Method for producing dielectric ceramic, and dielectric ceramic

Patent metadata

Field	Value
Publication number	US-10696596-B2
Application number	US-201615750936-A
Country	US
Kind code	B2
Filing date	Dec 21, 2016
Priority date	Dec 28, 2015
Publication date	Jun 30, 2020
Grant date	Jun 30, 2020

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

The invention claimed is:

1. 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;
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; and
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.

2. The method for producing a dielectric ceramic according to claim 1 , comprising the step of calcining raw materials to 850° C. or lower to yield the low-temperature-sintering material.

3. The method for producing a dielectric ceramic according to claim 1 , wherein the firing is performed at 1000° C. or lower.

4. The method for producing a dielectric ceramic according to claim 1 , 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.

5. The method for producing a dielectric ceramic according to claim 1 , wherein the resultant dielectric ceramic is a ceramic substrate.

6. The method for producing a dielectric ceramic according to claim 1 , 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.

7. The method for producing a dielectric ceramic according to claim 1 , wherein in the step of preparing the mixed powder particles, the mixed powder particles comprise Ag.

Assignees

• Hitachi Metals Ltd

Inventors

• Nakajima Hirokazu

Classifications

• C04B2235/408

  Noble metals · CPC title

• C04B2237/66

  Forming laminates or joined articles showing high dimensional accuracy, e.g. indicated by the warpage · CPC title

• C04B2235/3481

  Alkaline earth metal alumino-silicates other than clay, e.g. cordierite, beryl, micas such as margarite, plagioclase feldspars such as anorthite, zeolites such as chabazite · CPC title

• C04B2235/6025

  Tape casting, e.g. with a doctor blade · CPC title

• C04B35/62685

  characterised by the order of addition of constituents or additives · CPC title