A method for manufacturing a remote radio unit line board

Abstract

The application relates to a remote machine radio frequency pull-out unit circuit board manufacturing method, which sets a buried copper block reserved space through an inner layer process, processes through a laminated riveting and heat capacity pressing step to fix and adhere each double-sided copper-clad plate and a PP layer, a buried copper block and a riveted circuit board together, then carries out outer layer pattern setting on the adhered circuit board through an outer layer process, carries out grinding, electroplating, drilling, hole plugging and depth control milling groove processing on the surface, carries out copper plating on the copper-lacking and recessed positions, guarantees that the surface copper thickness meets the standard requirements, and finally completes the manufacturing through a post-process. The remote machine radio frequency pull-out unit circuit board manufacturing method has the advantages of high stability, good conductive performance, long service life and high circuit precision.

Description

Technical Field

[0001] This invention relates to the field of radio frequency circuit board manufacturing, specifically a method for manufacturing a remote radio frequency remote unit circuit board. Background Technology

[0002] Radio frequency (RF) remote units are divided into near-end units (wireless baseband control) and far-end units (RF remote units). Generally, in PCB circuit boards, RF circuit boards are any high-frequency PCBs operating above 100MHz, used for communication signals in any application that needs to receive and transmit wireless signals. However, the manufacturing difficulty of RF circuit boards is higher than that of traditional PCB boards. This far-end RF remote unit circuit board is a printed circuit board with multiple complex processes including embedded copper blocks, controlled-depth drilling, controlled-depth milling, resin plugging, and capping electroplating. Therefore, the manufacturing process and control points are very different from those of traditional ordinary circuit boards, and several problems will also arise. Among them, the problems of conductive connection between the embedded copper block and the PCB board, edge wear and exposed substrate, and removal of copper wires in the controlled-depth drilled holes have not been solved. Summary of the Invention

[0003] The purpose of this invention is to provide a method for manufacturing a remote radio frequency remote unit circuit board that is highly stable, has good conductivity, high circuit accuracy, and is durable and corrosion resistant.

[0004] To achieve the above objectives, the following technical solutions are employed.

[0005] A method for manufacturing a remote radio frequency remote unit circuit board includes the following steps: S1: Fabrication of inner layer circuits, PP layer and embedded copper blocks for each double-sided copper clad laminate. After the inner layer circuits of double-sided copper clad laminates of layers L(n-3) to Ln are fabricated, a forming process is added to the PP and double-sided copper clad laminates of layers L(n-3) to Ln respectively. The forming process is to open a window at the position corresponding to the preset embedded copper block of the double-sided copper clad laminates of layers L(n-3) to Ln. The thickness of the embedded copper block is greater than the bonding thickness of the double-sided copper clad laminates of layers L(n-3) to Ln, where n is an even number greater than or equal to 6. S2: Layer stacking and riveting process: After stacking and hot-melting the double-sided copper-clad boards and PP layers prepared in step S1, they are riveted together to obtain multiple n-layer unit circuit boards from L1 to Ln. S3: Pressing process, including... S3.1: Place the embedded copper block. Place the prepared embedded copper block into the windowed embedded copper position on the n-layer unit circuit board. S3.2: Pre-stack the multiple n-layer unit circuit boards obtained in step S2 in a tray. Each tray contains two n-layer unit circuit boards per layer, for a total of m layers of n-layer unit circuit boards. The bottom n-layer unit circuit board has a lower buffer layer on its bottom surface, and the top n-layer unit circuit board has an upper buffer layer on its top surface. An intermediate buffer layer is provided between adjacent n-layer unit circuit boards in the middle layer. The upper buffer layer and the lower buffer layer have the same thickness, and the upper buffer layer is greater than the thickness of the intermediate buffer layer. Here, m is a natural number greater than 1. S3.3: After pre-stacking is completed, the boards are placed in a press machine to perform synchronous pressing of multiple n-layer unit circuit boards, resulting in multiple pressed n-layer unit circuit boards. S4: Outer layer processing; S5: The subsequent process completes production.

[0006] In the above scheme, the method for manufacturing a remote radio frequency remote unit circuit board involves setting up copper embedding positions in the inner layer process of the preceding process. Each double-sided copper-clad laminate and PP layer are fixed by a hot-melt riveting process to obtain an n-layer unit circuit board. Then, the copper embedding block is placed in the aforementioned reserved position and the entire board is pressed together. The pressed n-layer unit circuit board is then processed through outer layer processes and subsequent processes to produce the required circuit board. Furthermore, in step S1, a molding process is added to the L(n-3) to Ln layers of double-sided copper-clad laminate and PP layer, and a windowing process is applied to the L(n-3) to Ln layers of double-sided copper-clad laminate and PP layer to reserve space for the copper embedding block. To effectively prevent the copper block from sinking, this process is further improved. To prevent subsequent multiple grinding processes from causing connection problems between the n-layer unit circuit board and the substrate, the thickness of the embedded copper block needs to be 0.05mm-0.1mm greater than the lamination thickness at the location of the embedded copper block. In step S2 above, to prevent the PP layers to be laminated from mixing with other PP materials, the workbench surface is cleaned from cutting to lamination of the PP layers, thereby protecting the surface cleanliness of the board after hot-melt lamination. Dragging the hot-melt unit circuit board is prohibited during the lamination process to ensure the smooth operation of subsequent lamination processes. In the lamination process of step S3 above, to strengthen the bonding force between the embedded copper block and the n-layer board and enhance the stability of the inner layers of the circuit board, the material is placed before step S3.1... The embedded copper block and the core board in the double-sided copper-clad laminate are browned to prevent delamination and board bursting during lamination. Then, pre-stacking is performed. Before pre-stacking, a suitable tray is selected, and the unit circuit boards to be laminated are arranged side-by-side within the tray. To prevent damage to the inner layers due to excessive pressure during mechanical lamination, buffer layers are set between the bottommost unit circuit boards, between adjacent unit circuit boards, and on the upper surface of the topmost unit circuit board during the pre-stacking process. The upper and lower buffer layers are larger than the middle buffer layer. These buffer layers prevent damage to the unit circuit boards during lamination and extend their service life. After lamination, the laminated unit circuit boards are further... The board undergoes outer layer processing and post-processing. The post-processing includes pulse electroplating, blind milling, etching, inspection, and packaging. The pulse electroplating process ensures that the copper thickness inside the holes and on the board surface meets the requirements, thereby enhancing the durability and corrosion resistance of the unit circuit board. The blind milling process uses controlled depth milling to blindly extract the copper embedding blocks, resulting in a stepped edge for the slots at the copper embedding blocks, thus stabilizing the overall structure of the unit circuit board. The etching process uses an alkaline solution. The inspection process includes electrical testing, FQC (Final Quality Control), and OQC (Outgoing Quality Control) to ensure that the manufactured n-layer unit circuit board meets product specifications.

[0007] Furthermore, in step S3.2 above, before pre-stacking, an ordinary aluminum sheet is placed on the copper foil on the side of each n-layer unit circuit board located on the buried copper block.

[0008] In the above scheme, in order to prevent the copper foil on the copper block from being damaged due to excessive pressure during the lamination process, before the lamination process, a layer of ordinary aluminum sheet is placed on the copper foil of the copper block as a buffer sheet for each unit circuit board. It has the advantages of low manufacturing cost, light weight and good conductivity, which can ensure that the conductivity of the unit circuit board is not affected.

[0009] Furthermore, the outer layer process in step S4 includes a grinding process, an electroplating process, a drilling process, a hole plugging process, and a depth-controlled milling process. The grinding process is performed in five steps, with the first grinding process being the process after the pressing treatment. The electroplating process includes a plate electroplating process and a pattern electroplating process. The drilling process includes a mechanical drilling process and a depth-controlled drilling process. The hole plugging process is the process after the depth-controlled drilling process.

[0010] In the above scheme, to ensure the precision and performance of the outer layer of the circuit board, the outer layer process includes five main processes: grinding, electroplating, drilling, hole plugging, and controlled-depth milling. The grinding process is mainly used to grind away excess metal layers on the circuit board surface. Specifically, in this invention, the grinding process is performed in five stages, grinding the circuit board after the lamination, electroplating, drilling, and hole plugging processes respectively, to ensure that the dimensional accuracy and surface roughness of the circuit board meet the requirements, thus improving the precision of the outer layer circuitry. The first grinding process removes lamination residue and copper foil from the copper blocks, smoothing the circuit board surface and ensuring that the circuit board dimensions meet the design dimensions, thereby providing good surface quality and enhancing the stability of the circuit board. The electroplating process mainly... After grinding, copper plating is applied to areas with insufficient copper or depressions on the surface of the circuit board to thicken the surface copper to meet standard requirements. The drilling process involves drilling holes of different diameters or depths on the outer layer of the circuit board. The hole-filling process fills the holes drilled in the previous drilling process to prevent chemical residues from remaining in the holes during circuit board manufacturing, which could affect signal transmission and reduce conductivity. The controlled-depth milling process involves creating grooves from the outer layer of the board to the inner layer during the outer layer process. This process helps to fix the circuit board during installation, saving space without reducing the amount of board material, and also makes the connection between the circuit board and the equipment more stable. In the pulse electroplating process in step S5 above, low-current, long-time electroplating copper is used to reduce hole protrusion and improve the aesthetics and precision of the outer layer circuitry. The electroplated copper thickness is 0.5-0.7 mil.

[0011] Furthermore, the grinding process is divided into a first grinding and a second grinding. The first grinding passes through the abrasive belt section, the ceramic section, and the non-woven fabric section, with the board feeding direction being the long side of the embedded copper block. The second grinding only passes through the non-woven fabric section, with the board feeding direction depending on whether the residual adhesive is on the long or short side of the embedded copper block. The residual adhesive is the abrasive belt or ceramic slag remaining from the first grinding.

[0012] In the above solution, the grinding process is carried out using a grinding machine, which has three grinding sections: a sanding belt section, a ceramic section, and a non-woven fabric section. The sanding belt section uses sandpaper or abrasive cloth as the grinding material, which has the advantages of high polishing precision and low grinding cost. The ceramic section uses smooth ceramic as the grinding material, which has the characteristics of high temperature resistance, wear resistance, and high hardness. The non-woven fabric section uses non-woven fabric as the grinding material, which can protect the circuit board from blackening and the workpiece dimensions from changing during the grinding process, and has the advantages of durability and high surface finish. In the above technical solution, the grinding process is divided into three sections. The process is carried out in two stages. Specifically, the first grinding stage involves three grinding sections to uniformly remove a very thin layer of metal from the surface of the circuit board. To ensure that the copper thickness on the circuit board surface meets the preset requirements, the second grinding stage only involves a non-woven fabric section. This process removes any residual sand or ceramic residue from the surface of the circuit board after the first grinding stage, preventing it from damaging the outer layer of the unit circuit board in subsequent processes, reducing its durability, and thus its stability. It also ensures the cleanliness of the circuit board surface and improves the precision of the outer layer of the circuit board.

[0013] Furthermore, the plate electroplating process includes a first plate electroplating process and a second plate electroplating process. The first plate electroplating process is a process following the first grinding process, and the second plate electroplating process is a process following the fourth grinding process. The fourth grinding process is a process following the mechanical drilling process. The second plate electroplating process uses a low current density and involves long-term electroplating.

[0014] In the above scheme, to protect the non-conductive substrate of the drilled hole walls, a layer of PTH board needs to be chemically deposited on the surface of the circuit board before the board electroplating process. The PTH is chemical copper, which also serves as the matrix for subsequent copper plating. In the shaping process, the board electroplating process is performed in two steps. Specifically, the first board electroplating process is to plate copper on the copper-deficient parts of the substrate at the edge of the embedded copper block after the first grinding process and on the entire board surface. To protect the chemical copper layer, the copper plating thickness is controlled at 5µm-10µm to prevent the chemical copper layer from being corroded away in the next process. A plasma desmearing process is also added before the second board electroplating process. The first step is to remove residual adhesive from the hole walls after mechanical drilling, improve the activity inside the hole, and thus improve the conductivity of the unit circuit board. The second electroplating process has a copper thickness of 0.4-0.7 mil. To reduce the protrusion of the hole opening after mechanical drilling, the second electroplating process uses a low current and long time electroplating method to ensure the accuracy and fineness of the outer layer circuit of the unit circuit board. The fourth grinding process is a post-mechanical drilling process. On the one hand, it can smooth the uneven hole walls after drilling, and on the other hand, it can remove the debris left on the hole wall surface during drilling, thereby ensuring that the conductivity of the circuit board is not affected.

[0015] Furthermore, the patterning process includes an outer patterning process, a pattern electroplating process, and a stripping process. The patterning process includes a first patterning process and a second patterning process. The first patterning process is a process before the second grinding process, and the second grinding process is a process after the first board electroplating process. The first patterning process involves copper plating on the embedded copper block and its surrounding area. The second patterning process is a process after the second board electroplating process, and the second patterning process involves copper plating at the copper block position on the Ln surface of the board.

[0016] In the above scheme, the patterning process involves an outer patterning process that coats the circuit board surface with a thin film, followed by pattern development, and then a pattern electroplating process to thicken the copper thickness of the circuits and holes. The process is then completed by removing the film. The patterning process is performed in two steps. Specifically, the first patterning process involves copper plating on the embedded copper block location and its 0.5mm width perimeter, with a copper plating thickness of 10µm-20µm. To compensate for the copper layer removed in the third grinding process, the second grinding process is performed after the first patterning process. This process removes the tiny protrusions formed on the surface after copper plating, ensuring that the copper thickness on the circuit board surface meets design requirements and maintains good smoothness, thereby improving the board's bonding performance. The second patterning process also involves copper plating on the Ln side of the board, with a copper plating thickness of 1.2mil. This ensures that the copper thickness on the substrate at the edge of the embedded copper block meets requirements and does not affect the overall circuit fabrication. It also ensures the conductivity of the unit circuit board, enhances its surface corrosion resistance, and extends its service life.

[0017] Furthermore, the mechanical drilling process is a process following the third grinding process, which is a process following the first drawing process. The mechanical drilling process takes the L1 side of the board as the forward drilling direction and is divided into two drilling operations. The first drilling simultaneously drills two through holes, namely the first through hole and the second through hole. The second drilling drills a third through hole. The diameter of the first drilling is larger than that of the second drilling, and the first through hole, the second through hole, and the third through hole are distributed at equal distances from each other and move sequentially toward the embedded copper block.

[0018] In the above scheme, the third grinding process smooths and polishes the copper surface thickened in the first drawing process, ensuring the surface copper thickness meets design requirements and enhancing the surface accuracy of the circuit board. The mechanical drilling process uses L-shaped target holes for positioning along the board edge. These L-shaped target holes fit snugly against the edge of the n-layer board, facilitating clamping. Before drilling, two cover plates are placed on the upper surface of the n-layer unit circuit board to be processed, serving to fix the drill bit, protect the board surface, and improve hole position accuracy. To prevent direct contact between the drill bit and the drilling machine table during through-hole drilling, the n-layer unit circuit board is... A pad is placed on the lower surface of the unit circuit board to guide and fix the drill bit, thereby improving the hole position accuracy and thus improving the accuracy of the unit circuit board. The mechanical drilling process starts from the non-copper surface and uses different types of drill bits to drill twice. The diameter of the first drill hole is larger than that of the second drill hole. The first drilled hole is the first through hole and the second through hole. The second drilled hole is the third through hole. The distance between the centers of each pair of through holes is the same. The third through hole is located on the right side of the embedded copper block and is closest to the embedded copper block.

[0019] Furthermore, the controlled-depth drilling process is a process following the second drawing and electrical process. The controlled-depth drilling process uses the Ln surface of the plate as the forward drilling direction. The controlled-depth drilling process involves drilling only once. The hole drilled by the controlled-depth drilling process is a back-drilled hole. The diameter of the back-drilled hole is larger than the diameter of the first through hole. The back-drilled hole and the third through hole are concentrically distributed.

[0020] In the above scheme, to facilitate the removal of copper wires inside the back-drilled holes in subsequent processes, the entire board is first tin-plated, followed by controlled-depth drilling. The controlled-depth drilling process drills from the copper block surface between layers Ln to Ln-4 of the board. The back-drilled holes are concentric with the third through-hole, and the diameter of the back-drilled holes is larger than that of the first through-hole. After the controlled-depth drilling process is completed, the copper wires inside the back-drilled holes are removed by etching. To completely remove the copper wires inside the holes, an alkaline solution is used for etching. The etching depth can be controlled by controlling the concentration of the alkaline solution, thereby removing copper wires located deep inside the holes. It also has the advantages of high speed and high copper dissolution capacity, and can remove all residual copper wires inside the back-drilled holes, preventing residual copper wires from clogging the holes and affecting the working performance of the unit circuit board.

[0021] Furthermore, the hole-plugging process uses resin material to plug the second through hole and the back-drilled hole respectively, and then performs copper plating and hole-capping electroplating processes on the second through hole.

[0022] In the above scheme, the via plugging process uses resin material to fill the holes to ensure the stability and reliability of the circuit board. Since the diameters of the second through hole and the back-drilled hole that need to be plugged are different, in order to prevent uneven or incomplete plugging, the resin plugging process is performed separately for holes of different diameters. Then, the second through hole is subjected to copper plating and cover plated processes. A copper layer is applied to the exposed substrate area of ​​the resin plugged hole to meet the customer's design requirements. The copper thickness of the cover plated hole is 0.3-0.4 mil.

[0023] Furthermore, the controlled depth milling process is a process following the fifth grinding process, and the fifth grinding process is a process following the hole plugging process. The controlled depth milling process mills grooves between layers Ln and L(n-1) of the embedded copper block to obtain grooves. The width of the grooves is smaller than the width of the embedded copper block. The controlled depth milling uses a CCD milling machine. A white pad is provided between the CCD milling machine and the n-layer board. The white pad has grooves.

[0024] In the above scheme, the fifth grinding process is a pre-process of the controlled-depth milling process. It grinds off the excess resin on the surface of the circuit board after the hole is plugged to ensure surface flatness and not affect the overall aesthetics of the circuit board. Since the copper block is embedded in the circuit board, the circuits of the adjacent inner layers cannot be seen from the outermost layer of the board. Therefore, the controlled-depth milling performs blind milling at the opening position of the copper block, which can increase the utilization of the inner layer circuit space of the unit circuit board and can also be used for the connection between the outer layer circuits and the inner layer circuits, thereby strengthening the information conductivity and improving the conductivity of the unit circuit board. The blind milling is achieved by a CCD milling machine. The CCD milling machine is a CNC program milling machine, which has the advantages of high processing accuracy and the ability to accurately identify the milling position. The milling surface of the CCD milling machine uses a white pad to place the n-layer board. The surface of the white pad is smooth and clean to avoid damage to the outer layer circuits of the board during milling. For the white pad, in order to make the white pad adhere flatly to the CCD milling machine table, the white pad is slotted and vacuum adsorbed onto the table.

[0025] Compared with the prior art, the method for manufacturing the remote radio frequency remote unit circuit board of the present invention has the following advantages: First, it has strong stability. In the inner layer process, a space is reserved for the embedded copper block to fit. Then, each double-sided copper clad board is riveted to the PP layer to strengthen the stability between adjacent double-sided copper clad boards. Then, the adhesion between the two is increased by hot melt pressing, so that the embedded copper block and the unit circuit board are firmly attached together. Secondly, it has good conductivity. The outer layer process solves the problems of poor conductivity between the copper block and the substrate and copper leakage on the surface, thereby ensuring the copper thickness on the circuit board surface and improving the conductivity of the circuit board. Third, it has a long service life. By setting process operation parameters in the outer layer process of the circuit board, selecting specified materials for the process, and adding a buffer layer between the top layer of the top circuit board, the bottom layer of the bottom circuit board, and adjacent circuit boards during the lamination and pre-stacking process, the inner layer circuits of the circuit board are protected, thereby extending the service life. Attached Figure Description

[0026] Figure 1 This is a layer diagram of a 6-layer unit circuit board for a method of manufacturing a remote radio frequency remote unit circuit board according to the present invention. Figure 2 This is a cross-sectional view of a 6-layer unit circuit board for a remote radio frequency remote unit circuit board manufacturing method of the present invention; Figure 3 This is a layout diagram of a 6-layer unit circuit board for a method of manufacturing a remote radio frequency remote unit circuit board according to the present invention; Figure 4 This is an 8-layer unit circuit board stack-up diagram of a method for manufacturing a remote radio frequency remote unit circuit board according to the present invention; Figure 5 This is a cross-sectional view of an 8-layer board unit circuit of a method for manufacturing a remote radio frequency remote unit circuit board according to the present invention. Figure 6 This is an 8-layer board unit circuit stack diagram of the method for manufacturing a remote radio frequency remote unit circuit board of the present invention; Figure 7 This is a 10-layer board unit circuit layer diagram of a method for manufacturing a remote radio frequency remote unit circuit board according to the present invention; Figure 8 This is a cross-sectional view of a 10-layer board unit circuit of a remote unit radio frequency remote unit circuit board manufacturing method of the present invention; Figure 9 This is a 10-layer board unit circuit stack diagram of a method for manufacturing a remote radio frequency remote unit circuit board according to the present invention.

[0027] Explanation of reference numerals in the attached figures: 6-layer unit circuit board 1A, 8-layer unit circuit board 1B, 10-layer unit circuit board 1C, double-sided copper clad board 1D, embedded copper block 20, buffer board 30, buffer pad 4040, first through hole 50, second through hole 60, third through hole 70, back drill hole 80, ordinary aluminum sheet 90. Detailed Implementation

[0028] The following will describe in further detail a method for manufacturing a remote radio frequency remote unit circuit board according to the present invention, with reference to specific embodiments and accompanying drawings.

[0029] This invention provides a non-limiting example of a method for manufacturing a remote radio frequency (RF) remote unit circuit board, specifically including: embedded copper block 20 → PP → inner layer → lamination → grinding → PTH + board electroplating → grinding → lamination and target bonding → outer layer pattern (positive film) → pattern electroplating (without tin) → film removal → grinding → lamination and target bonding → drilling → grinding → plasma adhesive removal → PTH + board electroplating → outer layer pattern (positive film) → pattern electroplating (without tin) → mechanical depth-controlled back drilling → alkaline etching → resin hole plugging → grinding → lamination and target bonding → hot pressing → depth-controlled milling → immersion copper + CAP electroplating → outer layer circuitry → circuit etching (positive film) → pulse pattern electroplating → blind milling → etching → solder mask → electroless gold plating → text → forming → electrical testing → FQC / OSP → OQC → Packaging, in which, after the inner layer circuit is made, a forming process is added to each double-sided copper clad board 1D from Ln to L(n-3) to perform inner layer windowing treatment; after the PP layer is cut, windowing treatment is also performed, and the size of the windowing treatment is adapted to the size of the embedded copper block 20; the completed PP and double-sided copper clad board 1D are stacked and riveted in sequence, waiting for subsequent pressing. Example 1

[0030] Reference Figures 1 to 3 This invention provides a non-limiting example of a method for fabricating a remote radio frequency (RF) remote unit circuit board. This embodiment uses a 6-layer unit circuit board as an example for illustration, and includes the following steps. S1: Fabrication of the inner layer circuitry, PP layer, and embedded copper block 20 of each double-sided copper clad laminate 1D. Specifically, first, PP material is cut, and the inner layer circuitry of the two double-sided copper clad laminates 1D of layers L3 to L6 is fabricated. Then, a molding process is added to the PP and the double-sided copper clad laminates 1D of layers L3 to L6. The molding process involves opening windows at the positions of the PP and the double-sided copper clad laminates 1D of layers L3 to L6 corresponding to the preset embedded copper block 20. The thickness of the embedded copper block 20 is greater than the bonding thickness of the PP and the double-sided copper clad laminates 1D of layers L3 to L6. Specifically, in this embodiment, the thickness of the embedded copper block 20 is 0.05mm to 0.1mm greater than the bonding thickness at the position of the embedded copper block 20. S2: Layer stacking and riveting process: After stacking and hot-melting the double-sided copper clad boards 1D made in step S1 with the PP layer, they are riveted together to obtain multiple 6-layer unit circuit boards 1A from L1 to L6. S3: Pressing process, including... S3.1: Place the copper embedding block 20. Place the prepared copper embedding block 20 into the open copper embedding position on the 6-layer unit circuit board 1A. S3.2: Pre-stack the multiple 6-layer unit circuit boards 1A obtained in step S2 in a tray. Two 6-layer unit circuit boards 1A are arranged in each layer in each tray, for a total of 4 layers of 6-layer unit circuit boards 1A. The bottom layer of the unit circuit board has a lower buffer layer on its bottom surface, and the top layer of the unit circuit board has an upper buffer layer on its top surface. An intermediate buffer layer is provided between adjacent unit circuit boards in the middle layer. The upper buffer layer and the lower buffer layer have the same thickness, but the upper buffer layer has a greater thickness than the intermediate buffer layer. S3.3: After pre-stacking is completed, the multiple unit circuit boards are put into the press equipment for synchronous pressing to obtain multiple pressed 6-layer unit circuit boards 1A; S4: Outer layer processing; S5: The subsequent process completes production.

[0031] In step S1 above, the embedded copper block 20, PP layer, and each double-sided copper clad laminate 1D are fabricated separately. After the PP layer is cut and the inner layers of the double-sided copper clad laminate 1D are fabricated, the PP layer and each double-sided copper clad laminate 1D of layers L3 to L6 are windowed to reserve space for the embedded copper block 20. The thickness of the embedded copper block 20 is set to be greater than the lamination thickness of layers L3 to L6, which can effectively prevent the copper block from sinking, thereby solving the problem of poor substrate connection caused by the copper block sinking. In step S2 above, after the embedded copper block 20, PP layer, and each double-sided copper clad laminate 1D are fabricated, the double-sided copper clad laminate 1D and PP layer are laminated and riveted. In this embodiment, in order to enhance the stability after riveting and to avoid interlayer errors in subsequent work and lamination process, To prevent layer misalignment, eight rivets are used for riveting and fixing to obtain a 6-layer unit circuit board to be pressed. To prevent the PP layers to be stacked from mixing with other PP materials, the workbench surface is cleaned from cutting to stacking the PP layers, thus protecting the surface cleanliness of the board after subsequent hot-melt stacking. Dragging the unit circuit board is prohibited during the stacking process to ensure the subsequent pressing process. In step S3 above, during the pressing process, the embedded copper block 20 is first placed at the windowed embedded copper position on the unit circuit board to be pressed. Specifically, to strengthen the bonding force between the embedded copper block 20 and the 6-layer unit circuit board 1A, the core board in the embedded copper block 20 and the double-sided copper-clad laminate 1D is browned before placement in step S3.1, thereby avoiding delamination and board bursting during pressing. Then, pre-processing is performed. Before pre-stacking, a suitable tray is selected, and the unit circuit boards to be pressed are arranged side-by-side in the tray. In this embodiment, two rows are arranged side-by-side in the tray, with 4 layers pre-stacking in each row, which is equivalent to 8 unit circuit boards per tray. To prevent damage to the inner layers due to excessive pressure during mechanical pressing, buffer layers are set between the bottom unit circuit boards, between adjacent unit circuit boards, and on the upper surface of the top unit circuit board during the pre-stacking process. The upper and lower buffer layers are larger than the middle buffer layer. In this embodiment, the buffer material of the buffer layers is all new kraft paper. Kraft paper has good tensile strength and low cost, and new kraft paper can also prevent the inner layers from being damaged by old and broken kraft paper during pressing. After adopting this pre-stacking scheme, then... The lamination process effectively improves the lamination efficiency and, with the buffer layer, provides excellent protection for the unit circuit board. After lamination, the 6-layer unit circuit board undergoes outer layer processing and post-processing. The post-processing includes blind milling, etching, inspection, and packaging. The blind milling process involves blindly milling the embedded copper block 20 to create a stepped edge on the slot of the embedded copper block 20. The etching process uses an alkaline solution. The inspection process includes electrical testing, FQC, and OQC finished product quality inspection to ensure that the manufactured 6-layer unit circuit board 1A meets product specifications, thereby producing the required circuit board.Specifically, in this embodiment, in step S3.1 above, the copper block browning is performed using different parameters depending on the thickness of the embedded copper block 20. To avoid poor connection between the copper block and the substrate, the thickness of the embedded copper block 20 is 0.05mm-0.1mm greater than the pressing thickness at the embedded copper block 20 position. Within this range, the browning speed of the embedded copper block 20 is 2m / min, and the baking temperature and time after browning are 120°C and 30min, respectively. The browning speed of the double-sided copper-clad laminate 1D is 3.5m / min, and the baking parameters are 120°C*60min. Furthermore, to ensure the connection between the copper block and the PP layer during hot-melt lamination... The contact area is brown; in this example, the fusion temperature is 300°C and the fusion time is 45s; during the pre-stacking process, each tray is pre-stacked with 4 layers. Due to the excessive pressure of mechanical stacking, the inner circuit board is damaged. Specifically, 20 sheets of brand new kraft paper are used as buffer boards 30 on the top and bottom layers of the 6-layer unit circuit board. Since the pressure on the inner layer is less than that on the outer layer, 5 sheets of brand new kraft paper are used as buffer pads 40 between adjacent unit circuit boards. These pads can fill the pressure loss caused by the copper thickness being higher than the lamination thickness, preventing the unit circuit board from deforming or being damaged during the lamination process.

[0032] Reference Figures 1 to 3 In a non-limiting embodiment of the present invention, in step S3.2 above, before pre-stacking, an ordinary aluminum sheet 90 is placed on the copper foil on the side of the embedded copper block 20 of each of the six-layer unit circuit boards. In the above scheme, in order to prevent damage to the copper foil on the copper block due to excessive pressure during the lamination process, specifically, before the lamination process, after each layer of unit circuit boards is placed, an ordinary aluminum sheet 90 is placed on the unit circuit board as a buffer, and then a buffer layer is placed on the ordinary aluminum sheet 90. That is, an ordinary aluminum sheet 90 is added between the unit circuit board and the buffer layer for buffering. The ordinary aluminum sheet 90 has the advantages of low manufacturing cost, light weight, and good conductivity, thereby ensuring that the conductivity of the unit circuit board is not affected.

[0033] Reference Figure 1In a non-limiting embodiment of the present invention, the grinding process is divided into a first grinding and a second grinding. The first grinding passes through the abrasive belt section, the ceramic section, and the non-woven fabric section, with the board feeding direction along the long side of the embedded copper block 20. The second grinding only passes through the non-woven fabric section, with the board feeding direction depending on whether the residual adhesive is on the long or short side of the embedded copper block 20. The residual adhesive is the abrasive belt or ceramic slag remaining from the first grinding. The grinding process is carried out by a grinding machine, which is divided into three grinding sections: the abrasive belt section, the ceramic section, and the non-woven fabric section. The abrasive material in the abrasive belt section is sandpaper or abrasive cloth, which has... The polishing process offers advantages such as high precision and low grinding cost. The ceramic section uses smooth ceramic as its grinding material, which is characterized by high temperature resistance, wear resistance, and high hardness. The non-woven fabric section uses non-woven cloth as its grinding material, which protects the circuit board from blackening and maintains its dimensions during grinding, while also offering durability and high surface finish. In the above technical solution, the grinding process is performed in two passes. Specifically, the first pass involves three grinding stages, which uniformly removes a very thin layer of metal from the circuit board surface. This ensures that the copper thickness on the circuit board surface meets the preset requirements. The second polishing pass only involves the non-woven fabric section. This serves two purposes: firstly, it removes any residual abrasive or ceramic slag from the circuit board surface after the first polishing process, preventing these residues from damaging the outer layers of the unit circuit board in subsequent processes, thus reducing its durability and stability; secondly, it ensures the cleanliness of the circuit board surface and improves the precision of the outer layers. In this embodiment, taking a 6-layer unit circuit board 1A as an example, the current intensity is the pressure applied to the board surface during polishing. Since the laminated copper foil is relatively thin, excessive pressure will damage the copper foil on the board surface. Therefore, in the grinding process, the current passing through the abrasive belt section and the ceramic section is 2.0A. Since the grinding material of the non-woven section is non-woven fabric, it is softer than the abrasive belt and ceramic, and the pressure on the board surface can be reduced. Therefore, the current intensity passing through the non-woven section is higher than the current intensity passing through the abrasive belt section and the ceramic section, and the current is 2.5A. In order to avoid excessive pressure on the edge of the embedded copper block 20 due to grinding, which would cause excessive wear of the copper layer on the substrate in this area and expose the substrate, the angle at which the 6-layer unit circuit board 1A is placed into the grinding machine is 30° during the grinding process.

[0034] Reference Figure 1In a non-limiting embodiment of the present invention, the mechanical drilling process is a process following the third grinding process, which is a process following the first electroplating process. The mechanical drilling process is performed with the L1 side of the board as the forward direction. The mechanical drilling process is divided into two drilling operations. The first drilling simultaneously drills two through holes, namely the first through hole 50 and the second through hole 60. The second drilling drills a third through hole 70. The diameter of the first drilling is larger than that of the second drilling, and the first through hole 50, the second through hole 60, and the third through hole 70 are distributed at equal distances from each other and are sequentially directed towards the embedded copper block 20. In this embodiment, the third grinding process smooths and polishes the copper surface thickened by the first drawing process, ensuring the surface copper thickness meets design requirements and enhancing the surface precision of the circuit board. The mechanical drilling process uses L-shaped target holes for positioning along the board edge. These L-shaped target holes fit precisely with the edge of the 6-layer unit circuit board 1A, facilitating clamping. Before drilling, two cover plates are placed on the upper surface of the 6-layer unit circuit board 1A to fix the drill bit, protect the board surface, and improve hole position accuracy. To prevent direct contact between the drill bit and the drilling machine table during through-hole drilling, a pad is placed on the lower surface of the 6-layer unit circuit board 1A. The board can also guide and fix the drill bit, thereby improving the hole position accuracy; the mechanical drilling process drills from the non-copper surface, thereby improving the accuracy of the circuit board. The mechanical drilling process uses different types of drill bits to perform two drilling operations. The diameter of the first drilling hole is larger than that of the second drilling hole. The first drilled hole is the first through hole 50 and the second through hole 60. The second drilled hole is the third through hole 70. The distance between the centers of each pair of through holes is the same. The third through hole 70 is located on the right side of the embedded copper block 20 and is closest to the embedded copper block 20. In this embodiment, taking a 6-layer unit circuit board 1A as an example, the first drilling... The first hole is drilled using a conventional drill bit with a diameter of 3.7 mm. The second hole is drilled using a 0.9 mm drill bit with a diameter of 0.9 mm. The cover plate is covered with a coated aluminum sheet, and when the cover plate is placed on the upper surface of the 6-layer unit circuit board 1A, the aluminum sheet faces upwards. It has the advantages of corrosion resistance and good hardness, which can prevent the cover plate from being damaged during drilling and protect the circuit board. The pad placed on the lower surface of the board is a white pad with a moderate density of intermediate fiber layer, which can reduce wear on the drill bit and extend the drill bit life. At the same time, the material is uniform, not easy to deform, and has good chip removal, which can reduce cutting heat and reduce needle breakage.

[0035] Reference Figure 1In a non-limiting embodiment of the present invention, the controlled-depth milling process is a post-process after the fifth grinding process, and the fifth grinding process is a post-process after the hole plugging process. The controlled-depth milling process mills grooves between layers L6-L5 of the embedded copper block 20 to obtain slots. The width of the slots is smaller than the width of the embedded copper block 20. The controlled-depth milling uses a CCD router, and a white pad with slots is provided between the CCD router and the 6-layer board. The fifth grinding process is a pre-process before the controlled-depth milling process, grinding away excess resin on the surface of the circuit board after hole plugging to ensure surface flatness and not affect the overall aesthetics of the circuit board. Since the embedded copper block 20 is embedded in the circuit board, the adjacent inner layer circuits are not visible from the outermost layer. Therefore, the controlled-depth milling performs blind milling at the opening position of the embedded copper block 20, which can increase the utilization of the inner layer circuit space of the unit circuit board and can also be used for connecting outer layer circuits and inner layer circuits, thereby enhancing information conductivity. To improve the conductivity of the unit circuit board, the blind milling is achieved by a CCD milling machine. The CCD milling machine is a CNC programmable milling machine, which has the advantages of high processing accuracy and the ability to accurately identify the milling position. The 6-layer unit circuit board 1A is placed on a white pad on the milling surface of the CCD milling machine. The surface of the white pad is smooth and clean to avoid damage to the outer layer circuits of the board during milling. For the white pad, in order to make the white pad adhere flatly to the CCD milling machine table, the white pad is slotted and vacuum adsorbed onto the table. In this embodiment, taking the 6-layer unit circuit board 1A as an example, when the white pad is slotted, a film plate needs to be covered on its surface. It has high strength, smooth surface, and wear resistance, and can be used as a photosensitive mask pattern in pattern transfer. In this embodiment, it can show the direction of the slot, improve the slotting accuracy, and thus improve the accuracy of the unit circuit board. Moreover, the spacing between the milling cutter blades is less than 0.2mm of the radius of the slotted hole, and the height difference of the imprint is less than 30µm. Example 2

[0036] Reference Figures 4 to 6 This invention provides a non-limiting example of a method for manufacturing a remote radio frequency (RF) remote unit circuit board. The manufacturing method is essentially the same as in Example 1, except that this example uses an 8-layer unit circuit board 1B as an example, and includes the following steps: S1: Fabrication of the inner layer circuitry, PP layer, and embedded copper block 20 of each double-sided copper clad laminate 1D. Specifically, first, PP material is cut, and the inner layer circuitry of the two double-sided copper clad laminates 1D of layers L5 to L8 is fabricated. Then, a molding process is added to the PP and the double-sided copper clad laminates 1D of layers L5 to L8 respectively. The molding process is to perform windowing treatment on the positions of the PP and the double-sided copper clad laminates 1D of layers L5 to L8 corresponding to the preset embedded copper block 20. The thickness of the embedded copper block 20 is greater than the bonding thickness of the PP and the double-sided copper clad laminates 1D of layers L5 to L8. Specifically, in this embodiment, the thickness of the embedded copper block 20 is 0.05mm to 0.1mm greater than the bonding thickness at the position of the embedded copper block 20. S2: Layer stacking and riveting process: After stacking and hot-melting the double-sided copper clad boards 1D made in step S1 with the PP layer, they are riveted together to obtain multiple 8-layer unit circuit boards 1B from L1 to L8. S3: Pressing process, including... S3.1: Place the copper embedding block 20. Place the prepared copper embedding block 20 into the open copper embedding position on the 8-layer unit circuit board 1B. S3.2: Pre-stack the multiple 8-layer unit circuit boards 1B obtained in step S2 in a tray. Two 8-layer unit circuit boards 1B are arranged in each layer in each tray, for a total of 3 layers of 8-layer unit circuit boards 1B. The bottom layer of the unit circuit board has a lower buffer layer on its bottom surface, and the top layer of the unit circuit board has an upper buffer layer on its top surface. An intermediate buffer layer is provided between adjacent unit circuit boards in the middle layer. The upper buffer layer and the lower buffer layer have the same thickness, but the upper buffer layer is thicker than the intermediate buffer layer. S3.3: After pre-stacking is completed, the multiple unit circuit boards are put into the press equipment for synchronous pressing to obtain multiple pressed 8-layer unit circuit boards 1B; S4: Outer layer processing; S5: The subsequent process completes production.

[0037] In step S1 above, the embedded copper block 20, PP layer, and each double-sided copper clad laminate 1D are fabricated separately. After the PP layer is cut and the inner layer of the double-sided copper clad laminate 1D is fabricated, the PP layer and each double-sided copper clad laminate 1D of layers L5 to L8 are windowed to reserve space for the embedded copper block 20. The thickness of the embedded copper block 20 is set to be greater than the lamination thickness of layers L5 to L8, which can effectively prevent the copper block from sinking, thereby solving the problem of poor substrate connection caused by the copper block sinking. In step S2 above, after the embedded copper block 20, PP layer, and each double-sided copper clad laminate 1D are fabricated, the double-sided copper clad laminate 1D and PP layer are laminated and riveted. In this embodiment, in order to enhance the stability after riveting and also avoid interlayer gaps during subsequent work and lamination, Errors caused layer misalignment. Eight rivets were used for riveting and fixing to obtain an 8-layer unit circuit board 1B to be pressed. To prevent the PP layers to be stacked from mixing with other PP materials, the workbench surface was cleaned from cutting to stacking the PP layers, thus protecting the surface cleanliness of the board after subsequent hot-melt stacking. Dragging the unit circuit board was prohibited during the stacking process to ensure the smooth operation of the subsequent pressing process. In step S3 above, during the pressing process, the embedded copper block 20 was first placed at the windowed embedded copper position on the unit circuit board to be pressed. Specifically, to strengthen the bonding force between the embedded copper block 20 and the 8-layer unit circuit board 1B, the embedded copper block 20 and the core board in the double-sided copper-clad laminate 1D were browned before placement in step S3.1, thereby preventing delamination and board breakage during pressing. Following pre-stacking, a suitable tray is selected, and the unit circuit boards to be pressed are arranged side-by-side within the tray. In this embodiment, two rows are arranged side-by-side within the tray, with three layers pre-stacking in each row, equivalent to six unit circuit boards per tray. To prevent damage to the inner layers due to excessive pressure during mechanical pressing, buffer layers are set between the bottommost unit circuit boards, between adjacent unit circuit boards, and on the upper surface of the topmost unit circuit board during the pre-stacking process. The upper and lower buffer layers are larger than the middle buffer layer. In this embodiment, the buffer material for the buffer layers is all new kraft paper. Kraft paper has good tensile strength and low cost, and new kraft paper can also prevent damage to the inner layers due to old and cracked kraft paper during pressing. This pre-stacking scheme is adopted. Afterwards, a lamination process is performed, which effectively improves the lamination efficiency and, on the other hand, provides good protection for the unit circuit board through the buffer layer. After lamination, the 8-layer unit circuit board 1B undergoes outer layer processing and post-processing. The post-processing includes blind milling, etching, inspection, and packaging. The blind milling process involves blindly milling the buried copper block 20 to create a stepped edge on the slot of the buried copper block 20. The etching process uses an alkaline solution. The inspection process includes electrical testing, FQC, and OQC finished product quality inspection to ensure that the 8-layer board meets the product specifications and thus produces the required circuit board.Specifically, in this embodiment, in step S3.1 above, the copper block browning is performed using different parameters depending on the thickness of the embedded copper block 20. To avoid poor connection between the copper block and the substrate, the thickness of the embedded copper block 20 is 0.05mm-0.1mm greater than the pressing thickness at the embedded copper block 20 position. Within this range, the browning speed of the embedded copper block 20 is 2m / min, and the baking temperature and time after browning are 120°C and 30min, respectively. The browning speed of the double-sided copper-clad laminate 1D is 3.5m / min, and the baking parameters are 120°C*60min. Furthermore, to ensure the connection between the copper block and the PP layer 13 during hot-melt lamination... The contact area is brown; in this example, the fusion temperature is 300°C and the fusion time is 45s; during the pre-stacking process, each tray is pre-stacked with 3 layers. Due to the excessive pressure of mechanical stacking, the inner circuit board is damaged. Specifically, 20 sheets of brand new kraft paper are used as buffer boards 30 on the top and bottom layers of the 8-layer unit circuit board 1B. Since the pressure on the inner layer is less than that on the outer layer, 5 sheets of brand new kraft paper are used as buffer pads 40 between adjacent unit circuit boards. These pads can fill the pressure loss caused by the copper thickness being higher than the lamination thickness, and prevent the unit circuit board from deforming or being damaged during the lamination process. Example 3

[0038] Reference Figures 7 to 9 This invention provides a non-limiting example of a method for manufacturing a remote radio frequency (RF) remote unit circuit board. The manufacturing method is essentially the same as in Example 1, except that this example uses a 10-layer unit circuit board (1C) as an example for illustration, and includes the following steps: S1: Fabrication of the inner layer circuitry, PP layer, and embedded copper block 20 of each double-sided copper clad laminate 1D. Specifically, first, PP material is cut, and the inner layer circuitry of the two double-sided copper clad laminates 1D of layers L7 to L10 is fabricated. Then, a molding process is added to the PP and the double-sided copper clad laminates 1D of layers L7 to L10. The molding process involves opening windows at the positions of the PP and the double-sided copper clad laminates 1D of layers L7 to L10 corresponding to the preset embedded copper block 20. The thickness of the embedded copper block 20 is greater than the lamination thickness of the PP and the double-sided copper clad laminates 1D of layers L7 to L10. Specifically, in this embodiment, the thickness of the embedded copper block 20 is 0.05mm to 0.1mm greater than the lamination thickness at the position of the embedded copper block 20. S2: Layer stacking and riveting process: After stacking and hot-melting the double-sided copper clad boards 1D and PP layer 13 prepared in step S1, they are riveted together to obtain multiple 10-layer unit circuit boards 1C from L1 to L10. S3: Pressing process, including... S3.1: Place the copper embedding block 20. Place the prepared copper embedding block 20 into the open copper embedding position on the 10-layer unit circuit board 1C. S3.2: Pre-stack the multiple 10-layer unit circuit boards 1C obtained in step S2 in a tray. Two 10-layer unit circuit boards 1C are arranged in each layer in each tray, for a total of two layers of 10-layer unit circuit boards 1C. The bottom layer of the unit circuit board has a lower buffer layer on its bottom surface, and the top layer of the unit circuit board has an upper buffer layer on its top surface. An intermediate buffer layer is provided between adjacent unit circuit boards in the middle layer. The upper buffer layer and the lower buffer layer have the same thickness, but the upper buffer layer is thicker than the intermediate buffer layer. S3.3: After pre-stacking is completed, the multiple unit circuit boards are put into the press equipment for synchronous pressing to obtain multiple pressed 10-layer unit circuit boards 1C; S4: Outer layer processing; S5: The subsequent process completes production.

[0039] In step S1 above, the embedded copper block 20, PP layer, and each double-sided copper clad laminate 1D are fabricated separately. After the PP layer is cut and the inner layer of the double-sided copper clad laminate 1D is fabricated, the PP layer and each double-sided copper clad laminate 1D of layers L7 to L10 are windowed to reserve space for the embedded copper block 20. The thickness of the embedded copper block 20 is set to be greater than the lamination thickness of layers L7 to L10, which can effectively prevent the copper block from sinking, thereby solving the problem of poor substrate connection caused by the copper block sinking. In step S2 above, after the embedded copper block 20, PP layer, and each double-sided copper clad laminate 1D are fabricated, the double-sided copper clad laminate 1D and PP layer are laminated and riveted. In this embodiment, to strengthen the riveting... To ensure stability and prevent layer misalignment caused by interlayer errors during subsequent work and lamination, eight rivets are used for riveting and fixing to obtain the 10-layer unit circuit board 1C to be laminated. To prevent the PP layers to be laminated from mixing with other PP materials, the workbench surface is cleaned from cutting to lamination of the PP layers, thereby protecting the surface cleanliness of the board after subsequent hot-melt lamination. Dragging the unit circuit board is prohibited during the lamination process to ensure the subsequent lamination process. In step S3 above, during the lamination process, the embedded copper block 20 is first placed at the windowed embedded copper position on the unit circuit board to be laminated. Specifically, to strengthen the bonding force between the embedded copper block 20 and the 10-layer unit circuit board 1C, step S3...Before placement in step 1, the core board in the embedded copper block 20 and the double-sided copper-clad laminate 1D is browned to prevent delamination and board bursting during pressing. Then, pre-stacking is performed. Before pre-stacking, a suitable tray is selected, and the unit circuit boards to be pressed are arranged side by side in the tray. In this embodiment, two rows are arranged side by side in the tray, with two layers pre-stacked in each row, which is equivalent to four unit circuit boards per tray. To prevent damage to the inner layer boards due to excessive pressure during mechanical pressing, buffer layers are set between the bottom unit circuit boards, between adjacent unit circuit boards, and on the upper surface of the top unit circuit board during the pre-stacking process. The upper and lower buffer layers are larger than the middle buffer layer. In this embodiment, the buffer material of the buffer layers is all new kraft paper. Kraft paper has good tensile strength and low cost, and new kraft paper can also prevent delamination and board bursting during pressing. The inner layer board was damaged due to the old and torn kraft paper. After adopting this pre-stacking scheme, the lamination process is carried out. On the one hand, it effectively improves the lamination efficiency of the lamination process. On the other hand, the setting of the buffer layer plays a good protective role for the unit circuit board. After lamination, the 10-layer unit circuit board 1C is processed by the outer layer process and the post-process. The post-process includes blind milling, etching and forming process, inspection process and packaging process. The blind milling process is to blindly pick up the position of the buried copper block 20 by controlling the depth of milling, so that the edge of the slot of the buried copper block 20 is set in a stepped shape. The etching process uses alkaline solution etching. The inspection process includes electrical testing, FQC and OQC finished product quality inspection, thereby ensuring that the 10-layer board meets the product specifications and thus producing the required circuit board. Specifically, in this embodiment, in step S3.1 above, the copper block browning is performed using different parameters depending on the thickness of the embedded copper block 20. To avoid poor connection between the copper block and the substrate, the thickness of the embedded copper block 20 is 0.05mm-0.1mm greater than the pressing thickness at the embedded copper block 20 position. Within this range, the browning speed of the embedded copper block 20 is 2m / min, and the baking temperature and time after browning are 120°C and 30min, respectively. The browning speed of the double-sided copper-clad laminate 1D is 3.5m / min, and the baking parameters are 120°C*60min. Furthermore, to ensure the connection between the copper block and the PP layer 13 during hot-melt lamination... The contact area is brown; in this example, the fusion temperature is 300°C and the fusion time is 45 seconds; during the pre-stacking process, each tray is pre-stacked with 2 layers. Due to excessive mechanical stacking pressure, which could damage the inner circuit boards, specifically, 20 sheets of brand-new kraft paper are used as buffer boards 30 on the top and bottom layers of the 10-layer unit circuit board 1C. Since the pressure on the inner layers is less than that on the outer layers, 5 sheets of brand-new kraft paper are used as buffer pads 40 between adjacent internal unit circuit boards. These pads fill the pressure loss caused by the copper thickness exceeding the lamination thickness, preventing deformation or damage to the unit circuit boards during lamination.

[0040] In the description of this invention, it should be understood that terms such as "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" 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 invention 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 limiting this invention.

[0041] Furthermore, 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. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0042] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0043] The above embodiments are merely specific examples of the present invention, and their descriptions are quite specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these obvious substitutions all fall within the protection scope of the present invention.

Claims

1. A method for manufacturing a remote radio frequency remote unit circuit board, characterized in that, S1: Fabrication of inner layer circuits, PP layer and embedded copper block (20) of each double-sided copper clad laminate (1D), wherein, after the inner layer circuits of double-sided copper clad laminate (1D) of L(n-3) to Ln layers are fabricated, a molding process is added to the PP and double-sided copper clad laminate (1D) of L(n-3) to Ln layers respectively. The molding process is to open the window at the position corresponding to the PP and double-sided copper clad laminate (1D) of L(n-3) to Ln layers and the preset embedded copper block (20). The thickness of the embedded copper block (20) is greater than the bonding thickness of the PP and double-sided copper clad laminate (1D) of L(n-3) to Ln layers, wherein n is an even number greater than or equal to 6; S2: Layer stacking and riveting process: After stacking and hot-melting the double-sided copper clad boards (1D) made in step S1 with the PP layer, they are riveted together to obtain multiple n-layer unit circuit boards from L1 to Ln. S3: Pressing process, including... S3.1: Place the embedded copper block (20), and place the prepared embedded copper block (20) into the windowed embedded copper position on the n-layer plate; S3.2: Pre-stack the multiple n-layer unit circuit boards obtained in step S2 in a tray. Each tray contains two n-layer unit circuit boards per layer, for a total of m layers of n-layer unit circuit boards. The bottom n-layer unit circuit board has a lower buffer layer on its bottom surface, and the top n-layer unit circuit board has an upper buffer layer on its top surface. An intermediate buffer layer is provided between adjacent n-layer unit circuit boards in the middle layer. The upper buffer layer and the lower buffer layer have the same thickness, and the upper buffer layer is greater than the thickness of the intermediate buffer layer. Here, m is a natural number greater than 1. S3.3: After pre-stacking is completed, the boards are placed in a press machine to perform synchronous pressing of multiple n-layer unit circuit boards, resulting in multiple pressed n-layer unit circuit boards. S4: Outer layer graphic processing steps; S5: The subsequent process completes production.

2. The method for manufacturing a remote radio frequency remote unit circuit board according to claim 1, characterized in that, In step S3.2 above, before pre-stacking, an ordinary aluminum sheet (90) is placed on the copper foil on the side of the buried copper block (20) of each n-layer unit circuit board.

3. The method for manufacturing a remote radio frequency remote unit circuit board according to claim 1, characterized in that, The outer layer patterning process described in step S4 above includes a grinding process, an electroplating process, a drilling process, a hole-filling process, and a controlled-depth milling process. The grinding process is performed in five steps, with the first grinding step being the process after the pressing treatment. The electroplating process includes a plate electroplating process and a pattern electroplating process. The drilling process includes a mechanical drilling process and a controlled-depth drilling process. The hole-filling process is the process after the controlled-depth drilling process.

4. The method for manufacturing a remote radio frequency remote unit circuit board according to claim 3, characterized in that, The grinding process is divided into a first grinding and a second grinding. The first grinding passes through the sand belt section, the ceramic section and the non-woven fabric section, and the board entry direction is the long side of the embedded copper block (20). The second grinding only passes through the non-woven fabric section, and the board entry direction is the long side or short side of the embedded copper block (20) according to the residual adhesive. The residual adhesive is the sand belt or ceramic slag left over from the first grinding.

5. A method for manufacturing a remote radio frequency remote unit circuit board according to claim 4, characterized in that, The plate electroplating process includes a first plate electroplating process and a second plate electroplating process. The first plate electroplating process is a process following the first grinding process. The second plate electroplating process is a process following the fourth grinding process. The fourth grinding process is a process following the mechanical drilling process. The second plate electroplating process uses a low current density and involves long-term electroplating.

6. A method for manufacturing a remote radio frequency remote unit circuit board according to claim 5, characterized in that, The patterning process includes an outer patterning process, a patterning electroplating process, and a film removal process. The patterning process includes a first patterning process and a second patterning process. The first patterning process is a process before the second grinding process, and the second grinding process is a process after the first board electroplating process. The first patterning process is copper plating on the embedded copper block (20) and around the embedded copper block (20). The second patterning process is a process after the second board electroplating process. The second patterning process is copper plating at the copper block position on the Ln surface of the board.

7. A method for manufacturing a remote radio frequency remote unit circuit board according to claim 6, characterized in that, The mechanical drilling process is a process following the third grinding process, which is a process following the first drawing process. The mechanical drilling process takes the L1 side of the board as the positive drilling direction. The mechanical drilling process is divided into two drilling operations. The first drilling simultaneously drills two through holes, namely the first through hole (50) and the second through hole (60). The second drilling drills a third through hole (70). The diameter of the first drilling is larger than that of the second drilling, and the first through hole (50), the second through hole (60), and the third through hole (70) are distributed at equal distances from each other and move toward the buried copper block (20) in sequence.

8. A method for manufacturing a remote radio frequency remote unit circuit board according to claim 7, characterized in that, The controlled depth drilling process is a process following the second drawing and electrical process. The controlled depth drilling process uses the Ln surface of the plate as the forward drilling direction. The controlled depth drilling process is a single drilling operation. The hole drilled by the controlled depth drilling process is a back drill hole (80). The diameter of the back drill hole (80) is larger than the diameter of the first through hole (50). The back drill hole (80) and the third through hole (70) are concentrically distributed.

9. A method for manufacturing a remote radio frequency remote unit circuit board according to claim 8, characterized in that, The hole-plugging process uses resin material to plug the second through hole (60) and the back drill hole (80) respectively, and then performs copper plating and hole-covering electroplating processes on the second through hole (60).

10. A method for manufacturing a remote radio frequency remote unit circuit board according to claim 3, characterized in that, The controlled depth milling process is the process after the fifth grinding process, and the fifth grinding process is the process after the hole plugging process. The controlled depth milling process mills grooves from Ln to L(n-1) layers of the embedded copper block (20) to obtain grooves. The width of the grooves is smaller than the width of the embedded copper block (20). The controlled depth milling uses a CCD milling machine. A white pad is provided between the CCD milling machine and the n-layer board. The white pad has a groove.

Images