Manufacturing method of ultrathin planar transformer coil thick copper PCB

Abstract

The invention belongs to the technical field of ultrathin planar transformers, and particularly relates to a method for manufacturing a thick copper PCB (printed circuit board) of an ultrathin planar transformer coil, which comprises the following steps of: pretreating a base material, selecting an epoxy resin PP (polypropylene) filled copper-clad plate as the base material, performing inner-layer pattern and micro-etching treatment on the surface of the base material, removing an oxide layer and forming a rough surface; the edge of the base material is polished, burrs are removed, and the flatness of the base material is optimized; and steel mesh printing: printing areas except the coil copper layer pattern on the surface of the pretreated base material by adopting a nano steel mesh vacuum printing process. The 2N-layer PCB is divided into two N-layer units for manufacturing, the flatness of the base material is improved in cooperation with ceramic polishing, the alignment error between layers is reduced, and the manufacturing difficulty is lowered; and interlayer bubbles are reduced by a vacuum glue filling process, and the multi-layer thick copper PCB can realize a more ultrathin design on the premise of not influencing the performance, so that the requirement of customers on the ultrathin thick copper of special products is met.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of planar transformers, and particularly relates to a manufacturing method of a super-thin planar transformer coil thick copper PCB. BACKGROUND

[0002] With the increasing demand for high-power-density planar transformers in the fields of new energy vehicles, 5G base stations and ultra-thin power adapters, the demand for multi-layer integration of coil super-thin thick copper PCB (copper layer thickness 80-120 mu m, overall thickness less than or equal to 0.5 mm / single layer) is increasingly urgent. At present, the manufacturing of multi-layer super-thin thick copper PCB mostly adopts a one-time laminating forming process, that is, the base material and the film of 2N layers (N is a positive integer, and N is less than or equal to 6) or more are directly laminated and pressed to realize the multi-layer integration of the coil.

[0003] However, this process has significant bottlenecks: on the one hand, the manufacturing difficulty of 2N layer PCB is much higher than that of two N layer PCB - when 2N layers of base material are laminated, the alignment accuracy between layers is multiplied and becomes more stringent (less than or equal to 0.05 mm), and the traditional PP thick copper filling method is prone to cumulative error due to the doubling of the number of laminated layers, which leads to non-linear increase of the cumulative error, and further causes the coil pattern to be dislocated, and the yield of finished products is less than 70%; at the same time, 2N layer pressing requires higher temperature (greater than or equal to 190 DEG C) and pressure (greater than or equal to 2.5 MPa), which is more than 30% higher than N layer pressing parameters, which not only increases the risk of base material warping and copper layer falling off, but also requires special high-precision pressing equipment, which increases the equipment investment cost by more than 40% compared with N layer PCB manufacturing, and the implementation difficulty is doubled. On the other hand, the cost of 2N layer PCB is significantly higher - after a single pressing failure, the whole board is scrapped, the material loss cost is 3 times that of two N layer PCB, and the cost waste is multiplied; and the process window of subsequent processes such as etching and surface treatment of 2N layer PCB is narrowed by 50% with the number of layers multiplied, which requires additional detection and rework processes, and the labor and time cost is increased by 50% compared with the split manufacturing of two N layer PCB, and the cost burden is doubled.

[0004] In addition, in the existing manufacturing of multi-layer super-thin thick copper PCB, the traditional thick PP filling method cannot meet the interlayer insulation and thinning requirements of 2N layer PCB, and the interlayer bubble rate increases to more than 15% with the increase of the number of layers, which leads to insufficient transformer withstand voltage performance; and if silk screen copper pit filling resin is used, the gap unevenness problem caused by the number of layers being multiplied is aggravated, and there is no effective filling means. Therefore, a manufacturing method of a super-thin planar transformer coil thick copper PCB is proposed to solve the technical problems in the background art. SUMMARY

[0005] The purpose of the present application is to solve the technical problems in the background art by providing a manufacturing method of a super-thin planar transformer coil thick copper PCB.

[0006] Includes the following steps: S1: Pretreatment of inner thick copper substrate. Epoxy resin PP filled copper clad laminate is selected as the substrate. Pattern transfer etching is performed on the surface of the substrate to remove the oxide layer and form a clean and rough surface.

[0007] S2: Steel mesh printing, using nano steel mesh printing technology to print the area on the surface of the pre-treated substrate, except for the area of ​​the filler coil copper pattern, to provide a board plane positioning reference for subsequent multi-layer PP lamination and multi-layer; S3: Disassemble and fabricate single-layer coil boards. Based on the design requirements of planar transformer coils, the 2N-layer coil is split into two groups of N-layer coil units. Fabricate a single-layer coil board for each group of N-layer coil units excluding the copper foil coil unit: S31: Nano steel mesh printing, using a nano steel mesh with adjustable steel sheet to print the substrate, vacuum filling the high temperature dry film with resin, and pressing it onto the surface of the printed substrate. The thickness of the adjustable steel sheet can be adjusted to adapt to different specifications of substrates. S32: Exposure and development. Ultraviolet light is used to expose the substrate after vacuum resin. After exposure, a developing solution is used to develop the substrate, forming a coil pattern and strengthening the curing of the resin material. S33: Thick copper electroplating, the developed substrate is placed in an acidic copper sulfate electroplating solution for electroplating, so that a copper layer of a predetermined thickness is formed in the coil pattern area; S34: The electroplated copper substrate of the vocal cord circuit is immersed in a stripping solution and then polished with ceramic to remove excess resin and roughen the surface to facilitate multilayer board lamination. S35: The inner coil layer and the original copper resin are filled and baked at high temperature to complete the inner thick copper layer filling coil board production. S4: PP selection and lamination preparation: Select PP of appropriate thickness according to the withstand voltage and frequency requirements of the planar transformer; alternately laminate the N-layer single-layer coil board of each group with the selected PP to form a laminated assembly; S5: Vacuum filling and grouping synthesis. Vacuum high temperature PP pressing process is used for the stacked components. The interlayer air is discharged through the vacuum environment to reduce bubbles. Then, vacuum lamination is performed to obtain two N-layer coil units respectively. S6: Unit integration, a selected thickness of PP is laid between two N-layer coil units, and vacuum filling and vacuum lamination processes are used again to achieve the integrated integration of the two N-layer coil units, forming a 2N-layer ultra-thin copper PCB. S7: Outer layer processing and inspection. The outer layer processing is performed on the laminated PCB, followed by inspection of coil impedance, withstand voltage performance and interlayer alignment accuracy. The thick copper PCB of ultra-thin planar transformer coils that meet the requirements is selected.

[0008] As preferred, in step S4, in the voltage resistance frequency range of 1000V to 10000V, the voltage resistance frequency value of the planar transformer is positively correlated with the thickness of the self-insulating layer, that is, when the voltage resistance frequency value of the planar transformer increases towards 10000V, the thickness of the planar transformer increases correspondingly; when the voltage resistance frequency value of the planar transformer decreases towards 1000V, the thickness of the planar transformer decreases correspondingly.

[0009] As preferred, the vacuum glue filling process in steps S5 and S6 is realized by a nano-steel screen printing machine and a vacuum glue filling machine; after the printing operation of the nano-steel screen printing machine is completed, the vacuum glue filling machine starts the glue filling operation, and then the vacuum curing environment is maintained from the completion of the glue filling to the completion of the glue curing before the start of the lamination process, so as to ensure that there is no air bubble between the laminated substrates.

[0010] As preferred, the ceramic polishing in step S1 adopts a grinding wheel polishing mode.

[0011] As preferred, the nano-steel screen printing in step S2 adopts a high-temperature resistant resin ink.

[0012] As preferred, the vacuum lamination process in steps S5 and S6 has a positive correlation between the lamination time and the number of superimposed layers.

[0013] As preferred, in step S33, the thickness of the copper layer after thick copper electroplating is less than 150μm, so as to meet the conductive performance requirements of the planar transformer.

[0014] As preferred, in step S7, laser imaging CCD recognition processing is adopted, and the size precision error of the processed PCB is ≤±0.05mm.

[0015] As preferred, in step S3, if the coil design requirement is other multiple layers, the 2N layers of PCB can be split into multiple coil units according to the principle that the number of layers is ≤6, and then the process of steps S4-S7 is integrated.

[0016] The beneficial effects of the present application are as follows: (1) Difficulty and cost optimization: by splitting the 2N layers of PCB into two N layer units, cooperating with ceramic polishing to improve the flatness of the substrate, reducing the alignment error between layers, and reducing the difficulty of production; the vacuum glue filling process reduces the air bubbles between layers, reduces the failure rate of pressing, reduces material loss, and at the same time, the split production reduces the risk of whole board scrap, greatly reducing the cost.

[0017] (2) Adaptability and performance improvement: according to the voltage resistance frequency, the thickness of PP is selected to adapt the performance requirements of different use scenarios; steel screen printing provides accurate positioning reference to improve the accuracy of coil pattern; vacuum glue filling reduces air bubbles, and PP pressing enhances the insulation and bonding strength between layers, significantly improving the voltage resistance performance and reliability of the PCB.

[0018] (3) Strong process versatility: simplify specific data to expand the protection range, and can be flexibly split into units according to the total number of coil layers, adapt to PCB manufacturing of different layers, and compatible with different voltage and frequency requirements, wider application range. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below, and obviously, the drawings described below are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0020] In the drawings: Figure 1 is the flow chart of the manufacturing method of the present application. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application.

[0022] In order to further illustrate the technical means adopted by the present application and its effects, the technical solutions of the present application will be further described below in combination with the preferred embodiments of the present application, but the present application is not limited in the scope of the embodiments.

[0023] Specific embodiments are given below.

[0024] Please refer to Figure 1 The present application provides a manufacturing method of ultra-thin planar transformer coil thick copper PCB, comprising the following steps: S1: pretreatment of base material, selecting ceramic filled copper clad plate as base material, degreasing and micro-etching the surface of the base material to remove the oxide layer and form a rough surface; ceramic grinding is performed on the edge of the base material to remove burrs and optimize the flatness of the base material; S2: screen printing, using screen printing process to print coil pattern mark on the surface of the pretreated base material, providing positioning reference for subsequent dry film lamination and exposure development; S3: split to make single-layer coil plate, based on the design requirements of planar transformer coil, 2N layers of coil are split into two groups of N layers of coil units, and single-layer coil plates of each group of N layers of coil units are made: S31: nano screen printing, using nano screen printing with adjustable steel sheet to print the base material, filling high-temperature resistant dry film resin in the base material, and pressing the surface of the printed base material, the adjustable steel sheet can be adjusted to adapt to different specifications of the base material; S32: Exposure and development. Ultraviolet light is used to expose the substrate after vacuum resin. After exposure, a developing solution is used to develop the substrate, forming a coil pattern and strengthening the curing of the resin material. S33: Thick copper electroplating, the developed substrate is placed in an acidic copper sulfate electroplating solution for electroplating, so that a copper layer of a predetermined thickness is formed in the coil pattern area; S34: The electroplated copper substrate of the soundboard circuit is immersed in a stripping solution and then polished with ceramic to remove excess resin and roughen the surface to facilitate the lamination of multilayer boards. S35: The inner coil layer and the original copper resin are filled and baked at high temperature to complete the inner thick copper layer filling coil board production. S4: PP selection and lamination preparation: Select PP of appropriate thickness according to the withstand voltage and frequency requirements of the planar transformer; alternately laminate the N-layer single-layer coil board of each group with the selected PP to form a laminated assembly; S5: Vacuum filling and grouping synthesis. Vacuum filling process is used for the stacked components. The interlayer air is discharged through the vacuum environment to reduce air bubbles. Then, vacuum lamination is performed to obtain two N-layer coil units. S6: Unit integration, a selected thickness of PP is laid between two N-layer coil units, and vacuum filling and vacuum lamination processes are used again to achieve the integrated integration of the two N-layer coil units, forming a 2N-layer ultra-thin copper PCB. S7: Shape processing and inspection. The laminated PCB is shaped and then the coil impedance, withstand voltage performance and interlayer alignment accuracy are inspected to screen out the ultra-thin planar transformer coil thick copper PCB that meets the requirements. First, the substrate condition is optimized through substrate pretreatment (including ceramic polishing) to solve the problem of edge burrs in traditional substrates. Then, stencil printing provides a precise positioning benchmark to avoid subsequent pattern offset. Next, a splitting strategy is adopted to produce single-layer coil boards, reducing the difficulty of multi-layer stacking. Then, the PP thickness is selected according to the withstand voltage frequency to achieve scene adaptation. Vacuum filling reduces interlayer bubbles, and PP pressing improves the interlayer bonding strength. Finally, processing and testing ensure the quality of the finished product. The whole process covers four major innovations: "split integration, scene adaptation, precise positioning, and low bubble filling", laying the foundation for subsequent dependent claims.

[0025] In step S4, within the withstand voltage frequency range of 1000V to 10000V, the withstand voltage frequency value of the planar transformer is positively correlated with its own thickness. That is, when the withstand voltage frequency value of the planar transformer increases towards 10000V, the thickness of the planar transformer increases accordingly; when the withstand voltage frequency value of the planar transformer decreases towards 1000V, the thickness of the planar transformer decreases accordingly.

[0026] In the vacuum filling process in steps S5 and S6, the vacuum degree is controlled to be ≤-0.09MPa. The vacuum environment is maintained during the filling process until lamination begins to ensure that there are no air bubbles left between the layers. The key parameters (vacuum degree) and operational requirements of the vacuum filling process are limited. A vacuum degree of ≤-0.09MPa can effectively remove interlayer air and maintain vacuum until lamination begins. This can avoid the secondary introduction of air bubbles during the filling process, directly echoing the innovation of "low-bubble filling", ensuring no air bubbles remain between layers and improving the reliability of PCB insulation.

[0027] In step S1, the ceramic polishing is performed using a grinding wheel. After polishing, the roughness Ra of the substrate edge is ≤1.6μm. Grinding with a grinding wheel can efficiently remove burrs from the edges of the substrate. Roughness control can ensure the sealing of the PP during subsequent lamination and avoid interlayer gaps caused by uneven edges. Combined with the substrate pretreatment process, it solves the problem of scratching the adhesive film on the edges of traditional substrates.

[0028] The stencil printing in step S2 uses high-temperature resistant ink, and the line width error of the printed graphic logo is ≤ ±0.02mm; High-temperature resistant ink can withstand subsequent high-temperature processes such as electroplating and lamination, preventing the markings from falling off. Precise line width error can provide a reliable positioning benchmark for exposure and development, realizing the innovation of "precise positioning" and improving the accuracy of coil pattern production.

[0029] In the vacuum lamination process in steps S5 and S6, the lamination temperature is controlled at 160-288℃, the lamination pressure is controlled at 1.5-2.0MPa, and the lamination time is adjusted according to the number of layers. The lamination time and the number of layers are positively correlated. This parameter range ensures that the PP is fully melted and bonded, while avoiding substrate warping and copper layer detachment caused by high temperature and high pressure. The time can be adjusted as needed to adapt to coil units with different numbers of layers, ensuring the quality of interlayer bonding after disassembly and integration.

[0030] In step S33, the thickness of the copper layer after thick copper electroplating is less than 150μm to meet the conductivity requirements of the planar transformer. This thickness satisfies the high conductivity requirements of planar transformers for coils, ensuring current carrying capacity, while also adapting to the overall thickness requirements of ultra-thin PCBs, avoiding excessive copper layer thickness that could lead to PCB exceeding specifications, thus balancing conductivity and ultra-thin characteristics.

[0031] In step S7, laser cutting is used to process the shape, and the dimensional accuracy error of the processed PCB is ≤ ±0.05mm; Compared to traditional mechanical milling, laser cutting reduces burrs and chipping. Its precise dimensional accuracy ensures the compatibility of PCBs with components such as planar transformer cores, avoiding assembly problems caused by dimensional deviations.

[0032] If the coil design requires a different number of layers in step S3, it can be divided into multiple coil units according to the principle that each layer has ≤6 layers, and then integrated according to the process in steps S4-S7. When the total number of layers is not 2N (such as 3N layers), it can be split according to "each layer ≤ 6 layers". This breaks the limitation of traditional processes that can only adapt to a fixed number of layers, further demonstrating the beneficial effect of "strong process flexibility" and enabling the method to cover the production of ultra-thin and thick copper PCBs with more layer requirements.

[0033] More specifically, step S1: Substrate pretreatment Resin-filled copper clad laminate was selected as the substrate. The substrate was placed in a degreasing tank and soaked in an alkaline degreasing agent (concentration 5wt%) at 50℃ for 10 minutes to remove surface oil. After degreasing, the substrate is transferred to a micro-etching tank and immersed in a micro-etching solution (sulfuric acid + hydrogen peroxide system) at room temperature for 3 minutes. The micro-etching depth is controlled at 0.8 μm to remove the surface oxide layer and form a rough surface. The micro-etched substrate is fixed on a sandblasting machine, and the edges of the substrate are polished with an 800-grit grinding wheel at a speed of 100 mm / s until the surface roughness Ra of the substrate is ≤1.6 μm. Burrs are removed and the flatness is optimized to complete the substrate pretreatment.

[0034] Step S2: Stencil Printing Place the pretreated substrate on the worktable of the stencil printing machine and adjust the printing position so that the printing area matches the subsequent coil pattern area; High-temperature resistant ink (temperature resistance ≥200℃) is used to print coil graphic markings on the substrate surface using a stencil printing machine. The printing pressure is controlled at 0.2MPa and the printing speed is 50mm / s. After printing, the substrate is placed in a drying oven and dried at 120℃ for 5 minutes to cure the ink. The final printed graphic logo line width error is ≤±0.05mm, providing a positioning reference for subsequent processes.

[0035] Step S3: Disassemble and fabricate a single-layer coil board In this embodiment, the 12-layer coil is divided into two groups of 6-layer coil units, and a single-layer coil board is made for each group: S31: Dry film lamination: A high-temperature resistant dry film (40μm thick) is placed on the surface of the printed substrate and put into a vacuum press. The pressing temperature is set to 85℃, the pressure to 0.4MPa and the time to 45s to achieve a tight bond between the dry film and the substrate. S32: Exposure and Development: Place the substrate with the dry film attached into an exposure machine, and expose it with ultraviolet light of wavelength 365nm, based on the graphic markings printed on the stencil, with the exposure energy controlled at 100mJ / cm²; after exposure, place the substrate into a development machine, and develop it with a 1.2wt% sodium carbonate solution at 28°C for 75s to remove the dry film in the unexposed areas, forming a dry film protective layer for the coil pattern; S33: Thick copper electroplating: Place the developed substrate into an electroplating tank, add acidic copper sulfate electroplating solution (containing 210g / L copper sulfate, 55g / L sulfuric acid, 65mg / L chloride ions, and 0.8mL / L brightener), set the electroplating current density to 3A / dm², temperature to 23℃, and time to 75min, so that a copper layer with a thickness of 100μm is formed in the coil pattern area; S34: Dry film stripping and etching: The electroplated substrate is placed in a stripping tank and immersed in an alkaline stripping solution (concentration 8wt%) at 55℃ for 12 minutes to remove the surface dry film protective layer; then the substrate is placed in an etching machine and etched at 42℃ for 6 minutes using an acidic copper chloride etching solution (containing 190g / L copper chloride, 55mL / L hydrochloric acid, 35g / L sodium chloride, and 2.5g / L corrosion inhibitor) to remove the copper layer in the non-coil pattern area; S35: Surface treatment: The etched substrate is placed in an activation tank and immersed in a 0.8wt% sulfuric acid solution at room temperature for 8 seconds to remove the oxide layer on the coil surface; then nickel-gold plating is performed, first nickel plating (temperature 85℃, time 15min, nickel layer thickness 6μm), then gold plating (temperature 90℃, time 2min, gold layer thickness 0.15μm) to complete the fabrication of the single-layer coil board.

[0036] Step S4: PP Selection and Pressing Preparation Each group of 6-layer single-layer coil boards is alternately stacked with selected PP (coil board-PP-coil board...) to form two sets of stacked assemblies, ensuring that the layers in each set are aligned.

[0037] Step S5: Vacuum filling and grouping synthesis Place the two sets of stacked modules into the vacuum filling equipment, turn off the equipment and evacuate the vacuum to ≤-0.09MPa, maintain the vacuum state for 5 minutes, and remove the air between the module layers. Maintain a vacuum environment and inject adhesive (epoxy resin adhesive that matches the PP material) into the interlayer of the module to ensure that the adhesive fills the gaps evenly; The glue-filled components were transferred to a vacuum laminator, and the lamination temperature was set to 170℃, the pressure to 1.8MPa, and the time to 35min for vacuum lamination. After cooling, two 6-layer coil units were obtained.

[0038] Step S6: Unit Integration A selected 0.08mm thick PP layer is laid on the bonding surface of the two 6-layer coil units; Place the stacked units into a vacuum filling device and repeat the vacuum filling operation in step S5 (vacuum degree ≤ -0.09MPa, filling for 5 minutes). The components are transferred to a vacuum laminator and vacuum laminated using the same lamination parameters as in step S5 (170°C, 1.8MPa, 35min) to achieve the integrated integration of two 6-layer coil units, forming a 12-layer ultra-thin copper PCB.

[0039] Step S7: Shape processing and inspection The integrated 12-layer PCB is placed in a laser cutting machine with a laser wavelength of 1064nm, a cutting speed of 80mm / s, and a spot diameter of 0.01mm. The shape is processed according to the design dimensions, and the dimensional accuracy error after processing is ≤±0.02mm. The impedance of the coil is tested using an impedance tester (frequency range 100kHz-1MHz), and the impedance fluctuation is required to be ≤±5%; the withstand voltage performance is tested using a withstand voltage tester (DC1000V, continuous for 60s), and the leakage current is required to be ≤10μA; the interlayer alignment accuracy is tested using an X-ray detector, and the alignment error is required to be ≤±0.01mm. Products that pass all tests are selected as 12-layer ultra-thin copper PCBs suitable for 5G base station planar transformers.

[0040] In the description of this invention, preferred embodiments of the invention have been described in detail above. However, the invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the invention, various simple modifications can be made to the technical solution of the invention, and these simple modifications all fall within the protection scope of the invention.

[0041] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

Claims

1. A method for manufacturing an ultra-thin planar transformer coil thick copper PCB, characterized in that, The method comprises the following steps: S1: inner layer thick copper substrate pretreatment, selecting an epoxy resin PP filling type copper-clad plate as a substrate, performing pattern transfer etching treatment on the surface of the substrate, removing the oxide layer and forming a purified rough surface; S2: steel mesh printing, using a nano steel mesh printing process to print on the surface of the pretreated substrate, in addition to the printed flat coil copper skin pattern, providing a plane positioning reference for subsequent multi-layer PP lamination and multi-layer board; S3: split to make single-layer coil board, based on the design requirements of the planar transformer coil, the 2N layers of coil are split into two groups of N layer coil units, and each group of N layer coil units is made into a single-layer coil board; S4: PP selection and pressing preparation, according to the withstand voltage frequency requirements of the planar transformer, selecting a PP with a corresponding thickness, and alternately stacking each group of N layer single-layer coil boards and the selected PP to form a stacked assembly; S5: vacuum glue filling and group synthesis, using a vacuum high-temperature PP pressing process on the stacked assembly, removing air between the layers to reduce air bubbles, and then performing vacuum lamination to respectively obtain two N layer coil units; S6: unit integration, laying a PP with a selected thickness between the two N layer coil units, and again using the vacuum glue filling and vacuum lamination process to realize the integration of the two N layer coil units, forming a 2N layer ultra-thin thick copper PCB; S7: outer layer processing and detection, outer layer processing is performed on the laminated PCB, and then the coil impedance, withstand voltage performance and interlayer alignment accuracy are detected to screen out the required ultra-thin planar transformer coil thick copper PCB.

2. The method of claim 1, wherein the method further comprises: forming a plurality of vias in the first layer of the PCB; and filling the plurality of vias with a conductive material. In the S3, further comprising: S31: nano steel mesh printing, printing the substrate with an adjustable steel sheet nano steel mesh, filling the high-temperature resistant dry film vacuum resin on the surface of the printed substrate, and pressing it on the surface of the printed substrate, the thickness of the adjustable steel sheet can be adjusted to adapt to different specifications of copper thickness substrate; S32: exposure and development, exposing the substrate after vacuum resin to ultraviolet light, and developing it with a developing solution after exposure to form a coil pattern and strengthen the resin material solidification; S33: thick copper electroplating, placing the developed substrate in an acidic copper sulfate electroplating solution for electroplating, so that the coil pattern area forms a copper layer with a preset thickness; S34: soaking the copper skin substrate after electroplating in a stripping solution and removing excess resin and roughening the surface with ceramic polishing to facilitate multi-layer board pressing; S35: inner layer coil layer and original copper resin flatness high-temperature baking to complete the inner layer thick copper copper layer filling coil board manufacturing.

3. The method for manufacturing an ultra-thin planar transformer coil thick copper PCB according to claim 1, characterized in that: In the step S4, in the withstand voltage frequency range of 1000V to 10000V, the withstand voltage frequency value of the planar transformer is positively correlated with the thickness of the self-insulating layer (PP).

4. The method for manufacturing an ultra-thin planar transformer coil thick copper PCB according to claim 1, characterized in that: The vacuum glue filling process in steps S5 and S6 is realized by a nano steel mesh printer and a vacuum glue filling machine; Wherein, from the completion of the printing work of the nano steel mesh printer to the start of the glue filling work of the vacuum glue filling machine, and then to the completion of the glue filling and until the start of the lamination process, the whole process maintains a vacuum environment to ensure that there is no air bubble residue between the layers of the substrate to be laminated.

5. The method of claim 1, wherein the method further comprises: forming a plurality of vias in the first layer of the PCB; and filling the plurality of vias with a conductive material. The ceramic polishing in step S1 adopts a grinding wheel polishing method.

6. The method of claim 1, wherein the method further comprises: forming a plurality of vias in the first layer of the PCB; and filling the plurality of vias with a conductive material. The nano steel mesh printing in step S2 uses a high-temperature resistant resin material ink.

7. The method of claim 1, wherein the thickness of the copper is 3 oz. or more. The vacuum laminating process in steps S5 and S6 has a positive correlation between laminating time and the number of laminated layers.

8. The method of claim 1, wherein the thickness of the copper is 3 oz. or more. In step S33, the thickness of the copper layer after thick copper plating is less than 150 μm to meet the conductive performance requirements of the planar transformer.

9. The method for manufacturing an ultra-thin planar transformer coil thick copper PCB according to claim 1, characterized in that: In step S7, laser imaging CCD recognition processing is used, and the size accuracy error of the processed PCB is ≤±0.05 mm.

10. The method of making according to any one of claims 1-9, wherein: In step S3, if the coil design requirement is other multiple layers, the coil unit can be divided into multiple coil units according to the principle of ≤6 layers per layer, and then integrated according to the processes of steps S4-S7.

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