Electroplating baffle capable of establishing uniform electric field
By using a differentiated aperture design for the cathode baffle during the electroplating process, the electric field distribution is actively corrected, solving the problem of uneven coating during electroplating and achieving a highly efficient and uniform electroplating effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHENZHEN TIANQI SCIENCE & TECHNOLOGY CO LTD
- Filing Date
- 2026-03-19
- Publication Date
- 2026-06-05
AI Technical Summary
In existing electroplating processes, uneven coating is caused by the edge effect of the electric field. Traditional baffle adjustments are cumbersome and have limited effectiveness.
Design a cathode baffle with a high-aperture-ratio regular polygon array in the central region and a low-aperture-ratio or small-diameter circular array in the edge region. The electric field distribution is actively corrected by the differentiated aperture structure to form a uniform electric field.
It significantly reduces the coefficient of variation of coating thickness to below 10%, improves electroplating efficiency, and ensures coating uniformity and electroplating quality.
Smart Images
Figure CN122147484A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of electrochemical processing technology, and in particular to an electroplating baffle capable of establishing a uniform electric field. Background Technology
[0002] In the electroplating process, the electroplating baffle is a special non-conductive component installed in the electroplating tank. It is mainly used to precisely control the current distribution and ion flow field, suppress excessive coating thickness and scorching caused by sharp and edge effects, and protect specific areas of the workpiece from electroplating. It is a low-cost process tool to improve the uniformity of the coating.
[0003] During electroplating, the electric field strength affects the uniformity of the coating, and the distribution of the electric field strength directly determines the deposition rate and thickness of metal ions on the surface of the workpiece. In the electroplating tank, the electric field distribution between the workpiece and the anode metal source is often uneven. Especially when the workpiece has a complex shape, the electric field strength at the edges and tips is significantly enhanced, leading to concentrated current density and problems such as excessively thick coating, scorching, or roughness.
[0004] To address the uneven electric field distribution caused by edge effects, electrode geometry, and complex workpiece structures during electroplating, the industry commonly employs a cathode baffle installed between the anode and cathode in the electroplating tank. Existing electroplating baffles are typically thin anode baffles with a uniform array of through-holes. Their working principle is to passively and generally reduce local electric field strength by physically blocking some electric field lines. In practical applications, this uniform baffle structure often fails to accurately match the actual electric field distortion pattern. The process involves an empirical adjustment: first, a trial plating is performed to measure the coating thickness distribution; then, based on the measurement results, in areas with excessively strong electric fields, some holes in the baffle are manually sealed to increase shielding; next, another trial plating is performed and measurements are taken, repeating this adjustment process until a relatively acceptable uniformity is achieved. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide a cathode baffle with a zoned and differentiated opening structure, which can actively correct the electric field distribution between the anode and cathode, thereby establishing a highly uniform electric field on the cathode surface and effectively solving the edge effect problem in the electroplating process.
[0006] The above-mentioned objective of this invention is achieved through the following technical solutions:
[0007] An electroplating baffle capable of establishing a uniform electric field, characterized in that it comprises:
[0008] A cathode baffle is configured to be arranged in parallel between the anode and cathode of the electroplating tank;
[0009] The area of the cathode baffle is larger than the effective electroplating area of the cathode;
[0010] The cathode baffle is provided with multiple openings that penetrate its thickness;
[0011] The cathode baffle has a first type of aperture array in its central region and a second type of aperture array in its edge region. The first type of aperture and the second type of aperture are different in shape, size and / or distribution density, so that the cathode baffle can correct the electric field lines from the anode to the cathode and make the electric field distribution reaching the cathode surface more uniform.
[0012] As a specific embodiment of an electroplating baffle that can establish a uniform electric field disclosed in this invention, the opening shape in the first type of opening array is a regular polygon.
[0013] As a specific embodiment of an electroplating baffle that can establish a uniform electric field disclosed in this invention, the regular polygon is a regular hexagon, and the first type of opening array is arranged in a honeycomb pattern.
[0014] As a specific embodiment of an electroplating baffle capable of establishing a uniform electric field disclosed in this invention, the opening shape in the second type of opening array is circular.
[0015] As a specific embodiment of an electroplating baffle that can establish a uniform electric field disclosed in this invention, the distribution density of the second type of openings is greater than the distribution density of the first type of openings in the central region.
[0016] As a specific embodiment of an electroplating baffle that can establish a uniform electric field disclosed in this invention, the distribution density of the second type of openings in the edge region decreases in a gradient from the side closer to the center region to the outside further away from the center region.
[0017] As a specific embodiment of an electroplating baffle that can establish a uniform electric field disclosed in this invention, the aperture of the second type of opening is adjustable to precisely balance the electric field intensity between the cathode edge and the central region.
[0018] As a specific embodiment of an electroplating baffle capable of establishing a uniform electric field disclosed in this invention, the area of the cathode baffle is 5% to 20% larger than the effective electroplating area of the cathode, and the distance between the cathode baffle and the cathode is set to 20mm-200mm.
[0019] As a specific embodiment of an electroplating baffle capable of establishing a uniform electric field disclosed in this invention, the cathode baffle has a thickness of 15 mm to 200 mm, and this thickness is configured to provide effective correction and guidance for curved electric field lines passing through its openings near the cathode.
[0020] As a specific embodiment of an electroplating baffle that can establish a uniform electric field disclosed in this invention, the cathode baffle is installed in the electroplating bath in a swingable or rotatable manner through a supporting member.
[0021] In summary, the present invention has at least one of the following beneficial technical effects:
[0022] 1. This invention provides a cathode baffle with a "center-edge" partitioned differential opening structure, which actively intervenes in and reshapes the electric field between the anode and cathode from a physical structure perspective. This design abandons the cumbersome adjustment method of traditional "trial and error-sealing". Through the synergistic effect of the first type of opening array with high opening ratio in the central region and the second type of opening array with low opening ratio or small aperture in the edge region, the curved electric field lines are intelligently corrected, and the electric field intensity distribution reaching the cathode surface is flattened. Its direct effect is to stably reduce the coefficient of variation of the coating thickness from the industry common of more than 15% to less than 10%, or even reach an extremely high level of less than 5%.
[0023] 2. The central region of the present invention preferably adopts a regular hexagonal honeycomb-shaped perforation array. This structure ensures the mechanical strength of the baffle while achieving the maximum perforation area ratio, forming an almost "transparent" electric field channel, allowing the electric field lines in the central region to pass through vertically and efficiently with almost no loss. The edge region preferably adopts circular perforations. Its axisymmetric characteristics ensure that inclined electric field lines from different directions are consistently and effectively constrained and guided. This differentiated design of shape, size and / or distribution density enables a simple physical baffle to have the spatial electric field intelligent control capability like an "adjustable grating", which maintains the high-efficiency production in the central region and precisely suppresses the excessively strong electric field in the edge region.
[0024] 3. The area of the cathode baffle of this invention is 5%-20% larger than the effective area of the cathode, ensuring complete coverage and control of the cathode edge projection area most prone to electric field distortion. The baffle has a predetermined thickness of 15mm to 200mm, providing sufficient path length for the obliquely incident electric field lines, effectively attenuating the component perpendicular to the hole wall, thereby forcing the direction of the emitted electric field lines to be more consistent with the hole axis, realizing the "from the surface to the inside" depth correction of the curved electric field lines. The adjustable range of these parameters also makes the device highly adaptable to the process and can be optimized according to different electroplating tank conditions.
[0025] 4. This cathode baffle effectively and rationally distributes the electric field intensity between the cathode and anode, effectively avoiding the previous electroplating areas where only some electric field lines were densely or sparsely distributed. Therefore, under the same electroplating time and rectifier current input, the electroplating efficiency can be effectively improved, and the overall electroplated metal thickness of the cathode plate area is significantly greater than that of the conventional baffle plugging method. When the plugging area is too large in a local area, the electric field strength reaching the cathode will be lost. Attached Figure Description
[0026] Figure 1 It is a schematic diagram of the electric field lines between two parallel anode plates and a cathode plate;
[0027] Figure 2 This is a schematic diagram of the overall structure of a specific embodiment of an electroplating baffle capable of establishing a uniform electric field disclosed in this invention.
[0028] Figure 3 This is a partial schematic diagram of the central baffle of a specific embodiment of an electroplating baffle capable of establishing a uniform electric field disclosed in this invention.
[0029] Figure 4 This is a partial schematic diagram of the edge baffle of a specific embodiment of an electroplating baffle capable of establishing a uniform electric field disclosed in this invention.
[0030] Figure label:
[0031] 1. Center baffle; 11. Type I opening;
[0032] 2. Edge baffle; 21. Second type of opening. Detailed Implementation
[0033] The present invention will be further described in detail below with reference to the accompanying drawings.
[0034] To better understand the technical solutions presented in the embodiments of the present invention, the working principle of an existing electroplating process will first be introduced.
[0035] In the PCB electroplating process, a DC electric field is applied between the cathode and anode. Driven by the electric field, metal ions migrate towards the cathode and are reduced and deposited to form a plating layer. Ideally, a uniform electric field is formed between the cathode and anode, resulting in a consistent current density across the cathode surface, thus achieving a plating layer of uniform thickness. However, in actual electroplating tanks, [the following is incomplete and requires further context:] ...referring to... Figure 1 Due to factors such as the edge effect of the electric field, the non-perfect parallelism of the plates, and the complex pattern of the cathode surface, electric field lines are significantly concentrated at the edges and protrusions of the cathode, while they are relatively sparse in the central region or recessed areas. This uneven electric field distribution leads to uneven current density, which in turn causes a series of quality problems: the plating at the edges or protrusions is too thick, rough, or even "burnt"; the plating at the center or recesses is too thin or incomplete; and the plating thickness varies greatly on the patterned lines, affecting the consistency of the line impedance and the reliability of the product.
[0036] Electroplating baffles also exist in existing technologies; however, the implementation process of existing electroplating baffles is quite cumbersome. Typically, an initial electroplating is performed, followed by reverse adjustments based on the electroplating condition of the plated material. Holes are then sealed at relatively concentrated locations, and this process is repeated until completion. However, after design adjustments, further testing and adjustments are required.
[0037] This invention aims to fundamentally intervene in and optimize the original electric field distribution between the anode and cathode through an innovative physical structure design. The core of this invention lies in introducing a specially designed cathode baffle between the anode and cathode. This baffle actively "screens" and "corrects" the passing electric field lines, resulting in a more uniform electric field intensity distribution reaching the cathode surface, thereby obtaining a high-quality coating with a highly consistent thickness.
[0038] Reference Figures 2-4 An electroplating baffle capable of establishing a uniform electric field, disclosed in an embodiment of the present invention, includes a central baffle 1 and an edge baffle 2, wherein the edge baffle 2 is wrapped around the periphery of the central baffle 1.
[0039] The central baffle 1 is provided with an array of first-type openings 11. The design principle of the openings in this area of the array of first-type openings 11 is to maximize the opening ratio, that is, the proportion of the opening area to the total area of the area, while ensuring sufficient mechanical strength, so as to reduce the obstruction of the electric field in the central area and allow most of the electric field lines to pass through smoothly.
[0040] The first type of opening 11 is preferably a regular polygon. In a specific embodiment of the invention, the first type of opening 11 is a regular hexagon, with the entire central baffle 1 forming a honeycomb pattern. This shape is chosen because a regular hexagon is a geometric shape capable of achieving large area coverage and uniform distribution, and its honeycomb arrangement has proven to be efficient and robust in nature and engineering. Using a regular hexagonal aperture array, an almost "transparent" electric field channel can be formed in the central region, allowing electric field lines to pass almost perpendicularly and unobstructed, while the baffle itself maintains optimal structural stability. Figure 3 The diagram shown illustrates this honeycomb structure. It should be understood that the design of the first type of opening 11 is not limited to a regular hexagon. Any shape capable of achieving a similar function—high aperture ratio and uniform conductive field—is acceptable, such as regular polygons like squares or equilateral triangles, and even a circle can be used for the central region.
[0041] The edge baffle 2 is provided with an array of second-type openings 21. In one specific embodiment of the invention, a preferred shape of the second-type openings 21 is circular. Because it is easy to manufacture and has axisymmetric characteristics, it can produce a consistent constraint and correction effect on inclined electric field lines from different directions. Figure 4 A schematic diagram of a circular opening in the edge region is shown.
[0042] The aperture density of the edge baffle 2 is typically lower than that of the central baffle 1 region. By reducing the aperture density, the shielding area of the insulating material against the electric field is increased, thereby physically reducing the total amount of electric field lines reaching the cathode edge. Furthermore, the flux of electric field lines through this region can be further limited by adjusting the aperture size. The aperture can be fixed or designed to be adjustable, for example, by using holes with replaceable plugs to fine-tune the local electric field distribution.
[0043] In some feasible implementations, the distribution of openings in the edge region can be non-uniform. Specifically, but not limited to, the number of openings or the diameter of the openings can be further reduced or decreased in areas where the electric field is most concentrated, such as near the cathode corners; and the opening density or diameter can vary in a gradient from the center to the edge in the transition region.
[0044] The key difference lies in the fact that the second type of opening 21 differs from the first type of opening 11 in shape, size, and / or distribution density. This differentiated design enables a simple physical baffle to intelligently regulate the spatial electric field distribution. For example, a typical preferred embodiment is that the central baffle 1 uses large-diameter regular hexagonal honeycomb holes to achieve high conductivity, while the edge baffle 2 uses smaller-diameter, more sparsely distributed circular holes to achieve strong attenuation and correction.
[0045] It is important to note that this invention does not restrict the shape of the openings. Whether in the central or peripheral region, the shape of the opening can be independently selected from one or more of the following: regular hexagon, circle, ellipse, rectangle, rhombus, or triangle. The key lies in the partitioning and differentiation between regions, rather than adhering to a specific shape. For example, in another feasible embodiment, a circular array of openings can be used in the central region, while a smaller array of square openings can be used in the peripheral region. Furthermore, the peripheral region itself can also employ a combination of two different shapes or sizes of openings to accommodate complex electric field distortion modes.
[0046] In actual installation, the cathode baffle usually needs to be equipped with a simple support frame or suspension to stably fix it in the predetermined position within the electroplating tank and keep it parallel to the anode and cathode. These support structures are conventional technology in this field and will not be described in detail here.
[0047] It should be understood that when a cathode baffle is present, especially if it is thick (e.g., >50mm), the support structure can be rotatable or swingable, allowing the cathode baffle itself to swing / rotate. This can be achieved by adding a reciprocating motor or using a cam structure to drive the cathode baffle to swing back and forth relative to the cathode at an appropriate speed, continuously changing the direction of the electric field lines between the anode and cathode to achieve a more uniform electric field. Simultaneously, the significant swinging of the cathode as a whole can also increase the uniformity of solution mixing, effectively mitigating the risk of reduced solution uniformity when using thicker baffles.
[0048] When using a cathode baffle in an electroplating tank, it should be placed parallel between the anode and cathode, closer to the cathode, to more effectively correct the electric field lines approaching the cathode. The distance between the cathode baffle and the cathode should be set between 20mm and 200mm. The closer the cathode baffle is to the cathode, the stronger its correction of the electric field lines, and the smaller the divergence angle after the correction is complete.
[0049] The area of the cathode baffle needs to be larger than the effective area of the cathode, generally 5% to 20% larger than the effective electroplating area of the cathode, to ensure full coverage of the edge area, while not excessively increasing the size of the equipment and the resistance to electrolyte flow.
[0050] The cathode baffle must be made of insulating materials, such as polyvinyl chloride, polypropylene, polyethylene (PE), polytetrafluoroethylene, polyvinylidene fluoride, or glass fiber reinforced plastic, to ensure that it does not participate in conduction itself and only affects the electric field through its physical structure.
[0051] The thickness of the cathode baffle is a crucial design parameter, typically ranging from 15mm to 200mm. This thickness configuration effectively corrects bent electric field lines near the cathode. The specific thickness needs to be determined comprehensively based on factors such as the electrode spacing of the electroplating tank, the operating voltage, and the degree of electric field distortion to be corrected.
[0052] When an electric field line angled towards a cathode attempts to pass through a hole in an insulating material of a certain thickness, its path is constrained. If the hole is too shallow, the electric field line may only deflect slightly, still reaching the cathode at a large angle, with limited correction. Conversely, if the hole is deep enough, the component of the electric field line perpendicular to the hole wall is attenuated by the strong resistance of the insulating material as it passes through, while the component parallel to the hole axis is preserved and enhanced. This effectively forces the electric field line to align more closely with the hole axis after passing through it.
[0053] The following data were obtained from sampling the coating thickness of the electroplated plate after adding the electroplating baffle disclosed in this invention during the specific experiment:
[0054]
[0055] The following data were obtained from sampling the coating thickness of the electroplated plate without an electroplating baffle during the specific experiment:
[0056]
[0057] The working principle of the device of the present invention is as follows:
[0058] When no cathode baffle is placed, such as Figure 1 To illustrate, the electric field lines between the anode and cathode are approximately parallel in the central part, but diverge and bend outward at the edges, resulting in a much larger number of electric field lines passing through a unit area at the cathode edge than at the center. This is known as the "edge effect".
[0059] After the baffle is inserted, the cathode baffle designed in this invention is placed parallel between the two electrodes. The part of the insulating material without openings completely blocks the direct passage of the electric field lines; the electric field lines can only pass through the opening areas on the baffle.
[0060] In the central region, the dense and regular first-class openings 11 allow most of the electric lines to pass vertically with almost no loss, maintaining the efficient utilization of the electric field in the central region.
[0061] In the edge region, the second type of aperture 21 is similar to a set of "tunable gratings". On the one hand, the reduced aperture area shields some of the excess electric field lines that would originally converge to the edge; on the other hand, the aperture wall with a certain thickness constrains and guides the obliquely incident electric field lines, making their emission direction more vertical.
[0062] Through differentiated design of the opening structure in the central and peripheral regions, the electric field lines originally concentrated at the edges are partially "absorbed" and "straightened," while the electric field lines in the central region are efficiently utilized. Ultimately, the effective electric field line density reaching different positions on the cathode surface is flattened, forming an approximately uniform electric field throughout the entire effective cathode region.
[0063] Under the influence of a uniform electric field, the current density at all points on the cathode surface tends to be consistent, allowing metal ions to be uniformly reduced and deposited, thus obtaining a coating with uniform thickness and dense crystals. At the same time, the stable electric field also helps to stabilize the electrolyte flow field, reduce turbulence and bubbles, and further suppress coating defects.
[0064] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the present invention should be covered within the scope of protection of the present invention.
Claims
1. An electroplating baffle capable of establishing a uniform electric field, characterized in that, include: A cathode baffle is configured to be arranged in parallel between the anode and cathode of the electroplating tank; The area of the cathode baffle is larger than the effective electroplating area of the cathode; The cathode baffle is provided with multiple openings that penetrate its thickness; The cathode baffle has a first type of opening (11) array in its central region and a second type of opening (21) array in its edge region. The first type of opening (11) and the second type of opening (21) are different in shape, size and / or distribution density, so that the cathode baffle can correct the electric field lines from the anode to the cathode and make the electric field distribution reaching the cathode surface uniform.
2. The electroplating baffle capable of establishing a uniform electric field according to claim 1, characterized in that: The shape of the openings in the first type of opening (11) array is a regular polygon.
3. The electroplating baffle capable of establishing a uniform electric field according to claim 2, characterized in that: The regular polygon is a regular hexagon, and the first type of opening (11) array is arranged in a honeycomb pattern.
4. The electroplating baffle capable of establishing a uniform electric field according to claim 1, characterized in that: The openings in the second type of opening (21) array are circular in shape.
5. The electroplating baffle capable of establishing a uniform electric field according to claim 4, characterized in that: The distribution density of the second type of opening (21) is greater than the distribution density of the first type of opening (11) in the central region.
6. The electroplating baffle capable of establishing a uniform electric field according to claim 5, characterized in that: The distribution density of the second type of opening (21) in the edge region decreases in a gradient from the side closer to the center region to the outside further away from the center region.
7. An electroplating baffle capable of establishing a uniform electric field according to any one of claims 1, 4, 5 or 6, characterized in that: The aperture of the second type of opening (21) is adjustable to precisely balance the electric field strength between the cathode edge and the central region.
8. The electroplating baffle capable of establishing a uniform electric field according to claim 1, characterized in that: The area of the cathode baffle is 5% to 20% larger than the effective electroplating area of the cathode, and the distance between the cathode baffle and the cathode is set to 20mm to 200mm.
9. The electroplating baffle capable of establishing a uniform electric field according to claim 1, characterized in that: The cathode baffle has a thickness of 15mm-200mm, and this thickness is configured to provide effective correction and guidance for bent electric lines passing through its openings near the cathode.
10. An electroplating baffle capable of establishing a uniform electric field according to claim 1, characterized in that: The cathode baffle is mounted on the electroplating tank in a swingable or rotatable manner via a supporting member.