Principal Mechanical Engineer, Vacuum Systems & R&D

Commonwealth Fusion Systems LLC; Milpitas (CA); On-site; USD 150,000 - 225,000; Full time

Benefits offered by this job

Equity

13 Company-wide Holidays

Flexible vacation days

10 sick days

Parental leave policy

Health, dental, and vision insurance

401(k) with employer matching

Professional growth opportunities

Team-building activities

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 design, integration, and implementation of advanced thermal vacuum equipment and R&D machinery.

This role demands technical leadership, innovative architectures, and mentoring others in a fast-paced setting, solving complex vacuum-based thermal-mechanical problems with impact across projects.

Qualifications

• Master’s degree in Mechanical Engineering or related field.
• 15+ years in design and implementation of complex R&D systems or semiconductor equipment.
• Thermal and structural design experience in vacuum environments.
• Deep understanding of vacuum architecture, outgassing, seals and pump-down.
• Proficiency in 3D CAD and FEA/thermal simulation tools.
• Hands-on experience bridging design and shop floor activities.
• Vendor management with global suppliers.
• Strong leadership in direct and matrixed teams.

Responsibilities

• Lead system design of advanced R&D processing equipment.
• Define system-level requirements linked to mechanical precision.
• Standardize engineering workflows using semiconductor standards.
• Lead design reviews focusing on manufacturability (DFx).
• Collaborate with scientists, vacuum specialists and electrical engineers.
• Report milestones to stakeholders ensuring on-time, in-spec delivery.
• Mentor engineers on technical delivery and safety.
• Drive projects from concept through assembly and testing.

Skills

Thermal design

Vacuum systems

3D CAD (SolidWorks/NX)

FEA/thermal simulations

Machining & prototyping

Vendor management

Leadership

DFx

Motion control

Education

Master's degree in Mechanical Engineering

Tools

SolidWorks

NX

COMSOL

ANSYS

Job description

Commonwealth Fusion Systems 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.

This role demands technical leadership, innovative architectures, and mentoring others in a fast-paced setting, solving complex vacuum-based thermal-mechanical problems with impact across projects.