Marlin Semiconductor Limited is an Irish patent holding company founded in 2020, formerly known as Sandyford Semiconductor Limited. It is a subsidiary of Longitude Licensing Limited, which is part of the IPValue Management patent monetization firm. IPValue, in turn, has been owned by private equity firm Vector Capital since 2014. Marlin Semiconductor is headquartered in Dublin, Ireland, and operates as a non-practicing entity (NPE).
As an NPE, Marlin Semiconductor Limited has no products or services of its own. The company's business is to acquire and assert patent portfolios. In June 2021, Marlin acquired a large portfolio of over 800 patents and applications from United Microelectronics Corporation (UMC), a major semiconductor foundry. The patents are broadly related to semiconductor fabrication processes, logic, memory, and packaging. The company monetizes this portfolio through licensing negotiations and litigation.
The company is an active patent plaintiff. In 2025, Marlin and its parent company, Longitude Licensing, began litigating the ex-UMC portfolio, filing patent infringement lawsuits against major technology companies including Apple, Broadcom, Qualcomm, Lenovo, and TSMC in the Western and Eastern Districts of Texas. The single defensive case listed in the provided database—a proceeding at the U.S. Patent and Trademark Office's Patent Trial and Appeal Board (PTAB)—is a direct result of this assertion campaign.
That notable PTAB case, Taiwan Semiconductor Mfg Co Ltd v. Marlin Semiconductor Ltd, is an inter partes review (IPR) petition filed by TSMC and Apple in April 2025 to challenge the validity of a Marlin-asserted patent. This defensive challenge followed Marlin's ITC complaint and district court lawsuits accusing the companies of infringing the ex-UMC patents through the manufacture and sale of semiconductor devices made with advanced process nodes.