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. 06, 2004
Filed:
Dec. 23, 1999
Kozo Yamasaki, Gifu, JP;
Osamu Hisada, Aichi, JP;
Katsuhiko Hasegawa, Aichi, JP;
Naoki Kito, Aichi, JP;
Satoshi Hirano, Aichi, JP;
NGK Spark Plug Co., Ltd., Aichi, JP;
Abstract
A multilayer-wiring substrate having a via hole structure and method for fabricating the same. Referring to FIGS. ( ) and ( ), after a via-hole is formed by exposure and development in lithography or by laser-drilling, a bottom portion of the via-hole is subjected to resin-etching so as to expose a surface A of a lower conductor as shown in FIG. ( ). The exposed surface A of the lower conductor is chemically etched so that the conductor is undercut. As a result, undesired material B such as adhered residual resin shown in FIG. ( ) is completely removed. In etching the conductor at the bottom of the via hole , the lower conductor is preferably etched in an amount of 5-30% of the thickness of the lower conductor to form a depression or recess A at a via hole bottom C as shown in FIG. ( ), thereby reliably establishing electrical continuity between the lower conductor and the upper conductor by means of a via-hole conductor as shown in FIG. ( ).