LTCC (Low Temperature Co-Fired Ceramic) material with ultralow dielectric constant and preparation method thereof

Abstract

The invention discloses an ultralow dielectric constant LTCC (Low Temperature Co-Fired Ceramic) material and a preparation method thereof. The ultralow dielectric constant LTCC material is composed of aSiO2-bB2O3-cM2O3-dGO2-eR2O-fR 'O glass + (xSiO2 + yA) filler, M is at least one of Al, Ga, Cr, Bi, Nd, Sm and La, G is at least one of Zr and Ti, R is at least one of Li, Na and K, R' is at least one of Ca, Sr, Mg, Zn, Mn, Ba and Cu, and A is at least one of Al2O3, MgAl2O4, ZnAl2O4, mullite, zirconium oxide and cordierite. The LTCC material provided by the invention not only has excellent dielectric properties, but also has good water resistance, acid and alkali corrosion resistance and thermodynamic stability, is high in reliability, and is beneficial to large-scale production and stable application.

Description

Technical Field

[0001] The present invention belongs to the technical field of low temperature co-fired ceramics (LTCC), and particularly relates to an ultra-low dielectric constant LTCC material and a preparation method thereof. Background Art

[0002] The low temperature co-fired ceramics (LTCC) technology is one of the core technologies for passive integration and packaging interconnection. It is to make a green ceramic tape by casting the green ceramic powder of low temperature sintered ceramics, and then use processes such as punching, via filling, and electrode printing on the green ceramic tape to produce the required circuit patterns; and a variety of passive components (such as capacitors, resistors, filters, couplers, etc.) can be buried in a multi-layer ceramic substrate, and then laminated together and sintered below 950 °C to make a three-dimensional high-density circuit; it can also be made into a three-dimensional circuit substrate with built-in passive components, and integrated circuits (ICs) and active devices are surface-mounted on its surface to make a passive / active integrated functional module, which is particularly suitable for components used in high-frequency communication. Due to its excellent electrical, mechanical, thermal and process characteristics, the LTCC technology has become the core technology for the miniaturization, integration and modularization of electronic components, and has been widely used in the fields of aviation, aerospace, military, automotive electronics, wireless communication, etc.

[0003] The LTCC material is the basis of the LTCC technology, and the dielectric constant of the LTCC material directly affects the signal transmission speed in high-frequency circuits. From the relationship between the two, it can be known that the signal transmission delay time is proportional to the square root of the dielectric constant. Therefore, using a substrate material with a low dielectric constant can obtain lower signal delay and higher transmission rate. In the field of LTCC materials, an ultra-low dielectric constant usually means a relative dielectric constant ≤ 4.0. Most of the ceramic phases in LTCC materials have a dielectric constant > 6.0, and there are very few ceramic phases with a dielectric constant ≤ 4.0. The SiO2 ceramic is the simplest and most common ultra-low dielectric constant ceramic phase among them, with a relative dielectric constant ≤ 3.8 and a high quality factor at the same time. However, the sintering temperature of SiO2 is extremely high, often above 1600 °C, which cannot meet the usage requirements of LTCC materials.

[0004] Patents (CN114206794A, CN113461413A, EP3480179A1) obtain LTCC materials with a sintering temperature ≤ 950 °C and a relative dielectric constant ≤ 4.0 by using borosilicate glass with a high silicon content + SiO2 ceramics. However, the main component SiO2 in borosilicate glass has a framework network structure, while B2O3 has a layered structure. Due to their different structures, it is difficult for them to form a uniform melt, which easily leads to glass delamination and phase separation. B2O3 in the boron-rich phase is extremely hygroscopic and easily forms B(OH)3, while the silicon-rich phase is prone to precipitating high-thermal-expansion quartz crystal phases during the sintering process, resulting in poor thermodynamic stability. The above characteristics deteriorate the water resistance, acid and alkali corrosion resistance, and thermodynamic stability of LTCC materials. The product is prone to corrosion and failure in high-humidity, acid-base plating solution environments, and the precipitation of high-thermal-expansion quartz phases during the sintering process will also cause cracks. The existence of these problems will seriously damage the reliability and stability of the product, greatly limiting the large-scale stable production and application of ultra-low dielectric constant LTCC materials. Therefore, how to obtain ultra-low dielectric constant LTCC materials with good water resistance, acid and alkali corrosion resistance, thermodynamic stability, and excellent dielectric properties has become a technical problem in the LTCC technology field. Summary of the Invention

[0005] The present invention provides an ultra-low dielectric constant LTCC material and a preparation method thereof, aiming to solve the problems in the prior art that the water and acid-base corrosion resistance of borosilicate ultra-low dielectric constant LTCC materials are poor, and the thermodynamic stability of the LTCC material sintered body is poor, such as the easy precipitation of high-thermal-expansion quartz crystal phases during the sintering process and the poor acid and alkali corrosion resistance of the sintered body. The ultra-low dielectric constant LTCC material of the present invention has good water resistance, acid and alkali corrosion resistance, thermodynamic stability, and excellent dielectric properties and reliability at the same time.

[0006] In a first aspect, the present invention provides an ultra-low dielectric constant LTCC material. The ultra-low dielectric constant LTCC material comprises aSiO2-bB2O3-cM2O3-dGO2-eR2O-fR’O glass + (xSiO2+yA) filler, wherein M is at least one of Al, Ga, Cr, Bi, Nd, Sm, La, G is at least one of Zr, Ti, R is at least one of Li, Na, K, R’ is at least one of Ca, Sr, Mg, Zn, Mn, Ba, Cu, A is at least one of Al2O3, MgAl2O4, ZnAl2O4, mullite, zirconia, cordierite, and a, b, c, d, e, f, x, y are mass percentages, 35% ≤ a ≤ 78%, 9% ≤ b ≤ 20%, 0.25% ≤ c ≤ 4%, d ≤ 2%, e ≤ 2%, f ≤ 2%, x ≤ 50%, y ≤ 5%, and a + b + c + d + e + f + x + y = 100%.

[0007] Preferably, 0.25% ≤ d ≤ 2%, 0.1% ≤ e ≤ 2%, 0.1% ≤ f ≤ 2%, 5% ≤ x ≤ 50%, 1% ≤ y ≤ 5%.

[0008] Preferably, a + x ≤ 85%, and preferably, 65% < a + x ≤ 85%.

[0009] Preferably, the SiO2 filler is one or a mixture of several of α - quartz, α - cristobalite, β - tridymite, fused quartz; preferably, the SiO2 filler is fused quartz.

[0010] Preferably, the moisture content of the ultra - low dielectric constant LTCC material does not change significantly after being exposed to air for more than 7 days.

[0011] In a second aspect, the present invention provides a method for preparing the ultra - low dielectric constant LTCC material. Weigh each raw material according to the composition of aSiO2 - bB2O3 - cM2O3 - dGO2 - eR2O - fR’O glass. After melting the raw materials at high temperature, obtain glass powder through water quenching and grinding. Mix the glass powder, SiO2 filler and A filler to obtain the ultra - low dielectric constant LTCC material.

[0012] Preferably, the particle size of the glass powder is 0.5 - 3μm; the particle size of the filler is 0.5 - 4μm.

[0013] In a third aspect, the present invention provides a sintered body of the ultra - low dielectric constant LTCC material. The sintered body of the ultra - low dielectric constant LTCC material is obtained by sintering the ultra - low dielectric constant LTCC material.

[0014] Preferably, the relative dielectric constant of the sintered body of the ultra - low dielectric constant LTCC material (at 25°C, 10 - 18 GHz) is 3.8 - 5.0, preferably 3.8 - 4.0; the tangent of the loss angle is below 0.003, preferably below 0.002; the weight change rate after soaking in water, strong acid and strong base solutions and at 50°C for more than 24 h < 0.1%, and the surface morphology and properties do not change significantly.

[0015] In a fourth aspect, the present invention provides a method for preparing a sintered body of the low dielectric constant LTCC material. Sinter the ultra - low dielectric constant LTCC material to obtain a sintered body of the ultra - low dielectric constant LTCC material; preferably, the sintering temperature is 850 - 950°C; more preferably, the sintering temperature is 850 - 920°C. This sintering temperature can use low - melting - point metals such as Ag and Cu as co - fired conductor materials.

[0016] Beneficial effects

[0017] The present invention improves the glass network structure by reasonably adjusting the silicon and boron contents in borosilicate glass and adding appropriate amounts of effective glass modifiers and intermediates (cM2O3-dGO2-eR2O-fR’O), inhibits glass phase separation to improve the water resistance and acid and alkali corrosion resistance, and inhibits the precipitation of high thermal expansion quartz crystal phase to improve the thermodynamic stability; adjusts the dielectric properties and sintering temperature by compounding glass powder and fillers such as SiO2, and further improves the thermodynamic stability and water resistance and acid and alkali corrosion resistance during the sintering process of the material, finally solves the problems of poor water resistance, acid and alkali corrosion resistance and poor thermodynamic stability of the existing borosilicate ultra-low dielectric constant LTCC materials, and obtains an ultra-low dielectric constant LTCC material with excellent and stable dielectric properties, which is beneficial to be used in the fields of communication electronic components, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is the XRD change of the LTCC materials in the examples and comparative examples before and after being exposed to air for 7 days;

[0019] Figure 2 It is the XRD difference of the LTCC materials in the examples and comparative examples before and after sintering. DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will be further described through the embodiments. It should be understood that the following embodiments are only used to illustrate the present invention, rather than limiting the present invention.

[0021] The composition of the ultra-low dielectric constant LTCC material is aSiO2-bB2O3-cM2O3-dGO2-eR2O-fR’O glass + (xSiO2+yA) filler. Wherein, M is at least one of Al, Ga, Cr, Bi, Nd, Sm, La, G is at least one of Zr, Ti, R is at least one of Li, Na, K, and R’ is at least one of Ca, Sr, Mg, Zn, Mn, Ba, Cu. The A filler is at least one of Al2O3, MgAl2O4, ZnAl2O4, mullite, zirconia, cordierite.

[0022] a, b, c, d, e, f, x, y are mass percentages, 35% ≤ a ≤ 78%, 9% ≤ b ≤ 20%, 0.25% ≤ c ≤ 4%, d ≤ 2%, e ≤ 2%, f ≤ 2%, x ≤ 50%, y ≤ 5%, a + b + c + d + e + f + x + y + z = 1.

[0023] In an alternative embodiment, in the composition of the ultra-low dielectric constant LTCC material, 35% ≤ a ≤ 78%. In this way, the dielectric properties, melting characteristics, and sintering temperature of the glass can be comprehensively balanced. If the mass ratio of SiO2 in the glass is too low, the proportions of other components in the glass such as B2O3, alkali metal oxides, and alkaline earth metal oxides will increase, or the proportion of the filler will increase, which easily causes problems such as poor water resistance or deterioration of dielectric properties, specifically manifested as an increase in dielectric constant and dielectric loss, or too high a sintering temperature. If the mass ratio of SiO2 in the glass is too high, the proportions of other components in the glass such as B2O3, alkali metal oxides, alkaline earth metal oxides, and common glass additives will decrease, or the proportion of the filler will decrease, which easily leads to too high a glass melting temperature and slow flow rate of the glass liquid, resulting in low glass melting efficiency and poor clarification effect, or too high a sintering temperature. For example, the sintering temperature is higher than 950 °C, which causes it impossible to co-fire with low-melting conductor materials such as Au, Ag, and Cu.

[0024] In an alternative embodiment, in the composition of the ultra-low dielectric constant LTCC material, 9% ≤ b ≤ 20%. In this way, the melting characteristics and phase separation of the glass can be comprehensively balanced. If the mass ratio of B2O3 in the glass is too low, it is easy to cause the flow rate of the glass liquid to be slow, which in turn makes it difficult to effectively water-quench the glass and may lead to too high a final sintering temperature of the material. If the mass ratio of B2O3 in the glass is too high, it is easy to cause phase separation of the glass, which in turn leads to poor water, acid, and alkali corrosion resistance of the material and precipitation of quartz crystal phases.

[0025] In an alternative embodiment, in the composition of the ultra-low dielectric constant LTCC material, 0.25% ≤ c ≤ 4%. In this way, the dielectric properties and phase separation of the glass can be comprehensively balanced. If the mass ratio of M2O3 in the glass is too low, it is difficult to play a role in suppressing glass phase separation, which in turn leads to poor water, acid, and alkali corrosion resistance of the material and precipitation of quartz crystal phases; if the mass ratio of M2O3 in the glass is too high, it is easy to cause the dielectric constant of the final material to increase, and it is impossible to achieve a dielectric constant ≤ 4.0.

[0026] In an alternative embodiment, in the composition of the ultra-low dielectric constant LTCC material, d ≤ 2%. In this way, while improving the acid and alkali corrosion resistance of the material, the dielectric properties can be ensured. If the mass ratio of GO2 in the glass is too high, it is easy to cause the dielectric constant of the final material to increase, and it is impossible to achieve a dielectric constant ≤ 4.0. As an example, 0.25% ≤ d ≤ 2%.

[0027] In an alternative embodiment, in the composition of the ultra-low dielectric constant LTCC material, e ≤ 2% and f ≤ 2%. In this way, while ensuring that the glass is more conducive to melting and suppressing glass phase separation, the dielectric properties of the glass can be comprehensively balanced. If the mass ratio of R2O or R’O in the glass is too high, it is easy to cause an increase in both the dielectric constant and loss of the material. As an example, 0.1% ≤ e ≤ 2%; 0.1% ≤ f ≤ 2%.

[0028] In an alternative embodiment, in the composition of the ultra-low dielectric constant LTCC material, x ≤ 50%. In this way, a more suitable dielectric constant and sintering temperature can be obtained. If the mass ratio of the SiO2 filler is too high, the sintering temperature is higher than 920 °C, even higher than 950 °C. As an example, 5% ≤ x ≤ 50%.

[0029] In an alternative embodiment, in the composition of the ultra-low dielectric constant LTCC material, y ≤ 5%. In this way, while ensuring that the material has better acid and alkali corrosion resistance and suppressing the precipitation of quartz crystal phase, the dielectric constant of the material is ensured to be ≤ 4.0. If the mass ratio of the A filler is too high, it is easy to cause the dielectric constant of the final material to become larger, and it is impossible to achieve a dielectric constant ≤ 4.0. As an example, 1% ≤ y ≤ 5%. Further, 1% ≤ y ≤ 2%.

[0030] The SiO2 filler is one or a mixture of several of α-quartz, α-cristobalite, α-tridymite, and fused quartz. Preferably, the SiO2 filler is fused quartz. When SiO2 is α-quartz, α-cristobalite, or α-tridymite, since α-quartz undergoes a phase transformation at ~573 °C, α-cristobalite at 180 - 270 °C, and α-tridymite at 160 °C, the volume change accompanying the phase transformation causes cracks inside, thus greatly reducing the mechanical strength of the product.

[0031] The following is an exemplary description of the preparation method of the above ultra-low dielectric constant LTCC material.

[0032] According to the composition of the glass in the LTCC material, SiO2, B2O3, M2O3, GO2, R2O, and R’O powders are weighed respectively, and after being mixed evenly, glass cullet is obtained by the melt quenching method. The melting temperature is 1500 - 1650 °C, and the melting holding time is 90 - 180 min. The water temperature for water quenching can be maintained at 20 - 30 °C.

[0033] According to the composition of the LTCC material, glass powder and filler powder are weighed respectively, and after being ball-milled and mixed and then dried, an ultra-low dielectric constant LTCC material is obtained. The ball-milling parameters can be changed as needed. For example, the ball-milling speed is 200 - 500 r / min, and the ball-milling time is 30 - 120 min.

[0034] In an alternative embodiment, in the composition of the ultra-low dielectric constant LTCC material, the particle size of the glass powder is 0.5 - 3 μm, and the particle size of the added filler powder is 0.5 - 4 μm, so as to balance the sintering shrinkage rate, sintering temperature and sintering density of the material. When the filler particle size is too small, the sintering shrinkage rate of the product is too large, which is not conducive to matching with the electrode paste; when the filler particle size is too large, the sintering temperature is too high, which is also not conducive to sintering density.

[0035] Sinter the ultra-low dielectric constant LTCC material to obtain a sintered LTCC material body. The sintering process of LTCC is a conventional process in the art. As an example, the sintering temperature is 850 - 950 °C, preferably 850 - 920 °C. This sintering temperature can be applied to low melting point metals such as Au, Ag, Cu as co-fired conductor materials. The time at the sintering temperature can be 0.5 - 2 hours. For example, a binder is added to the LTCC material for granulation, and then dry-pressed and sintered to obtain a sintered LTCC material body. The type and dosage of the binder, as well as the forming process, are all conventional process parameters in the art.

[0036] The LTCC material not only has excellent dielectric properties, with a relative dielectric constant of 3.8 - 5.0 (preferably 3.8 - 4.0) and a loss tangent of less than 0.003 (preferably less than 0.002) at 25 °C and 10 - 18 GHz, but also has good water resistance, acid and alkali corrosion resistance, and thermodynamic stability.

[0037] The following further lists examples to illustrate the present invention in detail. It should also be understood that the following examples are only used to further illustrate the present invention and cannot be construed as limiting the protection scope of the present invention. Those skilled in the art's non-essential improvements and adjustments based on the above content of the present invention all fall within the protection scope of the present invention. The specific process parameters and the like in the following examples are also only an example within a suitable range, that is, those skilled in the art can make selections within a suitable range through the description herein, rather than being limited to the specific values in the following examples.

[0038] Examples and Comparative Examples

[0039] The preparation method of the specimen can specifically include the following steps:

[0040] (1) Preparation of glass powder. Weigh SiO2, B2O3, Al2O3, GO2 (such as ZrO2), R2O (including Li2O, Na2O, K2O), and R’O (including CaO, ZnO, MgO) according to the glass composition, mix the above components through a mixer, then load them into a crucible, heat to 1600 °C for melting, keep warm for 120 min, and then pour into pure water at 20 - 30 °C for quenching. Dry, crush, and ball-mill the obtained glass slag to obtain glass powder with a particle size of 0.5 - 3 μm.

[0041] (2) Preparation of LTCC material samples. According to the composition of the LTCC material, weigh the glass powder, fused quartz, Al2O3 filler, and ZnAl2O4 filler powder respectively, mix them by ball milling and then dry to obtain the ultra-low dielectric constant LTCC material.

[0042] (3) Sampling and sintering of LTCC materials. Add an aqueous PVA binder solution with a mass percentage of 15% to the LTCC material samples prepared in step (2) for granulation. The mass of the binder aqueous solution is 2wt% of the LTCC material samples. Subsequently, cylindrical samples with a diameter of 13 mm and a height of 6 - 8 mm are obtained by dry pressing, and finally sintered at 900 °C for 2 hours to obtain the LTCC material sintered body samples.

[0043] (4) Performance testing

[0044] Glass melting property: When the glass is melted at 1600 °C, it is difficult to melt to form a uniform glass liquid, or the fluidity of the glass liquid is extremely poor and effective water quenching cannot be carried out, then the glass melting is judged as NG.

[0045] Water resistance: Expose the LTCC powder material obtained in step (2) to the air for 7 days, and test the changes in moisture content and XRD before and after storage. Immerse the LTCC material sintered body obtained in step (3) in water at 50 °C for 24 hours, and test the changes in sample weight, surface morphology, and dielectric properties before and after immersion. If the above properties change significantly, for example, the moisture content of the LTCC powder material increases significantly, a new B(OH)3 crystal phase (PDF#30 - 0199) appears in the XRD, or the weight, surface morphology, and dielectric properties of the sintered body deteriorate after being immersed in water at 50 °C for 24 hours, then the water resistance is judged as NG. If none of the above properties change significantly, then the water resistance is judged as OK.

[0046] Thermodynamic stability: Perform XRD analysis on the LTCC material samples and LTCC material sintered body samples obtained in step (2) and step (3) to obtain the phase changes before and after sintering, so as to judge whether there is a high - thermal - expansion quartz crystal phase precipitated after sintering. If no high - expansion quartz crystal phase is precipitated after sintering, then the thermodynamic stability is judged as OK; if a high - thermal - expansion quartz crystal phase is precipitated after sintering, then the thermodynamic stability is judged as NG.

[0047] Acid and alkali corrosion resistance: The sintered LTCC material samples obtained in step (3) were respectively placed in an HCl solution with pH = 2 and an NaOH alkaline solution with pH = 12, and soaked at 50 °C for 24 hours. The changes in the weight, surface morphology, and dielectric properties of the samples before and after soaking were tested to determine the acid and alkali corrosion resistance of the material. If there were no obvious changes in the weight, surface morphology, and dielectric properties of the sample after soaking, it was determined that the acid and alkali corrosion resistance performance was OK; if the weight, surface morphology, and dielectric properties of the sample deteriorated after soaking, it was determined that the acid and alkali corrosion resistance performance was NG.

[0048] Dielectric properties: Based on the two - end short - circuited dielectric resonator method (JIS R1627), the microwave dielectric properties of the sintered LTCC material samples in step (3) at a temperature of 25 °C and a resonance frequency (10 - 18 GHz) were tested, including the relative dielectric constant and the loss tangent.

[0049] The examples (specimen Nos. 1 - 4) and comparative examples (specimen Nos. 5 - 13) of the present invention are shown in Table 1 and Table 2 respectively.

[0050] Table 1 Composition and performance parameters of each example Specimen No. 1 2 3 4 <![CDATA[SiO2]]> 40 50 60 70 <![CDATA[B2O3]]> 13 15 17 19 <![CDATA[Al2O3]]> 2 2 2 1 <![CDATA[ZrO2]]> 1 0.5 0 0 <![CDATA[Li2O]]> 03 0.3 0.3 0.6 <![CDATA[Na2O]]> 0.5 0.5 0.5 1 <![CDATA[K2O]]> 02 0.2 0.2 0.4 CaO 1 0.5 1 1 ZnO 0 0.5 0.5 1 MgO 0 0 0.5 0 Glass melting OK OK OK OK Fused silica 40 29 17 5 <![CDATA[Al2O3 filler]]> 2 1 1 1 <![CDATA[ZnAl2O4]]> 0 0.5 0 0 Sintering temperature (°C) 900 900 875 875 Water resistance OK OK OK OK Acid and alkali corrosion resistance OK OK OK OK Thermodynamic stability OK OK OK OK Relative dielectric constant 3.9 3.9 3.9 3.8 Loss tangent 0.0019 0.0014 0.0017 0.0015

[0051] Table 2 Composition and performance parameters of each comparative example Specimen No. 5 6 7 8 9 10 11 12 13 <![CDATA[SiO2]]> 70 65 65 65 70 60 60 35 60 <![CDATA[B2O3]]> 25 13 13 13 8 17 18 8 18 <![CDATA[Al2O3]]> 1 1 0 0 1 0 2 1 1.5 <![CDATA[ZrO2]]> 0 0 0 0 0 0.5 1 0 1 <![CDATA[Li2O]]> 0 0 0.3 0.3 0.6 0.3 1.05 0.15 0.3 <![CDATA[Na2O]]> 0 0 0.5 0.5 1 0.5 1.75 0.25 0.5 <![CDATA[K2O]]> 0 0 0.2 0.2 0.4 0.2 0.7 0.1 0.2 CaO 0 1 0 1 1 1 1 1 1 ZnO 0 0 0 0 1 0.5 0 0.5 1 MgO 0 0 0 0 0 0.5 0.5 0 0.5 Glass melting OK OK OK OK NG OK OK OK OK Fused silica 0 0 19 20 15 19 12 54 10 <![CDATA[Al2O3 filler]]> 4 20 1 0 1 0.5 1 0 6 <![CDATA[ZnAl2O4]]> 0 0 0 0 1 0 1 0 0 Sintering temperature (°C) 850 875 875 875 / 900 850 ＞950 875 Water resistance NG NG NG NG / NG NG OK OK Acid and alkali corrosion resistance NG NG NG NG / NG OK OK OK Thermodynamic stability NG OK OK OK OK NG OK OK OK Relative dielectric constant 3.8 4.6 3.9 4.0 / 37 42 / 4.2 Loss tangent 0.0031 0.0027 0.0021 0.0025 / 0.0011 0.0043 / 0.0018

[0052] It can be clearly seen from Table 1 that in the examples, the glass in the LTCC material specimen Nos. 1 - 4 provided by the present invention can be melted at a conventional temperature of 1500 - 1650 °C, and has good water resistance, acid and alkali resistance, thermodynamic stability, and dielectric properties.

[0053] In contrast, in Table 2, specimen Nos. 5 - 13 deviated from the LTCC material composition provided by the present invention, resulting in problems such as ineffective melting of the glass, poor water resistance of the LTCC material, poor acid and alkali corrosion resistance, high sintering temperature, poor thermodynamic stability during the sintering process, and deterioration of dielectric properties. Among them, specimen Nos. 5, 6, 7, 8, 10, and 11 had poor water resistance, and boric acid crystals precipitated due to moisture absorption after the LTCC material was exposed to air for 7 days. The XRD analysis results are as Figure 1 , the moisture content of the powder before moisture absorption tested at 120 °C was ≤2%, and this value was greater than 10% after moisture absorption; specimen Nos. 5 and 10 had poor thermodynamic stability during the sintering process, and quartz crystal phases with high thermal expansion precipitated, as Figure 2; Samples No. 5, 6, 7, 8, and 10 have poor acid and alkali corrosion resistance, and obvious corrosion appears after acid and alkali immersion; the glass of Sample No. 9 cannot be effectively melted under the conventional melting conditions of 1500 - 1650 °C; the sintering temperature of Sample No. 12 > 950 °C, and it cannot be co-fired with low melting point materials such as Au, Ag, and Cu; the dielectric constants of Samples No. 6, 11, and 13 > 4.0.

Claims

1. An ultra-low dielectric constant LTCC material, characterized in that: The ultra-low dielectric constant LTCC material includes aSiO2-bB2O3-cM2O3-dGO2-eR2O-fR'O glass + (xSiO2+yA) filler, wherein M is at least one of Al, Ga, Cr, Bi, Nd, Sm, and La, G is at least one of Zr and Ti, R is at least one of Li, Na, and K, R' is at least one of Ca, Sr, Mg, Zn, Mn, Ba, and Cu, and A is at least one of Al2O3, MgAl2O4, ZnAl2O4, mullite, zirconia, and cordierite. a, b, c, d, e, f, x, and y are mass percentages, 35%≤a≤78%, 9%≤b≤20%, 0.25%≤c≤4%, d≤2%, e≤2%, f≤2%, x≤50%, and y≤5%, and a+b+c+d+e+f+x+y=100%.

2. The ultra-low dielectric constant LTCC material according to claim 1, characterized in that, 0.25%≤d≤2%, 0.1%≤e≤2%, 0.1%≤f≤2%, 5%≤x≤50%, 1%≤y≤5%.

3. The ultra-low dielectric constant LTCC material according to claim 1 or 2, characterized in that: a+x≤85%, preferably, 65%<a+x≤85%.

4. The ultra-low dielectric constant LTCC material according to any one of claims 1 to 3, characterized in that The SiO2 filler is one or a mixture of α-quartz, α-cristobalite, β-tridymite, and fused quartz; preferably, the SiO2 filler is fused quartz.

5. The ultra-low dielectric constant LTCC material according to any one of claims 1 to 4, characterized in that The moisture content of the ultra-low dielectric constant LTCC material does not change significantly after being exposed to air for more than 7 days.

6. A method for preparing an ultra-low dielectric constant LTCC material according to any one of claims 1 to 5, characterized in that: The raw materials are weighed according to the composition of aSiO2-bB2O3-cM2O3-dGO2-eR2O-fR'O glass, melted at high temperature, quenched in water and ground to obtain glass powder, and the glass powder, SiO2 filler and A filler are mixed to obtain an ultra-low dielectric constant LTCC material.

7. The preparation method according to claim 6, characterized in that The particle size of the glass powder is 0.5 to 3 μm; the particle size of the filler is 0.5 to 4 μm.

8. A sintered body of an ultra-low dielectric constant LTCC material, characterized in that, The ultra-low dielectric constant LTCC material sintered body is obtained by sintering the ultra-low dielectric constant LTCC material according to any one of claims 1 to 5.

9. The sintered body of the ultra-low dielectric constant LTCC material according to claim 8, characterized in that, The relative dielectric constant of the ultra-low dielectric constant LTCC material sintered body is 3.8-5.0, preferably 3.8-4.0; the loss tangent is less than 0.003, preferably less than 0.002; and the weight change rate after immersion in water, strong acid and strong alkali solutions at 50°C for more than 24 hours is less than 0.1%.

10. A preparation method of a sintered body of an ultra-low dielectric constant LTCC material, characterized in that, The ultra-low dielectric constant LTCC material according to any one of claims 1 to 5 is sintered to obtain an ultra-low dielectric constant LTCC material sintered body; preferably, the sintering temperature is 850-950°C; more preferably, the sintering temperature is 850-920°C.

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