LOW-DIELECTRIC WOLLASTONITE BASED LOW-TEMPERATURE CO-FIRED CERAMIC MATERIAL AND PREPARATION METHOD THEREFOR

Abstract

The present disclosure relates to the technical field of electronic materials. A low-dielectric wollastonite based low-temperature co-fired ceramic material and a preparation method therefor are provided. The formula of the ceramic material is: Ca.sub.xSiO.sub.3+awt % SiO.sub.2+bwt % R.sub.2O+cwt % Bi.sub.2O.sub.3+dwt % B.sub.2O.sub.3+ewt % MO, wherein 0.9?x?1.1, 0<a?30, 1?b?5, 0<c?3, 0<d?6, 0?e?10, R.sub.2O is at least one of Li.sub.2O and K.sub.2O, and MO is one or more of ZnO, MgO, BaO, CoO, CuO, La.sub.2O.sub.3 and MnO.sub.2. The low-temperature co-fired ceramic material provided by the present disclosure satisfies the requirements of low dielectric, low loss and low-temperature sintering, and can be applied to the fields of millimeter wave LTCC devices and the like.

Claims

1. A low-dielectric wollastonite based low-temperature co-fired ceramic material, wherein a formula expression of the low-temperature co-fired ceramic material is: Ca.sub.xSiO.sub.3+awt % SiO.sub.2+bwt % R.sub.2O+cwt % Bi.sub.2O.sub.3+dwt % B.sub.2O.sub.3+ewt % MO, wherein 0.9?x?1.1, 0<a?30, 1?b?5, 0<c?3, 0<d?6, and 0?e?10, a, b, c, d, and e are mass fractions of SiO.sub.2, RO, Bi.sub.2O.sub.3, B.sub.2O.sub.3, and MO phases in Ca.sub.xSiO.sub.3 respectively, R.sub.2O is at least one of Li.sub.2O and K.sub.2O, MO is one or more of ZnO, MgO, BaO, CoO, CuO, La.sub.2O.sub.3, and MnO.sub.2, and SiO.sub.2 is at least one of quartz and fused quartz.

2. The low-dielectric wollastonite based low-temperature co-fired ceramic material according to claim 1, wherein a composition of the main phase ceramic material is: Ca.sub.xSiO.sub.3, and 0.9?x?1.0.

3. The low-dielectric wollastonite based low-temperature co-fired ceramic material according to claim 1, wherein the SiO.sub.2 is fused quartz.

4. A preparation method for the low-dielectric wollastonite based low-temperature co-fired ceramic material according to claim 1, comprising: 1) synthesis of a main phase ceramics Ca.sub.xSiO.sub.3: weighing raw materials CaCO.sub.3 and SiO.sub.2 according to a chemical formula Ca.sub.xSiO.sub.3 metric ratio, using deionized water as a solvent, and ball milling and mixing for 16 to 24 hours, drying and then sieving through a 40-mesh sieve, crushing evenly and then placing into an alumina crucible, calcining at 900? C. to 1300? C. for 2 to 4 hours to synthesize the main phase ceramics, and grinding as a ceramic base material for later use; 2) synthesis of a sintering aid: weighing raw materials Li.sub.2CO.sub.3, K.sub.2CO.sub.3, Bi.sub.2O.sub.3, B.sub.2O.sub.3 or H.sub.3BO.sub.3, ZnO, MgO or Mg(OH).sub.2, BaCO.sub.3, CoO or Co.sub.2O.sub.3, CuO, La.sub.2O.sub.3, and MnO.sub.2/MnCO.sub.3 according to relative mass fraction ratio a of bwt % RO+cwt % Bi.sub.2O.sub.3+dwt % B.sub.2O.sub.3+ewt % MO, adding absolute ethanol at a mass ratio of the mixture to absolute ethanol of 1:1 to 1.5, mixing the mixture and absolute ethanol by a wet method for 16 to 24 hours and then drying at 80? C., sieving the dried material through a 40-mesh sieve, placing it into an alumina crucible, calcining it at 500? C. to 700? C. for 2 to 4 hours, grinding and then using it as a sintering aid for later use, wherein 1?b?5, 0<c?3, 0<d?6, 0?e?10, and b, c, d, and e are mass fractions of RO, Bi.sub.2O.sub.3, B.sub.2O.sub.3, and MO phases in Ca.sub.xSiO.sub.3 respectively; and 3) mixing the prepared main phase ceramics Ca.sub.xSiO.sub.3SiO.sub.2, and oxide sintering aid according to the mass ratio of Ca.sub.xSiO.sub.3+awt % SiO.sub.2+bwt % RO+cwt % Bi.sub.2O.sub.3+dwt % B.sub.2O.sub.3+ewt % MO, using ZrO.sub.2 balls as a grinding medium, using ethanol as a solvent, and drying the mixture after ball milling for 16 to 24 hours, adding a polyvinyl alcohol binder with a weight content of 5% to 8% for grinding and granulation, after sieving, pressing under a pressure of 80 MPa to 120 MPa into a green body with a diameter of 20 mm and a thickness of 10 mm, and sintering in an air atmosphere of 850? C. to 950? C. for 1 to 3 hours to obtain the low-dielectric wollastonite based low-temperature co-fired ceramic material, wherein a, b, c, d, and e are mass fractions of SiO.sub.2, RO, Bi.sub.2O.sub.3, B.sub.2O.sub.3, and MO phases in Ca.sub.xSiO.sub.3 respectively.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which constitute a part of the present application, are included to provide a further understanding of the present application. The illustrative embodiments and description of the present application are used to explain the present application and do not constitute a limitation of the present application.

[0026] FIG. 1 is an XRD diffraction pattern of ceramics in Example 2.

[0027] FIG. 2 is an SEM scanning electron microscope image of a fired ceramic sample in Example 4.

DESCRIPTION OF THE EMBODIMENTS

[0028] The embodiments of the disclosure are provided in detail as follows. Examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to explain the disclosure, but should not be construed as limiting the disclosure.

[0029] In order to make the objectives, technical solutions, and advantages of the disclosure clearer and more comprehensible, the disclosure is further described in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein serve to explain the disclosure merely and are not used to limit the disclosure.

Example 1

[0030] 1) Main phase synthesis: raw materials CaCO.sub.3 and quartz were weighed according to the chemical formula Ca.sub.0.98SiO.sub.3 metric ratio, using deionized water as the solvent, ball milled and mixed for 24 hours, dried and sieved through a 40 mesh sieve, crushed evenly, put into an alumina crucible, and then calcined at 1200? C. for 3 hours to synthesize the main phase ceramic.

[0031] 2) Synthesis of a sintering aid: raw materials such as Li.sub.2CO.sub.3, Bi.sub.2O.sub.3, H.sub.3BO.sub.3, and ZnO were weighed according to the mass ratio of fraction 3 wt % Li.sub.2O+2 wt % Bi.sub.2O.sub.3+3 wt % B.sub.2O.sub.3+3 wt % ZnO relative to the main phase ceramic, absolute ethanol was added at a mass ratio of 1:1 between the mixture and absolute ethanol, the mixture was mixed by a wet method for 16 hours and then dried at 80? C., and the dried mixture was sieved through a 40-mesh sieve, put into an alumina crucible, calcined at 600? C. for 3 hours, and then ground and used as a sintering aid for later use.

[0032] 3) Fused quartz accounting for 3.0 wt % of the mass percentage of the main phase ceramics and the sintering aid synthesized in the previous step were added to the main phase ceramics Ca.sub.0.98SiO.sub.3 for mixing. ZrO.sub.2 balls were used as a grinding medium and ethanol was used as the solvent. The ball-milled mixture was dried for 16 hours, added with a polyvinyl alcohol binder with a weight content of 8% for grinding and granulation, sieved, and then pressed under a pressure of 100 MPa to form a green body with a diameter of 20 mm and a thickness of 10 mm. The low-temperature co-fired ceramic material was obtained by sintering in an air atmosphere at 850? C. for 3 hours and its dielectric properties were tested.

Example 2

[0033] 1) Main phase synthesis: raw materials CaCO.sub.3 and quartz were weighed according to the chemical formula CaSiO.sub.3 metric ratio, using deionized water as the solvent, ball milled and mixed for 24 hours, dried and sieved through a 40 mesh sieve, crushed evenly, put into an alumina crucible, and then calcined at 1250? C. for 3 hours to synthesize the main phase ceramic.

[0034] 2) Synthesis of a sintering aid: raw materials such as Li.sub.2CO.sub.3, K.sub.2CO.sub.3, Bi.sub.2O.sub.3, H.sub.3BO.sub.3, BaCO.sub.3, and MnO.sub.2 were weighed according to the mass fraction ratio of 1.5 wt % Li.sub.2O+1 wt % K.sub.2O+0.5 wt % Bi.sub.2O.sub.3+2.5 wt % B.sub.2O.sub.3+3 wt % BaO+2 wt % MnO.sub.2 relative to the main phase ceramic, absolute ethanol was added at a mass ratio of 1:1 between the mixture and absolute ethanol, the mixture was mixed by a wet method for 16 hours and then dried at 80? C., and the dried mixture was sieved through a 40-mesh sieve, put into an alumina crucible, calcined at 650? C. for 3 hours, and then ground and used as a sintering aid for later use.

[0035] 3) Fused quartz accounting for 3.5 wt % of the mass percentage of the main phase ceramics and the sintering aid synthesized in the previous step were added to the main phase ceramics CaSiO.sub.3 for mixing. ZrO.sub.2 balls were used as a grinding medium and ethanol was used as the solvent. The ball-milled mixture was dried for 16 hours, added with a polyvinyl alcohol binder with a weight content of 8% for grinding and granulation, sieved, and then pressed under a pressure of 100 MPa to form a green body with a diameter of 20 mm and a thickness of 10 mm. The low-temperature co-fired ceramic material was obtained by sintering in an air atmosphere at 900? C. for 3 hours and its dielectric properties were tested. FIG. 1 shows the XRD pattern of the ceramics after sintering, and the main phase of the ceramics is CaSiO.sub.3 and a small amount of SiO.sub.2 phase.

Example 3

[0036] 1) Main phase synthesis: raw materials CaCO.sub.3 and quartz were weighed according to the chemical formula Ca.sub.1.02SiO.sub.3 metric ratio, using deionized water as the solvent, ball milled and mixed for 24 hours, dried and sieved through a 40 mesh sieve, crushed evenly, put into an alumina crucible, and then calcined at 1300? C. for 3 hours to synthesize the main phase ceramic.

[0037] 2) Synthesis of a sintering aid: raw materials such as Li.sub.2CO.sub.3, Bi.sub.2O.sub.3, H.sub.3BO.sub.3, and MgO were weighed according to the mass fraction ratio of 2.5 wt % Li.sub.2O+1 wt % Bi.sub.2O.sub.3+2.5 wt % B.sub.2O.sub.3+2 wt % MgO relative to the main phase ceramic, absolute ethanol was added at a mass ratio of 1:1 between the mixture and absolute ethanol, the mixture was mixed by a wet method for 16 hours and then dried at 80? C., and the dried mixture was sieved through a 40-mesh sieve, put into an alumina crucible, calcined at 700? C. for 3 hours, and then ground and used as a sintering aid for later use.

[0038] 3) Fused quartz accounting for 5.0 wt % of the mass percentage of the main phase ceramics and the sintering aid synthesized in the previous step were added to the main phase ceramics Ca.sub.1.02SiO.sub.3 for mixing. ZrO.sub.2 balls were used as a grinding medium and ethanol was used as the solvent. The ball-milled mixture was dried for 16 hours, added with a polyvinyl alcohol binder with a weight content of 8% for grinding and granulation, sieved, and then pressed under a pressure of 100 MPa to form a green body with a diameter of 20 mm and a thickness of 10 mm. The low-temperature co-fired ceramic material was obtained by sintering in an air atmosphere at 850? C. for 3 hours and its dielectric properties were tested.

Example 4

[0039] 1) Main phase synthesis: raw materials CaCO.sub.3 and quartz were weighed according to the chemical formula CaSiO.sub.3 metric ratio, using deionized water as the solvent, ball milled and mixed for 24 hours, dried and sieved through a 40 mesh sieve, crushed evenly, put into an alumina crucible, and then calcined at 1200? C. for 3 hours to synthesize the main phase ceramic.

[0040] 2) Synthesis of a sintering aid: raw materials such as Li.sub.2CO.sub.3, Bi.sub.2O.sub.3, H.sub.3BO.sub.3, La.sub.2O.sub.3, and CuO were weighed according to the mass fraction ratio of 4 wt % Li.sub.2O+1.5 wt % Bi.sub.2O.sub.3+4 wt % B.sub.2O.sub.3+1 wt % La.sub.2O.sub.3+2 wt % CuO relative to the main phase ceramic, absolute ethanol was added at a mass ratio of 1:1 between the mixture and absolute ethanol, the mixture was mixed by a wet method for 16 hours and then dried at 80? C., and the dried mixture was sieved through a 40-mesh sieve, put into an alumina crucible, calcined at 600? C. for 3 hours, and then ground and used as a sintering aid for later use.

[0041] 3) Fused quartz accounting for 2.0 wt % of the mass percentage of the main phase ceramics and the sintering aid synthesized in the previous step were added to the main phase ceramics CaSiO.sub.3 for mixing. ZrO.sub.2 balls were used as a grinding medium and ethanol was used as the solvent. The ball-milled mixture was dried for 16 hours added with a polyvinyl alcohol binder with a weight content of 8% for grinding and granulation, sieved and then pressed under a pressure of 100 MPa to form a green body with a diameter of 20 mm and a thickness of 10 mm. The low-temperature co-fired ceramic material was obtained by sintering in an air atmosphere at 880? C. for 3 hours and its dielectric properties were tested. FIG. 2 is a scanning electron microscope photo of a cross-section of a ceramic sample. It can be seen that this low-temperature co-fired ceramics have better compactness.

Example 5

[0042] 1) Main phase synthesis: raw materials CaCO.sub.3 and fused quartz were weighed according to the chemical formula Ca.sub.0.95SiO.sub.3 metric ratio, using deionized water as the solvent, ball milled and mixed for 24 hours, dried and sieved through a 40 mesh sieve, crushed evenly, put into an alumina crucible, and then calcined at 1100? C. for 3 hours to synthesize the main phase ceramic.

[0043] 2) Synthesis of a sintering aid: raw materials such as Li.sub.2CO.sub.3, Bi.sub.2O.sub.3, H.sub.3BO.sub.3, CoO, and CuO were weighed according to the mass fraction ratio of 3.75 wt % Li.sub.2O+2.5 wt % Bi.sub.2O.sub.3+3.75 wt % B.sub.2O.sub.3+1 wt % CoO relative to the main phase ceramic, absolute ethanol was added at a mass ratio of 1:1 between the mixture and absolute ethanol, the mixture was mixed by a wet method for 16 hours and then dried at 80? C. and the dried mixture was sieved through a 40-mesh sieve, put into an alumina crucible, calcined at 650? C. for 3 hours, and then ground and used as a sintering aid for later use.

[0044] 3) Fused quartz accounting for 10.0 wt % of the mass percentage of the main phase ceramics and the sintering aid synthesized in the previous step were added to the main phase ceramics Ca.sub.0.95SiO.sub.3 for mixing. ZrO.sub.2 balls were used as a grinding medium and ethanol was used as the solvent. The ball-milled mixture was dried for 16 hours, added with a polyethylene binder with a weight content of 8% for grinding and granulation, sieved, and then pressed under a pressure of 100 MPa to form a green body with a diameter of 20 mm and a thickness of 10 mm. The low-temperature co-fired ceramic material was obtained by sintering in an air atmosphere at 850? C. for 3 hours and its dielectric properties were tested.

Example 6

[0045] Quartz with a mass percentage of 10.0 wt % of the main phase ceramics and the sintering aid synthesized in Example 5 were added to the main phase ceramics Ca.sub.0.95SiO.sub.3 synthesized in Example 5 for mixing. ZrO.sub.2 balls were used as a grinding medium and ethanol was used as the solvent. The ball-milled mixture was dried for 16 hours, added with a polyvinyl alcohol binder with a weight content of 8% for grinding and granulation, sieved, and then pressed under a pressure of 100 MPa to form a green body with a diameter of 20 mm and a thickness of 10 mm. The low-temperature co-fired ceramic material was obtained by sintering in an air atmosphere at 880? C. for 3 hours and its dielectric properties were tested.

Example 7

[0046] Fused quartz with a mass percentage of 7.0 wt % of the main phase ceramics and the sintering aid synthesized in Example 2 were added to the main phase ceramics CaSiO.sub.3 synthesized in Example 5 for mixing. ZrO.sub.2 balls were used as a grinding medium and ethanol was used as the solvent. The ball-milled mixture was dried for 16 hours, added with a polyvinyl alcohol binder with a weight content of 8% for grinding and granulation, sieved, and then pressed under a pressure of 100 MPa to form a green body with a diameter of 20 mm and a thickness of 10 mm. The low-temperature co-fired ceramic material was obtained by sintering in an air atmosphere at 850? C. for 3 hours and its dielectric properties were tested.

Comparative Example 1

[0047] The main phase ceramics CaSiO.sub.3 synthesized in Example 2 and the sintering aid synthesized in Example 2 were mixed. ZrO.sub.2 balls were used as a grinding medium and ethanol was used as the solvent. The ball-milled mixture was dried for 16 hours, added with a polyvinyl alcohol binder with a weight content of 8% for grinding and granulation, sieved, and then pressed under a pressure of 100 MPa to form a green body with a diameter of 20 mm and a thickness of 10 mm. The low-temperature co-fired ceramic material was obtained by sintering in an air atmosphere at 930? C. for 3 hours and its dielectric properties were tested.

[0048] Table 1 is the material dielectric property test results corresponding to the Comparative Example and Examples 1 to 7. Herein, the dielectric properties are measured using the Agilent 8719ET network analyzer to test the dielectric constant & and the Q?f value. The frequency temperature coefficient of the sample tf=(f110-f25)/(f25?85) is calculated and determined, where f110 and f25 are the resonant center frequencies of the sample at 110? C. and 25? C. respectively.

TABLE-US-00001 TABLE 1 Dielectric property test results of Examples and Comparative Example No. ?.sub.r Q ? f (GHz) ?.sub.f(ppm/? C.) 1 6.68 24200 ?25.9 2 6.85 22400 ?30.3 3 7.26 21600 ?34.8 4 6.92 22870 ?28.6 5 6.40 21730 ?23.7 6 6.45 20350 ?25.2 7 6.60 20900 ?27.5 Comparative Example 1 7.04 18580 ?38.2

[0049] The low-temperature co-fired ceramic materials listed in the above table have a dielectric constant less than 7.5, a Q?f value greater than 20,000 GHz, and an absolute value of frequency temperature coefficient less than 35 ppm/? C. The requirements of low dielectric constant, low loss, and lower frequency temperature coefficient required for a millimeter wave device are satisfied. Compared with the Comparative Example, the introduction of fused quartz may not only reduce the sintering temperature, but also increase the Q?f value of the material and improve the frequency temperature coefficient.

[0050] It should be noted that in the description of the disclosure, the terms include, comprise, etc. are intended to cover non-exclusive inclusion, and also include processes, methods, raw materials, etc. of other elements that are not explicitly listed. An embodiment or a particular embodiment or the like means that a particular feature, structure, material or characteristic described in connection with the embodiment is included in at least one embodiment of the disclosure.

[0051] Therefore, although specific embodiments have been used to illustrate the disclosure above, it can be understood that the abovementioned embodiments are used to understand the methods and core matters of the disclosure and cannot be understood as limitations of the disclosure. A person having ordinary skill in the art may make changes, corrections, substitutions, and modifications to the abovementioned embodiments within the scope of the disclosure without departing from the principle and purpose of the disclosure, and any simple corrections, equivalent changes, and modifications made to the above embodiments based on the technical essence of the disclosure still fall within the protection scope of the disclosure.