A method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board

Abstract

The present invention discloses a method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board, which relates to the field of circuit board production. The method includes first performing engineering design, performing pre-processing and preparation after the engineering design is completed, performing hole metallization control of the high-frequency microwave board after the pre-processing and preparation is completed, performing copper plating after the hole metallization control of the high-frequency microwave board is completed, and performing metal-based chemical gold plating after the copper plating is completed. In the post-pressed multi-layer high-frequency metal-based carbon oil circuit board production method, the dielectric layer of the multi-layer high-frequency metal substrate is generally a high-frequency material. The multi-layer high-frequency microwave board is first prepared, then pressed together with the metal base, and then surface treated and formed. The carbon oil board is generally used on an FR4 board and is screen-printed with ordinary mesh. The resistance and thickness errors are relatively large. The produced post-pressed high-frequency metal-based carbon oil circuit board has good heat dissipation and excellent signal transmission performance. The carbon oil thickness and resistance meet customer requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit board production, in particular to a method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board. Background Art

[0002] Post-pressed multi-layer high-frequency metal-based carbon oil printed circuit board is a circuit board specially used for high-frequency, high-power electronic equipment, combining the advantages of metal substrate and special materials.

[0003] In the prior art, carbon oil sheets are generally used on FR4 sheets (epoxy resin) and are screen printed with ordinary mesh, resulting in large errors in resistance and thickness.

[0004] In order to overcome the above shortcomings, the Chinese patent of the prior art (Announcement No. CN102159029B) discloses a method for manufacturing a high-frequency aluminum-based circuit board, which includes the following steps: step 1, making a photo-painted template; step 2, making a material and drilling holes; step 3, making a surface pattern; step 4, making an electroplating and etching; step 5, treating solder mask, characters and surface solderability; step 6, forming and manufacturing a finished high-frequency aluminum-based circuit board, which not only has high manufacturing precision and effectively improves product quality and work efficiency, but also has stable performance of the high-frequency aluminum-based circuit board; In order to overcome the above shortcomings, the Chinese patent of the prior art (Announcement No. CN103327736B) discloses a highly thermally conductive, insulating metal-based printed circuit board, comprising a metal substrate, a metal transition layer formed sequentially by magnetron sputtering, a ceramic layer formed by arc ion plating, and a metal conductive layer formed on the ceramic layer; the ceramic layer has a thermal conductivity greater than 100 W / mK. By depositing the metal transition layer and the highly thermally conductive ceramic layer on the metal substrate, a highly integrated integrated printed circuit board can be formed as a circuit board substrate. The preparation method has easy-to-control process parameters, simple steps, stable and reliable product quality, high production efficiency, and low preparation cost.

[0005] Although the existing technology can overcome the above-mentioned shortcomings, there are still other problems in its operation process, such as: the preparation of the post-pressed multi-layer high-frequency metal-based carbon oil circuit board is relatively cumbersome, the operation key positions are complicated, and it is not conducive to saving operation time. At the same time, the post-pressed multi-layer high-frequency metal-based carbon oil circuit board produced has poor heat dissipation effect and poor signal transmission performance. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board, so as to solve the problem proposed in the above background technology that the preparation of the post-pressed multi-layer high-frequency metal-based carbon oil circuit board is rather cumbersome and the operation key positions are complicated, which is not conducive to saving operation time. At the same time, the post-pressed multi-layer high-frequency metal-based carbon oil circuit board produced has poor heat dissipation effect and poor signal transmission performance.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board, S1, engineering design; S2, pretreatment preparation; S3, hole metallization control of the high-frequency microwave board; S4, copper plating processing; S5, metal-based chemical gold plating processing; S6, metal-based machining; S7, pressing the metal substrate and the high-frequency microwave board; S8, carbon oil control; S9, final inspection and shipment; specifically comprising the following steps: S1, engineering design: when pressing the metal substrate and the high-frequency microwave board, the adhesive used The size of the film, its shape and the holes and slots should be appropriately reduced by 0.2-0.5mm to reserve space for the glue to flow out; the circuit film of the high-frequency microwave board will become smaller when the film is compensated due to the corrosion of the liquid, so the film should be appropriately increased; S2, pretreatment preparation: cutting: set the size of the work board according to the equipment process capability and board utilization rate, and then cut the board into the corresponding size; inner layer wet film: transfer the pattern to the work board according to the data. Quality points: line width / spacing must be qualified and there must be no poor exposure ; S3. Hole metallization control of high-frequency microwave boards: The material of high-frequency microwave boards is generally Teflon or ceramic mixed with FR4, and plasma cleaning is required before chemical copper plating; S4. Copper plating processing: After copper plating, improve the electrical performance requirements; S5. Metal-based chemical gold plating processing: All liquid tanks are installed with pneumatic vibration, and ultrasonic cleaning is installed in the water washing tank before entering the gold tank to ensure that the liquid in the blind hole is cleaned. A special gold immersion hanging basket is used, and the surface coating of the hanging basket must have a certain degree of elasticity. There should be no hanging basket marks around the metal base; S6 1. Metal base machining: After drilling and removing burrs, the size of the gong must meet the requirements and there must be no burrs / flashes; S7. Pressing of metal substrate and high-frequency microwave board: When pressing, use pins to fix the metal base. Vacuum for 5-10 minutes before pressing. After pressing, ultrasonic scanning must be performed. There must be no voids in the bonding sheet and the glue must not overflow; S8. Carbon oil control: Boards with qualified appearance are sent for carbon oil printing, and carbon oils of different square resistances are selected according to requirements; S9. Final inspection and shipment: Products are inspected according to IPC standards or customer standards.

[0008] Furthermore, in step S1, the drawings are optimized and designed according to the process capabilities, including pre-stretching of the film, circuit compensation, and drilling compensation. The circuit compensation is to increase the single side by 0.01-0.03mm on the original basis. The specific data is determined according to the copper thickness. The drilling compensation determines the size of the drill hole according to the finished product aperture and plating thickness. At the same time, another plate is assembled to convert it into production data within the company.

[0009] Furthermore, in step S2, the material cutting: the size of the working board is set according to the equipment process capability and the board utilization rate, and then the board is cut into the corresponding size. The inner layer wet film: according to the customer's information, the pattern is transferred to the working board. The quality points are: the line width / spacing must be qualified and there must be no poor exposure.

[0010] Furthermore, step S3, vacuum etching: using a vacuum etcher, using acidic etching solution, all the graphics required by the customer are etched out. The quality of this process must be focused on and the line width / line spacing must be controlled within the qualified range; the interlayer deviation of the upper and lower layers must be controlled within 25um. The vacuum etcher can ensure the uniformity of the circuit of the entire working board after etching. Automatic optical inspection: using an automatic scanning detection instrument to check the quality of the circuit after etching, confirm whether there is an open short circuit, whether there is a gap or a bump, pressing: using a vacuum hot press, using the corresponding pressing plate program, different circuit layers are pressed together, quality points: the board thickness and tolerance must be qualified, and there is no delamination / blistering problem with thermal shock and reflow soldering, drilling: the purpose of this process is to drill through holes on the board surface, and the subsequent process can be chemically copper plated to achieve electrical conductivity of the upper and lower layers of copper. In this process, the drilling quality must be strictly controlled, the roughness inside the hole is not allowed to be too large, and burrs, flashes, substrate damage / deformation and other problems are not allowed.

[0011] Furthermore, the step S4, chemical copper plating: is to use chemical reaction to plate a thin layer of copper in the drilled hole to achieve electrical conductivity between the upper and lower layers of the board, electroplating copper: thickening the copper in the hole and the copper on the surface to meet customer requirements to ensure the electrical performance requirements of the end customer, graphic transfer: according to the customer's information, transfer the graphic from the negative to the work board, quality points: line width / spacing must be qualified, vacuum etching: using a vacuum etcher, using acidic etching solution to etch out all the graphics required by the customer, the quality of this process must be focused on, the line width / spacing must be controlled within the qualified range; the interlayer deviation between the upper and lower layers must be controlled within 25um, solder mask: according to customer requirements, print a layer of insulating ink on the circuit board surface, but the pads of the plug-in and the patch must be fully exposed, characters: use a screen or character inkjet machine to print some of the customer's identification letters, graphics and company logos for easy identification by end customers.

[0012] Furthermore, in step S5, since the metal base has blind holes and blind grooves, the liquid medicine in the blind holes / grooves cannot be exchanged during the chemical gold plating process, resulting in the appearance of black holes. Therefore, in a dedicated production line, all liquid medicine tanks are installed with pneumatic vibration, and ultrasonic cleaning is installed in the water washing tank before entering the gold tank to ensure that the liquid medicine in the blind holes is cleaned.

[0013] Furthermore, in step S6, a diamond-coated drill bit is used for drilling, and the drilling is carried out in sections. The metal base thickness is 3mm, and the holes are drilled in 3-5 sections. Special drilling parameters are used: cutting speed 1-2m / min, retracting speed 8-10m / min, rotation speed 30KRPM, cutting amount 0.1-0.2mm / turn, drill life 500-1000 holes / piece, and number of stacks 1PNL / stack. Using these parameters for production can effectively control the roughness in the hole and burrs and flash on the plate surface. The shape processing is carried out using a CNC machining center, using a coated double-edged gong cutter. The process parameters include: cutting speed 2-3m / min, retracting speed 8-10m / min, rotation speed 25-30KRPM, gong cutter life 3-5m / piece, and number of stacks 1PNL / stack. The size of the gong must meet the requirements and there must be no burrs / flaking.

[0014] Furthermore, in step S7, during lamination, pins are used to fix the metal base, then the bonding sheet is stacked, and then the high-frequency microwave PCB is placed according to the pin holes to align the PCB, bonding sheet and metal base so that they do not deviate during the lamination process. Special auxiliary materials are also used on the upper and lower parts. The auxiliary material is a release film that can withstand a maximum temperature of 350°C. The use of this auxiliary material can ensure the lamination effect and there will be no residual glue on the board surface. Before lamination, vacuum is applied for 5-10 minutes, and then special lamination parameters are used: furnace temperature of 120°C, lamination temperature of 190-220°C, pressure of 1.5-3.5MPa, of which the conditions of 210°C and 3.5MPa must be maintained for 90-120 minutes, and the total lamination time is 240 minutes. Ultrasonic scanning must be performed after lamination. There must be no voids in the bonding sheet and the glue must not overflow.

[0015] Furthermore, in step S8, the boards with qualified appearance are sent for carbon oil printing. Carbon oils of different square resistance are selected according to customer requirements. A 200-250 mesh pure steel screen is used for silk screen printing. Carbon oil is printed at the required position. Then, an IR furnace is used to bake the carbon oil. A laser film thickness tester is used to measure the thickness of the carbon oil. A special test stand is used to measure the carbon resistance. Boards with high carbon resistance are directly scrapped. Points with low carbon oil are cut using a laser cutting machine until the resistance value reaches the standard.

[0016] Furthermore, in step S9, the products are inspected according to IPC standards or customer standards, and qualified products can be packaged and shipped according to the packaging method required by the customer.

[0017] Compared with the existing technology, the present invention has the following advantages: 1. The dielectric layer of the multi-layer high-frequency metal substrate is generally made of high-frequency material. The multi-layer high-frequency microwave board is first made, then pressed together with the metal base, and then surface treated and formed. The carbon oil board is generally used on the FR4 board and is screen-printed with ordinary mesh, resulting in relatively large errors in resistance value and thickness;

[0018] Furthermore, the produced post-pressed high-frequency metal-based carbon oil circuit board has good heat dissipation, excellent signal transmission performance, and the carbon oil thickness and resistance meet customer requirements.

[0019] 2. The operation is simple. First, make the multi-layer high-frequency microwave circuit board, that is, complete the surface treatment, molding process and testing, check the appearance of qualified, and then press it together with the metal substrate. The board that has passed the test in all aspects can be silk-screened with carbon oil using a steel screen. The board that meets the resistance value, thickness and appearance can be delivered to the customer. It can get the required products quickly and conveniently, saving the time required for work. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall process of the present invention;

[0021] Figure 2 This is a schematic diagram of the process structure of the present invention;

[0022] Figure 3 Schematic diagram of the key technology of the present invention. DETAILED DESCRIPTION

[0023] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0024] Example 1: Figure 1-Figure 3 The technical solution shown is a method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board. To solve the problems of poor heat dissipation, poor signal transmission performance, and carbon oil thickness and resistance values ​​that do not meet customer requirements for post-pressed high-frequency metal-based carbon oil circuit boards, the following steps are disclosed: S1, engineering design; S2, pretreatment preparation; S3, hole metallization control of the high-frequency microwave board; S4, copper plating processing;

[0025] S5, metal-based chemical gold plating processing; S6, metal-based machining; S7, lamination of metal substrate and high-frequency microwave board; S8, carbon oil control; S9, final inspection and shipment; specifically includes the following steps:

[0026] S1. Engineering design: When the metal substrate and the high-frequency microwave board are pressed together, the adhesive sheet used should be appropriately reduced by 0.2-0.5mm around its outer shape and around the holes and slots to reserve space for the glue to flow out; the circuit film of the high-frequency microwave board will become smaller due to the corrosion of the liquid during film compensation, so the film should be appropriately increased; S2. Pretreatment preparation: Cutting: Set the size of the work plate according to the equipment process capability and the utilization rate of the plate, and then cut the plate into the corresponding size; Inner wet film: Transfer the pattern to the work plate according to the data. Quality points: Line Width / pitch must be qualified, with no exposure defects; S3. Hole metallization control for high-frequency microwave boards: High-frequency microwave boards are generally made of a mixture of Teflon or ceramic and FR4, and plasma cleaning is required before electroless copper plating; S4. Copper plating: After copper plating, electrical performance requirements must be improved; S5. Metal-based electroless gold plating: All solution tanks must be pneumatically vibrated, and ultrasonic cleaning must be installed in the water washing tank before entering the gold tank to ensure that the solution in the blind holes is cleaned. A special gold immersion basket must be used, and the surface coating of the basket must have a certain degree of elasticity. There must be no basket marks around the metal base;

[0027] S6. Metal base machining: After drilling and removing burrs, the size of the hole must meet the requirements and there must be no burrs or flashes; S7. Pressing of metal substrate and high-frequency microwave board: During pressing, use pins to fix the metal base, vacuum for 5-10 minutes before pressing, and perform ultrasonic scanning after pressing. There must be no voids in the bonding sheet and the glue must not overflow; S8. Carbon oil control: Boards with qualified appearance are sent for carbon oil printing, and carbon oils of different square resistances are selected according to requirements; S9. Final inspection and shipment: Products are inspected according to IPC standards or customer standards.

[0028] Step S1: Based on the process capability, the drawings are optimized and designed, including pre-stretching of the film, compensation of the circuit, and compensation of the drilling. The circuit compensation is to increase the original one side by 0.01-0.03mm, the specific data should be determined according to the copper thickness. The drilling compensation is determined by the finished product aperture and the plating thickness to determine the size of the drilling. At the same time, the plate is assembled to convert it into the company's internal production data. Step S2, cutting: set the size of the working board according to the equipment process capability and the board utilization rate, and then cut the board into the corresponding size. Inner layer wet film: transfer the graphics to the working board according to the customer's information. Quality points: line width / spacing must be qualified and there must be no poor exposure. Step S3, vacuum etching: use a vacuum etcher and use acidic etching solution to etch out all the graphics required by the customer. The quality of this process must be focused on, and the line width / line spacing must be controlled within the qualified range; the interlayer deviation of the upper and lower layers must be controlled within 25um. The vacuum etching machine can ensure the uniformity of the circuit of the entire working board after etching. Automatic optical inspection: Use automatic scanning detection equipment to check the quality of the circuit after etching to confirm whether there is an open short circuit, whether there is a gap or a bump. Pressing: Use a vacuum hot press and the corresponding pressing program to press different circuit layers together. Quality points: The thickness and tolerance of the board must be qualified, and there must be no delamination / blistering problems with thermal shock and reflow soldering. Drilling: The purpose of this process is to drill through holes on the board surface, and then chemical copper plating can be performed in the later process to achieve electrical conductivity of the upper and lower layers of copper. In this process, the drilling quality must be strictly controlled, the roughness inside the hole is not allowed to be too large, and burrs, flashes, damage / deformation of the substrate are not allowed. Step S4, chemical copper plating: is to drill holes A thin layer of copper is plated in the hole by chemical reaction to achieve electrical conductivity between the upper and lower layers of the board. Electroplating copper: thicken the copper in the hole and the copper on the surface to meet customer requirements to ensure the electrical performance requirements of the end customer. Graphic transfer: transfer the graphics from the negative to the work board according to the customer's information. Quality points: line width / spacing must be qualified. Vacuum etching: use a vacuum etcher and acidic etching solution to etch out all the graphics required by the customer. The quality of this process must be focused on control. Line width / line spacing must be controlled within the qualified range; the interlayer deviation of the upper and lower layers must be controlled within 25um. Solder mask: according to customer requirements, print a layer of insulating ink on the surface of the circuit board, but the pads of the plug-in and the patch must be fully exposed. Characters: Use a screen or inkjet printer to print the customer's logo, graphics, and company logo for easy identification by end customers. Step S5: Because the metal substrate has blind holes and slots, the chemical plating process prevents the solution in the blind holes / slots from being exchanged, resulting in black holes. Therefore, production is performed on a dedicated production line. All solution tanks are pneumatically vibrated, and ultrasonic cleaning is installed in the water washing tank before the gold tank to ensure that the solution in the blind holes is completely cleaned. Step S6: Drilling is performed using a diamond-coated drill bit in sections. The metal substrate is 3mm thick and is drilled in 3-5 sections. Special drilling parameters are used: down-cut speed 1-2m / min, retract speed 8-10m / min, rotation speed 30kRPM, and stock removal volume 0.1-0.2mm / turn, drill life 500-1000 holes / piece, number of stacks 1PNL / stack. Using these parameters for production can effectively control the roughness inside the hole and burrs and flash on the board surface. The shape processing is carried out using a CNC machining center, using a coated double-edged gong cutter. The process parameters include: down cutter speed 2-3m / min, retract cutter speed 8-10m / min, rotation speed 25-30KRPM, gong cutter life 3-5m / piece, number of stacks 1PNL / stack. The gong size must meet the requirements and there must be no burrs / flash. Step S7, when pressing, use pins to fix the metal base, then stack the bonding sheet, and then place the high-frequency microwave PCB according to the pin holes to align the PCB, bonding sheet and metal base. There is no offset during the pressing process. Special auxiliary materials are also used on the upper and lower parts. This auxiliary material is a release film that can withstand the highest temperature: 350℃. Using this auxiliary material can ensure the pressing effect and there will be no residual glue on the board surface. Vacuum for 5-10 minutes before pressing, and then use special The pressing parameters are: furnace entry temperature 120°C, pressing temperature 190-220°C, pressure 1.5-3.5MPa, with 210°C and 3.5MPa maintained for 90-120 minutes, for a total pressing time of 240 minutes. After pressing, ultrasonic scanning is performed. The bonding sheet must be free of voids and glue overflow. In step S8, boards that meet the required appearance are sent for carbon ink printing. Carbon inks of varying square resistances are selected according to customer requirements. A 200-250 mesh pure steel screen is used for screen printing. The carbon ink is then applied to the required locations using an IR furnace. The carbon ink thickness is measured using a laser film thickness tester, and carbon resistance is measured using a dedicated test stand. Products with excessively high resistance are discarded. Points with low resistance are cut using a laser cutter until the resistance reaches the specified value. In step S9, the products are inspected according to IPC standards or customer specifications. Qualified products are packaged and shipped according to the customer's packaging method.

[0029] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A post-pressed multi-layer high-frequency metal-based carbon oil circuit board production method, comprising S1, engineering design; S2, pretreatment preparation; S3, hole metallization control of the high-frequency microwave board; S4, copper plating; S5, metal-based chemical gold plating; S6, metal-based machining; S7, lamination of the metal substrate and the high-frequency microwave board; S8, carbon oil control; S9, final inspection and shipment. It is characterized by: The specific steps include: S1. Engineering Design: When the metal substrate is pressed together with the high-frequency microwave board, the adhesive sheet used should be appropriately reduced by 0.2-0.5mm around its shape and around the holes and slots to reserve space for the glue to flow out; The circuit film of the high-frequency microwave board will become smaller when the film is eroded by the solution during film compensation, so the film should be increased appropriately. S2. Pretreatment preparation: Cutting: The size of the work plate is set according to the equipment process capability and plate utilization rate, and then the plate is cut into the corresponding size; Inner wet film: transfer the graphics to the work board according to the data. Quality points: line width / spacing must be qualified and there must be no poor exposure; S3. Hole metallization control of high-frequency microwave boards: The material of high-frequency microwave board is Teflon or ceramic mixed with FR4, and plasma cleaning is required before chemical copper plating; S4, copper plating processing: After copper plating, the electrical performance requirements are improved; S5. Metal-based chemical gold plating processing: All the liquid medicine tanks are installed with pneumatic vibration, and ultrasonic cleaning is installed in the water washing tank before entering the gold tank to ensure that the liquid medicine in the blind hole is cleaned. A special gold sinking hanging basket is used, and the surface coating of the hanging basket must have a certain elasticity, and there should be no hanging basket marks around the metal base; S6. Metal-based machining: After drilling and removing burrs, the hole size must meet the requirements and there must be no burrs or flashes; S7. Lamination of metal substrate and high-frequency microwave board: When pressing, use pins to fix the metal base. Vacuum for 5-10 minutes before pressing. Perform ultrasonic scanning after pressing. There should be no voids in the adhesive sheet and no glue overflow. S8, Carbon oil control: The boards with qualified appearance are sent to be printed with carbon ink, and carbon inks with different square resistances are selected according to requirements; S9, Final Inspection and Shipment: Inspect products according to IPC standards or customer standards.

2. The method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board according to claim 1, characterized in that: In step S1, the drawings are optimized and designed according to the process capabilities, including pre-stretching of the film, circuit compensation, and drilling compensation. The circuit compensation is to increase the single side by 0.01-0.03mm on the original basis. The specific data is determined by the copper thickness. The drilling compensation determines the size of the drill hole based on the finished product aperture and copper thickness. At the same time, a separate plate is assembled to convert it into internal production data.

3. The method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board according to claim 1, characterized in that: Step S2, cutting: the size of the work plate is set according to the equipment process capability and the plate utilization rate, and then the plate is cut into the corresponding size. Inner wet film: according to the customer's information, the pattern is transferred to the work plate. Quality points: the line width / spacing must be qualified and there must be no poor exposure.

4. The method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board according to claim 1, characterized in that: The step S3, vacuum etching: using a vacuum etcher, using acidic etching solution, all the graphics required by the customer are etched out, the quality must be focused on, the line width / line spacing must be controlled within the qualified range; the interlayer deviation of the upper and lower layers must be controlled within 25um, the vacuum etcher can ensure the uniformity of the circuit of the entire working board after etching, automatic optical inspection: using an automatic scanning detection instrument to check the quality of the circuit after etching, confirm whether there is an open short circuit, whether there is a gap or a bump, pressing: using a vacuum hot press, using the corresponding pressing plate program, different circuit layers are pressed together, quality points: the board thickness and tolerance must be qualified, and there is no delamination / blistering problem during thermal shock and reflow soldering, drilling: the purpose is to drill through holes on the board surface, and the subsequent process can be chemically copper plated to achieve electrical conductivity of the upper and lower layers of copper. The drilling quality must be strictly controlled, the roughness inside the hole is not allowed to be too large, and burrs, flashes, and substrate damage and deformation are not allowed.

5. The method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board according to claim 1, characterized in that: Step S4, chemical copper plating: is to use chemical reaction to plate a thin layer of copper in the drilled hole to achieve electrical conductivity between the upper and lower layers of the board, electroplating copper: thickening the copper in the hole and the copper on the surface to meet customer requirements to ensure the electrical performance requirements of the end customer, pattern transfer: according to the customer's information, transfer the pattern from the negative to the work board, quality points: line width / spacing must be qualified, vacuum etching: using a vacuum etcher, using acidic etching solution to etch out all the patterns required by the customer, quality must be focused on, line width / spacing must be controlled within the qualified range; the interlayer deviation between the upper and lower layers must be controlled within 25um, solder mask: according to customer requirements, print a layer of insulating ink on the circuit board surface, but the pads of the plug-in and patch must be fully exposed, characters: use a screen or character inkjet machine to print some customer's identification letters, graphics and company logos for easy identification by end customers.

6. The method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board according to claim 1, characterized in that: In step S5, since the metal base has blind holes and blind grooves, the liquid medicine in the blind holes / grooves cannot be exchanged during the chemical gold plating process, resulting in the appearance of black holes. Therefore, the process is produced on a dedicated production line, and all liquid medicine tanks are installed with pneumatic vibrations. Ultrasonic cleaning is installed in the water washing tank before entering the gold tank to ensure that the liquid medicine in the blind holes is cleaned.

7. The method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board according to claim 1, characterized in that: In step S6, a diamond-coated drill bit is used for drilling, and the drilling is carried out in sections. The metal base thickness is 3mm, and the holes are drilled in 3-5 sections. Special drilling parameters are used: a lower cutter speed of 1-2m / min, a retracting cutter speed of 8-10m / min, a rotation speed of 30KRPM, a cutting amount of 0.1-0.2mm / turn, a drill bit life of 500-1000 holes / piece, and a stack of 1PNL / stack. Using these parameters for production can effectively control the roughness in the hole and the burrs and flashes on the plate surface. The shape processing is carried out using a CNC machining center using a coated double-edged gong cutter. The process parameters include: a lower cutter speed of 2-3m / min, a retracting cutter speed of 8-10m / min, a rotation speed of 25-30KRPM, a gong cutter life of 3-5m / piece, and a stack of 1PNL / stack. The size of the gong must meet the requirements and there must be no burrs or flashes.

8. The method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board according to claim 1, characterized in that: In step S7, during lamination, pins are used to fix the metal base, then the bonding sheet is stacked, and the high-frequency microwave PCB is placed according to the pin holes to align the PCB, bonding sheet and metal base. There is no deviation during the lamination process. Special auxiliary materials are also used on the upper and lower parts. The auxiliary material is a release film that can withstand a maximum temperature of 350°C. The use of this auxiliary material can ensure the lamination effect and there will be no residual glue on the board surface. Before lamination, vacuum is applied for 5-10 minutes, and then special lamination parameters are used: furnace entry temperature 120°C, lamination temperature 190-220°C, pressure 1.5-3.5MPa, of which the conditions of 210°C and 3.5MPa must be maintained for 90-120 minutes, and the total lamination time is 240 minutes. Ultrasonic scanning is performed after lamination. There must be no voids in the bonding sheet and the glue must not overflow.

9. The method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board according to claim 1, characterized in that: In step S8, the boards with qualified appearance are sent to be printed with carbon oil. Carbon oils of different square resistance are selected according to customer requirements. A 200-250 mesh pure steel screen is used for silk screen printing. The carbon oil is printed at the required position. Then, an IR furnace is used to bake the carbon oil. A laser film thickness tester is used to measure the thickness of the carbon oil. A special test stand is used to measure the carbon resistance. The boards with high carbon resistance are directly scrapped. The points with low carbon oil are cut using a laser cutting machine until the resistance value reaches the standard.

10. The method for producing a post-pressed multi-layer high-frequency metal-based carbon oil circuit board according to claim 1, characterized in that: In step S9, the products are inspected according to IPC standards or customer standards. If they are qualified, they can be packaged and shipped according to the packaging method required by the customer.

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