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:
Jan. 11, 2000
Filed:
Aug. 25, 1997
Masami Sakuraba, Shiojiri, JP;
Masami Kimura, Shiojiri, JP;
Junji Nakamura, Shiojiri, JP;
Masaya Takahara, Shiojiri, JP;
Dowa Mining Co., Ltd., Tokyo, JP;
Abstract
A conductor pattern is formed on at least one surface of an AlN- or Si.sub.3 N.sub.4 -based ceramic substrate which is such that the ratio between the principal metal component binding with N to form the ceramic mass and the B in the BN remaining on the surface layer is no more than 50.times.10.sup.-6 as either B/Al or B/Si, wherein B/Al represents the ratio of I.sub.B to I.sub.Al where I.sub.B is the X-ray diffraction intensity of boron present on the surface layer and I.sub.Al is the X-ray diffraction intensity of aluminum, and B/Si represents the ratio of I.sub.B to I.sub.Si where I.sub.B is as defined above and I.sub.Si is the X-ray diffraction intensity of silicon. The thus produced circuit board has both a peel strength of at least 30 kg/mm.sup.2 and a capability of withstanding at least 30 heat cycles and, hence, satisfies the performance requirements of the recent models of power module ceramic circuit boards.