LTCC microwave dielectric material and preparation method thereof

Abstract

An LTCC microwave dielectric material, including the following components: a Ba.sub.5Si.sub.8O.sub.21+(1a) (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4+BaBSi glass; wherein 0.4a0.8, 0x1, 0y1, 0z1. By adjusting the amounts of Ba.sub.5Si.sub.8O.sub.21 and (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4, the temperature coefficient of resonance frequency can be adjusted to nearly zero. The material is suitable for the fields of high-frequency communication and radiofrequency. Also disclosed is a method for preparing the LTCC microwave dielectric material.

Claims

1. An LTCC microwave dielectric material, comprising the following components: a Ba.sub.5Si.sub.8O.sub.21+(1a) (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4+BaBSi glass; wherein 0.4a0.8, 0x1, 0y1, 0z1, and 1-x-y-z1.

2. The LTCC microwave dielectric material according to claim 1, wherein a weight of the BaBSi glass is 2-15% of a total weight of Ba.sub.5Si.sub.8O.sub.21 and (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4.

3. A method for preparing the LTCC microwave dielectric material according to claim 1, comprising the following steps: (1) weighing raw materials according to a stoichiometric ratio of Ba.sub.5Si.sub.8O.sub.21; transferring the raw materials weighed, zirconia balls, and deionized water into a ball mill pot; ball-milling for 4-12 h, removing a ball-milling product from the ball mill pot, followed by drying and sieving to obtain a powder; calcinating the powder at 1100-1250 C., holding the temperature for 1-5 h before cooling the powder to room temperature to obtain Ba.sub.5Si.sub.8O.sub.21 powder; (2) weighing raw materials according to a stoichiometric ratio of (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4; transferring the raw materials weighed, zirconia balls, and deionized water into a ball mill pot; planetary ball-milling for 4-12 h, removing a ball-milling product from the ball mill pot, followed by drying and sieving to obtain a powder; calcinating the powder at 700-1000 C., holding the temperature for 1-5 h before cooling the powder to room temperature to obtain (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4 powder; (3) putting the BaBSi glass, zirconia balls, and deionized water into a ball mill pot, ball-milling for 2-6 h; removing a ball-milling product from the ball mill pot, followed by drying to obtain BaBSi glass powder; (4) putting the Ba.sub.5Si.sub.8O.sub.21 powder obtained in step (1), the (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4 powder obtained in step (2), the BaBSi glass powder obtained in step (3), zirconia balls, and deionized water into a ball mill pot, ball-milling for 2-6 h; removing a ball-milling product from the ball mill pot, followed by drying and smashing to obtain a ceramic powder for preparing an LTCC microwave dielectric ceramic; (5) adding a PVA solution to the ceramic powder obtained in step (4) to granulate, followed by pressing to form a cylindrical block; sintering the cylindrical block at 850-900 C., holding the temperature for 0.5-3 h to obtain the LTCC microwave dielectric ceramic.

4. The method according to claim 3, wherein the BaBSi glass of step (3) is prepared by the steps of transferring weighed raw materials, zirconia balls, and deionized water into a ball mill pot, the raw materials consist of SiO.sub.2, H.sub.3BO.sub.3, BaCO.sub.3, Na.sub.2CO.sub.3, Li.sub.2CO.sub.3, CaCO.sub.3, SrCO.sub.3, K.sub.2CO.sub.3, Al.sub.2O.sub.3, MgO, and TiO.sub.2; planetary ball-milling for 1-4 h; removing a ball-milling product from the ball mill pot, followed by drying to obtain a dried powder; melting the dried powder at 1200-1500 C., holding the temperature for 1-3 h to obtain a high-temperature glass liquid, pouring the high-temperature glass liquid into deionized water to quench to obtain the BaBSi glass.

5. The method according to claim 3, wherein the sieving in steps (1) and (2) is sieving through a 200-mesh sieve.

6. The method according to claim 3, wherein in step (5), a weight of the PVA solution is 7-10 wt % of a weight of the ceramic powder.

7. The method according to claim 3, wherein the raw materials of step (2) are MgO, CaCO.sub.3, SrCO.sub.3, BaCO.sub.3, and WO.sub.3.

8. The method according to claim 3, wherein the raw materials of step (1) are BaCO.sub.3 and SiO.sub.2.

9. A method for preparing the LTCC microwave dielectric material according to claim 2, comprising the following steps: (1) weighing raw materials according to a stoichiometric ratio of Ba.sub.5Si.sub.8O.sub.21; transferring the raw materials weighed, zirconia balls, and deionized water into a ball mill pot; ball-milling for 4-12 h, removing a ball-milling product from the ball mill pot, followed by drying and sieving to obtain a powder; calcinating the powder at 1100-1250 C., holding the temperature for 1-5 h before cooling the powder to room temperature to obtain Ba.sub.5Si.sub.8O.sub.21 powder; (2) weighing raw materials according to a stoichiometric ratio of (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4; transferring the raw materials weighed, zirconia balls, and deionized water into a ball mill pot; planetary ball-milling for 4-12 h, removing a ball-milling product from the ball mill pot, followed by drying and sieving to obtain a powder; calcinating the powder at 700-1000 C., holding the temperature for 1-5 h before cooling the powder to room temperature to obtain (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4 powder; (3) putting the BaBSi glass, zirconia balls, and deionized water into a ball mill pot, ball-milling for 2-6 h; removing a ball-milling product from the ball mill pot, followed by drying to obtain BaBSi glass powder; (4) putting the Ba.sub.5Si.sub.8O.sub.21 powder obtained in step (1), the (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4 powder obtained in step (2), the BaBSi glass powder obtained in step (3), zirconia balls, and deionized water into a ball mill pot, ball-milling for 2-6 h; removing a ball-milling product from the ball mill pot, followed by drying and smashing to obtain a ceramic powder for preparing an LTCC microwave dielectric ceramic; (5) adding a PVA solution to the ceramic powder obtained in step (4) to granulate, followed by pressing to form a cylindrical block; sintering the cylindrical block at 850-900 C., holding the temperature for 0.5-3 h to obtain the LTCC microwave dielectric ceramic.

10. The method according to claim 9, wherein the BaBSi glass of step (3) is prepared by the steps of transferring weighed raw materials, zirconia balls, and deionized water into a ball mill pot, the raw materials consist of SiO.sub.2, H.sub.3BO.sub.3, BaCO.sub.3, Na.sub.2CO.sub.3, Li.sub.2CO.sub.3, CaCO.sub.3, SrCO.sub.3, K.sub.2CO.sub.3, Al.sub.2O.sub.3, MgO, and TiO.sub.2; planetary ball-milling for 1-4 h; removing a ball-milling product from the ball mill pot, followed by drying to obtain a dried powder; melting the dried powder at 1200-1500 C., holding the temperature for 1-3 h to obtain a high-temperature glass liquid, pouring the high-temperature glass liquid into deionized water to quench to obtain the BaBSi glass.

11. The method according to claim 9, wherein the sieving in steps (1) and (2) is sieving through a 200-mesh sieve.

12. The method according to claim 9, wherein in step (5), a weight of the PVA solution is 7-10 wt % of a weight of the ceramic powder.

13. The method according to claim 9, wherein the raw materials of step (2) are MgO, CaCO.sub.3, SrCO.sub.3, BaCO.sub.3, and WO.sub.3.

14. The method according to claim 9, wherein the raw materials of step (1) are BaCO.sub.3 and SiO.sub.2.

Description

DETAILED DESCRIPTION OF EMBODIMENTS

(1) The objectives, technical solutions, and beneficial effects of the present disclosure will be described below with reference to the embodiments.

(2) The LTCC microwave dielectric materials of the embodiments comprise the following components: a Ba.sub.5Si.sub.8O.sub.21+(1a) (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4+BaBSi glass; wherein 0.4a0.8, 0x1, 0y1, 0z1. The weight of the BaBSi glass is 2-15% (b %) of the total weight of Ba.sub.5Si.sub.8O.sub.21 and (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4.

(3) The method for preparing the LTCC microwave dielectric materials of the embodiments comprises the following steps: (1) Weighing raw materials (BaCO.sub.3 and SiO.sub.2) according to the stoichiometric ratio of Ba.sub.5Si.sub.8O.sub.21; transferring the raw materials weighed, zirconia balls, and deionized water into a ball mill pot; planetary ball-milling for 4-12 h, removing the ball-milling product from the ball mill pot, followed by drying and sieving through a 200-mesh sieve to obtain a powder; calcinating the powder in an alumina crucible in a muffle furnace at 1100-1250 C., holding the temperature for 1-5 h before cooling the powder to room temperature to obtain Ba.sub.5Si.sub.8O.sub.21 powder. (2) Weighing raw materials (MgO, CaCO.sub.3, SrCO.sub.3, BaCO.sub.3, and WO.sub.3) according to the stoichiometric ratio of (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4 (0x1, 0y1, 0z1); transferring the raw materials weighed, zirconia balls, and deionized water into a ball mill pot; planetary ball-milling for 4-12 h; removing the ball-milling product from the ball mill pot, followed by drying and sieving through a 200-mesh sieve to obtain a powder; calcinating the powder in a muffle furnace at 700-1000 C., holding the temperature for 1-5 h before cooling the powder to room temperature to obtain (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4 powder. (3) Transferring weighed raw materials (45.8 wt % SiO.sub.2, 39.6 wt % H.sub.3BO.sub.3, 5.3 wt % BaCO.sub.3, 1.6 wt % Na.sub.2CO.sub.3, 0.7 wt % Li.sub.2CO.sub.3, 1.5 wt % CaCO.sub.3, 1.1 wt % SrCO.sub.3, 1.9 wt % K.sub.2CO.sub.3, 1.2 wt % Al.sub.2O.sub.3, 0.8 wt % MgO, 0.5 wt % TiO.sub.2), zirconia balls, and deionized water into a ball mill pot; planetary ball-milling for 1-4 h; removing the ball-milling product from the ball mill pot, followed by drying to obtain a dried powder; melting the dried powder in an alumina crucible in a high-temperature furnace at 1200-1500 C., holding the temperature for 1-3 h to obtain a high-temperature glass liquid, pouring the high-temperature glass liquid into deionized water to quench to obtain a BaBSi glass. Putting the BaBSi glass, zirconia balls, and deionized water into a ball mill pot, planetary ball-milling for 2-6 h; removing the ball-milling product from the ball mill pot, followed by drying to obtain BaBSi glass powder. (4) Weighing the Ba.sub.5Si.sub.8O.sub.21 powder, the (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4 powder, and the BaBSi glass powder described above according to the ratio specified by a Ba.sub.5Si.sub.8O.sub.21+(1a) (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4+b wt % BaBSi glass; wherein 0.4a0.8, 2b15. Putting the weighed powder mixture, zirconia balls, and deionized water into a ball mill pot, planetary ball-milling for 2-6 h; removing the ball-milling product from the ball mill pot, followed by drying and smashing to obtain a ceramic powder for preparing an LTCC microwave dielectric ceramic. (5) Adding 7-10 wt % of a PVA solution to the ceramic powder to granulate, followed by pressing to form a cylindrical block; sintering the cylindrical block at 850-900 C., holding the temperature for 0.5-3 h to obtain the LTCC microwave dielectric ceramic.

(4) The components and properties of the LTCC microwave dielectric materials of the embodiments are shown in Table 1. The dielectric constant and the Qf value are obtained by a parallel-plate reflection method with a network analyzer. f value is calculated by the formula

(5) $f=\frac{f2-f1}{f1.Math.\left(T2-T1\right)},$
wherein T2 and T1 are 80 C. and 25 C. respectively, f2 and f1 are the resonance frequencies of the sample at temperatures T2 and T1 respectively.

(6) TABLE-US-00001 TABLE 1 Components and Microwave Dielectric Properties of Embodiments Sintering Qf temperature Dielectric value f Embodiment x y z a b ( C.) constant (GHz) (ppm/ C.) 1 1 0 0 0.6 2 900 9.7 18700 8.9 2 0 1 0 0.5 7 860 8.9 24300 1.3 3 0 0 1 0.6 8 880 8.3 17400 3.2 4 0 0 1 0.7 6 880 7.8 16600 +4.1 5 0 0 0 0.8 15 850 6.5 12000 +1.6 6 0 0.5 0 0.5 9 870 7.3 17800 +6.7 7 0.5 0 0.5 0.7 12 850 6.9 15800 2.9

(7) According to Table 1, the LTCC microwave dielectric ceramics obtained in this disclosure have relatively low dielectric constants. By adjusting the amounts of Ba.sub.5Si.sub.8O.sub.21 and (Mg.sub.xCa.sub.ySr.sub.zBa.sub.1-x-y-z)WO.sub.4, the temperature coefficient of resonance frequency can be adjusted to nearly zero. The material is thus suitable for the fields of high-frequency communication and radiofrequency.

(8) Finally, it should be noted that the embodiments are only used to illustrate the technical solutions of the present disclosure. They do not intend to limit the protection scope of the present disclosure. Although the present disclosure has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present disclosure can be modified without departing from the spirit and the scope of the present disclosure.