TRM vs HyperLynx Thermal — should you switch?

Same family of physics

Both tools solve board-level coupled electrical-thermal: copper resistance that rises with temperature, current density on traces, plane heating, via thermal paths, component dissipation. Neither is a CFD tool. Both produce engineering-grade answers in the regime that matters for sign-off — not at the chassis-airflow level. So the question is rarely “which solver is more accurate.” It’s “which one fits how I actually work, and what does the rest of my organization use?”

Workflow + CAD ecosystem

HyperLynx is part of Siemens EDA. Its center of gravity is round-tripping with Xpedition (and increasingly Capital-EE for the electrical side) — stackup, via models, net lists, and back-annotation. If your team lives in that flow, HyperLynx’s ergonomics are hard to beat: changes don’t need re-export, and the meshing is reasonable because it understands the Siemens stackup model natively.

TRM is CAD-agnostic but optimized for Altium Designer round-tripping (Adam Research has put real work into the Altium integration), plus standard Gerber/ODB++ in and out. If you’re an Altium shop, that’s a step-function improvement over importing through HyperLynx. If you’re a KiCad or Orcad shop, TRM is the one that’s actively working on you; HyperLynx will not be.

Coupled PDN + thermal

This is where TRM pulls ahead. TRM solves DC IR-drop, current density, and thermal as one coupled system: when copper heats up, it carries less current; that changes the IR-drop map; which changes the dissipation; which changes the heat map. Iteration to consistency is in the solver. HyperLynx Thermal can do PDN, but typically as a separate workflow (or a separate seat) that you couple by hand.

For a board where the rails are the constraint — high-current digital, point-of-load arrays, EV/automotive 48 V — coupled is the only honest analysis. You feel the difference when a 20 A rail says it’s fine at 25 °C and quietly drops 8% of its budget at 85 °C.

Transient + fault analysis

TRM’s transient solver runs cold-crank, inrush, power-cycling and fault scenarios with thermocouple-style time plots at any pin. HyperLynx Thermal has a transient mode; in our experience it requires more setup and is less commonly used in real shops. If your design lives or dies on cycling (BMS, traction inverter, photonics burst-mode), the TRM transient flow saves real hours per analysis.

Seat cost + licensing

HyperLynx Thermal seats land in the $15–25k/year band per seat, often bundled with other HyperLynx tools. TRM single-seat lands at $2.5–6k/year, transparent and on the website. For a 3-engineer team, that’s the difference between everyone simulating and one person being the “sim guy” everyone queues behind. Bottleneck removal is itself a sign-off improvement.

Verdict by shop type

Siemens shop, large, HyperLynx already paid for. Stay. The Xpedition round-trip is worth more than the TRM deltas above. Add TRM only if you have a transient-heavy program HyperLynx is slowing you down on.

Altium shop. TRM is the right add. The integration, coupled PDN, and seat cost together compound the EE-hours value.

KiCad or Orcad shop. TRM is the only option that’s actually working to integrate with you. HyperLynx will not.

Small team, any stack. TRM. The math is that you can put a seat on every engineer for the price of one HyperLynx seat, and the bottleneck goes away.

The right comparison isn’t “which solver is more right” — both are good enough for sign-off in this regime. It’s “which one lets every engineer simulate, today, in the CAD I already use.”

Try it

TRM has a 14-day trial with sample boards (no sales call). For a fuller comparison incl. Icepak and SolidWorks Flow, see TRM vs Icepak vs HyperLynx — the honest comparison. If you want us to run your board, that’s PhySignoff.