PrincipleThermalMechanicalEngineer

Job Posting Start Date 06-08-2026 Job Posting End Date 08-28-2026 At JetCool, a Flex company, we’re at the forefront of liquid cooling innovation, delivering advanced solutions that empower our partners in AI and high-performance computing. United by a shared purpose, our teams are pushing the limits of what’s possible and tackling complex challenges. A career at JetCool offers the opportunity to make a real impact by helping build smarter, more sustainable data centers. Together, we’re not just advancing technology — we’re redefining cooling standards to create a more sustainable tomorrow. ## Job Summary To support our extraordinary teams who build great products and contribute to our growth, we’re looking to add a **Principle Thermal Mechanical Engineer** located in**Littleton, MA.** Reporting to the**Product Manager** the **Principle Thermal Mechanical Engineer** will play a pivotal role in the early phases of product development and serving in a guidance capacity through product maturation. Our products drive sustainability across the data center infrastructure by allowing higher coolant temperatures and by driving more complete heat capture for liquid cooling. The Principal Mechanical Engineer will provide technical leadership, mentorship, and hands-on expertise in mechanical design, fluid dynamics, and heat transfer but also work closely with customers in communicating the art of the possible with JetCool technology and building a strong customer relationship on a technical level. **What a typical day looks like:** * Lead the initial design, analysis, and optimization of complex fluid systems from concept initial CAD to final detailed CAD and drawing for liquid cooling, including cold plates, pumps, fluids, tubing, and heat exchangers, for the latest computer processing chipsets. * Collaborate with customer and partner teams to integrate fluid systems into overall product designs. * Conduct fluid flow simulations, analyses, and tests to ensure efficient and re