Four Major Environmental Factors Causing Electronics Failure: Moisture Absorption, Thermal Circumstance, Air Pressure, and Dust.
On modern electronic devices, product reliability not only depends on design and manufacturing, but also significantly influenced by the environment.
This article provides an in-depth, comprehensive analysis of four environmental factors—moisture absorption, thermal circumstances (heat and cold), air pressure, and dust—and the negative impacts with potential threats which may pose on electronic performance.
What are hygroscopicity and adsorption?
The ability of an object to absorb moisture from the air is known as hygroscopicity, it occurs in two forms: surface absorption and volume absorption:
• Surface absorption: Known as adsorption, the moisture only stay on the surface but won’t soak in depth.
• Volume absorption: The process of moisture absorption throughout the entire volume.
Moisture absorption characteristics of various materials:
• Porous or fibrous materials: Absorb moisture primarily through capillary action. When relative humidity approaches 90%, the thickness of the water layer increases sharply.
• Ionic structure materials (e.g., glass): Exhibit significant water vapor adsorption.
• Materials composed of low-polarity or non-polar molecules (e.g., paraffin wax, fluoroplastics): Exhibit weak vapor adsorption.
• Condensation: Depends on the vapor pressure filling the space and the curvature of the liquid meniscus.
Note: For organic materials, moisture absorption refers to the slow process of activated diffusion of water vapor within the material, which contains some aqueous solution.
For materials of the same thickness, moisture absorption curves differ because the time required to reach equilibrium varies.
How do heat and cold affect electronic product performance?
During PCBA assembly, ignorant of dimensional changes—specifically the mismatch in Coefficients of Thermal Expansion (CTE) among various components—might lead to deformation, warping, and stress-induced solder joint fractures caused by thermal expansion stress.
Key impacts include:
1) Changes in mechanical properties:
When temperatures fluctuate rapidly across the 0°C threshold, components experience uneven rates of temperature change; the rate at which a structural material’s temperature changes depends on its thermal conductivity.
2) Degradation of electrical performance:
Thermal factors alter material properties, leading to a loss of mechanical and electrical integrity. Temperature fluctuations can cause changes in capacitor capacitance and a reduction in insulation resistance. Additionally, at temperatures below 233K, certain insulating varnishes may peel or crack.
3) Material embrittlement:
Rapid temperature fluctuations cause changes in intermolecular spacing, thereby affecting internal structural stress. This manifests initially as dimensional changes; due to differences in expansion coefficients, the material hardens or even cracks as it contracts upon cooling.
4) Corrosion and permeation:
When metals are used alongside plastics, mismatched coefficients of thermal expansion (CTE) prevent the two materials from expanding and contracting in unison. This inevitably creates gaps between the metal and plastic components, providing pathways for moisture to penetrate into the sealed product.
5) Micro-cracks:
Drastic temperature changes can cause thermosetting plastics to develop micro-cracks due to stress-induced fracture; these cracks widen during subsequent cycles of thermal expansion and contraction, thereby compromising the plastic’s moisture resistance.
How does atmospheric pressure affect the performance of electronic products?
Atmospheric pressure at ground level is influenced by weather conditions, while pressure decreases as altitude increases.
Risks associated with low atmospheric pressure:
• Reduced dielectric strength: Lower atmospheric pressure reduces the dielectric strength of air, lowering the breakdown voltage between contacts of opposite polarity and decreasing the surface resistance of insulating components.
• Corona discharge: Low pressure can trigger phenomena such as spark discharge, dielectric breakdown, and corona discharge.
• Reduced heat dissipation: At low pressures, the thermal conductivity of air decreases, impairing the equipment’s heat dissipation performance.
How dust affects the performance of electronic products?
Dust carries electric ions, when combined with airborne fibers in high-humidity environments (such as rainy days):
1) It further impedes heat dissipation and creates a risk of short circuits between closely spaced components (e.g., micro-shorts caused by dendrite formation and reduced insulation performance);
2) Salt content in the dust absorbs moisture after settling on surfaces, leading to surface corrosion;
3) It reduces insulation resistance between circuits, increasing leakage current and signal interference (e.g., in radio receiving equipment);
4) It fosters mold growth;
5) In equipment relying on cooling fans, dust accumulates on the fan blades, creating resistance and reducing cooling efficiency;
Conclusion
To prevent environmental factors from negatively impacts on electronics — and to ensure operational performance, stability, and longevity while avoiding potential failure risks—users should observe the following for daily use and maintenance:
- Maintain appropriate environmental humidity;
- Avoid rapid, significant fluctuations in ambient temperature (e.g., extreme temperature cycling);
- Keep the environment free or lesser of dust;
