A deep etching device for automotive thick copper PCB boards with gradient current density

Abstract

The present invention relates to the technical field of circuit board etching, and discloses a device for deep etching thick copper PCBs for automobiles with a gradient current density. The device comprises an etching tank, wherein an electrode system is symmetrically arranged on the inner wall of the etching tank. The electrode system comprises a movable member arranged on the inner wall of the etching tank, an isolating member is arranged on the other end of the movable member, and an electrode body is arranged on the other end of the isolating member. The movable member comprises a slide rail fixedly arranged on the inner wall of the etching tank, and a fixed block is slidably connected to the inner wall of the slide rail. The invention is provided with an electrode body with a variable pitch design, which shortens the spacing between the electrode bodies in thick copper or slow-etching areas, enhances the local electric field strength, and accelerates the etching rate; increases the spacing between the electrode bodies in areas prone to over-etching, reduces the electric field strength, and slows down the etching rate, thereby balancing the etching efficiency of different areas, significantly improving etching uniformity, reducing the risk of side etching and copper layer residue, and meeting the high-precision manufacturing requirements of automotive thick copper PCBs.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board etching, and in particular to a deep etching device for an automobile thick copper PCB board with a gradient current density. Background Art

[0002] The development of automotive thick copper PCBs is primarily driven by the high-power electronic systems of new energy vehicles, such as battery management systems, motor controllers, and onboard charging stations, which require currents exceeding 200A. Thick copper PCBs meet these high-current and high-heat dissipation requirements through their low-resistance design and efficient heat dissipation, adapting to the 800V high-voltage platform and harsh environments of electric vehicles. In actual production, the etching process first uses an acidic etching tank to rough-etch the majority of the copper layer. Tinning is then applied to the sidewalls of the circuits through a tinning line for protection. Finally, an alkaline etching SES line refines the remaining copper layer, combining a high-pressure spray system and oscillating spray arms to enhance the permeability of the chemical solution.

[0003] The copper layer thickness of automotive thick copper PCB boards is usually relatively high. Traditional fixed-pitch electrodes and uniform current density are prone to edge effects, that is, the edges of the board are over-etched due to current concentration, while the center area is not thoroughly etched due to insufficient current distribution, resulting in "edge depression" or "center residue"; thick copper etching requires a high aspect ratio, and the vertical etching rate and lateral etching rate are difficult to balance in traditional processes, which can easily lead to excessive lateral etching or slow etching speed; thick copper layer etching is time-consuming, and under traditional uniform current density, the overall current intensity is limited by the process's need to avoid edge overetching, resulting in a forced reduction in the etching rate in the center area; micro-etching treatment is required after thick copper etching to roughen the copper surface, but in traditional processes, the uniformity of micro-etching is easily affected by etching residue or surface condition. Summary of the Invention

[0004] Technical problems solved

[0005] To address the above-mentioned shortcomings of the existing technology, the present invention provides a gradient current density deep etching device for automotive thick copper PCBs. This device can effectively solve the problems of the existing technology caused by traditional fixed-spacing electrodes and uniform current density, such as insufficient uniformity, difficulty in etching high aspect ratios, low efficiency, and difficulty in micro-etching control during etching of automotive thick copper PCBs.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] The present invention provides a device for deep etching of thick copper PCB boards for automobiles with a gradient current density, comprising:

[0008] An etching groove, wherein an electrode system is symmetrically arranged on the inner wall of the etching groove, the electrode system includes a movable member arranged on the inner wall of the etching groove, an isolating member is arranged on the other end of the movable member, and an electrode body is arranged on the other end of the isolating member, the movable member includes a slide rail fixedly arranged on the inner wall of the etching groove, a fixed block is slidably connected to the inner wall of the slide rail, the isolating member includes a protective layer connected to the other end of the fixed block, the other end of the protective layer is fixedly connected to a baffle, in an initial state, the other end of the protective layer in the middle position is fixedly connected to the baffle, and the other end of the baffle is embedded in the adjacent protective layer;

[0009] Wherein, a tooth plate is provided in the middle of the baffle. When the distance between the protective layers increases, the protective layers drive the tooth plate to move, and the movement of the tooth plate applies a force to the electrode body.

[0010] Furthermore, the movable part also includes a driver fixed in the middle of the slide rail, the output end of the driver is transmission-connected to a telescopic rod, and both ends of the telescopic rod are fixedly connected to a fixed block.

[0011] Furthermore, the other end of the fixed block is fixedly connected to a fixed rod, the other end of the fixed rod is fixedly connected to a tooth plate, the side of the tooth plate is meshed with a gear, a vertical rod is provided through the middle of the gear, the vertical rod is rotatably connected to the top of the inner wall of the electrode body, and both ends of the vertical rod are fixedly connected to an eccentric wheel.

[0012] Furthermore, in the initial state, the side of the eccentric wheel is in contact with the outer wall of the electrode body, and the contact position is at the minimum diameter of the eccentric wheel.

[0013] Furthermore, the inner wall of the electrode body adopts an arc design, and both ends of the electrode body adopt an arc design.

[0014] Furthermore, the outer wall of the electrode body is symmetrically provided with grooves for facilitating the flow of etching liquid.

[0015] Furthermore, in the initial state, the distance between the electrode bodies is the smallest, and the tooth plates and the fixing rods are both embedded in the side protection layer.

[0016] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0017] The present invention is provided with an electrode body with a variable pitch design, which shortens the electrode body spacing in thick copper or slow-etching areas, enhances the local electric field strength, and accelerates the etching rate; increases the electrode body spacing in areas prone to over-etching, reduces the electric field strength, and slows down the etching rate, thereby balancing the etching efficiency in different areas, significantly improving etching uniformity, reducing the risk of side etching and copper layer residue, and meeting the high-precision manufacturing requirements of automotive thick copper PCBs.

[0018] The electrode body of the present invention adopts an arc-shaped design. The arc-shaped contour can optimize the electric field distribution, reduce the edge effect, make the current density more uniform, and improve the etching consistency; the concave design of the inner wall can guide the convergence of electric lines, enhance the local electric field strength, meet the needs of rapid etching of thick copper, and at the same time promote the orderly flow of etching liquid and reduce turbulent interference; the arc shape of the upper and lower ends can reduce fluid resistance, reduce the impact and splash of etching liquid when the electrode body moves, and help to discharge bubbles, avoiding the adverse effects of air film on etching; the combination of the three can also enhance the structural strength of the electrode body, reduce stress concentration, reduce mechanical wear, and extend the service life of the electrode body, providing efficient and stable support for the PCB etching process.

[0019] When the spacing between the electrode bodies of the present invention increases, the baffle moves synchronously to fill the gap, which can suppress the sudden change in flow velocity and turbulence abnormalities caused by the spacing change, and improve the flow uniformity of the etching liquid; enhance the rigidity of the electrode body and ensure the positioning accuracy of dynamic adjustment; and be compatible with the dual requirements of thick copper etching using small spacing and high current and complex plate types using large spacing + partition control, reducing equipment switching costs.

[0020] During the linear movement of the baffle of the present invention along the slide rail, the eccentric wheel arranged on the inner wall converts the linear motion of the baffle into its own rotational motion around the axis by means of gear transmission; as the eccentric wheel continues to rotate, its geometric center and the rotation center are offset, generating a periodically changing radial force, which is transmitted to the electrode body attached to the other side through the flexible layer arranged on the outer wall, driving the electrode body to generate forced vibration with a specific frequency and amplitude, thereby achieving disturbance of the boundary layer on the surface of the electrode body, bubble removal and improvement of mass transfer efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0022] Figure 1 Schematic diagram of the overall structure of an embodiment of the present invention;

[0023] Figure 2 Schematic diagram of the electrode system in a variable distance state according to an embodiment of the present invention;

[0024] Figure 3 Schematic diagram of the split structure of the electrode system according to an embodiment of the present invention;

[0025] Figure 4 A schematic diagram of the structure of movable parts according to an embodiment of the present invention;

[0026] Figure 5 This is a schematic diagram of the baffle connection structure according to an embodiment of the present invention;

[0027] Figure 6 Schematic diagram of the structure of an isolation element according to an embodiment of the present invention;

[0028] Figure 7 Schematic diagram of the electrode body structure of an embodiment of the present invention.

[0029] The numbers in the figure represent: 1. Etching groove; 2. Electrode system; 21. Moving part; 211. Slide rail; 212. Driver; 213. Telescopic rod; 214. Fixed block; 22. Isolator; 221. Protective layer; 222. Baffle; 223. Tooth plate; 224. Fixed rod; 225. Gear; 226. Vertical pole; 227. Eccentric wheel; 23. Electrode body; 231. Groove. DETAILED DESCRIPTION

[0030] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0031] The present invention will be further described below with reference to the embodiments.

[0032] Example:

[0033] See also Figure 1-Figure 7 The present invention provides a technical solution for a deep etching device for automotive thick copper PCB boards with a gradient current density:

[0034] refer to Figure 1 The device includes an etching tank 1, and the inner wall of the etching tank 1 is provided with an electrode system 2 for applying an electric field to drive ion migration and compensate for regional etching differences.

[0035] In the prior art, the electrode bodies 23 of the etching tank 1 are designed with a fixed spacing. Because the electrode bodies 23 are fixed to generate a uniform density electric field, when etching thick copper PCBs, uneven etching is prone to occur due to the microscopic unevenness, uneven thickness and "edge effect" of the electric field distribution on the thick copper surface. The etching speed at the edges or protrusions of the board surface is too fast due to the concentrated electric field, resulting in severe side etching and narrowed line width. The central area or recessed area etches slowly due to the weak electric field. The exchange of chemical solution in the central area is hindered, and the ion diffusion rate is lower than that at the edge, resulting in copper layer residue or large thickness deviation. The uniform electric field cannot compensate for this difference, resulting in a high etching rate difference, deteriorated line width uniformity, and limited aspect ratio. The present invention adopts a new type of electrode body 23 system. By shortening the spacing of the electrode bodies 23 in thick copper or slow-etching areas, the local electric field strength is enhanced to accelerate the etching rate; the spacing of the electrode bodies 23 in areas prone to over-etching is increased to reduce the electric field strength and slow the etching speed, thereby balancing the etching efficiency of different areas, significantly improving etching uniformity, reducing the risk of side etching and copper layer residue, and meeting the high-precision manufacturing requirements of automotive thick copper PCBs.

[0036] refer to Figure 2 、 Figure 3 and Figure 4 The electrode system 2 includes a movable part 21 arranged on the inner wall of the etching groove 1, an isolation part 22 is arranged at the other end of the movable part 21, and an electrode body 23 is arranged at the other end of the isolation part 22. The movable part 21 includes a slide rail 211 fixedly arranged on the inner wall of the etching groove 1, and a fixed block 214 is slidably connected to the inner wall of the slide rail 211. The movable part 21 also includes a driver 212 fixed to the middle of the slide rail 211, and the output end of the driver 212 is transmission-connected to a telescopic rod 213, and both ends of the telescopic rod 213 are fixedly connected to the fixed block 214.

[0037] The driver 212 extends and retracts through the telescopic rod 213, driving the symmetrical fixed block 214 to move. When facing thick copper or fast etching, the spacing is reduced, and the pulse current is used to suppress side reactions; when facing fine lines, the spacing is increased, and the current density lower limit is maintained in combination with high-concentration electrolyte; when facing complex board types, dynamic spacing + partition control is used to match the etching needs of different areas in real time.

[0038] As the spacing between the electrode bodies 23 decreases, the current density increases, and as the spacing between the electrode bodies 23 increases, the current density decreases. The electrode bodies 23 are driven to move by a servo motor, and the spacing is adjusted in real time in combination with online detection such as laser ranging or current sensors to ensure the stability of the current density of circuit boards of different sizes.

[0039] refer to Figure 2 and Figure 7The outer wall of the electrode body 23 is symmetrically provided with grooves 231 to facilitate the flow of etching liquid. In the initial state, the spacing between the electrode bodies 23 is minimal, and the tooth plate 223 and the fixing rod 224 are both embedded in the side protection layer 221. Compared with the rectangular electrode body 23 in the prior art, the electrode body 23 of the present invention adopts an arc-shaped design, the inner wall of the electrode body 23 adopts an inward concave design, and the upper and lower ends of the electrode body 23 are set as arcs.

[0040] The sharp corners of the rectangular electrode body 23 can easily lead to electric field concentration, exacerbating overetching at the edges or corners of the board during movement, especially when etching thick copper, which can easily cause "edge dents." The circular arc profile of the curved electrode body 23, on the other hand, disperses the electric field intensity, preventing sudden changes in the electric field at sharp corners. As the curved electrode body 23 moves, the distance between its curved surface and the PCB surface changes more gradually, effectively reducing the peak current density at the edge, minimizing etching deviations caused by uneven electric fields, and improving etching uniformity across the board.

[0041] The straight edges or right-angle structures of the rectangular electrode body 23 are difficult to accurately match the contours of the graphics through the moving trajectory when facing arc-shaped, circular pads or special-shaped lines on the PCB board. Etching deviations may occur due to insufficient or excessive coverage of the local electric field, such as incomplete etching of the pad edge or excessive side etching at the corners of the lines; while the curved contours and movement trajectories of the arc-shaped electrode body 23 can better fit the edges of complex graphics such as arcs, bevels, etc.; when the electrode body 23 moves along the pad, the arc-shaped surface can maintain an equal distance or gradual spacing from the edge of the pad, making the electric field distribution around the pad more uniform, avoiding local insufficient etching or over-etching caused by the "right-angle alignment" of the traditional rectangular electrode body 23, and is particularly suitable for the precision etching of high-density special-shaped lines in automotive PCBs.

[0042] When the rectangular electrode body 23 moves, its right-angled edges can easily disrupt the flow of the etching solution, creating localized turbulence or eddies. This can lead to uneven ion distribution in the etching solution, such as ion accumulation or oxidant depletion, and affect the stability of the etching rate. The smooth curved surface of the arc-shaped electrode body 23 reduces fluid resistance, gently stirring the etching solution during movement and reducing turbulence. This stable flow helps evenly diffuse ions in the etching solution across the board surface, maintaining a consistent etching reaction rate across all areas. This is particularly suitable for thick copper etching applications, where dynamic equilibrium of the etching solution is critical.

[0043] The sharp edges of the rectangular electrode body 23 are prone to friction with the inner wall of the etching groove 1 or the PCB board surface during long-term movement, causing the surface of the electrode body 23 to wear or scratch the board surface, affecting the etching accuracy and even causing equipment failure; while the arc-shaped electrode body 23 has no sharp edges and corners, and the contact with the surrounding components is smoother during movement, which can significantly reduce the risk of mechanical wear and extend the service life of the electrode body 23. At the same time, it reduces the frequency of downtime maintenance due to mechanical failure and improves production efficiency.

[0044] By optimizing its geometry and adapting its kinematic characteristics, the arc-shaped electrode body 23 significantly outperforms its rectangular counterpart in terms of electric field uniformity, compatibility with complex patterns, etching solution stability, and equipment durability. It is particularly well-suited for the high-precision, high-reliability etching requirements of thick copper automotive PCBs, effectively improving etching quality and reducing process risks.

[0045] In the present invention, the surface of the electrode body 23 is plated to improve corrosion resistance and reduce residue adhesion, but residue deposition still exists on its surface, and the electrode body 23 needs to be electrolytically cleaned or chemically cleaned regularly. During the cleaning process, residues are removed from the corners of the arc-shaped electrode body 23 and the fixed shaft;

[0046] The arc-shaped profile lacks sharp corners, reducing the likelihood of residues such as copper particles and polymers being trapped due to mechanical collisions. Especially when the electrode body 23 moves, the smooth curved surface allows fluid flushing to more easily remove attached impurities. The arc-shaped structure reduces turbulence in the etching solution as it flows across the surface of the electrode body 23, resulting in a more uniform flow rate distribution. This kinetic energy can then be used to remove small particles, inhibiting the deposition of residues.

[0047] When the distance between the electrode bodies 23 changes periodically, such as approaching and moving away from the PCB surface, the relative movement between the surface of the electrode bodies 23 and the etching liquid intensifies, generating a fluid disturbance similar to a "piston effect", which can peel off the adsorbed light residue.

[0048] During the pitch change process, the electric field strength is dynamically adjusted, so that the charged residue adsorbed on the surface of the electrode body 23 falls off due to the change in the electric field force and is discharged with the liquid flow.

[0049] The distance between the electrode bodies 23 adjusts the current density. During the etching process, the variable-pitch electrode body 23 system can adjust the current density in real time based on the distance between the electrode body 23 and the workpiece. When the electrode body 23 is close to the workpiece, the current density is appropriately reduced to avoid excessive current that may cause excessive or uneven etching. When the electrode body 23 is far from the workpiece, the current density is increased to ensure the etching effect.

[0050] refer to Figure 5 and Figure 6The isolating member 22 includes a protective layer 221 connected to the other end of the fixed block 214, and the other end of the protective layer 221 is fixedly connected to a baffle 222. In the initial state, the other end of the protective layer 221 in the middle position is fixedly connected to the baffle 222, and the other end of the baffle 222 is embedded in the adjacent protective layer 221. A tooth plate 223 is provided in the middle of the baffle 222. When the distance between the protective layers 221 increases, the protective layer 221 drives the tooth plate 223 to move, and the tooth plate 223 moves to exert force on the electrode body 23. The other end of the fixed block 214 is fixedly connected to a fixed rod 224, and the other end of the fixed rod 224 is fixedly connected to the tooth plate 223. The side of the tooth plate 223 is meshed with a gear 225. A vertical rod 226 is provided through the middle of the gear 225. The vertical rod 226 is rotatably connected to the top of the inner wall of the electrode body 23. The two ends of the vertical rod 226 are fixedly connected to the eccentric wheel 227. In the initial state, the side of the eccentric wheel 227 is in contact with the outer wall of the electrode body 23, and the contact position is the minimum diameter of the eccentric wheel 227.

[0051] When the distance between the electrode bodies 23 increases, the baffle 222 moves synchronously to fill the gap, thereby avoiding a sudden increase in the fluid cross-sectional area caused by a sudden change in the distance, and preventing a sudden drop in the flow rate of the etching solution or the generation of eddy currents.

[0052] The baffle 222 is connected to the electrode body 23 to form an approximately "continuous wall", which reduces the fluid separation phenomenon at the edge of the electrode body 23. Especially when controlling complex plate partitions, it can avoid flow velocity fluctuations at the junction of different spacing areas and improve etching uniformity.

[0053] The baffle 222 rigidly connects the separated electrode bodies 23 to form a "frame structure" to offset the lateral force when the mover is driven, avoiding the cantilever beam effect caused by the increase in the spacing between the electrode bodies 23, and is particularly suitable for high-frequency dynamic adjustment scenarios.

[0054] The baffle 222 is slidably connected to the inner wall of the slide rail 211, and the mechanical limit is used to ensure the precise coupling between the distance between the electrode bodies 23 and the position of the baffle 222, thereby avoiding the distance control error caused by mechanical clearance.

[0055] The inner side of the baffle 222 is designed as an inclined guide surface to guide the etching liquid to flow in a preset direction. Cooperating with the arc end of the arc-shaped electrode body 23, a spiral upward flow field is formed to accelerate the floating and discharge of bubbles.

[0056] In areas where the electrode bodies 23 are spaced relatively large, the baffle 222 can fill the irregular gaps between the electrode bodies 23 to prevent the etching liquid from being retained in the "corners", which is particularly suitable for deep cavity etching requirements when processing multi-layer boards or blind hole structures.

[0057] The baffle 222 is made of conductive material and is grounded. It acts as a "virtual electrode body 23" to participate in the regulation of electric field distribution. By changing the relative position of the baffle 222 and the electrode body 23, the electric field strength of the effective etching area is dynamically adjusted to achieve flexible regulation of current density.

[0058] This design, which uses baffles 222 to bridge the gap between the electrode bodies 23, is essentially an integrated solution for fluid control, mechanical stability, and electric field regulation. This design suppresses sudden changes in flow velocity and turbulence caused by spacing variations, improving the uniformity of the etching solution flow. It also enhances the rigidity of the electrode bodies 23, ensuring dynamic positioning accuracy. It also accommodates the dual requirements of thick copper etching, fine pitch, high current, and complex plate types, large pitch and partition control, reducing equipment switching costs.

[0059] During the linear movement of the baffle 222 along the slide rail 211, the eccentric wheel 227 arranged on the inner wall converts the linear motion of the baffle 222 into its own rotational motion around the axis by means of transmission devices such as the gear 225 and the synchronous belt; as the eccentric wheel 227 continues to rotate, its geometric center and the rotation center are offset, generating a periodically changing radial force, which is transmitted to the electrode body 23 attached to the other side through the flexible connector, driving the electrode body 23 to generate forced vibration with a specific frequency and amplitude, thereby achieving disturbance of the boundary layer on the surface of the electrode body 23, bubble removal and improvement of mass transfer efficiency.

[0060] During the etching process, a stagnant boundary layer forms on the surface of the electrode body 23, hindering the exchange of substances between the active ions in the etching solution and the surface of the electrode body 23. The vibration of the electrode body 23 generated by this structure can effectively destroy the boundary layer, reducing its thickness. This greatly accelerates the diffusion rate of active ions in the etching solution to the copper surface, significantly improving the mass transfer coefficient. The improved mass transfer efficiency allows the etching reaction to proceed more quickly and fully, especially when etching thick copper, which can significantly shorten the etching time and improve production efficiency.

[0061] Bubbles generated during the etching process tend to adhere to the surface of the electrode body 23, forming an air film that hinders the etching reaction and leads to localized insufficient or uneven etching. The inertial force and acoustic streaming effect generated by the vibration of the electrode body 23 effectively remove tiny bubbles adhering to the surface of the electrode body 23, while also causing small bubbles to coalesce and form larger bubbles, accelerating their upward movement and discharge. This significantly reduces the gas content in the etching solution, mitigates the negative impact of bubbles on etching quality, and improves etching uniformity and surface quality.

[0062] During the bonding process of the electrode body 23, local stress concentration is likely to occur due to factors such as processing errors, which may damage the coating of the electrode body 23 and affect the service life and performance of the electrode body 23. The micro-displacement and force generated by the vibration of the eccentric wheel 227 can offset some of the local stress and make the contact pressure more evenly distributed. This not only reduces the risk of peeling of the coating of the electrode body 23, but also alleviates the problem of uneven thermal expansion of the electrode body 23 caused by Joule heat during the etching process, improves the accuracy of maintaining the spacing between the electrode bodies 23, extends the service life of the electrode body 23, and ensures the stability and reliability of the etching process.

[0063] Using gear 225 and toothed plate 223, the linear motion of baffle 222 is cleverly converted into the rotational motion of eccentric wheel 227. This motion conversion method is simple in structure, ingenious in design, and easy to implement and maintain. By adjusting parameters such as the eccentricity and rotational speed of eccentric wheel 227, the frequency and amplitude of the vibration of electrode body 23 can be precisely controlled to adapt to different etching process requirements, providing strong flexibility and adjustability.

[0064] This structure can work in conjunction with other etching process parameters such as the spacing between the electrode bodies 23, the flow rate and temperature of the etching solution to further optimize the etching process and improve the overall performance and production efficiency of the equipment.

[0065] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A deep etching device for automotive thick copper PCB boards with a gradient current density, characterized in that: include: An etching groove (1), wherein an electrode system (2) is symmetrically arranged on the inner wall of the etching groove (1), the electrode system (2) comprises a movable part (21) arranged on the inner wall of the etching groove (1), an isolating part (22) is arranged at the other end of the movable part (21), an electrode body (23) is arranged at the other end of the isolating part (22), the movable part (21) comprises a slide rail (211) fixedly arranged on the inner wall of the etching groove (1), a fixed block (214) is slidably connected to the inner wall of the slide rail (211), the isolating part (22) comprises a protective layer (221) connected to the other end of the fixed block (214), the other end of the protective layer (221) is fixedly connected to a baffle (222), in an initial state, the other end of the protective layer (221) at the middle position is fixedly connected to the baffle (222), and the other end of the baffle (222) is embedded in the adjacent protective layer (221); A tooth plate (223) is provided in the middle of the baffle (222); when the spacing between the protective layers (221) increases, the protective layers (221) drive the tooth plate (223) to move, and the movement of the tooth plate (223) exerts a force on the electrode body (23).

2. The deep etching device for thick copper PCB with gradient current density according to claim 1, characterized in that: The movable part (21) further includes a driver (212) fixed to the middle of the slide rail (211), the output end of the driver (212) is transmission-connected to a telescopic rod (213), and both ends of the telescopic rod (213) are fixedly connected to a fixed block (214).

3. The deep etching device for thick copper PCB with gradient current density according to claim 2, characterized in that: The other end of the fixed block (214) is fixedly connected to a fixed rod (224), the other end of the fixed rod (224) is fixedly connected to a toothed plate (223), the side of the toothed plate (223) is meshedly connected to a gear (225), a vertical rod (226) is provided through the middle of the gear (225), the vertical rod (226) is rotatably connected to the top end of the inner wall of the electrode body (23), and the two ends of the vertical rod (226) are fixedly connected to eccentric wheels (227).

4. The device for deep etching thick copper PCB with gradient current density according to claim 3, characterized in that: In the initial state, the side of the eccentric wheel (227) is in contact with the outer wall of the electrode body (23), and the contact position is at the minimum diameter of the eccentric wheel (227).

5. The deep etching device for thick copper PCB with gradient current density according to claim 4, characterized in that: The inner wall of the electrode body (23) is designed in an arc shape, and both ends of the electrode body (23) are designed in an arc shape.

6. The deep etching device for thick copper PCB with gradient current density according to claim 5, characterized in that: The outer wall of the electrode body (23) is symmetrically provided with grooves (231) for facilitating the flow of etching liquid.

7. The deep etching device for thick copper PCB with gradient current density according to claim 5, characterized in that: In the initial state, the distance between the electrode bodies (23) is the smallest, and the tooth plates (223) and the fixing rods (224) are both embedded in the side protection layer (221).

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