Preparation method of low dielectric and low expansion polytetrafluoroethylene high-frequency copper clad plate

Abstract

The application discloses a kind of preparation methods of low dielectric low expansion polytetrafluoroethylene high-frequency copper-clad plate, step 1 preparation glue A and glue B;Step 2, glue A and glue B are impregnated coating, air dry, low-temperature baking and high-temperature baking after being coated with glass fiber cloth on high temperature gluing machine, and the medium layer is prepared, the medium layer includes the following components: fluorine resin volume percentage 12%-25%, silane coupling agent volume percentage 3%-6%, inorganic filler volume percentage 60-65%, reinforcing material volume percentage 10%-20%, with 100% total volume percentage sum;In which inorganic filler includes any one or two mixtures in hollow glass microsphere, hollow ball silicon;Step 3, add a layer of copper foil above and below the medium layer, then add steel plate on the upper and lower surfaces of copper foil, then put into high-temperature press and press to prepare high-frequency copper-clad plate.Hollow closed spherical filler is compounded according to certain proportion, which can significantly reduce the dielectric constant of plate, and also reduce the expansion coefficient and loss of plate.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of copper-clad plate production and manufacturing, and relates to a preparation method of a low-dielectric low-expansion polytetrafluoroethylene high-frequency copper-clad plate. BACKGROUND

[0002] With the rapid development and popularization of the fifth generation mobile communication technology (5G), digital circuits gradually enter the stage of information processing high-speed and signal transmission high-frequency. In order to process increasing data, the frequency of electronic devices becomes higher and higher, and high-frequency copper-clad plates will develop towards the trend of low dielectric constant (Dk), low thermal expansion coefficient (Df), thin multi-layer and heat resistance, so as to meet the needs of current and future electronic and communication products.

[0003] In the manufacturing process of the copper-clad plate, the addition of fillers is a direct means to increase the performance, function and value of the copper-clad plate. If the fillers are reasonably added and used, the performance of the copper-clad plate can be improved or improved, otherwise negative effects will be brought. If the fillers are not uniformly dispersed in the resin system, the matrix resin is not well wetted, penetrated and coated, or the PVC (volume concentration) of the fillers is greater than CPVC (critical volume concentration), there will be a large number of bad interfaces, air gaps and defects in the composite system, which will reduce the various performances of the copper-clad plate. For example: immersion, float welding; T288, T300, thermal stability; breakdown voltage; moisture absorption; internal stress, warping, CAF, CTI, etc. In addition, with the addition of fillers, the dielectric properties and thermal stability of the copper-clad plate will be improved, but it is difficult to prepare a low-dielectric low-expansion high-frequency copper-clad plate containing fillers.

[0004] Therefore, it is necessary to improve the prior art to overcome the defects in the prior art. SUMMARY

[0005] The purpose of the present application is to provide a preparation method of a low-dielectric low-expansion polytetrafluoroethylene high-frequency copper-clad plate, which improves the fillers and a low-dielectric low-expansion high-frequency copper-clad plate containing fillers.

[0006] The purpose of the present application is achieved by the following technical scheme:

[0007] A preparation method of a low-dielectric low-expansion polytetrafluoroethylene high-frequency copper-clad plate, comprising the following steps:

[0008] Step 1, preparing glue, the glue includes glue A and glue B; wherein the preparation method of glue A is: after the inorganic filler is treated with silane coupling agent, then under the condition of high speed shearing, the mixture of water and inorganic filler is mixed and dispersed with fluorine resin emulsion to prepare glue A; the preparation method of glue B is: after the short glass fiber of LOW DK is treated with silane coupling agent, then under the condition of high speed shearing, the mixture of water and short glass fiber is mixed and dispersed with fluorine resin emulsion to prepare glue B; the above fluorine resin emulsion adopts polytetrafluoroethylene emulsion.

[0009] Step 2, medium layer preparation: after glue A and glue B are coated on glass fiber cloth on high temperature gluing machine for multiple times, drying, low temperature baking and high temperature baking, the medium layer is prepared, wherein glue B is used for the last coating; the medium layer includes the following components: fluorine resin volume percentage 12%-25%, silane coupling agent volume percentage 3%-6%, inorganic filler volume percentage 60-65%, reinforcing material volume percentage 10%-20%, taking the total volume percentage as 100%; wherein the inorganic filler includes any one or mixture of two of hollow glass microbeads and hollow sphere silicon, and the above hollow glass microbeads and hollow sphere silicon are hollow and closed spherical fillers;

[0010] Step 3, compression molding: one layer of copper foil is added above and below the medium layer, and then steel plates are added on the upper and lower surfaces of the copper foil, and then the high frequency copper clad plate is prepared by compression molding in a high temperature press.

[0011] Further, taking the total volume percentage as 100%, the volume percentage of the hollow glass microbeads is 0-100%, and the volume percentage of the hollow sphere silicon is 0-100%.

[0012] Further, the short glass fiber is LOW DK glass fiber, the length is 100-150 μm, the diameter is 1-3 μm, and the coating thickness of glue B is 10-15 μm.

[0013] Further, the silane coupling agent is mixed with water in proportion, the inorganic filler is added after sufficient stirring at a temperature of 30-45℃, high speed stirring is carried out at a speed of 4500-5500 rpm / min, the first mixture is obtained after stirring for 20-30 mins; the first mixture is dried; after drying, the first mixture, water and fluorine resin are mixed at a temperature of 30-45℃, stirring is carried out at a speed of 4000-5500 rpm / min, and glue A is obtained after stirring for 60-90 mins.

[0014] Further, the silane coupling agent is mixed with water in a ratio of 1:20 in the preparation of the first mixture, and stirring is performed at a temperature of 30-45℃ and a speed of 50rpm / min-80rpm / min, and the inorganic filler is added after 30-40mins of stirring; the temperature for drying the first mixture is 150-200℃, and the drying time is 60mins.

[0015] Further, the silane coupling agent includes one or a combination of several of gamma-glycidoxypropyltrimethoxysilane, gamma-glycidoxypropyltriethoxysilane, vinyltriethoxysilane, and octyltriethoxysilane.

[0016] Further, the fluorine-based resin includes any one of polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer, or perfluoroethylene propylene copolymer, or a mixture of at least two thereof.

[0017] Further, the time required for air-drying the glass fiber cloth coated with glue in step 2 is 30mins; the temperature for low-temperature baking is 150-200℃, and the time for low-temperature baking is 10-15mins; the temperature for high-temperature baking is 300℃, and the time for high-temperature baking is 10-15mins.

[0018] Further, the temperature for pressing in the high-temperature press in step 3 is set to 380-400℃, the pressure is set to 50-70kg, and the pressing time is usually 180mins.

[0019] The above technical solution has the following beneficial effects: hollow and closed spherical fillers, hollow glass beads and hollow sphere silicon, are used to replace conventional fillers such as silicon dioxide, titanium dioxide, and aluminum oxide, and the hollow glass beads and hollow sphere silicon have the advantages of low density, low dielectric constant, thermal stability, good insulation, and low thermal expansion coefficient, which can effectively reduce the dielectric constant and thermal expansion of the plate material, and the production process is similar to the conventional production process, which is convenient for production. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only exemplary, and for those skilled in the art, other drawings can be derived from the provided drawings without creative labor.

[0021] The structures, proportions, sizes, etc. shown in the specification are merely used to cooperate with the content disclosed in the specification, to be understood and read by those skilled in the art, and do not have technical substantial significance, and any modification of the structure, change of the proportion relationship or adjustment of the size, without affecting the effects and purposes that can be achieved by the application, should still fall within the scope of the disclosed technology.

[0022] Figure 1 The process flow diagram provided by the present application. DETAILED DESCRIPTION

[0023] The specific embodiments of the application will be further described below with reference to the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the application, but does not constitute a limitation on the application. In addition, the technical features involved in the various embodiments of the application described below can be combined with each other as long as they do not conflict with each other.

[0024] Referring to Figure 1 As shown in the figure, a method for preparing a low-dielectric low-expansion polytetrafluoroethylene high-frequency copper-clad plate uses two hollow sealed spherical fillers, which are added to the polytetrafluoroethylene emulsion by compounding to prepare a high-frequency copper-clad plate with ultra-low dielectric and low expansion. The specific steps are as follows:

[0025] According to Table 1, select the materials:

[0026] Table 1: Different raw material addition amounts

[0027]

[0028] Among them: in experiment 1, the silane coupling agent is γ-glycidyl ether propyl trimethoxysilane, and the fluorine resin is polytetrafluoroethylene;

[0029] In experiment 2, the silane coupling agent is γ-glycidyl ether propyl triethoxysilane, and the fluorine resin is tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer;

[0030] In experiment 3, the silane coupling agent is vinyl triethoxysilane, and the fluorine resin is perfluoroethylene propylene copolymer;

[0031] In experiment 4, the silane coupling agent is octyl triethoxysilane, and the fluorine resin is polytetrafluoroethylene.

[0032] In experiments 1-4, the inorganic filler is selected from hollow glass beads and / or hollow silica spheres, and the specific addition amount of experiments 1-4 is shown in Table 2:

[0033] Table 2: Different types of inorganic filler addition amount

[0034] Experiment Hollow glass microsphere volume percentage Hollow sphere silica volume percentage Experiment 1 filler 100 0 Experiment 2 filler 0 100 Experiment 3 filler 50 50 Experiment 4 filler 30 70

[0035] The hollow glass microsphere and hollow ball silicon used in the embodiment have the following performance requirements:

[0036]

[0037] Step 1. Prepare the glue as shown in Figure 1 The above glue includes glue A and glue B. Wherein:

[0038] The preparation method of glue A is: after the inorganic filler is treated with silane coupling agent, the mixture of water and inorganic filler is mixed and dispersed with fluorine resin emulsion under the condition of high speed shearing to obtain glue A.

[0039] The preparation method of glue B is: after the short glass fiber of LOW DK is treated with silane coupling agent, the mixture of water and short glass fiber is mixed and dispersed with fluorine resin emulsion under the condition of high speed shearing to obtain glue B, the length of the above short glass fiber is 100-150 μm, the diameter is 1-3 μm, and the coating thickness is 10-15 μm.

[0040] Further, the silane coupling agent is mixed with water in a ratio of 1:20, stirred at a temperature of 30-45℃ and a speed of 50rpm / min-80rpm / min, after stirring for 30-40mins, the inorganic filler is added, and stirred at a speed of 4500-5500rpm / min, after stirring for 20-30mins, a first mixture is obtained; the first mixture is dried, baked at a temperature of 150-200℃ for 60mins; then the water, the dried first mixture and the fluorine resin are mixed at a temperature of 30-45℃, stirred at a speed of 4000-5500rpm / min, after stirring for 60-90mins, glue A is obtained.

[0041] The silane coupling agent is mixed with water in a ratio of 1:20, stirred at a temperature of 30-45℃ and a speed of 50rpm / min-80rpm / min, after stirring for 30-40mins, the short glass fiber is added, and stirred at a speed of 4500-5500rpm / min, after stirring for 20-30mins, a second mixture is obtained; the second mixture is dried, baked at a temperature of 150-200℃ for 60mins; then the water, the dried second mixture and the fluorine resin are mixed at a temperature of 30-45℃, stirred at a speed of 4000-5500rpm / min, after stirring for 60-90mins, glue B is obtained.

[0042] Step 2. The medium layer is prepared as follows: the glue A and glue B are coated on the glass fiber cloth by multiple times of impregnation coating, air drying, low temperature baking and high temperature baking on a high temperature gluing machine, and the glue B is coated last; the medium layer comprises the following components in a total volume percentage of 100%: fluorine resin 12%-25%, silane coupling agent 3%-6%, inorganic filler 60-65%, and reinforcing material 10%-20%; wherein the inorganic filler comprises any one or a mixture of both of hollow glass microbeads and hollow sphere silicon.

[0043] Further, the required time for air drying of the glass fiber cloth after impregnation coating with the glue A and glue B is about 30 mins, the temperature for low temperature baking is between 150-200℃, and the low temperature baking is performed for 10-15 mins; the temperature for high temperature baking is about 300℃, and the high temperature baking is performed for 10-15 mins.

[0044] Step 3. Multiple medium layers are taken, and a copper foil is added above and below each medium layer, and then a steel plate is added on the upper and lower surfaces of the copper foil, and then the copper foil and the steel plate are put into a high temperature press for pressing, the temperature is set to 380-400℃, the pressure is set to 50-70 kg, and the pressing is performed for 180 minutes to obtain a polytetrafluoroethylene high-frequency copper-clad plate.

[0045] Comparative Example

[0046] The copper-clad plates are prepared according to the proportions in Table 3, and the processing technology is the same as that in Experimental Examples 1-4.

[0047] Table 3 Comparative Experimental Example

[0048] Case Filler volume percentage Fluorine-based resin volume percentage E-glass fiber cloth volume percentage Silane coupling agent volume percentage Comparative experiment 1 0％ 50％ 45％ 5％ Comparative experiment 2 60％ 27％ 10％ 3％ Comparative experiment 3 62％ 19％ 16％ 3％

[0049] Note: In Comparative Experimental Examples 1-3, the filler is one or more of silica, titanium dioxide, boron nitride and alumina.

[0050] The performance of the copper-clad plates provided by Experimental Examples 1-4 and Comparative Experimental Examples 1-3 of the present disclosure is compared and tested, and the test results are shown in Table 4.

[0051] Table 4 Comparison of Performance Parameters of Copper-clad Plates

[0052]

[0053]

[0054] The above test methods are tested according to the industry test standards.

[0055] It can be seen from Table 4 that the conclusions of experiments 1-4 under different conditions are consistent. Without filler, the expansion coefficient of the plate is higher. With conventional filler, the expansion coefficient of the plate decreases, but the dielectric constant increases. With hollow and closed spherical filler compounded in a certain proportion, the dielectric constant of the plate can be obviously reduced, and the expansion coefficient and loss of the plate are also reduced.

[0056] The embodiments of the present application are described in detail above with reference to the drawings, but the present application is not limited to the described embodiments. For those skilled in the art, various changes, modifications, replacements and variations can be made to the embodiments without departing from the principles and spirits of the present application, and still fall within the protection scope of the present application.

Claims

1. A method for preparing a low-dielectric, low-expansion polytetrafluoroethylene high-frequency copper-clad laminate, characterized in that: The method comprises the following steps: Step 1, preparing glue, which comprises glue A and glue B; The preparation method of glue A is as follows: after the inorganic filler is treated with a silane coupling agent, the mixture of water and the inorganic filler is mixed and dispersed with a fluorine resin emulsion under high-speed shearing to obtain glue A; the preparation method of glue B is as follows: after the short glass fiber is treated with a silane coupling agent, the mixture of water and the short glass fiber is mixed and dispersed with a fluorine resin emulsion under high-speed shearing to obtain glue B; Step 2, medium layer preparation: after glue A and glue B and glass fiber cloth are coated, dried, low-temperature baked and high-temperature baked for multiple times on a high-temperature gluing machine, a medium layer is prepared, wherein glue B is used for the last coating; the medium layer comprises the following components in a total volume percentage of 100%: fluorine resin 12%-25%, silane coupling agent 3%-6%, inorganic filler 60-65%, and reinforcing material 10%-20%; the inorganic filler comprises any one or a mixture of both of hollow glass microbeads and hollow sphere silicon; Step 3, compression molding: a copper foil is added above and below the medium layer, and a steel plate is added on the upper and lower surfaces of the copper foil, and then the copper foil is put into a high-temperature press to obtain a high-frequency copper-clad plate; The inorganic filler comprises hollow glass microbeads and hollow sphere silicon in a total volume percentage of 100%, the volume percentage of the hollow glass microbeads is 30-50%, the volume percentage of the hollow sphere silicon is 50-70%, the length of the short glass fiber is 100-150 μm, the diameter of the short glass fiber is 1-3 μm, and the coating thickness of glue B is 10-15 μm.

2. The method of claim 1, wherein: The silane coupling agent and water are mixed in a certain proportion, and after being fully stirred at a temperature of 30-45℃, the inorganic filler is added, and high-speed stirring is performed at a speed of 4500-5500 rpm / min, and after stirring for 20-30 mins, a first mixture is obtained; the first mixture is dried; after drying, the first mixture, water and a fluorine resin are mixed at a temperature of 30-45℃, and stirring is performed at a speed of 4000-5500 rpm / min, and after stirring for 60-90 mins, glue A is obtained.

3. The method of claim 2, wherein: In the preparation of the first mixture, the silane coupling agent and water are mixed in a proportion of 1:20, and stirring is performed at a speed of 50 rpm / min-80 rpm / min at a temperature of 30-45℃, and after stirring for 30-40 mins, the inorganic filler is added; the drying temperature of the first mixture is 150-200℃, and the baking time is 60 mins.

4. The method of claim 1, wherein: The silane coupling agent comprises one or a combination of several of γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, vinyltriethoxysilane and octyltriethoxysilane.

5. The method of claim 1, wherein: The fluorine resin comprises any one or a mixture of at least two of polytetrafluoroethylene, tetrafluoroethylene-perfluoroalkoxy vinyl ether copolymer and perfluoroethylene propylene copolymer.

6. The method of claim 1, wherein: The time required for drying the glass fiber cloth impregnated with glue in Step 2 is 30 minutes; the temperature of low-temperature baking is between 150-200°C, and the time of low-temperature baking is between 10-15 minutes; the temperature of high-temperature baking is 300°C, and the time of high-temperature baking is between 10-15 minutes.

7. The method of claim 1, wherein: In Step 3, the temperature of the high-temperature press is set to 380-400°C, the pressure is set to 50-70kg, and the pressing time is usually 180 minutes.

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