Principal Mechanical Engineer - Vacuum

Commonwealth Fusion Systems

Milpitas (CA)

On-site

USD 180,000 - 280,000

Full time

45 hours ago

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Benefits offered by this job

Equity

Company holidays

Flexible vacation

Sick days

Parental leave

Health, dental, and vision insurance

401(k) with employer matching

Professional growth

Team-building

Job summary

Commonwealth Fusion Systems is seeking a Principal Mechanical Engineer to join our R&D and equipment design team to drive end-to-end hardware development for next-generation processing equipment. You will own the architecture, integration, and verification of high-performance systems in vacuum environments.

This role requires 15+ years in complex R&D or semiconductor equipment, mastery of thermal/structural design, vacuum systems, and hands-on capability to bridge design and shop floor.

Qualifications

Master's degree in Mechanical Engineering or related field.
15+ years of experience in design and implementation of complex R&D systems or semiconductor equipment.
Thermal and structural design expertise in vacuum environments.
Deep vacuum system understanding including outgassing, seals, and pump-down optimization.
Proficiency in 3D modeling (SolidWorks/NX) and FEA/thermal tools (COMSOL/ANSYS).
Hands-on capability bridging design and shop floor (machining/prototyping).
Vendor management experience with global suppliers.
Leadership across direct and matrix teams.

Responsibilities

Lead system design: drive design, integration, and validation of advanced R&D processing equipment.
Define requirements: establish system-level requirements and innovative design concepts.
Standardize best practices: implement engineering workflows using semiconductor standards.
Lead design reviews: conduct reviews emphasizing manufacturability (DFx).
Collaborate with cross-functional teams including scientists, vacuum specialists, and electrical engineers.
Report on project milestones and ensure on-time, in-spec delivery.
Mentor engineering staff on technical delivery and professional development.
Execute concepts through assembly, testing, and implementation.

Skills

Leadership

Team collaboration

Mentoring

Project management

Cross-functional

Education

Master's degree in Mechanical Engineering

Tools

SolidWorks

COMSOL

ANSYS

Job description

About Commonwealth Fusion Systems:

Commonwealth Fusion Systems is on a mission to deliver the urgent transition to fusion energy.

About Commonwealth Fusion Systems:

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. And we're working with policymakers, suppliers, and many others to build the energy industry of the future. We’re in the best position to make it happen. Since 2018, we’ve raised $4 billion of capital, making us the largest and leading fusion company in the world. Now we’re looking for more thinkers, doers, builders, and makers to join us. People who’ll bring new perspectives, solve tough problems, and thrive as part of a team. If that’s you and this role fits, we want to hear from you.

Join the power movement as a Principal Mechanical Engineer

We’re looking for a Principal Mechanical Engineer to join our R&D and equipment design team to help build the next generation equipment. You will be responsible for the end-to-end design, integration, and implementation of advanced thermal vacuum equipment and R&D machinery. This role requires you to be a technical expert who can drive innovative architecture while maintaining the procedural discipline necessary for high-performance hardware. If you enjoy solving complex thermal-mechanical problems in vacuum environments and mentoring others in a collaborative, fast-paced setting, this is your opportunity to make an impact.

What you'll do:

Lead System Design: Drive the design, integration, and validation of advanced R&D processing equipment
Define Requirements: Establish system-level requirements and innovative design concepts that directly correlate mechanical precision to product quality
Standardize Best Practices: Implement and maintain engineering workflows, and best practices using semiconductor standards as your guide
Lead Design Reviews: Conduct rigorous reviews for overall mechanical systems and sub-systems, emphasizing manufacturability (DFx) and best practices for mechanical design
Collaborate & Interface: Generate and maintain critical interfaces with cross-functional teams, including scientists, vacuum specialists, and electrical engineers
Project Accountability: Report on project milestones to stakeholders, ensuring delivery of on-time and in-spec outcomes
Mentor Talent: Coach engineering staff on technical delivery, procedural discipline, and professional development
Get Things Done: Act with speed to drive projects from concept through assembly, testing, and implementation

What we’re looking for:

Education: Master’s degree in Mechanical Engineering or a related field (or equivalent industrial experience)
Experience: 15+ years of experience in the design and implementation of complex R&D systems or semiconductor manufacturing equipment
Thermal & Structural Expertise: Proven capability in high-temperature structural design and complex thermal management within vacuum environments
Vacuum System Proficiency: Deep understanding of vacuum architecture, including material outgassing, seal integrity, and pump-down optimization
Software Mastery: Expertise in 3D modeling (SolidWorks and/or NX) and FEA/Thermal simulation tools (COMSOL, ANSYS)
Hands-on Capability: Ability to bridge the gap between design and the shop floor, including experience with manual/CNC machining, prototyping, and hardware troubleshooting
Vendor Management: Experience selecting and qualifying global vendors for specialized components or custom sub-systems
Leadership: Demonstrated ability to lead effectively in both direct and matrixed organizational structures

Bonus points for:

R2R Expertise: Experience designing or integrating roll-to-roll (R2R) systems for material processing
Semiconductor Background: Prior success building first-of-kind or experimental tools for semiconductor R&D or thin-film deposition
Standards Knowledge: Familiarity with SEMI, ASME, ASTM, and other industry-standard mechanical codes
Motion Control: Experience designing precision motion and motor-controlled systems within challenging environments

Must-have requirements:

Ability to lift up to 25 lbs occasionally
Perform activities such as stooping, climbing, standing, sitting for extended periods of time
Willingness to travel or work required nights/weekends/on-call occasionally
Dedication to safety to mitigate industrial hazards that may include heat, cold, noise, fumes, strong magnets, lead (Pb), high voltage, high current, pressure systems, and cryogenics

At CFS, we excel in fast-paced environments, driven by our values of integrity, execution, impact, and self-critique. As we grow, we’re eager to bring on mission-driven folks who offer diverse perspectives and fresh ways to tackle challenges.

We value diversity deeply and are proud to be an equal opportunity employer by choice. We consider all qualified applicants equally, regardless of race, color, national origin, ancestry, citizenship status, protected veteran status, religion, physical or mental disability, marital status, sex, sexual orientation, gender identity or expression, age, or any other basis protected by law.

This role requires compliance with U.S. laws concerning the export of controlled or protected technologies or information (collectively, “Export Control Laws"). Any offer of employment will be contingent on the need for compliance with such Export Control Laws.

Salary range for this full-time position + equity + benefits. The actual salary will depend on level, location, qualifications, and experience. The range displayed on each job posting reflects new hire salaries for the position across all US locations.

Benefits include: