to the circuit layer, so that the first grounding hole 11, the second grounding hole 41, the third grounding hole 51, the fourth grounding hole 81 and the fifth grounding hole 91 directly transmit signals to the corresponding grounding layer without transmitting signals to the circuit layer. Specifically, the first circuit layer is provided with an anti-pad 120 circumferentially arranged around the first ground hole 11, and the anti-pad 120 isolates the first circuit layer from the conductive layer of the first ground hole 11. Similarly, the first wiring layer is provided with anti-lands 120 arranged circumferentially around the second ground hole 41. Since the first ground hole 11 and the second ground hole 41 are stacked in the vertical direction, the anti-pad 120 around the first ground hole 11 and the anti-pad 120 around the second ground hole 41 are the same.
Further, the second wiring layer is provided with the anti-lands 120 circumferentially arranged around the third ground hole 51, and with the anti-lands 120 circumferentially arranged around the fifth ground hole 91. Since the third ground hole 51 and the fifth ground hole 91 are stacked in the vertical direction, the anti-pad 120 around the third ground hole 51 and the anti-pad 120 around the fifth ground hole 91 are the same.
In addition, the third wiring layer is provided with anti-lands 120 arranged axially around the fourth grounding hole 81.
Further, when the system capacity is lower than 3Gbps, only media, namely raw materials used for manufacturing the PCB, are used as process factors influencing the signal transmission loss of the PCB, and low-Df plates and ink are used for reducing the insertion loss of differential lines of the PCB; when the system capacity is increased to 5Gbps, the line width of the transmission line manufactured by the actual process becomes an influencing factor, the line width consistency is ensured, and the line width precision is controlled to reduce the insertion loss of the PCB differential line; when the system capacity is increased to lOGbps, the roughness of the copper foil influences the loss of signal transmission, the surface treatment of the outer layer of the substrate changes the roughness of the surface of the microstrip line to cause the difference of transmission loss, and meanwhile, the length of the back drilling Stub (Stub) becomes a factor influencing the characteristic impedance of the transmission line, so that on one hand, the surface roughness of the line is reduced: a low roughness copper foil (HVLP series) is used, a low roughness pretreatment mode is adopted for manufacturing, on the other hand, the Stub length is controlled, and the shorter the Stub length is, the smaller the insertion loss of a PCB differential line is; when the system capacity is increased to 17Gbps, the copper thickness influences the performance and the loss of the transmission line, and the extreme difference of the copper thickness is controlled to reduce the insertion loss of a differential line of the PCB; when the system capacity is increased to 20Gbps +, the surface roughness of the strip transmission line is affected by the surface treatment of the inner layer of the substrate, so that the difference of transmission loss is caused, and the insertion loss of the differential line of the PCB is reduced by selecting the low-roughness brown chemical liquid.
In the above embodiment, the differential lines of the circuit board for reducing the insertion loss of the differential lines are fed with signals of different frequencies to obtain the corresponding insertion loss when the signals of different frequencies are obtained, and the differential lines of the conventional circuit board are fed with signals of different frequencies to obtain the corresponding insertion loss when the signals of different frequencies are also obtained. The different frequency signals and corresponding insertion losses are recorded in the following data table, and a graph 3 is drawn according to the different frequency signals and corresponding insertion losses.
| Frequency (GHZ) | 4 | 6 | 8 | 10 | 12.9 |
| With earth hole | -0.329 | -0.39 | -0.493 | -0.607 | -0.741 |
| Without ground hole | -0.273 | -0.435 | -0.507 | -0.62 | -0.78 |
| Frequency (GHZ) | 14 | 16 | 18 | 20 | |
| With earth hole | -0.795 | -0.887 | -0.974 | -1.02 | |
| Without ground hole | -0.895 | -0.976 | -0.983 | -1.084 |
According to the data table and the graph 3, it can be found that the loss can be reduced by about 0.04dB/inch by adding the grounding hole at the side part of the differential line. Secondly, the signal transmission is more stable without large fluctuation.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.
Claims (10)
1. A circuit board for reducing differential line insertion loss, comprising:
the carrier, one of them side of carrier is equipped with first ground plane, the another side of carrier is equipped with first circuit layer, still be equipped with the first ground hole of a plurality of on the carrier, first circuit layer includes first difference line, first ground hole along first difference line interval arrangement in proper order, the conducting layer of the inside wall in first ground hole with first ground plane electric connection.
2. The circuit board for reducing insertion loss of differential lines according to claim 1, wherein a plurality of first grounding holes are arranged at intervals on both sides of the first differential line.
3. The circuit board according to claim 1, wherein the distance d between two adjacent first grounding holes on the same side of the first differential line satisfies: 20mil ≦ d ≦ 24 mil.
4. The circuit board for reducing insertion loss of differential lines according to claim 1, wherein a distance L between the first grounding hole and the first differential line satisfies: l < 9mil < 11 mil.
5. A circuit board for reducing differential line insertion loss according to any one of claims 1 to 4, wherein the carrier is a base material, and the first grounding hole is filled with resin.
6. The circuit board of claim 5, wherein the aperture D1 of the first ground via is controlled to be 0.3mm < D1 < 0.8 mm.
7. The wiring board for reducing differential line insertion loss according to claim 5, further comprising a first prepreg, a second ground layer, and a second wiring layer; the first semi-cured sheet is laid on the first circuit layer, the second grounding layer is laid on the first semi-cured sheet, a plurality of second grounding holes are arranged on the first semi-cured sheet at intervals along the first differential line, and the conducting layers of the second grounding holes are electrically connected with the conducting layers of the first grounding holes or the second grounding layer;
the second prepreg is laid above the first grounding layer, the second circuit layer is laid on the second prepreg, the second circuit layer comprises a second differential line, a plurality of third grounding holes are arranged on the second prepreg at intervals along the second differential line, and the conducting layers of the third grounding holes are electrically connected with the first grounding layer.
8. The circuit board according to claim 7, further comprising a third prepreg, a fourth prepreg and a third circuit layer, wherein the third prepreg is disposed on the second ground layer, the third prepreg is provided with a fourth ground hole thereon, the fourth ground hole is electrically connected to the second ground layer, the third circuit layer is disposed on the third prepreg, the third circuit layer includes a third differential line, and the fourth ground hole is disposed at intervals along the second differential line; the fourth prepreg is laid on the second circuit layer, a plurality of fifth grounding holes are formed in the fourth prepreg at intervals along the second differential line, and the conducting layers of the fifth grounding holes are electrically connected with the conducting layers of the third grounding holes.
9. The circuit board of claim 8, wherein the second ground via, the third ground via, the fourth ground via, and the fifth ground via are all laser drilled holes, and the inner sidewalls of the laser drilled holes are filled with copper; the aperture D2 of the second grounding hole, the third grounding hole, the fourth grounding hole and the fifth grounding hole is controlled to be 0.1mm ≦ D2 ≦ 0.2 mm.
10. The wiring board for reducing differential line insertion loss according to claim 8, further comprising a reinforcing copper layer disposed on said fourth prepreg.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921129818.8U CN210840178U (en) | 2019-07-18 | 2019-07-18 | Circuit board for reducing differential line insertion loss |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201921129818.8U CN210840178U (en) | 2019-07-18 | 2019-07-18 | Circuit board for reducing differential line insertion loss |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN210840178U true CN210840178U (en) | 2020-06-23 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201921129818.8U Active CN210840178U (en) | 2019-07-18 | 2019-07-18 | Circuit board for reducing differential line insertion loss |
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| CN (1) | CN210840178U (en) |
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