Principal Mechanical Engineer

Responsibilities

• Lead the end-to-end design, integration, and validation of advanced R&D equipment for thin-film processing
• Establish system-level requirements and innovative design concepts to ensure mechanical precision
• Implement and maintain engineering workflows and best practices using semiconductor standards
• Conduct rigorous design reviews emphasizing manufacturability (DFx) and mechanical best practices
• Collaborate with cross-functional teams including scientists, vacuum specialists, and electrical engineers
• Mentor engineering staff on technical delivery, procedural discipline, and professional development
• Drive projects from concept through assembly, testing, and implementation with speed and accountability

Requirements

• Master's degree in Mechanical Engineering or a related field (or equivalent industrial experience)
• 15+ years of experience in the design and implementation of complex R&D systems or semiconductor manufacturing equipment
• Proven expertise in high-temperature structural design and complex thermal management within vacuum environments
• Deep understanding of vacuum architecture, including material outgassing, seal integrity, and pump-down optimization
• Mastery of 3D modeling software (SolidWorks and/or NX) and FEA/Thermal simulation tools (COMSOL, ANSYS)
• Hands-on experience with manual/CNC machining, prototyping, and hardware troubleshooting
• Experience selecting and qualifying global vendors for specialized components or custom sub-systems
• Ability to lift up to 50 lbs and work in environments involving heat, noise, high voltage, or cryogenics

Preferred Qualifications

• Experience designing or integrating roll-to-roll (R2R) systems for material processing
• Success building first-of-kind or experimental tools for semiconductor R&D or thin-film deposition
• Familiarity with SEMI, ASME, ASTM, and other industry-standard mechanical codes
• Experience designing precision motion and motor-controlled systems within challenging environments

Benefits

• Competitive compensation with equity
• 13 Company-wide Holidays and flexible vacation days
• 10 sick days and a generous parental leave policy
• Health, dental, and vision insurance
• 401(k) with employer matching
• Professional growth opportunities and team-building activities

About the Company

Commonwealth Fusion Systems is on a mission to deliver the urgent transition to fusion energy. Combining decades of research, top talent, and new technologies, we’re designing and building commercially viable fusion power plants. Since 2018, we’ve raised nearly $3 billion in capital, making us the largest and leading private fusion company in the world.