InsightsThe Underestimated Danger: How Moisture Affects Electronic Assemblies

Moisture can cause significant issues, so a good understanding of the risks and appropriate protective measures is crucial.

Moisture on electronic assembliesEffects of Moisture on Electronic Assemblies

The diverse consequences of moisture on electronic assemblies should not be underestimated. From short-term disruptions to long-lasting and severe damage, moisture can cause significant issues for the performance and lifespan of electronic components. Therefore, developing a comprehensive understanding of potential risks is crucial to taking appropriate protective measures.

Causes & Mechanisms How Moisture Reaches Electronic Assemblies

Moisture typically reaches an electronic assembly in two ways: through climatic influences during operation or gradually during the manufacturing process. If ambient temperature and relative humidity change rapidly, the surface temperature of the assembly can fall below the dew point, resulting in direct condensation.

During manufacturing, moisture can be introduced through insufficiently dried components, thermal fluctuations during soldering, or manual handling. Residues such as salts or perspiration are hygroscopic and actively attract moisture from the surrounding air. In addition, aged seals, capillary effects at connectors, or missing pressure equalization elements in the housing can allow moisture to penetrate the electronic system during operation and accumulate on the assembly.

failure mechanismsFailure Mechanisms Due to Moisture Influence

Moisture on an electronic assembly can cause a variety of failure modes, including:

Conductivity and Short Circuits

The situation becomes critical when moisture contains conductive contaminants or when contaminants dissolved by moisture reach the assemblies. This promotes the formation of connections between traces and components. Such short circuits can lead to the destruction of the assembly and, depending on its function, potentially pose dangerous consequences for people.

Oxidation and Corrosion / Electrochemical Migration

Moisture can promote the oxidation of metal contacts and connections on the assembly, leading to a deterioration of electrical conductivity. Electrochemical migration, a form of corrosion, also affects the reliability and lifespan of electronic assemblies and is often responsible for climate-related failures

Dielectric Constant

Moisture can increase the dielectric constant of insulation materials, affecting the electrical functionality of the assembly by increasing capacitance and causing signal distortion.

Thermal Properties

The penetration of moisture can also affect the thermal conductivity of materials, hindering the effective heat dissipation of components. This, in turn, can lead to excessive heat buildup and premature failure

risk MitigationEffective Protection Against Moisture

Preventive measures are essential to minimize the impact of moisture on electronic assemblies. These include:

Careful design selection: Consideration of creepage and clearance distances in accordance with standards such as IEC 60664-1, as well as the avoidance of critical geometries in the circuit layout.
Process and cleanliness control: Regular monitoring of ionic cleanliness and Technical Cleanliness in accordance with VDA 19 or the ZVEI guideline.
Suitable protection systems: Use of qualified protective systems such as conformal coatings or potting compounds to reduce moisture ingress.
Validation under climatic stress: Performance of standards based qualification tests such as condensation testing, SIR measurements according to IPC-TM-650, or environmental testing according to IEC 60068-2.

Achieving the right balance between circuit layout, protection system and manufacturing cleanliness requires a holistic assessment. Our expert team supports you in systematically evaluating and addressing these influencing factors during the development phase, during redesign, or in the event of qualification issues.

If you would like to assess the moisture-related risk of your electronic assembly within the overall system, or if you are facing a failure during climatic testing, you can find all information on our manufacturer-independent assessment methods on our dedicated page for risk assessment and Humidity Robustness of electronic assemblies: Maximum Humidity Robustness for Electronic Assemblies

Protection Against Moisture with Conformal Coating What Can Protective Coatings Achieve?

Protective coatings (conformal coatings) protect electronic assembly surfaces against moisture, condensation, condensation-related effects and aggressive environmental conditions. They form an insulating barrier that helps prevent surface leakage currents, electrochemical migration (ECM) and corrosion on the PCB.

For fast and reliable inspection and assessment of your protective coating, we offer specialized test methods:

ZESTRON Coating Layer Test: Fast, non-destructive visualization of coating thickness distribution and edge coverage on the electronic assembly.
Coating Reliability Test (CoRe Test): Assessment of the thermal, climatic and electrical robustness of the protective coating under stress.
Iodine Vapor Test: Targeted detection of microcracks, pinholes and wetting defects in the coating layer.

A protective coating can provide long-term protection only when the coating material, application process and assembly surface are optimally matched. Our expert team provides manufacturer-independent analysis of coating defects, adhesion problems and delamination to help ensure the reliability of your coating under field conditions.

Have Your Protective Coating Assessed

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The whitepaper discusses the impact of moisture on the reliability of power modules in renewable energy systems and electric vehicles. It explores how moisture can alter the typical failure mechanism from electrochemical migration (ECM) to anodic-cathodic migration (AMP) and provides specific case examples.

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