Sr. Staff Thermal Design Engineer

d-Matrix • Santa Clara, CA

3d • $175,000 - $265,000

About The Position

d-Matrix is seeking an experienced Thermal Engineer to lead end-to-end thermal design, architecture, and validation for next-generation AI XPU computing platforms. The roadmap spans silicon-level thermal management, server-level chassis engineering, and liquid-cooled rack deployments exceeding 100 kW. The role owns thermal-fluid design for air-cooled and liquid-cooled systems, including cold plates, rack manifolds, tubing, and Coolant Distribution Units (CDUs), with a focus on balanced flow, low pressure drop, and reliability. The engineer partners with Mechanical, Electrical, Packaging, and Reliability teams to bring production-ready AI servers and racks to market.

The work includes developing liquid-cooling hardware and infrastructure, analyzing flow networks, evaluating fluid and material compatibility, designing air-cooled solutions, modeling performance with CFD and hydraulic simulations, and conducting laboratory testing under varied workloads and ambient conditions.

Requirements

• Bachelor’s, Master’s, or Ph.D. in Mechanical Engineering, Thermal Engineering, Aerospace Engineering, or a related discipline.
• 7+ years of hands-on experience in thermal design, CFD modeling, and physical testing of air-cooled and liquid-cooled electronic systems.
• Demonstrated expertise in designing, selecting, and qualifying cold plates, rack manifolds, fluid tubing, UQDs, and CDUs.
• Deep understanding of flow networks, pressure-drop calculations, hydraulic balancing, and fluid distribution across multi-socket, multi-tray server racks.
• Knowledge of air-cooled thermal management, including fan selection, heat-sink design, and system impedance testing.
• Experience with CFD tools such as Simcenter Flotherm, Flotherm XT, Ansys Icepak, or Ansys Fluent.
• Knowledge of lab instrumentation, including multi-channel DAQs (e.g., Keysight, Graphtec), thermal test vehicles (TTVs), flow benches, pressure calibration, and helium/pressure leak testing.
• Proven experience performing hands-on performance characterization and stress testing of liquid-cooled hardware.

Nice To Haves

• Experience with 1D hydraulic network simulation tools such as Flownex or Flowmaster.
• Proficiency with 3D mechanical CAD tools (e.g., PTC Creo, SolidWorks, Siemens NX) for component modeling and packaging integration.
• Familiarity with Open Compute Project (OCP) liquid-cooling standards and industry reliability metrics.
• Knowledge of thermal interface materials (TIM1, TIM1.5, phase-change materials) and advanced packaging thermal constraints (HBM, interposers, multi-die modules).

Responsibilities

• Lead thermal-fluid design and development of liquid-cooling hardware, including high-TDP XPU cold plates, rack manifolds, quick disconnects (UQDs), and tubing networks.
• Define and select liquid-cooling infrastructure, including internal and external CDUs.
• Perform fluid dynamics and flow-network analysis to balance flow, minimize pressure drop, and prevent flow starvation across multi-chassis racks.
• Evaluate fluid compatibility, materials, corrosion inhibitors, and long-term reliability of closed-loop cooling circuits.
• Design and optimize air-cooled thermal solutions, including heat sinks, fans, ducting, chassis airflow, and VRM/memory cooling.
• Build 3D CFD models and 1D hydraulic network simulations to predict junction temperatures, thermal resistance, fluid temperatures, and rack-level pressure drop.
• Architect thermal/fluid lab setups; instrument test vehicles and chassis with thermocouples, RTDs, pressure transducers, flow meters, and multi-channel DAQ; and execute performance testing of cold plates, manifolds, CDUs, and server/rack systems under varied workloads and ambient conditions.
• Partner with Mechanical, Electrical, Packaging, and Reliability teams to integrate thermal components into production-ready AI servers and racks.

What This Job Offers

• Job Type: Full-time
• Career Level: Senior