Thick copper printed circuit board processing method and thick copper printed circuit board
By using two symmetric etching methods during the processing of thick copper printed circuit boards, the problems of infinity of etching and large differences in line width in the prior art are solved, and the processing yield and accuracy are improved.
Patent Information
- Application Number
- CN202510446287.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-09
- Publication Date
- 2025-06-27
AI Technical Summary
In the existing thick copper printed circuit board processing methods, etching with copper thickness exceeding 5OZ is affected by the etching factor, resulting in large differences in widths between the line surface and the line base, and it is easy to cause poor etching, resulting in low processing yield.
The method of two symmetric etching is adopted, the first etching does not penetrate the copper layer of the thick copper core plate is etched, and the second etching penetrates the copper layer to form a symmetrical etching line, reducing the depth of a single etching and reducing the influence of the etching factor.
The accuracy of line width and line spacing is significantly improved, short circuit problems caused by burrs and incomplete etching are avoided, and the processing yield of thick copper printed circuit boards is improved.
Smart Images
Figure CN120224577A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of printed circuit board manufacturing, and particularly to a processing method for a thick copper printed circuit board and a thick copper printed circuit board. Background Art
[0002] In recent years, power products have been developing towards high frequency, high power density, high power factor, high efficiency, high reliability, high heat dissipation, and high intelligence. A thick copper printed circuit board is a special type of printed circuit board, which is characterized by using a relatively thick copper foil layer and has excellent heat dissipation performance. It is mainly used in application scenarios with high power and high heat dissipation requirements such as power boards and energy boards.
[0003] The existing processing method for thick copper printed circuit boards is to use a thick copper core board as the core board, cover photosensitive dry film on both sides, and complete the production of double-sided circuits at one time through exposure, development, and etching. The etching depth directly penetrates the thick copper layer. After brownification treatment of the double-sided circuits after etching, multiple double-sided thick copper core boards are stacked through a connecting PP (Prepreg) containing glass fiber cloth, and copper foil is covered on the outer layer, and then pressed and synthesized into a multi-layer board under high temperature and high pressure.
[0004] However, in the existing processing method for thick copper printed circuit boards, since the etching ability of the conventional method for etching circuits is 5OZ copper thickness, the etching of copper thickness exceeding 5OZ is affected by the etching factor, resulting in a large difference in the width between the line surface and the line bottom, and it is easy to produce the defect of incomplete etching. The above factors lead to a low processing yield of thick copper printed circuit boards. Summary of the Invention
[0005] The present application provides a processing method for a thick copper printed circuit board and a thick copper printed circuit board, so as to solve the problem that in the existing processing method for thick copper printed circuit boards, the etching of copper thickness exceeding 5OZ is affected by the etching factor, resulting in a large difference in the width between the line surface and the line bottom, and it is easy to produce the defect of incomplete etching, resulting in a low processing yield of thick copper printed circuit boards.
[0006] In a first aspect, the present application provides a processing method for a thick copper printed circuit board, the method comprising:
[0007] Performing an anti-etching treatment on a first surface of a thick copper core board to form a first anti-etching protection layer;
[0008] Performing a first single-sided treatment on a second surface of the thick copper core board, the second surface being the opposite surface of the first surface, the single-sided treatment comprising: etching the surface of the thick copper core board according to a circuit pattern to form an etched circuit; in the first single-sided treatment, the etching does not penetrate the copper layer of the thick copper core board;
[0009] Removing the first anti-etching protection layer, performing the anti-etching treatment on the second surface to form a second anti-etching protection layer;
[0010] Perform the second single-sided treatment on the first surface of the thick copper core board. The etching lines formed by the first single-sided treatment and the second single-sided treatment are symmetric on both sides of the thick copper core board. In the second single-sided treatment, etch through the copper layer of the thick copper core board;
[0011] Remove the second anti-etching protection layer to form a circuit core board.
[0012] In a possible implementation, after etching the surface of the thick copper core board according to the circuit pattern to form an etching line, the single-sided treatment further includes:
[0013] Press a flowable insulating protector on the etched surface of the thick copper core board that has not undergone the anti-etching treatment, so that the flowable insulating protector fills into the etching line and covers the etched surface to form an insulating protection layer. The etched surface is the surface of the thick copper core board after etching.
[0014] In a possible implementation, the pressing a flowable insulating protector on the etched surface of the thick copper core board that has not undergone the anti-etching treatment, so that the flowable insulating protector fills into the etching line and covers the etched surface to form an insulating protection layer. The etched surface is the surface of the thick copper core board after etching includes:
[0015] Coat pure glue on the etched surface;
[0016] Perform a pressing treatment on the pure glue so that the pure glue fills into the etching line and covers the etched surface;
[0017] Perform a thermal curing treatment on the pure glue to form the insulating protection layer.
[0018] In a possible implementation, the pressing a flowable insulating protector on the etched surface of the thick copper core board that has not undergone the anti-etching treatment, so that the flowable insulating protector fills into the etching line and covers the etched surface to form an insulating protection layer. The etched surface is the surface of the thick copper core board after etching:
[0019] Spray benzoxazine resin onto the etched surface;
[0020] Perform a pressing treatment on the benzoxazine resin so that the benzoxazine resin fills into the etching line and covers the etched surface;
[0021] Perform a curing treatment on the benzoxazine resin to form the insulating protection layer.
[0022] In a possible implementation, the performing the anti-etching treatment at the second surface to form a second anti-etching protection layer includes:
[0023] At the second surface, an anti-etching protective film is laminated on the surface of the insulating protective layer as the second anti-etching protective layer.
[0024] In a possible implementation, after removing the second anti-etching protective layer to form a circuit core board, the method further includes:
[0025] Alternately stacking a plurality of the circuit core boards and a plurality of insulating dielectric layers, and placing the insulating dielectric layer between the insulating protective layers of two adjacent circuit core boards;
[0026] Pressing the alternately stacked plurality of circuit core boards and a plurality of insulating dielectric layers to form a multi-layer circuit core board.
[0027] In a possible implementation, the insulating dielectric layer is a prepreg made of epoxy resin.
[0028] In a possible implementation, the insulating dielectric layer is a prepreg made of polytetrafluoroethylene.
[0029] In a possible implementation, the insulating dielectric layer does not contain fiberglass cloth, and the thickness of the insulating dielectric layer ≤ 2 mil.
[0030] In a second aspect, the present application provides a thick copper printed circuit board, which is manufactured by the method described in the first aspect.
[0031] A thick copper printed circuit board processing method and a thick copper printed circuit board provided by the embodiments of the present application have the following technical effects:
[0032] This solution changes the existing method of single-etching through thick copper to two symmetric etchings, distributes the etching amount of thick copper to two operations, significantly reduces the single-etching depth, thereby reducing the influence of the etching factor, improving the accuracy of line width and line pitch, and avoiding short-circuit problems caused by burrs and incomplete etching. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] The accompanying drawings herein are incorporated into the specification and form a part of the specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.
[0034] Figure 1 Schematic flow chart of the thick copper printed circuit board processing method provided by the embodiments of the present application Figure 1 ;
[0035] Figure 2 Schematic flow chart of the thick copper printed circuit board processing method provided by the embodiments of the present application Figure 2 ;
[0036] Figure 3 Schematic diagram of the processing method of a thick copper printed circuit board provided by an embodiment of the present application;
[0037] Figure 4 Schematic diagram of a multi-layer circuit core board provided by an embodiment of the present application.
[0038] Through the above-mentioned drawings, specific embodiments of the present application have been shown, and there will be more detailed descriptions hereinafter. These drawings and text descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. Detailed implementation manners
[0039] Here, exemplary embodiments will be described in detail, and examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The implementation manners described in the following exemplary embodiments do not represent all implementation manners consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.
[0040] In the existing processing method of thick copper printed circuit boards, since the thick copper layer is directly penetrated in a single etching, the following defects are likely to occur during the processing:
[0041] 1. There is a large difference in the width between the top and bottom of the line (for example, if the designed line width is 3 mil, the actual bottom of the line may reach 5 mil);
[0042] 2. The side wall of the circuit is trapezoidal, and the etching residue causes a risk of short circuit;
[0043] 3. The yield of single etching for copper thickness above 10 OZ is relatively low.
[0044] The root cause of the above-mentioned defects is the limitation of the etching factor. The etching factor = etching depth / lateral etching amount. For thick copper (such as 10 OZ ≈ 350 μm), during single etching, the etching solution needs to vertically penetrate the copper layer and at the same time diffuse laterally, resulting in an exponential increase in the lateral etching amount with the copper thickness. And due to the decrease in the concentration of the etching solution at the bottom of the thick copper layer, the etching rate at the bottom is reduced, resulting in the defects of over-etching at the top and insufficient etching at the bottom.
[0045] The inventors consider that if the single etching amount in the prior art is amortized to two times, and symmetrical etching is performed twice on both sides of the thick copper layer, the etching that penetrates the thick copper layer can also be completed, and because the single etching depth is low, the above-mentioned defects can be avoided. Therefore, the technical concept of the present application is: anti-etching treatment is performed on one side of the thick copper core board to protect the surface, and etching is performed on the opposite side of the film surface according to the designed circuit pattern, and the etching does not penetrate the copper layer of the core board to form an etched circuit. Anti-etching treatment is performed on the side that has been etched, the anti-etching protective film that was initially applied is removed, and symmetrical etching is performed on this side according to the same circuit pattern, that is, the circuits etched on the two opposite sides of the core board are symmetrical, and the last etching penetrates the copper layer of the thick copper core board to form a thick copper circuit core board.
[0046] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.
[0047] Embodiment 1
[0048] Figure 1 Schematic diagram of the thick copper printed circuit board processing method provided in the embodiment of the present application Figure 1 ,like Figure 1 As shown, the method includes:
[0049] S101, performing an anti-etching treatment on a first surface of the thick copper core board to form a first anti-etching protection layer;
[0050] Since the thick copper core board needs to process the double-sided circuits in steps and avoid mutual interference, this step provides a physical isolation basis for subsequent single-sided etching by setting an anti-etching protective layer on the first surface. In specific implementation, the anti-etching treatment can be applied by, for example, applying an anti-etching protective film or a liquid resist coating: the anti-etching protective film (such as a dry film) can be combined with the copper surface through a hot pressing process to form an anti-etching protective layer, and the liquid resist can be sprayed / spin-coated to cover the surface and then cured by ultraviolet to form an anti-etching protective layer.
[0051] S102, performing a first single-sided treatment on a second surface of the thick copper core board, the second surface being an opposite surface of the first surface, the single-sided treatment comprising: etching the surface of the thick copper core board according to a circuit pattern to form an etched circuit; in the first single-sided treatment, etching does not penetrate the copper layer of the thick copper core board;
[0052] Since single - step full - etching of thick copper (≥10OZ) is likely to cause the etching factor to get out of control (excessive difference between the line surface and the line bottom), a phased etching strategy is adopted in this step: First, perform the first etching on the second surface. For example, an acidic etching solution (such as a sulfuric acid - hydrogen peroxide system) or a basic etching solution (such as an ammonia - copper chloride system) can be used. By controlling the etching time, temperature, and solution concentration, the etching depth reaches the target line width but does not completely penetrate the copper layer. In this stage of etching, for example, half of the original copper thickness can be retained as a support layer, thus avoiding circuit burrs caused by the penetration of the etching solution to the edge of the first - surface protective film, and at the same time reducing the risk of core - board warping caused by an overly thin copper layer, providing stable physical support for subsequent symmetric etching. In practical applications, different etching depths can be selected according to requirements. For example, if the etching ability is within 5OZ copper thickness, the etching depth of a single - step etching can be selected within 5OZ.
[0053] S103. Remove the first anti - etching protective layer, perform anti - etching treatment on the second surface, and form a second anti - etching protective layer;
[0054] Since the first surface needs to be etched twice while the second surface has completed the first treatment, the first anti - etching protective layer is removed to etch the first surface. Specific operations can include, for example: First, soak and strip the dry - film protective layer on the first surface with a basic solution (such as 3% - 5% sodium hydroxide), or dissolve the liquid resist with an organic solvent (such as acetone); then immediately re - apply a protective film (such as a low - temperature hot - press - attached anti - static dry film) or re - spray a liquid resist on the second surface that has completed the first etching to prevent damage to its formed circuit during subsequent processes.
[0055] S104. Perform the second single - side treatment on the first surface of the thick - copper core board. The etching lines formed by the first single - side treatment and the second single - side treatment are symmetric on both sides of the thick - copper core board. In the second single - side treatment, etch through the copper layer of the thick - copper core board;
[0056] In this step, the copper layer is etched through symmetrically to finally form the circuit structure of the thick - copper core board. Specifically, in the second etching, for example, the same or stronger etching parameters as the first time can be used (such as increasing the etching - solution concentration to 1.2 - 1.5 times, extending the etching time by 30% - 50%) until the remaining copper layer is completely etched through, making the etching line formed by the first etching and the etching line formed by the second etching form a mirror symmetry.
[0057] S105. Remove the second anti - etching protective layer to form a circuit core board.
[0058] In this step, the final forming of the core board is completed by removing the remaining anti - etching protective layer. Specifically, the same stripping process as in step S103 can be used to remove the second anti - etching protective layer.
[0059] The technical effect of this embodiment is as follows: This solution changes the existing method of single - time etching through thick copper to two - time symmetric etching, distributes the etching amount of thick copper to two operations, significantly reduces the single - time etching depth, thereby reducing the influence of the etching factor, improving the accuracy of line width and line spacing, and avoiding short - circuit problems caused by burrs and incomplete etching.
[0060] Embodiment Two
[0061] The existing production process of thick - copper printed circuit boards still has the following defects:
[0062] 1. In the horizontal transmission production line, the thick - copper core board bends and jams due to uneven weight distribution.
[0063] 2. The substrate in the copper - free area tears and the board is damaged due to the impact of the brownization bath liquid.
[0064] 3. During the lamination process, the connecting PP (pre - impregnated material) cannot completely fill the line gaps of the thick - copper core board, and air bubbles remain in the line gaps.
[0065] 4. It is impossible to reduce the thickness of the insulating dielectric layer of the multi - layer core board to less than 2 mil.
[0066] The root causes of defects 1 and 2 are that after the thick - copper core board is etched, the weight distribution is unbalanced, the weight difference between the copper - containing area and the copper - free area is huge, and the rigidity of the thick - copper area is high while the flexibility of the copper - free area is large. During horizontal transmission, due to gravity sagging, stress concentration occurs, which easily leads to substrate fracture.
[0067] The root causes of defects 3 and 4 are as follows: In the existing production process of thick - copper printed circuit boards, it is necessary to stack the circuit core boards and the connecting PP alternately. The connecting PP is located between two circuit core boards. Through lamination, the epoxy resin impregnated in the connecting PP fills into the line gaps as an insulating protective layer, and the connecting PP acts as the insulating dielectric layer between the two circuit core boards. As a semi - cured sheet material made of glass fiber cloth impregnated with epoxy resin, the resin fluidity of the connecting PP is relatively low. During the lamination process, the epoxy resin cannot completely fill into the line gaps, and the glass fiber cloth also hinders the epoxy resin from filling the line gaps. Moreover, since the thickness of the thinnest glass fiber cloth is 1.8 mil, plus the resin layers on both sides of the glass fiber cloth, it is impossible to reduce the thickness of the insulating dielectric layer to less than 2 mil.
[0068] Based on Embodiment One, this embodiment solves the above - mentioned defects of the existing technology by laminating a fluid - type insulating protector on the etched surface after etching, so that the fluid - type insulating protector fills into the etched lines and covers the etched surface.
[0069] Figure 2 Schematic flow of the processing method of the thick - copper printed circuit board provided by the embodiment of the present application Figure 2 as Figure 2As shown in the figure, the method includes:
[0070] S201. Perform an anti-etching treatment on the first surface of the thick copper core board to form a first anti-etching protection layer;
[0071] S202. Perform a first single-sided treatment on the second surface of the thick copper core board. The second surface is the opposite surface of the first surface. The single-sided treatment includes: etching the surface of the thick copper core board according to the circuit pattern to form an etched circuit, and laminating a flowable insulating protective material on the etched surface of the thick copper core board that has not undergone the anti-etching treatment, so that the flowable insulating protective material fills into the etched circuit and covers the etched surface to form an insulating protection layer. The etched surface is the surface of the thick copper core board after etching; in the first single-sided treatment, the etching does not penetrate the copper layer of the thick copper core board;
[0072] Specifically, the etching in Example 1 can be used to complete the etching. The flowable insulating protective material can be selected from materials with relatively high fluidity, such as pure glue or benzoxazine resin. Among them, pure glue is a non-glass fiber-reinforced prepreg material, which consists of the following components:
[0073] Resin matrix: epoxy resin or polyimide (PI), accounting for 85%-95%;
[0074] Filler: silica (particle size 0.5-5μm, accounting for 5%-15%), used to adjust CTE and thermal conductivity;
[0075] Additives: flame retardants (such as phosphorus-based), toughening agents (such as rubber particles), etc.
[0076] When pure glue is selected as the flowable insulating protective material, the following process flow can be adopted:
[0077] 1. Surface treatment:
[0078] After etching, the copper surface is chemically micro-etched to improve the adhesion of pure glue;
[0079] The residual etching solution is removed by washing with deionized water;
[0080] 2. Coat pure glue on the etched surface. For example, the coating thickness can be controlled by slit extrusion coating, and the bubbles are eliminated through a vacuum defoaming process to avoid filling defects.
[0081] 3. Use a vacuum laminator to perform a lamination treatment on the pure glue, so that the pure glue fills into the etched circuit and covers the etched surface;
[0082] Perform a thermal curing treatment on the pure glue to form an insulating protection layer. The thermal curing treatment can include a first-stage pre-curing and a second-stage complete curing.
[0083] When benzoxazine resin is selected as the flowable insulation protector, vinyl siloxane can be added to the benzoxazine resin to reduce its viscosity, and dicyandiamide (DICY) can be added to promote the low-temperature curing performance of the benzoxazine resin. The following technological process can be adopted:
[0084] 1. Spray the benzoxazine resin onto the etched surface by spraying process, and press the benzoxazine resin through a vacuum laminator so that the benzoxazine resin fills into the etched circuit and covers the etched surface;
[0085] 2. Cure the benzoxazine resin. For example, the curing of the benzoxazine resin can be completed by a low-temperature curing process, or the hardness of the benzoxazine resin can be further improved by an ultraviolet post-curing process.
[0086] The technical effect of this step is that by single-sided etching, the copper layer on the unetched side is retained as a support structure, significantly improving the rigidity of the core board and ensuring its balance and stability during horizontal transmission. The bending or jamming phenomenon caused by uneven weight distribution can be avoided. Pressing the flowable insulation protector immediately after etching can form a protective layer covering the etched surface. On the one hand, the protective layer can play a certain physical support role, and on the other hand, it can isolate the direct impact of the brownization solution on the substrate, enhance the tear resistance of the substrate, and effectively reduce the risk of defective boards. Moreover, by utilizing the high-flowability characteristics of materials such as pure glue and benzoxazine resin, the etched circuit gaps are pre-filled before the core board is laminated to form a dense insulation protective layer, thus avoiding the problem that the connecting PP cannot completely fill the circuit gaps during multi-layer lamination in the prior art and greatly reducing the bubble residue. And since an insulation protective layer has been pre-formed on the etched surface, a connecting PP containing fiberglass cloth does not need to be used in the multi-layer lamination step, so an ultra-thin insulation dielectric layer can be used for lamination.
[0087] S203. Remove the first anti-etching protective layer, and attach an anti-etching protective film to the surface of the insulation protective layer at the second surface as the second anti-etching protective layer;
[0088] Specifically, since the first surface needs to be etched and the insulation protective layer has been formed on the second surface, the specific operations can include, for example: first soak or plasma etch the first surface anti-etching protective layer with an alkaline solution (such as 5% sodium hydroxide) to expose the original copper surface; then perform a surface activation treatment (such as UV ozone cleaning for 10 minutes or micro-etching solution treatment for 30 seconds) on the insulation protective layer of the second surface, and then attach a dry film type anti-etching protective film at a temperature of 80 - 100 °C through a roller press, or form a liquid photoresist layer by spraying.
[0089] S204. Perform a second single-sided treatment on the first surface of the thick copper core board. The etched circuits formed by the first single-sided treatment and the second single-sided treatment are symmetric on both sides of the thick copper core board. In the second single-sided treatment, etch through the copper layer of the thick copper core board;
[0090] S205. Remove the second anti-etching protective layer to form a circuit core board.
[0091] Figure 3 Schematic diagram of the processing method of the thick copper printed circuit board provided by the embodiment of the present application. As Figure 3 shown, after the original thick copper core board completes the first single-sided treatment, an anti-etching protective film is attached to the first surface, and a fluid insulating protective material forms an insulating protective layer to form the thick copper core board at A. After completing the first single-sided treatment, an anti-etching protective film is attached to the insulating protective layer on the second surface, and the second single-sided treatment is performed on the first surface to form mirror-symmetric etched circuits and penetrate the thick copper layer to obtain the thick copper core board at B. In practical applications, an anti-etching protective film can also be attached to the surface of the insulating protective layer on the first surface. Finally, both anti-etching protective films on both sides are removed to obtain Figure 3 the circuit core board at C in
[0092] Figure 4 Schematic diagram of the multi-layer circuit core board provided by the embodiment of the present application. As Figure 4 shown is a multi-layer circuit core board formed by laminating 4-layer circuit core boards. An insulating dielectric layer is provided between two adjacent circuit core boards. An insulating dielectric layer is also provided outside the outermost circuit core board for bonding the outer copper foil. Specifically, a plurality of circuit core boards and a plurality of insulating dielectric layers are alternately stacked, and the alternately stacked plurality of circuit core boards and a plurality of insulating dielectric layers are laminated and wrapped with the outer copper foil to form a multi-layer circuit core board. Optionally, the insulating dielectric layer can be a semi-solid sheet made of epoxy resin, or can be a semi-cured sheet made of polytetrafluoroethylene, and the insulating dielectric layer does not contain fiberglass cloth and has a thickness ≤ 2 mil.
[0093] In a possible embodiment of the present application, a thick copper printed circuit board is provided, and the thick copper printed circuit board is processed by the foregoing method.
[0094] Finally, it should be noted that: After considering the specification and practicing the invention disclosed herein, those skilled in the art will easily think of other embodiments of the present invention. The present invention is intended to cover any variations, uses, or adaptations of the present invention, which follow the general principles of the present invention and include common general knowledge or conventional technical means in the technical field not disclosed in the present invention. It is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of the present invention is only limited by the appended claims.
Claims
1. A method for processing a thick copper printed circuit board, characterized in that: The method comprises: Performing an anti-etching treatment on the first surface of the thick copper core board to form a first anti-etching protection layer; A first single-sided treatment is performed on the second surface of the thick copper core board, the second surface being the opposite surface of the first surface, the single-sided treatment comprising: etching the surface of the thick copper core board according to the circuit pattern to form an etched circuit; in the first single-sided treatment, the etching does not penetrate the copper layer of the thick copper core board; removing the first anti-etching protection layer, and performing the anti-etching treatment on the second surface to form a second anti-etching protection layer; Performing the second single-sided treatment on the first surface of the thick copper core board, the etching circuits formed by the first single-sided treatment and the second single-sided treatment are symmetrical on both sides of the thick copper core board, and in the second single-sided treatment, etching penetrates the copper layer of the thick copper core board; The second anti-etching protection layer is removed to form a circuit core board.
2. The method according to claim 1, characterized in that After etching the surface of the thick copper core board according to the circuit pattern to form an etched circuit, the single-side processing further includes: A fluid insulating protector is pressed onto the etched surface of the thick copper core board that has not undergone the anti-etching treatment, so that the fluid insulating protector fills the etched circuit and covers the etched surface to form an insulating protective layer. The etched surface is the surface of the thick copper core board after etching.
3. The method according to claim 2, characterized in that The fluid insulating protective material is pressed on the etching surface of the thick copper core board that has not been subjected to the anti-etching treatment, so that the fluid insulating protective material fills the etching circuit and covers the etching surface to form an insulating protective layer, and the etching surface is the surface of the thick copper core board after etching, including: Applying pure glue on the etched surface; Performing a pressing process on the pure glue so that the pure glue fills the etching circuit and covers the etching surface; The pure glue is subjected to heat curing treatment to form the insulating protective layer.
4. The method according to claim 2, characterized in that: The fluid insulating protector is pressed on the etching surface of the thick copper core board that has not been subjected to the anti-etching treatment, so that the fluid insulating protector fills the etching circuit and covers the etching surface to form an insulating protective layer, and the etching surface is the surface of the thick copper core board after etching: spraying benzoxazine resin onto the etched surface; Performing a lamination process on the benzoxazine resin so that the benzoxazine resin fills the etched circuit and covers the etched surface; The benzoxazine resin is cured to form the insulating protection layer.
5. The method according to claim 2, characterized in that: The step of performing the anti-etching treatment on the second surface to form a second anti-etching protection layer comprises: The surface of the insulating protection layer at the second surface is covered with an anti-etching protection film as the second anti-etching protection layer.
6. The method according to any one of claims 2 to 5, characterized in that: After removing the second anti-etching protection layer to form a circuit core board, the method further includes: Alternately stacking a plurality of the circuit core boards and a plurality of insulating medium layers, with the insulating medium layer being disposed between the insulating protection layers of two adjacent circuit core boards; The multiple circuit core boards and multiple insulating medium layers stacked alternately are pressed together to form a multi-layer circuit core board.
7. The method according to claim 6, characterized in that The insulating medium layer is a prepreg made of epoxy resin.
8. The method according to claim 6, characterized in that The insulating medium layer is a prepreg made of polytetrafluoroethylene.
9. The method according to claim 7 or 8, characterized in that: The insulating medium layer does not contain glass fiber cloth, and the thickness of the insulating medium layer is ≤2 mil.
10. A thick copper printed circuit board, characterized in that: The thick copper printed circuit board is manufactured by the method described in any one of claims 1-9.