Mechanical Design Engineer

Lightmatter is leading the revolution in AI data center infrastructure, enabling the next giant leaps in human progress. The company invented the world’s first 3D-stacked photonics engine, Passage™, capable of connecting thousands to millions of processors at the speed of light in extreme-scale data centers for the most advanced AI and HPC workloads.

Lightmatter raised $400 million in its Series D round, reaching a valuation of $4.4 billion. We will continue to accelerate the development of data center photonics and grow every department at Lightmatter!

If you're passionate about tackling complex challenges, making an impact, and being an expert in your craft, join our team of brilliant scientists, engineers, and accomplished industry leaders.

Lightmatter is (re)inventing the future of computing with light!

In this role, you will be working on leading-edge packaging technologies to enable AI architectures that set new industry standards for compute power, performance, and efficiency. As a member of the Packaging team, you will collaborate with several teams to identify key failure modes under product use conditions and run appropriate parametric design studies to influence product and package design upstream. You will be responsible for the package stack-up analysis, co-optimizing mechanical, optical and thermal aspects that influence package form factors, and driving socket/enabling mechanisms. You will utilize Geometric Dimensioning and Tolerancing (GD&T) to propose solutions that finalize the design. Your work will result in advanced package designs that meet power dissipation, assembly, optical, and reliability requirements, while delivering a system level solution for leading edge products in the data centers and high-end compute segment.

Responsibilities:

Create CAD models of package stack-up and associated components.

Perform mechanical design analysis to identify and implement solutions that improve package mechanical integrity.

Execute tolerance stack-up analyses and create GD&T drawings for advanced packages — including optically aligned assemblies where micron-level precision defines product performance

Apply manufacturing expertise to influence design choices, perform FMEAs, and evaluate the cost implications of process and design decisions.

Collaborate with package and systems teams to ensure packaging solutions comply with system boundary conditions.

Requirements:

BS or MS in Mechanical Engineering or a related field.

Minimum of 3 years of mechanical design experience in semiconductor packaging, optoelectronics, or photonics modules.

Proficiency in CAD tools such as Solidworks or Creo, with a focus on mechanical design best practices.

Expertise in Geometric Dimensioning and Tolerancing (GD&T) and tolerance stack-up analysis.

Manage prototype builds with external vendors, validating the designs, and ensuring the scalability to high volume manufacturability.

Working knowledge of semiconductor packaging technologies, including the mechanical and thermal trade-offs of 3D, 2.5D, and FCBGA architectures.

Preferred Qualifications

Knowledge of ASME Y14.5 standards.

Ability to drive results independently and with minimal supervision.

Working knowledge of FEA tools (ANSYS, Abaqus, or similar) for structural and thermal analysis.

Fiber array unit (FAU) attach, optical connector, or photonic alignment experience.

Experience with liquid cooling or advanced thermal architectures for AI/HPC systems.

Exposure to high-volume manufacturing and OSAT engagement in Asia.

Strong cross-functional communication skills and a bias toward fast, data-driven iteration.

We offer competitive compensation. The base salary range for this role determined based on location, experience, educational background, and market data.

Salary Range: total compensation goes beyond base salary, it also includes a new hire equity grant, annual performance-based equity, and other rewards that recognize your impact and contribution.

$135,000 — $212,000 USD

Benefits

Comprehensive Health Care Plan (Medical, Dental & Vision)

Retirement Savings Matching Program

Life Insurance (Basic, Voluntary & AD&D)

Generous Time Off (Vacation, Sick & Public Holidays)

Paid Family Leave

Short Term & Long Term Disability

Training & Development

Commuter Benefits

Flexible, hybrid workplace model

Equity grants (applicable to full-time employees)

Benefits eligibility may vary depending on your employment status and location. Lightmatter recruits, employs, trains, compensates, and promotes regardless of race, religion, color, national origin, sex, disability, age, veteran status, and other protected status as required by applicable law.

Export Control

Candidates should have capacity to comply with the federally mandated requirements of U.S. export control laws.