Mechanical Design Engineer

Job Title

Mechanical Design Engineer

Role Summary

As a Mechanical Design Engineer on the Packaging team, you will develop mechanical package and socket designs for photonics-based AI compute modules. You will perform stack-up, tolerance, thermal and structural analyses and deliver manufacturable designs that meet optical, thermal, and reliability requirements.

You will collaborate cross-functionally with package, systems, and vendor teams to move designs from prototype to high-volume manufacturability for data center and high-performance computing products.

Experience Level

Mid-level — typically requires a minimum of 3 years of relevant mechanical design experience in semiconductor packaging, optoelectronics, or photonics modules.

Responsibilities

Key responsibilities include:

• Create CAD models of package stack-ups and related components.
• Perform mechanical design and tolerance stack-up analyses; produce GD&T drawings for micron-level optical alignment assemblies.
• Co-optimize mechanical, optical, and thermal aspects of package form-factor and socket/enabling mechanisms.
• Run FMEAs and evaluate manufacturability and cost implications of design choices.
• Manage prototype builds with external vendors and validate designs for scalability to high-volume manufacturing.
• Collaborate with package and systems teams to ensure solutions meet system boundary conditions and reliability targets.

Requirements

Must-have technical skills and experience:

• Minimum 3 years mechanical design experience in semiconductor packaging, optoelectronics, or photonics modules.
• Proficiency with CAD tools (SolidWorks or Creo) and mechanical design best practices.
• Expertise in Geometric Dimensioning & Tolerancing (GD&T) and tolerance stack-up analysis.
• Working knowledge of semiconductor packaging technologies and mechanical/thermal trade-offs for 3D, 2.5D, and FCBGA architectures.
• Experience managing prototype builds with vendors and driving designs toward high-volume manufacturability.
• Ability to perform FMEAs and assess cost/manufacturing implications of design decisions.
• Must be able to comply with U.S. export control laws.

Nice-to-have:

• Familiarity with ASME Y14.5 standards.
• Experience with FEA tools (ANSYS, Abaqus) for structural and thermal analysis.
• Experience with fiber array unit attach, optical connector alignment, or photonic assembly.
• Experience with liquid cooling or advanced thermal architectures for AI/HPC systems and OSAT engagement in Asia.

Education Requirements

Bachelor's or Master's degree in Mechanical Engineering or a related field.

Compensation: base salary range $135,000—$212,000 USD; total compensation may include equity and performance-based components. Benefits include medical, dental, vision, retirement matching, paid leave, disability coverage, commuter benefits, and a flexible hybrid workplace model.

About the Company

Company: Lightmatter

Headquarters: Boston, Massachusetts, USA

Lightmatter develops photonic AI data-center infrastructure and optical chips for extreme-scale AI and HPC. The company invented the Passage 3D‑stacked photonics engine to provide high-bandwidth, low-latency interconnects across large-scale processors and raised $400M in Series D financing at a reported $4.4B valuation.