Patent ID: 11872656
Assignee: SENJU METAL INDUSTRY CO., LTD.
Field: Surface technology, coating (Chemistry)
Classification: CPC B  C  H | IPC B  C  H

Claim 0:
1. A core material comprising:
a core having 0.95 to 1.0 sphericity;
a solder layer made of a (Sn-58Bi)-based solder alloy provided on an outer side of the core; and
a Sn layer provided on an outer side of the solder layer, wherein
when a concentration ratio of Bi contained in the solder layer is a concentration ratio=a measured value of Bi/a target Bi content, the concentration ratio is 91.4% to 108.6%, or
when the concentration ratio of Bi contained in the solder layer is a concentration ratio=an average value of measured values of Bi/a target Bi content, the concentration ratio is 91.4% to 108.6%,
a thickness of the solder layer on one side is 1 μm or more and 100 μm or less,
a thickness of the Sn layer is 0.1 μm to 12 μm on one side,
the thickness of the Sn layer is 0.215% or more and 36% or less of the thickness of the solder layer, and
the core material has a yellowness of 8.5 or less in a L*a*b* table color system, and when ten sample core materials produced in a same production batch as the core material having the yellowness of 8.5 or less are bonded to a substrate by reflow processing, none of the ten sample core materials exhibit a defect at a time of bonding.