Accelerated aging
It is used to help determine the long-term effects of expected levels of stress within a shorter time, usually in a laboratory by controlled standard test methods.
Below are the most commonly used techniques: Samples are exposed to repeated cycles of extreme heat and cold, mimicking daily or seasonal temperature fluctuations.
In electronics, printed circuit boards (PCBs) are subjected to rapid temperature shifts to evaluate solder joint reliability and material resilience.
[1] For example, glass or ceramic components in aerospace applications are subjected to thermal shock tests to ensure durability under high-speed atmospheric reentry conditions.
[2][3] BGA components are particularly susceptible to failures induced by thermal shock due to the mechanical stresses exerted on solder joints during rapid temperature changes.
Research has shown that thermal shock can lead to the initiation and propagation of cracks within these solder joints, compromising the integrity and reliability of electronic assemblies.
In harsh environments characterized by significant temperature variations, these joints are prone to crack formation and eventual fracture, underscoring the importance of rigorous thermal shock testing in the design and assessment of electronic components.
For example, in the automotive sector,[6] components such as engine parts and safety equipment are tested to ensure they can withstand the thermal stresses encountered during operation.
- Humidity testing is often conducted in combination with elevated temperatures to accelerate the effects of moisture exposure, particularly for materials like polymers, metals, and composites.
Samples are exposed to controlled concentrations of oxygen or atmospheric pollutants (e.g., ozone or sulfur dioxide) to simulate oxidative degradation or corrosion.
By exposing specimens to a controlled saline environment, this accelerated aging test simulates the corrosive effects of marine and coastal conditions, providing valuable insights into a material's durability and longevity.
This form of testing is crucial for determining how substances react to environmental factors such as heat, humidity, oxidation, and exposure to aggressive chemicals.
High temperatures can accelerate oxidation, polymer degradation, and phase transitions, leading to reduced mechanical strength and altered performance characteristics.
[15] Chemical exposure testing examines the effects of contact with reactive substances, such as acids, bases, solvents, and oxidizing agents, on material stability.
This type of testing is essential for assessing long-term reliability, identifying failure modes, and improving product durability across industries such as aerospace, automotive, electronics, and pharmaceuticals.
For instance, an electronic device in an automotive setting may experience high temperatures, humidity, vibrations, and cyclic mechanical loads simultaneously.
The validation of aging test results is essential to ensure that the data obtained accurately represents the long-term performance and durability of a material, component, or product.
Key statistical methods used in validation include standard deviation analysis, confidence interval estimation, and regression modeling to establish trends over time.
[20] To validate aging test results, researchers compare experimental outcomes with actual field data collected from long-term use of the product in its intended environment.
For example, in automotive materials testing, exposure to controlled ultraviolet (UV) light and humidity in a lab must reflect the wear observed in outdoor vehicle surfaces over years of service.
Applications of accelerated aging include pharmaceuticals, medical devices, electronics, automotive materials, aerospace components, and consumer goods.
Stability testing follows guidelines such as those outlined in the International Council for Harmonisation (ICH) Q1A(R2), which establishes protocols for subjecting pharmaceuticals to elevated temperature and humidity conditions.
[27] In the automotive sector, accelerated aging is used to test polymers, coatings, adhesives, and structural materials for resistance to heat, UV exposure, humidity, and mechanical stress.
Additionally, corrosion testing such as SAE J2334 replicates environmental conditions, including salt spray and humidity, to evaluate metal durability in vehicle components.
[28] Accelerated aging was further refined during the 1920s, with tests using sunlight and elevated temperatures being used to rank the permanence of various papers in the United States and Sweden.
This led researchers like Baer and Lindström to advocate accelerated aging techniques using the Arrhenius equation and a realistic relative humidity.
