Circuit board plating processing method
By forming a complete electrical conductive structure on the circuit board through electroplating bridging and copper paste filling processes, the problems of complexity and instability in the processing of through holes in circuit boards in the prior art are solved, and the effects of simplifying the process and improving reliability are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- ZHUHAI FOUNDER TECH HI DENSITY ELECTRONICS
- Filing Date
- 2023-09-05
- Publication Date
- 2026-07-03
Smart Images
Figure CN117015154B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of electroplating technology, and more particularly to a method for electroplating circuit boards. Background Technology
[0002] With the technological development of terminal electronic products, in order to meet the requirements of product performance improvement and personalized design, circuit boards are gradually developing towards ultra-thinness and denser conductive structures.
[0003] In the prior art, through holes are often made on the circuit board. Electroplating and resin plugging are performed on the through holes to achieve electrical connection of the circuits on both sides of the circuit board. After the resin plugging is completed, the circuit board needs to be brushed and polished.
[0004] However, the through-hole structure of the circuit board in the prior art has a complex processing flow, and the stability and reliability of the through-hole structure formed by the process are insufficient. Summary of the Invention
[0005] In view of the above problems, this application provides a circuit board electroplating process that simplifies the process and improves the stability and reliability of the formed through-hole structure.
[0006] To achieve the above objectives, this application provides the following technical solution:
[0007] This application provides a method for electroplating circuit boards, including:
[0008] Drill through holes along the thickness direction of the circuit board;
[0009] Copper layers are plated on both sides of the circuit board in the thickness direction and on the walls of the through holes.
[0010] Electroplating bridging is performed in the through hole to form a connecting copper layer at the middle position of the through hole along the extension direction. The connecting copper layer divides the through hole into two independent blind holes along the extension direction.
[0011] Copper paste is filled into the cavities of the two blind holes to form a complete electrical conductive structure inside the through holes;
[0012] A copper layer is then plated onto the surface of the circuit board to cover the openings of the two blind holes, forming a cap.
[0013] The circuit board electroplating method provided in this application, through the combined use of electroplating bridging and copper paste filling processes, can form a complete electrically conductive structure inside the through-holes. Compared with the resin plugging process in the prior art, this application simplifies the processing flow, shortens processing time, and reduces processing costs. Furthermore, the circuit board electroplating method provided in this application improves the stability and reliability of the formed through-hole structure; the formed through-hole structure has the advantages of good conductivity and high connection strength, which can improve the product's ability to withstand extreme conditions. Therefore, the circuit board electroplating method provided in this application simplifies the processing flow and improves the stability and reliability of the formed through-hole structure.
[0014] In one possible implementation, after drilling through-holes on the circuit board, the following steps are also included:
[0015] A hole inspection machine is used to check the accuracy and alignment of the through holes.
[0016] By using a hole inspection machine to inspect the positions of through holes, the yield rate of the manufactured circuit boards can be improved.
[0017] In one possible implementation, the electroplating bridging process in the through-hole specifically includes:
[0018] Pulse electroplating was used for electroplating bridging, and the current intensity, chemical exchange rate and copper ion concentration of the pulse electroplating process were adjusted to control the forming time of the copper bonding layer.
[0019] In this way, by adjusting the current intensity, chemical exchange rate, and copper ion concentration, the required copper bonding layer can be obtained within a set time for subsequent processing.
[0020] In one possible implementation, the process of filling the cavities of the two blind holes with copper paste specifically includes:
[0021] A vacuum plugging process is used to fill the cavity of the blind via with copper paste, and the copper paste at the via opening does not extend beyond the two sides of the circuit board along the thickness direction.
[0022] In this way, the copper paste at the opening does not extend beyond the sides of the board, which reduces the processing difficulty of the circuit board and reduces processing time and costs.
[0023] In one possible implementation, the copper paste filling volume accounts for 85%-95% of the cavity volume of the blind via.
[0024] This ensures that the copper paste filling volume ratio in the blind via cavity meets the requirements, and also ensures that the copper paste will not exceed the two sides of the circuit board after thermal expansion.
[0025] In one possible implementation, after further plating a copper layer on the surface of the circuit board, the following steps are also included:
[0026] The copper layer thickness on the circuit board is reduced by using a whole-board copper reduction process, and the depression of the copper layer at the cap is eliminated to make the copper layer thickness on the circuit board uniform.
[0027] In this way, by using the whole-board copper reduction process to reduce the thickness of the copper layer on the circuit board, the quality of subsequent circuit board processing can be guaranteed.
[0028] In one possible implementation, after filling the cavities of the two blind holes with copper paste, the process also includes brushing and cleaning the surface of the circuit board.
[0029] In this way, brushing and cleaning the surface of the circuit board can prevent foreign objects on the circuit board surface from affecting the quality of the circuit board processing.
[0030] In one possible implementation, the process of further plating a copper layer on the surface of the circuit board specifically includes:
[0031] Obtain the thickness of the copper paste along the direction perpendicular to the circuit board surface;
[0032] The electroplating process is determined based on the thickness of the copper paste along the direction perpendicular to the circuit board surface, so that the openings are covered with a copper layer that meets the thickness requirements.
[0033] Thus, the circuit board electroplating method provided in this application can select different electroplating processes for different copper paste thicknesses to meet processing requirements, and has the advantage of strong adaptability.
[0034] In one possible implementation, the target plating thickness of the copper layer is 5-7 μm during the process of plating copper layers on both sides of the circuit board and the walls of the vias.
[0035] This reduces processing time and provides a copper substrate with the required thickness for subsequent electroplating bridging processes.
[0036] In one possible implementation, the thickness of the circuit board is no greater than 0.25 mm; the diameter of the through hole is no greater than 0.20 mm.
[0037] After the circuit board is manufactured, the thickness of the copper layer on the hole wall shall not be less than 15μm, and the thickness of the copper layer on the circuit board surface shall not be less than 60μm.
[0038] In this way, the copper layer thickness is within this range, which ensures the quality of the circuit board.
[0039] The structure of this application, as well as its other inventive objectives and beneficial effects, will become more apparent and understandable through a description of the specific embodiments in conjunction with the accompanying drawings. Attached Figure Description
[0040] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0041] Figure 1 A flowchart of a circuit board electroplating process provided in an embodiment of this application;
[0042] Figure 2 This is a schematic diagram of a circuit board after drilling, provided in an embodiment of this application.
[0043] Figure 3 This is a schematic diagram of a circuit board after copper plating, provided in an embodiment of this application.
[0044] Figure 4 This is a schematic diagram of the circuit board after electroplating bridging, provided in an embodiment of this application.
[0045] Figure 5 This is a schematic diagram of a circuit board after copper paste has been applied, as provided in an embodiment of this application.
[0046] Figure 6 This is a schematic diagram of the circuit board after the cap has been formed, as provided in the embodiments of this application;
[0047] Figure 7 This is a schematic diagram of the circuit board after copper reduction in an embodiment of this application.
[0048] Explanation of reference numerals in the attached figures:
[0049] 100 - Circuit board;
[0050] 110 - Through hole;
[0051] 111 - Hole wall;
[0052] 112-Blind hole;
[0053] 113 - Orifice;
[0054] 120-board surface;
[0055] 200-Copper layer;
[0056] 210 - Block;
[0057] 220 - Depression;
[0058] 300 - Connecting copper layer;
[0059] 400-Copper paste. Detailed Implementation
[0060] Printed circuit boards (PCBs) are fundamental components of various electronic products. As a key product in electronic systems, PCBs are used in almost all electronic products, and their quality directly affects the quality of the electronic products. With the technological development of end-product electronic products, in order to meet the requirements of improved product performance and personalized design, PCBs are gradually developing towards ultra-thinness and denser conductive structures. In existing technologies, through-holes are often fabricated on thin boards. Electroplating and resin plugging are then performed on these through-holes to achieve electrical connectivity between the circuitry on both sides of the PCB. After resin plugging, the PCB still needs to be brushed and polished.
[0061] For example, the prior art provides a circuit board manufacturing process including the following steps: drilling holes to drill through holes on the circuit board that need to be filled with resin; chemical copper plating to plate copper on the walls of the drilled holes so that the layers can conduct; resin filling to fill the holes with insulating resin; post-curing to completely cure the resin after filling the holes at high temperature; and brushing to smooth out the excess resin in the holes using a non-woven brush wheel or sanding belt.
[0062] However, the processing of through-holes in existing circuit boards is complex. When filling thin boards with resin, resin is prone to falling out of the through-holes. In addition, when brushing the resin on the surface of thin boards, board curling and jamming are likely to occur. Furthermore, there are also quality problems such as incomplete brushing and inconsistent expansion and contraction of the board surface. As a result, the stability and reliability of the through-hole structure formed by the process are insufficient.
[0063] To address the aforementioned problems, this application provides a circuit board electroplating method. A copper layer is plated on both sides of the circuit board and on the walls of through-holes. Then, electroplating bridging is performed in the through-holes to form two independent blind holes. Next, copper paste is filled into the cavities of the two blind holes to create a complete electrical conductive structure inside the through-holes. Finally, a cap is formed by electroplating to seal the copper paste within the cavities. Thus, by combining the electroplating bridging process and the copper paste filling process, a complete electrical conductive structure can be formed inside the through-holes, simplifying the processing flow and shortening the processing time. Furthermore, the circuit board electroplating method provided in this application does not require resin plugging, thereby improving the stability and reliability of the formed through-hole structure.
[0064] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0065] The technical solution of this application and how it solves the above-mentioned technical problems are described in detail below with specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.
[0066] The following combination Figures 1 to 7 The electroplating process for circuit boards provided in the embodiments of this application will be described in detail.
[0067] This application provides a method for electroplating circuit boards, such as... Figure 1 As shown in the figure, the flowchart illustrates the circuit board electroplating process, which includes the following steps:
[0068] S100: Drill through holes in the circuit board along the thickness direction.
[0069] Specifically, such as Figure 2 As shown, the circuit board 100 has through holes 110 along the thickness direction, and the through holes 110 can connect the two side surfaces 120 of the circuit board 100 along the thickness direction; in addition, the through holes 110 can be drilled on the circuit board 100 by mechanical drilling.
[0070] S200: Copper layers are plated on both sides of the circuit board in the thickness direction and on the walls of the through holes.
[0071] Specifically, such as Figure 3 As shown, the circuit board 100 with through-holes 110 undergoes a first horizontal electroplating process, and a copper layer 200 is plated on both sides 120 of the circuit board 100 and on the hole walls 111 of the through-holes 110 using a chemical copper plating method. The presence of the copper layer 200 provides a substrate for subsequent processing. It should be noted that the presence of the copper substrate can improve the efficiency of subsequent electroplating bridging.
[0072] S300: Electroplating bridging is performed in the through hole to form a connecting copper layer at the middle position of the through hole along the extension direction, which divides the extension direction of the through hole into two independent blind holes.
[0073] Specifically, such as Figure 4As shown, based on the copper layers 200 on both sides of the plate 120 and the copper layers 200 on the hole walls 111, an electroplating bridging process can be used to form a connecting copper layer 300 in the through hole 110, and to form two independent blind holes 112. The basic principle of pulse electroplating bridging is as follows: using pulsed current to provide energy, metal ions are ionized from the electroplating solution and become charged under the action of the pulsed current; these charged metal ions move along the direction of the current and approach the copper layer surface; when the charged metal ions approach the copper layer surface, they are adsorbed onto the copper layer surface by Coulomb force and form a metal film; during the adsorption process of metal ions, some ions form a bridging structure on the copper layer surface, i.e., the connecting copper layer 300 in the figure; the bridging structure can increase conductivity and improve the quality and efficiency of electroplating.
[0074] S400: Copper paste is filled into the cavities of two blind holes to form a complete electrical conductive structure inside the through hole.
[0075] Specifically, such as Figure 5 As shown, after copper paste 400 is inserted into the cavities of the two independent blind holes 112, the copper paste 400 in the two cavities and the connecting copper layer 300 in the middle of the through hole 110 can become one, and a complete electrical conductive structure is formed inside the through hole 110.
[0076] S500: A copper layer is plated on the surface of the circuit board to cover the openings of the two blind holes, forming a cap.
[0077] Specifically, such as Figure 6 As shown, the circuit board 100 with copper paste 400 is subjected to a second horizontal electroplating. The cap 210 formed by electroplating can cover the openings 113 of the two blind holes 112, thereby sealing the copper paste 400 in the cavity of the blind holes 112. In addition, the second horizontal electroplating can be used to improve the flatness of the copper layer 200 on the board surface 120.
[0078] Therefore, the circuit board electroplating method provided in this application, through the combined use of electroplating bridging and copper paste filling processes, can form a complete electrically conductive structure inside the through-hole 110. Compared with the resin plugging process in the prior art, this application simplifies the processing flow, shortens the processing time, and reduces processing costs. Furthermore, since the circuit board electroplating method provided in this application does not require resin plugging or resin brushing, the stability and reliability of the formed through-hole structure are improved. The through-hole structure formed by the combined use of electroplating bridging and copper paste filling processes has the advantages of good conductivity and high connection strength, which can improve the product's ability to withstand extreme conditions. In addition, the processing method provided in this application has good overall controllability, which can improve the uniformity of products in the same batch and ensure product quality. Therefore, the circuit board electroplating method provided in this application simplifies the processing flow and improves the stability and reliability of the formed through-hole structure.
[0079] In this embodiment of the application, after drilling through holes 110 on the circuit board 100, the method further includes:
[0080] A hole inspection machine is used to check the accuracy and alignment of the through-hole positions. The accuracy and alignment of the through-hole positions directly affect the quality of the produced circuit board 100. If the accuracy and alignment of the through-hole positions do not meet the requirements, it will cause quality defects in the circuit board 100. By setting up this system and using a hole inspection machine to check the through-hole positions, the yield rate of the processed circuit board 100 can be improved.
[0081] In the embodiments of this application, such as Figure 4 As shown, the electroplating bridging process in the through-hole 110 specifically includes: using a pulse electroplating process for electroplating bridging, and adjusting the current intensity, chemical exchange rate, and copper ion concentration of the pulse electroplating process to control the formation time of the connecting copper layer 300. It should be noted that during the pulse electroplating process, factors such as current intensity, chemical exchange rate, and copper ion concentration all affect the formation time of the connecting copper layer 300. By adjusting the current intensity, chemical exchange rate, and copper ion concentration, the required connecting copper layer 300 can be obtained within a set time for subsequent processing.
[0082] In the embodiments of this application, such as Figure 5As shown, the process of filling the cavities of the two blind vias 112 with copper paste specifically includes: filling the cavities of the blind vias 112 with copper paste 400 using a vacuum via-filling process. Filling the cavities of the blind vias 112 with copper paste 400 in a vacuum environment avoids contact between the copper paste 400 and air, thus ensuring the reliability of the copper paste filling process. Furthermore, the copper paste 400 at the via opening 113 does not extend beyond the two side surfaces 120 of the circuit board 100 along the thickness direction; if the copper paste 400 at the via opening 113 extends beyond the side surfaces 120, it needs to be brushed and polished. The hardened copper paste 400 has a high hardness, increasing the processing difficulty. This design, ensuring that the copper paste 400 at the via opening 113 does not extend beyond the two side surfaces 120, reduces the processing difficulty of the circuit board 100, and reduces processing time and costs.
[0083] Specifically, such as Figure 5 As shown, the filling volume of copper paste 400 accounts for 85%-95% of the cavity volume of blind via 112. The copper paste 400 in the cavity of blind via 112 will expand when heated. If the proportion of the filling volume of copper paste 400 in the cavity volume of blind via 112 is too large, it will cause the copper paste 400 to expand beyond the side surfaces 120 of the circuit board 100 after heating. This setting, with the filling volume ratio of copper paste 400 within the range of 85%-95%, ensures that the filling volume ratio of copper paste 400 in the cavity of blind via 112 meets the requirements, while also ensuring that the copper paste 400 does not expand beyond the side surfaces 120 of the circuit board 100 after heating.
[0084] Furthermore, such as Figure 7 As shown, after further plating a copper layer 200 on the surface 120 of the circuit board 100, the process further includes: using a whole-board copper reduction process to reduce the thickness of the copper layer 200 on the circuit board surface, and eliminating the recess 220 of the copper layer 200 at the cap 210 on the circuit board surface, so as to make the thickness of the copper layer 200 on the circuit board surface uniform. Figure 6 As shown, since the copper paste 400 at the orifice 113 does not extend beyond the two side surfaces 120 of the circuit board 100 along the thickness direction, after the copper layer 200 plated on the side surface 120 of the circuit board 100 covers the orifices 113 of the two blind holes 112, a depression 220 will appear in the copper layer 200 at the cap 210, thus affecting the flatness of the copper layer 200 on the side surface 120. With this setting, after reducing the thickness of the copper layer 200 on the circuit board surface using the whole board copper reduction process, the subsequent processing quality of the circuit board 100 can be guaranteed.
[0085] In this embodiment, after filling the cavities of the two blind holes 112 with copper paste, the method further includes brushing and cleaning the surface of the circuit board 100. After being processed by different manufacturing processes, the surface of the circuit board 100 may retain some foreign matter, which can affect the cleanliness of the circuit board 100 and thus the subsequent processing quality. This design, by brushing and cleaning the surface of the circuit board 100, can prevent the foreign matter on the surface of the circuit board 100 from affecting the processing quality of the circuit board 100.
[0086] In this embodiment, the process of further plating a copper layer 200 on the surface 120 of the circuit board 100 specifically includes: obtaining the thickness of the copper paste 400 along the direction perpendicular to the circuit board surface; and then, determining the electroplating process based on the thickness of the copper paste 400 along the direction perpendicular to the circuit board surface, so that the opening 113 is covered by a copper layer 200 that meets the thickness requirements. It should be noted that different electroplating processes need to be used for different copper paste 400 thicknesses to obtain a copper layer 200 that meets the thickness requirements. With this configuration, the circuit board electroplating processing method provided in this application can select different electroplating processes for different copper paste 400 thicknesses to meet processing requirements, and has the advantage of strong adaptability.
[0087] In the embodiments of this application, such as Figure 3 As shown, during the process of plating copper layer 200 on the two side surfaces 120 of the circuit board 100 and the hole walls 111 of the through hole 110, the target plating thickness of copper layer 200 is 5-7 μm. With this setting, when the target plating thickness of copper layer 200 is within the range of 5-7 μm, it can reduce processing time and provide a copper layer substrate that meets the thickness requirements for subsequent electroplating bridging processes.
[0088] In this embodiment, the thickness of the circuit board 100 is no greater than 0.25 mm; the diameter of the through hole 110 is no greater than 0.20 mm; and the total number of holes on the circuit board 100 reaches 200,000 or more. Additionally, as... Figure 7 As shown, after the circuit board 100 is processed, the thickness of the copper layer 200 on the hole wall 111 is not less than 15μm, and the thickness of the copper layer 200 on the surface of the circuit board is not less than 60μm. With this setting, the quality of the processed circuit board 100 can be guaranteed when the thickness of the copper layer 200 is within this range.
[0089] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.
[0090] The devices or elements referred to in this application or implied herein must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as limiting this application. In the description of this application, "a plurality of" means two or more, unless otherwise precisely specified.
[0091] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.
[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
Claims
1. A method of electroplating a circuit board, comprising: include: Drill through holes in the circuit board along its thickness direction; A copper layer is plated on both sides of the circuit board in the thickness direction and on the wall of the through hole; wherein the target plating thickness of the copper layer is 5-7 μm; Electroplating bridging is performed in the through hole to form a connecting copper layer at the middle position of the through hole along the extension direction. The connecting copper layer divides the through hole into two independent blind holes along the extension direction. The electroplating bridging is performed using a pulse electroplating process, and the current intensity, chemical exchange rate and copper ion concentration of the pulse electroplating process are adjusted to control the forming time of the connecting copper layer. Copper paste is filled into the cavities of the two blind vias to form a complete electrical conductive structure inside the vias. A vacuum via-filling process is used to fill the cavities of the blind vias with copper paste, ensuring that the copper paste at the via opening does not extend beyond the thickness-direction sides of the circuit board. Furthermore, the volume of the copper paste filling occupies 85%-95% of the cavity volume of the blind vias. A copper layer is further plated on the surface of the circuit board so that the openings of the two blind holes are covered by the copper layer, and the copper layer covering the openings forms a cap; wherein, the thickness of the copper paste along the direction perpendicular to the surface of the circuit board is obtained; based on the thickness of the copper paste along the direction perpendicular to the surface of the circuit board, an electroplating process is determined so that the openings are covered by the copper layer. After the copper layer plated on the surface of the circuit board covers the openings of the two blind holes, there will be a depression in the copper layer at the cap. The copper layer thickness on the surface of the circuit board is reduced by the whole board copper reduction process, and the depression in the copper layer on the surface of the circuit board at the cap is eliminated, so that the copper layer thickness on the surface of the circuit board is uniform. The thickness of the copper layer on the surface of the circuit board is not less than 60μm.
2. The circuit board plating process of claim 1, wherein, After drilling the through-hole on the circuit board, the method further includes: The accuracy and alignment of the through holes are inspected using a hole inspection machine.
3. The circuit board plating process of claim 1 or 2, wherein, After filling the cavities of the two blind holes with copper paste, the process further includes brushing and cleaning the surface of the circuit board.
4. The electroplating method according to claim 1 or 2, wherein The thickness of the circuit board is no greater than 0.25 mm; the diameter of the through hole is no greater than 0.20 mm; After the circuit board is manufactured, the thickness of the copper layer on the hole wall is not less than 15μm.