LOW TEMPERATURE CO-FIRED DIELECTRIC MATERIAL AND PREPARATION METHOD THEREOF

Abstract

Disclosed is a low temperature co-fired dielectric material with an adjustable dielectric constant, wherein it comprises a zirconia main phase and a silicon-based amorphous filler, a weight ratio of the zirconia main phase to the silicon-based amorphous filler is 40-65: 35-60; a weight percentage of SiO.sub.2. in the silicon-based amorphous filler is ≥50%. The dielectric constant of low temperature co-fired dielectric material can be continuously adjusted in a wide range of 7-12, the dielectric loss can be as low as 0.1% at 1 MHz. The material system can be sintered at 800-900° C. and co-fired with silver electrode. It can be used as the low temperature co-fired dielectric material. The invention also discloses a method for preparing the low temperature co-fired dielectric material with an adjustable dielectric constant.

Claims

1. A low temperature co-fired dielectric material with an adjustable dielectric constant, wherein it comprises a zirconia main phase and a silicon-based amorphous filler, a weight ratio of the zirconia main phase to the silicon-based amorphous filler is 40-65: 35-60; a weight percentage of SiO.sub.2 in the silicon-based amorphous filler is ≥50%.

2. The low temperature co-fired dielectric material according to claim 1, wherein the low temperature co-fired dielectric material comprises the following components in percentage by weight: ZrO.sub.2 40-65%, SiO.sub.2 27.03-46.33%, Na.sub.2O 0.27-0.46%, K.sub.2O 1.23-2.11%, CaO 0.73-1.26% and B.sub.2O.sub.3 5.73-9.83%.

3. The low temperature co-fired dielectric material according to claim 1, wherein the zirconia main phase is crystalline or amorphous.

4. The low temperature co-fired dielectric material according to claim 2, wherein the zirconia main phase is crystalline or amorphous.

5. The low temperature co--fired dielectric material according to claim 1, wherein the silicon-based amorphous filler is glass or a mixture of amorphous materials.

6. The low temperature co-fired dielectric material according to claim 2, wherein the silicon-based amorphous filler is glass or a mixture of amorphous materials.

7. The low temperature co-fired dielectric material according to claim 2, wherein the silicon-based amorphous filler has an atomic ratio of Na: K=1:2-4.

8. The low temperature co-fired dielectric material according to claim 2, wherein Al element in the silicon-based amorphous filler has a weight percentage of less than or equal to 0.01%.

9. The low temperature co-fired dielectric material according to claim 2, wherein the ZrO.sub.2 has a particle size ranging from 0.5 μm to 10 μm; preferably, the ZrO.sub.2 has a particle size ranging from 1 μm to 5 μm.

10. The low temperature co-fired dielectric material according to claim 1, wherein the silicon-based amorphous filler is prepared by steps of S1: dissolving ethyl orthosilicate in a mixture of alcohol and deionized water to obtain a solution; S2: adjusting the pH of the solution to 1-3; S3: adding a salt of an element present in a glass powder to the solution; heating the solution at 60-80° C. and stirring thoroughly; and S4: adjusting the pH of the solution to 6-8 to obtain a gel; drying the gel and calcinating at 600-750° C. to obtain the silicon-based amorphous filler.

11. The low temperature co-fired dielectric material according to claim 1, wherein in S1 a volume ratio of ethyl orthosilicate to alcohol to deionized water is 1 to 5-15 to 1.

12. A method for preparing the low temperature co-fired dielectric material according to claim 1, wherein the method comprises mixing the silicon-based amorphous filler and zirconia main phase, performing ball-milling for 6-24 hours; and sintering at 800-900° C. to obtain the low temperature co-fired dielectric material.

13. A method for preparing the low temperature co-fired dielectric material according to claim 2, wherein the method comprises mixing the silicon-based amorphous filler and zirconia main phase, performing ball-milling for 6-24 hours; and sintering at 800-900° C. to obtain the low temperature co-fired dielectric material.

14. A method for preparing the low temperature co-fired dielectric material according to claim 3, wherein the method comprises mixing the silicon-based amorphous filler and zirconia main phase, performing ball-milling for 6-24 hours; and sintering at 800-900° C. to obtain the low temperature co-fired dielectric material.

15. A method for preparing the low temperature co-fired dielectric material according to claim 5, wherein the method comprises mixing the silicon-based amorphous filler and zirconia main phase, performing ball-milling for 6-24 hours; and sintering at 800-900° C. to obtain the low temperature co-fired dielectric material.

16. A method for preparing the low temperature co-fired dielectric material according to claim 7, wherein the method comprises mixing the silicon-based amorphous filler and zirconia main phase, performing ball-milling for 6-24 hours; and sintering at 800-900° C. to obtain the low temperature co-fired dielectric material.

17. A method for preparing the low temperature co-fired dielectric material according to claim 8, wherein the method comprises mixing the silicon-based amorphous filler and zirconia main phase, performing ball-milling for 6-24 hours; and sintering at 800-900° C. to obtain the low temperature co-fired dielectric material.

18. A method for preparing the low temperature co-fired dielectric material according to claim 9, wherein the method comprises mixing the silicon-based amorphous filler and zirconia main phase, performing ball-milling for 6-24 hours; and sintering at 800-900° C. to obtain the low temperature co-fired dielectric material.

19. A method for preparing the low temperature co-fired dielectric material according to claim 10, wherein the method comprises mixing the silicon-based amorphous filler and zirconia main phase, performing ball-milling for 6-24 hours; and sintering at 800-900° C. to obtain the low temperature co-fired dielectric material.

20. A method for preparing the low temperature co-fired dielectric material according to claim 11, wherein the method comprises mixing the silicon-based amorphous filler and zirconia main phase, performing ball-milling for 6-24 hours; and sintering at 800-900° C. to obtain temperature co-fired dielectric material.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 is a diagram showing the dielectric properties of the samples described in Examples 1-4 (at 1 MHz).

[0028] FIG. 2(a) is the SEM image of a cross-section of the green sheet formed by dry pressing of the silver electrode and powder in example 3 after co-firing at 850° C.

[0029] FIG. 2(b) is a diagram showing the silver content at the points shown in FIG. 2(a).

DETAILED DESCRIPTION OF PREFERRED EXAMPLES

[0030] In order to better illustrate the objective, technical solutions and advantages of the present invention, the present invention will be further described below through specific examples.

Example 1

[0031] An example of the method for preparing the low temperature co-fired dielectric material of the present invention includes the following steps:

[0032] 9.3 mL ethyl orthosilicate was dissolved in a mixture of alcohol (100 mL) and deionized water (9.3 mL); to facilitate hydrolysis, nitric acid was added to adjust the pH of the solution to about 1 with stirring. After the solution turned clear, 0.07 g NaNO.sub.3, 0.24 g KNO.sub.3, 0.28 g Ca(NO.sub.3).sub.2.4H.sub.2O and 0.92 g of a HBO.sub.3 solution were added to the solution, stirred vigorously, and heated at 75° C. Then, ammonia water was added to adjust the pH to about 7 to form a gel. After drying the gel obtained, it was calcined at 700° C. for 2 h to obtain a silicon-based amorphous filler. Finally, 49.81% of ZrO.sub.2 (particle size is 5 μm) and 50.19% of the silicon-based amorphous filler were weighed, and were ground and mixed at the ball mill for 18 hours. After drying, the mixture was pressed into a sheet at 7 MPa and sintered at 850° C. to obtain the low temperature co-fired ceramic material.

[0033] The dielectric properties of the low temperature co-fired dielectric material prepared in this example are shown in FIG. 1. The dielectric constant was 8.89 at 1 MHz, the dielectric loss was 0.0012 at 1 MHz. The low temperature co-fired dielectric material described in this example was tightly bonded to a silver electrode after co-firing. No delamination, warpage, etc. occurred.

Example 2

[0034] An example of the method for preparing the low temperature co-fired dielectric material of the present invention includes the following steps:

[0035] 9.3 mL ethyl orthosilicate was dissolved in a mixture of alcohol (100 mL) and deionized water (9.3 mL); to facilitate hydrolysis, nitric acid was added to adjust the pH of the solution to about 1 with stirring. After the solution turned clear, 0.07 g NaNO.sub.3, 0.24 g KNO.sub.3, 0.28 g Ca(NO.sub.3).sub.2.4H.sub.2O and 0.92 g of a HBO.sub.3 solution were added to the solution, stirred vigorously, and heated at 80° C. Then, ammonia water was added to adjust the pH to about 7 to form a gel. After drying the gel obtained, it was calcined at 700° C. for 2 h to obtain a silicon-based amorphous filler. Finally, 55% of ZrO.sub.2 (particle size is 5 μm) and 45% of the silicon-based amorphous filler were weighed, and were ground and mixed at the ball mill for 15 hours. After drying, the mixture was pressed into a sheet at 7 MPa and sintered at 850° C. to obtain the low temperature co-fired ceramic material.

[0036] The dielectric properties of the low temperature co-fired dielectric material prepared in this example are shown in FIG. 1. The dielectric constant was 10.48 at 1 MHz, the dielectric loss was 0.0011 at 1 MHz. The low temperature co-fired dielectric material described in this example was tightly bonded to a silver electrode after co-firing. No delamination, warpage, etc. occurred.

Example 3

[0037] An example of the preparation method of the low temperature co-fired dielectric material of the present invention includes the following steps:

[0038] 9.3 mL ethyl orthosilicate was dissolved in a mixture of alcohol (100 mL) and deionized water (9.3 mL); to facilitate hydrolysis, nitric acid was added to adjust the pH of the solution to about 1 with stirring. After the solution turned clear, 0.07 g NaNO.sub.3, 0.24 g KNO.sub.3, 0.28 g Ca(NO.sub.3).sub.2.4H.sub.2O and 0.92 g of a HBO.sub.3 solution were added to the solution, stirred vigorously, and heated at 60° C. Then, ammonia water was added to adjust the pH to about 7 to form a gel. After drying the gel obtained, it was calcined at 700° C. for 2 h to obtain a silicon-based amorphous filler. Finally, 60% of ZrO.sub.2 (particle size is 5 μm) and 40% of the silicon-based amorphous filler were weighed, and were ground and mixed at the ball mill for 16 hours. After drying, the mixture was pressed into a sheet at 7 MPa and sintered at 850° C. to obtain the low temperature co-fired ceramic material.

[0039] The dielectric properties of the low temperature co-fired dielectric material prepared in this example are shown in FIG. 1. The dielectric constant was 11.11 at 1 MHz, the dielectric loss was 0.0006 at 1 MHz.

[0040] In order to examine the compatibility of the material with a silver electrode in co-firing, we used a 5% polyvinyl butyral (PVB) solution to granulate the powdered mixture of zirconia and glass after ball milling. The mixture was then dry pressed into a sheet at 7 MPa and the surface of the sheet was coated with the silver electrode. Finally, the sheet was sintered at 850° C. FIG. 2(a) is the SEM image of a cross section of the silver electrode and the green sheet after co-firing, and it could be seen that the silver electrode and the ceramic were tightly bonded without delamination or cracks. FIG. 2(b) shows that the silver content dropped sharply at the silver electrode/ceramic interface, indicating that no diffusion occurred during firing.

Example 4

[0041] An example of the preparation method of the low temperature co-fired dielectric material of the present invention includes the following steps:

[0042] 9.3 mL ethyl orthosilicate was dissolved in a mixture of alcohol (100 mL) and deionized water (9.3 mL); to facilitate hydrolysis, nitric acid was added to adjust the pH of the solution to about 1 with stirring. After the solution turned clear, 0.07 g NaNO.sub.3, 0.24 g KNO.sub.3, 0.28 g Ca(NO.sub.3).sub.2.4H.sub.2O and 0.92 g of a HBO.sub.3 solution were added to the solution, stirred vigorously, and heated at 60° C. Then, ammonia water was added to adjust the pH to about 7 to form a gel. After drying the gel obtained, it was calcined at 700° C. for 2 h to obtain a silicon-based amorphous filler. Finally, 65% of ZrO.sub.2 (particle size is 5 μm) and 35% of the silicon-based amorphous filler were weighed, and were ground and mixed at the ball mill for 15 hours. After drying, the mixture was pressed into a sheet at 7 MPa and sintered at 850° C. to obtain the low temperature co-fired ceramic material.

[0043] The dielectric properties of the low temperature co-fired dielectric material prepared in this example are shown in FIG. 1. The dielectric loss was 0.0004 at 1 MHz. The low temperature co-fired dielectric material described in this example was tightly bonded to a silver electrode after co-firing. No delamination, warpage, etc. occurred.

[0044] Hereinbefore described are only preferred examples of the present invention. It should be noted that any modification or improvement carried out by those skilled in the art within the spirit of the present invention should be regarded as within the scope of protection of the present invention.