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Crackless soldering in micro pad Disclosure Number: IPCOM000216403D
Publication Date: 2012-Apr-04
Document File: 1 page(s) / 55K

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When the number of the electrode pad in the magnetic head and the packaging density of the pad increased, the micro crack may occur. Doping Indium(In) into conventional solder material (Sn, Ag3% and 0.5%Cu) achieves crackless soldering even with high packaging density of electrode pad(60um or less of pad width).

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Crackless soldering in micro pad

 With the conventional solder material, the solder solidification rapidly occurs at nearly 220 deg C, and the contraction stress of solder solidification occurs around the electrode pad at a stretch.

 In case of Indium doped solder, since the difference between liquidus and solidus temperature is bigger than conventional solder material, the duration time of solder solidification is longer than conventional solder material.

 The longer solidification time gradually releases the contraction stress to the other portion. And at last minutes of the solder solidification, the stress is smaller than conventional solder material. It affects to eliminate the micro crack around electrode pads.

 The effectiveness had confirmed with the 1-9% of Indium doping rate as follows.

Disclosed by Hitachi Corporation