BEIJING (Reuters) - China's chip assembly and testing firm JCET said on Monday it plans to buy an 80% stake in SanDisk China's Shanghai-based unit specialising in flash memory products for about $624 million via cash.

Western Digital Corporation, parent company of SanDisk China, has established a long-term cooperation partnership with JCET since 2003, the company said in a filing to Shanghai bourse.

SanDisk Semiconductor Shanghai will become a joint venture of JCET and Western Digital, it said, adding that it will hold a 80% stake in the JV.

(Reporting by Beijing newsroom, editing by Ed Osmond)