Thermo-Mechanical Engineer

PH-005 | Founding Technical Staff | Boston, MA | Onsite | $150K – $220K base + equity

About Prahelika

Prahelika is building the domestic integration layer: 3D systems in which III-V semiconductors, state-of-the-art silicon, and novel interposers are stacked into one device, each doing what it does best. We co-design the signal path, the power tier, the thermal path, and the manufacturing process, so dies from any foundry become a system that silicon alone cannot deliver. Our first 3D systems serve defense radar and low-Earth-orbit satellite communications; the same platform extends to power electronics, data-center compute, and photonics. Backed by top-tier investors and built by engineers who demonstrated every tier of the stack as measured hardware before the company existed, Prahelika owns the layer between the transistor and the machine. Ultimate electronics through integration.

The role

Whoever owns a design here sees it through fabrication, packaging, measurement, shipping, and the next revision. Our 3D systems stack dissimilar semiconductors and substrates into one package, and in that stack heat and stress decide whether the electrical performance exists at all. The materials expand at different rates, bond at different temperatures, and conduct heat at rates orders of magnitude apart. One of our four founding axioms is that integration is driven by the package: thermal design and reliability are the launch pad for every program, so every program begins with heat and lifetime, not the schematic. The thermal and mechanical budget is set before the circuit is, and everyone else designs inside it.

You will own that budget. As our first thermo-mechanical engineer, you set the junction-to-package targets, choose the heat path across every interface, and predict warpage and fatigue before we spend a tape-out discovering them. We qualify on the customers with the hardest reliability bar in electronics, so the data you generate exists before the next customer asks for it. You will work directly with the RF, electromagnetics, and integration engineers and the founders, and the flows you build become part of the design kit the company runs on.

Required qualifications

• Ph.D. with 2+ years, or M.S. with 5+ years, in Mechanical Engineering, Electrical Engineering, Materials Science, or a related field, doing thermal and mechanical design for electronics or RF hardware that was built, tested, and delivered (industry, national lab, or postdoc). Equivalent practical experience may substitute for the degree requirement.

• Fluency in thermal and structural FEA (ANSYS Mechanical, Icepak, COMSOL, or equivalent) and a mechanical CAD system (NX, SolidWorks, Creo, or equivalent).

• Hands-on experience in at least two of the following:

  • Designing test vehicles on silicon, glass, or package substrates with integrated electrical structures for in-situ thermal measurement, using microfabrication techniques.

  • Cooling solutions built on advanced heat spreaders (diamond, SiC, CNT, liquid metal) or embedded, microfluidic, or two-phase cooling.

  • Validating and qualifying designs after fabrication and packaging with IR thermography (e.g., FLIR) or thermoreflectance imaging.

  • Accelerating thermal simulation through compact modeling, custom meshing or solvers, open-source tools, or machine learning.

• This role involves work that may be subject to U.S. export-control laws. Prahelika assesses access requirements for the specific work and, where needed, evaluates available government authorization options before granting access to controlled technology. Program assignments are subject to applicable legal requirements.

Preferred qualifications

• Package-level FEA of stacked or thinned die: warpage, microbump fatigue, die-attach delamination.

• Thermal or structural design for space or airborne hardware.

Responsibilities

• Set junction-to-package temperature targets for each product and define the thermal pathway across interconnects, interposers, and materials that the rest of the team designs around.

• Drive design choices on bonding tiers, die order, die attach, interposers, heat spreaders, interface materials, heat sinks, and cold plates.

• Analyze thermo-mechanical stress in heterogeneous assemblies: interface stress, warpage, fatigue, and mean time to failure for die attach, embedded die, and bumps.

• Build and run multi-scale, multi-physics simulations from real design data (GDSII layouts, 3D STEP models, .sip/.mcm, power maps), then correlate them against your own measurements on fabricated parts and feed the results into the next revision.

• Establish the thermal design flow and models that become part of Prahelika's design kit, and mentor the engineers who use them as the team grows.

How we work

• Engineers here work across the stack. Siloed circuit, device, and package engineers do not thrive at Prahelika; you will be expected to understand the electrical design and the manufacturing process well enough to argue with both.

• AI is a cornerstone of how we engineer. You will build your own workflows with tools such as Claude, ChatGPT, or Codex, compatible with Prahelika's AI ecosystem, with physically grounded checks on what they produce.

• No one is asked to cut a corner they would be ashamed to defend. If a deadline can only be met by skipping a reliability test, the deadline moves, and the engineer who refuses to sign off on something unsound is protected, not punished.

• Credit and authorship follow contribution, not seniority. If your name belongs on the work, it is there.

• Excellence of mind and body is a working condition, not a reward for finishing. Tired decisions end up in hardware; we expect you to sleep, train, and step away, and we do not mistake hours logged for work delivered.

Compensation and benefits

• $150K – $220K base salary plus founding-team equity. Final compensation depends on experience and skills.

• Full medical, dental, and vision coverage with HSA; 401(k) with 4% company match; daily meals.

How to apply

Apply using the form for this role. If available, please include a brief description of one project that best represents your work on this kind of problem; we read that more closely than a cover letter.

Prahelika is an equal opportunity employer. We hire on demonstrated ability, without regard to any protected characteristic.