| CPC B23K 35/264 (2013.01) [B23K 35/025 (2013.01); B23K 35/362 (2013.01); B23K 2101/42 (2018.08); B23K 2103/08 (2018.08)] | 23 Claims |
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1. A solder paste comprising:
a solder alloy comprising:
from 40 to 65 wt. % bismuth;
from 1 to 10 wt. % indium;
at least one of:
from 0.1 to 5 wt. % gallium,
from 0.1 to 5 wt. % zinc,
from 0.1 to 2 w. % copper,
from 0.01 to 0.1 wt. % cobalt,
from 0.1 to 2 wt. % silver,
from 0.005 to 0.05 wt. % titanium, and
from 0.01 to 1 wt. % nickel;
optionally one or more of:
up to 1 wt. % vanadium,
up to 1 wt. % rare earth metals,
up to 1 wt. % neodymium,
up to 1 wt. % chromium,
up to 1 wt. % iron,
up to 1 wt. % aluminium,
up to 1 wt. % phosphorus,
up to 1 wt. % gold,
up to 1 wt. % tellurium,
up to 1 wt. % selenium,
up to 1 wt. % calcium,
up to 1 wt. % vanadium,
up to 1 wt. % molybdenum,
up to 1 wt. % platinum,
up to 1 wt. % magnesium,
up to 1 wt. % silicon, and
up to 1 wt. % manganese; and
the balance tin together with any unavoidable impurities; and
a solder flux;
wherein the solder flux comprises an activator;
wherein the activator comprises an organic acid activator and an organic amine activator, and the molar ratio of organic acid activator to organic amino activator is from 0.8 to 2.5; and
wherein the activator comprises:
from 1 to 5 wt. % glutaric acid,
from 5 to 12 wt. % adipic acid,
from 0 to 2 wt. % 2-iodobenzoic acid, and
from 2 to 10 wt. % 2-ethylimidazole.
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