Forsterite-polytetrafluoroethylene composite material and preparation method and application thereof

Abstract

Forsterite-polytetrafluoroethylene composite material and its preparation method and application, the preparation method of the forsterite-polytetrafluoroethylene composite material includes adding grease to spherical silicon-containing powder, infiltrating the silicon-containing powder until a colloidal mixture is formed; adding magnesium-containing powder to the colloidal mixture and mixing to obtain a spherical forsterite precursor; sintering the forsterite precursor to obtain spherical forsterite; and co-coagulating forsterite with a polytetrafluoroethylene emulsion to coat the surface of the forsterite with polytetrafluoroethylene, thereby obtaining a forsterite-polytetrafluoroethylene composite material. The forsterite-polytetrafluoroethylene composite material prepared in this application has good uniformity and dielectric properties, is suitable for the preparation of copper-clad laminates and printed circuit boards in the 5G field, can meet high-frequency and high-speed signal transmission, and has broad application prospects.

Description

Technical Field

[0001] The present application relates to the technical field of composite materials, and in particular to a forsterite-polytetrafluoroethylene composite material and a preparation method and application thereof. Background Art

[0002] With the rapid development of millimeter-wave high-frequency applications, higher requirements are being placed on high-frequency and high-speed signal transmission. Traditional circuit substrates cannot meet the requirements of 5G communications. Therefore, the development of a low-cost, high-performance, and highly stable high-frequency, high-speed microwave composite dielectric substrate is particularly important. Microwave composite dielectric substrates with low dielectric constants are very beneficial for the high-speed, low-latency, and lossless transmission of microwave signals, making them widely used in ultra-high-density and ultra-large-scale integrated circuits. Polytetrafluoroethylene, with its ultra-low dielectric constant and dielectric loss, has become one of the main substrate materials in the RF microwave field. To further improve the overall performance of the substrate, most microwave composite dielectric substrates are currently made of ceramic-filled polytetrafluoroethylene (PTFE).

[0003] However, existing methods for preparing ceramic-filled polytetrafluoroethylene (PTFE) are complex and lack practical application. Currently, they are still in the laboratory research stage, making industrial application difficult. Furthermore, to achieve a sufficient bond between the ceramic powder and PTFE, the ceramic powder surface is often modified using a coupling agent coating or other additives, further increasing the complexity of the process. Furthermore, the film thickness and uniformity of microwave composite dielectric substrates prepared using current methods are poor, and the dielectric properties need to be improved. Summary of the Invention

[0004] In view of this, the present application provides a method for preparing a forsterite-polytetrafluoroethylene (PTFE) composite material, which can improve the uniformity and dielectric properties of the forsterite-PTFE composite material.

[0005] In addition, the present application also provides a forsterite-PTFE composite material prepared by the aforementioned preparation method, as well as a copper clad laminate and a printed circuit board using the forsterite-PTFE composite material.

[0006] The present invention provides a method for preparing a forsterite-PTFE composite material, comprising the following steps:

[0007] Adding grease dropwise into the spherical silicon-containing powder to wet the silicon-containing powder until a colloidal mixture is formed;

[0008] adding magnesium-containing powder to the colloidal mixture and mixing to obtain a spherical forsterite precursor;

[0009] sintering the forsterite precursor to obtain spherical forsterite; and

[0010] The forsterite and PTFE emulsion are co-coagulated to coat the surface of the forsterite with PTFE, thereby obtaining the forsterite-PTFE composite material.

[0011] In some possible embodiments, in the colloidal mixture, the mass fraction of the oil is 15% to 30%, and the mass fraction of the silicon-containing powder is 70% to 85%.

[0012] In some possible embodiments, the molar ratio of the magnesium-containing powder to the silicon-containing powder is (1.5-2.3):1.

[0013] In some possible embodiments, the mass ratio of the forsterite to the PTFE in the PTFE emulsion is 1:(0.43-1).

[0014] In some possible embodiments, the sintering temperature is 800° C. to 1100° C., and the sintering time is 2 hours to 8 hours.

[0015] In some possible embodiments, the oil includes at least one of dibutyl phthalate, liquid paraffin, petroleum ether, toluene, xylene, diethyl phthalate, dibenzyl phthalate, diisooctyl phthalate and diphenyl phthalate.

[0016] In some possible embodiments, the silicon-containing powder includes at least one of silicon powder, silicate, and silicon oxide;

[0017] The magnesium-containing powder includes at least one of magnesium hydroxide, magnesium oxide, magnesium chloride and magnesium sulfate.

[0018] The embodiment of the present application further provides a forsterite-PTFE composite material, which is prepared by the aforementioned preparation method.

[0019] An embodiment of the present application further provides a copper-clad laminate, which includes a substrate and a metal layer located on the surface of the substrate, and the substrate is made of the aforementioned forsterite-PTFE composite material.

[0020] An embodiment of the present application further provides a printed circuit board, which includes a substrate and a circuit layer located on a surface of the substrate, wherein the substrate is made of the aforementioned forsterite-PTFE composite material.

[0021] Compared to prior art, the preparation method of the forsterite-PTFE composite material provided by the present application embodiment, by first dripping grease into the silicon-containing powder of spherical, silicon-containing powder is semi-plasticized, then mixed with magnesium-containing powder, this novel step-by-step mixing method effectively improves the mixing effect of silicon-containing powder and magnesium-containing powder, is conducive to obtaining spherical forsterite with uniform morphology and less surface defects, thereby improving the compatibility of forsterite and PTFE, making the forsterite-PTFE composite material prepared have more uniform structure and interface, and the spherical forsterite of the preparation method can directly complete co-coagulation with PTFE, no longer needing to carry out surface modification or adding auxiliary agent to forsterite, reducing the impact of additives such as auxiliary agents on forsterite-PTFE composite material performance, the uniformity of the forsterite-PTFE composite material obtained is better, while having excellent dielectric properties. The preparation method process is simple, practical, efficient, and relatively low in cost, and the continuous large-scale production of forsterite-PTFE composite material can be achieved. The copper clad laminate prepared using the forsterite-PTFE composite material provided in the embodiments of the present application has a low dielectric constant and dielectric loss, and the prepared printed circuit board has excellent performance, is stable and reliable, and can meet the requirements of high-frequency and high-speed signal transmission. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a process flow chart of the preparation method of the forsterite-polytetrafluoroethylene composite material provided in the examples of the present application.

[0023] Figure 2 This is a scanning electron microscope image of forsterite in Example 1 of the present application.

[0024] Figure 3 This is a scanning electron microscope image of the forsterite-polytetrafluoroethylene composite material in Example 1 of the present application.

[0025] Figure 4 This is a scanning electron microscope image of the forsterite-polytetrafluoroethylene composite material in Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0026] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making any creative work shall fall within the scope of protection of the present application.

[0027] See also Figure 1 As shown, the preparation method of the forsterite-polytetrafluoroethylene (PTFE) composite material provided in the embodiment of the present application specifically includes the following steps:

[0028] Step S1: Add grease dropwise into spherical silicon-containing powder to wet the silicon-containing powder until a gel-like mixture is formed.

[0029] Step S2: adding magnesium-containing powder to the colloidal mixture and mixing to obtain a spherical forsterite precursor.

[0030] Step S3: sintering the forsterite precursor to obtain spherical forsterite.

[0031] Step S4: co-coagulating forsterite and PTFE emulsion to coat the surface of the forsterite with PTFE, thereby obtaining a forsterite-PTFE composite material.

[0032] In step S1: gradually add grease to the spherical silicon-containing powder, so that the grease completely soaks the silicon-containing powder until a viscous colloid is formed, thereby semi-plasticizing the silicon-containing powder. When the grease is mixed with the silicon-containing powder, the grease molecules can form a lubricating film between the silicon-containing powders, which is beneficial to reduce the surface energy of the silicon-containing powder, making it easier for the silicon-containing powder to undergo relative displacement during processing, thereby increasing the plasticity of the silicon-containing powder, which is beneficial for uniform mixing with the magnesium-containing powder in step S2. Among them, the silicon-containing powder is a spherical silicon-containing powder. This spherical silicon-containing powder has better fluidity and can be evenly mixed with the magnesium-containing powder. The use of spherical silicon-containing powder can make the subsequently prepared forsterite also spherical.

[0033] Prior to the step of impregnating the silicon-containing powder with grease, the preparation method may further include drying the silicon-containing powder at a temperature of 100°C to 140°C for 10 to 24 hours. This pre-drying of the silicon-containing powder is intended to remove moisture and volatile substances from the silicon-containing powder, thereby improving its stability and workability.

[0034] In step S1, the mass fraction of the oil in the colloidal mixture can be 15% to 30%, and further can be 20% to 30%. For example, the mass fraction of the oil can be 15%, 18%, 20%, 22%, 25%, 28%, or 30%. The mass fraction of the silicon-containing powder can be 70% to 85%, and further can be 70% to 80%. For example, the mass fraction of the silicon-containing powder can be 70%, 75%, 78%, 80%, 82%, 84%, or 85%. A suitable mixing ratio of oil and silicon-containing powder can further improve the surface modification effect while maintaining the desired silicon-containing powder content and processing properties.

[0035] In step S1, the silicon-containing powder may include at least one of silicon micropowder, silicate, and silicon oxide. These silicon-containing powders all have advantages such as thermal stability, chemical stability, mechanical strength, and low cost and availability. Using these silicon-containing powders to fill polytetrafluoroethylene can further enhance the excellent dielectric and mechanical properties of the polytetrafluoroethylene. Exemplary silicon-containing powders may include silicon micropowder or silicon dioxide.

[0036] In step S1, the particle size D50 of the silicon-containing powder can be 4 μm to 16 μm. Silicon-containing powder within this particle size range can more easily form a uniform colloidal mixture when mixed with oil, which helps to form a spherical, uniform forsterite precursor, thereby improving the sphericity and performance of the forsterite. The particle size D50 of the silicon-containing powder can further be 6 μm to 12 μm, and can be 4 μm, 6 μm, 8 μm, 10 μm, 12 μm, 14 μm, or 16 μm, for example.

[0037] In step S1, the oil can include at least one of dibutyl phthalate, liquid paraffin, petroleum ether, toluene, xylene, diethyl phthalate, dibenzyl phthalate, diisooctyl phthalate, and diphenyl phthalate. The oils within the above range can all semi-plasticize the silicon-containing powder well.

[0038] In step S2, magnesium-containing powder is added to the colloidal mixture of silicon-containing powder and oil, and the mixture is mixed until the two are thoroughly mixed into a dough-like state, thereby obtaining a spherical forsterite precursor. Because the silicon-containing powder has become a semi-plastic fluid under the action of the oil, the magnesium-containing powder is more evenly mixed into the colloidal mixture, thereby increasing the sphericity of the forsterite and avoiding the formation of flaky or polygonal structures. Ultimately, a spherical forsterite precursor with good uniformity is obtained.

[0039] In step S2, a sintering aid can also be added and mixed. The sintering aid can include at least one of lithium fluoride, sodium fluoride, and aluminum fluoride. This sintering aid can effectively reduce the sintering temperature of the forsterite precursor and increase the sintered density. The mass fraction of the sintering aid in the forsterite precursor can be 0.8% to 2%, which can reduce the sintering temperature and increase the sintered density.

[0040] The molar ratio of the magnesium-containing powder added in step S2 to the silicon-containing powder in step S1 can be (1.5-2.3):1. This molar ratio range is conducive to the reaction to form forsterite (Mg2SiO4). The molar ratio can further be (2-2.3):1, and illustratively can be 1.5:1, 1.8:1, 2:1, 2.1:1, 2.2:1, or 2.3:1.

[0041] In step S2 , the magnesium-containing powder may include at least one of magnesium hydroxide, magnesium oxide, magnesium chloride, magnesium sulfate, and the like, and illustratively may be magnesium hydroxide.

[0042] In step S3: the forsterite precursor is sintered to obtain spherical forsterite. Since the forsterite precursor has good consistency and the components are evenly distributed, the obtained forsterite has a uniform morphology.

[0043] Since spherical silicon-containing powder is used in step S1, and the silicon-containing powder and magnesium-containing powder are dispersed more evenly and fully contacted under the action of oil infiltration, spherical forsterite with better surface morphology is formed. Forsterite with such a spherical structure has many advantages, including: (1) good fluidity, because the friction of spherical forsterite is smaller than that of irregularly shaped forsterite, it is easier to mix with PTFE in the subsequent process; (2) improved sintering performance, spherical particles can contact and fuse more evenly during high-temperature sintering, which helps to reduce sintering defects and thus form a uniform structure; (3) uniform distribution, spherical forsterite particles can be more evenly distributed in PTFE during the co-coagulation process, reducing particle aggregation, which is crucial for the subsequent molding process and can ensure the quality and consistency of the final product; (4) high density and high strength, spherical particles help to form a denser composite material structure, thereby improving the wear resistance and corrosion resistance of the forsterite-PTFE composite material.

[0044] In step S3, the sintering heating rate can be 2°C / min to 5°C / min, the sintering temperature can be 800°C to 1100°C, and the sintering time can be 2 hours to 8 hours. The forsterite precursor is uniformly heated to ensure sufficient sintering to form the desired forsterite.

[0045] In step S4: forsterite is fully dispersed in the solvent, then add PTFE emulsion to mix and carry out co-coagulation, PTFE is coated on the surface of forsterite, then the co-coagulation product is carried out to solid-liquid separation and the co-coagulation product (solid powder) is dried, obtain forsterite-PTFE composite material.Wherein, spherical forsterite and PTFE emulsion have good compatibility, can realize the uniform mixing of forsterite and PTFE when forsterite is not needed to being carried out surface modification or adding auxiliary agent, complete co-coagulation, greatly reduce the impact of coupling agent or other auxiliary agents on product performance.Simultaneously because the compatibility of forsterite and PTFE is better, PTFE can evenly coat forsterite, thus the forsterite-PTFE composite material made has more uniform structure and interface, improves dielectric property and the homogeneity of forsterite-PTFE composite material.

[0046] In step S4, the mass ratio of forsterite to solvent can be 1:(3-6), which is conducive to the full dispersion of forsterite in the solution. The mass ratio of forsterite to solution can further be 1:(4-5), and illustratively can be 1:3, 1:3.5, 1:4, 1:4.5, 1:4.6, 1:5, 1:5.5 or 1:6, etc.

[0047] In step S4, the mass ratio of forsterite to PTFE in the PTFE emulsion can be 1:(0.43-1), and can further be 1:(0.5-0.6), and can exemplarily be 1:0.43, 1:0.45, 1:0.5, 1:0.54, 1:0.6, 1:0.7, 1:0.8, 1:0.9 or 1:1, etc., which is conducive to further meeting the performance requirements of forsterite-PTFE composite materials.

[0048] In step S4, the solvent may be water, and further may be deionized water, which can effectively reduce the interference of impurities and improve the quality of the forsterite-PTFE composite material.

[0049] Compared with the prior art, the preparation method of the forsterite-PTFE composite material provided in the embodiment of the present application has the following beneficial effects:

[0050] 1. A step-by-step mixing method is used, whereby grease is added dropwise to silicon-containing powder, the silicon-containing powder is semi-plasticized, and then magnesium-containing powder is added and thoroughly mixed. This step-by-step mixing method produces spherical forsterite with a well-defined morphology, thereby improving the compatibility of forsterite with PTFE, and enhancing the dielectric properties and uniformity of the forsterite-PTFE composite. This mixing method also exhibits excellent uniformity and stability. Furthermore, this mixing method provides a new and efficient solution for the preparation of composite dielectric substrate materials, facilitating the large-scale production of forsterite-PTFE composites.

[0051] 2. The process flow is simplified and the performance of subsequent products is improved. Forsterite can be directly co-coagulated with PTFE without the need for additional surface modification of the forsterite or the addition of additives, thereby reducing the impact of additional additives on the performance of subsequent products. The preparation process of the forsterite-PTFE composite material of the present application is simple, and the obtained forsterite-PTFE composite material has excellent performance.

[0052] The present invention provides a forsterite-PTFE composite material, which is prepared by the aforementioned preparation method. Compared with the prior art, the forsterite-PTFE composite material provided in the present invention has excellent dielectric properties and uniformity, which is beneficial for the forsterite-PTFE composite material to maintain stable performance and low dielectric loss during high-frequency, high-speed signal transmission when used in copper-clad laminates and printed circuit boards, thereby extending the service life.

[0053] The present application also provides a copper-clad laminate (CCL) comprising a substrate and a metal layer disposed on a surface of the substrate. The substrate is made of the aforementioned forsterite-PTFE composite material. Compared to existing technologies, the CCL provided in the present application has a low dielectric constant and low dielectric loss, ensuring stable and complete signal transmission for high-speed and high-frequency circuits.

[0054] In some embodiments, before preparing the copper clad laminate, a certain amount of isoparaffin additive can be further added to the obtained forsterite-PTFE composite material, and the polytetrafluoroethylene composite material after adding the additive is aged at 25°C to 60°C for 1 hour to 3 hours. During the aging process, the structure of the forsterite-PTFE composite material gradually stabilizes and solidifies from powder to block, which is beneficial to improving the processing performance and subsequent treatment stability of the forsterite-PTFE composite material. Wherein, the mass ratio of the forsterite-PTFE composite material to the isoparaffin additive is 1:(0.3-0.5), and can further be 1:(0.3-0.4), and can be illustratively 1:0.3, 1:0.33, 1:0.4, 1:0.45 or 1:0.5, etc.

[0055] The present application also provides a printed circuit board (PCB) comprising a substrate and a circuit layer located on a surface of the substrate, wherein the substrate is made of the aforementioned forsterite-PTFE composite material. This PCB effectively reduces signal propagation delay and attenuation, helping to maintain signal integrity and stability. It also effectively reduces energy loss during signal transmission, ensuring high-speed and accurate signal transmission. Taking these advantages into account, this PCB ensures stable and complete signal transmission in high-speed, high-frequency circuits, meeting the increasingly complex and rapidly evolving demands of communications and data processing.

[0056] The forsterite-PTFE composite material and its preparation method and application are further described below through specific examples.

[0057] Example 1

[0058] Step 1: Place the spherical silicon micropowder in a forced air drying oven at 120° C. for 24 hours to remove moisture, soak the dried spherical silicon micropowder with dibutyl phthalate, and mix thoroughly until a colloidal mixture is formed, wherein the mass ratio of dibutyl phthalate to the dried spherical silicon micropowder is 3:7.

[0059] Step 2: Add magnesium hydroxide and lithium fluoride sintering aids to the colloidal mixture and mix to obtain a forsterite precursor, wherein the molar ratio of microsilica powder to magnesium hydroxide in the slurry is 1:2, and the mass ratio of microsilica powder to lithium fluoride is 1:0.03.

[0060] Step 3: calcining the forsterite precursor in a muffle furnace at a heating rate of 5°C / min and sintering at 800°C for 2 hours to obtain spherical forsterite.

[0061] Step 4, dispersing the spherical forsterite obtained in step 4 in deionized water, fully dispersing at 1500 rpm for 30 minutes, then adjusting the speed to 500 rpm, adding PTFE emulsion, wherein the mass ratio of spherical forsterite, deionized water and PTFE contained in the PTFE emulsion is 1:5:0.54, and co-coagulation is performed to obtain a co-coagulation complex, and the co-coagulation complex is separated into solid and liquid, and the white powder complex of the lower layer is taken and dried at 120 ° C for 8 hours to obtain a forsterite-PTFE composite material.

[0062] Step 5, adding an isoparaffin additive to the forsterite-PTFE composite material, wherein the mass ratio of the isoparaffin additive to the forsterite-PTFE composite material is 1:3, and aging at 60°C for 1 hour to obtain a uniform composite, which is then extruded, calendered, laminated, and copper-clad on both sides for high-temperature pressing at 380°C to obtain a spherical forsterite-filled PTFE-based copper-clad laminate.

[0063] Example 2

[0064] Step 1: Place the spherical silicon micropowder in a forced air drying oven at 120° C. for 24 hours to remove moisture, soak the dried spherical silicon micropowder with dibutyl phthalate, and mix thoroughly until a colloidal mixture is formed, wherein the mass ratio of dibutyl phthalate to the dried spherical silicon micropowder is 2:8.

[0065] Step 2: Add magnesium hydroxide and lithium fluoride sintering aids to the colloidal mixture and mix to obtain a forsterite precursor, wherein the molar ratio of microsilica powder to magnesium hydroxide in the slurry is 1:2, and the mass ratio of microsilica powder to lithium fluoride is 1:0.03.

[0066] Step 3: calcining the forsterite precursor in a muffle furnace at a heating rate of 5°C / min and sintering at 800°C for 2 hours to obtain spherical forsterite.

[0067] Step 4, dispersing the spherical forsterite obtained in step 4 in deionized water, fully dispersing at 1500 rpm for 30 minutes, then adjusting the speed to 500 rpm, adding PTFE emulsion, wherein the mass ratio of spherical forsterite, deionized water and PTFE contained in the PTFE emulsion is 1:5:0.54, and co-coagulation is performed to obtain a co-coagulation complex, and the co-coagulation complex is separated into solid and liquid, and the white powder complex of the lower layer is taken and dried at 120 ° C for 8 hours to obtain a forsterite-PTFE composite material.

[0068] Step 5, adding an isoparaffin additive to the forsterite-PTFE composite material, wherein the mass ratio of the isoparaffin additive to the forsterite-PTFE composite material is 1:3, and aging at 60°C for 1 hour to obtain a uniform composite, which is then extruded, calendered, laminated, and copper-clad on both sides for high-temperature pressing at 380°C to obtain a spherical forsterite-filled PTFE-based copper-clad laminate.

[0069] Example 3

[0070] Step 1: Place the spherical silicon micropowder in a forced air drying oven at 120° C. for 24 hours to remove moisture, soak the dried spherical silicon micropowder with dibutyl phthalate, and mix thoroughly until a colloidal mixture is formed, wherein the mass ratio of dibutyl phthalate to the dried spherical silicon micropowder is 3:7.

[0071] Step 2: Add magnesium hydroxide and lithium fluoride sintering aids to the colloidal mixture and mix to obtain a forsterite precursor, wherein the molar ratio of microsilica powder to magnesium hydroxide in the slurry is 1:2, and the mass ratio of microsilica powder to lithium fluoride is 1:0.03.

[0072] Step 3: calcining the forsterite precursor in a muffle furnace at a heating rate of 5°C / min and sintering at 900°C for 2 hours to obtain spherical forsterite.

[0073] Step 4, dispersing the spherical forsterite obtained in step 4 in deionized water, fully dispersing at 1500 rpm for 30 minutes, then adjusting the speed to 500 rpm, adding PTFE emulsion, wherein the mass ratio of spherical forsterite, deionized water and PTFE contained in the PTFE emulsion is 1:5:0.54, and co-coagulation is performed to obtain a co-coagulation complex, and the co-coagulation complex is separated into solid and liquid, and the white powder complex of the lower layer is taken and dried at 120 ° C for 8 hours to obtain a forsterite-PTFE composite material.

[0074] Step 5, adding an isoparaffin additive to the forsterite-PTFE composite material, wherein the mass ratio of the isoparaffin additive to the forsterite-PTFE composite material is 1:3, and aging at 60°C for 1 hour to obtain a uniform composite, which is then extruded, calendered, laminated, and copper-clad on both sides for high-temperature pressing at 380°C to obtain a spherical forsterite-filled PTFE-based copper-clad laminate.

[0075] Comparative Example 1

[0076] Step 1: Place the spherical silicon powder in a blast drying oven at 120°C for 24 hours to remove moisture, add magnesium hydroxide and lithium fluoride sintering aids to the spherical silicon powder and mix them to obtain a forsterite precursor, wherein the molar ratio of silicon powder to magnesium hydroxide is 1:2, and the mass ratio of silicon powder to lithium fluoride is 1:0.03.

[0077] Step 2: calcining the forsterite precursor in a muffle furnace at a heating rate of 5°C / min and sintering at 800°C for 2 hours to obtain spherical forsterite.

[0078] Step 3, dispersing the spherical forsterite obtained in step 4 in deionized water, fully dispersing at 1500 rpm for 30 minutes, then adjusting the speed to 500 rpm, adding PTFE emulsion, wherein the mass ratio of spherical forsterite, deionized water and PTFE contained in the PTFE emulsion is 1:5:0.54, and co-coagulation is performed to obtain a co-coagulation complex, and the co-coagulation complex is separated into solid and liquid, and the white powder complex of the lower layer is taken and dried at 120 ° C for 8 hours to obtain a forsterite-PTFE composite material.

[0079] Step 4, adding an isoparaffin additive to the forsterite-PTFE composite material, wherein the mass ratio of the isoparaffin additive to the forsterite-PTFE composite material is 1:3, and aging at 60°C for 1 hour to obtain a uniform composite, which is then extruded, calendered, laminated, and copper-clad on both sides for high-temperature pressing at 380°C to obtain a spherical forsterite-filled PTFE-based copper-clad laminate.

[0080] Comparative Example 2

[0081] Step 1: Place the spherical silicon powder in a blast drying oven at 120°C for 24 hours to remove moisture, add dibutyl phthalate, magnesium hydroxide and lithium fluoride sintering aids to the dried spherical silicon powder and mix to obtain a forsterite precursor, wherein the molar ratio of silicon powder to magnesium hydroxide is 1:2, and the mass ratio of dibutyl phthalate, silicon powder and lithium fluoride is 3:7:0.21.

[0082] Step 2: calcining the forsterite precursor in a muffle furnace at a heating rate of 5°C / min and sintering at 800°C for 2 hours to obtain spherical forsterite.

[0083] Step 3, dispersing the spherical forsterite obtained in step 4 in deionized water, fully dispersing at 1500 rpm for 30 minutes, then adjusting the speed to 500 rpm, adding PTFE emulsion, wherein the mass ratio of spherical forsterite, deionized water and PTFE contained in the PTFE emulsion is 1:5:0.54, and co-coagulation is performed to obtain a co-coagulation complex, and the co-coagulation complex is separated into solid and liquid, and the white powder complex of the lower layer is taken and dried at 120 ° C for 8 hours to obtain a forsterite-PTFE composite material.

[0084] Step 4, adding an isoparaffin additive to the forsterite-PTFE composite material, wherein the mass ratio of the isoparaffin additive to the forsterite-PTFE composite material is 1:3, and aging at 60°C for 1 hour to obtain a uniform composite, which is then extruded, calendered, laminated, and copper-clad on both sides for high-temperature pressing at 380°C to obtain a spherical forsterite-filled PTFE-based copper-clad laminate.

[0085] Comparative Example 3

[0086] Step 1: Place the spherical silicon micropowder in a blast drying oven at 120° C. for 24 hours to remove moisture, add magnesium hydroxide and lithium fluoride sintering aids to the dried spherical silicon micropowder and mix to obtain a mixture, wherein the molar ratio of silicon powder to magnesium hydroxide in the mixture is 1:2, and the mass ratio of silicon powder to lithium fluoride is 1:0.03.

[0087] Step 2: Add dibutyl phthalate to the mixture to obtain a forsterite precursor, wherein the mass ratio of dibutyl phthalate to the microsilica powder in the mixture is 3:7.

[0088] Step 3: calcining the forsterite precursor in a muffle furnace at a heating rate of 5°C / min and sintering at 800°C for 2 hours to obtain spherical forsterite.

[0089] Step 4, dispersing the spherical forsterite obtained in step 4 in deionized water, fully dispersing at 1500 rpm for 30 minutes, then adjusting the speed to 500 rpm, adding PTFE emulsion, wherein the mass ratio of spherical forsterite, deionized water and PTFE contained in the PTFE emulsion is 1:5:0.54, and co-coagulation is performed to obtain a co-coagulation complex, and the co-coagulation complex is separated into solid and liquid, and the white powder complex of the lower layer is taken and dried at 120 ° C for 8 hours to obtain a forsterite-PTFE composite material.

[0090] Step 5, adding an isoparaffin additive to the forsterite-PTFE composite material, wherein the mass ratio of the isoparaffin additive to the forsterite-PTFE composite material is 1:3, and aging at 60°C for 1 hour to obtain a uniform composite, which is then extruded, calendered, laminated, and copper-clad on both sides for high-temperature pressing at 380°C to obtain a spherical forsterite-filled PTFE-based copper-clad laminate.

[0091] 1. The forsterite, forsterite-PTFE composite material (after calendering treatment) in Example 1 and the forsterite-PTFE composite material (after calendering treatment) in Comparative Example 1 were observed using a scanning electron microscope.

[0092] The scanning electron microscope image of the forsterite prepared in Example 1 is as follows: Figure 2 As shown by Figure 2 It can be seen that the forsterite prepared in Example 1 is spherical, which is conducive to more uniform mixing with PTFE. The microscopic morphology of the forsterite-PTFE composite material (after calendering treatment) prepared in Example 1 is as follows Figure 3 As shown by Figure 3 It can be seen that PTFE uniformly wraps forsterite with good uniformity. This is because the addition of oil improves the plasticity of silicon powder, thereby improving the surface hydrophobicity of spherical forsterite, achieving uniform coating of PTFE on forsterite and ensuring good bonding between the two, which is conducive to obtaining forsterite-PTFE composite materials with excellent uniformity. The micromorphology of the forsterite-PTFE composite material (after calendering treatment) in Comparative Example 1 is as follows: Figure 4 As shown, PTFE cannot uniformly coat forsterite, and the forsterite-PTFE composite material has poor uniformity.

[0093] 2. The dielectric properties of the forsterite of Examples 1-3 and Comparative Examples 1-3 and the copper clad laminates with the surface copper foil etched away were tested. The results are shown in Table 1.

[0094] (1) Dielectric property test of forsterite: A cavity resonator fixture for measuring frequency of 10 GHz was used. After filling a sample tube made of PTFE with a powder sample, the dielectric property was measured by a vector network analyzer.

[0095] (2) Dielectric performance test of copper clad laminate: The dielectric performance is tested using the separated cylindrical resonant cavity method (a standard of the American Society for Testing and Materials, method number ASTM2520). First, prepare a 10 GHz test fixture and connect the fixture to the network analyzer. First, measure the center frequency f of the cavity. c and quality factor Q c , then insert the sample and measure the center frequency f again after loading the sample s And the loaded quality factor Q s The dielectric constant and loss are then calculated using the following formula:

[0096]

[0097] Among them, f c is the center frequency of the cavity, f s is the center frequency of the sample, Q cis the cavity quality factor, Q s is the sample quality factor, V c is the volume of the cavity, V s is the volume of the sample.

[0098] Table 1

[0099]

[0100] The results show that the forsterite prepared in Examples 1-3 exhibits lower dielectric loss than the forsterite prepared in Comparative Examples 1-3. This is because the mixing method adopted in the examples is step-by-step mixing, that is, the silicon-containing powder is first soaked in grease, and then the magnesium-containing powder is added, so that the silicon-containing powder and the magnesium-containing powder are mixed more evenly, which helps the forsterite to form a more uniform spherical structure. The spherical structure has good surface properties, thereby improving the dielectric properties of the forsterite.

[0101] Compared with the copper clad laminates in comparative examples 1-3, the copper clad laminates in examples 1-3 exhibit lower dielectric constants and dielectric losses, which indicates that the copper clad laminates provided in the examples of the present application have excellent dielectric properties.

[0102] Specifically analyze, in comparative example 1, silicon micropowder and magnesium-containing powder are directly mixed, grease is not added dropwise, the forsterite made is caused to be unable to be uniformly mixed with PTFE, resulting in poor dielectric properties after the copper clad plate etching surface copper foil obtained;In comparative example 2, grease, silicon-containing powder and magnesium-containing powder are mixed in one step, and grease fails to give full play to the modification of silicon-containing powder, and compared to the step-by-step mixing of embodiment 1-3, the dielectric properties of the copper clad plate obtained decline;In comparative example 3, silicon-containing powder and magnesium-containing powder are first pre-mixed, then grease is added dropwise to mix, due to the change of mixing mode, silicon-containing powder and magnesium-containing powder are caused to have uneven combination in the initial stage, and the grease added dropwise afterwards cannot effectively realize the semi-plasticization of silicon micropowder and the processing of hydrophobic modification. The forsterite obtained by 1-3 in comparative example has poor uniformity, and even part forsterite is non-spherical, causes subsequent polytetrafluoroethylene to be unable to evenly wrap forsterite, and the uniformity of obtained forsterite-PTFE composite material is poor, thus affecting the dielectric properties of copper clad plate.

[0103] It will be understood that the above embodiments are merely exemplary embodiments for illustrating the principles of the present invention, and the present invention is not limited thereto. Those skilled in the art will appreciate that various modifications and improvements can be made without departing from the spirit and substance of the present invention, and such modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A method for preparing a forsterite-polytetrafluoroethylene composite material, characterized in that: include: Adding grease dropwise into the spherical silicon-containing powder to wet the silicon-containing powder until a colloidal mixture is formed; adding magnesium-containing powder to the colloidal mixture and mixing to obtain a spherical forsterite precursor; sintering the forsterite precursor to obtain spherical forsterite; as well as The forsterite and polytetrafluoroethylene emulsion are co-coagulated to coat the surface of the forsterite with polytetrafluoroethylene, thereby obtaining the forsterite-polytetrafluoroethylene composite material.

2. The method for preparing the forsterite-polytetrafluoroethylene composite material according to claim 1, characterized in that: In the colloidal mixture, the mass fraction of the oil is 15% to 30%, and the mass fraction of the silicon-containing powder is 70% to 85%.

3. The method for preparing the forsterite-polytetrafluoroethylene composite material according to claim 1, characterized in that: The molar ratio of the magnesium-containing powder to the silicon-containing powder is (1.5-2.3):

1.

4. The method for preparing the forsterite-polytetrafluoroethylene composite material according to claim 1, characterized in that: The mass ratio of the forsterite to the polytetrafluoroethylene in the polytetrafluoroethylene emulsion is 1:(0.43-1).

5. The method for preparing the forsterite-polytetrafluoroethylene composite material according to claim 1, characterized in that: The sintering temperature is 800° C. to 1100° C., and the sintering time is 2 h to 8 h.

6. The method for preparing the forsterite-polytetrafluoroethylene composite material according to claim 1, characterized in that: The oil comprises at least one of dibutyl phthalate, liquid paraffin, petroleum ether, toluene, xylene, diethyl phthalate, dibenzyl phthalate, diisooctyl phthalate and diphenyl phthalate.

7. The method for preparing the forsterite-polytetrafluoroethylene composite material according to claim 1, characterized in that: The silicon-containing powder includes at least one of silicate and silicon oxide; The magnesium-containing powder includes at least one of magnesium hydroxide, magnesium oxide, magnesium chloride and magnesium sulfate.

8. The method for preparing the forsterite-polytetrafluoroethylene composite material according to claim 7, characterized in that: The silicon oxide includes silicon powder.

9. A forsterite-polytetrafluoroethylene composite material, characterized in that: The composite material is prepared by the method for preparing the forsterite-polytetrafluoroethylene composite material according to any one of claims 1 to 8.

10. A copper clad laminate, characterized in that: The invention comprises a substrate and a metal layer located on the surface of the substrate, wherein the substrate is made of the forsterite-polytetrafluoroethylene composite material according to claim 9.

11. A printed circuit board, characterized in that: The invention comprises a substrate and a circuit layer located on the surface of the substrate, wherein the substrate is made of the forsterite-polytetrafluoroethylene composite material according to claim 9.

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