Flex

Sr. Mechanical Development Engineer

Flex$105K — $144K *
Aerospace & Defense
5 - 7 years of experience
Job Overview by Ladders

Qualifications

  • BS/MS in Mechanical Engineering or equivalent experience.
  • 7+ years developing complex mechanical components or assemblies for electro mechanical systems; experience with liquid cooling or fluid systems strongly preferred.
  • Strong proficiency with CAD (SolidWorks, Creo, NX), drawing generation, and GD&T (ASME Y14.5).
  • Experience designing for precision machining, brazing, plating, elastomer sealing, and pressure rated components.
  • Hands-on experience with pressure/leak testing, dimensional inspection, materials evaluation, and mechanical validation testing.
  • Familiarity with materials (copper, aluminum, stainless steel, polymers, elastomers) and their behavior in liquid coolant environments.

Responsibilities

  • Own mechanical design for liquid cooling components including cold plates, manifolds, quick-disconnects, and chassis interfaces.
  • Create and manage detailed CAD models, drawings, GD&T, and tolerance stack-ups for manufacturable designs.
  • Select materials and finishes to ensure long-term durability in liquid cooling environments.
  • Perform engineering calculations related to mechanical stress, fatigue, and structural integrity.
  • Build and iterate on prototypes to assess fit, finish, assembly, and performance.
  • Collaborate with manufacturing engineering and suppliers on various processes like brazing and sealing.
  • Work with cross-disciplinary teams to translate product requirements into mechanical specifications.

Benefits

  • Full range of medical, dental, and vision plans
  • Life Insurance
  • Short-term and Long-term Disability
  • Matching 401(k) Contributions
  • Vacation and Paid Sick Time
  • Tuition Reimbursement
Full Job Description
Job Summary

Job Description

To support our extraordinary teams who build great products and contribute to our growth, we're looking to add a Mechanical Development engineer located in Littleton, MA.

Reporting to the Product Manager the Mechanical Development engineer The Sr. Mechanical Design Engineer will own the design, analysis, validation, and refinement of mechanical components and assemblies that enable reliable, high efficiency liquid cooling. They will work closely with Thermal, Electrical, Product Development, Manufacturing, and Quality teams to take products from concept through launch and into scalable production.

What a typical day looks like:

Mechanical Design & Development
  • Own mechanical design for liquid cooling components including cold plates, manifolds, quick-disconnects, tubing assemblies, housings, and chassis interfaces.
  • Create and manage detailed CAD models, 2D drawings, GD&T, and tolerance stack-ups to ensure robust, manufacturable designs.
  • Select materials and finishes to address corrosion, galvanic compatibility, cleanliness, pressure containment, and long-term durability in liquid cooling environments.
  • Drive sealing strategies using O-rings, gaskets, welds, brazes, and adhesives matched to coolant chemistry and operating conditions.

Engineering Analysis
  • Perform engineering calculations and simulations related to mechanical stress, thermal expansion, fatigue, vibration, flow/pressure, and structural integrity.
  • Collaborate with thermal engineers to optimize mechanical features influencing flow distribution, pressure drop, fin/channel geometry, and heat transfer efficiency.
  • Conduct DFM reviews with suppliers to align machining, brazing, and fabrication methods with design requirements.

Prototyping & Validation
  • Build and iterate on prototypes to evaluate fit, finish, assembly, and performance.
  • Develop mechanical validation plans for pressure tests, leak testing, burst testing, vibration/shock, environmental exposure, thermal cycling, and dimensional inspection.
  • Design test fixtures and support automated data collection where needed.
  • Lead root cause analysis for failures (e.g., leaks, deformation, material incompatibility) and implement corrective design changes.

Manufacturing & Supplier Engagement
  • Collaborate with manufacturing engineering and suppliers on fabrication, machining, brazing, plating, and sealing processes.
  • Define critical-to-quality (CTQ) characteristics and participate in supplier qualification.
  • Review and approve tooling, control plans, and inspection criteria for new mechanical parts.
  • Support build events (EVT/DVT/PVT) and ensure mechanical components meet functionality, quality, and reliability targets.

Cross-Functional Collaboration
  • Work with Program Management and Product Development to translate product requirements into mechanical specifications.
  • Partner with Thermal and Electrical teams to ensure system-level integration of cooling hardware with processors, boards, and rack infrastructure.
  • Provide input to serviceability, reliability, manufacturability, and cost trade-off discussions.
  • Support customer evaluations, pilot deployments, and field feedback analysis.


The experience we're looking to add to our team:
  • BS/MS in Mechanical Engineering or equivalent experience.
  • 7+ years developing complex mechanical components or assemblies for electro mechanical systems; experience with liquid cooling or fluid systems strongly preferred.
  • Strong proficiency with CAD (SolidWorks, Creo, NX), drawing generation, and GD&T (ASME Y14.5).
  • Experience designing for precision machining, brazing, plating, elastomer sealing, and pressure rated components.
  • Hands-on experience with pressure/leak testing, dimensional inspection, materials evaluation, and mechanical validation testing.
  • Familiarity with materials (copper, aluminum, stainless steel, polymers, elastomers) and their behavior in liquid coolant environments.
  • Strong fundamental technical expertise in mechanical design and structural evaluation.
  • Strong working knowledge of fluid dynamics and heat transfer principles.
  • Excellent communication skills and ability to lead technical decisions across teams.


BO18

What you'll receive for the great work you provide:
  • Full range of medical, dental, and vision plans
  • Life Insurance
  • Short-term and Long-term Disability
  • Matching 401(k) Contributions
  • Vacation and Paid Sick Time
  • Tuition Reimbursement


Application Deadline:

Applications for this job position will be accepted for at least five days following the job posting start date below and continuing until the end date below or until the position is filled. This posting may close sooner due to application volume.
Job Posting Start Date 06-22-2026 Job Posting End Date 09-25-2026
The base pay range for this position is provided below. The final base rate offered will be determined using job-related, non-discriminatory criteria, including but not limited to experience, qualifications, geographic location, education, external market data, and internal equity.
$105,000.00 USD - $144,400.00 USD Annual

Job Category
Design, Process & Technology Engineering

Is Sponsorship Available?
No

About Flex

Flex Ltd. is an American Singaporean-domiciled multinational electronics contract manufacturer. It is the third largest global electronics manufacturing services (EMS), original design manufacturer (ODM) company by revenue, behind only Pegatron for what concerns original equipment manufacturers. Flex has manufacturing operations in over 30 countries, totaling approximately 200,000 employees.
Learn more about Flex
Size
172,648 employees
Market Cap
$9.7 billion
Industry
Net Income
$421 million
Founded
2016
5 Year Trend
+1.8%
Revenue
$23.3 billion
NASDAQ

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