Manufacturing method of LEO antenna board with embedded PIN switch

Abstract

The invention discloses a manufacturing method of an LEO antenna board with an embedded PIN switch. The manufacturing method comprises the following steps: manufacturing a high-frequency core board made of a PTFE material; manufacturing a high-frequency core board made of a PMI material; manufacturing a slotted prepreg; mounting a PIN switch; mixing and pressing the PTFE material and the PMI material; and manufacturing the PCB embedded with the PMI material. According to the invention, the prepreg and the PMI material core plate are slotted, the PIN switch is mounted on the PTFE core plate, and the low-flow glue prepreg is used for lamination, so that the periphery of the PIN switch is protected and isolated by the PMI material; and the mixed pressing of the PTFE material and the PMI material adopts a laminated mixed pressing process of a peripheral frame plate and a slotted cover plate, and the PCB embedded with the PMI material adopts a hole-in-hole design, so that the effect of the high-reliability LEO antenna board embedded with the PIN switch is obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of electronic packaging, and in particular relates to a method for manufacturing a LEO antenna board with an embedded PIN switch. Background Art

[0002] As a frontier area for 5G technology integration, construction of 6G key technologies, and "new infrastructure" technological innovation, low earth orbit (LEO) satellites have become a new research hotspot in recent years. The corresponding PCB stacking architecture of the LEO antenna system adopts a multi-layer design, integrating the antenna layer, power layer, control layer, power network layer, and chip layer. Due to the stringent thermal stress requirements of low-orbit satellites and the low-pressure vacuum environment in which they are located, PCB boards require higher TG and lower CTE to obtain better thermal reliability.

[0003] PIN switch (Programmable Integrable Negative logic) is a four-port component that integrates multiple transistors and resistors. By changing its input level, the output level can be controlled, thereby controlling the circuit. RF PIN switches are widely used in RF systems because they have the characteristics of high controllable power, low loss, fast switching speed, and low cost. Embedded component printed circuit boards can optimize wiring and packaging density, reduce outer solder joints, reduce through holes and lead-in and lead-out wires, thereby reducing signal crosstalk, noise and electromagnetic interference, reducing parasitic component effects, improving overall packaging reliability, improving high-frequency signal transmission quality, and avoiding the influence of external conditions on devices. In view of the application characteristics of low-orbit satellites and RF PIN switches, combining the two to form a LEO antenna board with embedded PIN switches has become one of the current research directions of information and communication technology. However, due to the high pressure required for the flow and curing of the semi-cured sheet during high-frequency board lamination, the PIN switch is prone to undesirable phenomena such as fracturing and crushing. Therefore, it is necessary to provide a method for making a LEO antenna board with embedded PIN switches with high reliability. Summary of the invention

[0004] In order to solve the problems in the prior art, the present invention provides a method for manufacturing a LEO antenna board with an embedded PIN switch, so as to achieve high reliability in the manufacturing of the LEO antenna board with an embedded PIN switch.

[0005] The method for manufacturing the embedded PIN switch LEO antenna board provided by the present invention includes:

[0006] Make high-frequency core board of PTFE material, make high-frequency core board of PMI material; make slotted prepreg; mount PIN switch; mix and press PTFE material and PMI material; make PCB embedded with PMI material.

[0007] Furthermore, the manufacturing of the high-frequency core plate of the PTFE material specifically includes: cutting, pattern transfer, and punching rivet holes;

[0008] Cutting: PTFE materials without copper and with thicknesses of 0.762mm, 0.508mm and 0.203mm are selected for cutting, namely L0102, L0506 and L0708. The size after cutting is 225mm*150mm; the fiber fibers left at the right angles of the board edges and four sides during cutting are removed by mechanical grinding; the board is placed in a vertical oven and baked at 150℃*2H to remove moisture and organic volatiles;

[0009] Pattern transfer: For L0102, L0506, and L0708, film exposure is performed to make alignment PAD and target hole patterns. For L05, the surface mount PIN switch pattern is made. Acid etching is performed according to the designed pattern, and the film is etched cleanly.

[0010] Punching rivet holes: Use OPE punching machine to automatically align by grabbing the target to punch out the rivet holes of L0102, L0506, and L0708 for riveting in the subsequent process;

[0011] High temperature tape: The entire surface of L07 is covered with high temperature tape, and the pattern for retaining the high temperature tape is cut out at the installation position by laser cutting.

[0012] Furthermore, the manufacturing of the high-frequency core board of the PMI material specifically includes: cutting, punching rivet holes, and milling grooves;

[0013] Cutting: Copper-free PMI material with a thickness of 0.508mm is selected for cutting, as L0304, and the size after cutting is 225mm*150mm; the edges and right angles left by the edges of the board and the four sides of the board during cutting are removed by mechanical grinding;

[0014] Punching rivet holes: Use OPE punching machine to punch out rivet holes of L0304 according to the predetermined size for riveting in the subsequent process;

[0015] Milling slot: Use CNC electric milling machine to locate the rivet hole of L0304, and mill the slot for the PIN switch on L0304. The slot size is 0.05-0.1mm larger than the PIN switch.

[0016] Furthermore, the manufacturing of the slotted prepreg comprises: cutting, drilling rivet holes, and slotting;

[0017] Cutting: Use low-flow prepreg with a thickness of 0.092mm for cutting, and the size after cutting is 225mm*150mm;

[0018] Drilling rivet holes: Use a CNC drill to drill rivet holes with a diameter of 3.15mm on the prepreg for riveting in the subsequent process;

[0019] Slotting: Use a CNC electric milling machine to locate the rivet holes on the prepreg and mill out the slot required to embed the PIN switch. The slot size should be 0.05-0.1mm larger than the PIN switch.

[0020] Furthermore, the mounting of the PIN switch specifically includes: printing solder paste, mounting the PIN switch, and reflow soldering;

[0021] Printing solder paste includes: making a steel mesh corresponding to the position of the mounted PIN switch and installing it on a solder paste printer, wherein the viscosity of the solder paste is detected to be 185±10pa.s; adding the solder paste to the steel mesh accordingly, and ensuring that the thickness of the solder paste does not exceed 25% of the height of the scraper blade of the solder paste printer; installing the steel mesh on the solder paste printer and positioning it, and then controlling the scraper on the solder paste printer to repeatedly move on the steel mesh, so that the solder paste passes through the mesh holes on the steel mesh and covers the specific pads of the mounted PIN switch, thereby completing solder paste printing;

[0022] Mounting the PIN switch includes: mounting the PIN switch on the specific pad accordingly, so that the PIN switch is mounted on the specific pad accordingly through solder paste;

[0023] The reflow soldering includes: subjecting the core board after the PIN switch is mounted to the reflow soldering, wherein the reflow soldering includes preheating, constant temperature, reflow, and cooling treatment, wherein the preheating zone is 25-140°C, the time is 100S, and the heating slope is ≤1.2-2.5°C / S; the temperature of the constant temperature zone is controlled at 155-225°C, the time is 165S, and the heating slope is ≤1.2-2.6°C / S; the temperature of the reflow zone is controlled at 220-260°C, the time is 75S, and the heating slope is ≤1.0-2.6°C / S; the peak temperature of the cooling zone is controlled at Tmax-160°C, the peak temperature is 235-260°C, and the cooling slope is -1.0°C / S≤slope≤-2.6°C.

[0024] Furthermore, the mixing and pressing of the PTFE material and the PMI material comprises:

[0025] Browning: Browning is performed on PFTE material L0102, L0506, L0708 and PMI material L0304 before lamination to clean and micro-roughen the board surface and enhance the bonding strength between the inner layer material and the prepreg after lamination;

[0026] Pre-stacking: Fusing is done at the hot melt block positions of L0102, L0506, and L0708. After the core boards and prepregs of each layer are stacked in sequence, riveting is done at the four corner rivet holes with flower rivets;

[0027] Frame board preparation and use: 8 rectangular grooves of 235mm*160mm are milled out in the middle of the FR4 substrate with a thickness of 2.7mm and a size of 650mm*500mm. 1mm board edges are reserved on all sides and in the middle to place the pre-stacked mixed-pressed boards to ensure that the mixed-pressed boards of PTFE material and PMI material will not lose pressure or be over-pressed;

[0028] Preparation and use of the upper cover: mill the corresponding small rectangular grooves on the FR4 substrate with a thickness of 1.0 mm according to the position of the embedded PIN switch, and further rivet the upper cover and the frame to prevent the slotted core board with embedded PIN from collapsing during the pressing process;

[0029] Lamination: Use hydraulic press, use composite materials for buffering, and use specific PFTE material and PMI mixed pressure parameters for lamination; use the conversion process of prepreg from B-stage to C-stage under high temperature and high pressure conditions to bond each layer of core board into one. Specific parameters include

[0030]

[0031] Target hole: according to the target hole pattern, punch the target holes required for drilling and alignment;

[0032] Gong edge: remove the burrs around the gong and grind the edges.

[0033] Furthermore, the production process of the PCB embedded with PMI material specifically includes hole processing process, pattern transfer, acid etching, depth control and uncovering, nickel-gold plating, testing and molding.

[0034] The hole processing steps include mechanical drilling, resin plugging, secondary drilling, chemical copper and electroplating thickened copper.

[0035] The mechanical drilling and laminated boards use special parameters for high-frequency mixed-pressed boards containing PMI materials, and are enlarged by 0.8 mm based on the metallized hole requirements.

[0036] The resin plugging method plugs the holes formed by mechanical drilling with epoxy resin which is easy to process, and then grinds the resin after high temperature curing.

[0037] The secondary drilling is to drill holes at the positions of the original resin plug holes to form a hole-in-hole design structure.

[0038] The chemical copper and electroplated thickened copper utilize the principle of redox reaction to deposit colloidal palladium and copper on the secondary drilled holes. After the conduction is formed, the electroplated thickened copper reaches the required copper thickness.

[0039] Furthermore, the pattern transfer, acid etching, depth controlled uncovering, nickel-gold plating, testing and molding specifically include

[0040] Pattern transfer: Use the characteristics of photoresist to transfer the pattern to the copper surface, use medium roughening solution as pre-treatment to roughen the copper surface, the running speed is 2.5-3.2m / min, the micro-etching rate is 0.3-0.5μm, and the drying temperature is 80-90℃; the photoresist film sticking speed is 1.5±0.5m / min, and the film sticking pressure is 5±1kg / cm 2 , film pasting temperature 110±10℃, board output temperature 40-60℃, LDI machine automatic alignment exposure, and development after standing for 60 minutes.

[0041] Acid etching: Dry film / wet film covers the surface of the circuit pattern to prevent copper etching; other unwanted copper exposed on the substrate will be removed by chemical reaction to form the required circuit pattern. After the circuit pattern etching is completed, the dry film / wet film is removed with sodium hydroxide solution.

[0042] Depth control and cover removal: After the outer layer, mechanical depth control is performed and the cover is removed to remove the high-temperature protective film and expose the installation pad.

[0043] Electroless nickel and gold: A layer of nickel and gold is deposited on the copper surface through chemical reaction, giving it stable chemical and electrical properties. The thickness of electroless nickel is 120-200μ", and the thickness of electroless gold is 1-3μ" 。

[0044] Testing and molding: Testing is based on the voltage, on-resistance, and insulation resistance required by the customer as the set standards. When the measured on-resistance is greater than the set on-resistance, it is an open circuit; when the measured on-resistance is less than the set on-resistance, it is a short circuit; molding is to cut the panel-sized printed circuit board into the finished printed circuit board of the size required by the customer.

[0045] Compared with the prior art, the present invention slots the semi-cured sheet and the PMI material core board, mounts the PIN switch on the PTFE core board, and uses the low-flow semi-cured sheet for lamination, so that the PIN switch is protected and isolated by the PMI material; the mixed pressing of the PTFE material and the PMI material adopts the lamination mixed pressing process of the surrounding frame plate + the slotted cover plate, and the hole-in-hole design and processing method are adopted for the embedded PMI material PCB, so as to obtain the effect of the LEO antenna board with high reliability embedded PIN switch. DETAILED DESCRIPTION

[0046] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0047] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0048] It should also be understood that the terms used in this application specification are only for the purpose of describing specific embodiments and are not intended to limit the application. As used in this application specification and the appended claims, the singular forms "a", "an" and "the" are intended to include plural forms unless the context clearly indicates otherwise.

[0049] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0050] In view of the fact that the PIN switch is prone to cracking and crushing during the production process of the LEO antenna board with embedded PIN switches in the prior art, the semi-cured sheet needs to flow and solidify under a large pressure during the lamination of the high-frequency board. The present invention uses polymethacrylimide (PMI) material as a heat-resistant and shock-absorbing protective layer for the PIN switch. Polymethacrylimide (PMI) is a high molecular polymer with excellent thermal stability and mechanical properties. It has a wide range of operating temperatures, with a long-term operating temperature of up to 260°C, a short-term operating temperature of up to 400-450°C, and a starting decomposition temperature of generally around 500°C. In addition, PMI also has good dielectric properties, with a dielectric constant generally around 3.4 and a dielectric strength of 100-300kV / mm. PMI foam is a closed-cell cross-linked rigid foam plastic with excellent mechanical properties, high creep resistance, high heat deformation temperature and easy processing. According to the above characteristics of the PMI material, the present invention uses the PMI material as a protective layer core board to provide a high-frequency mixed pressure board with embedded PIN switches with stable performance and high reliability.

[0051] The embodiment of the present invention provides a method for manufacturing a LEO antenna board with an embedded PIN switch, comprising the following steps:

[0052] Make high-frequency core board of PTFE material, make high-frequency core board of PMI material; make slotted prepreg; mount PIN switch; mix and press PTFE material and PMI material; make PCB embedded with PMI material.

[0053] The production of high-frequency core boards made of PTFE materials specifically includes: cutting materials, pattern transfer, punching rivet holes, and sticking high-temperature tape.

[0054] Cutting: PTFE materials without copper and with thickness of 0.762mm, 0.508mm and 0.203mm are selected for cutting, namely L0102, L0506 and L0708. The size after cutting is 225mm*150mm; the fiber filaments left at the right angles of the board edge and the four sides of the board during cutting are removed by mechanical grinding; the board is placed in a vertical oven and baked at 150℃*2H to remove water vapor and organic volatiles.

[0055] Pattern transfer: For L0102, L0506, and L0708, film exposure is performed to make the PAD and target hole patterns. For L05, the surface mount PIN switch pattern is made. Acid etching is performed according to the designed pattern, and the film is etched cleanly and then retreated.

[0056] Punching rivet holes: Use OPE punching machine to automatically align by grabbing the target to punch out the rivet holes of L0102, L0506, and L0708 for riveting in the subsequent process.

[0057] High temperature tape: The entire surface of L07 is covered with high temperature tape, and the pattern for retaining the high temperature tape is cut out at the installation position by laser cutting.

[0058] The production of high-frequency core boards made of PMI materials specifically includes: cutting materials, drilling rivet holes, and slotting.

[0059] Cutting: Copper-free PMI material with a thickness of 0.508mm is selected for cutting, as L0304, and the size after cutting is 225mm*150mm; the edges and right angles left by the edges of the board and the four sides of the board during cutting are removed by mechanical grinding.

[0060] Punching rivet holes: Use OPE punching machine to punch out rivet holes of L0304 according to the predetermined size for riveting in the subsequent process.

[0061] Milling slot: Use CNC electric milling machine to locate the rivet hole of L0304, and mill the slot for the PIN switch on L0304. The slot size is 0.05-0.1mm larger than the PIN switch.

[0062] In this embodiment, an 8-layer circuit board is taken as an example for description, and the above L0102, L0506, L0708, and L0304 respectively represent different layers corresponding to the circuit board.

[0063] The process of making the slotted prepreg includes: cutting, drilling rivet holes and slotting.

[0064] Cutting: Use low-flow prepreg with a thickness of 0.092mm for cutting, and the size after cutting is 225mm*150mm.

[0065] Drilling rivet holes: Use a CNC drill to drill rivet holes with a diameter of 3.15mm on the prepreg for riveting in the subsequent process.

[0066] Slotting: Use a CNC electric milling machine to locate the rivet holes on the prepreg and mill out the slot required to embed the PIN switch. The slot size should be 0.05-0.1mm larger than the PIN switch.

[0067] The mounting of PIN switches specifically includes: printing solder paste, mounting of PIN switches, and reflow soldering.

[0068] Printing solder paste includes: making a steel mesh corresponding to the position of the mounted PIN switch and installing it on a solder paste printer, wherein the viscosity of the solder paste is detected to be 185±10pa.s; adding the solder paste to the steel mesh accordingly, and ensuring that the thickness of the solder paste does not exceed 25% of the height of the scraper blade of the solder paste printer; installing the steel mesh on the solder paste printer and positioning it, and then controlling the scraper on the solder paste printer to repeatedly move on the steel mesh so that the solder paste passes through the mesh holes on the steel mesh and covers the specific pads of the mounted PIN switch, thereby completing solder paste printing.

[0069] Mounting the PIN switch includes: mounting the PIN switch on the specific pad accordingly, so that the PIN switch is mounted on the specific pad accordingly through solder paste.

[0070] The reflow soldering includes: subjecting the core board after the PIN switch is mounted to the reflow soldering, wherein the reflow soldering includes preheating, constant temperature, reflow, and cooling treatment, wherein the preheating zone is 25-140°C, the time is 100S, and the heating slope is ≤1.2-2.5°C / S; the temperature of the constant temperature zone is controlled at 155-225°C, the time is 165S, and the heating slope is ≤1.2-2.6°C / S; the temperature of the reflow zone is controlled at 220-260°C, the time is 75S, and the heating slope is ≤1.0-2.6°C / S; the peak temperature of the cooling zone is controlled at Tmax-160°C, the peak temperature is 235-260°C, and the cooling slope is -1.0°C / S≤slope≤-2.6°C.

[0071] The PTFE material and PMI material are mixed and pressed, including:

[0072] Browning: Browning is performed on PFTE materials L0102, L0506, L0708 and PMI materials L0304 before lamination to clean and micro-roughen the board surface and enhance the bonding strength between the inner copper layer and the prepreg after lamination.

[0073] Pre-stacking: Fusing is done at the hot melt block positions of L0102, L0506, and L0708. After each layer of core board and prepreg are stacked in sequence, riveting is done at the four corner rivet holes with flower rivets.

[0074] Frame board preparation and use: 8 rectangular grooves of 235mm*160mm are milled in the middle of the FR4 substrate with a thickness of 2.7mm and a size of 650mm*500mm. 1mm board edges are retained on all sides and in the middle to place the pre-stacked mixed-pressed boards to ensure that the mixed-pressed boards of PTFE material and PMI material will not lose pressure or be over-pressed.

[0075] Preparation and use of the upper cover: The FR4 substrate with a thickness of 1.0 mm is milled with corresponding small rectangular grooves according to the positions of the embedded PIN switches. The upper cover and the frame are further riveted together to prevent the slotted core board with embedded PINs from collapsing during the pressing process.

[0076] Lamination: Use a hydraulic press, use composite materials for buffering, and use specific PFTE materials and PMI mixed pressure parameters for lamination; use the conversion process of the prepreg from B-stage to C-stage under high temperature and high pressure conditions to bond each layer of core board into one. The specific parameters are as follows:

[0077]

[0078] Target hole: according to the target hole pattern, punch the target holes required for drilling and alignment.

[0079] Gong edge: remove the burrs around the gong and grind the edges.

[0080] The production process of PCB embedded with PMI material includes mechanical drilling, resin plugging, secondary drilling, chemical copper and electroplating thickened copper.

[0081] The mechanical drilling and laminated boards use special parameters for high-frequency mixed-pressed boards containing PMI materials, and are enlarged by 0.8 mm based on the metallized hole requirements.

[0082] The resin plugging method plugs the holes formed by mechanical drilling with epoxy resin which is easy to process, and then grinds the resin after high temperature curing.

[0083] The secondary drilling is to drill holes at the positions of the original resin plug holes to form a hole-in-hole design structure.

[0084] The chemical copper and electroplated thickened copper utilize the principle of redox reaction to deposit colloidal palladium and copper on the secondary drilled holes. After the conduction is formed, the electroplated thickened copper reaches the required copper thickness.

[0085] The production process of embedded PMI material PCB also includes pattern transfer, acid etching, depth control uncovering, nickel-gold plating, testing and molding.

[0086] Pattern transfer: Use the characteristics of photoresist to transfer the pattern to the copper surface, use medium roughening solution as pre-treatment to roughen the copper surface, the running speed is 2.5-3.2m / min, the micro-etching rate is 0.3-0.5μm, and the drying temperature is 80-90℃; the photoresist film sticking speed is 1.5±0.5m / min, and the film sticking pressure is 5±1kg / cm 2 , film pasting temperature 110±10℃, board output temperature 40-60℃, LDI machine automatic alignment exposure, and development after standing for 60 minutes.

[0087] Acid etching: Dry film / wet film covers the surface of the circuit pattern to prevent copper etching; other unwanted copper exposed on the substrate will be removed by chemical reaction to form the required circuit pattern. After the circuit pattern etching is completed, the dry film / wet film is removed with sodium hydroxide solution.

[0088] Depth control and cover removal: After the outer layer, mechanical depth control is performed and the cover is removed to remove the high-temperature protective film and expose the installation pad.

[0089] Electroless nickel and gold: A layer of nickel and gold is deposited on the copper surface through chemical reaction, giving it stable chemical and electrical properties. The thickness of electroless nickel is 120-200μ", and the thickness of electroless gold is 1-3μ" 。

[0090] Testing and molding: Testing is based on the voltage, on-resistance, and insulation resistance required by the customer as the set standards. When the measured on-resistance is greater than the set on-resistance, it is an open circuit; when the measured on-resistance is less than the set on-resistance, it is a short circuit; molding is to cut the panel-sized printed circuit board into the finished printed circuit board of the size required by the customer.

[0091] In this embodiment, the PIN switch is mounted on the PTFE core board in advance by slotting the semi-cured sheet and the PMI material core board, and the low-flow semi-cured sheet is used for lamination, so that the PIN switch is protected and isolated by the PMI material around; the mixed-pressure board of the PMI material is debonded by plasma, and is thickened by electroplating after low-temperature sputtering coating to complete the hole metallization, thereby obtaining the effect of a high-reliability embedded PIN switch high-frequency board.

[0092] The specific implementation methods of the invention are described in detail above, but they are only examples, and the present invention is not limited to the specific implementation methods described above. For those skilled in the art, any equivalent modification or substitution of the invention is also within the scope of the present invention. Therefore, the equalization, modification, improvement, etc. made without departing from the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method for manufacturing a LEO antenna board with embedded PIN switch, characterized in that: Includes steps: Make high-frequency core boards made of PTFE materials, cut the PTFE material boards, transfer patterns, punch rivet holes, and apply high-temperature tape; Make high-frequency core boards made of PMI materials, cut the PMI material boards, punch rivet holes, and mill grooves; Make slotted prepregs, cut the prepregs, drill rivet holes, and slot them; Mounting PIN switches, including printing solder paste, mounting PIN switches, and reflow soldering; Mixing and pressing PTFE material and PMI material; Make PCB with embedded PMI material.

2. The method according to claim 1, characterized in that The method for making the high-frequency core board of PTFE material specifically comprises: Cutting: PTFE without copper and with three thicknesses of 0.762mm, 0.508mm and 0.203mm are selected for cutting, namely L0102, L0506 and L0708; Pattern transfer: For L0102, L0506, and L0708, film exposure is performed to make alignment PAD and target hole patterns. For L05, the surface mount PIN switch pattern is made. Acid etching is performed according to the designed pattern, and the film is etched cleanly. Punching rivet holes: Use OPE punching machine to automatically align by grabbing the target to punch out the rivet holes of L0102, L0506, and L0708 for riveting in the subsequent process. High temperature tape: The entire surface of L07 is covered with high temperature tape, and the pattern for retaining the high temperature tape is cut out at the installation position by laser cutting.

3. The method according to claim 2, characterized in that The method of making a high-frequency core board made of PMI material specifically includes: Cutting: Copper-free PMI material with a thickness of 0.508mm is selected for cutting, as L0304, and the size after cutting is 225mm*150mm; the edges and right angles left by the edges of the board and the four sides of the board during cutting are removed by mechanical grinding; Punching rivet holes: Use OPE punching machine to punch out rivet holes of L0304 according to the predetermined size for riveting in the subsequent process; Milling slot: Use CNC electric milling machine to locate the rivet hole of L0304, and mill the slot for the PIN switch on L0304. The slot size is 0.05-0.1mm larger than the PIN switch.

4. The method according to claim 3, characterized in that The method for making the grooved prepreg specifically comprises: Cutting: Use low-flow prepreg with a thickness of 0.092mm for cutting, and the size after cutting is 225mm*150mm; Drilling rivet holes: Use a CNC drill to drill rivet holes with a diameter of 3.15mm on the prepreg for riveting in the subsequent process; Slotting: Use a CNC electric milling machine to locate the rivet holes on the prepreg and mill out the slot required to embed the PIN switch. The slot size should be 0.05-0.1mm larger than the PIN switch.

5. The method according to claim 4, characterized in that The mounting PIN switch specifically comprises: Printing solder paste: Make a steel mesh corresponding to the position of the PIN switch to be mounted, and install it on a solder paste printer. The viscosity test value of the solder paste is 185±10pa.s; add the solder paste to the steel mesh accordingly, and ensure that the thickness of the solder paste does not exceed 25% of the height of the scraper blade of the solder paste printer; install the steel mesh on the solder paste printer and position it, and then control the scraper on the solder paste printer to repeatedly move on the steel mesh, so that the solder paste passes through the mesh holes on the steel mesh and covers the specific pads of the PIN switch to complete the solder paste printing; Mounting PIN switch: Mount the PIN switch on the specific pad accordingly, so that the PIN switch is mounted on the specific pad accordingly through solder paste; Reflow soldering: The core board after the PIN switch is mounted is subjected to reflow soldering, wherein the reflow soldering includes preheating, constant temperature, reflow and cooling treatment, the preheating zone is 25-140°C, the time is 100S, and the heating slope is ≤1.2-2.5°C / S; the temperature in the constant temperature zone is controlled at 155-225°C, the time is 165S, and the heating slope is ≤1.2-2.6°C / S; the temperature in the reflow zone is controlled at 220-260°C, the time is 75S, and the heating slope is ≤1.0-2.6°C / S; the peak temperature in the cooling zone is controlled at Tmax-160°C, the peak temperature is 235-260°C, and the cooling slope is -1.0°C / S≤slope≤-2.6°C.

6. The method according to claim 5, characterized in that The PTFE material and the PMI material are mixed and pressed, including Browning: Browning is performed on PFTE material L0102, L0506, L0708 and PMI material L0304 before lamination to clean and micro-roughen the board surface and enhance the bonding strength between the inner layer material and the prepreg after lamination; Pre-stacking: Fusing is done at the hot melt block positions of L0102, L0506, and L0708. After each layer of core board and prepreg are stacked in sequence, riveting is done at the four corner rivet holes with flower rivets; Frame board preparation and use: 8 rectangular grooves of 235mm*160mm are milled out in the middle of the FR4 substrate with a thickness of 2.7mm and a size of 650mm*500mm. 1mm board edges are reserved on all sides and in the middle to place the pre-stacked mixed-pressed boards to ensure that the mixed-pressed boards of PTFE material and PMI material will not lose pressure or be over-pressed; Preparation and use of the upper cover: The FR4 substrate with a thickness of 1.0 mm is milled with corresponding small rectangular grooves according to the positions of the embedded PIN switches. The upper cover and the frame are further riveted together to prevent the slotted core board with embedded PINs from collapsing during the pressing process. Lamination: Use a hydraulic press, use composite materials for buffering, and use specific PFTE materials and PMI mixed pressure parameters for lamination; use the conversion process of the prepreg from B-stage to C-stage under high temperature and high pressure conditions to bond each layer of the core board into one. The specific parameters include: Target hole: according to the target hole pattern, punch the target holes required for drilling and alignment; Gong edge: remove the burrs around the gong and grind the edges.

7. The method according to claim 6, characterized in that The method of manufacturing a PCB embedded with PMI material comprises: Hole processing: Mechanically drill holes on the laminated board using the special parameters for high-frequency mixed-pressed boards containing PMI materials, and increase the size by 0.8mm based on the requirements for metallized holes; plug the holes formed by mechanical drilling with epoxy resin that is easy to process, and grind the resin after high-temperature curing; drill holes at the locations of the original resin plug holes to form a hole-in-hole design structure; utilize the principle of redox reaction to deposit colloidal palladium and copper on the holes of the secondary drilling, and after the conduction is formed, electroplating thickened copper to achieve the required copper thickness; Pattern transfer: Use the characteristics of photoresist to transfer the pattern to the copper surface, use medium roughening solution as pre-treatment to roughen the copper surface, the running speed is 2.5-3.2m / min, the micro-etching rate is 0.3-0.5μm, and the drying temperature is 80-90℃; the photoresist film sticking speed is 1.5±0.5m / min, and the film sticking pressure is 5±1kg / cm 2 , film pasting temperature 110±10℃, board output temperature 40-60℃, LDI machine automatic alignment exposure, stand for 60 minutes before developing; Acid etching: Dry film / wet film covers the surface of the circuit pattern to prevent copper etching; other unwanted copper exposed on the substrate will be removed by chemical reaction to form the required circuit pattern. After the circuit pattern etching is completed, the dry film / wet film is removed with sodium hydroxide solution; Depth control and cover removal: After the outer layer, mechanical depth control is performed and the cover is removed to remove the high-temperature protective film and expose the installation pad. Electroless nickel and gold: A layer of nickel and gold is deposited on the copper surface through chemical reaction to give it stable chemical and electrical properties. The thickness of electroless nickel is 120-200μ", and the thickness of electroless gold is 1-3μ"; Testing and molding: Testing is based on the voltage, on-resistance, and insulation resistance required by the customer as the set standards. When the measured on-resistance is greater than the set on-resistance, it is an open circuit; when the measured on-resistance is less than the set on-resistance, it is a short circuit; molding is to cut the panel-sized printed circuit board into the finished printed circuit board of the size required by the customer.

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