阅读说明：本技术 一种包含中空陶瓷粉的低介电常数微波介质基板制备方法 (Preparation method of low-dielectric-constant microwave dielectric substrate containing hollow ceramic powder ) 是由 贾倩倩 郭晓光 张海涛 张立欣 金霞 鲁思如 孙伟 魏西 于 2019-11-01 设计创作，主要内容包括：本发明公开了一种包含中空陶瓷粉的低介电常数微波介质基板制备方法,其步骤为：将中空陶瓷粉进行表面改性,称取一定质量的改性中空陶瓷粉、聚四氟乙烯分散粉料进行混合,再向混合罐中加入一定质量的成型助剂并混合均匀,将复合物料放入挤出机挤出成型,得到圆柱形料坯；将圆柱形料坯反复压延,成为一定厚度的生基片,将生基片烘干；将烘干后的生基片叠层,双面覆铜箔,进行热压烧结,得到低介电常数微波复合介质基板。采用本方法制成的低介电常数微波介质基板介电常数降低至2.20以下,介电损耗低于0.0021。低介电常数的微波介质基板有助于高频信号的低延迟、低损耗传输,是富有潜力的用于高频高速电路板的基础材料。(The invention discloses a preparation method of a low-dielectric-constant microwave dielectric substrate containing hollow ceramic powder, which comprises the following steps: carrying out surface modification on hollow ceramic powder, weighing a certain mass of modified hollow ceramic powder and polytetrafluoroethylene dispersed powder for mixing, adding a certain mass of forming auxiliary agent into a mixing tank, uniformly mixing, and putting the composite material into an extruder for extrusion forming to obtain a cylindrical blank; repeatedly rolling the cylindrical blank to form a raw substrate with a certain thickness, and drying the raw substrate; and (3) laminating the dried green substrates, covering copper foils on two sides, and performing hot-pressing sintering to obtain the low-dielectric-constant microwave composite dielectric substrate. The dielectric constant of the low-dielectric-constant microwave dielectric substrate manufactured by the method is reduced to below 2.20, and the dielectric loss is lower than 0.0021. The microwave dielectric substrate with low dielectric constant is beneficial to low-delay and low-loss transmission of high-frequency signals, and is a potential base material for high-frequency and high-speed circuit boards.)

1. A method for preparing a low dielectric constant microwave dielectric substrate containing hollow ceramic powder is characterized by comprising the following steps:

(1) the method comprises the following steps of preparing a silane coupling agent, namely adding the silane coupling agent into a formic acid ethanol solution according to a ratio to prepare a modified solution, adopting a V-shaped mixer, filling hollow ceramic powder with a certain mass into a cavity of equipment, dispersing for 5 ~ 20 min in advance, adding the modified solution into a liquid storage tank of the V-shaped mixer, starting a spray switch, simultaneously starting a stirring switch of the V-shaped mixer, carrying out surface modification on the hollow ceramic powder dispersed in the cavity in a spray mode, continuously dispersing and stirring for 20 ~ 60 min after all liquid in the liquid storage tank is sprayed, taking out the hollow ceramic powder modified in the cavity of the V-shaped mixer after stirring is finished, drying for 2 ~ 6h in an oven at 100 ~ 120 ℃, and grinding and sieving to obtain the modified hollow ceramic powder;

(2) weighing modified hollow ceramic powder with the mass ratio of 10 ~ 50wt% and PTFE resin dispersion powder with the mass ratio of 50 ~ 90wt%, sequentially adding the modified hollow ceramic powder and the PTFE resin dispersion powder into a cavity of a V-shaped mixer, turning on a stirring switch, and fully mixing and stirring for 2 ~ 10 hours until the two material components are uniformly stirred;

(3) adding a certain mass of forming aid into a liquid storage tank of the V-shaped mixer, wherein the mass proportion of the forming aid is 5 ~ 30wt% of the total mass of the modified hollow ceramic powder and the PTFE resin dispersion powder, turning on a stirring switch, and continuously mixing for 2 ~ 10 h;

(4) curing, namely putting the mixed materials into a low-temperature oven, preserving the heat at 40 ~ 55 ℃ for 10 ~ 20 h, and curing the materials before molding;

(5) extruding and molding, namely putting the cured composite material into an extruder for extrusion molding, wherein the extrusion pressure is 10 ~ 70MPa, and the extrusion speed is 0.5 ~ 5 m/min, so as to obtain a cylindrical blank with the diameter of about 5 ~ 30 cm;

(6) rolling the cylindrical blank on a rolling machine repeatedly until the cylindrical blank becomes a raw substrate with the thickness of 0.2 ~ 2.0.0 mm;

(7) drying the rolled green substrate in a high temperature oven at 150 ~ 320 deg.c for 5 ~ 24 hr to eliminate organic additive;

(8) and (3) laminating and sintering, namely laminating the dried substrate according to the required thickness, covering copper foils on two sides, placing the substrate in a vacuum laminating machine for hot-pressing and sintering, wherein the hot-pressing temperature is 350 ~ 390 ℃, the pressure is 3 ~ 20MPa, the heat preservation time is 1 ~ 5h, and then naturally cooling to the room temperature to obtain the microwave dielectric substrate sample with the low dielectric constant.

2. The method according to claim 1, wherein the hollow ceramic powder is SiO with a hollow structure₂、Al₂O₃、TiO₂And perovskite ceramic powder or a mixture of two or more thereof.

3. The method according to claim 1, wherein the silane coupling agent is one or a mixture of two or more of phenyltrimethoxysilane, aminoethoxyaminopropyltrimethoxysilane, tridecafluorooctyloxysilane and heptadecafluorodecyltriethoxysilane.

4. The method according to claim 1, wherein the silane coupling agent is used in an amount of 0.1 ~ 1.0.0 wt% based on the mass of the hollow ceramic powder.

5. The method for preparing a low dielectric constant microwave dielectric substrate comprising hollow ceramic powder of claim 1, wherein the formic acid ethanol solution in the modifying solution is prepared from formic acid and absolute ethyl alcohol, wherein the mass ratio of formic acid to absolute ethyl alcohol is 1:1 ~ 1:6, the silane coupling agent accounts for 10: 10 ~ 60wt% of the total mass of the modifying solution, and the formic acid ethanol solution accounts for 40: 40 ~ 90wt% of the total mass of the modifying solution.

6. The method according to claim 1, wherein the forming aid is one or a mixture of two or more of mineral spirit, petroleum ether, paraffin oil and aviation kerosene.

7. The method of claim 1, wherein the copper foil is an electrolytic, rolled, low profile or ultra low profile copper foil having a thickness of 18 μm or 35 μm.

Technical Field

The invention relates to a microwave composite dielectric substrate manufacturing technology, in particular to a preparation method of a low-dielectric-constant microwave dielectric substrate containing hollow ceramic powder.

Background

With the rapid development of radio communication technology, the use frequency of high-frequency signal transmission and processing equipment is developed from 3G and 4G to 5G, which puts high requirements on the performance of high-frequency microwave composite dielectric materials, such as dielectric constant, dielectric loss, thermal expansion coefficient, water absorption, mechanical property, processability and the like. The microwave dielectric material with low dielectric constant is favorable for high-speed, low-delay and lossless transmission of microwave signals, and is widely applied to the key fields of ultrahigh-density and ultra-large-scale integrated circuits. The dielectric constant of air is 1, and proper air is introduced into the microwave dielectric material, so that the dielectric constant of the microwave dielectric material can be effectively reduced, the effective method is to introduce hollow ceramic powder as a filler, however, the traditional mixing mode can cause the phenomenon of uneven mixing due to different densities of the filler and organic resin, powder with high density is easy to accumulate at dead corners, filler with low density is easy to agglomerate in the material, and the traditional method for preparing the microwave dielectric substrate by mechanical mixing is not suitable for preparing the hollow ceramic powder filler substrate. In addition, the traditional mould pressing process is adopted to press the composite powder of PTFE and the filler into a substrate with a certain thickness, the thickness of the substrate is difficult to be accurately controlled, and the uniformity of the thickness of each part of the substrate is poor, so that the defects are more, and the requirements of the microwave circuit board cannot be met.

Disclosure of Invention

In view of the problems of the prior art, the invention aims to provide a method for preparing a low-dielectric-constant microwave dielectric substrate containing hollow ceramic powder. The invention adopts the V-shaped mixer, has uniform mixing, no material accumulation and high efficiency, and can realize uniform mixing of PTFE resin dispersed powder, hollow ceramic powder and forming auxiliary agent in the system; the method of combining extrusion and calendaring molding is adopted, and compared with the traditional die pressing process, the method for preparing the dielectric substrate has the advantages of high thickness accuracy, good uniformity, simple and convenient working procedure, strong operability and convenience for industrialization.

The technical scheme adopted by the invention is as follows: a method for preparing a low dielectric constant microwave dielectric substrate containing hollow ceramic powder comprises the following steps:

(1) the method comprises the steps of preparing a modified solution by adding a silane coupling agent into a formic acid ethanol solution according to a ratio, filling hollow ceramic powder with a certain mass into a cavity of equipment by using a V-shaped mixer, dispersing for 5 ~ 20 min in advance, adding the modified solution into a liquid storage tank of the V-shaped mixer, starting a spray switch, simultaneously starting a stirring switch of the V-shaped mixer, carrying out surface modification on the hollow ceramic powder dispersed in the cavity in a spraying mode, continuously dispersing and stirring for 20 ~ 60 min after all liquid in the liquid storage tank is sprayed, taking out the modified hollow ceramic powder in the cavity of the V-shaped mixer after stirring is finished, drying for 2 ~ 6h at 100 ~ 120 ℃ in an oven, and grinding and sieving to obtain the modified hollow ceramic powder.

(2) Weighing modified hollow ceramic powder with the mass ratio of 10 ~ 50wt% and PTFE resin dispersion powder with the mass ratio of 50 ~ 90wt%, sequentially adding the modified hollow ceramic powder and the PTFE resin dispersion powder into a cavity of a V-shaped mixer, turning on a stirring switch, and fully mixing and stirring for 2 ~ 10 hours until the two material components are uniformly stirred;

(3) adding a certain mass of forming aid into a liquid storage tank of the V-shaped mixer, wherein the mass proportion of the forming aid is 5 ~ 30wt% of the total mass of the modified hollow ceramic powder and the PTFE resin dispersion powder, turning on a stirring switch, and continuously mixing for 2 ~ 10 h;

(4) and curing, namely putting the mixed materials into a low-temperature oven, preserving the heat at 40 ~ 55 ℃ for 10 ~ 20 h, and curing the materials before molding.

(5) And (3) extrusion molding, namely putting the cured composite material into an extruder for extrusion molding, wherein the extrusion pressure is 10 ~ 70MPa, and the extrusion speed is 0.5 ~ 5 m/min, so that a cylindrical blank with the diameter of about 5 ~ 30cm is obtained.

(6) And rolling into sheet, namely repeatedly rolling the cylindrical blank on a rolling machine until the cylindrical blank becomes a raw substrate sheet with the thickness of 0.2 ~ 2.0.0 mm.

(7) And drying the substrate, namely putting the rolled green substrate into a high-temperature oven, drying the green substrate at the temperature of 150 ~ 320 ℃ for 5 ~ 24 h under the condition of vacuum or air blast, and removing organic additives in the material.

(8) And (3) laminating and sintering, namely laminating the dried substrate according to the required thickness according to the picture, covering copper foils on two sides, placing the substrate in a vacuum laminating machine for hot-pressing and sintering, wherein the hot-pressing temperature is 350 ~ 390 ℃, the pressure is 3 ~ 20MPa, the heat preservation time is 1 ~ 5h, and then naturally cooling to the room temperature to obtain the low-dielectric-constant microwave dielectric substrate sample.

The hollow ceramic powder is SiO with a hollow structure₂、Al₂O₃、TiO₂And perovskite ceramic powder or a mixture of two or more thereof.

The silane coupling agent is one or a mixture of more than two of phenyl trimethoxy silane, aminoethoxy aminopropyl trimethoxy silane, tridecafluorooctyl triethoxy silane and heptadecafluorodecyl triethoxy silane.

The dosage of the silane coupling agent is 0.1 ~ 1.0.0 wt% of the mass of the hollow ceramic powder.

The formic acid ethanol solution in the modified solution is prepared from formic acid and absolute ethyl alcohol, wherein the mass ratio of the formic acid to the absolute ethyl alcohol is 1:1 ~ 1:6, the silane coupling agent accounts for 10 ~ 60wt% of the total mass of the modified solution, and the formic acid ethanol solution accounts for 40 ~ 90wt% of the total mass of the modified solution.

The forming auxiliary agent is one or a mixture of more than two of solvent oil, petroleum ether, paraffin oil and aviation kerosene.

The copper foil of the invention has a thickness of 18 μm or 35 μm and is an electrolytic, rolled, low profile or ultra-low profile copper foil.

The beneficial effects produced by the invention are as follows: the filler adopted by the method is the ceramic powder with the hollow particles, and compared with the common solid particle ceramic powder, the particles of the hollow ceramic powder contain a certain proportion of air (the dielectric constant of the hollow ceramic powder is 1), so that the dielectric constant is successfully reduced to below 2.20, and the dielectric loss is lower than 0.0021. The microwave dielectric substrate with low dielectric constant is beneficial to low-delay and low-loss transmission of high-frequency signals, and is a potential base material for high-frequency and high-speed circuit boards.

Detailed Description

The invention is further illustrated by the following examples:

a method for preparing a low dielectric constant microwave dielectric substrate containing hollow ceramic powder comprises the following steps:

(1) surface modification: weighing phenyl trimethoxy silane which accounts for 0.3wt% of the hollow ceramic powder by mass as a coupling agent, weighing formic acid and absolute ethyl alcohol which are in a mass ratio of 1:5, mixing to obtain a formic acid ethyl alcohol solution, and adding the phenyl trimethoxy silane into the formic acid ethyl alcohol solution to prepare a modified solution, wherein the phenyl trimethoxy silane accounts for 35wt% of the total mass of the modified solution, and the formic acid ethyl alcohol solution accounts for 65wt% of the total mass of the modified solution. Adopting GHJ-200 type V type mixer, and charging 100 kg of SiO with hollow structure₂The method comprises the following steps of firstly dispersing ceramic powder for 15 min, then starting a spraying switch, simultaneously starting a stirring switch of a V-shaped mixer, carrying out surface modification on the dispersed hollow ceramic powder in a cavity in a spraying mode, and continuously dispersing and stirring for 30 min after all liquid in a liquid storage tank is completely sprayed; after stirring, taking out the modified hollow ceramic powder in the cavity of the V-shaped mixer, and drying for 4 hours in an oven at 110 ℃; and grinding and sieving to obtain the modified hollow ceramic powder.

(2) Mixing materials: weighing modified hollow ceramic powder with the mass ratio of 30wt% and PTFE resin dispersed powder with the mass ratio of 70wt%, sequentially adding the modified hollow ceramic powder and the PTFE resin dispersed powder into a cavity of a V-shaped mixer for mixing, opening a stirring switch, and fully mixing and stirring for 6 hours until the two material components are uniformly stirred.

(3) And (3) mixing auxiliary agents: adding a certain mass of forming aid into a liquid storage tank of a VH-300 type V-shaped mixer, wherein the forming aid is a mixture of paraffin oil and aviation kerosene (the mass ratio of the paraffin oil to the aviation kerosene is 1: 1), the mass ratio of the forming aid is 15wt% of the total mass of the modified hollow ceramic powder and the PTFE resin dispersion powder, turning on a stirring switch, and continuously mixing for 5 hours.

(4) Curing: and (3) putting the mixed material into an electrically heated forced air drying low-temperature oven, preserving the heat at 45 ℃ for 15 hours, and curing the material before molding.

(5) And (3) extrusion molding: and (3) putting the cured composite material into a plunger type extruder for extrusion molding, wherein the extrusion pressure is 30MPa, and the extrusion speed is 2 m/min, so that a cylindrical blank with the diameter of about 10 cm is obtained.

(6) Rolling into sheets: repeatedly calendering the cylindrical blank on a three-roller calender until the cylindrical blank becomes a raw substrate sheet with the thickness of 0.5 mm.

(7) Drying the substrate: and (3) placing the rolled green chip in an electrically heated forced air drying high-temperature oven, and drying at the temperature of 250 ℃ for 10 hours under the condition of air blowing to remove organic additives in the materials.

(8) And (3) lamination sintering: stacking two layers of substrates with the thickness of 0.5mm according to the required target thickness of 1.0mm, covering electrolytic copper foils with the thickness of 35 mu m on the two surfaces, placing the substrates in a vacuum laminating machine for hot pressing and sintering, wherein the hot pressing temperature is 370 ℃, the pressure is 10MPa, the heat preservation time is 2 h, and then naturally cooling to the room temperature to obtain the microwave dielectric substrate with the smooth and flat two surfaces and the low dielectric constant.

And (3) dielectric property test: cutting the low-dielectric-constant microwave dielectric substrate into a size required by testing, and testing the microwave dielectric property of the low-dielectric-constant microwave dielectric substrate, wherein the dielectric constant is 2.1686 at 10GHz, and the dielectric loss is 0.0012.