A soft composite silicon powder with low hardness and controllable thermal expansion and an electronic packaging material

Abstract

This invention relates to the field of electronic materials technology, specifically to a soft composite silicon micropowder with low hardness and controllable thermal expansion, and an electronic packaging material. The soft composite silicon micropowder comprises the following raw materials in parts by weight: silica: 50.0~90.0 parts; limestone: 1.0~20.0 parts; feldspar: 1.0~15.0 parts; borosilicate: 0.0~10.0 parts; magnesite: 0.0~10.0 parts; fluorite: 0.0~5.0 parts; apatite: 0.0~5.0 parts. This invention achieves independent control and synergistic optimization of hardness and thermal expansion coefficient through the synergistic adjustment of multiple components. The resulting product has low Mohs hardness and a controllable thermal expansion coefficient, and can be widely used in electronic packaging, rubber and plastic functional materials, and other fields.

Description

Technical Field

[0001] This invention relates to the field of electronic materials technology, specifically to a soft composite silicon micropowder with low hardness and controllable thermal expansion and an electronic packaging material. Background Technology

[0002] With the rapid development of 5G communication, high-frequency and high-speed electronic equipment, and chip packaging technology, copper-clad laminates (CCLs), as the core material for electronic circuit boards, face increasingly stringent performance requirements. Flexible composite silicon powder (also known as flexible glass powder), as an important functional filler in CCLs, plays a crucial role in reducing the coefficient of thermal expansion, improving dimensional stability, and enhancing processing performance. Traditional flexible composite silicon powders are mostly glass-based powders, which often struggle to simultaneously meet the "dual low" requirements of low hardness and low coefficient of thermal expansion in CCL applications.

[0003] In the field of fillers for copper-clad laminates, there are related patent reports on soft glass micropowder and silicon micropowder with low coefficient of thermal expansion. CN102942304A prepared a soft glass micropowder for copper-clad laminates by introducing B2O3 into the SiO2-Al2O3-CaO system. It has low hardness and can reduce the wear of drilling tools. CN103304143A further introduced a large amount of BaO into the above-mentioned patent composition system to further reduce the material hardness. However, neither of the above two patents designed and controlled the coefficient of thermal expansion, and the resulting soft glass powder has a high coefficient of thermal expansion, which is difficult to meet the dimensional stability requirements of copper-clad laminates. On the other hand, CN101280125B discloses a method for preparing electronic-grade ultrafine silicon micropowder for copper-clad laminates with low coefficient of thermal expansion. It uses high-purity quartz sand with a SiO2 content of not less than 99.8% as raw material, and is prepared by magnetic separation, ball milling, precision classification and surface modification. It has a low coefficient of thermal expansion and good dimensional stability. However, high-purity quartz sand has a Mohs hardness close to 7, which causes severe tool wear during copper-clad laminate drilling, making it difficult to guarantee machining accuracy.

[0004] Therefore, the main problem currently facing flexible composite silicon micropowders is that while reducing hardness, the coefficient of thermal expansion will increase accordingly, or while maintaining a low coefficient of thermal expansion, the hardness will be relatively high. It is difficult to achieve both low hardness and low expansion in flexible composite silicon micropowders. In order to meet the application requirements of electronic packaging and other rubber and plastic functional materials, it is urgent to develop a new type of low-hardness flexible composite silicon micropowder that can control the coefficient of thermal expansion without increasing or reduce the coefficient of thermal expansion at the same time while reducing hardness. Summary of the Invention

[0005] In view of this, the purpose of this invention is to at least partially solve one of the technical problems in the related art. To this end, this invention provides a soft composite silica micropowder with low hardness and controllable thermal expansion. This invention uses silica as the main raw material and introduces other mineral or chemical raw materials to construct a novel glass frit composition system of SiO2-CaO-Al2O3-B2O3-MgO-X. Through the synergistic regulation of the glass network structure by the SiO2-CaO-Al2O3-B2O3-MgO-X multi-component system, independent optimization of hardness and thermal expansion coefficient is achieved, solving the industry problem of "difficulty in simultaneously achieving low hardness and low expansion".

[0006] To solve the above-mentioned technical problems, the present invention is implemented as follows:

[0007] According to one aspect of the present invention, a soft composite silicon micropowder with low hardness and controllable thermal expansion is provided, the soft composite silicon micropowder comprising the following raw materials in parts by weight:

[0008] Silica: 50.0~90.0 parts;

[0009] Limestone: 1.0~20.0 parts;

[0010] Feldspar: 1.0~15.0 parts;

[0011] Boronite: 0.0~10.0 parts;

[0012] Magnesite: 0.0~10.0 parts;

[0013] Fluorite: 0.0~5.0 parts;

[0014] Apatite: 0.0~5.0 parts.

[0015] In some embodiments, the flexible composite silicon micropowder comprises the following raw materials in parts by weight:

[0016] Silica: 65.0~85.0 parts;

[0017] Limestone: 5.0~18.0 parts;

[0018] Feldspar: 3.0~12.0 parts;

[0019] Boronite: 0.5~8.0 parts;

[0020] Magnesite: 1.0~8.0 parts;

[0021] Fluorite: 0.1~4.0 parts;

[0022] Apatite: 0.1~3.0 parts.

[0023] In some embodiments, the soft composite silica powder satisfies the following conditions: Mohs hardness 4-6, coefficient of thermal expansion 2.0 × 10⁻⁶. -6 / K~8.0×10 -6 / K, particle size distribution D50 is 0.5 μm ~ 6.0 μm.

[0024] In some embodiments, the soft composite silica powder satisfies the following conditions: Mohs hardness 4.5~5.5, coefficient of thermal expansion 3.0×10⁻⁶. -6 / K~6.0×10 -6 / K, particle size distribution D50 is 1.0 μm ~ 5.0 μm.

[0025] According to another aspect of the present invention, the present invention also provides a method for preparing the above-mentioned flexible composite silica powder, comprising the following steps:

[0026] (1) Mix the raw materials to obtain the batch;

[0027] (2) Melt the batch material from step (1) to obtain glass melt; then roll or quench it in water to obtain basic glass frit material;

[0028] (3) The basic glass frit material from step (2) is dried, ball-milled, air-jet pulverized and classified in sequence to obtain soft composite silicon micro powder.

[0029] In some of these implementations, the mixing time in step (1) is 3.0-60.0 min.

[0030] In some of these embodiments, the melting process in step (2) includes melting at 1400-1650°C for 0.5-8.0 h.

[0031] In some of these embodiments, the ball milling time in step (3) is 0.5 to 6.0 h.

[0032] In some of these embodiments, the time for air jet pulverization in step (3) is 0.5 to 4.0 h.

[0033] In some of these implementations, the mixing time in step (1) is 5.0 to 60.0 min.

[0034] In some of these embodiments, the melting process in step (2) includes: 1450~1600℃, and a holding time of 1.0~6.0 h.

[0035] In some of these embodiments, the ball milling time in step (3) is 1.0 to 5.0 h.

[0036] In some of these embodiments, the time for airflow pulverization in step (3) is 1.0 to 3.0 h.

[0037] According to another aspect of the present invention, the present invention also provides an inorganic filler, wherein the inorganic filler comprises the above-described soft composite silicon micro powder or the soft composite silicon micro powder prepared by the above-described preparation method.

[0038] According to another aspect of the present invention, the present invention also provides the application of the above-mentioned inorganic filler in electronic packaging materials, rubber and plastic functional materials, and copper clad laminate fillers.

[0039] According to another aspect of the present invention, the present invention also provides an electronic packaging material comprising the above-described flexible composite silicon micropowder or the flexible composite silicon micropowder prepared by the above-described preparation method.

[0040] This invention achieves independent control and synergistic optimization of hardness and coefficient of thermal expansion through the synergistic regulation of multiple components. The resulting product has low Mohs hardness and a controllable coefficient of thermal expansion, and can be widely used in fields such as electronic packaging and functional rubber and plastic materials. Specifically:

[0041] Regarding hardness control, Ca 2+ and Mg 2+ By breaking the Si-O-Si bonds, the glass network is depolymerized, reducing network constraint and thus lowering the material's hardness. The Mohs hardness can be controlled within the range of 4 to 6 by adjusting the CaO and MgO content. Some of the MgO... 2+ It may participate in network connections in the form of [MgO4] tetrahedra, which has a certain structural reinforcement effect, but its overall effect is still mainly to reduce hardness.

[0042] Regarding the control of thermal expansion coefficient, Al 3+ B2O3 participates in network construction in the form of [AlO4] tetrahedra, enhancing the network structure; when introduced in appropriate amounts, B2O3 exists in the form of [BO4] tetrahedra, increasing the degree of network cross-linking. By promoting the formation of the above tetrahedral coordination structures, network cross-linking is enhanced, thereby controlling the coefficient of thermal expansion to 3.0 × 10⁻⁶. -6 / K~6.0×10 -6 Within the range of / K.

[0043] Implementing the technical solution of the present invention has at least the following beneficial effects:

[0044] (1) The present invention achieves synergistic control of hardness and coefficient of thermal expansion, resulting in excellent overall product performance.

[0045] The method for preparing flexible composite silicon micropowder provided by this invention achieves synergistic control of hardness and coefficient of thermal expansion by constructing a multi-component oxide system and through the synergistic regulation of the multi-component components. The resulting flexible composite silicon micropowder has a Mohs hardness of 4-6, which is 30% lower than that of traditional flexible composite silicon micropowder (Mohs hardness 6); the coefficient of thermal expansion is stably controlled at 3.0 × 10⁻⁶. -6 / K~6.0×10 -6 Within the range of / K, it can be used as a functional inorganic filler in copper clad laminates, electronic packaging materials, underfill adhesives, electronic potting compounds, liquid sealing materials, adhesives, functional coatings, silicone rubber sealants, and some polymer composite materials.

[0046] (2) The present invention has a simple process, low cost, and is environmentally friendly, and has significant industrialization advantages.

[0047] The preparation method provided by this invention has a simple process flow and is easy to industrialize; the raw materials used are all conventional mineral raw materials such as silica, limestone, and feldspar, and do not involve expensive materials such as high-purity quartz sand and rare earth compounds, so the raw material cost is low; the entire preparation process does not use organic solvents, is environmentally friendly, and conforms to the concept of green manufacturing.

[0048] (3) The process of this invention is flexible and controllable, and the product consistency is good, making it suitable for large-scale promotion and application.

[0049] The preparation method provided by this invention has good process scalability and parameter adjustability. By adjusting the raw material ratio, melting regime and powder processing technology, the properties of the final product such as hardness, coefficient of thermal expansion and particle size distribution can be precisely controlled. The performance optimization window is wide, the batch stability of the product is good, and it is suitable for wide-scale application.

[0050] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0051] Figure 1 Photograph of the soft composite silica powder prepared in Example 1. Detailed Implementation

[0052] The present application will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present application.

[0053] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges or individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0054] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.

[0055] Unless otherwise specified, the terms "comprising" and "including" as used in this invention can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0056] Unless otherwise specified, all embodiments and optional embodiments of the present invention can be combined with each other to form new technical solutions.

[0057] Unless otherwise specified, all technical features and optional technical features of this invention can be combined to form new technical solutions.

[0058] Currently, the inventors of this invention have discovered during the research and development process that the main problem currently faced by soft composite silicon micropowder is that while reducing hardness, the coefficient of thermal expansion will increase accordingly, or while maintaining a low coefficient of thermal expansion, the hardness is relatively high. It is difficult to achieve both low hardness and low expansion in soft composite silicon micropowder.

[0059] Based on this, the inventors of this invention achieved independent control and synergistic optimization of hardness and coefficient of thermal expansion through the synergistic adjustment of multiple components. The resulting product has low Mohs hardness and a controllable coefficient of thermal expansion, and can be widely used in fields such as electronic packaging and functional rubber and plastic materials. Specifically, this invention adopts the following technical solution:

[0060] According to one aspect of the present invention, a soft composite silicon micropowder with low hardness and controllable thermal expansion is provided, the soft composite silicon micropowder comprising the following raw materials in parts by weight:

[0061] Silica: 50.0~90.0 parts;

[0062] Limestone: 1.0~20.0 parts;

[0063] Feldspar: 1.0~15.0 parts;

[0064] Boronite: 0.0~10.0 parts;

[0065] Magnesite: 0.0~10.0 parts;

[0066] Fluorite: 0.0~5.0 parts;

[0067] Apatite: 0.0~5.0 parts.

[0068] All raw materials used in this invention are industrial-grade natural mineral powders, eliminating the need for high-purity quartz sand or rare earth compounds, resulting in significantly lower costs compared to existing high-end fillers.

[0069] In some embodiments, the flexible composite silicon micropowder comprises the following raw materials in parts by weight:

[0070] Silica: 65.0~85.0 parts;

[0071] Limestone: 5.0~18.0 parts;

[0072] Feldspar: 3.0~12.0 parts;

[0073] Boronite: 0.5~8.0 parts;

[0074] Magnesite: 1.0~8.0 parts;

[0075] Fluorite: 0.1~4.0 parts;

[0076] Apatite: 0.1~3.0 parts.

[0077] In some embodiments, the soft composite silica powder satisfies the following conditions: Mohs hardness 4-6, coefficient of thermal expansion 2.0 × 10⁻⁶. -6 / K~8.0×10 -6 / K, particle size distribution D50 is 0.5 μm ~ 6.0 μm.

[0078] In some embodiments, the soft composite silica powder satisfies the following conditions: Mohs hardness 4.5~5.5, coefficient of thermal expansion 3.0×10⁻⁶. -6 / K~6.0×10 -6 / K, particle size distribution D50 is 1.0 μm ~ 5.0 μm.

[0079] According to another aspect of the present invention, the present invention also provides a method for preparing the above-mentioned flexible composite silica powder, comprising the following steps:

[0080] (1) Mix the raw materials to obtain the batch;

[0081] (2) Melt the batch material from step (1) to obtain glass melt; then roll or quench it in water to obtain basic glass frit material;

[0082] (3) The basic glass frit material from step (2) is dried, ball-milled, air-jet pulverized and classified in sequence to obtain soft composite silicon micro powder.

[0083] In some of these implementations, the mixing time in step (1) is 3.0 to 60.0 min.

[0084] In some of these embodiments, the melting process in step (2) includes melting at 1400~1650℃ for 0.5~8.0h.

[0085] In some of these embodiments, the ball milling time in step (3) is 0.5 to 6.0 h.

[0086] In some of these embodiments, the time for air jet pulverization in step (3) is 0.5 to 4.0 h.

[0087] In some of these implementations, the mixing time in step (1) is 5.0 to 60.0 min.

[0088] In some of these embodiments, the melting process in step (2) includes: 1450~1600℃, and a holding time of 1.0~6.0 h.

[0089] In some of these embodiments, the ball milling time in step (3) is 1.0 to 5.0 h.

[0090] In some of these embodiments, the time for airflow pulverization in step (3) is 1.0 to 3.0 h.

[0091] According to another aspect of the present invention, the present invention also provides an inorganic filler, wherein the inorganic filler comprises the above-described soft composite silicon micro powder or the soft composite silicon micro powder prepared by the above-described preparation method.

[0092] According to another aspect of the present invention, the present invention also provides the application of the above-mentioned inorganic filler in electronic packaging materials, rubber and plastic functional materials, and copper clad laminate fillers.

[0093] According to another aspect of the present invention, the present invention also provides an electronic packaging material comprising the above-described flexible composite silicon micropowder or the flexible composite silicon micropowder prepared by the above-described preparation method.

[0094] The present application will be described in detail below with reference to the accompanying drawings and embodiments. However, the implementation and protection of the present invention are not limited thereto. The following embodiments are only some embodiments of the present application and are not intended to limit the present application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0095] The raw materials used in this embodiment are as follows: Silica: SiO2 content ≥98%, produced in Donghai, Jiangsu, 80 mesh; Limestone: CaCO3 content ≥97%, produced in Guilin, Guangxi, 80 mesh; Feldspar: Al2O3 content ≥18%, produced in Inner Mongolia, 80 mesh; Magnesite: MgO content ≥45%, produced in Yingkou, Liaoning, 80 mesh; Boromacite: MgO·B2O3 content ≥60%, produced in Kuandian, Liaoning, 80 mesh; Fluorite: CaF2 content ≥85%, produced in Wuyi, Zhejiang, 80 mesh; Apatite: P2O5 content ≥28%, produced in Kaiyang, Guizhou, 80 mesh.

[0096] Example 1

[0097] A method for preparing a soft composite silica powder with low hardness and controllable thermal expansion includes the following steps:

[0098] (1) Weigh the raw materials according to the following weight parts: 74.4 parts silica, 12.5 parts limestone, 5.5 parts feldspar, 9.4 parts magnesite, 2.0 parts boromagnesite, 1.2 parts fluorite, and 1.0 parts apatite; mix the above raw materials in a mixer for 60.0 min to obtain the batch material;

[0099] (2) The batch material from step (1) is melted in a high-temperature furnace and completely reacted during the high-temperature melting process at 1580℃ to form a glass melt, and kept at the temperature for 6.0 h; the glass melt is obtained, and the basic glass frit material is obtained after water quenching and molding.

[0100] (3) The basic glass frit material was dried, ball-milled for 5.0 h, air-jet milled for 4.0 h, and then classified to obtain powder with an average particle size (D50) of 3 μm.

[0101] Example 2

[0102] A method for preparing a soft composite silica powder with low hardness and controllable thermal expansion includes the following steps:

[0103] (1) Weigh the raw materials according to the following weight parts: 73.4 parts silica, 12.5 parts limestone, 5.5 parts feldspar, 9.4 parts magnesite, 1.0 part borosilicate, 1.2 parts fluorite, and 1.0 part apatite; mix the above raw materials in a mixer for 60.0 min to obtain the batch material;

[0104] (2) The batch material is placed in a frit furnace and melted at 1560℃ for 7.0 h to obtain a uniform glass melt; the glass melt is water-quenched and shaped to obtain a basic glass frit material;

[0105] (3) After drying the basic glass frit, it was ball-milled for 6.0 h and air-flow milled for 4.0 h, and then classified to obtain soft composite silica powder with an average particle size (D50) of 3 μm.

[0106] Example 3

[0107] A method for preparing a soft composite silica powder with low hardness and controllable thermal expansion includes the following steps:

[0108] (1) Weigh the raw materials according to the following weight parts: 72.4 parts silica, 12.5 parts limestone, 5.5 parts feldspar, 9.4 parts magnesite, 2.0 parts boromagnesite, 1.2 parts fluorite, and 1.0 parts apatite; mix the above raw materials in a mixer for 30.0 min to obtain the batch material;

[0109] (2) The batch material is placed in a frit furnace and melted at 1540℃ and held for 6.0 h to obtain a uniform glass melt; the glass melt is water-quenched and shaped to obtain a basic glass frit material;

[0110] (3) After drying the base glass frit, it is ball-milled for 2.0 h and air-flow milled for 4.0 h, and then classified to obtain soft composite silica powder with an average particle size (D50) of 3 μm.

[0111] Example 4

[0112] A method for preparing a soft composite silica powder with low hardness and controllable thermal expansion includes the following steps:

[0113] 1) Weigh the raw materials according to the following weight parts: 71.4 parts silica, 12.5 parts limestone, 5.5 parts feldspar, 9.4 parts magnesite, 3.0 parts boromagnesite, 1.2 parts fluorite, and 1.0 part apatite; mix the above raw materials in a mixer for 60.0 min to obtain the batch material;

[0114] 2) Place the batch material in a frit furnace and melt it at 1520℃, hold it at that temperature for 0.5 h to obtain a homogeneous glass melt; the glass melt is then water-quenched and shaped to obtain the basic glass frit material;

[0115] 3) After drying, the base glass frit material is ball-milled for 0.5 h and air-jet milled for 4.0 h, and then classified to obtain soft composite silica powder with an average particle size (D50) of 3 μm.

[0116] Example 5

[0117] A method for preparing a soft composite silica powder with low hardness and controllable thermal expansion includes the following steps:

[0118] 1) Weigh the raw materials according to the following weight parts: 70.4 parts silica, 12.5 parts limestone, 5.5 parts feldspar, 9.4 parts magnesite, 4.0 parts borosilicate, 1.2 parts fluorite, and 1.0 part apatite; mix the above raw materials in a mixer for 60.0 min to obtain the batch material;

[0119] 2) The batch material is placed in a frit furnace and melted at 1500℃ for 4.0 h to obtain a homogeneous glass melt; the glass melt is then water-quenched and shaped to obtain the basic glass frit material;

[0120] 3) After drying, the basic glass frit material is ball-milled for 6.0 h and air-jet milled for 4.0 h, and then classified to obtain soft composite silica powder with an average particle size (D50) of 3 μm.

[0121] Example 6

[0122] The raw materials were weighed in the following proportions by weight: 69.4 parts silica, 12.5 parts limestone, 5.5 parts feldspar, 9.4 parts magnesite, 5.0 parts boromagnesite, 1.2 parts fluorite, and 1.0 part apatite. The above raw materials were mixed in a mixer for 60.0 min to obtain the batch. The remaining steps were the same as in Example 1.

[0123] Example 7

[0124] The raw materials were weighed in the following proportions by weight: 68.4 parts silica, 12.5 parts limestone, 5.5 parts feldspar, 9.4 parts magnesite, 6.0 parts boromagnesite, 1.2 parts fluorite, and 1.0 part apatite. The above raw materials were mixed in a mixer for 60.0 min to obtain the batch. The remaining steps were the same as in Example 1.

[0125] Example 8

[0126] The raw materials were weighed according to the following weight parts: 67.4 parts silica, 12.5 parts limestone, 5.5 parts feldspar, 9.4 parts magnesite, 7.0 parts boromagnesite, 1.2 parts fluorite, and 1.0 part apatite. The above raw materials were mixed in a mixer for 60.0 min to obtain the batch. The remaining steps were the same as in Example 1.

[0127] Comparative Example 1 (Commercially available soft glass powder)

[0128] Purchased conventional copper-clad laminate soft glass powder, without B2O3-MgO synergistic regulation.

[0129] Comparative Example 2 (High-purity quartz silica micro powder)

[0130] SiO2 ≥ 99.8%, prepared using conventional processes.

[0131] Implementation Results Example

[0132] Performance tests were conducted on the soft composite silicon micropowders prepared in Examples 1-8 and Comparative Examples 1 and 2.

[0133] Mohs hardness testing method: The Mohs hardness of the base glass frit materials prepared in the examples and comparative examples was determined according to GB / T9966.5-2020 "Natural Stone Test Methods Part 5: Hardness Test";

[0134] Method for detecting the coefficient of thermal expansion: The coefficient of thermal expansion of the base glass frit prepared in the example was determined according to GB / T 16920-2015 "Determination of the average linear thermal expansion coefficient of glass".

[0135] Table 1 Performance tests of the flexible composite silicon micropowders prepared in Examples 1-8 and Comparative Examples 1 and 2

[0136]

[0137] The soft composite silicon micropowders obtained in Examples 1-8 of this invention have a stable Mohs hardness of 5, significantly lower than Comparative Examples 1 and 2, indicating superior processing performance. The coefficient of thermal expansion is controlled at 3.92 × 10⁻⁶. -6 / K~5.55×10 -6 The / K range is much lower than that of Comparative Example 1 (8.30×10). -6 / K), significantly improving dimensional stability; while avoiding the problems of excessively low expansion and poor compatibility with substrates of high-purity quartz powder. The particle size D50 of each embodiment is controlled at 3.0μm, with uniform distribution, meeting the fine requirements of electronic packaging and copper-clad laminate fillers.

[0138] In summary, this invention achieves both low hardness and low coefficient of thermal expansion through multi-component synergistic regulation, resulting in significantly superior overall performance compared to existing commercially available products, demonstrating outstanding technical advantages.

[0139] The parts of this invention not described in detail are techniques known to those skilled in the art.

[0140] The basic principles of the present invention have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in the present invention are merely examples and not limitations, and should not be considered as essential features of each embodiment of the present invention. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the present invention to the necessity of employing the aforementioned specific details.

[0141] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A soft composite silica powder with low hardness and controllable thermal expansion, characterized in that, The flexible composite silica powder comprises the following raw materials in parts by weight: Silica: 50.0~90.0 parts; Limestone: 1.0~20.0 parts; Feldspar: 1.0~15.0 parts; Boronite: 0.0~10.0 parts; Magnesite: 0.0~10.0 parts; Fluorite: 0.0~5.0 parts; Apatite: 0.0~5.0 parts.

2. The flexible composite silica powder according to claim 1, characterized in that, The flexible composite silica powder comprises the following raw materials in parts by weight: Silica: 65.0~85.0 parts; Limestone: 5.0~18.0 parts; Feldspar: 3.0~12.0 parts; Boronite: 0.5~8.0 parts; Magnesite: 1.0~8.0 parts; Fluorite: 0.1~4.0 parts; Apatite: 0.1~3.0 parts.

3. The flexible composite silica powder according to claim 1 or 2, characterized in that, The soft composite silica powder meets the following requirements: Mohs hardness 4~6, coefficient of thermal expansion 2.0×10⁻⁶. -6 / K~8.0×10 -6 / K, particle size distribution D50 is 0.5 μm ~ 6.0 μm.

4. The flexible composite silica powder according to claim 3, characterized in that, The soft composite silica powder meets the following requirements: Mohs hardness 4.5~5.5, coefficient of thermal expansion 3.0×10⁻⁶. -6 / K~6.0×10 -6 / K, particle size distribution D50 is 1.0 μm ~ 5.0 μm.

5. A method for preparing flexible composite silica micropowder according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Mix the raw materials to obtain the batch; (2) Melt the batch material from step (1) to obtain glass melt; then roll or quench it in water to obtain basic glass frit material; (3) The basic glass frit material from step (2) is dried, ball-milled, air-jet pulverized and classified in sequence to obtain soft composite silicon micro powder.

6. The preparation method according to claim 5, characterized in that, The mixing time in step (1) is 3.0~60.0 min; And / or, the melting process described in step (2) includes: melting at 1400~1650℃ for 0.5~8.0 h; And / or, the ball milling time in step (3) is 0.5~6.0 h; And / or, the time for airflow pulverization in step (3) is 0.5~4.0 h.

7. The preparation method according to claim 6, characterized in that, The mixing time in step (1) is 5.0~60.0 min; And / or, the melting process in step (2) includes: 1450~1600℃, holding time of 1.0~6.0 h; And / or, the ball milling time in step (3) is 1.0~5.0 h; And / or, the time for airflow pulverization in step (3) is 1.0~3.0 h.

8. An inorganic packing material, characterized in that, The inorganic filler includes the soft composite silicon micro powder according to any one of claims 1 to 4 or the soft composite silicon micro powder prepared by the preparation method according to any one of claims 5 to 7.

9. The application of the inorganic filler as described in claim 8 in electronic packaging materials, rubber and plastic functional materials, and copper clad laminate fillers.

10. An electronic packaging material, characterized in that, The electronic packaging material includes the flexible composite silicon micropowder according to any one of claims 1 to 4 or the flexible composite silicon micropowder prepared by the preparation method according to any one of claims 5 to 7.

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