Taking the Heat: Thermo-Mechanical Failure Modes in Electronics

This week, it was widely reported that Ford Motor Company is recalling nearly 1.74 million vehicles due to rearview camera display issues. This includes nearly 850,000 vehicles being recalled due to a potential risk that their Accessory Protocol Interface Modules (APIMs) may overheat and not display images properly.

How did we get here? Electronics have rapidly proliferated and are now present in nearly every aspect of modern life. In addition to vehicles, household appliances, medical equipment, and industrial machinery that were once primarily mechanical now incorporate complex electronic controls, sensors, and computing components. From smartphones and wearable devices to smart homes and advanced transportation systems, electronics have become essential for communication, automation, and informatics. As this integration expands, ensuring the reliability of electronic systems under a wide range of environmental conditions, including extreme temperatures, has become increasingly important.

Electronic devices rely not only on electrical performance but also on mechanical stability. Inside every device are solder joints, connectors, circuit boards, and structural materials that must remain physically intact for the system to function. When electronics are exposed to temperature differences, these mechanical structures can degrade or fail.

Understanding the mechanical failure modes caused by temperature extremes is essential in aerospace, the auto industry, consumer electronics, and industrial systems.

Thermal Expansion and Contraction

All materials expand when heated and contract when cooled. This behavior is described by the coefficient of thermal expansion (CTE). In electronics, different materials such as silicon chips, copper traces, solder, and fiberglass circuit boards expand at different rates.

When temperatures fluctuate:

• Materials expand or contract by different amounts

• Mechanical stress develops at the interfaces between materials

• Repeated cycles of stress can lead to fatigue and eventual failure

This process is commonly referred to as thermal cycling fatigue damage.

Solder Joint Fatigue from Temperature Cycling

Solder joints connect electronic components to printed circuit boards (PCBs). These joints are particularly vulnerable to temperature-induced mechanical stress.

Failure Mechanism

• The component and PCB expand at different rates

• The solder joint is forced to deform repeatedly

• Microcracks begin to form in the solder

• Over time, these cracks grow until the electrical connection fails

Common Symptoms

• Intermittent electrical connections

• Devices that fail when warm but work when cold

• Complete circuit failure after prolonged temperature cycling

This failure mode is common in devices exposed to frequent temperature fluctuations.

Plated Through Hole and Via Fatigue from Temperature Cycling

Plated through holes and vias provide electrical connections between layers in multilayer printed circuit boards. Each heating and cooling cycle causes the plated copper inside the via barrel to stretch and compress slightly.

Over time, these repeated strains can lead to fatigue damage in the copper plating. Small cracks may begin to form within the barrel of the via, often at areas of high stress such as the knee of the via near the surface layers or at internal layer interfaces. As temperature cycling continues, these cracks can propagate through the copper wall.

Factors in plated through hole fatigue:

• Thickness of the copper plating in the via barrel

• Thickness of the printed circuit board

• Magnitude and frequency of temperature cycles

• Difference in thermal expansion between copper and the laminate material

• Mechanical constraints from mounted components

Design and manufacturing practices can reduce the risk of copper via fatigue. Thicker copper plating and materials with better CTE matching help improve reliability.

Printed Circuit Board Warpage

Printed circuit boards are typically made from fiberglass reinforced epoxy laminates. High temperatures can soften the epoxy matrix, allowing the board to deform or warp.

Effects of PCB Warping

• Misalignment of connectors

• Mechanical strain on solder joints

• Poor contact between components and the board

• Microfractures in copper traces

In severe cases, warping can cause components to detach from the board.

Consequences

• Loss of electrical connections between layers

• Reduced mechanical strength

• Permanent structural damage to the board

Semiconductor Package Cracking

Integrated circuits are enclosed in protective packages made of plastic or ceramic materials. Temperature changes can induce mechanical stress between the semiconductor die and the package.

Potential failures include:

• Die cracking

• Bond wire breakage

• Die separation from the substrate

• Underfill delamination

• Thermal interface material (TIM) pump-out

• Intermetallic fracture

Thermal shock increases the risk of these failures because materials do not have sufficient time to expand or contract gradually.

Key Takeaway

Understanding these mechanical failure modes is essential for engineers designing reliable electronic systems. By considering thermal expansion effects, selecting compatible materials, and implementing proper thermal management strategies, designers can reduce the risk of temperature-related damage. As electronics continue to be integrated into more environments and applications, building in thermal and mechanical reliability will be key to ensuring long term device performance and durability.

Copyright Gil Sharon March 10, 2026 . All rights reserved.