The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 14, 1999
Filed:
Mar. 25, 1997
Yuji Katsuda, Nagoya, JP;
Yukimasa Mori, Nagoya, JP;
Michio Takahashi, Nagoya, JP;
Yuki Bessho, San Jose, CA (US);
NGK Insulators, Ltd., , JP;
Abstract
In AlN crystal grains constituting a sintered body, is contained: 150 ppm-0.5 wt. %, preferably at most 0.1 wt.%, of at least one rare earth element (as oxide thereof); at most 900 ppm, preferably at most 500 ppm of at least one metal impurity except rare earth elements; and preferably at least 0.5 wt. % of oxygen measured by an electron probe X-ray microanalyzer. The grains have an average grain diameter of preferably at least 3.0 .mu.m and show a main peak in the wavelength range of 350-370 nm of spectrum obtained by a cathode luminescence method. The sintered body composed of AlN crystal grains has a volume resistivity at room temperature of at most 1.0.times.10.sup.12 .OMEGA..multidot.cm.