When selecting components for new circuit boards, the focus is often on board-level reliability, with the assumption that it will ensure component-level reliability and prevent part failures. This is somewhat accurate: intelligent circuit board design and PCBA decisions can mitigate or prevent potential issues leading to component failure. However, some components are inherently more prone to failure than others. Additionally, many times, when a failure occurs, people tend to discard or replace the entire board rather than investigate the root cause of the failure. Many issues can be traced back to one or more faulty components, so it's important to understand which are the most common failure-prone electronic components. It's equally crucial to know what board-level issues may contribute to these failures and which alternatives should be used to ensure a longer system lifespan.
Common Electronic Component Failures
Let's explore some of the most frequent electronic component failures. As we'll see, these failures aren't limited to specific components—rather, the function, location, and type of components can make them more prone to failure in various ways.
BJTs and MOSFETs Under High Temperature
Unlike some other temperature-sensitive components, MOSFETs tend to fail almost immediately when their junction temperature exceeds the rated specification. BJTs show similar behavior. As the temperature increases during operation, their conduction resistance also rises, which leads to higher losses and further temperature increases, creating a positive feedback loop known as thermal runaway. This issue not only occurs in MOSFETs but also in components like varistors and tantalum capacitors. However, this phenomenon is rare in integrated circuits (ICs), as they are more susceptible to other stress factors. Power MOSFETs include heat sinks to dissipate heat and prevent overheating.
Components Vulnerable to Discharge or Power Surges
Power surges can cause overvoltage breakdown in unprotected systems. The most obvious impact occurs in the power rectification and regulation sections of the circuit, where capacitors may experience overvoltage and breakdown during a surge. Electrostatic discharge (ESD) isn't exactly the same as power surges, but similar overvoltage protection measures can be applied.
ICs are particularly vulnerable to large ESD events, which is why semiconductor manufacturers incorporate ESD protection in their products. Moreover, standards like IEC 61000-4-2 outline ESD protection requirements to ensure the safety and reliability of products. Using components with integrated ESD protection reduces sensitivity to smaller ESD events.
Overvoltage and Overcurrent
While technically any component can fail due to overvoltage or overcurrent, some components are more likely to experience these issues, regardless of ESD pulses or power surges. Without ESD pulses, overvoltage due to design issues can cause an IC to latch up, creating a low-impedance path between the power rail and ground, leading to overcurrent and overheating. Preventing this requires careful selection of power regulators capable of maintaining proper voltage levels for the ICs.
Components Sensitive to Humidity
Electronics are rated with a "moisture sensitivity level" (MSL), which defines how quickly they absorb moisture. MSL ratings range from level 1 (components can be exposed to moisture indefinitely) to level 6. If humidity is a potential issue or failure cause, choose components with low MSL ratings. If using high MSL components, consider conformal coating to protect both the components and the circuit board from moisture damage, including oxidation.
Extreme corrosion is a significant risk from humidity exposure, but moisture can also infiltrate component packaging during manufacturing.
Temperature-Sensitive Components
All components are temperature-sensitive, and equipment deployed in extreme environments should use components with an appropriate operating temperature range. Besides simple overheating or freezing, thermal cycling and thermal shock are major contributors to component failure. Under thermal shock, BGA solder balls and multilayer ceramics are especially prone to cracking. Thermal cycling is another known cause of BGA solder fatigue failure, and it can also lead to wire bond fatigue failure within ICs.
Pressure-Sensitive Components
This is particularly critical for electronic equipment deployed in high vacuum or high-pressure environments. For example, electronic devices in underwater ROVs must undergo rigorous testing to ensure they won't fail under high-pressure conditions. Sealed ICs, electrolytic capacitors, powdered ferrites, and other components with air gaps should not be used in high-pressure environments as they may implode.
Protecting Your Circuit and Board Components
No specific component is inherently more prone to random failure. Instead, certain conditions that a system encounters make some components more susceptible to failure. Some failure causes encountered during a device's lifecycle, such as electrostatic discharge (ESD) or thermal stress, can be anticipated to ensure maximum reliability. Since many of these failures depend on selecting the right components, here are some guidelines to help you choose the most reliable components for your design:
Components for Surge Protection
Components for Accurate Power Regulation
High-Voltage/High-Power Passive Components
If you're unsure whether your components are prone to common failures, don't take chances with your design. Instead, you can search for the parts you need in Perceptive, including pricing, stock information, specifications, and datasheets.
