A structure and design method for increasing the current flow of a PCB at low cost

Abstract

The application relates to a low-cost structure and design method for increasing the throughflow of a PCB and belongs to the technical field of PCB design and manufacturing. The application comprises the following steps: a multilayer PCB circuit board is used as a basic carrier of a throughflow structure; a first thick copper core plate is pressed and combined at the center position of the multilayer PCB circuit board, and first circuit grooves are formed in the copper foil areas on the two sides of the first thick copper core plate; a residual copper layer is arranged at the bottom of the first circuit grooves, and the residual copper layer is etched to form second circuit grooves; a resin layer is filled in the second circuit grooves, and the resin layer is polished to be flush with the surface of the first thick copper core plate; common copper thick core plates are distributed in the multilayer PCB circuit board at intervals; prepregs are arranged at the gaps between the first thick copper core plates and the common copper thick core plates; and PCB surface copper is arranged on the outermost layer of the multilayer PCB circuit board and is attached to the prepregs. The application is used for solving the design bottleneck of the throughflow capacity of a PCB in the prior art and realizing a design process.

Description

Technical Field

[0001] This invention belongs to the field of PCB design and manufacturing technology, and specifically relates to a low-cost structure and design method for increasing PCB current flow. Background Technology

[0002] With the development of artificial intelligence and the significant increase in computing power, high-performance CPUs / GPUs are needed. These chips require more high-speed signal channels, increasing the number of PCB layers and thickness. Furthermore, these high-performance chips consume more power, operating at or near maximum power consumption during AI calculations. This necessitates higher current-carrying capacity from the PCB, placing a significant strain on the PCB's power supply system. Existing technologies increase current-carrying capacity by increasing the width of power conductors, increasing copper foil thickness, increasing the number of PCB layers, and adding copper strips to the PCB surface for soldering or crimping connections.

[0003] The existing technology has at least the following problems in its use: High-performance chips generally require more channels for high-speed signal lines, which will squeeze limited PCB resources and is not conducive to PCB routing design. Furthermore, as the number of PCB layers increases or the copper thickness increases, the difficulty and processing cycle of traditional etching processes will be higher. Adding copper strips to the PCB surface and connecting them to the PCB by soldering or pressing to increase current flow will increase the surface area and volume of the PCB. Summary of the Invention

[0004] This invention provides a low-cost structure and design method for increasing the current carrying capacity of PCBs, which solves the design bottleneck of current carrying capacity of PCBs in the prior art and the process method for realizing the design.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solution: A low-cost structure for increasing PCB current flow includes: a multilayer PCB circuit board as the basic carrier of the current flow structure; a first thick copper core board, pressed at the center of the multilayer PCB circuit board stack, the first thick copper core board having a thickness ≥10mil, and first line grooves formed on the copper foil areas on both sides of the first thick copper core board; a residual copper layer, disposed at the bottom of the first line groove, the residual copper layer being etched to form a second line groove; a resin layer, filling the second line groove, the resin layer being polished to be flush with the surface of the first thick copper core board; a common thick copper core board, distributed at intervals with the first thick copper core board within the multilayer PCB circuit board; a prepreg, disposed in the gap between the first thick copper core board and the common thick copper core board; and PCB surface copper, disposed on the outermost layer of the multilayer PCB circuit board, bonded to the prepreg.

[0006] Furthermore, the first thick copper core board is made by pressing glass fiber cloth and copper foil arranged symmetrically on the upper and lower sides together. The thickness of the residual copper layer is ≤4mil. The first thick copper core board is also provided with insulating drill holes, and the insulating drill holes are also filled with the resin layer. The resin layer is tightly attached to the inner wall of the insulating drill holes.

[0007] Furthermore, the prepreg is also disposed between the ordinary thick copper core board and the copper surface of the PCB. The first thick copper core board and the adjacent prepreg are bonded together using a low-adhesion prepreg or a thin prepreg. The surface of the ordinary thick copper core board is etched with a circuit layer, and both the surface of the first thick copper core board and the ordinary thick copper core board are provided with a browning layer, which is used to increase the adhesion with the prepreg.

[0008] Furthermore, based on the above-mentioned low-cost PCB current-carrying structure, this invention also proposes a low-cost design method for increasing PCB current-carrying capacity, comprising the following steps: Step 1, preparing and obtaining a first thick copper core board, a regular thick copper core board, a prepreg, and PCB surface copper with matching specifications; Step 2, processing the copper foil on both sides of the first thick copper core board to form a first line groove and retaining the residual copper layer at the bottom; Step 3, using an etching process to remove the residual copper layer, so that the first line groove forms a second line groove; Step 4, filling the second line groove and insulating drill hole with resin, and after curing and polishing, forming a brown layer on the surface of the first thick copper core board; Step 5, performing line etching processing on the regular thick copper core board, and forming a brown layer on its surface after completion; Step 6, sequentially stacking and pressing the browned first thick copper core board, the regular thick copper core board, the prepreg, and the PCB surface copper to form a first circuit board; Step 7, performing subsequent molding processing on the first circuit board to obtain a target PCB circuit board with high current-carrying capacity.

[0009] Furthermore, in step 2, before processing the first line groove, positioning holes and laser mark points are first opened on the edge of the first thick copper core board. The first thick copper core board is fixed on the worktable of the processing equipment by a fixture to ensure that the warpage of the first thick copper core board is ≤1mil. Then, the first line groove is processed by laser engraving or milling. After processing one side of the copper foil, the first thick copper core board is flipped over and re-fixed. The same specification first line groove is processed on the other side of the copper foil.

[0010] Furthermore, in step 3, an acid etching process or an alkaline etching process is selected to remove the residual copper layer based on the depth and width dimensions of the second line groove.

[0011] Furthermore, in step 4, resin ink is pressed into the second line groove and insulating drill hole by a scraper. The angle, speed and pressure of the scraper are precisely controlled to ensure full filling without air bubbles. First, pre-curing is carried out by segmented ultraviolet light irradiation combined with stepped heating. Then, the resin overflowing from the board surface is removed by sanding with a sanding belt or non-woven cloth abrasive board so that the resin layer is flush with the surface of the first thick copper core board. Finally, the first thick copper core board is subjected to browning treatment to form a browning layer.

[0012] Furthermore, in step 6, the first thick copper core board after browning, the ordinary thick copper core board, the prepreg, and the PCB copper are stacked sequentially according to the stacking design requirements, and the pressing process is used to make each layer tightly bonded to form an integrated first circuit board.

[0013] Furthermore, in step 7, the subsequent forming process includes drilling, electroplating, circuit forming, solder resist, surface treatment and shape forming in sequence. The surface of the target PCB circuit board after forming is coated with a green solder mask layer, and the through holes on the circuit board are provided with a green solder mask plugging structure.

[0014] This invention provides a low-cost structure and design method for increasing PCB current carrying capacity. The advantages are as follows: By laminating a first thick copper core board to the center of a multilayer PCB stack and limiting its thickness to ≥10mil, the basic current carrying capacity of the PCB is significantly improved without increasing PCB wiring and structural space, thus meeting the high power consumption requirements of high-performance chips. By creating circuit grooves in the first thick copper core board and then etching, resin filling, and polishing, the surface flatness of the thick copper core board is ensured, preventing the thick copper structure from affecting subsequent lamination processes. Simultaneously, the design of a residual copper layer thickness ≤4mil prevents damage to the core board's insulation material. Furthermore, by setting a browning layer on the surfaces of the first thick copper core board and a regular thick copper core board, and using low-adhesion adhesive on adjacent sides of the first thick copper core board... Thin prepregs effectively enhance adhesion between layers, ensuring the structural stability of multilayer PCBs. The first thick copper core board circuitry is processed using a combination of laser engraving / milling and etching, replacing the traditional method of simply increasing copper foil thickness. This reduces the processing difficulty and production cycle of thick copper circuitry, achieving a low-cost increase in current carrying capacity. Resin-filled insulating drill holes and second circuit grooves, along with subsequent solder mask coating and via plugging, further ensure the PCB's insulation performance, preventing short-circuit risks. By processing and browning the thick and ordinary copper core boards in stages before laminating them together, the PCB processing flow is adapted to existing production equipment, eliminating the need for additional dedicated processing devices and further reducing production modification costs. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the structure of the thick copper core board to be processed according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the first line groove processing according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the second line groove processing according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the resin plug groove processing according to an embodiment of the present invention; Figure 5 This is a schematic diagram of the conventional copper thick core board circuit processing according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the pressing process according to an embodiment of the present invention; Figure 7 This is the target circuit board in an embodiment of the present invention; Figure 8 A flowchart of the production steps for thick copper lines in a PCB is provided for embodiments of the present invention.

[0017] In the diagram: 201 - Fiberglass cloth for thick copper core board; 202 - Copper foil for thick copper core board; 301 - First circuit groove; 302 - Insulation drill hole; 303 - Residual copper in circuit groove; 401 - Second circuit groove; 501 - Resin; 601 - Fiberglass cloth for ordinary thick copper core board; 602 - Copper foil for ordinary thick copper core board; 701 - PCB surface copper; 702 - Prepreg; 703 - Fiberglass cloth for laminated thick copper core board; 704 - Fiberglass cloth for laminated ordinary thick copper core board; 801 - Green solder mask on PCB surface; 802 - Green solder mask plug; 803 - Insulation via for thick copper core board. Detailed Implementation

[0018] The embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0019] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0020] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0021] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to welding, bolting, or riveting; they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0022] Example: like Figures 1 to 8 As shown, this embodiment provides a low-cost structure and design method for increasing PCB current flow. The low-cost PCB current flow structure includes: a multilayer PCB circuit board as the basic carrier of the current flow structure; a first thick copper core board, pressed at the center of the multilayer PCB circuit board, the thickness of the first thick copper core board being ≥10mil, and first line grooves 301 formed on the copper foil areas on both sides of the first thick copper core board; a residual copper layer, disposed at the bottom of the first line groove 301, the residual copper layer being etched to form a second line groove 401; a resin layer, filling the second line groove 401, the resin 501 being polished to be flush with the surface of the first thick copper core board; a common thick copper core board, distributed at intervals with the first thick copper core board in the multilayer PCB circuit board; a prepreg 702, disposed in the gap between the first thick copper core board and the common thick copper core board; and PCB surface copper 701, disposed on the outermost layer of the multilayer PCB circuit board, and attached to the prepreg 702. In this embodiment, based on the actual usage requirements of PCBs in the server and automotive fields, the first thick copper core board is determined to be the core current-passing structure of the multilayer PCB circuit board. The number of ordinary thick copper core boards, prepreg 702, and PCB surface copper 701 can be adjusted according to the complexity of the PCB circuit. In this embodiment, there are 2 ordinary thick copper core boards, 4 prepregs 702, and 2 PCB surface copper 701, which are symmetrically distributed on the inner and outer layers of the multilayer PCB circuit board.

[0023] Furthermore, the first thick copper core board is formed by pressing together the glass fiber cloth 201 of the thick copper core board and the copper foil 202 of the thick copper core board arranged symmetrically on both sides. The residual copper layer is the residual copper 303 of the circuit groove, with a thickness of ≤4mil. The first thick copper core board also has insulating drill holes 302, which are filled with the resin 501. The resin 501 is tightly attached to the inner wall of the insulating drill hole 302. In this embodiment, the copper foil 202 of the thick copper core board of the first thick copper core board is a symmetrically arranged thick copper structure. The glass fiber cloth 201 of the thick copper core board is the insulating substrate of the copper foil. When processing the first circuit groove 301, the thickness of the residual copper 303 of the circuit groove is strictly controlled not to exceed 4mil. This ensures the operability of the subsequent etching process and avoids damage to the insulation performance of the glass fiber cloth 201 of the thick copper core board due to over-processing. The insulating drill hole 302 and the first circuit groove 301 are processed and formed in the same batch. The resin 501 can fill both at the same time to ensure the consistency of filling.

[0024] Furthermore, the prepreg 702 is also disposed between the ordinary thick copper core board and the PCB surface copper 701. The first thick copper core board and the adjacent prepreg 702 are bonded using a low-adhesion prepreg or a thin prepreg. The surface of the ordinary thick copper core board is etched with a circuit layer, and both the first thick copper core board and the ordinary thick copper core board have a browning layer on their surfaces. The browning layer is used to increase the adhesion with the prepreg 702. In this embodiment, the prepreg 702 is an adhesive structure for a multilayer PCB circuit board, disposed between each core board and between the core board and the PCB surface copper 701. Because the surface of the first thick copper core board is smooth after being filled and polished with resin 501, the use of low-adhesion or thin prepreg 702 on its adjacent sides can ensure the bonding effect. The circuit layer of the ordinary thick copper core board is a conventional signal circuit, and the etching process is consistent with existing PCB circuit processing. The browning layer is a roughened oxide layer, which can effectively increase the surface roughness of the core board and improve the bonding force with the prepreg 702.

[0025] Furthermore, based on the above structure, the low-cost design method for increasing PCB current flow in this embodiment includes the following steps: Step 1: Prepare and obtain the first thick copper core board, ordinary thick copper core board, prepreg 702 and PCB surface copper 701 with matching specifications respectively; Step 2: Process the copper foil 202 on both sides of the first thick copper core board to form the first line groove 301 and retain the residual copper 303 of the line groove at the bottom. Step 3: Use an etching process to remove the residual copper 303 in the line groove, so that the first line groove 301 forms the second line groove 401; Step 4: Fill the second line groove 401 and the insulating drill hole 302 with resin 501. After curing and polishing, a browning layer is formed on the surface of the first thick copper core board. Step 5: Perform circuit etching on the ordinary copper thick core board, and form a brown layer on its surface after completion; Step 6: The first thick copper core board after browning, the ordinary thick copper core board, the prepreg 702, and the PCB copper 701 are sequentially stacked and pressed together to form the first circuit board. Step 7: Perform subsequent molding processing on the first circuit board to obtain a target PCB circuit board with high current carrying capacity.

[0026] In this embodiment, each step is a continuous processing flow. The finished product of the previous step is the base material for the subsequent step. All processing specifications are determined in advance according to the design requirements of the PCB to ensure the specification matching of each component. Moreover, the entire processing flow is compatible with existing PCB production equipment and no new special equipment is required.

[0027] In this embodiment, the specific production steps for the thick copper lines of the PCB are as follows: Figure 8 As shown: S100: The first thick copper core board is made by laminating the fiberglass cloth 201 of the thick copper core board and the copper foil 202 of the thick copper core board with symmetrical thicknesses on both sides. Generally, the thickness of the copper foil 202 of the thick copper core board is ≥10mil, and the specific thickness is set according to product requirements; the core board with ordinary copper thickness, the prepreg 702, and the PCB surface copper 701 are set according to the actual quantity. In this specific implementation case, there are 2 pieces of ordinary copper thick core board, 4 pieces of prepreg 702, and 2 pieces of PCB surface copper 701.

[0028] S200: Put Figure 2 The first thick copper core plate was processed into Figure 3 A thick copper core board with a first line groove 301 and an insulating drill hole 302.

[0029] Before processing the thickest copper core board, positioning holes and laser mark points should be added to the edges. The thick copper core board to be processed should be fixed on the worktable of the processing equipment using a fixture to ensure that the warpage of the core board is ≤1mil and that there is no displacement or movement during the processing of the thick copper core board. The mark points are positioned and compensated by the vision recognition system of the equipment to confirm the zero point position of the processing.

[0030] Before processing the copper foil 202 on the thick copper core board, the processing path should be converted according to the design requirements. The corresponding parameters should be set. For processing, a milling machine can be used for precision engraving; key control parameters include cutting speed, spindle speed, and depth of cut. If laser cutting is chosen, key optical control parameters include laser power, cutting speed, focal point position, and gas pressure.

[0031] There are technical requirements for obtaining the first line groove 301: it must not damage the glass fiber cloth 201 of the thick copper core board, and the thickness of the residual copper 303 in the line groove of the first line groove 301 should be ≤4mil.

[0032] After processing the copper foil 202 on one side of the thick copper core board, the circuit board is flipped over, and the thick copper on the opposite side is fixed upwards on the processing table. Then, the mark points are identified, and a second processing is performed.

[0033] S300: The residual copper 303 in the circuit groove is removed by etching technology to form the second circuit groove 401. The etching can be acidic or alkaline depending on the depth and width of the groove.

[0034] S400: For filling the second line groove 401 and insulating drill hole 302 with resin 501, a scraper presses the resin ink into the second line groove 401 and insulating drill hole 302. The scraper angle, speed, and pressure need to be precisely controlled to ensure full filling without air bubbles. Pre-curing: Ultraviolet (UV) light is used for segmented irradiation, specifically starting with short wavelengths and then increasing to longer wavelengths, combined with stepped heating, specifically gradually increasing from 100°C to 120°C. This effectively removes air bubbles and prevents subsequent board bursting. Grinding and polishing: The board is sanded with a sanding belt or non-woven fabric to remove excess resin 501, ensuring an absolutely smooth surface. Grinding and polishing: The board is sanded with a sanding belt or non-woven fabric to remove excess resin 501, ensuring an absolutely smooth surface.

[0035] S500: Browning the circuit surface to increase adhesion between the circuit and the prepreg 702.

[0036] S700: Subsequently, the browned first thick copper core board, the browned ordinary thick copper core board, the prepreg 702, and the PCB copper 701 are laminated to form the first circuit board. Since the surface of the first thick copper core board is flat and smooth, the adjacent sides can use low-adhesion or thinner prepreg 702.

[0037] S800: The target circuit board is obtained after the first circuit board is drilled, electroplated, wire forming, solder masking, surface treatment, and molding. For example... Figure 7 As shown, the relative positions of the green solder mask 801, green solder mask plug 802, and thick copper core board insulating via 803 on the PCB surface are expressed in sequence.

[0038] In summary, this invention significantly improves the current-carrying capacity of a multilayer PCB by placing a thick copper core board at the center of the PCB stack and defining its thickness, without occupying additional space, thus meeting the high power consumption requirements of high-performance chips. The thick copper circuitry is processed using a combination of laser engraving / milling and etching, along with resin 501 filling and polishing, reducing the processing difficulty of thick copper PCBs and avoiding the high costs and long processing cycles associated with traditional methods of increasing copper foil thickness. By setting a browning layer on the core board surface and using a suitable 702 prepreg, the structural stability of the multilayer PCB is ensured, and the adhesion between layers is improved. The step-by-step processing and overall lamination process design allows the entire solution to be compatible with existing PCB production equipment, further reducing production modification costs. The double insulation treatment of resin 501 filling and green solder mask plugging ensures the insulation performance of the thick copper PCB, avoiding the risk of short circuits. The structure and design method of this invention balance the needs of improved PCB current-carrying capacity, reduced processing difficulty, and controlled production costs, while not occupying additional wiring or structural space. It can be widely applied to the production of complex PCB circuits in fields such as servers and automobiles.

[0039] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope described in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A low-cost structure for increasing current flow through a PCB, characterized in that, include: A multilayer PCB circuit board serves as the basic carrier for the current-carrying structure. A first thick copper core board is laminated at the center of the multilayer PCB circuit board stack, with a thickness ≥10 mil. First circuit grooves are formed on both sides of the copper foil area. A residual copper layer is disposed at the bottom of the first circuit groove, and the residual copper layer is etched to form a second circuit groove. A resin layer is filled in the second circuit groove, and the resin layer is polished to be flush with the surface of the first thick copper core board. Ordinary thick copper core boards are distributed in the multilayer PCB circuit board at intervals from the first thick copper core board. A prepreg is disposed in the gap between the first thick copper core board and the ordinary thick copper core board. PCB surface copper is disposed on the outermost layer of the multilayer PCB circuit board and is bonded to the prepreg.

2. The structure for increasing PCB current flow at low cost according to claim 1, characterized in that, include: The first thick copper core board is made of glass fiber cloth and copper foil arranged symmetrically on the top and bottom. The thickness of the residual copper layer is ≤4mil. The first thick copper core board is also provided with insulating drill holes. The insulating drill holes are also filled with the resin layer. The resin layer is tightly attached to the inner wall of the insulating drill holes.

3. The structure for increasing PCB current flow at low cost according to claim 2, characterized in that, include: The prepreg is also disposed between the ordinary thick copper core board and the copper surface of the PCB. The first thick copper core board and the adjacent prepreg are bonded together using a low-adhesion prepreg or a thin prepreg. The surface of the ordinary thick copper core board is etched with a circuit layer, and both the surface of the first thick copper core board and the ordinary thick copper core board are provided with a browning layer.

4. A low-cost design method for increasing PCB current carrying capacity, characterized in that, The structure for increasing PCB current carrying capacity at low cost according to claim 3 includes the following steps: Step 1: Prepare and obtain the first thick copper core board, ordinary thick copper core board, prepreg and PCB surface copper with matching specifications respectively; Step 2: Process the copper foil on both sides of the first thick copper core board to form the first line groove and retain the residual copper layer at the bottom; Step 3: Use an etching process to remove the residual copper layer, so that the first line groove forms the second line groove; Step 4: The second line groove and the insulating drill hole are filled with resin. After curing and polishing, a browning layer is formed on the surface of the first thick copper core board. Step 5: Perform circuit etching on the ordinary copper thick core board, and form a brown layer on its surface after completion; Step 6: The first thick copper core board after browning, the ordinary thick copper core board, the prepreg, and the PCB copper are sequentially stacked and pressed together to form the first circuit board. Step 7: Perform subsequent molding processing on the first circuit board to obtain a target PCB circuit board with high current carrying capacity.

5. A low-cost design method for increasing PCB current carrying capacity according to claim 4, characterized in that, In step 2, before processing the first line groove, positioning holes and reference points are first opened on the edge of the first thick copper core board. The first thick copper core board is fixed on the worktable of the processing equipment by a fixture. The warpage of the first thick copper core board is ≤1mil. Then, the first line groove is processed by laser engraving or milling machine precision engraving. After processing one side of the copper foil, the first thick copper core board is flipped over and re-fixed. The same specification first line groove is processed on the other side of the copper foil.

6. The low-cost design method for increasing PCB current carrying capacity according to claim 4, characterized in that, In step 3, the residual copper layer is removed by selecting either an acid etching process or an alkaline etching process based on the depth and width of the second line groove.

7. The low-cost design method for increasing PCB current carrying capacity according to claim 4, characterized in that, In step 4, resin ink is pressed into the second line groove and insulating drill hole by a scraper. The angle, speed and pressure of the scraper are adjusted to remove air bubbles. First, ultraviolet light is used for segmented irradiation combined with stepped heating for pre-curing. Then, sanding belt or non-woven cloth abrasive is used to remove the resin overflowing from the board surface, so that the resin layer is flush with the surface of the first thick copper core board. Finally, the first thick copper core board is subjected to browning treatment to form a browning layer.

8. A low-cost design method for increasing PCB current carrying capacity according to claim 4, characterized in that, In step 6, the first thick copper core board after browning, the ordinary thick copper core board, the prepreg, and the PCB copper are stacked sequentially according to the layer design requirements, and the pressing process is used to make each layer tightly bonded to form an integrated first circuit board.

9. A low-cost design method for increasing PCB current carrying capacity according to claim 4, characterized in that, In step 7, the subsequent forming process includes drilling, electroplating, circuit forming, solder resist, surface treatment and shape forming in sequence. The surface of the target PCB circuit board after forming is coated with a green solder mask layer, and the through holes on the circuit board are provided with a green solder mask plugging structure.

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