However, ProMos is locked in a dispute with its largest shareholder, Germany's Infineon Technologies AG.
Meanwhile, another analyst said the new deal would have no impact on Powerchip as it is just the continuation of an existing partnership.
"This agreement will make no difference as historically Powerchip had to sell 50-percent of its production to Mitsubishi -- on paper at least," said Eldon Pei, a semiconductor analyst at Deutsche Bank in Taipei.
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