Lithium-lanthanum-silicon microcrystalline glass and preparation method thereof

Abstract

The invention discloses a lithium lanthanum silicon series microcrystalline glass and a preparation method thereof, and the lithium lanthanum silicon series microcrystalline glass comprises the following components in percentage by mass: 12%-22% of Li2O, 19%-29% of La2O3, 42%-64% of SiO2, 0.5%-1.2% of ZrO2, 0.2%-1.0% of P2O5, 0%-4.0% of MgF2 and 0%-2.0% of Al2O3. Wherein SiO2 is a glass network forming body, provides a main skeleton structure and ensures the mechanical strength; la2O3 is a network intermediate for strengthening a glass network, so that a stable crystal phase is favorably formed, and the dielectric property and the chemical stability of the glass are improved. Li2O is a network modifier and is used for reducing the melting temperature of the glass and improving the chemical stability of the glass. Besides, a small amount of ZrO2, P2O5 and MgF2 are added as nucleating agents, crystallization of the glass can be promoted, so that the dielectric loss of the material is reduced, and a proper amount of Al2O3 is added, so that the viscosity of the glass can be improved, and glass melting is facilitated.

Description

Technical Field

[0001] This invention relates to the field of special glass materials technology, specifically a lithium lanthanum silicon-based microcrystalline glass and its preparation method. Background Technology

[0002] Glass-ceramics, combining the ease of processing of glass with the excellent mechanical and thermal properties of ceramics, have become a key material for low-temperature co-fired ceramic (LTCC) substrates. An ideal LTCC substrate material must possess low dielectric constant / loss, low sintering temperature (<900℃), and high mechanical strength.

[0003] The widely used traditional glass-ceramic systems, such as CaO-B2O3-SiO2, have excessive residual glass phase after sintering, resulting in generally low flexural strength (typically <150MPa). To improve strength, the industry usually adopts a strategy of combining glass-ceramic with ceramic phases. However, this requires the glass-ceramic itself to have a low softening point to ensure sufficient flow and wetting of ceramic particles during sintering.

[0004] Lanthanum oxide (La2O3) has been introduced into glass-ceramic systems to improve their properties. However, existing lanthanum-containing technologies have significant limitations: for example, while some systems can improve mechanical or optical properties, they suffer from high softening points and difficulties in controlling crystallization (e.g., CN104556701A); other systems consume enormous amounts of energy due to excessively high preparation temperatures (1500℃) and are not suitable for temperature-sensitive LTCC processes (e.g., CN106630636A).

[0005] In summary, the existing technology lacks a microcrystalline glass material that can simultaneously satisfy the requirements of low softening point, strong crystallization characteristics, excellent dielectric properties, and low-temperature preparation, which seriously restricts the development of high-performance LTCC technology. Summary of the Invention

[0006] In view of the above, the present invention provides a lithium lanthanum silicon-based microcrystalline glass and its preparation method to solve the problems mentioned in the background art. The microcrystalline glass has the characteristics of low dielectric constant and low loss, is suitable for LTCC substrate materials, and can meet the stringent requirements of electronic packaging for material performance.

[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, this invention discloses a lithium-lanthanum-silicon-based microcrystalline glass, which, by mass percentage, comprises the following components: Li₂O 12%-22%, La₂O₃ 19%-29%, SiO₂ 42%-64%, ZrO₂ 0.5%-1.2%, P₂O₅ 0.2%-1.0%, MgF₂ 0%-4.0%, and Al₂O₃ 0%-2.0%. SiO₂ serves as the glass network forging body, providing the main skeletal structure and ensuring mechanical strength; La₂O₃ acts as a network intermediate, strengthening the glass network and contributing to the formation of a stable crystalline phase, thereby improving the dielectric properties and chemical stability of the glass; Li₂O acts as a network modifier, used to lower the glass melting temperature and improve the glass's chemical stability. Furthermore, the addition of small amounts of ZrO₂, P₂O₅, and MgF₂ as nucleating agents promotes glass crystallization, thereby reducing the dielectric loss of the material; and the addition of an appropriate amount of Al₂O₃ increases the glass viscosity, facilitating glass melting.

[0008] A further option: the softening point of the microcrystalline glass is 640℃-705℃.

[0009] A further embodiment: the microcrystalline glass has a dielectric constant of less than 7.0 and a dielectric loss of no more than 0.003 at 10 GHz.

[0010] A further option is to sinter the microcrystalline glass at a temperature of less than 850°C.

[0011] A further embodiment: the main crystalline phases of the microcrystalline glass include Li2SiO3 and LaSiO3.

[0012] Secondly, the present invention discloses a method for preparing the above-mentioned lithium lanthanum silicon-based microcrystalline glass, comprising the following steps: S1. Thoroughly mix all raw materials to form a mixture; S2. Melt the mixture at 1250℃-1350℃ for 0.5h-1h to obtain glass slag; S3. Grind the glass slag to control the particle size of the glass powder after ball milling to be between 2.5μm and 4.0μm, and obtain lithium lanthanum silicon-based microcrystalline glass powder.

[0013] A further option: In step S3, the grinding is ball milling, the ball milling speed is 350 r / min-400 r / min, and the ball milling time is 4h-6h.

[0014] Thirdly, the present invention discloses a low-temperature co-fired ceramic packaging substrate, which is prepared using lithium lanthanum silicon-based microcrystalline glass as described above.

[0015] Compared with the prior art, the beneficial effects of the present invention are: Low softening point: The lithium lanthanum silicon-based glass-ceramic in this invention has a low softening point (the lowest softening point Tg is around 640℃), which is much lower than that of traditional CaO-B2O3-SiO2 system glass-ceramic (usually above 700℃).

[0016] Adjustable performance: By adjusting the proportions of La2O3, Li2O, and SiO2 in the glass-ceramic, the softening point of the lithium lanthanum silicon-based glass-ceramic can be adjusted within the range of 640℃ to 705℃. A lower softening point allows the glass-ceramic to be sintered in the range of <850℃.

[0017] Enhancing crystallization ability: Adding appropriate amounts of ZrO2, MgF2, and P2O5 as glass nucleating agents induces the formation of low-loss Li2SiO3 and LaSiO3 phases during glass sintering, thereby increasing the amount of crystallization in the glass. The dielectric constant of the microcrystalline glass sintered at temperatures below 850℃ is <7.0, and the dielectric loss is as low as approximately 0.0025 (10 GHz). Simultaneously, ZrO2 also improves the insulating resistivity of the glass.

[0018] Improving processing performance: Adding Li2O can improve the chemical stability and corrosion resistance of glass; adding an appropriate amount of Al2O3 can increase the viscosity of glass, which helps the glass to be melted in the range of 1250℃-1350℃. Detailed Implementation

[0019] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0021] Any range described in this invention includes the endpoint, any value between the endpoints, and any subrange consisting of the endpoint or any value between the endpoints.

[0022] Example 1 This embodiment provides a lithium lanthanum silicon-based microcrystalline glass, which, by mass percentage, comprises 25% La2O3, 21% Li2O, 50.8% SiO2, 1.0% ZrO2, 0.8% P2O5, 0.5% MgF2, and 0.9% Al2O3.

[0023] The preparation method of lithium lanthanum silicon-based glass-ceramics includes the following steps: Powder mixing: The lithium source in the raw materials is Li2CO 3， The phosphorus source is NH4H2PO4, and the other raw materials are their corresponding oxyfluorides. After weighing each raw material according to the proportion in Table 1, they are put into a ball mill jar and mixed thoroughly for 2 hours to form a uniformly mixed material.

[0024] Table 1 Raw material ratios for Examples 1-3

[0025] Glass melting: The mixture is placed in a platinum crucible and melted at 1250°C for 1 hour to obtain glass slag.

[0026] Glass ball milling: Glass slag is placed in a ball mill jar, water is used as the medium, and zirconia balls are used as the milling balls. The mass ratio of balls, material and water is 2:1:2. The ball milling is carried out at a speed of 350 r / min for 6 hours. The particle size of the glass powder is controlled at 2.5 μm. After drying at 100℃, lithium lanthanum silicon-based microcrystalline glass powder is obtained.

[0027] The softening point of the prepared glass-ceramic powder was 640℃, and the initial crystallization temperature was 681℃. The glass-ceramic powder was pressed into sheets and sintered at 800℃. The resulting ceramic had a dielectric constant (10 GHz) of 6.2, a dielectric loss (10 GHz) of 0.0020, and a coefficient of thermal expansion of 6.1 × 10⁻⁶. -6 K -1 .

[0028] Example 2 This embodiment provides a lithium lanthanum silicon-based microcrystalline glass, which, by mass percentage, comprises 22% La2O3, 13% Li2O, 60.2% SiO2, 0.8% ZrO2, 0.5% P2O5, 2.5% MgF2, and 1.0% Al2O3.

[0029] The preparation method is the same as in Example 1.

[0030] The obtained glass-ceramic had a softening point of 658℃ and an initial crystallization temperature of 713℃. The glass-ceramic powder was pressed into sheets and sintered at 825℃. The resulting ceramic had a dielectric constant (10 GHz) of 6.5, a dielectric loss (10 GHz) of 0.0025, and a coefficient of thermal expansion of 7.8 × 10⁻⁶. -6 K -1 .

[0031] Example 3 This embodiment provides a lithium lanthanum silicon-based microcrystalline glass, which, by mass percentage, consists of 18% La2O3, 15% Li2O, 63.3% SiO2, 0.5% ZrO2, 0.2% P2O5, 2% MgF2, and 1% Al2O3.

[0032] The preparation method is the same as in Example 1.

[0033] The softening point of the prepared glass-ceramic powder was 679℃, and the initial crystallization temperature was 731℃. The glass-ceramic powder was pressed into sheets and sintered at 850℃. The resulting ceramic had a dielectric constant (10 GHz) of 6.0, a dielectric loss (10 GHz) of 0.0030, and a coefficient of thermal expansion of 7.2 × 10⁻⁶. -6 K -1 .

[0034] Comparative Example 1 This comparative example provides a lithium lanthanum silicon-based microcrystalline glass, which, by mass percentage, comprises 23% La2O3, 8% Li2O, 65% SiO2, 0.5% ZrO2, 0.2% P2O5, 2% MgF2, and 1.3% Al2O3.

[0035] The preparation method of lithium lanthanum silicon-based glass-ceramics includes the following steps: Powder mixing: The lithium source in the raw materials is Li2CO 3， The phosphorus source used is NH4H2PO4, and the other raw materials are their corresponding oxyfluorides. After weighing each raw material according to the proportions in Table 2, they are put into a ball mill jar and mixed thoroughly for 2 hours to form a uniformly mixed material.

[0036] Table 2 Raw material ratios for Comparative Examples 1-3

[0037] Glass melting: The mixture is placed in a platinum crucible and melted at 1250°C for 1 hour to obtain glass slag.

[0038] Glass ball milling: Glass slag is placed in a ball mill jar, water is used as the medium, and zirconia balls are used as the milling balls. The mass ratio of balls, material and water is 2:1:2. The ball milling is carried out at a speed of 350 r / min for 6 hours. The particle size of the glass powder is controlled at 2.5 μm. After drying at 100℃, lithium lanthanum silicon-based microcrystalline glass powder is obtained.

[0039] The glass softening point of the prepared microcrystalline glass powder increased to 780℃, the initial crystallization temperature was 858℃, and phase separation occurred during the glass melting process. It did not sinter into porcelain in the temperature range of less than or equal to 850℃, which confirms that the special ratio of La2O3-Li2O-SiO2 plays a key role in reducing the softening point and preventing phase separation.

[0040] Comparative Example 2 This comparative example provides a lithium lanthanum silicon-based microcrystalline glass, which, by mass percentage, has the following composition: La2O3 25%, Li2O 21%, SiO2 50.8%, and ZrO2 1.0%.

[0041] The preparation method of lithium lanthanum silicon-based glass-ceramics includes the following steps: Powder mixing: The lithium source in the raw materials is Li2CO 3， The phosphorus source used is NH4H2PO4, and the other raw materials are their corresponding oxyfluorides. After weighing each raw material according to the proportions in Table 2, they are put into a ball mill jar and mixed thoroughly for 2 hours to form a uniformly mixed material.

[0042] Glass melting: The mixture is placed in a platinum crucible and melted at 1250°C for 1 hour to obtain glass slag.

[0043] Glass ball milling: Glass slag is placed in a ball mill jar, water is used as the medium, and zirconia balls are used as the milling balls. The mass ratio of balls, material and water is 2:1:2. The ball milling is carried out at a speed of 350 r / min for 6 hours. The particle size of the glass powder is controlled at 2.5 μm. After drying at 100℃, lithium lanthanum silicon-based microcrystalline glass powder is obtained.

[0044] The softening point of the microcrystalline glass powder was measured to be 646℃, and the coefficient of thermal expansion was 6.3×10⁻⁶. -6 K -1 The resulting ceramic had a dielectric constant (10 GHz) of 5.5 and a dielectric loss (10 GHz) of 0.006. The results showed a significant reduction in glass crystallization ability, with an initial crystallization temperature of 733℃, a wider crystallization temperature range, and a decrease in the amount of crystals, confirming the important role of ZrO2, P2O5, and MgF2 as nucleating agents in promoting crystallization.

[0045] Comparative Example 3 This comparative example provides a lithium lanthanum silicon-based microcrystalline glass, which, by mass percentage, comprises 20% La2O3, 28% Li2O, 48.3% SiO2, 0.5% ZrO2, 0.2% P2O5, 2.0% MgF2, and 1.0% Al2O3.

[0046] The preparation method includes the following steps: Powder mixing: The lithium source in the raw materials is Li2CO 3， The phosphorus source used is NH4H2PO4, and the other raw materials are their corresponding oxyfluorides. After weighing each raw material according to the proportions in Table 2, they are put into a ball mill jar and mixed thoroughly for 2 hours to form a uniformly mixed material.

[0047] Glass melting: The mixture is placed in a platinum crucible and melted at 1250°C for 1 hour to obtain glass slag.

[0048] Glass ball milling: Glass slag is placed in a ball mill jar, water is used as the medium, and zirconia balls are used as the milling balls. The mass ratio of balls, material and water is 2:1:2. The ball milling is carried out at a speed of 350 r / min for 6 hours. The particle size of the glass powder is controlled at 2.5 μm. After drying at 100℃, lithium lanthanum silicon-based microcrystalline glass powder is obtained.

[0049] The resulting microcrystalline glass powder has a low SiO2 content in the network-forming body and a high Li2O content in the network-modifying body. + Breaking the strong Si-O-Si bonds weakens the glass network structure, leading to a sharp decrease in glass viscosity and a lower softening point (Tg approximately 609℃). When the network structure is broken, the interatomic bonds weaken, making the atoms more prone to vibration and expansion upon heating, resulting in an increased coefficient of thermal expansion (9.1 × 10⁻⁶). -6 K -1 Furthermore, the crystallization ability decreases, resulting in higher dielectric loss (0.008 at 10GHz).

[0050] Although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

[0051] Therefore, the above description is only a preferred embodiment of this application and is not intended to limit the scope of this application; that is, all equivalent modifications made in accordance with the scope of the claims of this application shall be within the protection scope of the claims of this application.

Claims

1. A lithium-lanthanum silicon-based microcrystalline glass, characterized in that, It consists of the following components, expressed as a percentage by mass: Li2O 12%-22%, La2O3 19%-29%, SiO2 42%-64%, ZrO2 0.5%-1.2%, P2O5 0.2%-1.0%, MgF 20%-4.0%, Al2O 30%-2.0%.

2. The lithium-lanthanum silicon-based microcrystalline glass according to claim 1, characterized in that, The softening point of the microcrystalline glass is 640℃-705℃.

3. The lithium-lanthanum silicon-based microcrystalline glass according to claim 1, characterized in that, The microcrystalline glass has a dielectric constant of less than 7.0 and a dielectric loss of no more than 0.003 at 10 GHz.

4. The lithium-lanthanum silicon-based microcrystalline glass according to claim 1, characterized in that, The sintering temperature of the microcrystalline glass is less than 850°C.

5. The lithium-lanthanum silicon-based microcrystalline glass according to claim 1, characterized in that, The main crystalline phases of the microcrystalline glass include Li2SiO3 and LaSiO3.

6. A method for preparing lithium lanthanum silicon-based microcrystalline glass as described in any one of claims 1-5, characterized in that, Includes the following steps: S1. Thoroughly mix all raw materials to form a mixture; S2. Melt the mixture at 1250℃-1350℃ for 0.5h-1h to obtain glass slag; S3. Grind the glass slag to control the particle size of the glass powder after ball milling to be between 2.5μm and 4.0μm, and obtain lithium lanthanum silicon-based microcrystalline glass powder.

7. The preparation method according to claim 6, characterized in that, In step S3, the grinding is ball milling, the ball milling speed is 350 r / min-400 r / min, and the ball milling time is 4h-6h.

8. A low-temperature co-fired ceramic packaging substrate, characterized in that, It is prepared using the lithium lanthanum silicon-based microcrystalline glass as described in any one of claims 1-5.

Images