Humidity is well known to cause damage to electronic components. One of the primary ways humidity reduces the lifespan of electric actuators is through ionic migration short circuits.
1. What is Ionic Migration Short Circuit?
Ionic migration occurs when moisture and contaminants on a circuit board facilitate the movement of ions between conductors, leading to short circuits. The process follows these steps:
1️⃣ Presence of an electric field between two conductors on an insulator.
2️⃣ Electrolytic reaction occurs at the anode, releasing metal ions.
3️⃣ Ions migrate under the influence of the electric field toward the cathode.
4️⃣ Once enough ions accumulate at the cathode, a conductive bridge forms, causing a short circuit.
This leads to the failure of the actuator’s PCBA (Printed Circuit Board Assembly).
2. Common Causes of Ionic Migration on PCBA
Ionic migration short circuits typically occur in the following conditions:
✔ Impurities and moisture on PCB substrate
✔ Residual electrolytes from plating processes left in PCB holes
✔ Flux, adhesives, or other electrolytic materials used during PCBA manufacturing
✔ Dust, ionic contamination, and condensation accumulated on the PCBA over time
3. Preventive Measures Against Ionic Migration
To extend the lifespan of electric actuators and prevent failures due to humidity, the following measures are recommended:
✅ Apply Conformal Coating (Three-Proofing Paint)
Coating the PCBA with a conformal coating protects it from dust, moisture, and contaminants.
This is one of the most effective measures to prevent ionic migration.
✅ Fully Encapsulate the PCBA
In high-humidity or applications with large temperature fluctuations, fully encapsulating the circuit board provides the highest level of protection.
✅ Use a Dehumidifying Heater (PTC Heater)
Installing a PTC dehumidifying heater helps reduce humidity inside the sealed enclosure.
However, in IP67+ fully sealed enclosures, dehumidifying heaters may not immediately reduce air humidity at the initial heating stage.
Therefore, in certain situations, it may not completely prevent ionic migration short circuits.
By implementing these protective measures, the reliability and lifespan of electric actuators can be greatly improved, ensuring stable performance in humid environments.
