Synopex posted an operating loss of 1.8 billion won and sales of 76.9 billion won in the third quarter, the company said.
Sales jumped 41% from a year ago and is its highest quarterly sales in six years, the firm said.
In 2015, Synopex turned its business to focus on flexible printed circuit board-based IT components and membrane filters.
The firm said investments into new facilities, increased research spending, the COVID-19 pandemic and intensifying competition contributed to the loss.
Synopex was expanding its e-PTFE membrane and melt-blown filter facilities.
The company also acquired a new factory in Vietnam during the quarter.
Synopex stressed that it secured more orders this year compared to a year ago.