Samsung Electronics’ largest labour union said it would proceed with a planned 18-day strike beginning on May 21, after negotiations with management over pay and bonuses collapsed, raising the prospect of disruption at one of the world’s most important chipmakers.

The union and the company have clashed over performance bonuses at a time when Samsung’s memory-chip division is reporting record earnings, driven by surging demand for the high-bandwidth memory used in artificial-intelligence systems.

The union is demanding that Samsung scrap its current cap on performance bonuses, allocate 15% of operating profit to such payments and write the commitment into employees’ contracts.

Two rounds of government-mediated talks were held on May 11 and 12 under the Ministry of Employment and Labor. The final session ran for about 17 hours before ending without agreement in the early hours of the following day.

The union said around 41,000 members had indicated a willingness to take part in the action, and South Korean media estimated total participation could exceed 50,000 workers. Local outlets put potential losses to the company at up to 40 trillion won.

A walkout of that scale would threaten output of advanced memory chips at a moment of intense global demand. The prospect of disruption prompted South Korea’s prime minister to convene an emergency meeting as the strike date approached.