CN108724900B - Preparation method of dry microwave composite dielectric plate - Google Patents
Preparation method of dry microwave composite dielectric plate Download PDFInfo
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Abstract
The invention relates to a preparation method of a dry-method microwave composite dielectric plate. The operation steps are as follows: (1) mixing and ball-milling a coupling agent, a hydrolysis solvent and micron ceramic powder; (2) uniformly mixing modified ceramic powder, polytetrafluoroethylene micro powder and a fluororesin modifier, drying and ball-milling; (3) molding the dry-process mixture through a mold to obtain a primary blank; (4) sintering to obtain a bar blank; (5) machining the bar blank into a smooth and uniform rectangular sheet with the thickness of less than 0.1 mm; (6) carrying out plasma activation treatment on the front surface and the back surface of the rectangular sheet; (7) overlapping and matching the activated sheet and the pure PTFE film to form a layer of basic unit material, and sequentially overlapping a plurality of layers of basic unit materials until the thickness of the basic unit materials reaches the design requirement to obtain the composite foundation plate; and respectively adding metal foils on the two side surfaces, and performing high-temperature vacuum pressing to obtain the PTFE-based microwave composite dielectric plate. The preparation process of the invention basically does not need waste gas collection and treatment, is green and energy-saving, and meets the requirement of environmental protection.
Description
Technical Field
The invention belongs to the technical field of dielectric plates for microwave electronics, and particularly relates to a preparation method of a PTFE (polytetrafluoroethylene) -based microwave composite dielectric plate.
Background
Polytetrafluoroethylene (PTFE) -based microwave composite dielectric plates are currently the lowest dielectric constant and lowest dielectric loss organic dielectric plate material system, and with the development trend of high frequency, high speed, miniaturization, integration and light weight, PTFE-based microwave composite dielectric plates are increasingly used in electronic equipment. And due to the excellent electrical property stability, weather resistance, temperature resistance and irradiation resistance of PTFE, the PTFE-based microwave composite dielectric plate can be exposed for ten years under any weather conditions without changing the original excellent property, so that the PTFE-based microwave composite dielectric plate is suitable for high-frequency-band severe installation conditions of an airborne machine, a satellite-borne machine, a missile-borne machine, a ship-borne machine and the like with the wave band of 300 MHz-40 GHz, and is widely used in active model equipment and pre-ground products.
The main preparation method of the PTFE-based microwave composite dielectric slab at home and abroad is a wet impregnation process, namely a method for manufacturing glass fiber varnished cloth by impregnating glass fiber cloth with inorganic filler modified PTFE emulsion and then superposing and hot-pressing the glass fiber varnished cloth, wherein the glass fiber cloth is used as a rigid support source, so that the thermal expansion coefficient and the dimensional stability of an X, Y axis can be effectively regulated and controlled, the processability is improved, but the thermal expansion coefficient of a Z axis is increased, the anisotropy of the performance is generated, and the manufacture of a multilayer microstrip board and the reliability of a product in a later period are not facilitated. The dipping method mainly uses a vertical dipping machine, glue solutions with certain viscosity and different solid contents are added into a glue tank, and the glass fiber cloth is repeatedly dipped into the glue solution and dried by an oven for a plurality of times through the dipping machine to finally prepare the varnished cloth with certain thickness. After being overlapped, the multiple layers of varnished cloth are heated, pressurized and melted and formed in a hot press at about 380 ℃, and finally the uniform microwave composite dielectric plate is formed. The method can be used for continuous mass production, but the procedures of pretreatment of raw materials, mixing and preparation of glue solution, discharge of waste glue solution and the like all generate a large amount of wastewater which can be normally discharged after secondary treatment, a large amount of waste gas is generated in the drying process of the impregnator, and complex treatment devices are needed for collecting and treating the waste gas which is repeatedly dried. With the improvement of the environmental protection degree, the process has to be provided with a complicated flow to meet the urban environmental protection requirement, and the manufacturing cost is high.
Disclosure of Invention
The invention provides a preparation method of a dry-method microwave composite dielectric plate, aiming at realizing simple, convenient, efficient, green, clean and environment-friendly production of the microwave composite dielectric plate with excellent and stable performance.
The operation steps of the dry method microwave composite dielectric plate are as follows:
(1) pretreatment of raw materials
Adding 0.08-1 part of hydrolysis solvent into 0.1-4 parts of coupling agent, and hydrolyzing to obtain modified coupling agent; mixing the modified coupling agent and 10-400 parts of micron ceramic powder, and carrying out ball milling to obtain modified ceramic powder;
(2) dry mixing
Uniformly mixing modified ceramic powder, 100 parts of polytetrafluoroethylene micro Powder (PTFE) and 1-10 parts of fluororesin modifier, drying and ball-milling to obtain a dry-process mixture;
(3) die pressing
Loading the dry-process mixture into a metal female die, closing the die, carrying out die pressing, and demoulding to obtain a primary blank; according to the powder formula composition, the volume ratio of the dry method mixture in the metal female die to the primary blank is 3-6: 1;
(4) sintering
Sintering the primary blank in a sintering furnace to melt PTFE in the primary blank, so that ceramic powder is uniformly dispersed in a PTFE matrix rod blank material to obtain a rod blank;
(5) machining
Machining the bar blank into a smooth and uniform rectangular sheet with consistent thickness, wherein the thickness of the rectangular sheet is less than 0.1 mm;
(6) post-treatment
Carrying out plasma activation treatment on the front surface and the back surface of the rectangular sheet to obtain a post-treatment sheet;
(7) lamination matched high temperature lamination
Overlapping and matching the post-processing sheet and the pure PTFE film to form a layer of basic unit material, and sequentially overlapping multiple layers of basic unit materials until the thickness of the basic unit materials reaches the design requirement to obtain the composite foundation plate; and respectively adding metal foils on two side surfaces of the composite base plate, and performing high-temperature vacuum pressing to obtain the PTFE-based microwave composite dielectric plate.
The technical scheme for further limiting is as follows:
the coupling agent is more than one of silane coupling agent, titanium coupling agent and zirconium coupling agent;
the hydrolysis solvent is more than one of water, dichloromethane, ethanol, acetone, propylene glycol monomethyl ether and xylene;
the fluororesin modifier is more than one of fluorinated ethylene propylene, perfluoroalkoxy resin, ethylene-tetrafluoroethylene copolymer and ethylene-chlorotrifluoroethylene copolymer;
the micron ceramic powder is more than one of crystalline silicon dioxide, fused silicon dioxide, spherical silicon dioxide, rutile titanium dioxide, anatase titanium dioxide, alumina, neodymium aluminate, calcium titanate, barium titanate and other perovskite structure ceramic fillers, boron nitride, aluminum nitride and silicon carbide; the particle size of the micron ceramic powder is 0.1-30 μm;
the particle size of the polytetrafluoroethylene micro powder is 5-50 mu m.
Preferably, the particle size of the micron ceramic powder is 10.0-15.0 microns, and the particle size of the polytetrafluoroethylene micro powder is 10.0-15.0 microns, so that the most effective configuration parameters are achieved.
In the step (1), ball milling conditions are as follows: ball milling is carried out for 1-2 h at the temperature of 60-90 ℃.
In the step (2), the mixed material is dried for 3 hours at the temperature of 120 ℃, and cooled to room temperature; and then adding the mixture into a ball mill, and carrying out ball milling for 2-4 h at the temperature of 30-60 ℃.
In the step (3), the mould pressing process conditions are as follows: the pressure is increased to 10-30 Mpa within 0.5h, and the pressure is maintained for 0.5-2 h.
In the step (4), the sintering process conditions are as follows: slowly heating to 370-390 ℃ at the heating rate of 15-40 ℃/h, and sintering for 2-4 h; the temperature reduction rate of sintering is 15-60 ℃/h.
In the step (5), the mechanical processing is turning, and the turning processing conditions are as follows: the rotation speed is 20-50 rpm, and the turning thickness is 0.025-0.1 mm.
In the step (6), the plasma activation treatment conditions are as follows: the volume ratio of nitrogen to hydrogen is 1: 0.4-0.8, the flow rate is 800-1200 ml/min, the power is 1600-2200W, and the time is 35-70 min.
In the step (7), the layer of basic unit material consists of a post-processing sheet and a layer of pure PTFE film, or consists of a post-processing sheet and two layers of pure PTFE films, or consists of two post-processing sheets and a layer of pure PTFE film, or consists of two post-processing sheets and two layers of pure PTFE films;
the metal foil is one of copper alloy foil, aluminum alloy foil and nickel alloy foil; vacuum lamination conditions of the high-temperature laminator: the peak temperature of the pressing is 350-390 ℃, and the pressing pressure is 25-100 Kg/cm2The pressing time is 2-10 h.
The beneficial technical effects of the invention are embodied in the following aspects:
(1) the core plate of the PTFE-based microwave composite dielectric plate prepared by the invention is a homogeneous system, the ceramic powder is uniformly distributed in the PTFE matrix, the expansion of the Z axis is greatly reduced (the CTE is 220ppm/oC or even higher), the isotropy is improved (the CTE of X, Y axis is basically consistent), the thermal expansion of the material is close to that of copper (the CTE is 17ppm/oC), the reliability of the metallized hole is obviously improved, the bonding strength is increased, and the use requirements of microwave frequency band type equipment in the existing satellite-borne vacuum low-temperature environment, ship-borne high-humidity high-salt environment, plateau high ultraviolet high temperature difference environment and the like can be met.
(2) The PTFE-based microwave composite dielectric plate has a simple formula, does not need to add other solvents in the preparation process, does not need wet mixing and transportation, does not need to dry glue solution, does not need pipeline circulation, hardly generates waste water, and avoids sewage collection, treatment and discharge of an impregnation process. Only a small amount of gas is generated in the sintering and hot pressing processes in the preparation process, and waste gas collection and treatment are basically not needed, so that the preparation method is green and energy-saving, and meets the requirement of environmental protection.
(3) The preparation process equipment of the PTFE-based microwave composite dielectric plate has small occupied area, only needs a ball mill, a sintering furnace and a turning system, occupies much smaller area than a dipping system, is mature in equipment manufacture, simple and rapid in process route, saves 50% of preparation period compared with the traditional dipping, and is easy to control conditions; the preparation cost is low, the manpower and the financial resources are saved, and the product quality is stable.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the detailed description and specific examples, while indicating the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.
Example 1
The materials used in this example are illustrated below:
0.01Kg of coupling agent F8261, 0.008Kg of hydrolysis solvent xylene, 10Kg of PTFE micropowder, 1Kg of fluorinated ethylene propylene (fluororesin modifier), 1Kg of fused silica (micron ceramic powder). D50 ═ 5 μm for PTFE micropowder; d50 of micron ceramic powder is 0.1 μm; d50 indicates the corresponding particle size at which the cumulative percent particle size distribution of the sample reached 50%.
The dry method microwave composite dielectric plate comprises the following specific preparation operation steps:
(1) pretreatment of raw materials
0.008Kg of hydrolysis solvent xylene is added into 0.01Kg of coupling agent F8261, and the modified coupling agent is obtained by hydrolysis; adding the modified coupling agent and 1Kg of fused silica into a ball mill, and carrying out ball milling for 2h at the temperature of 60 ℃ to obtain the modified ceramic powder.
(2) Dry mixing
Uniformly mixing the modified ceramic powder prepared in the step (1), 1Kg of PTFE micro powder and 1Kg of fluorinated ethylene propylene, drying for 3h at the temperature of 120 ℃, and cooling to room temperature; and adding the mixture into a ball mill, performing ball milling for 4 hours at the temperature of 30 ℃, taking out, and cooling to room temperature to obtain a dry-process mixture.
(3) Die pressing
Uniformly placing all the dry-process mixture prepared in the step (2) into a metal female die, and closing the die after the metal female die is filled with the mixture; under the condition of room temperature, increasing the pressure to 10Mpa within 0.5h, and maintaining the pressure for 2 h; demolding to obtain a primary blank; the volume ratio of the dry-process mixture in the metal female die to the primary blank is 3: 1.
(4) Sintering
Putting the primary blank into a sintering furnace, slowly heating to 370 ℃ at a heating rate of 15 ℃/h, sintering for 2.0h until PTFE is molten to form ceramic powder which is uniformly dispersed in a bar blank material; the cooling rate after sintering is 15 ℃/h until the temperature reaches the room temperature, and a bar blank is obtained.
(5) Machining
The mechanical processing is turning, the bar blank is cut into smooth and uniform core plate coiled materials with consistent thickness by a lathe, the turning speed is 20rpm, and the turning thickness is 0.025 mm; and cutting the rolled core plate into a rectangular sheet, wherein the turning thickness is the thickness of the rectangular sheet.
(6) Post-treatment
Carrying out plasma activation treatment on the front surface and the back surface of the rectangular sheet: the volume ratio of nitrogen to hydrogen is 1: 0.4, the flow rate is 800ml/min, the power is 1600W, the processing time is 35min, and the post-processing sheet is obtained.
(7) Lamination matched high temperature lamination
A piece of post-treated sheet and a layer of pure PTFE film, which is a uniform PTFE lathed film with a thickness of 0.013mm, were superposed and fitted as a layer of basic unit material. Sequentially overlapping 9 layers of basic unit materials until the thickness of the basic unit materials reaches 0.3mm of the design requirement, and obtaining the composite foundation plate; metal foils are respectively arranged on two side surfaces of the composite foundation plate, and the metal foils are copper foils;
placing the composite foundation plate with copper foils on two side surfacesPutting the mixture into a high-temperature laminating machine for vacuum lamination, wherein the process conditions of the vacuum lamination are as follows: the peak pressing temperature is 350 ℃ and the pressure is 25Kg/cm2And the time is 2h, and the microwave composite dielectric plate is obtained. The dielectric constant and the dielectric loss are tested according to an IPC-TM-6502.5.5.5 clamped microstrip line test method, the linear thermal expansion coefficient of a X, Y, Z axis is measured according to IPC-TM-6502.4.41, the stripping strength of the microwave composite dielectric plate is measured according to IPC TM-6502.4.8, and the technical index result of the microwave composite dielectric plate is as follows: the dielectric constant Dk was 2.21, the dielectric loss Df was 0.0013, the thermal expansion coefficients of the X-axis, Y-axis and Z-axis were 41 ppm/DEG C, 58 ppm/DEG C, 197 ppm/DEG C, and the peel strength was 3.0N/mm, respectively.
Example 2
The materials used in this example are illustrated below:
0.1Kg of coupling agent F8261, 0.1Kg of coupling agent AN, 0.08Kg of hydrolysis solvent dichloromethane, 50Kg of PTFE micropowder, 5Kg of perfluoroalkoxy resin (fluororesin modifier), 40Kg of fused silica (micron ceramic powder), 60Kg of alumina (micron ceramic powder).
D50 ═ 5 μm for PTFE micropowder; d50 of micron ceramic powder is 0.1 μm; d50 indicates the corresponding particle size at which the cumulative percent particle size distribution of the sample reached 50%.
The dry method microwave composite dielectric plate comprises the following specific preparation operation steps:
(1) pretreatment of raw materials
0.1Kg of coupling agent F8261 and 0.1Kg of coupling agent AN are uniformly mixed to obtain a mixed coupling agent; adding 0.08Kg of hydrolysis solvent methylene dichloride into the mixed coupling agent, and hydrolyzing to obtain a modified coupling agent; adding the modified coupling agent, 40Kg of fused silica and 60Kg of alumina into a ball mill, and ball-milling for 1h at 90 ℃ to obtain the modified ceramic powder.
(2) Dry mixing
Uniformly mixing the modified ceramic powder prepared in the step (1), 50Kg of PTFE micro powder and 5Kg of perfluoroalkoxy resin, drying for 3h at the temperature of 120 ℃, and cooling to room temperature; and adding the mixture into a ball mill, performing ball milling for 2 hours at the temperature of 60 ℃, taking out, and cooling to room temperature to obtain a dry-process mixture.
(3) Die pressing
Uniformly placing all the dry-process mixture prepared in the step (2) into a metal female die, and closing the die after the metal female die is filled with the mixture; under the condition of room temperature, increasing the pressure to 30Mpa within 0.5h, and maintaining the pressure for 0.5 h; demolding to obtain a primary blank; the volume ratio of the dry-process mixture in the metal female die to the primary blank is 4: 1.
(4) Sintering
Putting the primary blank into a sintering furnace, slowly heating to 390 ℃ at the heating rate of 40 ℃/h, sintering for 2.0h until PTFE is molten to form ceramic powder which is uniformly dispersed in the bar blank material; the cooling rate after sintering is 60 ℃/h till the room temperature, and a bar blank is obtained.
(5) Machining
The mechanical processing is turning, the bar blank is cut into a smooth and uniform core plate coiled material with consistent thickness by a lathe, the turning speed is 50rpm, and the turning thickness is 0.1 mm; and cutting the rolled core plate into a rectangular sheet, wherein the turning thickness is the thickness of the rectangular sheet.
(6) Post-treatment
Carrying out plasma activation treatment on the front surface and the back surface of the rectangular sheet: the volume ratio of nitrogen to hydrogen is 1: 0.8, the flow rate is 1200ml/min, the power is 2200W, the processing time is 70min, and the post-processing sheet is obtained.
(7) Lamination matched high temperature lamination
A piece of post-processing sheet material and a layer of pure PTFE film are overlapped and matched to be used as a layer of basic unit material, and the pure PTFE film is a homogeneous PTFE turning film with the thickness of 0.02 mm. Sequentially overlapping 5 layers of basic unit materials until the thickness of the basic unit materials reaches 0.55mm of the design requirement, and obtaining the composite foundation plate; metal foils are respectively arranged on two side surfaces of the composite foundation plate, and the metal foils are copper foils;
putting the composite base plate with the copper foils on the two side surfaces into a high-temperature laminating machine for vacuum lamination, wherein the vacuum lamination process conditions are as follows: the peak temperature of the pressing is 390 ℃ and the pressure is 100Kg/cm2And the time is 10h, and the microwave composite dielectric plate is obtained. Testing dielectric constant and dielectric loss according to IPC-TM-6502.5.5.5 clamped microstrip line test method, determining X, Y, Z axis linear thermal expansion coefficient according to IPC-TM-6502.4.41, determining microwave composite dielectric plate peeling strength according to IPC-6502.4.8,the technical index result of the microwave composite dielectric plate of the embodiment is as follows: the dielectric constant Dk is 6.24, the dielectric loss Df is 0.0024, the thermal expansion coefficients of the X-axis, the Y-axis and the Z-axis are respectively 15 ppm/DEG C, 16 ppm/DEG C and 33 ppm/DEG C, and the anti-stripping strength is 1.9N/mm.
Example 3
The materials used in this example are illustrated below:
0.08Kg of coupling agent AN, 0.05Kg of ethanol as a hydrolysis solvent, 10Kg of PTFE micropowder, 1Kg of ethylene-tetrafluoroethylene copolymer (fluororesin modifier), 30Kg of rutile silica (micron ceramic powder).
D50 ═ 5 μm for PTFE micropowder; d50 of micron ceramic powder is 0.1 μm; d50 indicates the corresponding particle size at which the cumulative percent particle size distribution of the sample reached 50%.
The dry method microwave composite dielectric plate comprises the following specific preparation operation steps:
(1) pretreatment of raw materials
Adding 0.05Kg of ethanol as a hydrolysis solvent into 0.08Kg of coupling agent AN, and hydrolyzing to obtain a modified coupling agent; adding the modified coupling agent and 30Kg of rutile silicon dioxide into a ball mill, and carrying out ball milling for 2h at the temperature of 80 ℃ to obtain the modified ceramic powder.
(2) Dry mixing
Uniformly mixing the modified ceramic powder prepared in the step (1), 10Kg of PTFE micro powder and 1Kg of ethylene-tetrafluoroethylene copolymer, drying for 3h at the temperature of 120 ℃, and cooling to room temperature; then adding the mixture into a ball mill, carrying out ball milling for 3.5h at the temperature of 50 ℃, taking out the mixture, and cooling the mixture to room temperature to obtain a dry-process mixture.
(3) Die pressing
Uniformly placing all the dry-process mixture prepared in the step (2) into a metal female die, and closing the die after the metal female die is filled with the mixture; under the condition of room temperature, increasing the pressure to 25Mpa within 0.5h, and maintaining the pressure for 3 h; demolding to obtain a primary blank; the volume ratio of the dry-process mixture in the metal female die to the primary blank is 5: 1.
(4) Sintering
Putting the primary blank into a sintering furnace, slowly heating to 390 ℃ at the heating rate of 40 ℃/h, sintering for 2.0h until PTFE is molten to form ceramic powder which is uniformly dispersed in the bar blank material; the cooling rate after sintering is 60 ℃/h till the room temperature, and a bar blank is obtained.
(5) Machining
The mechanical processing is turning, the bar blank is cut into smooth and uniform core plate coiled materials with consistent thickness by a lathe, the turning speed is 40rpm, and the turning thickness is 0.05 mm; and cutting the rolled core plate into a rectangular sheet, wherein the turning thickness is the thickness of the rectangular sheet.
(6) Post-treatment
Carrying out plasma activation treatment on the front surface and the back surface of the rectangular sheet: the volume ratio of nitrogen to hydrogen is 1: 0.8, the flow rate is 1100ml/min, the power is 2000W, the processing time is 60min, and the post-processing sheet is obtained.
(7) Lamination matched high temperature lamination
A piece of post-processing sheet material and a layer of pure PTFE film are overlapped and matched to be used as a layer of basic unit material, and the pure PTFE film is a homogeneous PTFE turning film with the thickness of 0.02 mm. Sequentially overlapping 15 layers of basic unit materials until the thickness of the basic unit materials reaches 1mm of the design requirement, and obtaining the composite foundation plate; metal foils are respectively arranged on two side surfaces of the composite foundation plate, and the metal foils are copper foils;
putting the composite base plate with the copper foils on the two side surfaces into a high-temperature laminating machine for vacuum lamination, wherein the vacuum lamination process conditions are as follows: the peak pressing temperature is 370 ℃ and the pressure is 100Kg/cm2And the time is 10h, and the microwave composite dielectric plate is obtained. The dielectric constant and the dielectric loss are tested according to an IPC-TM-6502.5.5.5 clamped microstrip line test method, the linear thermal expansion coefficient of a X, Y, Z axis is measured according to IPC-TM-6502.4.41, the stripping strength of the microwave composite dielectric plate is measured according to IPC TM-6502.4.8, and the technical index result of the microwave composite dielectric plate is as follows: dielectric constant Dk is 10.1, dielectric loss Df is 0.0023, X-axis Y-axis Z-axis thermal expansion coefficient is 12 ppm/DEG C, 11 ppm/DEG C, 29 ppm/DEG C, and anti-stripping strength is 2.2N/mm.
Example 4
The materials used in this example are illustrated below:
0.16Kg of coupling agent Z-6124, 0.16Kg of coupling agent Z-6030, 0.9Kg of acetone as a hydrolysis solvent, 200Kg of PTFE micropowder, 10Kg of fluorinated ethylene propylene (fluororesin modifier), 200Kg of fused silica (micron ceramic powder), 400Kg of rutile silica (micron ceramic powder), and 200Kg of alumina (micron ceramic powder).
D50 ═ 5 μm for PTFE micropowder; d50 of micron ceramic powder is 0.1 μm; d50 indicates the corresponding particle size at which the cumulative percent particle size distribution of the sample reached 50%.
The dry method microwave composite dielectric plate comprises the following specific preparation operation steps:
(1) pretreatment of raw materials
Uniformly mixing 0.16Kg of coupling agent Z-6124 and 0.16Kg of coupling agent Z-6030 to obtain a mixed coupling agent; adding 0.9Kg of hydrolysis solvent acetone into the mixed coupling agent, and hydrolyzing to obtain a modified coupling agent; adding the modified coupling agent, 200Kg of fused silica, 400Kg of rutile silica and 200Kg of alumina into a ball mill, and ball-milling for 2 hours at the temperature of 90 ℃ to obtain modified ceramic powder;
(2) dry mixing
Uniformly mixing the modified ceramic powder prepared in the step (1), 200Kg of PTFE micro powder and 10Kg of fluorinated ethylene propylene, drying for 3h at the temperature of 120 ℃, and cooling to room temperature; and adding the mixture into a ball mill, performing ball milling for 4 hours at the temperature of 60 ℃, taking out, and cooling to room temperature to obtain a dry-process mixture.
(3) Die pressing
Uniformly placing all the dry-process mixture prepared in the step (2) into a metal female die, and closing the die after the metal female die is filled with the mixture; under the condition of room temperature, increasing the pressure to 30Mpa within 0.5h, and maintaining the pressure for 2 h; demolding to obtain a primary blank; the volume ratio of the dry-process mixture in the metal female die to the primary blank is 6: 1.
(4) Sintering
Putting the primary blank into a sintering furnace, slowly heating to 380 ℃ at the heating rate of 30 ℃/h, sintering for 2.0h until PTFE is molten to form ceramic powder which is uniformly dispersed in the bar blank material; the cooling rate after sintering is 60 ℃/h till the room temperature, and a bar blank is obtained.
(5) Machining
The mechanical processing is turning, the bar blank is cut into a smooth and uniform core plate coiled material with consistent thickness by a lathe, the turning speed is 50rpm, and the turning thickness is 0.1 mm; and cutting the rolled core plate into a rectangular sheet, wherein the turning thickness is the thickness of the rectangular sheet.
(6) Post-treatment
Carrying out plasma activation treatment on the front surface and the back surface of the rectangular sheet: the volume ratio of nitrogen to hydrogen is 1: 0.8, the flow rate is 1200ml/min, the power is 2200W, the processing time is 70min, and the post-processing sheet is obtained.
(7) Lamination matched high temperature lamination
A piece of post-treated sheet and a layer of pure PTFE film, which is a uniform PTFE lathed film with a thickness of 0.013mm, were superposed and fitted as a layer of basic unit material. Sequentially overlapping 10 layers of basic unit materials until the thickness of the basic unit materials reaches 1.58mm of the design requirement, and obtaining the composite foundation plate; metal foils are respectively arranged on two side surfaces of the composite foundation plate, and the metal foils are copper foils;
putting the composite base plate with the copper foils on the two side surfaces into a high-temperature laminating machine for vacuum lamination, wherein the vacuum lamination process conditions are as follows: the peak temperature of the pressing is 385 ℃ and the pressure is 100Kg/cm2And the time is 5h, and the microwave composite dielectric plate is obtained. The dielectric constant and the dielectric loss are tested according to an IPC-TM-6502.5.5.5 clamped microstrip line test method, the linear thermal expansion coefficient of a X, Y, Z axis is measured according to IPC-TM-6502.4.41, the stripping strength of the microwave composite dielectric plate is measured according to IPC TM-6502.4.8, and the technical index result of the microwave composite dielectric plate is as follows: the dielectric constant Dk is 2.99, the dielectric loss Df is 0.0015, the thermal expansion coefficients of the X-axis, Y-axis and Z-axis are 17 ppm/DEG C, 18 ppm/DEG C and 24 ppm/DEG C respectively, and the anti-stripping strength is 2.1N/mm.
With respect to examples 5 to 8
The amounts of the respective raw materials added in examples 5 to 8 are shown in Table 1, the specific production procedure in example 5 was the same as in example 1, the specific production procedure in example 6 was the same as in example 2, the specific production procedure in example 7 was the same as in example 3, and the specific production procedure in example 8 was the same as in example 4. The microwave composite dielectric board obtained in example 4 was measured for dielectric constant and dielectric loss according to the IPC-TM-6502.5.5.5 clamped microstrip line test method, for linear thermal expansion coefficient of X, Y, Z axis according to IPC-TM-6502.4.41, and for peel strength according to IPC TM-6502.4.8, and the results are shown in table 2.
As can be seen from table 2, the core plate of the PTFE-based microwave composite dielectric plate prepared in the present invention is a homogeneous system, and the ceramic powder is uniformly distributed in the PTFE matrix, thereby greatly reducing the expansion of the Z axis, improving the isotropy, making the thermal expansion of the material close to that of copper, significantly improving the reliability of the metallized hole, increasing the bonding strength, improving the disadvantages of insufficient PTFE rigidity and easy deformation after long-term use, and simultaneously obtaining a microwave composite dielectric plate with any dielectric constant of high, medium, and low by compounding multiple ceramic powders. The process method has the advantages of simple and convenient process, high efficiency, greenness and cleanness, and provides a novel manufacturing process for the microwave composite dielectric plate applied to the fields of communication, medical treatment, military, automobiles, computers, instruments and the like.
TABLE 1 EXAMPLES 1-8 various raw materials addition levels
Table 2 comparison of test results for products of examples 1-8
Examples 1-8 cover a typical microwave dielectric sheet product with high PTFE content and high filler content. The very high PTFE content of example 1, with a high Z-axis coefficient of thermal expansion, has been a major limiting factor in the inability to achieve multi-layer lamination and highly reliable metallized holes. Compared with the existing foreign products, the dielectric constant of the product in the example 1 is equivalent, and the thermal expansion coefficient of the Z axis is reduced by about 20 percent. In other examples, the Z-axis thermal expansion coefficient is reduced by about 30% compared with the domestic existing products.
It will be readily understood by those skilled in the art that the foregoing is merely a preferred embodiment of the present invention and is not intended to limit the invention, wherein the fluororesin modifier is not limited to polyperfluoroethylpropylene, perfluoroalkoxy resins, ethylene-tetrafluoroethylene copolymers, ethylene-chlorotrifluoroethylene copolymers, and combinations thereof with the first three, are equally suitable for use in the present invention; the micron ceramic powder is not limited to fused silica, rutile titanium dioxide, neodymium aluminate, barium titanate and alumina, and spherical silica, anatase titanium dioxide, crystalline silica, calcium titanate, other perovskite structure ceramic fillers, boron nitride, aluminum nitride, silicon carbide and the like are all suitable for the invention; the silane coupling agent is not limited to F8261, AN, Z-6124, Z-6030, Lica12 and LZ-44, and KH550, KH560, KH570, Z-6020, Z-6070, Z-6040, NDZ-401 and NZ12 and the like are equally applicable to the present invention. Furthermore, any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (4)
1. A preparation method of a dry-method microwave composite dielectric plate is characterized by comprising the following operation steps:
(1) pretreatment of raw materials
Adding 0.08-1 part of hydrolysis solvent into 0.1-4 parts of coupling agent, and hydrolyzing to obtain modified coupling agent; mixing and ball-milling the modified coupling agent and 10-400 parts of micron ceramic powder, wherein the ball-milling conditions are as follows: ball milling for 1-2 h at the temperature of 60-90 ℃ to obtain modified ceramic powder;
the coupling agent is more than one of silane coupling agent, titanium coupling agent and zirconium coupling agent;
the hydrolysis solvent is more than one of water, dichloromethane, ethanol, acetone, propylene glycol monomethyl ether and xylene;
the micron ceramic powder is more than one of crystalline silicon dioxide, fused silicon dioxide, spherical silicon dioxide, rutile titanium dioxide, anatase titanium dioxide, alumina, neodymium aluminate, calcium titanate, barium titanate and other perovskite structure ceramic fillers, boron nitride, aluminum nitride and silicon carbide;
(2) dry mixing
Uniformly mixing modified ceramic powder, 100 parts of polytetrafluoroethylene micro Powder (PTFE) and 1-10 parts of fluororesin modifier, baking for 3 hours at the temperature of 120 ℃, and cooling to room temperature; adding the mixture into a ball mill, and performing ball milling for 2-4 hours at the temperature of 30-60 ℃ to obtain a dry-process mixture;
the fluororesin modifier is more than one of fluorinated ethylene propylene, perfluoroalkoxy resin, ethylene-tetrafluoroethylene copolymer and ethylene-chlorotrifluoroethylene copolymer;
(3) die pressing
Loading the dry-process mixture into a metal female die, closing the die, carrying out die pressing, and demoulding to obtain a primary blank; according to the powder formula composition, the volume ratio of the metal female die dry method mixture to the primary blank is (3-6): 1;
the molding process conditions are as follows: boosting the pressure to 10-30 Mpa within 0.5h, and maintaining the pressure for 0.5-2 h;
(4) sintering
Sintering the primary blank in a sintering furnace to melt PTFE in the primary blank, so that the ceramic powder is uniformly dispersed in a PTFE matrix rod blank material to obtain a rod blank;
the sintering process conditions are as follows: slowly heating to 370-390 ℃ at the heating rate of 15-40 ℃/h, and sintering for 2-4 h; the temperature reduction rate of sintering is 15-60 ℃/h;
(5) machining
Machining the bar blank into a smooth and uniform rectangular sheet with consistent thickness, wherein the thickness of the rectangular sheet is less than 0.1 mm;
the mechanical processing is turning;
(6) post-treatment
Carrying out plasma activation treatment on the front surface and the back surface of the rectangular sheet to obtain a post-treatment sheet;
plasma activation treatment conditions: the volume ratio of nitrogen to hydrogen is 1: 0.4-0.8, the flow rate is 800-1200 ml/min, the power is 1600-2200W, and the time is 35-70 min;
(7) lamination matched high temperature lamination
Overlapping and matching the post-processing sheet and the pure PTFE film to form a layer of basic unit material, and sequentially overlapping multiple layers of basic unit materials until the thickness of the basic unit materials reaches the design requirement to obtain the composite foundation plate; respectively adding metal foils on two side surfaces of the composite base plate, and performing high-temperature vacuum pressing to obtain a PTFE-based microwave composite dielectric plate;
the metal foil is one of copper alloy foil, aluminum alloy foil and nickel alloy foil; vacuum lamination conditions of the high-temperature laminator: the peak temperature of the pressing is 350-390 ℃, and the pressing pressure is 25-100 Kg/cm2The pressing time is 2-10 h.
2. The method for preparing a dry microwave composite dielectric plate according to claim 1, wherein the method comprises the following steps:
the particle size of the micron ceramic powder is 0.1-30 μm;
the particle size of the polytetrafluoroethylene micro powder is 5-50 mu m.
3. The method for preparing a dry microwave composite dielectric plate according to claim 1, wherein the method comprises the following steps: in the step (5), the turning conditions are as follows: the rotation speed is 20-50 rpm, and the turning thickness is 0.025-0.1 mm.
4. The method for preparing a dry microwave composite dielectric plate according to claim 1, wherein the method comprises the following steps: in the step (7), the layer of basic unit material consists of one post-processing sheet and one layer of pure PTFE film, or consists of one post-processing sheet and two layers of pure PTFE films, or consists of two post-processing sheets and one layer of pure PTFE film, or consists of two post-processing sheets and two layers of pure PTFE films.
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| CN110039851B (en) * | 2019-04-19 | 2021-04-09 | 中国电子科技集团公司第四十六研究所 | Preparation method of polytetrafluoroethylene copper-clad plate |
| CN110815683A (en) * | 2019-10-18 | 2020-02-21 | 温州大学 | PTFE composite grid plate |
| CN110744839A (en) * | 2019-11-01 | 2020-02-04 | 中国电子科技集团公司第四十六研究所 | Process for preparing composite dielectric plate based on low dielectric constant turning film |
| CN111540688B (en) * | 2020-05-12 | 2021-09-03 | 中国电子科技集团公司第三十八研究所 | Preparation method for metalizing side wall of LTCC substrate and LTCC substrate |
| CN111823619A (en) * | 2020-06-24 | 2020-10-27 | 腾辉电子（苏州）有限公司 | Preparation method of PTFE composite material film, PTFE film and copper-clad plate using PTFE film |
| CN111976164A (en) * | 2020-06-24 | 2020-11-24 | 腾辉电子（苏州）有限公司 | Preparation method of polytetrafluoroethylene-based metal substrate and metal substrate |
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