A barium copper silicon-based glass frit for low temperature co-fired ceramic and a preparation method thereof

Abstract

The application belongs to the technical field of electronic materials and ceramic engineering, and relates to a barium copper silicon glass frit for low-temperature co-fired ceramic and a preparation method thereof. The main components of the glass frit are based on a BaO-CuO-SiO2 system, and the glass frit comprises BaO 20-30 wt%, CuO 12-17 wt%, and SiO2 43-54 wt%. On this basis, one or more of Li2O, B2O3, Al2O3, P2O5, SrO and CaO can be selected as a modifier. The glass frit can be sintered at a low temperature of 820-1060 DEG C, has stable dielectric constant (4.4-5.8) and quality factor after sintering, and has a breakdown field strength of 60-200 kV / cm. The glass frit has low sintering temperature, stable dielectric performance and high electrical insulation reliability, and is particularly suitable for the fields of low-temperature co-fired ceramic technology, electronic packaging and functional ceramic coating, which need to be co-fired with high-conductivity metal (such as silver).

Description

Technical Field

[0001] This invention belongs to the field of electronic materials and ceramic engineering technology, specifically relating to a barium copper silicon-based glass glaze for low-temperature co-fired ceramics and its preparation method. Background Technology

[0002] With the development of electronic components towards higher integration, higher frequency, and lower cost, low-temperature co-fired ceramic (LTCC) technology has become one of the mainstream technologies for realizing passive device integration. LTCC technology requires co-firing with a ceramic substrate and conductive paste at temperatures below the melting point of the electrode metal (such as silver) (typically <900℃). Therefore, developing glass glazes with low sintering temperatures, good densification behavior, stable dielectric properties, and compatibility with metal electrodes is crucial. Glass glazes in LTCC are typically applied in powder form, coated onto the surface of the ceramic substrate through screen printing or tape casting, and then sintered to form a dense protective or insulating layer. This requires the glass glaze to have a low softening point, good wettability, and reliable dielectric properties after sintering.

[0003] However, existing research mainly focuses on BaCuSi4O 10 For crystalline ceramics, systematic research on the dielectric behavior, dependence on sintering temperature, and breakdown strength of their derived amorphous glass glazes under low-temperature sintering is still insufficient. Furthermore, existing technologies for sintering glass glazes suffer from a series of problems, including excessively high sintering temperatures, poor compatibility with silver electrodes during co-firing, and unstable dielectric properties. Summary of the Invention

[0004] This invention provides the following technical solution: a barium-copper-silicon glass glaze for low-temperature co-fired ceramics, the glass glaze being prepared from the following raw materials: BaO 20-30 parts by weight, CuO 12-17 parts by weight, SiO2 43-54 parts by weight; the glass glaze also includes modifiers and unavoidable impurities; after sintering at 800-1080℃, the glass glaze has a dielectric constant of 4.4-5.8, a quality factor greater than 1000 GHz, and a breakdown voltage of 60-200 kV / cm.

[0005] Preferably, the modifier includes one or more of Li2O, B2O3, Al2O3, P2O5, SrO, and CaO.

[0006] More preferably, the content of the modifier does not exceed 22 wt% of the total mass of the glass glaze.

[0007] More preferably, when the glass glaze is co-fired with the silver electrode material at ≤ 900 ℃, no obvious interfacial reaction occurs.

[0008] This invention also discloses a method for preparing a barium-copper-silicon glass glaze for low-temperature co-fired ceramics. This method, used to prepare the aforementioned barium-copper-silicon glass glaze, includes the following steps: Step 1, Ingredients: Weigh out the raw materials containing BaO, CuO, and SiO2 according to the specified proportions.

[0009] Step 2, Mixing: The weighed raw materials are ball-milled and then dried.

[0010] Step 3, Melting: The mixed and dried powder is melted at 1400-1600 ℃ to obtain molten glass.

[0011] Step 4, Quenching and Crushing: The molten glass is quenched with water to obtain glass slag, which is then crushed and ground to obtain glass glaze powder.

[0012] Preferably, in step 1, a modifier raw material containing Li2O, B2O3, Al2O3, P2O5, SrO, and CaO is also weighed.

[0013] Preferably, in step 2, the milling media includes ethanol and zirconium oxide balls.

[0014] Preferably, in step 3, the heating rate is 5-10 °C / min, and the temperature is maintained at 1400-1600 °C for 0.5-1 h.

[0015] Preferably, step 4 is followed by: Step 5: Granulate the glass glaze powder, press it into shape, remove the binder at 540-560℃ for no less than 4 hours, and then sinter at 800-1080℃ for no less than 2 hours.

[0016] The present invention also discloses the application of a barium copper silicon-based glass glaze in low-temperature co-fired ceramic substrates, electronic packaging, or functional ceramic coatings.

[0017] The beneficial effects of this invention are: 1. The glass glaze of the present invention has a stable dielectric constant (4.4-5.8) and an acceptable quality factor (Q×f>1000 GHz); the glass breakdown voltage of the present invention is 60-200 kV / cm, showing excellent electrical insulation reliability, which helps to improve the service life and operational stability of LTCC devices.

[0018] 2. This invention achieves densification sintering in a low-temperature range, which is much lower than the sintering temperature of traditional ceramic materials, enabling them to be co-fired with low-melting-point metal electrodes such as Ag and Cu in the LTCC process.

[0019] 3. The glass glaze of this invention does not contain harmful elements such as lead and cadmium, making it environmentally friendly; the raw materials are widely available, the preparation process is simple, and it is easy to industrialize.

[0020] 4. This invention, based on the BaO-CuO-SiO2 system, limits the components within a specific range to obtain a base material that possesses both low melting point and good glass-forming ability. Furthermore, by introducing fluxes such as Li2O and B2O3, the viscosity and sintering temperature of the glass can be further reduced; the introduction of Al2O3 and P2O5 can adjust the glass network structure, improving its chemical stability and electrical insulation properties; and the introduction of SrO and CaO can adjust the coefficient of thermal expansion and dielectric properties of the glass. Through the synergistic effect of multiple modifiers, dense sintering of the glass glaze at low temperatures and stable dielectric properties are achieved. Attached Figure Description

[0021] Figure 1 This invention provides the design basis and preparation process diagram for a barium copper silicon-based glass glaze for low-temperature co-fired ceramics, wherein (a) is a ternary phase diagram of BaO-CuO-SiO2, and (b) is a schematic diagram of the glass glaze preparation process. Figure 2 The graph shows the dielectric properties of the glass glaze and BCS ceramic in different embodiments of the present invention as a function of sintering temperature, where (a) is the dielectric constant and (b) is the quality factor. Detailed Implementation

[0022] The relevant technologies of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0023] like Figures 1-2 As shown, the barium copper silicon-based glass glaze for low-temperature co-fired ceramics of this embodiment comprises the following components by mass percentage, based on the total amount of glass glaze: BaO 20~30 wt%, CuO 12~17 wt%, SiO 243~54 wt%.

[0024] The glass glaze also includes one or more of Li2O, B2O3, Al2O3, P2O5, SrO, and CaO as modifiers, and their total content does not exceed 22 wt% of the total mass of the glass glaze.

[0025] Following the above proportions, the raw materials SiO2, BaCO3, CuO, Li2CO3, Al2O3, B2O3, (NH4)2HPO4, SrCO3, and CaCO3 are mixed and ball-milled using alcohol and zirconium balls as the medium, followed by drying in an oven. The types of glass raw materials introduced can be varied while adhering to the above feeding ratio principles.

[0026] The above-mentioned mixed and dried powder is placed in a box furnace or melting furnace and melted into glass liquid at 1400-1600 ℃. Then it is poured into pure water for quenching. It can be added to a mold to prepare columnar or plate-shaped glass, or further crushed into glass powder and dried for later use.

[0027] The glass melting process involves a heating rate of 5–10 °C / min, followed by holding at 1400–1600 °C for 0.5–1 h. The glass enamel powder is mixed with a polyvinyl alcohol binder and granulated, then pressed into shape under 20 MPa pressure. The green body is then debonded at 550 °C for 4 hours, and finally sintered at 800–1080 °C for 2 hours to obtain glass enamel samples for performance testing.

[0028] Using a network vector analyzer, the glass glaze of this embodiment exhibits a stable dielectric constant (4.4–5.8) and an acceptable quality factor (Q×f > 1000 GHz) over a wide sintering temperature range.

[0029] The electrical properties of the glass, such as the breakdown voltage, were measured using a high-voltage source fixture; specifically, the glass breakdown voltage was 60–200 kV / cm.

[0030] Example Example 1 Glass powder was prepared according to the following proportions: SiO2 53.94 wt%, CuO 16.85 wt%, BaO 29.21 wt%. The weighed raw materials were ball-milled using alcohol and zirconium balls as the medium for 4 hours, and then dried in an oven at 80 ℃.

[0031] The powder was placed in a furnace and heated to 1600 ℃ at a heating rate of 8 ℃ / min. It was held at that temperature for 1 hour, then quenched in pure water and further crushed into glass powder. The powder was then dried and stored for later use.

[0032] Example 2 Glass powder was prepared according to the following proportions: SiO2 48 wt%, CuO 15 wt%, BaO 26 wt%, Li2O 4 wt%, Al2O3 4 wt%, P2O5 4 wt%. The weighed raw materials were ball-milled using alcohol and zirconium balls as the medium for 4 hours, and then dried in an oven set at 80 ℃.

[0033] The powder was placed in a furnace and heated to 1400 ℃ at a heating rate of 8 ℃ / min. It was held at that temperature for 1 hour, then quenched in pure water and further crushed into glass powder. The powder was then dried and stored for later use.

[0034] Example 3 Glass powder was prepared according to the following proportions: SiO2 48 wt%, CuO 12.7 wt%, BaO 20 wt%, Li2O 4 wt%, Al2O3 1.8 wt%, B2O3 11.7 wt%, CaO 1.8 wt%. The weighed raw materials were ball-milled using alcohol and zirconium balls as the medium for 4 hours, and then dried in an oven at 80 ℃.

[0035] The powder was placed in a furnace and heated to 1400 ℃ at a heating rate of 8 ℃ / min. It was held at that temperature for 1 hour, then quenched in pure water and further crushed into glass powder. The powder was then dried and stored for later use.

[0036] Example 4 Glass powder was prepared according to the following proportions: SiO2 43.79 wt%, CuO 13.6 wt%, BaO 21.28 wt%, Li2O 1.92 wt%, Al2O3 1.09 wt%, B2O3 15 wt%, SrO 3.32 wt%. The weighed raw materials were ball-milled using alcohol and zirconium balls as the medium for 4 hours, and then dried in an oven at 80 ℃.

[0037] Examples 1-4 were further heat-treated at 780–1080 °C for 2 hours, and their microwave dielectric properties were tested. (See attached figures.) Figure 2 The glass glazes of Examples 2-4 (glass-2, 3, 4) exhibited a slight temperature dependence in their dielectric constants within the low-temperature sintering range of 780–880 °C, with values ​​remaining stable between 4.4 and 5.8, demonstrating good dielectric stability. Among them, the dielectric constants of Examples 2 and 3 were the most stable, ranging from approximately 4.4 to 4.6.

[0038] The Q×f values ​​of all the glass glazes in the examples were significantly lower than those of the comparative BCS ceramic, a typical characteristic of glass materials. However, the Q×f values ​​of the examples were relatively stable within the low-temperature sintering range of 780–880 °C. Examples 2 and 3 exhibited moderate and small-fluctuation Q×f values. Example 1 showed a Q×f peak near 1060 °C, which subsequently decreased due to overfiring. The Q×f value of the comparative BCS ceramic increased rapidly with increasing temperature, exceeding 50,000 GHz at 1080 °C.

[0039] Based on the above dielectric behavior, the optimal sintering temperature for each sample was determined and their overall performance was summarized in Table 1.

[0040]

[0041] Compared to the comparative BCS ceramic (1080℃) in Table 1, the glass glazes of Examples 2-4 achieved low-temperature sintering at 820–860℃, and the sintering temperature of Example 1 was also reduced to 1060℃. This indicates that by vitrification design and composition control, the sintering temperature of the material was lowered, giving it the potential to be co-fired with Ag electrodes.

[0042] The glass glaze of Example 3, after sintering at 820°C, achieved a breakdown field strength of 200 kV / cm, higher than the 60.2 kV / cm of the comparative BCS ceramic. This is attributed to the dense microstructure formed after glass melting and sintering, which significantly reduces porosity and thus greatly improves the insulation reliability of the material. The breakdown strengths of other examples are also generally higher than or equivalent to those of the ceramic comparative examples.

[0043] The barium copper silicon-based glass glaze provided by this invention, especially those modified with Li2O, B2O3, Al2O3, etc. in Examples 2 and 3, can achieve stable and good dielectric properties and excellent insulation reliability at sintering temperatures significantly lower than those of traditional ceramics. It is very suitable for application in low-temperature co-fired ceramic technology. This invention achieves synergistic optimization of low sintering temperature, low dielectric constant and high breakdown strength.

[0044] In summary, the barium-copper-silicon glass glaze provided by this invention achieves densification sintering in a low-temperature range of 820–1060℃ by precisely controlling the basic components of the BaO-CuO-SiO2 system and introducing modifiers such as Li2O and B2O3. Its dielectric constant is stable at 4.4–5.8, quality factor Q×f > 1000 GHz, and breakdown voltage reaches 60–200 kV / cm. It also possesses low melting point, good dielectric properties, high insulation reliability, and environmental friendliness. The raw materials for this glass glaze are widely available, the preparation process is simple, and it can be co-fired with low-melting-point metal electrodes such as Ag and Cu. This effectively solves the problems of excessively high sintering temperature, unstable dielectric properties, and poor compatibility with electrodes in traditional low-temperature co-fired ceramic glass glazes. It provides key material support for the development of low-temperature co-fired ceramic technology and has significant industrial application value.

[0045] It should be emphasized that the above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A barium-copper-silicon glass glaze for low-temperature co-fired ceramics, characterized in that, The glass glaze is prepared from the following raw materials: BaO 20-30 parts by weight, CuO 12-17 parts by weight, and SiO2 43-54 parts by weight. The glass glaze also includes modifiers and unavoidable impurities; After sintering at 800–1080℃, the glass glaze has a dielectric constant of 4.4–5.8, a quality factor greater than 1000 GHz, and a breakdown voltage of 60–200 kV / cm.

2. The barium-copper-silicon glass glaze for low-temperature co-fired ceramics according to claim 1, characterized in that, The modifier includes one or more of Li2O, B2O3, Al2O3, P2O5, SrO, and CaO.

3. The barium-copper-silicon glass glaze for low-temperature co-fired ceramics according to claim 2, characterized in that, The content of the modifier does not exceed 22 wt% of the total mass of the glass glaze.

4. The barium-copper-silicon glass glaze for low-temperature co-fired ceramics according to claim 3, characterized in that, When the glass glaze is co-fired with the silver electrode material at ≤ 900 ℃, no obvious interfacial reaction occurs.

5. A method for preparing a barium-copper-silicon glass glaze for low-temperature co-fired ceramics, characterized in that, The preparation method is used to prepare the barium copper silicon-based glass glaze according to any one of claims 1 to 4, and the preparation method includes the following steps: Step 1, Ingredients: Weigh out the raw materials containing BaO, CuO, and SiO2 according to the specified proportions; Step 2, Mixing: Ball mill the weighed raw materials and then dry them; Step 3, Melting: The mixed and dried powder is melted at 1400-1600 ℃ to obtain molten glass; Step 4, Quenching and Crushing: The molten glass is quenched with water to obtain glass slag, which is then crushed and ground to obtain glass glaze powder.

6. The method for preparing a barium-copper-silicon glass glaze for low-temperature co-fired ceramics according to claim 5, characterized in that, In step 1, modifier raw materials containing Li2O, B2O3, Al2O3, P2O5, SrO, and CaO are also weighed.

7. The method for preparing a barium-copper-silicon glass glaze for low-temperature co-fired ceramics according to claim 5, characterized in that, In step 2, the milling media include ethanol and zirconium oxide balls.

8. The method for preparing a barium-copper-silicon glass glaze for low-temperature co-fired ceramics according to claim 5, characterized in that, In step 3, the heating rate is 5-10 °C / min, and the temperature is maintained at 1400-1600 °C for 0.5-1 h.

9. A method for preparing a barium-copper-silicon glass glaze for low-temperature co-fired ceramics according to claim 5, characterized in that, Step 4 is followed by: Step 5: Granulate the glass glaze powder, press it into shape, remove the binder at 540-560℃ for no less than 4 hours, and then sinter at 800-1080℃ for no less than 2 hours.

10. The application of a barium copper silicon-based glass glaze as described in any one of claims 1-4 in low-temperature co-fired ceramic substrates, electronic packaging, or functional ceramic coatings.

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