The Silent PCB Killer: Solving Humidity-Induced Electronics Failures with Simulation
Published: August 03, 2026
As our world rapidly transitions toward electric vehicles, smart grids, decentralized renewable energy, and massive cloud data centers, high-power electronics are being pushed to their absolute physical limits. To maximize efficiency and reduce charge times, engineers are designing circuits that handle higher operating voltages than ever before. However, this push for higher power exposes electronic hardware to a subtle, yet highly destructive environmental threat: humidity.
While thermal management usually dominates the design conversation, ambient moisture and condensation represent some of the most challenging failure vectors in hardware engineering. When relative humidity spikes, moisture forms a thin liquid film across a printed circuit board (PCB) surface. Under a voltage bias, this microscopic water layer triggers electrochemical reactions that can destroy a circuit in moments. Understanding, predicting, and preventing these failures is the primary focus of the Centre for Electronic Corrosion (CELCORR) at the Technical University of Denmark (DTU).
The Mystery of the "Unidentified" Board Failure
In the field of electronics reliability, diagnosing moisture-related damage is notoriously difficult. Many engineers have encountered a scenario where a device fails in the field, but works perfectly once brought back to the lab for analysis. According to Dr. Rajan Ambat, a professor at DTU and head of CELCORR, roughly half of all electronics failures are returned with an "unidentified root cause" tag.
The explanation for this mystery is simple yet frustrating: the offending moisture evaporates. Once the device is opened or brought into a dry testing environment, the water film vanishes, leaving virtually no trace of its presence. Unless the moisture has persisted long enough to cause visible corrosion or structural metal dendrites, failure analysts are often left guessing. This lack of diagnostic visibility makes it incredibly difficult to design preventative measures into next-generation hardware.
How Moisture Destroys Modern Circuits
To mitigate these failures, we must first understand the physics of moisture on a PCB. When ambient air reaches its dew point, water condenses on the board’s surface, bridging the gaps between adjacent copper traces, surface-mount pads, and component pins. Even a water film as thin as 10 micrometers is sufficient to create an active electrolyte path.
Once this conductive liquid bridge is established between two electrodes with opposing electrical potentials, an electrochemical process begins:
- Stray Leakage Currents: The presence of water and dissolved surface contaminants (like flux residues or atmospheric salts) dramatically lowers electrical resistance, allowing current to leak across paths meant to be isolated.
- Electrochemical Migration (ECM): Metal ions dissolve from the anode (positive electrode) and migrate through the liquid film toward the cathode (negative electrode).
- Dendrite Formation: Over time, these migrating ions deposit on the cathode, growing outward in thin, needle-like metallic structures called dendrites. Once a dendrite spans the entire gap to the anode, it causes a catastrophic direct short circuit.
In high-voltage systems—such as solar inverters, electric vehicle battery management systems (BMS), or industrial wind turbine controllers—these leak currents and shorts do not just disable the system; they can cause catastrophic thermal runaway, sparking, and electrical fires.
Bridging Materials Science and Electrical Design
To combat this silent threat, CELCORR serves as an interdisciplinary bridge between materials science and traditional electronics engineering. Historically, these two fields operated in silos: materials scientists understood corrosion physics, while electronics designers focused on schematics, layout, and software. By uniting these disciplines, researchers are developing modeling techniques to predict how environmental conditions impact specific physical PCB layouts.
Collaborating with industrial partners and researchers at Aalborg University, the CELCORR team utilized COMSOL Multiphysics software to build detailed simulation models. They designed a virtual test circuit board that mirrored real-world geometries and simulated a thin condensation layer on top of the traces. By altering variables such as electrode spacing, water film thickness, water conductivity, and applied voltage, they could precisely compute the resulting electrochemical leakage currents.
This virtual testing approach offers hardware designers a safe, fast, and repeatable way to evaluate different board layouts. Instead of spending weeks building prototypes and waiting for them to corrode inside environmental test chambers, engineers can iterate layouts on a computer to optimize moisture resistance in minutes.
Democratizing Physics with Custom Simulation Apps
While advanced multiphysics models are incredibly powerful, they are often too complex for everyday hardware developers to configure from scratch. To solve this usability issue, CELCORR utilized the Application Builder within COMSOL to package their highly complex calculations into simple, web-accessible simulation applications.
These custom apps present a streamlined, parameter-driven user interface. Users do not need to understand the underlying partial differential equations governing electrochemistry. Instead, they can input practical engineering values, such as:
- Distance between conductive traces
- Applied voltage levels
- Thickness and conductivity of the anticipated moisture layer
- Physical obstructions or conformal coating layouts
The simulation app instantly calculates the expected leakage current and displays clear, visual streamline plots showing how ions will travel across the board. This simplified "plug-and-play" interface allows hardware designers to immediately see how minor spacing changes or material choices affect the overall robustness of their design.
Designing for Harsh Environments: Key Takeaways
For embedded developers, IoT engineers, and DIY makers, the research coming out of DTU and CELCORR highlights several critical design principles for ruggedizing hardware:
- Increase Trace Spacing (Creepage and Clearance): In high-humidity environments, keeping high-voltage traces as far apart as possible is the primary defense against leakage currents and dendritic growth.
- Enclosure Design and Venting: Protecting electronics requires a careful balance. Completely sealed enclosures can trap humidity inside, leading to internal condensation when temperatures drop. Smart venting or desiccant integration is often necessary.
- Conformal Coating Application: Applying a protective polymeric film over the PCB acts as a physical barrier against moisture. However, poor application can leave micro-pinholes where condensation can still collect and accelerate localized corrosion.
- Cleanliness in Manufacturing: Ionic contaminants left behind from manual soldering flux act as salts that dramatically increase the electrical conductivity of any condensed water. Thoroughly cleaning boards post-assembly is vital for harsh-environment longevity.
The Future of Climate-Robust Electronics
Looking ahead, CELCORR is expanding its research to tackle increasingly complex scenarios. Backed by a grant from the Grundfos Foundation, the group has established the Centre for Climate Robust Electronics Design (CRED). This new initiative is focused on exploring the unique challenges of extra-high-voltage and high-power applications, developing even more advanced tertiary current distribution models to simulate mass transport properties and chemical reaction rates.
By integrating material science, simulation modeling, and accessible design tools, researchers are paving the way for a more reliable, electrification-friendly future—ensuring that our critical green energy and automotive systems can withstand the harshest climates on Earth.
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Original news rewritten with AI for educational purposes.
