A golden finger connection structure of a PCB

Abstract

The utility model provides a gold finger connection structure of PCB board, including being located in the PCB board in: first base layer, including first copper foil, first copper foil includes superimposed area and step area, second base layer, including second copper foil, be equipped with high speed signal line on second copper foil, first blind hole, first blind hole passes first copper foil with second copper foil, to make first copper foil and second copper foil conduction, gold finger, be located in first copper foil's step area, wherein, second base layer is superimposed in superimposed area, and the projection of second base layer on first base layer falls in the range of superimposed area, the gold finger connection structure of the utility model can ensure the stripping strength requirement, satisfies the high frequency high speed transmission demand of high speed signal line.

Description

Technical Field

[0001] This utility model relates to the field of circuit board manufacturing technology, and more specifically, to a gold finger connection structure for a PCB board. Background Technology

[0002] With the rapid development of AI computing power, the traditional PCIe computing power loss requirements can no longer meet the development requirements of products. New products need to be upgraded and have higher requirements for signal transmission and loss. The main problems with the current stepped gold finger design are: 1. Currently, high-speed signal lines and stepped gold fingers are designed on the same layer of copper foil. During wiring, because the high-speed signal lines are very long, part of them are inside the board and the other part extends to the stepped part used to support the gold fingers to connect with them. This results in a part of the high-speed signal lines being exposed outside the board, making them susceptible to air interference and affecting the transmission effect. 2. Because the gold fingers need to be inserted and removed, the copper foil supporting the gold fingers needs to meet a certain peel strength (usually 3 pounds). Traditional PCIe stepped gold finger layers usually use non-high-speed copper foils such as HTE / RTF, which can meet the peel strength requirement of more than 3 pounds to adapt to the insertion and removal of gold fingers. However, with the need for high-speed signal iteration, traditional non-high-speed copper foils can no longer meet the requirements of high-frequency and high-speed signal transmission. At present, the industry uses high-speed copper foils, such as HVLP3 / HVLP4, to replace traditional non-high-speed copper foils. However, the peel strength of such high-speed copper foils is worse than that of traditional HTE / RTF1 copper foils, which can only reach about 2.2 pounds. This cannot meet the peel strength requirement of 3 pounds at the gold finger position. Long-term use can easily lead to poor contact of the gold fingers or even failure, seriously affecting the service life and reliability. Utility Model Content

[0003] In view of this, the present invention provides a gold finger connection structure for a PCB board to solve the problems of high-speed signal lines being affected by air interference and the insufficient peel strength of existing high-speed copper foil.

[0004] This utility model is achieved through the following technical solution.

[0005] A gold finger connection structure for a PCB board includes: a first base layer comprising a first copper foil, the first copper foil including a stacked area and a stepped area; a second base layer comprising a second copper foil, the second copper foil having a high-speed signal line; a first blind via passing through the first copper foil and the second copper foil to enable conduction between the first copper foil and the second copper foil; and a gold finger disposed on the stepped area of ​​the first copper foil; wherein the second base layer is stacked on the stacked area, and the projection of the second base layer on the first base layer falls within the range of the stacked area.

[0006] In the above scheme, the PCB board has a layered structure, with the first base layer and the second base layer being two layers. The stepped area of ​​the first copper foil is used for gold plating to form gold fingers. The second copper foil has high-speed signal lines, and the gold fingers can be electrically connected to the high-speed signal lines on the second base layer through the first blind via. Since the first and second copper foils are located in different layers, different types of copper foil can be selected. The first base layer requires high peel strength because the gold fingers need to be inserted and removed. The second base layer, which carries the high-speed signal lines, needs to meet the high-frequency and high-speed signal transmission requirements of the high-speed signal lines, so high-speed copper foil is selected for the second copper foil. This utility model sets the gold fingers and high-speed signal lines in different layers, thereby allowing the selection of two different types of copper foil, satisfying both the peel strength at the gold finger location and the high-speed signal transmission requirements of the high-speed signal lines.

[0007] Since the high-speed signal line does not pass through the first base layer where the stepped gold fingers are located, it is located entirely inside the PCB board, which can effectively avoid the influence and interference of air on high-speed signal transmission, ensure signal transmission quality, and meet the needs of scenarios with extremely high signal transmission requirements.

[0008] In one example of this utility model, the first copper foil is either HTE copper foil or RTF copper foil.

[0009] In the above solution, HTE copper foil and RTF copper foil are traditional copper foils, which have high peel strength and can effectively meet the insertion and removal requirements at the gold finger position.

[0010] In one example of this invention, the second copper foil is an HVLP copper foil.

[0011] In the above scheme, the HVLP copper foil has low roughness and high conductivity, which can reduce loss and distortion during signal transmission and effectively meet the requirements of high-frequency and high-speed signal transmission.

[0012] In one example of this utility model, a plurality of gold finger pads are spaced apart on the stepped area.

[0013] In the above scheme, the gold finger pads are used as a carrier for subsequent gold plating to form and obtain the gold fingers.

[0014] In one example of this utility model, a plurality of second blind vias are also included, which pass through the gold finger pads and are configured to correspond one-to-one with the gold finger pads.

[0015] In the above scheme, each gold finger pad is provided with a second blind hole. The second blind hole is used to make the gold finger pad and the first copper foil conduction, so that the gold finger and the first copper foil conduction, thereby connecting the gold finger to the high-speed signal line on the second copper foil.

[0016] In one example of this invention, the gold finger pads are distributed in pairs, and the distance from the second blind via to a set of adjacent sides of the gold finger pads is equal.

[0017] In the above scheme, the second blind via is located at the corner of the gold finger pad, and its distance to the two sides corresponding to the corner is equal to reduce impedance abrupt changes and ensure the integrity of high-speed signals.

[0018] In one example of this invention, the two second blind holes corresponding to each pair of gold finger pads are symmetrical about the gap between the two gold finger pads.

[0019] In one example of this utility model, the first base layer further includes a first core board, the second base layer further includes a second core board, the first copper foil is attached to the surface of the first core board, the second copper foil is attached to the surface of the second core board, and the second core board is located between the first copper foil and the second copper foil.

[0020] In the above scheme, the core board is used to provide mechanical strength and stability for the multilayer circuit board and to provide support for the copper foil.

[0021] In one example of this utility model, a solder resist layer is further provided on the stepped area, and the solder resist layer is attached to the part of the stepped area other than the gold finger.

[0022] In the above scheme, the solder mask layer is used to prevent the stepped area of ​​the first copper foil from being exposed to the air to avoid oxidation of the copper foil. At the same time, it also serves as an insulating layer.

[0023] As can be seen from the above, the beneficial effects of this utility model are as follows: This invention sets the gold finger and the high-speed signal line in the first base layer and the second base layer respectively. By setting two different types of copper foil in the first base layer and the second base layer respectively, and making the two copper foils conductive through the first blind hole, the advantages of the two copper foils are combined. While ensuring the peel strength requirements of the first base layer, the high frequency and high speed transmission requirements of the high-speed signal line of the second base layer are met. In this invention, the high-speed signal line and the gold finger are located on different layers. The high-speed signal line is completely located inside the PCB board, which can effectively avoid the influence and interference of air on high-speed signal transmission, ensure signal transmission quality, and meet the needs of scenarios with extremely high signal transmission requirements. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a superimposed diagram of the gold finger connection structure portion of one embodiment.

[0026] Figure 2 This is a top view of one pair of gold finger pads.

[0027] Explanation of the reference numerals in the figure: 1-First base layer; 11-First copper foil; 111-Overlapping area; 112-Stepped area; 12-First core board; 2-Second base layer; 21-Second copper foil; 22-Second core board; 3-First blind via; 4-Gold finger; 5-Gold finger pad; 6-Second blind via; 7-Solder resist layer; 8-Prepreg. Detailed Implementation

[0028] To facilitate understanding of this invention, a more comprehensive description will be provided below with reference to the accompanying drawings. The drawings illustrate preferred embodiments of the invention. However, this invention can be implemented in many different forms and is not limited to the embodiments described herein.

[0029] Please refer to Figure 1 A cross-sectional schematic diagram of the gold finger connection structure of a PCB board is shown, including a first base layer 1, a second base layer 2, a first blind via 3, and a gold finger 4 disposed within the PCB board. The first base layer 1 includes a first copper foil 11, which includes a stacking area 111 and a stepped area 112; the second base layer 2 includes a second copper foil 21, on which a high-speed signal line is provided; the first blind via 3 passes through the first copper foil 11 and the second copper foil 21 to enable the first copper foil 11 and the second copper foil 21 to conduct; the gold finger 4 is disposed on the stepped area 112 of the first copper foil 11; wherein, the second base layer 2 is stacked on the stacking area 111, and the projection of the second base layer 2 on the first base layer 1 falls within the range of the stacking area 111.

[0030] It should be noted that the PCB board is a multilayer board. The attached figure only shows the structure of the first base layer 1 and the second base layer 2. The rest of the parts are not shown in detail. In addition, the high-speed signal line is obtained by etching on the second copper foil 21, which is not shown in detail in the figure.

[0031] Specifically, the PCB board has a layered structure, with the first base layer 1 and the second base layer 2 being two of the layers, and the stepped area 112 of the first copper foil 11 (i.e. Figure 1 The portion on the right side (not overlapping with the second base layer 2) is plated with gold to form a gold finger 4. A high-speed signal line is provided on the second copper foil 21. The gold finger 4 can be electrically connected to the high-speed signal line on the second base layer 2 through the first blind hole 3. Since the first copper foil 11 and the second copper foil 21 are located in different layers, the first base layer 1 and the second base layer 2 can be selected from different types of copper foil. The first base layer 1, because it has the gold finger 4, needs to be inserted and removed, so the first copper foil 11 needs to be a copper foil with high peel strength. The second base layer 2, which carries the high-speed signal line, needs to meet the high-frequency and high-speed signal transmission requirements of the high-speed signal line, so the second copper foil 21 is a high-speed copper foil with high conductivity. This application combines the advantages of two different types of copper foil by setting the gold finger 4 and the high-speed signal line in different layers, so as to meet the peel strength at the location of the gold finger 4 and the high-speed signal transmission requirements of the high-speed signal line.

[0032] Since the high-speed signal line does not pass through the first base layer 1 where the stepped gold finger 4 is located, it is completely located inside the PCB board, which can effectively avoid the influence and interference of air on high-speed signal transmission, ensure signal transmission quality, and meet the needs of scenarios with extremely high signal transmission requirements.

[0033] Understandably, after the gold finger 4 is initially formed, it is located in the inner layer of the PCB board. Subsequently, by opening a window in the outer layer, the part covering the gold finger 4 is removed to expose the gold finger 4.

[0034] Preferably, the first copper foil 11 is selected from HTE copper foil or RTF copper foil. HTE copper foil and RTF copper foil can meet the peel strength requirement of more than 3 pounds, thereby effectively meeting the insertion and removal requirements at the position of gold finger 4.

[0035] Preferably, the second copper foil 21 is HVLP copper foil. HVLP copper foil has low roughness and high conductivity, which can reduce loss and distortion during signal transmission and effectively meet the requirements of high-frequency and high-speed signal transmission. In this embodiment, the second copper foil 21 is preferably HVLP3 or HVLP4 copper foil.

[0036] Please refer to Figure 2 Multiple gold finger pads 5 are spaced apart on the stepped area 112. The gold finger pads 5 are used as carriers for subsequent gold plating to form gold fingers 4.

[0037] The PCB board also includes several second blind holes 6. The second blind holes 6 pass through the gold finger pads 5 and are set one-to-one with the gold finger pads 5. The second blind holes 6 are used to make the gold finger pads 5 and the first copper foil 11 conduct, so that the gold finger 4 and the first copper foil 11 conduct, thereby connecting the gold finger 4 to the high-speed signal line on the second copper foil 21.

[0038] It should be noted that the second blind hole 6 is processed before the gold finger 4 is gold-plated and formed. Figure 1 It is not shown in detail that after gold plating to obtain gold finger 4, gold finger 4 is exposed by opening a window.

[0039] It should also be noted that since the mainstream transmission method for high-speed signals is differential signal transmission, such as the PCIe interface, the gold fingers 4 need to be designed in pairs in a "differential pair" format to adapt to differential signal transmission. Correspondingly, the gold finger pads 5 are also distributed in pairs. Figure 2 This is a top view of one of the gold finger pads 5.

[0040] Among them, such as Figure 2 As shown, the second blind via 6 is located at the corner of the gold finger pad 5, and the distance from the second blind via 6 to a set of adjacent sides corresponding to the corner of the gold finger pad 5 is equal, and the distance from the second blind via 6 to the two sides corresponding to the corner is equal, so as to avoid impedance abrupt changes and ensure the integrity of high-speed signals.

[0041] Furthermore, the two second blind holes 6 corresponding to each pair of gold finger pads 5 are symmetrical about the gap between the two gold finger pads 5. By making the two second blind holes 6 mirror symmetrical, the transmission path, impedance and coupling of the high-speed differential signal are consistent, eliminating the risk of signal distortion and ensuring signal transmission quality.

[0042] Please refer to Figure 1 The first base layer 1 also includes a first core board 12, and the second base layer 2 also includes a second core board 22. The first copper foil 11 is attached to the surface of the first core board 12, and the second copper foil 21 is attached to the surface of the second core board 22. The second core board 22 is located between the first copper foil 11 and the second copper foil 21. The core board is used to provide mechanical strength and stability for the multilayer circuit board and can provide support for the copper foil.

[0043] Furthermore, a solder resist layer 7 is provided on the stepped area 112. The solder resist layer 7 is attached to the part of the stepped area 112 except for the gold finger 4. The solder resist layer 7 is used to prevent the stepped area 112 part of the first copper foil 11 from being exposed to the air, so as to prevent the copper foil from oxidizing. At the same time, it can also play the role of insulation and isolation.

[0044] Please refer to Figure 1 A semi-cured sheet 8 is provided on the side of the second base layer 2 away from the first base layer 1. The semi-cured sheet 8 is used to bond with the remaining layers.

[0045] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0046] Furthermore, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0047] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. The various embodiments can be combined as needed, and the same or similar parts can be referred to each other.

[0048] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A gold finger connection structure for a PCB board, characterized in that, Including those located within the PCB board: The first base layer includes a first copper foil, which includes an overlay area and a stepped area; The second base layer includes a second copper foil, on which high-speed signal lines are provided; A first blind via passes through the first copper foil and the second copper foil to make the first copper foil and the second copper foil conductive; The gold fingers are disposed on the stepped area of ​​the first copper foil; The second base layer is stacked on the stacking area, and the projection of the second base layer on the first base layer falls within the range of the stacking area.

2. The gold finger connection structure of the PCB board according to claim 1, characterized in that, The first copper foil is either HTE copper foil or RTF copper foil.

3. The gold finger connection structure of the PCB board according to claim 1, characterized in that, The second copper foil is an HVLP copper foil.

4. The gold finger connection structure of the PCB board according to claim 1, characterized in that, The stepped area is provided with multiple gold finger pads at intervals.

5. The gold finger connection structure of the PCB board according to claim 4, characterized in that, It also includes several second blind vias, which pass through the gold finger pads and are configured to correspond one-to-one with the gold finger pads.

6. The gold finger connection structure of the PCB board according to claim 5, characterized in that, The gold finger pads are distributed in pairs, and the distance from the second blind via to a set of adjacent sides of the gold finger pads is equal.

7. The gold finger connection structure of the PCB board according to claim 6, characterized in that, The two second blind vias corresponding to each pair of gold finger pads are symmetrical about the gap between the two gold finger pads.

8. The gold finger connection structure of the PCB board according to claim 1, characterized in that, The first base layer further includes a first core board, and the second base layer further includes a second core board. The first copper foil is attached to the surface of the first core board, the second copper foil is attached to the surface of the second core board, and the second core board is located between the first copper foil and the second copper foil.

9. The gold finger connection structure of the PCB board according to claim 1, characterized in that, The stepped area is also provided with a solder resist layer, which is attached to the part of the stepped area other than the gold finger.

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