Sr. Staff Thermal Design Engineer

d-Matrix; Santa Clara (CA); On-site; USD 140,000 - 210,000; Full time

Job summary

d-Matrix is seeking an experienced Thermal Engineer to lead end-to-end thermal design for AI XPU platforms. You will own liquid- and air-cooled systems, from cold plates to CDUs, ensuring reliable performance in data-center racks.

The role requires 7+ years in thermal design, CFD, and hardware testing, with hands-on experience in cooling hardware and lab instrumentation. You will partner across mechanical, electrical, packaging, and reliability teams to bring production-ready AI servers to

Qualifications

• Bachelors/Master/PhD in Mechanical/Thermal disciplines.
• 7+ years in thermal design, CFD, and physical testing of electronic systems.
• Experience with cold plates, rack manifolds, tubing, UQDs, and CDUs.
• Strong knowledge of flow networks, pressure drop, and hydraulic balancing.
• Familiarity with CFD tools (Simcenter Flotherm, Ansys) and lab instrumentation.
• Hands-on performance characterization of liquid-cooled hardware.

Responsibilities

• Lead thermal-fluid design of liquid cooling hardware for high-TDP XPUs.
• Define and select CDU infrastructure and tubing networks.
• Perform CFD and 1D hydraulic analyses to balance flow and minimize pressure drop.
• Evaluate materials, corrosion inhibitors, and long-term reliability of cooling circuits.
• Design air-cooled solutions including heatsinks, fans, and ducting.
• Develop 3D CFD models and 1D hydraulic simulations to predict temps and pressure.
• Set up thermal lab setups and run performance tests under varied workloads.
• Collaborate with Mechanical, Electrical, Packaging, and Reliability teams.

Skills

CFD modeling

Thermal design

Liquid cooling

Flow network analysis

Lab instrumentation

Thermal testing

1D hydraulic networks

Education

Bachelor’s in Mechanical Engineering

Master’s or Ph.D. in Mechanical/Thermal Engineering

Tools

Simcenter Flotherm

Flotherm XT

Ansys Icepak

Ansys Fluent

Flowmaster

Flownex

Job description

At d-Matrix, we are focused on unleashing the potential of generative AI to power the transformation of technology. We are at the forefront of software and hardware innovation, pushing the boundaries of what is possible. Our culture is one of respect and collaboration.

We value humility and believe in direct communication. Our team is inclusive, and our differing perspectives allow for better solutions. We are seeking individuals passionate about tackling challenges and are driven by execution. Ready to come find your playground? Together, we can help shape the endless possibilities of AI.

Role Overview

We are seeking an experienced Thermal Engineer to lead the end-to-end thermal design, architecture, and validation of our next-generation AI XPU computing platforms. Our roadmap spans silicon-level thermal management, server-level chassis engineering, and full 100kW+ liquid-cooled rack deployments. You will own the thermal-fluid design of our air-cooled and liquid-cooled systems, including cold plates, rack manifolds, tubing, and Coolant Distribution Units (CDUs), ensuring balanced flow, low pressure drop, and high reliability. You will partner with Mechanical, Electrical, Packaging, and Reliability teams to bring production-ready AI servers and racks to market.

What You Will Do

• 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 (thermocouples, RTDs, pressure transducers, flow meters, 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 You Will Bring

• 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 in 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.

Preferred Qualifications

• 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).

Equal Opportunity Employment Policy

d-Matrix is proud to be an equal opportunity workplace and affirmative action employer. We’re committed to fostering an inclusive environment where everyone feels welcomed and empowered to do their best work. We hire the best talent for our teams, regardless of race, religion, color, age, disability, sex, gender identity, sexual orientation, ancestry, genetic information, marital status, national origin, political affiliation, or veteran status. Our focus is on hiring teammates with humble expertise, kindness, dedication and a willingness to embrace challenges and learn together every day.