Hitachi, Ltd.

Naoto Saito

Hiroyuki Ohta

Hideo Miura

Koji Sasaki

Kunio Matsumoto

Hiromi Shimazu

Yohei Tanno

Ryozo Yoshino

Mari Uchida

In a solidification sensor for measuring a solidification state of a liquid with a high degree of accuracy in real time, and for making the sensor small-sized with a reduced power consumption, the solidification sensor comprises a liquid absorbing portion formed of a liquid absorbable material, a substrate coupled to the liquid absorbing portion and a strain sensor for measuring strain exerted to the substrate due to a volumetric change upon solidification of a liquid absorbed in the liquid absorbing portion.

Solidification sensor

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.

IC card and its manufacturing method

Growing community of inventors

Kasumigaura, Japan

Naoto Saito