Principal Mechanical Engineer, Thermal Vacuum

Commonwealth Fusion Systems LLC; Milpitas, Northern (CA, KY); Hybrid; USD 150,000 - 225,000; Full time

Benefits offered by this job

Equity

Health, dental, and vision insurance

401(k) with employer matching

Flexible vacation days

Parental leave

Sick days

Team-building activities

Job summary

Commonwealth Fusion Systems LLC is seeking a Principal Mechanical Engineer to join our R&D and equipment design team to drive end-to-end design, integration, and implementation of advanced thermal vacuum equipment and R&D machinery.

You will lead system design, establish requirements, supervise design reviews, and mentor mechanical engineers while collaborating with scientists, vacuum specialists, and electrical engineers to deliver in-spec solutions.

Qualifications

• Master’s degree in Mechanical Engineering or related field.
• 15+ years of experience designing and implementing complex R&D systems or semiconductor equipment.
• Proven capability in high-temperature structural design and complex thermal management within vacuum environments.
• 3D modeling in SolidWorks and/or NX with experience in FEA/thermal simulation tools (COMSOL, ANSYS).
• Hands-on capability bridging design to shop floor (machining, prototyping, troubleshooting).
• Vendor management experience and ability to lead teams in direct and matrixed structures.

Responsibilities

• Lead design, integration, and validation of advanced R&D processing equipment.
• Define system-level requirements and innovative design concepts tied to mechanical precision.
• Standardize engineering workflows and best practices using semiconductor standards as a guide.
• Lead design reviews emphasizing manufacturability (DFx) and best practices for mechanical design.
• Collaborate with cross-functional teams including scientists, vacuum specialists, and electrical engineers.

Skills

Thermal expertise

Structural design

Leadership

Education

Master’s degree in Mechanical Engineering

Tools

SolidWorks

NX

COMSOL/ANSYS

Job description

Commonwealth Fusion Systems LLC is seeking a Principal Mechanical Engineer to join our R&D and equipment design team to drive end-to-end design, integration, and implementation of advanced thermal vacuum equipment and R&D machinery.

You will lead system design, establish requirements, supervise design reviews, and mentor mechanical engineers while collaborating with scientists, vacuum specialists, and electrical engineers to deliver in-spec solutions.