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:
Apr. 29, 2003
Filed:
Sep. 16, 1999
Koji Sasaki, Ibaraki-ken, JP;
Naoto Saito, Ibaraki-ken, JP;
Hideo Miura, Koshigaya, JP;
Hiroyuki Ohta, Tsuchiura, JP;
Kunio Matsumoto, Koshigaya, JP;
Ryozo Yoshino, Hadano, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
An IC card has an IC chip and a circuit layer formed between layers of a base material that are adhered together by an adhesive. The IC card has a thickness of 0.25 to 0.76 mm and therefore the thickness of the IC chip needs to be about 0.2 mm, which requires grinding of the IC chip. In use, the IC card is subject to bending forces which apply a bending stress on the chip. In the process of grinding the IC chip, grinding flaws having sharp parts arise that reduce the bending strength of the chip. Also, during the dicing process of the wafer, chipping occurs that results in notches having sharp tip parts being formed in the chip. The grinding flaws that result from the grinding and the notches that result from the chipping are etched to remove their sharpness, which occurs at the tip part of the grinding flaw or the tip part of the notch. By rounding these sharp parts through the etching step, the bending strength of the IC chip increases and the durability of the IC card is ensured.