Thick PCB board via production method and PCB board

Abstract

The present application relates to the field of PCB production, and discloses a method for making vias on thick PCB boards, the method comprising: processing a pre-drilled hole that penetrates the thick PCB board; wherein the aperture of the pre-drilled hole is larger than the aperture of the via to be made, and the designed board thickness of the thick PCB board is greater than 5mm; after copper deposition and full-board electroplating of the thick PCB board, a primary copper layer is formed in the pre-drilled hole, and the hole is expanded from the end of the pre-drilled hole to the middle of the pre-drilled hole by controlled depth drilling to obtain an expanded hole section; the thick PCB board is subjected to secondary full-board electroplating to thicken the copper layer in the pre-drilled hole, and a secondary copper layer is formed in the pre-drilled hole to obtain a completed via. The designed board thickness of the thick PCB board is 6.0mm±10%, the aperture design tolerance of the via is ±0.03mm, and the minimum copper thickness of the inner wall of the via is ≥30μm. The present application can produce qualified PCB board vias on thick PCB boards by improving the process.

Description

Technical Field

[0001] The present application relates to the technical field of PCB production, and more specifically, to a method for making vias of a thick PCB board and a PCB board. Background Art

[0002] Printed Through-Hole (PTH), also known as Via. It is a structure on a printed circuit board (PCB) that is used to establish electrical connections between different circuit layers or to connect to components on the surface of the PCB. Vias consist of holes formed on the PCB by electrolysis or mechanical means, and pass through the entire PCB in the direction of the PCB thickness. The inner wall of the via is metallized (such as electroplated copper) to provide electrical connectivity. Structurally, vias can be used to transmit signals, conduct currents, and connect electrically between different circuit layers. For example, when a signal line needs to be led out from one layer to another, it can be connected through a via. Similarly, when components need to be mounted on the PCB surface, the component pins are connected to the internal circuit layer through vias to achieve electrical connections.

[0003] The existing PCB production equipment generally has a processing capacity of 0.3-4.8mm thick PCB boards. However, when the thickness of the PCB board reaches 5.0mm or above, due to the joint limitations of electroplating solutions, equipment and other factors, the copper thickness in the middle part of the PCB board via hole cannot reach the design value, or the hole copper in the middle part of the PCB board via hole reaches the required value, but the aperture at the hole mouth of the PCB board via hole is reduced, exceeding the design tolerance value of the PCB board via hole diameter, resulting in difficulty in producing qualified PCB board via holes. Summary of the invention

[0004] The purpose of the present application is to provide a method for producing vias on a thick PCB board, which solves the technical problem that it is difficult to produce qualified PCB board vias when the PCB board is thick, and achieves the technical effect of being able to produce qualified PCB board vias on a thick PCB board.

[0005] The embodiment of the present application provides a method for making a via hole in a thick PCB board, the method comprising: processing a pre-drilled hole that penetrates the thick PCB board; wherein the aperture of the pre-drilled hole is larger than the aperture of the via hole to be made, and the designed board thickness of the thick PCB board is larger than 5 mm; after copper deposition and full-board electroplating of the thick PCB board, a primary copper layer is formed in the pre-drilled hole, and the hole is expanded from the end of the pre-drilled hole to the middle of the pre-drilled hole by controlled depth drilling to obtain an expanded hole section; the thick PCB board is subjected to a second full-board electroplating to thicken the copper layer in the pre-drilled hole, and a secondary copper layer is formed in the pre-drilled hole to obtain a completed via hole.

[0006] In a possible implementation, the design thickness of the thick PCB board is 6.0 mm±10%, the design tolerance of the via hole diameter is ±0.03 mm, and the minimum copper thickness of the inner wall of the via hole is ≥30 μm.

[0007] In another possible implementation, the current density of the first full-board electroplating is greater than the current density of the second full-board electroplating, and the plating time of the first full-board electroplating is less than the plating time of the second full-board electroplating.

[0008] In another possible implementation, the parameters for the first full-board electroplating are designed to be 90 minutes of electroplating and a current density of 1.7ASD; the parameters for the second full-board electroplating are designed to be 150 minutes of electroplating and a current density of 1.2ASD; the copper sulfate concentration for the first full-board electroplating and the second full-board electroplating is 50-60g / L, and the sulfuric acid concentration is 120-130ml / L.

[0009] In another possible implementation, the expansion section presents a tapered structure that decreases from the end of the pre-drilled hole to the middle of the pre-drilled hole.

[0010] In another possible implementation, during the primary full-board electroplating and the secondary full-board electroplating, metal electroplating edge strips for conducting current to the thick PCB are clamped on a set of opposite edges of the thick PCB.

[0011] In another possible implementation, when the thick PCB board is a chemical tin-immersion board, a chemical nickel-gold-immersion board or a chemical silver-immersion board, the difference between the diameter of the pre-drilled hole and the diameter of the via to be made is 0.1mm; when the thick PCB board is a tin-sprayed board, the difference between the diameter of the pre-drilled hole and the diameter of the via to be made is 0.15mm.

[0012] In another possible implementation, when the thick PCB board is a chemical tin-immersion board, a chemical nickel-gold-immersion board or a chemical silver-immersion board, the depth of the expansion section is 0.5 mm to 1.2 mm; when the thick PCB board is a tin-spraying board, the depth of the expansion section is 1.2 mm to 1.8 mm.

[0013] In another possible implementation, when the thick PCB board is a chemical tin-immersion board, a chemical nickel-gold-immersion board or a chemical silver-immersion board, the opening angle of the expansion section is 10° to 13°; when the thick PCB board is a tin-spraying board, the opening angle of the expansion section is 13° to 18°.

[0014] An embodiment of the present application provides a PCB board, and the via holes of the PCB board are manufactured by the above method.

[0015] Compared with the prior art, the embodiments of the present invention have the following beneficial effects:

[0016] The embodiment of the present application provides a method for making vias of a thick PCB board, and the method includes: processing a pre-drilled hole that penetrates the thick PCB board; wherein the aperture of the pre-drilled hole is larger than the aperture of the via to be made, and the designed board thickness of the thick PCB board is larger than 5mm; after copper deposition and full-board electroplating of the thick PCB board, a primary copper layer is formed in the pre-drilled hole, and the hole is expanded from the end of the pre-drilled hole to the middle of the pre-drilled hole by controlled depth drilling to obtain an expanded hole section; the thick PCB board is subjected to secondary full-board electroplating to thicken the copper layer in the pre-drilled hole, and a secondary copper layer is formed in the pre-drilled hole to obtain a completed via. The embodiment of the present application can produce qualified PCB board vias on thick PCB boards, and improve the production efficiency of PCB board vias. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0018] Figure 1 A schematic diagram of a process for making vias in a thick PCB provided in an embodiment of the present application;

[0019] Figure 2 A schematic diagram of the process of copper deposition and primary electroplating on a thick PCB provided in an embodiment of the present application;

[0020] Figure 3 A schematic diagram of the structure after pre-drilling holes on a thick PCB board provided in an embodiment of the present application;

[0021] Figure 4 for Figure 3 Schematic diagram of the local structure at A in FIG.

[0022] Figure 5 A schematic diagram of the structure of secondary electroplating on a thick PCB board provided in an embodiment of the present application;

[0023] Figure 6 for Figure 5 Schematic diagram of the local structure at B in FIG.

[0024] In the figure, 1, thick PCB board; 11, pre-drilled hole; 111, primary copper layer; 112, hole expansion section; 113, secondary copper layer; 12, via. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0026] It should be noted that when a component or structure is referred to as being "fixed to" or "disposed on" another component or structure, it may be directly on the other component or structure or indirectly on the other component or structure. When a component or structure is referred to as being "connected to" another component or structure, it may be directly connected to the other component or structure or indirectly connected to the other component or structure.

[0027] It should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or a component or structure referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0028] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0029] In the prior art, when the thickness of the PCB board reaches 5.0 mm or above, due to the joint limitations of electroplating solutions, equipment and other factors, the copper thickness in the middle part of the PCB board via hole does not reach the design value, or the hole copper in the middle part of the PCB board via hole reaches the required value, but the hole diameter at the hole mouth of the PCB board via hole is reduced, resulting in difficulty in producing qualified PCB board via holes.

[0030] Based on the above reasons, the embodiment of the present application provides a method for making vias in a thick PCB board, and the method includes: processing a pre-drilled hole that passes through the thick PCB board; wherein the aperture of the pre-drilled hole is larger than the aperture of the via that needs to be made, and the designed board thickness of the thick PCB board is greater than 5mm; after copper deposition and full-board electroplating of the thick PCB board, a primary copper layer is formed in the pre-drilled hole, and the hole is expanded from the end of the pre-drilled hole to the middle of the pre-drilled hole by controlled depth drilling to obtain an expanded hole section; the thick PCB board is subjected to a second full-board electroplating to thicken the copper layer in the pre-drilled hole, and a secondary copper layer is formed in the pre-drilled hole to obtain a completed via. The embodiment of the present application can produce qualified PCB board vias on thick PCB boards, and improve the production efficiency of PCB board vias.

[0031] In some scenarios, a method for producing vias on a thick PCB board according to an embodiment of the present application can be used to produce vias on a thick PCB board with a thickness greater than 5 mm, thereby improving the production efficiency of the vias.

[0032] The following is a detailed description of a method for making vias in a thick PCB board provided in an embodiment of the present application with reference to specific examples.

[0033] Figure 1 A schematic diagram of a process for making a via hole in a thick PCB board provided in an embodiment of the present application is shown in FIG. Figure 1 As shown, the embodiment of the present application includes S110 to S130, and S110 to S130 are described in detail below.

[0034] S110, processing a pre-drilled hole 11 penetrating the thick PCB board 1. The diameter of the pre-drilled hole 11 is larger than the diameter of the via hole 12 to be made, and the designed board thickness of the thick PCB board 1 is greater than 5 mm.

[0035] When using, Figure 2 A schematic diagram of the process of copper deposition and primary electroplating of a thick PCB board provided in an embodiment of the present application is shown in FIG. Figure 2 As shown, when processing a via hole on a thick PCB board 1, firstly a pre-drilled hole 11 penetrating the thick PCB board 1 is processed, and then the pre-drilled hole 11 is further processed to obtain a processed via hole.

[0036] Exemplarily, the pre-drilled holes 11 can be processed on the thick PCB board 1 by drilling.

[0037] Structurally, the diameter of the pre-drilled hole 11 is larger than the diameter of the via hole 12 to be made, and then the copper layer is processed in the pre-drilled hole 11 to obtain the via hole 12 with the copper layer attached in the processed hole.

[0038] In terms of structure, Figure 1 As shown, the designed board thickness H of the thick PCB board 1 can be greater than 5 mm.

[0039] S120, after copper deposition and full-board electroplating of the thick PCB board 1, a primary copper layer 111 is formed in the pre-drilled hole 11, and the hole is expanded from the end of the pre-drilled hole 11 to the middle of the pre-drilled hole 11 by controlled depth drilling to obtain an expanded hole section 112.

[0040] During processing, copper deposition can only form a maximum copper layer of 2μm in the hole, while electroplating can form a thicker copper layer in the hole. Since the copper layer thickness in the via hole of the PCB board is generally required to be at least 25μm, the copper layer needs to be processed in the via hole through the electroplating process.

[0041] When in use, a copper layer can be initially formed in the pre-drilled hole 11 by copper plating, and then the copper layer in the pre-drilled hole 11 can be thickened by a full-board electroplating. This can prevent the copper plating layer formed in the hole during the copper plating process from being disconnected, resulting in no copper in the pre-drilled hole 11.

[0042] like Figure 2 As shown, after the copper layer is formed in the pre-drilled hole 11 by a full-board electroplating, the depth of the pre-drilled hole 11 is too large due to the excessive thickness of the thick PCB board 1. Under the joint limitations of electroplating solutions, equipment and other factors, the copper thickness of the primary copper layer 111 in the middle of the pre-drilled hole 11 does not meet the standard, and the copper thickness of the primary copper layer 111 at the opening of the pre-drilled hole 11 is relatively large, resulting in a smaller aperture size of the pre-drilled hole 11.

[0043] During processing, Figure 2 As shown, due to the current effect at the tip during copper electroplating, the copper thickness of the primary copper layer 111 at the opening of the pre-drilled hole 11 will be larger.

[0044] Figure 3 A schematic diagram of the structure after pre-drilling holes on a thick PCB board provided in an embodiment of the present application, Figure 4 for Figure 3 The local structure diagram at A in Figure 3 and Figure 4 As shown, in order to solve the problem that the copper thickness of the primary copper layer 111 at the opening of the pre-drilled hole 11 is too thick and the aperture size of the pre-drilled hole 11 becomes smaller, the hole can be expanded from the end of the pre-drilled hole 11 to the middle of the pre-drilled hole 11 by controlled depth drilling to obtain an expanded section 112, and the expanded section 112 is used to remove the thicker area in the primary copper layer 111 at the opening of the pre-drilled hole 11.

[0045] S130 , performing secondary full-board electroplating on the thick PCB board 1 to thicken the copper layer in the pre-drilled hole 11 , forming a secondary copper layer 113 in the pre-drilled hole 11 , and obtaining a completed via hole 12 .

[0046] During processing, in order to thicken the primary copper layer 111 in the pre-drilled hole 11, the thick PCB board 1 can be subjected to secondary full-board electroplating to thicken the copper layer in the pre-drilled hole 11, that is, a secondary copper layer 113 is formed in the pre-drilled hole 11, and the secondary copper layer 113 meets the thickness requirement of the copper layer in the via hole 12, thereby obtaining a completed via hole 12.

[0047] When in use, the secondary full-board electroplating mainly thickens the copper plating thickness in the pre-drilled hole 11 to a required value, for example, 25 μm.

[0048] During processing, the secondary full-board electroplating can increase the copper thickness in the pre-drilled hole 11. Since the hole is expanded from the end of the pre-drilled hole 11 to the middle of the pre-drilled hole 11 through controlled depth drilling to obtain the expanded hole section 112, the expanded hole section 112 can eliminate the influence of the tip current effect during the secondary full-board electroplating, so that the diameter of the hole edge of the via 12 and the middle of the via 12 meet the aperture requirements of the via 12.

[0049] The beneficial effect brought about by the above-mentioned implementation method is that after the pre-drilled hole is electroplated once throughout the board, an expansion section is processed at the hole position of the pre-drilled hole to eliminate the problem of the hole diameter being too small caused by the current effect at the tip when electroplating copper, and the copper thickness in the pre-drilled hole is increased by secondary full-board electroplating. The expansion section can eliminate the problem of the hole diameter being too small caused by the current effect at the tip when electroplating copper, so that the copper thickness in the middle of the via meets the thickness requirement, and the processing of the via is completed.

[0050] In some implementations, the designed board thickness of the thick PCB board 1 is 6.0 mm±10%, the aperture design tolerance of the via hole 12 is ±0.03 mm, and the minimum copper thickness of the inner wall of the via hole 12 is ≥30 um.

[0051] In terms of structure, the designed thickness of the thick PCB board 1 can be 6.0 mm±10%, which is suitable for processing via holes of thick PCB boards 1 with larger thickness.

[0052] Structurally, the aperture design tolerance of the via hole 12 is ±0.03 mm, which is suitable for processing the via hole 12 with an aperture design tolerance within a relatively small range.

[0053] Structurally, the minimum copper thickness of the inner wall of the via hole 12 is ≥30 μm, which is suitable for processing the via hole 12 with the minimum copper thickness of the inner wall being ≥30 μm.

[0054] The beneficial effect brought by the above implementation method is that it is suitable for producing and processing vias with a designed board thickness of 6.0 mm ± 10%, a hole diameter design tolerance of ± 0.03 mm, and a minimum inner wall copper thickness of ≥ 30 um.

[0055] In some implementations, the current density of the first full-plate electroplating is greater than the current density of the second full-plate electroplating, and the plating time of the first full-plate electroplating is less than the plating time of the second full-plate electroplating.

[0056] During processing, since the main purpose of one-time full-board electroplating is to thicken the copper layer obtained by copper deposition in the pre-drilled hole 11 and prevent the copper deposition layer in the pre-drilled hole 11 from being disconnected and causing the defect of no copper in the pre-drilled hole 11, one-time full-board electroplating uses a larger current and a shorter time for electroplating, which can have a better thickening and reinforcement effect on the copper layer obtained by copper deposition in the pre-drilled hole 11 and shorten the production cycle at the same time.

[0057] During processing, the secondary full-board electroplating needs to thicken the copper thickness in the pre-drilled hole 11 to the required value. Using a lower current and longer time electroplating process during the secondary full-board electroplating will reduce the current effect at the tip of the hole edge during electroplating, increase the deep plating ability of electroplating, and make the thickness of the electroplated copper layer in the pre-drilled hole 11 more uniform, thereby ensuring the production quality of the via 12.

[0058] The beneficial effect brought about by the above-mentioned implementation method is that a larger current is used for electroplating the entire board at one time, which can achieve a better thickening and reinforcement effect on the copper layer obtained by copper deposition in the pre-drilled holes, and at the same time, shorten the production cycle.

[0059] The beneficial effect brought about by the above-mentioned implementation method is that the use of a lower current and longer time electroplating process during the secondary full-board electroplating will reduce the current effect at the tip of the hole edge during electroplating, increase the deep plating ability of electroplating, and make the thickness of the electroplated copper layer in the pre-drilled hole more uniform, thereby ensuring the production quality of the via.

[0060] In some implementations, the parameters for a first full-plate electroplating can be designed to be electroplating for 90 minutes and a current density of 1.7 ASD; the parameters for a second full-plate electroplating can be designed to be electroplating for 150 minutes and a current density of 1.2 ASD.

[0061] In some implementations, the copper sulfate concentration of the first full-board electroplating and the second full-board electroplating may be 50-60 g / L, and the sulfuric acid concentration may be 120-130 ml / L.

[0062] The beneficial effect brought about by the above implementation method is that the electroplating process parameters are reasonably designed to improve the electroplating quality of the PCB board.

[0063] In some implementations, the expansion section 112 has a tapered structure that decreases from the end of the pre-drilled hole 11 to the middle of the pre-drilled hole 11 .

[0064] Figure 5 A schematic diagram of the structure of secondary electroplating on a thick PCB board provided in an embodiment of the present application, Figure 6 for Figure 5 The local structure diagram at B in FIG. Figures 3 to 6As shown, structurally, the expansion section 112 presents a tapered structure that decreases from the end of the pre-drilled hole 11 to the middle of the pre-drilled hole 11. The tapered structure of the expansion section 112 can gradually increase its ability to offset the tip current effect during electroplating from the middle of the pre-drilled hole 11 to the end of the pre-drilled hole 11, so that the copper layer thickness of the expansion section 112 meets the design requirements after the secondary full-board electroplating, and the aperture of the via 12 meets the design requirements.

[0065] The beneficial effect brought about by the above-mentioned implementation method is that the tapered structure of the hole expansion section can gradually increase its ability to offset the tip current effect during electroplating from the middle of the pre-drilled hole to the end of the pre-drilled hole, so that the copper layer of the hole expansion section meets the design requirements after the secondary full-board electroplating.

[0066] In some implementations, during the primary full-board electroplating and the secondary full-board electroplating, metal electroplating edge strips for conducting current to the thick PCB board 1 are clamped on a set of opposite edges of the thick PCB board 1 .

[0067] When in use, metal electroplating edge strips for conducting current to the thick PCB board 1 are clamped on a group of opposite sides of the thick PCB board 1. The electroplating edge strip is a metal plate fixed on the side of the thick PCB board 1 when the thick PCB board 1 is electroplated, so as to reduce the current on the side of the thick PCB board 1 when the thick PCB board 1 is electroplated, so that the thickness of the electroplated copper layer of the entire thick PCB board 1 is more uniform.

[0068] The beneficial effect brought by the above implementation method is that it can reduce the current on the side of the thick PCB board during electroplating of the thick PCB board, so that the thickness of the electroplated copper layer of the entire thick PCB board is more uniform.

[0069] In some implementations, when the thick PCB board 1 is a chemical tin-immersion board, a chemical nickel-gold-immersion board, or a chemical silver-immersion board, the difference between the aperture of the pre-drilled hole 11 and the aperture of the via hole 12 to be made is 0.1 mm.

[0070] During processing, after the pre-drilled holes 11 are produced on the thick PCB board 1, in order to protect the copper layer from oxidation and corrosion, a metal protection layer (such as a tin layer) is usually formed on the thick PCB board 1 before copper deposition.

[0071] When forming the tin layer on the thick PCB board 1, tin spraying treatment and chemical tin precipitation can be used. Tin spraying forms a tin film on the surface of the PCB board through the tin spraying process, which can effectively protect the copper layer from oxidation and corrosion, and also help to improve the reliability of welding. The tin spraying process can improve the heat resistance, corrosion resistance and welding performance of the PCB board, thereby improving the overall quality and reliability of the PCB board.

[0072] During processing, chemical tinning is to form a chemical tin layer, chemical nickel-gold layer or chemical silver layer in the via hole on the surface of the PCB board through chemical tinning. Due to different production processes, the thickness uniformity of the metal layer in the via hole of the chemical tinning board, chemical nickel-gold board or chemical silver board is better than that of the tin-spraying board.

[0073] During processing, since the uniformity of the metal layer thickness in the via holes of the chemical tin-immersion board, the chemical nickel-gold-immersion board or the chemical silver-immersion board is better than that of the tin-spraying board, a larger space needs to be reserved on the inner wall of the pre-drilled hole 11 of the tin-spraying board to offset the unevenness of the metal layer thickness on the inner wall of the pre-drilled hole 11. Therefore, the aperture of the pre-drilled hole 11 of the tin-spraying board can be smaller than the aperture of the pre-drilled hole 11 of the chemical tin-immersion board, the chemical nickel-gold-immersion board or the chemical silver-immersion board. While ensuring the production quality of the via holes 12 of the chemical tin-immersion board, the chemical nickel-gold-immersion board or the chemical silver-immersion board, the raw material cost and production cost required for the electroplating process can be saved.

[0074] For example, Figure 6 As shown, when the thick PCB board 1 is a chemical tin-immersion board, a chemical nickel-gold-immersion board or a chemical silver-immersion board, the difference between the aperture D1 of the pre-drilled hole 11 and the aperture D2 of the via hole 12 to be made can be 0.1 mm.

[0075] In some implementations, when the thick PCB board 1 is a tin-sprayed board, the difference between the aperture of the pre-drilled hole 11 and the aperture of the via hole 12 to be made is 0.15 mm.

[0076] During processing, the tin-sprayed board is a PCB board with a solder tin layer sprayed in the via holes. The thickness of the via holes of the tin-sprayed board is less uniform. Therefore, when the tin-sprayed board is produced, a larger gap can be reserved for the pre-drilled holes 11 of the tin-sprayed board. During electroplating, the uniformity and thickness of the copper layer in the via holes 12 of the tin-sprayed board can be improved by electroplating the copper layer.

[0077] For example, when the thick PCB board 1 is a tin-sprayed board, the difference between the aperture D1 of the pre-drilled hole 11 and the aperture D2 of the via hole 12 to be made may be 0.1 mm.

[0078] The beneficial effect brought about by the above-mentioned implementation method is that a smaller aperture of the pre-drilled hole 11 is reserved for the chemical tin-immersion board, the chemical nickel-gold-immersion board or the chemical silver-immersion board, while ensuring the production quality of the via 12 of the chemical tin-immersion board, the chemical nickel-gold-immersion board or the chemical silver-immersion board, it can save the raw material cost and production cost required for the electroplating process.

[0079] The beneficial effect brought by the above implementation method is that a larger aperture of the pre-drilled hole 11 is reserved for the tin-spraying plate, and the uniformity and thickness of the copper layer in the via hole 12 of the tin-spraying plate can be improved by electroplating the copper layer during electroplating.

[0080] In some implementations, when the thick PCB board 1 is a chemical tin-immersion board, a chemical nickel-gold-immersion board, or a chemical silver-immersion board, the depth of the expansion section 112 is 0.5 mm to 1.2 mm.

[0081] During processing, since the uniformity of the metal layer thickness in the via hole of the chemical tin-immersion board, chemical nickel-gold-immersion board or chemical silver-immersion board is better than that of the tin-spraying board, after the electroplating is completed, the copper layer uniformity at the mouth of the pre-drilled hole 11 of the chemical tin-immersion board, chemical nickel-gold-immersion board or chemical silver-immersion board is higher, and since the aperture difference between the pre-drilled hole 11 of the chemical tin-immersion board, chemical nickel-gold-immersion board or chemical silver-immersion board and the processed via hole 12 is smaller, the amount of metal gathered at the mouth of the pre-drilled hole 11 of the tin-spraying board due to the tip effect is smaller, so the chemical tin-immersion board, chemical nickel-gold-immersion board or chemical silver-immersion board The depth of the expansion section 112 of the board can be smaller than the depth of the expansion section 112 of the tin-spraying board, which can reduce the total amount of metal layer that needs to be removed at the mouth of the expansion section 112 of the chemical tin-immersion board, the chemical nickel-gold-immersion board or the chemical silver-immersion board, and can ensure that the metal layer thickness at the mouth of the via hole of the chemical tin-immersion board, the chemical nickel-gold-immersion board or the chemical silver-immersion board meets the requirements. While ensuring the production quality of the copper layer on the inner side wall of the via hole of the chemical tin-immersion board, the chemical nickel-gold-immersion board or the chemical silver-immersion board, the electroplating production cost during the production of the chemical tin-immersion board, the chemical nickel-gold-immersion board or the chemical silver-immersion board is saved.

[0082] For example, Figure 4 As shown, when the thick PCB board 1 is a chemical tin-immersion board, a chemical nickel-gold-immersion board or a chemical silver-immersion board, the depth h of the expansion section 112 is 0.5 mm to 1.2 mm.

[0083] In some implementations, when the thick PCB board 1 is a tin-sprayed board, the depth of the expansion section 112 is 1.2 mm to 1.8 mm.

[0084] Structurally, since the uniformity of the metal layer thickness in the via hole of the chemical tin-immersion board, chemical nickel-gold-immersion board or chemical silver-immersion board is better than that of the tin-spraying board, the uniformity of the copper layer at the mouth of the pre-drilled hole 11 of the tin-spraying board is poor after the electroplating is completed, and since the difference in aperture between the pre-drilled hole 11 of the tin-spraying board and the processed via 12 is larger, the amount of metal gathered at the mouth of the pre-drilled hole 11 of the tin-spraying board due to the tip effect is larger, and therefore the depth of the expansion section 112 of the tin-spraying board can be greater than the depth of the expansion section 112 of the chemical tin-spraying board, chemical nickel-gold-immersion board or chemical silver-spraying board, which can further ensure that the uniformity of the metal layer at the mouth of the via hole of the tin-spraying board meets the requirements, and can ensure the production quality of the via hole of the tin-spraying board.

[0085] For example, Figure 4As shown, when the thick PCB board 1 is a hot air solder leveling (HASL) board, the depth h of the hole expansion section 112 is 1.2 mm to 1.8 mm. The depth h of the hole expansion section 112 of the HASL board can be greater than that of the electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board.

[0086] The beneficial effects brought by the above implementation method are as follows: while ensuring the production quality of the copper layer on the inner wall of the via and the copper layer at the via opening of the electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board, the electroplating production cost during the production of the electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board is saved.

[0087] The beneficial effects brought by the above implementation method also lie in that the depth of the hole expansion section of the HASL board can be greater than that of the electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board, which can further ensure that the uniformity of the metal layer at the opening of the via of the HASL board meets the requirements and can ensure the production quality of the via of the HASL board.

[0088] In some implementation methods, when the thick PCB board 1 is an electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board, the opening angle of the hole expansion section 112 is 10° to 13°.

[0089] Structurally, since the difference in aperture between the pre-drilled hole 11 and the processed via 12 of the electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board is smaller, and the depth of the hole expansion section 112 of the electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board can be smaller than that of the HASL board, the amount of metal aggregated at the opening of the pre-drilled hole 11 of the HASL board due to the tip effect is smaller. Therefore, the opening angle of the hole expansion section 112 of the electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board can be smaller than that of the hole expansion section 112 of the HASL board, which can reduce the total amount of metal layer to be removed at the opening of the hole expansion section 112 of the electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board, and can ensure that the thickness of the metal layer at the opening of the via of the electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board meets the requirements. While ensuring the production quality of the copper layer on the inner wall of the via of the electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board, the electroplating production cost during the production of the electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board is saved.

[0090] Exemplarily, as Figure 4 shown, when the thick PCB board 1 is an electroless tin plating board, electroless nickel immersion gold board, or electroless silver plating board, the opening angle α of the hole expansion section 112 is 10° to 13°.

[0091] In some implementation methods, when the thick PCB board 1 is a HASL board, the opening angle of the hole expansion section 112 is 13° to 18°.

[0092] Structurally, since the uniformity of the metal layer thickness in the via hole of the chemical tin-immersion board, chemical nickel-gold-immersion board or chemical silver-immersion board is better than that of the tin-spraying board, the uniformity of the copper layer at the mouth of the pre-drilled hole 11 of the tin-spraying board is poor after the electroplating is completed, and since the aperture difference between the pre-drilled hole 11 of the tin-spraying board and the processed via 12 is larger, the amount of metal gathered at the mouth of the pre-drilled hole 11 of the tin-spraying board due to the tip effect is larger, and therefore the opening angle of the expansion section 112 of the tin-spraying board can be larger than the opening angle of the expansion section 112 of the tin-spraying board, which can further ensure that the uniformity of the metal layer at the mouth of the via hole of the tin-spraying board meets the requirements, and can ensure the production quality of the via hole of the tin-spraying board.

[0093] For example, Figure 4 As shown, when the thick PCB board 1 is a tin-sprayed board, the opening angle α of the expansion section 112 is 13° to 18°.

[0094] The beneficial effect brought about by the above-mentioned implementation method is that the opening angle of the expansion section of the chemical tin-immersion board, the chemical nickel-gold-immersion board or the chemical silver-immersion board can be smaller than the opening angle of the expansion section of the tin-spraying board, while ensuring the production quality of the copper layer on the inner side wall of the via and the copper layer at the via mouth of the chemical tin-immersion board, the chemical nickel-gold-immersion board or the chemical silver-immersion board, while saving the electroplating production cost during the production of the chemical tin-immersion board, the chemical nickel-gold-immersion board or the chemical silver-immersion board.

[0095] The beneficial effect brought about by the above-mentioned implementation method is that the opening angle of the expansion section of the tin-spraying plate can be larger than the opening angle of the expansion section of the tin-spraying plate, which can further ensure that the uniformity of the metal layer at the mouth of the via hole of the tin-spraying plate meets the requirements and ensure the production quality of the via hole of the tin-spraying plate.

[0096] An embodiment of the present application provides a PCB board, and the via holes of the PCB board are manufactured by the above method.

[0097] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for making vias in a thick PCB, characterized in that: The method comprises: Processing a pre-drilled hole (11) penetrating a thick PCB board (1); wherein the diameter of the pre-drilled hole (11) is larger than the diameter of the via hole (12) to be produced, and the designed thickness of the thick PCB board (1) is larger than 5 mm; After copper deposition and full-board electroplating are performed on a thick PCB board (1), a primary copper layer (111) is formed in the pre-drilled hole (11), and the hole is expanded from the end of the pre-drilled hole (11) to the middle of the pre-drilled hole (11) by controlled depth drilling to obtain an expanded hole section (112); Performing secondary full-board electroplating on the thick PCB board (1) to thicken the copper layer in the pre-drilled hole (11), forming a secondary copper layer (113) in the pre-drilled hole (11), and obtaining a completed via hole (12); The current density of the first full-plate electroplating is greater than that of the second full-plate electroplating, and the electroplating time of the first full-plate electroplating is less than that of the second full-plate electroplating; The expansion section (112) is in a tapered structure that decreases from the end of the pre-drilled hole (11) toward the middle of the pre-drilled hole (11); When the thick PCB board (1) is a chemical tin-immersion board, a chemical nickel-gold-immersion board or a chemical silver-immersion board, the difference between the aperture of the pre-drilled hole (11) and the aperture of the via hole (12) to be made is 0.1 mm; When the thick PCB board (1) is a tin-sprayed board, the difference between the diameter of the pre-drilled hole (11) and the diameter of the via hole (12) to be made is 0.15 mm; When the thick PCB board (1) is a chemical tin-immersion board, a chemical nickel-gold-immersion board or a chemical silver-immersion board, the depth of the expansion section (112) is 0.5 mm to 1.2 mm; When the thick PCB board (1) is a tin-sprayed board, the depth of the hole expansion section (112) is 1.2 mm to 1.8 mm; When the thick PCB board (1) is a chemical tin-immersion board, a chemical nickel-gold-immersion board or a chemical silver-immersion board, the opening angle of the expansion section (112) is 10° to 13°; When the thick PCB board (1) is a tin-sprayed board, the opening angle of the hole expansion section (112) is 13° to 18°.

2. The method for making vias in a thick PCB board as claimed in claim 1, characterized in that: The design thickness of the thick PCB board (1) is 6.0 mm ± 10%, the aperture design tolerance of the via hole (12) is ± 0.03 mm, and the minimum copper thickness of the inner wall of the via hole (12) is ≥ 30 μm.

3. The method for making vias in a thick PCB board as claimed in claim 2, characterized in that: The parameters for the first full-plate electroplating are designed to be 90 minutes of electroplating and a current density of 1.7ASD; the parameters for the second full-plate electroplating are designed to be 150 minutes of electroplating and a current density of 1.2ASD; The copper sulfate concentration for the first full-board electroplating and the second full-board electroplating is 50-60g / L, and the sulfuric acid concentration is 120-130ml / L.

4. The method for making vias in a thick PCB board as claimed in claim 3, characterized in that: During the primary full-board electroplating and the secondary full-board electroplating, metal electroplating edge strips for conducting current to the thick PCB board (1) are clamped on a set of opposite edges of the thick PCB board (1).

5. A PCB board, characterized in that: The via holes of the PCB board are manufactured by the method according to any one of claims 1 to 4.

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