Electronics protection against salt, fog and fluctuating humidity
Coastal areas, marine environments, road traffic, and industrial atmospheres expose electronics to a particularly aggressive combination of factors: salt, fog, and constantly changing humidity. This mixture is more corrosive than humidity alone. This article shows you how to reliably protect electronic components in saline environments.
To the point
For protection against salt spray and fluctuating humidity, a conformal coating for serial electronics, or a full silicone encapsulation for harsh, continuous use. Silicones are particularly robust here thanks to their hydrolysis and salt resistance across wide temperature ranges. Clean adhesion is crucial – otherwise, salt solutions will compromise the protective coating.
Why salt is so aggressive
Salt spray forms a moist, electrically conductive film on surfaces. This film drives two failure mechanisms: corrosion of metallizations and contacts, and leakage currents and tracking between live conductors. Fluctuating humidity exacerbates this because the salt film repeatedly dissolves, concentrates, and redeposits. Therefore, the tracking resistance (reference value CTI according to IEC 60112) becomes crucial on the surface, while the air and creepage distances according to IEC 60664-1.
Test
Salt resistance is assessed in the salt spray test according to ISO 9227 or IEC 60068-2-11 (test Ka), while fluctuating humidity is assessed via cyclic wet-heat tests according to IEC 60068-2-30. These tests accurately reflect the coastal and industrial climates that lead to premature failures in the field.
Build protection correctly
| Requirement | Solution |
|---|---|
| Standard electronics, lightweight, repairable | Conformal coating, applied without gaps |
| rugged, continuous use, Navy | Full encapsulation with elastic silicone |
| poorly adhering substrates | Cleaning + primer before protection |
Material selection and products
For thin-film protection: Electrolube APL acrylic protective coating; for maximum protection, a full encapsulation with SILISIL RTV MF-Flex 20 or PRO-Cast 45.Adhesion is crucial: On critical surfaces, a primer such as BLUESIL Primer PM 820 bonding, preventing salt solutions from undermining the protective coating. Related: Outdoor sensors and protection against condensation.
Frequently Asked Questions
Coating or encapsulation in salt spray environments? A coating is sufficient for moderate stress and series production; in harsh marine/outdoor applications, encapsulation provides more reliable protection.
What does ISO 9227 test? The salt spray test – resistance to a defined salt spray atmosphere, commonly used to assess corrosion and protective performance.
Why does electronics fail faster on the coast? Salt films are conductive and corrosive; together with fluctuating humidity, they significantly accelerate corrosion and leakage currents.
Consultation and samples
Tell us the application location, load, and required testing – we will recommend a coating or potting compound including primer and provide a sample. Contact us or write to info@silitech.ch.
