Sr. Staff Thermal Engineer

Lightmatter is leading the revolution in AI data center infrastructure, enabling the next giant leaps in human progress. The company invented the world’s first 3D-stacked photonics engine, Passage™, capable of connecting thousands to millions of processors at the speed of light in extreme-scale data centers for the most advanced AI and HPC workloads. Lightmatter raised $400 million in its Series D round, reaching a valuation of $4.4 billion. We will continue to accelerate the development of data center photonics and grow every department at Lightmatter! If you're passionate about tackling complex challenges, making an impact, and being an expert in your craft, join our team of brilliant scientists, engineers, and accomplished industry leaders. Lightmatter is (re)inventing the future of computing with light! We are seeking a Thermal Engineer with strong expertise in thermal analysis and deep knowledge of semiconductor packaging technologies to join our team. In this role, you will work on leading-edge packaging technologies to enable AI architectures that set new industry standards in compute power, performance, and efficiency. As a part of the package technology team, you will be responsible for leading thermal analysis required for product definitions, driving innovative thermal solutions, and conducting analysis and validation efforts to deliver package and system designs that meet product landing zones. Your work will contribute to advanced package and system designs that meet power dissipation, assembly, and reliability requirements while delivering system-level solutions for leading-edge products in data centers and high-end compute segments. Responsibilities: Perform thermal simulations to influence package and system design. Propose novel thermal solutions to enable the Lightmatter product portfolio by investigating relevant technologies and design concepts. Develop and validate thermal models for various packaging designs including modeling heat transfer, airflow, and thermal interactions within complex electronic assemblies. Collaborate with design engineers to optimize thermal management solutions, including heat sinks, thermal interfaces, and cooling systems. Use CFD results to guide design iterations and improve thermal performance Drive characterization and validation of thermal designs and electronic assemblies through lab-scale prototyping and/or initiating appropriate experiments with vendors. Summarize and communicate findings to key stakeholders across Lightmatter, suppliers, and customers as required. Develop analytical or semi-empirical models for quick-turn assessments of new product concepts. Develop and maintain CFD tools, templates, and best practices to streamline the simulation process and improve efficiency. Develop automation scripts using Python or MATLAB to improve modeling efficiency. Write reports and document methodologies. Required Qualifications: M.S. or Ph.D. in Mechanical Engineering, Material Science, Chemical Engineering or a related engineering field. 5 years of experience in package or system thermal analysis. Deep knowledge of thermal conduction and convective heat transfer concepts. Experience in designing, modeling, testing, sourcing, and deploying advanced thermal management technologies such as TECs, heat pipes, vapor chambers, thermal interface materials, phase change materials, as well as liquid and air cooling systems. Experience in performing steady-state and transient thermal analysis using ANSYS Icepak, ANSYS Fluent, and/or Flotherm. Experience in setting up and interpreting CFD simulations for complex geometries and boundary conditions. Working knowledge of lab-scale validation techniques. Preferred Qualifications: Knowledge of fluid dynamics and assembly process modeling of 2D/3D packaging technologies and exposure to the thermal challenges associated with these technologies. Experience in two-phase immersion cooling and single and two phase liquid flow Knowledge of thermal