Senju Metal Industry Co., Ltd.

Tomoaki Nishino

Isamu Sato

Hiroyoshi Kawasaki

Takahiro Roppongi

Daisuke Soma

Yuji Kawamata

Takahiro Hattori

Shigeki Kondo

The present invention accurately distinguishes a soldering material less likely to oxidize. A Cu core ball has a Cu ball having a predetermined size, and a solder layer coating the Cu ball. The Cu ball provides a space between a semiconductor package and a printed circuit board. The Cu core ball has the soldering material having lightness greater than or equal to 62.5 in L*a*b* color space subsequent to a heating storage test performed for 72 hours in a temperature-controlled bath at 150&#xb0; C. with a temperature of 25&#xb0; C. and 40% humidity, and the soldering material, prior to the heating storage test, having lightness greater than or equal to 65 in the L*a*b* color space and yellowness less than or equal to 7.0 in the L*a*b* color space.

Soldering material

A core material including a core and a solder plating layer of a (Sn&#x2014;Bi)-based solder alloy made of Sn and Bi on a surface of the core. Bi in the solder plating layer is distributed in the solder plating layer at a concentration ratio in a predetermined range of, for example, 91.7% to 106.7%. Bi in the solder plating layer is homogeneous, and thus, a Bi concentration ratio is in a predetermined range over the entire solder plating layer including an inner circumference side and an outer circumference side in the solder plating layer.

Core material, semiconductor package, and forming method of bump electrode

Growing community of inventors

Tokyo, Japan

Tomoaki Nishino