Manufacturing method of high-speed backboard

Abstract

The invention discloses a manufacturing method of a high-speed backboard, which comprises the following steps of: drilling a hole in a daughter board to form a mechanical hole with a through hole structure, etching a drilling-in surface and a drilling-out surface of the drilled hole to form a conductor hole ring in a manner of copper plating and pattern transfer, and forming an insulating ring around the conductor hole ring; then a photosensitive dry film is attached to the surface of the daughter board, so that the conductor hole ring and the insulating ring are exposed; tin plating is carried out on the daughter board, and metal tin completely covers the conductor hole ring; and removing the dry film on the daughter board after tin plating to expose the copper surface which is not protected by tin, then removing part of the copper surface by etching, and reserving part of the copper surface which is protected by tin on the daughter board. According to the method, when the daughter board is tinned, the conductor hole ring is completely covered with metal tin, so that the conductor hole ring is fully protected, the defect that a tin layer falls off can be eradicated, and the quality and performance of a mechanical crimping hole needing to be crimped with the high-speed connector are guaranteed.

Description

Technical Field

[0001] The invention relates to a method for manufacturing a high-speed backplane, and belongs to the technical field of PCB board design and manufacturing. Background Art

[0002] In high-speed backplane PCB products, mechanical crimping holes are designed in the sub-board layer for crimping of high-speed backplane connectors. High-speed backplane connectors are mainly used for high-speed connections between storage devices and motherboards in servers.

[0003] The current design process of mechanical crimping holes on the daughterboard layer is: pre-drill through holes on the copper surface and then do copper electroplating, then stick a photosensitive dry film on the copper surface, expose the copper pad (solder pad) and the hole through exposure and development, plate copper and tin on the exposed copper pad, use tin to protect the pad and the hole, and finally use concentrated sulfuric acid-H2O in the outer layer process. 2 O 2 The solvent removes the tin layer, exposing the mechanical blind holes that need to be crimped. The current processing design will cause the tin layer to be suspended in the air, and after being washed, rubbed and other external forces, tin will fall off, causing short circuits in the PCB board, missing pads, and affecting the plug-in performance. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for manufacturing a high-speed backplane, aiming to eliminate the defect of tin layer shedding and ensure the quality and performance of mechanical crimping holes that need to be crimped with high-speed connectors.

[0005] To achieve the above object, the present invention is implemented by adopting the following technical solutions: The present invention provides a method for manufacturing a high-speed backplane, comprising the following steps: Drilling is performed on the daughter board to form a mechanical hole of a through-hole structure. After copper plating, a conductor hole ring is etched on both the drilling entry and exit surfaces of the drilled hole by pattern transfer, and an insulating ring is formed around the conductor hole ring; A photosensitive dry film is attached to the surface of the daughter board, and after exposure and development, the conductor hole ring and the insulating ring are exposed; Tin the daughter board, and the metal tin completely covers the conductor hole ring; After tinning, the dry film on the daughter board is removed to expose the copper surface not protected by tin, and then a part of the copper surface is removed by etching, and a part of the copper surface protected by tin is retained on the daughter board; For the etched daughter board, back-drill from the conductor bridge position on the back side. After back-drilling, bond the two daughter boards together and cover the outer sides of the two daughter boards with a copper foil respectively. A dry film is applied to the outer layer, and the conductor copper at the mechanical hole position is etched away by pattern transfer to expose the conductor hole ring. Finally, the tin layer is removed to expose one end of the mechanical hole to form a mechanical crimping hole, thereby obtaining a high-speed backplane with a mechanical crimping hole.

[0006] Furthermore, the drilling of the sub-board to form a mechanical hole of the through-hole structure, after copper plating, is performed by etching a conductor hole ring on both the drilling entry surface and the drilling exit surface of the drilled hole by pattern transfer, and an insulating ring is formed around the conductor hole ring, specifically including: Drilling a hole in the daughter board to form a mechanical hole of a through-hole structure, and after copper plating, etching a first conductor hole ring on the drilling surface of the hole by pattern transfer, and forming a first insulating ring around the first conductor hole ring; By means of pattern transfer, a second conductor hole ring is etched on the drilled surface of the drill hole, a second insulating ring is formed around the second conductor hole ring, and a conductor bridge connected to the conductors on the inner and outer sides of the second insulating ring is also formed.

[0007] Further, the first insulating ring is a conductor-free region of an annular groove structure; the second insulating ring is a conductor-free region of an annular groove structure, and the conductor bridge passes through the second insulating ring.

[0008] Furthermore, the sub-board is tinned, and the metal tin completely covers the conductor hole ring, specifically including: The developed sub-board is placed in the electroplating tank and immersed in the electroplating solution containing tin salt. The current flows into the conductor bridge of the drilled layer of the sub-board. The anode tin plate in the electroplating tank undergoes an oxidation reaction. The tin atoms lose electrons and become tin ions. The sub-board acts as a cathode, and the tin ions in the electroplating solution are reduced to metallic tin, which is deposited in the holes of the sub-board and on the conductor hole rings.

[0009] Furthermore, the etched daughter boards are back-drilled from the conductor bridge position on the back side. After back-drilling, the two daughter boards are bonded together, and a copper foil is respectively covered on the outside of the two daughter boards, specifically: For the etched daughter board, back drilling is performed from the conductor bridge position on the back side, and the diameter of the back drilled hole is larger than the second conductor hole ring of the daughter board; after back drilling, the two daughter boards are bonded together with a resin sheet, and a copper foil is covered on the outside of the two daughter boards respectively, and a resin sheet is also used under the copper foil to bond the daughter boards, and holes are drilled in advance at the positions corresponding to the mechanical holes on the resin sheet to form resin sheet holes, and the diameter of the resin sheet holes is larger than the diameter of the mechanical holes on the daughter board.

[0010] Furthermore, using FeCl 3 &HCL solvent etches conductor copper.

[0011] Furthermore, the dry film on the daughter board will be removed using NAOH solvent after tin plating.

[0012] Furthermore, the back-drilled hole has a diameter 8 mil larger than the second conductor hole ring of the daughter board.

[0013] Furthermore, the diameter of the resin sheet hole is 10 mil larger than the diameter of the mechanical hole on the daughter board.

[0014] Furthermore, the two sub-boards are bonded together using a low-fluidity resin sheet; the lower side of the copper foil is also bonded by a low-fluidity resin sheet; Furthermore, the resin fluidity of the low-fluidity resin sheet is 1%-5%.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for manufacturing a high-speed backplane, wherein a photosensitive dry film is attached to the surface of a daughter board, and after exposure and development, a conductor hole ring and an insulating ring are exposed, and the daughter board is tinned. The metal tin can completely cover the conductor hole ring, thereby providing sufficient protection for the conductor hole ring, and can prevent tin from falling off after external forces such as water washing and friction, thereby eradicating the defect of tin layer falling off, and ensuring the quality and performance of mechanical crimping holes that need to be crimped with high-speed connectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of drilling and copper plating of a sub-board in a method for manufacturing a high-speed backplane provided by an embodiment of the present invention; Figure 2 It is a schematic structural diagram of a sub-board after etching in step S1 of a method for manufacturing a high-speed backplane provided by an embodiment of the present invention; Figure 3 yes Figure 2 The front view of the daughter board in FIG. Figure 4 yes Figure 2 Schematic diagram of the back of the daughter board in; Figure 5 It is a schematic diagram of the structure of a sub-board in step S2 of a method for manufacturing a high-speed backplane provided by an embodiment of the present invention.

[0017] Figure 6 It is a schematic structural diagram of a sub-board in step S3 of a method for manufacturing a high-speed backplane provided by an embodiment of the present invention; Figure 7 It is a schematic structural diagram of a sub-board in step S4 of a method for manufacturing a high-speed backplane provided by an embodiment of the present invention; Figure 8 It is a schematic structural diagram of a sub-board after back drilling in step S5 of a method for manufacturing a high-speed backboard provided by an embodiment of the present invention; Fig. 9 is a schematic diagram of the sub-board structure before bonding in step S5 of a method for manufacturing a high-speed backplane provided by an embodiment of the present invention; Fig.10It is a schematic diagram of the structure of the sub-board after bonding in step S5 of a method for manufacturing a high-speed backplane provided by an embodiment of the present invention.

[0018] Fig.11 It is a schematic diagram of the sub-board structure after copper is etched away in step S6 of a method for manufacturing a high-speed backplane provided by an embodiment of the present invention.

[0019] Fig.12 It is a schematic diagram of the structure of the sub-board after the tin protective layer is removed in step S6 of a method for manufacturing a high-speed backplane provided by an embodiment of the present invention; Fig.13 It is a schematic diagram of the structure of a sub-plate with a conductor hole ring with a tin layer in the prior art.

[0020] In the figure: 1, daughter board; 2, copper plating layer; 3, mechanical hole; 4, first conductor ring; 5, first insulating ring; 6, second conductor ring; 7, second insulating ring; 8, dry film; 9, tin protective layer; 10, back drilling hole; 11, copper foil; 12, first resin sheet; 13, second resin sheet; 14, mechanical crimping hole DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0023] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood by specific circumstances. Example

[0024] This embodiment introduces a method for manufacturing a high-speed backplane, which includes the following steps: S1. Please refer to Figure 1 , Figure 2 , Figure 3 and Figure 4 , a hole is drilled on the daughter board 1 to form a mechanical hole 3 of a through-hole structure, and after copper plating, a copper plating layer 2 is formed on the front side (drilling entry side) and back side (drilling exit side) of the daughter board 1 and inside the mechanical hole 3. Then, a first conductor hole ring 4 is etched on the drilling entry side of the hole by pattern transfer, and a first insulating ring 5 is formed around the first conductor hole ring 4, and the ring width of the first insulating ring 15 is ≥5mil.

[0025] By means of pattern transfer, a second conductor hole ring 6 is etched on the drilled surface of the drilled hole. The second conductor hole ring 6 is 2 mil smaller than the diameter of the back-drilled hole, and a second insulating ring 7 is formed around the second conductor hole 6. The ring width of the second insulating ring is ≥5 mil. A conductor bridge connected to the copper conductors on the inner and outer sides of the second insulating ring 7 is also formed.

[0026] The first insulation 5 is a conductor-free area of ​​the annular groove structure; the second insulation ring 7 is a conductor-free area of ​​the annular groove structure, and the conductor bridge passes through the second insulation ring.

[0027] S2. Please refer to Figure 5 A photosensitive dry film 8 is attached to the surface of the daughter board 1, and after exposure and development, the first conductor hole ring 4, the second conductor hole ring 6, the first insulating ring 5, the second insulating ring 7 and the conductor bridge are exposed.

[0028] S3. Please refer to Figure 6 The developed sub-board 1 is placed in an electroplating tank and immersed in an electroplating solution containing tin salt. Current flows into the conductor bridge of the drilled layer of the sub-board 1. The anode tin plate in the electroplating tank undergoes an oxidation reaction, and the tin atoms lose electrons and become tin ions. Since the sub-board 1 serves as a cathode, the tin ions in the electroplating solution are reduced to metallic tin and deposited in the mechanical holes 3, the first conductor hole ring 4 and the second conductor hole ring 6 of the sub-board 1 to form a tin protective layer 9.

[0029] It should be noted that the tin protective layer 9 completely covers the first conductor eyelet 4 and the second conductor eyelet 6 .

[0030] S4. Please refer to Figure 7 After tinning, use NAOH solvent to remove the dry film 8 on the daughter board 1, exposing the copper surface not protected by tin, and then pass FeCl 3 &HCL solvent etching removes the portion of the copper surface, and retains the portion of the copper surface protected by tin on the daughter board 1.

[0031] S5. Please refer to Figure 8 , Fig. 9 and Fig.10 For the etched daughter board 1, back drilling is performed from the conductor bridge position on the back side, and the diameter of the back drilled hole 10 is 8 mil larger than the second conductor hole ring 6 of the daughter board. After back drilling, the two daughter boards 1 are bonded together using the first resin sheet 12, and a copper foil 11 is covered on the outside of the two daughter boards 1 respectively, and the second resin sheet 13 is used under the copper foil 11 to bond with the daughter board 1, and a hole is drilled in advance at the position corresponding to the mechanical hole 3 on the first resin sheet 12, and a hole is also drilled in advance at the position corresponding to the back drilled hole 10 on the second resin sheet 13 to form a resin sheet hole, and the diameter of the resin sheet hole of the first resin sheet 12 is 10 mil larger than the diameter of the mechanical hole 3 on the daughter board 1.

[0032] In this embodiment, the first resin sheet 12 and the second resin sheet 13 are both low-fluidity resin sheets, wherein the resin fluidity of the low-fluidity resin sheet is 1%-5%.

[0033] S6. Please refer to Fig.11 and Fig.12 By sticking a dry film on the outer layer and etching away part of the copper foil 11 at the position of the mechanical hole 3 based on a pattern transfer method, exposing the first conductor hole ring 4, and finally removing the tin protective layer 9 to expose one end of the mechanical hole 3 to form a mechanical crimping hole 14, thereby obtaining a high-speed backplane with a mechanical crimping hole 14.

[0034] Please note that Figure 8 and Fig.13 , where the prior art Fig.13 In the process, the tin layer does not completely protect the conductor hole ring, that is, it is in a half-wrapped state. Therefore, the problem of tin layer hanging in the air will occur during the processing. Finally, due to the lack of tin layer protection, the PCB board will be broken and the pad will fall off. Figure 8 It can be seen that the coverage of the first conductor hole ring 4 by the tin protective layer 9 provided in the embodiment of the present invention is complete coverage, that is, a full-coverage state, which can provide sufficient protection, eliminate the defect of tin layer falling off, and ensure the quality and performance of the mechanical crimping hole 14 that needs to be crimped with a high-speed connector. Example

[0035] See also Fig.12 , This embodiment provides a high-speed backplane, which is manufactured using the high-speed backplane manufacturing method described in the above embodiment 1.

[0036] During the processing, the tin protective layer 9 is improved from the original half-encapsulation to a full-encapsulation design, which solves the problems of inner layer disconnection and pad loss caused by the shedding of the tin layer, optimizes the performance of the mechanical crimping hole, and makes it more durable and reliable.

[0037] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure rather than to limit its protection scope. Although the present disclosure has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that after reading the present disclosure, those skilled in the art can still make various changes, modifications or equivalent substitutions to the specific implementation methods of the invention, but these changes, modifications or equivalent substitutions are all within the protection scope of the disclosed claims to be approved.

Claims

1. A method for manufacturing a high-speed backplane, characterized in that: The following steps are involved: Drilling is performed on the daughter board to form a mechanical hole of a through-hole structure. After copper plating, a conductor hole ring is etched on both the drilling entry surface and the drilling exit surface of the drilled hole by pattern transfer, and an insulating ring is formed around the conductor hole ring; A photosensitive dry film is attached to the surface of the daughter board, and after exposure and development, the conductor hole ring and the insulating ring are exposed; Tin the daughter board, and the metal tin completely covers the conductor hole ring; After tinning, the dry film on the daughter board is removed to expose the copper surface not protected by tin, and then a part of the copper surface is removed by etching, and a part of the copper surface protected by tin is retained on the daughter board; For the etched daughter board, back-drill from the conductor bridge position on the back side. After back-drilling, bond the two daughter boards together and cover the outer sides of the two daughter boards with a copper foil respectively. A dry film is applied to the outer layer, and the conductor copper at the mechanical hole position is etched away by pattern transfer to expose the conductor hole ring. Finally, the tin layer is removed to expose one end of the mechanical hole to form a mechanical crimping hole, thereby obtaining a high-speed backplane with a mechanical crimping hole.

2. The method for manufacturing a high-speed backplane according to claim 1, characterized in that: The drilling process on the daughter board to form a mechanical hole of a through-hole structure, after copper plating, is used to etch a conductor hole ring on both the drilling entry surface and the drilling exit surface of the drilled hole by pattern transfer, and an insulating ring is formed around the conductor hole ring, specifically including: Drilling a hole in the daughter board to form a mechanical hole of a through-hole structure, and after copper plating, etching a first conductor hole ring on the drilling surface of the hole by pattern transfer, and forming a first insulating ring around the first conductor hole ring; By means of pattern transfer, a second conductor hole ring is formed by etching on the drilled surface of the drill hole, a second insulating ring is formed around the second conductor hole ring, and a conductor bridge connected to the conductors inside and outside the second insulating ring is also formed.

3. The method for manufacturing a high-speed backplane according to claim 2, characterized in that: The first insulating ring is a conductor-free region of an annular groove structure; the second insulating ring is a conductor-free region of an annular groove structure, and the conductor bridge passes through the second insulating ring.

4. The method for manufacturing a high-speed backplane according to claim 1, characterized in that: The sub-board is tinned, and the metal tin completely covers the conductor hole ring, specifically comprising: The developed sub-board is placed in the electroplating tank and immersed in the electroplating solution containing tin salt. The current flows into the conductor bridge of the drilled layer of the sub-board. The anode tin plate in the electroplating tank undergoes an oxidation reaction. The tin atoms lose electrons and become tin ions. The sub-board acts as a cathode, and the tin ions in the electroplating solution are reduced to metallic tin, which is deposited in the holes of the sub-board and on the conductor hole rings.

5. The method for manufacturing a high-speed backplane according to claim 1, characterized in that: The etched daughter board is back-drilled from the conductor bridge position on the back side. After back-drilling, the two daughter boards are bonded together, and a copper foil is respectively covered on the outside of the two daughter boards. Specifically: For the etched daughter board, back drilling is performed from the conductor bridge position on the back side, and the diameter of the back drilled hole is larger than the second conductor hole ring of the daughter board; after back drilling, the two daughter boards are bonded together with a resin sheet, and a copper foil is covered on the outside of the two daughter boards respectively, and a resin sheet is also used under the copper foil to bond the daughter boards, and holes are drilled in advance at the positions corresponding to the mechanical holes on the resin sheet to form resin sheet holes, and the diameter of the resin sheet holes is larger than the diameter of the mechanical holes on the daughter board.

6. The method for manufacturing a high-speed backplane according to claim 1, characterized in that: Conductor copper is etched using FeCl3 & HCL solvent.

7. The method for manufacturing a high-speed backplane according to claim 1, characterized in that: Using NAOH solvent after tinning will remove the dry film on the daughter board.

8. The method for manufacturing a high-speed backplane according to claim 1, characterized in that: The back-drilled hole has a diameter 8 mil larger than the second conductor hole ring of the daughter board.

9. The method for manufacturing a high-speed backplane according to claim 1, characterized in that: The diameter of the resin sheet hole is 10 mil larger than the diameter of the mechanical hole on the daughter board.

10. The method for manufacturing a high-speed backplane according to claim 1, characterized in that: The two sub-boards are bonded together using a low-fluidity resin sheet; the lower side of the copper foil is also bonded by a low-fluidity resin sheet; The resin fluidity of the low-fluidity resin sheet is 1%-5%.

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