The National Samsung Electronics Union, the largest of the tech giant’s several unions with about 28,000 workers, announced the decision Wednesday after wage negotiations with management stalled. The two sides have been in discussions over pay increases since the start of this year but have failed to narrow their differences.

“What we want is not a 1-2% wage increase. What we want is to be paid fairly for the amount of work done,” the union said in a statement. “We want to be compensated for our labor fairly and transparently.”

The union’s decision comes as Samsung, led by executive chairman Jay Y. Lee, finds itself in the unusual position of playing catchup in a key sector of the chips industry. Local rival SK Hynix Inc has jumped out to an early lead in the memory chips that are used for the development of artificial intelligence services, a booming sector of the business.

Samsung shares fell as much as 1.7% after the strike was reported, taking its loss since the April peak to roughly 10%.

Son Woo-mok, head of the union, said that one of the key issues in negotiations is bonus payments. In March, Samsung’s labour-management council decided to increase this year’s pay by 5.1%.

South Korea has been working to contain inflation in recent months, like many other countries. Korea’s inflation slowed more than expected in April, with consumer prices rising 2.9%.

Unionised workers have drawn a public backlash after holding a concert-like rally with performances by celebrities in Seoul last week. Samsung Electronics has not had a strike since its founding in 1969.