Do you know what the main environmental stresses are that cause electronic products to fail?

Reliability of electronic products is a critical metric for assessing their performance. Whether for civilian or military applications, reliability remains one of the primary concerns for both product developers and users. During operation, electronic devices are subjected not only to electrical stresses like voltage and current but also to environmental factors such as high-and-low temperature cycling, mechanical vibration and shock, salt spray exposure, and electromagnetic fields. Under these environmental stress conditions, products may experience performance degradation, parameter drift, material corrosion, or even complete failure. Therefore, to ensure the effective functionality of electronic devices, it is typically necessary to conduct a series of tests and evaluations. Environmental Simulation Testing 。

During the use of electronic products, environmental stresses cause continuous changes in the product's physical, chemical, mechanical, and electrical properties. The nature of these changes depends on the type and magnitude of the environmental stress applied. Below, we introduce several typical environmental stress factors.

1. Temperature Stress

Temperature stress is categorized into steady-state temperature stress and cyclic temperature stress. Steady-state temperature stress refers to the temperature response of an electronic product when it operates or is stored under a specific thermal environment. If this response exceeds the product’s tolerance limit, components may undergo softening, deformation, or experience a decline in insulation performance—and in extreme cases, even overheating and subsequent burnout. In such instances, the product is subjected to high-temperature overstress, which can lead to immediate failure within a very short period. On the other hand, if the response temperature remains within the product’s specified operating temperature range, prolonged exposure to steady-state temperature stress will gradually degrade the material properties, causing shifts in electrical performance parameters over time, ultimately resulting in product failure.

Thermal stress due to temperature changes refers to the thermal stress generated at material interfaces in electronic products when they are exposed to varying temperatures, caused by differences in the thermal expansion coefficients of the constituent materials. When temperature fluctuations are abrupt, this can lead to instantaneous cracking and failure at the material interfaces—resulting in what’s known as over-stress from temperature variation, or temperature shock stress. Conversely, if temperature changes occur more gradually, microcracks may form in localized areas, progressively accumulating over time. These cracks eventually cause the material interfaces to delaminate or fail entirely. By Environmental Simulation Testing Relevant tests and inspections can be conducted to evaluate the product under varying temperature stresses.

2. Mechanical Stress

Electronic devices are subjected to three types of mechanical stress: mechanical vibration, mechanical shock, and constant acceleration (centrifugal force).

Mechanical vibration stress refers to the type of mechanical stress generated when electronic products undergo reciprocating motion around an equilibrium position under external environmental forces. The effects of mechanical vibration on electronic devices include deformation, bending, cracking, and even fracture caused by the vibrations themselves. Over time, exposure to continuous vibration stress can lead to fatigue-induced cracking at structural interface materials, ultimately resulting in mechanical fatigue failure.

Mechanical impact stress refers to the type of mechanical stress that occurs when an electronic product experiences a single, direct interaction with another object (or component) under external environmental forces, resulting in an abrupt change—such as force, displacement, velocity, or acceleration—instantaneously. Under the influence of mechanical impact stress, the product can rapidly release and transfer a significant amount of energy within an extremely short time frame, often leading to severe damage.

Constant acceleration (centrifugal force) stress refers to the centrifugal force generated when electronic products operate on a moving platform, caused by the continuous change in the direction of the platform's motion. This is a virtual inertial force that causes rotating objects to constantly tend to move away from the center of rotation. The centrifugal force is equal in magnitude but opposite in direction to the centripetal force. Once the centripetal force—resulting from the net external force acting toward the center of the circle—disappears, the rotating object will no longer maintain its circular motion and will instead fly off along the tangent to its current trajectory, potentially leading to product failure at that critical moment.

3. Moisture Stress

Moisture stress refers to the damp conditions that electronic products experience when operating in an atmosphere with a certain level of humidity. Electronics are highly sensitive to moisture—once the relative humidity in the environment exceeds 30% RH, the metal components of the product may begin to corrode, potentially causing electrical performance parameters to drift or fall outside acceptable tolerances.

For example, under prolonged exposure to high humidity, insulating materials absorb moisture, leading to a decline in their insulation performance—potentially causing short circuits or even dangerous high-voltage shocks. In the case of contact-based electronic components like plugs and sockets, moisture on their surfaces can easily trigger corrosion, forming oxide films that increase electrical resistance at the contact points. In severe cases, this can result in complete circuit failure. Additionally, in extremely humid environments, fog or water vapor may cause sparks when relay contacts move, rendering the relay inoperable. Semiconductor chips are particularly sensitive to moisture; if the moisture level on their surfaces exceeds safe limits, the aluminum wiring inside can corrode at an alarming rate. To prevent electronic components from being damaged by moisture, encapsulation or hermetic sealing techniques are employed, effectively isolating the components from both the external atmosphere and potential contaminants.

Electronic devices are subjected to moisture stress due to water vapor adsorbed on the surfaces of materials and infiltrating into components within their operating environments—both from external sources and internal pathways. The severity of this moisture stress is directly linked to the level of ambient humidity. In China's southeastern coastal regions, humidity levels are particularly high, especially during spring and summer, with relative humidity often spiking above 90% RH. As a result, moisture-related challenges become an unavoidable issue. To address this, it is possible to: Environmental Simulation Testing The steady-state damp-heat test and the humidity resistance test evaluate the adaptability of electronic products when used or stored under high-humidity conditions.

4. Salt Spray Stress

Salt spray stress refers to the corrosive forces exerted on the surface of electronic components when they operate in an atmospheric environment filled with tiny salt-containing droplets. These salt droplets typically originate from marine climates or inland saline lake regions, primarily composed of NaCl and water vapor. The presence of Na⁺ and Cl⁻ ions is the root cause of corrosion in metallic materials. When salt spray settles on insulating surfaces, it significantly reduces the surface resistance; moreover, if the insulator absorbs the salty solution, its bulk conductivity can drop by as much as four orders of magnitude. On moving mechanical parts, salt spray-induced corrosion not only increases friction but can even lead to severe jamming or seizing of moving components. Although encapsulation and hermetic sealing techniques are often employed to protect semiconductor chips from corrosion, external leads of electronic devices still frequently fail due to rusting caused by salt spray exposure. Additionally, corrosion products on printed circuit boards (PCBs) may inadvertently short-circuit adjacent traces. Ultimately, the salt spray stress experienced by electronic devices arises directly from the salt-laden atmosphere—particularly in coastal areas or aboard ships and vessels, where airborne salt concentrations are especially high, posing significant challenges to the reliability and longevity of electronic component packaging. Environmental Simulation Testing — Evaluating the adaptability of electronic packaging to salt spray by assessing how the salt spray test accelerates corrosion.

5. Electromagnetic Stress

Electromagnetic stress refers to the electromagnetic forces that electronic products experience when exposed to an electromagnetic field—specifically, one where electric and magnetic fields interact and fluctuate over time. An electromagnetic field consists of two key components: the electric field and the magnetic field. A time-varying electric field generates a magnetic field, while a time-varying magnetic field, in turn, induces an electric field. These two fields continuously reinforce each other, driving the propagation of electromagnetic waves. For electronic components, electromagnetic interference (EMI) within the electromagnetic field is a major factor affecting their electromagnetic compatibility (EMC). Such EMI can originate either from internal interactions between components inside the device or from external electronic equipment, potentially causing significant disruptions to the performance and functionality of the product. For instance, if magnetic components within a DC/DC power module generate electromagnetic interference that affects nearby electronic devices, it could directly impact critical output parameters like ripple voltage. Similarly, radio-frequency radiation might penetrate through the product’s outer casing, entering the internal circuitry, or couple into the system via interface cables, leading to conducted interference that further degrades performance.