Among other things Key Foundry specialises in automotive ICs of which there is a massive world shortage with soaring prices.
Last February MagnaChip started running wafers on it 0.18 micron third generation BCD process which is optimised for auto chips.
Last September, MagnaChip sold its mixed signal foundry business and Fab 4 to a Korean private equity company called Magnus Semiconductor for $350 million.
Magnus is owned by Alchemist Capital Partners and Credian Partners, both based in Korea.
Hynix previously invested $180 million in Magnus.
Key Foundry has capacity of 82,000 8-inch wpm and Hynix has said it wants to increase its foundry business.