Stack unit for printed circuit board, and printed circuit board

Abstract

Embodiments of the present disclosure provide a stack unit for a printed circuit board, and a printed circuit board. The stack unit comprises a plurality of metal layers and a plurality of dielectric layers. The plurality of metal layers and the plurality of dielectric layers are alternately stacked in the thickness direction. The plurality of metal layers include a signal transmission layer and paired reference layers arranged on two sides of the signal transmission layer. At least one of the two dielectric layers adjacent to the signal transmission layer is arranged as a resin isolation layer. The dielectric layers on the sides of the paired reference layers opposite to the signal transmission layer are arranged as reinforcing layers, and each reinforcing layer comprises a substrate and a resin material arranged around the substrate. Thus, the signal transmission quality of the signal transmission layer can be improved, and the signal transmission layer can stably transmit high-speed and high-frequency signals.

Description

Lamination unit for printed circuit board and printed circuit board

[0001] This application claims priority to the Chinese invention patent application entitled “Stacking unit for printed circuit board and printed circuit board” and application number 202410405267.2 filed on April 3, 2024, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] Example embodiments of the present disclosure generally relate to the field of printed circuit boards, and more particularly, to a stacking unit for a printed circuit board and a printed circuit board. Background Art

[0003] Current printed circuit boards (PCBs) can ensure uniform and stable transmission quality when transmitting low-speed, low-frequency digital signals. However, with the increasing demand for high-speed signals, circuit designs for high-speed signal transmission on PCBs face even more severe signal integrity challenges.

[0004] Especially in large-scale equipment, high-speed signals have high wiring density, high trace density, and a large number of heavy circuit board components, which leads to many restrictions on PCB stacking design and difficulty in optimizing signal quality. Summary of the Invention

[0005] In a first aspect of the present disclosure, a stacking unit for a printed circuit board is provided. The stacking unit comprises: a plurality of metal layers and a plurality of dielectric layers, the plurality of metal layers and the plurality of dielectric layers being alternately stacked along a thickness direction, wherein the plurality of metal layers comprise a signal transmission layer and a pair of reference layers disposed on either side of the signal transmission layer; at least one of the two dielectric layers adjacent to the signal transmission layer comprises a resin isolation layer; and the dielectric layer on the side of the paired reference layers opposite the signal transmission layer comprises a reinforcement layer, the reinforcement layer comprising a base material and a resin material disposed around the base material.

[0006] In a second aspect of the present disclosure, a printed circuit board is provided, comprising: a plurality of stacking units provided according to the first aspect of the present disclosure, wherein the plurality of stacking units are stacked along a thickness direction.

[0007] It should be understood that the content described in this summary section is not intended to limit the key features or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements, wherein:

[0009] FIG1 illustrates a cross-sectional view of a printed circuit board according to some embodiments of the present disclosure;

[0010] FIG2 shows a schematic diagram of a signal transmission layer according to some embodiments of the present disclosure;

[0011] 3A and 3B are schematic diagrams respectively showing the arrangement relationship between a signal transmission layer and an adjacent dielectric layer according to some embodiments of the present disclosure; and

[0012] FIG4 shows a schematic diagram of the overall structure of a printed circuit board according to some embodiments of the present disclosure.

[0013] Explanation of reference numerals: 100 printed circuit board; 200 stacking unit; 210 signal transmission layer; 220 reference layer; 230 resin isolation layer; 240 reinforcement layer; 250 power supply layer; 260 structural layer; 300 reinforcement rib. DETAILED DESCRIPTION

[0014] The following describes embodiments of the present disclosure in more detail with reference to the accompanying drawings. Although certain embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be construed as limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the present disclosure are for illustrative purposes only and are not intended to limit the scope of protection of the present disclosure.

[0015] It should be noted that the titles of any section / subsection provided herein are not limiting. Various embodiments are described throughout this document, and any type of embodiment may be included under any section / subsection. Furthermore, the embodiments described in any section / subsection may be combined in any manner with any other embodiments described in the same section / subsection and / or in different sections / subsections.

[0016] In the description of the embodiments of the present disclosure, the term "including" and similar terms should be understood as open inclusion, that is, "including but not limited to". The term "based on" should be understood as "based at least in part on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The term "some embodiments" should be understood as "at least some embodiments". Other explicit and implicit definitions may be included below. The terms "first", "second", etc. may refer to different or the same objects. Other explicit and implicit definitions may be included below.

[0017] As briefly mentioned above, current printed circuit boards (PCBs) are not suitable for high-speed, high-frequency data transmission. Specifically, the dielectric layers of conventional PCBs consist of glass fiber cloth and resin. The glass fiber cloth serves as a skeleton, adding strength and support, while the resin fills the gaps between the glass fiber cloths to provide adhesion. The dielectric constant of the resin is generally around 2 to 3, while the dielectric constant of the glass fiber is around 6, resulting in a significant difference between the two. Therefore, for differential signal lines, if the differential line (D+) is distributed on the glass fiber bundles and the differential line (D-) is distributed in the gaps between the glass fiber bundles, this will cause different signal delays on the two differential lines, resulting in differential signal skew distortion. Skew distortion leads to an increase in common-mode voltage and a corresponding decrease in differential signal. The resulting AC common-mode effect becomes a source of crosstalk and electromagnetic interference in the system.

[0018] According to the embodiments of the present disclosure, a stacking unit for a printed circuit board and a printed circuit board including the stacking unit are proposed to solve or at least partially solve the above-mentioned problems and other potential problems existing in the traditional solutions. According to various embodiments of the present disclosure, by setting at least one of the two dielectric layers on both sides of the signal transmission layer as a resin isolation layer constructed of resin, the arrangement of the glass fiber cloth near the signal transmission layer can be reduced, thereby reducing the influence of the dielectric layer on the transmission quality of the signal transmission layer, thereby improving the signal quality transmitted by the signal transmission layer, so that the signal transmission layer can be applied to high-speed and high-frequency signal transmission. On the other hand, in order to ensure the overall strength of the printed circuit board under the premise of adding the resin isolation layer, the paired reference layers arranged on both sides of the signal transmission layer are further arranged with a reinforcement layer on the side opposite to the signal transmission layer. The reinforcement layer can make up for the strength loss of the resin isolation layer by mixing glass fibers inside the resin, thereby improving the reliability of the printed circuit board.

[0019] Figure 1 illustrates a cross-sectional view of a printed circuit board 100 according to some embodiments of the present disclosure. As shown in Figure 1 , the printed circuit board 100 generally includes a plurality of stacked units 200 stacked along a thickness direction T. The plurality of stacked units 200 can be arranged within a chassis of a device and connected to various electronic devices or electrical components within the chassis, thereby facilitating power supply or data transmission to the plurality of electronic devices and electrical components.

[0020] As shown in FIG1 , each stacked unit 200 includes multiple metal layers and multiple dielectric layers, which are alternately stacked along the thickness direction T. Specifically, the multiple metal layers are spaced apart by a predetermined distance along the thickness direction T and arranged parallel to each other. Some of the metal layers are suitable for supplying power or transmitting signals to electronic devices or electrical components coupled to the printed circuit board 100. Each of the multiple dielectric layers is arranged between adjacent metal layers and is suitable for providing skeletal support for the printed circuit board 100 and establishing insulation isolation between adjacent metal layers.

[0021] As shown in FIG1 , the plurality of metal layers include a signal transmission layer 210 and a pair of reference layers 220 disposed on both sides of the signal transmission layer 210. FIG2 shows a schematic diagram of the signal transmission layer 210 according to some embodiments of the present disclosure. As shown in FIG2 , in some embodiments, the metal in the reference layer 220 can be formed into signal lines of predetermined shape and thickness by etching, cutting, etc. These signal lines can be electrically connected to specific electrical devices and electrical components coupled to the printed circuit board 100 to transmit electrical signals to specific electronic devices or electrical components. For example, the signal transmission layer 210 can include pairs of differential signal lines, and the paired differential signal lines can transmit differential signals to the electronic device.

[0022] As shown in Figures 1 and 2, at least one of the two dielectric layers adjacent to the signal transmission layer 210 is a resin isolation layer 230. The resin isolation layer 230 is a solid layer formed by cross-linking and curing the resin. The resin isolation layer 230 can be placed between the signal transmission layer 210 and the reference layer 220 to secure the signal transmission layer 210. Furthermore, because the resin isolation layer 230 does not use glass fiber as a skeletal support, the uniformity of electrical properties (e.g., dielectric constant) throughout the resin isolation layer 230 is more uniform, thereby reducing interference with the signal transmission layer 210 and making the signals (e.g., differential signals) transmitted within the signal transmission layer 210 more stable. This enables the printed circuit board 100 to be used for high-speed and high-frequency signal transmission.

[0023] Figures 3A and 3B respectively illustrate schematic diagrams of the arrangement relationship between the signal transmission layer 210 and adjacent dielectric layers in some embodiments of the present disclosure. In some embodiments, as shown in Figure 3A , both dielectric layers adjacent to the signal transmission layer 210 are resin isolation layers 230, thereby significantly reducing the impact of glass fiber on signal transmission quality. In other embodiments, as shown in Figure 3B , one of the two dielectric layers adjacent to the signal transmission layer 210 is a resin isolation layer 230, and the other is a reinforcement layer 240 constructed from a base material and resin (the reinforcement layer 240 will be described in more detail below). The combination of the resin isolation layer 230 and the reinforcement layer 240 not only reduces the impact of the dielectric layer on the signal transmission quality of the signal transmission layer 210, but also maintains the strength of the printed circuit board 100 to a certain extent, thereby ensuring the durability of the printed circuit board 100. In alternative embodiments, users can flexibly select between the two arrangements based on signal rate and system margin, or combine the two arrangements in any appropriate manner to meet signal rate and / or printed circuit board 100 strength requirements.

[0024] Returning to Figure 1 , the dielectric layer on the side of the paired reference layer 220 opposite the signal transmission layer 210 is the reinforcement layer 240. As briefly mentioned above, the reinforcement layer 240 is a solid layer formed after curing, using a base material as a framework and a resin as a filler. Compared to the resin isolation layer 230, it has higher strength. By arranging the reinforcement layer 240 on the side of the paired reference layer 220 facing away from the signal transmission layer 210, the loss in strength of the printed circuit board 100 caused by the use of the resin isolation layer 230 can be compensated to a certain extent. Furthermore, because the reference layer 220 isolates electromagnetic waves, the arrangement of the glass fiber in the reinforcement layer 240 does not affect the normal transmission of signals in the signal transmission layer 210.

[0025] In some embodiments, the substrate may be glass fiber. The glass fiber includes a plurality of first glass fiber bundles extending along a first direction and a second glass fiber bundle extending along a second direction. The plurality of first glass fiber bundles and the plurality of second glass fiber bundles intersect with each other, thereby forming a mesh-like structure of the glass fiber, thereby increasing the strength of the glass fiber and, in turn, the structural strength of the printed circuit board 100. In some embodiments, the first direction and the second direction may have a predetermined angle therebetween. In some embodiments, the first direction and the second direction may be perpendicular to each other. In other embodiments, the first direction and the second direction may have an angle, such as 45°, 60°, or 75°, between them.

[0026] In some embodiments, the first direction and the second direction have a predetermined angle with the signal line in the signal transmission layer. For example, the first direction and the second direction are arranged perpendicular to each other, and the first direction and the second direction each have an angle of 45° with the extension direction of the signal line.

[0027] In some embodiments, the metal layer further includes a power layer 250, and two dielectric layers adjacent to the power layer 250 are arranged as a structural layer 260. Similar to the reinforcement layer 240, the structural layer 260 is constructed by mixing a base material and a resin material, thereby ensuring the overall structural strength of the printed circuit board 100.

[0028] In some embodiments, the arrangement density of the glass fibers in the reinforcement layer 240 is greater than the arrangement density of the glass fibers in the structural layer 260. For example, the spacing between the plurality of first glass fiber bundles extending along the first direction in the reinforcement layer 240 is smaller than the spacing between the plurality of first glass fiber bundles extending along the first direction in the structural layer 260, and / or the spacing between the plurality of second glass fiber bundles extending along the second direction in the reinforcement layer 240 is smaller than the spacing between the plurality of second glass fiber bundles extending along the second direction in the structural layer 260. The denser arrangement of the glass fibers in the reinforcement layer 240 not only improves the strength of the reinforcement layer 240 but also improves the uniformity of the electrical properties across the reinforcement layer 240, thereby further reducing the impact of the dielectric layer on the stability of the transmitted signal.

[0029] In some embodiments, the weight ratio of glass fiber to resin in the reinforcement layer 240 exceeds the weight ratio of glass fiber to resin in the structural layer 260. That is, more glass fiber is used in the reinforcement layer 240 to improve the strength, so that the reinforcement layer 240 can compensate for the strength loss of the resin isolation layer 230, making the overall mechanical strength of the printed circuit board 100 more uniform.

[0030] FIG4 illustrates a schematic diagram of the overall structure of a printed circuit board 100 according to some embodiments of the present disclosure. As shown in FIG4 , in some embodiments, the printed circuit board 100 further includes a reinforcing rib 300 . The reinforcing rib 300 is arranged on one side of the plurality of stacked units 200 along the thickness direction T, and the reinforcing rib 300 extends in a direction perpendicular to the thickness direction T. In some embodiments, the reinforcing rib 300 can be made of metal and can be secured to the stacked units 200 by, for example, bonding. The provision of the reinforcing rib 300 can enhance the overall strength of the printed circuit board 100. In some embodiments, the reinforcing rib 300 can also be coupled to the chassis of a device, thereby securing the printed circuit board 100 within the device chassis via the reinforcing rib 300 .

[0031] In some embodiments, the arrangement direction of the reinforcing ribs 300 may be a horizontal direction or a vertical direction perpendicular to the thickness direction T. In some other embodiments, the arrangement direction of the reinforcing ribs 300 may also include any appropriate curved direction. For example, the reinforcing ribs 300 may extend in a straight horizontal direction or a vertical direction, or may extend along a curve.

[0032] In some embodiments, there is at least one reinforcement layer 240 and / or at least one structural layer 260 between two adjacent signal transmission layers 210 along the thickness direction T. In this way, the situation of insufficient local strength inside the printed circuit board 100 due to the centralized arrangement of the resin isolation layer 230 can be avoided.

[0033] Embodiments of the present disclosure are also embodied in the following examples.

[0034] Example 1. A stacking unit for a printed circuit board, comprising: a plurality of metal layers and a plurality of dielectric layers, wherein the plurality of metal layers and the plurality of dielectric layers are alternately stacked in a thickness direction,

[0035] wherein the plurality of metal layers include a signal transmission layer and a pair of reference layers arranged on both sides of the signal transmission layer;

[0036] At least one of the two dielectric layers adjacent to the signal transmission layer comprises a resin isolation layer;

[0037] The dielectric layer on the side of the paired reference layers opposite to the signal transmission layer includes a reinforcement layer, and the reinforcement layer includes a base material and a resin material arranged around the base material.

[0038] Example 2. The stacked unit according to Example 1, wherein one of the two dielectric layers adjacent to the signal transmission layer includes the resin isolation layer, and the other dielectric layer includes the reinforcement layer.

[0039] Example 3. The stacked unit according to Example 2, wherein the plurality of metal layers further comprises a power layer, and the two dielectric layers adjacent to the power layer comprise a structural layer, wherein the structural layer comprises a substrate and a resin material arranged around the substrate.

[0040] Example 4. A stacking unit according to Example 3, wherein the substrate in the reinforcing layer and the structural layer includes glass fibers, the glass fibers including a plurality of first glass fiber bundles extending along a first direction and a plurality of second glass fiber bundles extending along a second direction, the plurality of first glass fiber bundles intersecting the plurality of second glass fiber bundles so that the glass fibers form a mesh structure.

[0041] Example 5. The stacking unit according to Example 4, wherein the first direction or the second direction has a predetermined angle with an extension direction of the signal line in the signal transmission layer.

[0042] Example 6. The laminate unit of Example 4 or 5, wherein the arrangement density of the glass fibers in the reinforcing layer exceeds the arrangement density of the glass fibers in the structural layer.

[0043] Example 7. The laminate unit of example 4 or 5, wherein the weight ratio of glass fiber to resin in the reinforcement layer exceeds the weight ratio of glass fiber to resin in the structural layer.

[0044] Example 8. The stacking unit according to Example 3, wherein at least one reinforcement layer and / or at least one structural layer is arranged between two signal transmission layers adjacent to each other in the thickness direction.

[0045] Example 9. A printed circuit board, comprising a plurality of stacking units according to any one of Examples 1-8, wherein the plurality of stacking units are stacked along the thickness direction.

[0046] Example 10. The printed circuit board according to Example 9 further includes a reinforcing rib arranged on at least one side of the plurality of stacking units along the thickness direction and arranged to extend along an arrangement direction perpendicular to the thickness direction.

[0047] While various implementations of the present disclosure have been described above, the foregoing description is intended to be illustrative, not exhaustive, and not limited to the disclosed implementations. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described implementations. The terminology used herein is selected to best explain the principles of the implementations, their practical applications, or improvements to existing technologies, or to enable others skilled in the art to understand the various implementations disclosed herein.

Claims

1. A lamination unit (200) for a printed circuit board (100), comprising: A plurality of metal layers and a plurality of dielectric layers, wherein the plurality of metal layers and the plurality of dielectric layers are alternately stacked along a thickness direction (T), The plurality of metal layers include a signal transmission layer (210) and a pair of reference layers (220) arranged on both sides of the signal transmission layer (210); At least one of the two dielectric layers adjacent to the signal transmission layer (210) includes a resin isolation layer (230); The dielectric layer on the side of the paired reference layer (220) opposite to the signal transmission layer (210) includes a reinforcement layer (240), and the reinforcement layer (240) includes a base material and a resin material arranged around the base material.

2. The stacking unit (200) according to claim 1, wherein one of the two dielectric layers adjacent to the signal transmission layer (210) includes the resin isolation layer (230), and the other dielectric layer includes the reinforcement layer (240).

3. The stacking unit (200) according to claim 2, wherein the plurality of metal layers further include a power layer (250), two dielectric layers adjacent to the power layer (250) include a structural layer (260), and the structural layer (260) includes a substrate and a resin material arranged around the substrate.

4. The stacking unit (200) according to claim 3, wherein the base material in the reinforcing layer (240) and the structural layer (260) includes glass fibers, the glass fibers including a plurality of first glass fiber bundles extending along a first direction and a plurality of second glass fiber bundles extending along a second direction, the plurality of first glass fiber bundles intersecting with the plurality of second glass fiber bundles so that the glass fibers form a mesh structure.

5. The stacking unit (200) according to claim 4, wherein the first direction or the second direction has a predetermined angle with an extension direction of the signal line in the signal transmission layer (210).

6. The stacking unit (200) according to claim 4 or 5, wherein the arrangement density of the glass fibers in the reinforcing layer (240) exceeds the arrangement density of the glass fibers in the structural layer (260).

7. The laminate unit (200) of claim 4 or 5, wherein the weight ratio of glass fiber to resin in the reinforcement layer (240) exceeds the weight ratio of glass fiber to resin in the structural layer (260).

8. The stacking unit (200) according to claim 3, wherein at least one reinforcement layer (240) and / or at least one structural layer (260) is arranged between two signal transmission layers (210) adjacent to each other along the thickness direction (T).

9. A printed circuit board (100), comprising a plurality of stacking units (200) according to any one of claims 1 to 8, wherein the plurality of stacking units (200) are stacked along the thickness direction (T).

10. The printed circuit board (100) according to claim 9 further comprises a reinforcing rib (300) arranged on at least one side of the plurality of stacking units (200) along the thickness direction (T) and arranged to extend along an arrangement direction perpendicular to the thickness direction (T).

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