阅读说明：本技术 一种核壳结构复合粉前驱体及ltcc基板的制备方法 (Preparation method of core-shell structure composite powder precursor and LTCC substrate ) 是由 王君从 岳红维 吕旭涛 陈丹熠 刁手政 冯航 孙宇凯 张宏科 赵晓龙 王志浩 王 于 2020-08-17 设计创作，主要内容包括：本发明公开了一种核壳结构复合粉前驱体及LTCC基板的制备方法,属于LTCC技术领域。本发明方法借助核壳结构的设计思路,通过简单的溶胶凝胶方法制备出核壳结构的陶瓷-玻璃复合粉体,通过简单的混合过程和流延成型工艺,制备出陶瓷-玻璃复合薄坯,再通过裁片和叠压处理,通过低温烧结工艺制备出高性能的LTCC陶瓷基板。本方法所得到复合粉的粉体均匀性得到极大提高,制备的陶瓷基板性能优异,稳定性高,具有较高的推广应用价值。(The invention discloses a preparation method of a core-shell structure composite powder precursor and an LTCC substrate, and belongs to the technical field of LTCC. The method prepares the ceramic-glass composite powder with the core-shell structure by a simple sol-gel method with the help of the design idea of the core-shell structure, prepares a ceramic-glass composite thin blank by a simple mixing process and a tape casting process, and prepares the high-performance LTCC ceramic substrate by a low-temperature sintering process through cutting pieces and laminating treatment. The powder uniformity of the composite powder obtained by the method is greatly improved, and the prepared ceramic substrate has excellent performance, high stability and higher popularization and application values.)

1. A preparation method of a core-shell structure composite powder precursor is characterized by comprising the following steps:

(1) dissolving 5-15 wt% of calcium carbonate powder in HNO₃Preparing a nitric acid solution, then adding 5-15 wt% of boric acid, 1-10 wt% of lanthanum nitrate, europium nitrate or dysprosium nitrate and the nitric acid solution into H₂In O, stirring for 30-60 min in a water bath kettle at 25-60 ℃ to fully dissolve the solution, and then adding 40-60 wt% of alumina ceramic powder with the particle size of 0.1-20 mu m to prepare solution A;

(2) adding tetraethoxysilane into ethanol according to the mass ratio of 15-5: 1, and stirring in a water bath kettle for 30-60 min to prepare an ethanol solution of tetraethoxysilane, namely a solution B;

(3) slowly adding the solution A into the solution B dropwise while stirring quickly to enable the solution A and the solution B to react fully, and then adding nitric acid to adjust the pH value to 4.5-6.0;

(4) placing the mixed solution obtained in the step (3) in a water bath kettle at the temperature of 25-50 ℃ and stirring for 2-6 hours to obtain wet gel;

(5) naturally aging the wet gel for 24-36 h at normal temperature to gelatinize the wet gel;

(6) putting the aged wet gel into a drying oven, and drying for 16-24 h at the temperature of 100-150 ℃ to discharge the moisture;

(7) cooling the dried gel to room temperature, putting the gel into a ball mill, and grinding the gel into powder to obtain a ceramic-glass composite powder precursor with a core-shell structure; the rotating speed of the ball mill is 200 rpm/min-300 rpm/min, and the ball milling time is 6-24 h.

2. A preparation method of an LTCC substrate is characterized by comprising the following steps:

(1) placing the composite powder precursor obtained in the claim 1 into a resistance furnace, gradually heating to 100-140 ℃ at a heating rate of 0.5-1.5 ℃/min, and then keeping the temperature for 60-120 min to fully volatilize water and ethanol; then gradually heating to 300-360 ℃ at a heating rate of 0.5-1.5 ℃/min, and preserving heat for 60-120 min to decompose and volatilize residual organic matters and realize the glass phase of the composite powder; then cooling along with the furnace to obtain core-shell structure ceramic-glass composite powder;

(2) slowly adding absolute ethyl alcohol and methylbenzene into a grinding tank according to the weight ratio of 1-2: 1, adding fish oil accounting for 0.2-1% of the total weight of the absolute ethyl alcohol and the methylbenzene into the grinding tank by using a liquid transfer gun, weighing ceramic-glass composite powder accounting for 40-65% of the total weight of the absolute ethyl alcohol and the methylbenzene, adding the ceramic-glass composite powder into the grinding tank, and performing ball milling and mixing, wherein the ball milling rotation speed is 250-350 rpm/min, and the ball milling time is 6-12 h; then adding a butyl phthalate plasticizer which is 10-20% of the total weight of absolute ethyl alcohol and toluene, and continuing ball milling for 6-12 h; then adding a PVB binder accounting for 1-5% of the total weight of the absolute ethyl alcohol and the methylbenzene, and continuing ball milling for 6-12 hours to obtain slurry for tape casting; carrying out vacuum treatment on the slurry, then carrying out tape casting treatment on the slurry after the vacuum treatment on a tape casting machine, wherein the tape casting speed is 0.1-0.5 m/min, the front cutter height is controlled to be 0.1-0.5 mm, the rear cutter speed is controlled to be 0.1-0.4 mm, and drying at room temperature to obtain tape casting biscuit sheets;

(3) and (3) carrying out cutting and isostatic pressing on the tape casting biscuit sheet, and then placing the tape casting biscuit sheet in a box type resistance furnace for sintering to obtain the LTCC substrate.

3. The method of claim 1, wherein the sintering schedule in step (3) is as follows: heating to 500-600 ℃ at a heating rate of 2-8 ℃/min, and keeping the temperature for 10-60 min; then heating to 700-950 ℃ at a heating rate of 1-5 ℃/min, and keeping the temperature for 60-240 min.

Technical Field

The invention relates to the technical fields of electronic devices, communication, packaging, ceramic materials, LTCC and the like, in particular to a preparation method of a core-shell structure composite powder precursor and an LTCC substrate.

Background

With the continuous development of modern wireless communication technology, microwave communication components have become the most important parts. Meanwhile, with the rapid development of 5G, microwave electronic products, wearable electronic devices, satellite communication systems, and medical electronic devices, microwave communication components tend to have more miniaturized structures, higher integration density, faster transmission rate, and higher reliability, which puts high demands on packaging materials and also puts more strict physical and chemical stability demands on packaging processes. In the realization of miniaturization, integration, lightness and multifunction of electronic devices, Low temperature co-fired Ceramic (LTCC) is one of the most widely applied technical methods so far. It was originally applied in the field of military equipment, but LTCC has been widely used in the fields of automotive electronics, communications, medical equipment, and the like. Currently, the LTCC substrate in practical application is only a material system developed by West national manufacturers such as Murata and Kyocera for years. China still stays behind in the field, and further research on the problems of the related materials of the LTCC substrate is beneficial to promoting the further development of the LTCC technology.

Currently, the common system for preparing LTCC ceramic substrates is a composite system of ceramic + glass phase. In the conventional preparation, ceramic powder and glass powder are subjected to mechanical ball milling for a long time and then are supplemented with other plasticizers, binders and dispersants to achieve the effect of uniform dispersion. However, the micro-inhomogeneity of the ceramic powder and the glass powder in the slurry system still exists, which affects the homogeneity of the ceramic thin blank prepared by tape casting, and then affects the sintering property of the low-temperature co-fired ceramic substrate material and the stability of the dielectric property and the like thereof. Therefore, a need exists in the art for a novel powder and a corresponding LTCC preparation method that can solve such micro-inhomogeneity.

Disclosure of Invention

In order to solve the problems in the prior art, the invention discloses a preparation method of a core-shell structure composite powder precursor and an LTCC substrate.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method of a core-shell structure composite powder precursor comprises the following steps:

(1) dissolving 5-15 wt% of calcium carbonate powder in HNO₃Preparing a nitric acid solution, then adding 5-15 wt% of boric acid, 1-10 wt% of lanthanum nitrate, europium nitrate or dysprosium nitrate and the nitric acid solution into H₂In O, stirring for 30-60 min in a water bath kettle at 25-60 ℃ to fully dissolve the solution, and then adding 40-60 wt% of alumina ceramic powder with the particle size of 0.1-20 mu m to prepare solution A;

(2) adding tetraethoxysilane into ethanol according to the mass ratio of 15-5: 1, and stirring in a water bath kettle for 30-60 min to prepare an ethanol solution of tetraethoxysilane, namely a solution B;

(3) slowly adding the solution A into the solution B dropwise while stirring quickly to enable the solution A and the solution B to react fully, and then adding nitric acid to adjust the pH value to 4.5-6.0;

(4) placing the mixed solution obtained in the step (3) in a water bath kettle at the temperature of 25-50 ℃ and stirring for 2-6 hours to obtain wet gel;

(5) naturally aging the wet gel for 24-36 h at normal temperature to gelatinize the wet gel;

(6) putting the aged wet gel into a drying oven, and drying for 16-24 h at the temperature of 100-150 ℃ to discharge the moisture;

(7) cooling the dried gel to room temperature, putting the gel into a ball mill, and grinding the gel into powder to obtain a ceramic-glass composite powder precursor with a core-shell structure; the rotating speed of the ball mill is 200 rpm/min-300 rpm/min, and the ball milling time is 6-24 h.

In addition, the invention also provides a preparation method of the LTCC substrate, which comprises the following steps:

(1) placing the composite powder precursor obtained in the claim 1 into a resistance furnace, gradually heating to 100-140 ℃ at a heating rate of 0.5-1.5 ℃/min, and then keeping the temperature for 60-120 min to fully volatilize water and ethanol; then gradually heating to 300-360 ℃ at a heating rate of 0.5-1.5 ℃/min, and preserving heat for 60-120 min to decompose and volatilize residual organic matters and realize the glass phase of the composite powder; then cooling along with the furnace to obtain core-shell structure ceramic-glass composite powder;

(2) slowly adding absolute ethyl alcohol and methylbenzene into a grinding tank according to the weight ratio of 1-2: 1, adding fish oil accounting for 0.2-1% of the total weight of the absolute ethyl alcohol and the methylbenzene into the grinding tank by using a liquid transfer gun, weighing ceramic-glass composite powder accounting for 40-65% of the total weight of the absolute ethyl alcohol and the methylbenzene, adding the ceramic-glass composite powder into the grinding tank, and performing ball milling and mixing, wherein the ball milling rotation speed is 250-350 rpm/min, and the ball milling time is 6-12 h; then adding a butyl phthalate plasticizer which is 10-20% of the total weight of absolute ethyl alcohol and toluene, and continuing ball milling for 6-12 h; then adding a PVB binder accounting for 1-5% of the total weight of the absolute ethyl alcohol and the methylbenzene, and continuing ball milling for 6-12 hours to obtain slurry for tape casting; carrying out vacuum treatment on the slurry, then carrying out tape casting treatment on the slurry after the vacuum treatment on a tape casting machine, wherein the tape casting speed is 0.1-0.5 m/min, the front cutter height is controlled to be 0.1-0.5 mm, the rear cutter speed is controlled to be 0.1-0.4 mm, and drying at room temperature to obtain tape casting biscuit sheets;

(3) and (3) carrying out cutting and isostatic pressing on the tape casting biscuit sheet, and then placing the tape casting biscuit sheet in a box type resistance furnace for sintering to obtain the LTCC substrate.

Further, the sintering schedule in the step (3) is as follows: heating to 500-600 ℃ at a heating rate of 2-8 ℃/min, and keeping the temperature for 10-60 min; then heating to 700-950 ℃ at a heating rate of 1-5 ℃/min, and keeping the temperature for 60-240 min.

The beneficial effects obtained by the invention are as follows:

(1) the invention adopts a simple sol-gel process to deposit a layer of rare earth glass powder on the surface of the ceramic powder, and the components of the glass powder can be effectively designed and controlled.

(2) The ceramic-glass composite powder with the core-shell structure takes the ceramic phase as the core and the glass phase as the shell, so that the uniformity of the powder is greatly improved, and the prepared ceramic substrate has excellent performance, high stability and higher popularization and application values.

Drawings

Fig. 1 is a process flow diagram of a method for manufacturing an LTCC substrate according to an embodiment of the invention.

Detailed Description

The technical solution of the present invention is further explained with reference to the accompanying drawings and the detailed description.

As shown in fig. 1, a method for preparing an LTCC substrate includes the following steps:

(1) preparing a core-shell structure composite powder precursor:

firstly, dissolving a certain amount (5-15 wt%) of calcium carbonate powder in HNO₃Then weighing a certain amount (1-10 wt%) of lanthanum nitrate, europium nitrate or dysprosium nitrate and a certain amount (5-15 wt%) of boric acid, and using H together with a nitric acid solution₂Putting O as a solvent into a water bath kettle at the temperature of 25-60 ℃ and stirring for 30-60 min for fully dissolving; then, adding a certain amount (40-60 wt%) of alumina ceramic powder with the particle size of 0.1-20 μm to prepare solution A;

secondly, tetraethoxysilane Si (OC) is added according to the mass ratio of (15: 1-5: 1)₂H₅)₄With ethanol C₂H₆O to Si (OC)₂H₅)₄C of (A)₂H₆Stirring the O solution in a water bath kettle for 30-60 min to obtain a B solution;

then, dropwise and slowly adding the solution A into the solution B, simultaneously stirring quickly to enable the solution A and the solution B to react fully, stirring for 30-60 min, and adding nitric acid to adjust the pH value to be about 4.5-6.0; placing the mixed solution in a water bath kettle at 25-50 ℃ and stirring for 2-6 h to obtain wet gel; naturally aging the obtained wet gel for 24-36 h at normal temperature to gelatinize the wet gel; putting the aged wet gel into a drying oven, and drying for 16-24 hours at 100-150 ℃ to discharge the moisture; and cooling the dried gel to room temperature, putting the gel into a ball mill, and grinding the gel into powder, wherein the rotating speed is 200-300 rpm/min, and the ball milling time is 6-24 h, so as to obtain the core-shell structure composite powder precursor.

(2) Heat treatment of core-shell structure powder:

and (3) putting the obtained composite powder precursor into a resistance furnace, heating to 100-140 ℃, heating at a rate of 0.5-1.5 ℃/min, and keeping the temperature for 60-120 min to fully volatilize water and ethanol. And then heating to 300-360 ℃, keeping the temperature at the rate of 0.5-1.5 ℃/min for 60-120 min, decomposing and volatilizing residual organic matters, and cooling along with the furnace to obtain the composite powder realizing the glass phase.

(3) Preparing a biscuit sheet by adopting a tape casting process:

firstly, taking a certain amount of absolute ethyl alcohol and toluene according to the ratio of 1: 1-2: 1, and slowly adding the absolute ethyl alcohol and the toluene into a grinding tank; adding fish oil accounting for 0.2-1% of the total amount of the absolute ethyl alcohol and the methylbenzene into a grinding tank by using a liquid transfer gun; weighing composite powder with the total amount of absolute ethyl alcohol and toluene being 40-65% and adding the composite powder into a grinding tank; ball-milling and mixing the mixture in the grinding tank, wherein the rotating speed is 250 rpm/min-350 rpm/min, and the ball-milling time is 6 h-12 h; adding butyl phthalate plasticizer (the weight is 10% -20% of the total weight of the absolute ethyl alcohol and the toluene), continuing ball milling for 6-12 h, adding PVB binder (the weight is 1% -5% of the total weight of the absolute ethyl alcohol and the toluene), and continuing ball milling for 6-12 h to obtain slurry for tape casting; and then carrying out tape casting treatment on the slurry subjected to vacuum treatment on a tape casting machine, wherein the tape casting speed is 0.1-0.5 m/min, the front cutter height is controlled to be 0.1-0.5 mm, the rear cutter speed is controlled to be 0.1-0.4 mm, and the tape casting blank sheet can be obtained after drying at room temperature.

(4) Low-temperature co-firing:

and (3) carrying out cutting and isostatic pressing on the tape casting biscuit sheet, and sintering in a box-type resistance furnace. The sintering system is as follows: heating to 500-600 ℃ at a heating rate of 2-8 ℃/min, and keeping the temperature for 10-60 min; and then heating to 700-950 ℃ at a heating rate of 1-5 ℃/min, and preserving the heat for 60-240 min to finally prepare the high-performance LTCC low-temperature co-fired ceramic substrate.

In the method, the design idea of the core-shell structure composite powder provides a way for improving the uniformity of the LTCC composite system. Particularly, the core-shell structure is realized by taking ceramic powder as a core and glass powder as a shell, so that the uniformity of the ceramic core-shell structure is realized from the raw material design angle, the difficulty of the raw material mixing process is greatly reduced, the formability and the performance stability of the casting biscuit are improved, and the sintering stability of the whole ceramic substrate material is favorably improved.

Some more specific examples are as follows: