Most teams treat power electronics thermal management as a hardware problem to solve in the last sprint before tape-out. They often size a heatsink, choose a Thermal Interface Material (TIM), and hope the enclosure airflow is enough. In a lab at 25 °C, it usually is. But in a sealed industrial cabinet at 55 °C ambient, holding sustained load for eight months, it usually isn’t.
Power electronics thermal management is an architectural decision that ripples back into silicon choice, board copper budget, enclosure mechanics, and firmware power policy.
Bear in mind that it isn’t a single component. It is a layered system, and the cost of fixing it shifts by an order of magnitude with every layer you skip on the way in.
This article is the technical deep-dive we wish every hardware team had read before week one of an industrial product build, with specific reference to Arduino Pro-based devices. It applies whether you’re targeting Portenta H7, Portenta C33, Opta, or building custom around STM32H7 or Renesas RA silicon directly.
What power electronics thermal management actually means at the system level
It is the engineering practice of controlling where heat is generated, how it moves through the product, and what the silicon experiences across the full operating envelope. It spans silicon-level power policy, board-level conductive design, enclosure-level convection and radiation, and ambient-level envelope assumptions. A real solution covers all four.
Thermal management solutions sold as a single component — a heatsink, a TIM, a fan — solve at most one of those layers. They are useful, but they are not what a product needs when its job is to run reliably for a decade in a cabinet that bakes in summer and frosts in winter.
Thermal management engineering starts with one shift in posture: stop asking “what cooling do we add?” Start asking “where is the heat coming from, where does it need to go, and what’s stopping it?”
Arduino Pro thermal personalities — Portenta H7, Portenta C33, Opta
Each board in the line has its own thermal personality, and treating them as interchangeable is a fast way to over- or under-engineer the thermal stack.
Portenta H7 — dual-core, small footprint, big sustained-load headache
The Portenta H7 carries the STM32H747XI dual-core (Cortex-M7 @ 480 MHz + Cortex-M4 @ 240 MHz) on a compact module. Under brief workloads, it is thermally well-behaved. Under sustained dual-core load with Wi-Fi/Bluetooth Low Energy (BLE) active, package surface temperatures climb fast — particularly when the module is mounted on a baseboard that doesn’t extend the copper pour.
For industrial deployments running both cores, plan for either a top-side heatsink (Arduino Pro offers a heatsink kit for the Portenta H7), enclosure-stud conduction, or a firmware policy that holds the M7 below sustained 100% utilization.
Portenta C33 — Renesas RA6M5, lower dissipation, different thermal calculus
The Portenta C33 uses the Renesas RA6M5 (Arm Cortex-M33 @ 200 MHz). Total dissipation is meaningfully lower than the H7, which simplifies the thermal stack — often enough to skip the heatsink entirely in a moderately ventilated enclosure. The tradeoff is compute headroom. For products where the workload fits comfortably inside the C33’s envelope, this is the easier thermal path.
Opta — industrial PLC envelope baked in, but not without its choices
The Opta family is Arduino Pro’s industrial PLC line. Operating envelope and conformal coating are designed for cabinet deployment. That doesn’t mean thermal is free — sustained Ethernet traffic, relay switching, and on-board logic still generate heat that has to leave the enclosure. Opta’s mechanical helps; firmware power policy and enclosure mounting still matter.
The pattern across the line: Arduino Pro solves the platform side of the equation for industrial products. The engineering team — internal or partnered — still owns the thermal stack that sits around it. The DeepSea Arduino Pro thermal management practice is built around exactly that division of labor.
Active thermal management vs. passive
Active thermal management — fans, blowers, Peltier modules, liquid loops — solves heat removal when passive methods can’t. It costs power, adds moving parts, adds failure modes, and adds noise. Passive thermal management — copper, TIMs, heatsinks, enclosure conduction — is reliability-positive, power-positive, and silent, but capacity-limited.
The honest answer in industrial product design:
The rows above are starting points, not destinations. Real numbers from real validation drive the actual choice.
The thermal management controller — firmware as a first-class citizen of the design
A thermal management controller, in modern industrial products, is rarely a dedicated IC. It is firmware that reads on-die and board-mounted temperature sensors, decides what to throttle, and ships its policy as OTA-deployable updates. This is the layer most thermal management companies skip — and it is the layer that distinguishes a product that runs at the edge from a product that dies at the edge.
A well-designed thermal management controller includes:
Real telemetry from the field. Die temperature, board-mount sensor readings, and inferred ambient logged at intervals that capture the duty cycle, not just the average. Phoned home and visualized.
A throttling ladder, not a cliff. Reduce clock, then gate peripherals, then drop duty cycle, then enter safe mode — in that order, with hysteresis to prevent oscillation.
OTA-deployable thermal policy. When the field tells you the envelope was optimistic, you change the policy without changing the hardware.
Graceful degradation. When the system has to throttle, it should preserve the most important workloads and shed the least important ones. The product’s value proposition tells you which is which.
This is where partner-tech fluency matters: the same throttling logic looks different in firmware on a Portenta H7 (Cortex Microcontroller Software Interface Standard (CMSIS) / STM32 Hardware Abstraction Layer (HAL) primitives) than on a Portenta C33 (Renesas Flexible Software Package (FSP)) than on a custom STM32 design. Teams that have shipped across multiple families know which abstractions transfer and which don’t.
Thermal validation across the industrial envelope (not the bench)
A thermal design isn’t a thermal design until it has been validated across the real envelope. That means thermal-chamber testing at the worst-case ambient, with the worst-case sustained workload, for long enough to reach steady state. It means thermal imaging under load to find the hotspots a sensor count of two can’t detect. It means burn-in runs that match the duty cycle the product will see in deployment.
The output is a die-temperature curve as a function of ambient, with the throttle thresholds marked. If that curve does not exist before a product ships, the product is shipping on hope. We have seen “thermal management solutions for electronic equipment” delivered without one, and the field always finds out first.
Where do teams get power electronics thermal management wrong?
Three failure patterns repeat across the projects we get called in to triage:
The first is locking the mechanical enclosure before the thermal architecture review. Once the mechanical is frozen, your thermal design is bound by mechanical choices made for cosmetic or assembly reasons. The cheap thermal wins disappear; the expensive active solutions arrive.
The second is assuming the SoC datasheet’s thermal numbers describe your product. Datasheet thermal numbers are typically for a reference layout in still air at a benign ambient. Your industrial product is none of those. Simulate against your actual board. Validate against your actual enclosure.
The third is treating firmware power policy as a future feature. The team ships with the CPU at 100% because it’s easier, plans to add throttling “in v1.1”, and never does — because by the time the field reports thermal failures, the team is on v2.0 and the thermal debt is now a recall risk.
Integrated thermal management solutions for products that have to last
Power electronics thermal management is integrated by definition: silicon, board, enclosure, ambient, and firmware. For instance, the teams shipping reliable industrial products on Arduino Pro and adjacent partner-tech are the ones who own all five layers from week one, not the ones who buy a heatsink in week twenty.
If you’re working on a custom industrial product where thermal is on the critical path — Portenta H7, Portenta C33, Opta, or a fully custom design around STM32 / Renesas RA / Espressif — that’s the engagement DeepSea Developments runs. We can meet with you to analyze your project. Click on the button below to know more.
