Method for producing dielectric ceramic, and dielectric ceramic

Patent metadata

Field	Value
Publication number	US-2018222800-A1
Application number	US-201615750936-A
Country	US
Kind code	A1
Filing date	Dec 21, 2016
Priority date	Dec 28, 2015
Publication date	Aug 9, 2018
Grant date	—

Abstract

A method for producing a dielectric ceramic includes: shaping mixed powdery particles including a cordierite material (2MgO.2Al2O3.5SiO2) and a low-temperature-sintering material including Al, Si and Sr, the Si being partially vitrified; and firing the resultant shaped body. The method includes the step of wet-pulverizing the low-temperature-sintering material together with at least the cordierite material to prepare mixed powder particles having a median diameter D50 less than 1 μm; and, in a process until a time of the preparation of the mixed powder particles, the low-temperature-sintering material undergoes no step of wet-pulverizing only the low-temperature-sintering material, and drying the resultant pulverized material.

First claim

1 .- 12 . (canceled)

13 . A method for producing a dielectric ceramic, comprising: shaping mixed powdery particles comprising a cordierite material (2MgO.2Al 2 O 3 .5SiO 2 ) and a low-temperature-sintering material comprising Al, Si and Sr, the Si being partially vitrified; and firing the resultant shaped body;
wherein the method comprises the step of wet-pulverizing the low-temperature-sintering material together with at least the cordierite material to prepare mixed powder particles having a median diameter D50 less than 1 μm; and wherein, in a process until a time of the preparation of the mixed powder particles, the low-temperature-sintering material undergoes no step of wet-pulverizing only the low-temperature-sintering material and drying the resultant pulverized material.

14 . The method for producing a dielectric ceramic according to claim 13 , wherein the resultant dielectric ceramic comprises, as a main phase thereof, Sr anorthite (SrAl 2 Si 2 O 8 ) and further comprises cordierite and alumina (Al 2 O 3 ); and has a dielectric constant of 6.5 or less at a frequency of 15 GHz and a porosity of 0.8% or less.

15 . The method for producing a dielectric ceramic according to claim 13 , comprising the step of calcining raw materials to 850° C. or lower to yield the low-temperature-sintering material.

16 . The method for producing a dielectric ceramic according to claim 13 , wherein the firing is performed at 1000° C. or lower.

17 . The method for producing a dielectric ceramic according to claim 13 , wherein a slurry of the mixed powder particles yielded by the wet-pulverization, the slurry comprising an organic solvent, is sheet-shaped into ceramic green sheets; and the ceramic green sheets are laminated onto each other to yield the shaped body.

18 . The method for producing a dielectric ceramic according to claim 13 , wherein the resultant dielectric ceramic is a ceramic substrate.

19 . The method for producing a dielectric ceramic according to claim 13 , wherein before the step of preparing the mixed powder particles, the cordierite material is pulverized to have a particle diameter D95 of 0.5 to 3.0 μm.

20 . The method for producing a dielectric ceramic according to claim 13 , wherein in the step of preparing the mixed powder particles, the mixed powder particles comprise Ag.

21 . A dielectric ceramic, comprising, as a main phase thereof, Sr anorthite (SrAl 2 Si 2 O 8 ) and further comprising cordierite (2MgO.2Al 2 O 3 .5SiO 2 ) and alumina (Al 2 O 3 ); and having a dielectric constant of 6.5 or less at a frequency of 15 GHz, and a porosity of 0.8% or less.

22 . The dielectric ceramic according to claim 21 , having an fQ product of 9 THz or more at a frequency of 15 GHz.

23 . The dielectric ceramic according to claim 21 , about which a variation in the shrinkage factor (%) of the ceramic is in a range of ±0.15% as a standard deviation 3σ when raw materials of the ceramic are fired.

24 . The dielectric ceramic according to claim 21 , comprising Ag in a proportion of 0.5 to 5% by mass, the proportion being in terms of the proportion of Ag in the composition of raw materials of the ceramic.

Assignees

• Hitachi Metals Ltd

Inventors

• Nakajima Hirokazu

Classifications

• C04B2235/5409

  expressed by specific surface values · CPC title

• C04B2235/5436

  micrometer sized, i.e. from 1 to 100 micron · CPC title

• B32B18/00

  Layered products essentially comprising ceramics, e.g. refractory products · CPC title

• C04B2237/341

  Silica or silicates · CPC title

• C04B35/62695

  Granulation or pelletising (devices for shaping artificial aggregates from ceramic mixtures B28B1/004) · CPC title