A controller works correctly for years, until suddenly the line stops without any clear reason. After a restart, everything returns to normal. After a few weeks, the situation repeats. There are no clear errors in the logs, measurements are correct, and the program has not been changed.
Such scenarios are well-known to maintenance departments. Sporadic restarts, random alarms, unstable communication, or unjustified line stoppages are very often attributed to power disturbances, the operating environment, or aging electronics.
In reality, one of the causes can be a phenomenon almost invisible to the naked eye,
yet capable of shutting down an entire production. These are tin whiskers.
What is the phenomenon of tin whiskers?
Tin whiskers are microscopic crystalline structures that grow from the surface of tin-coated components. They appear as thin metallic filaments that can reach a length of several millimeters with a diameter of a few micrometers. They form spontaneously on the surface of soldered joints, component leads, and electrical connectors. Importantly, they do not require the presence of voltage or current flow. Their growth process occurs during the operation of devices and can last for months or years without visible symptoms.
This means that in functional and stably operating electronics, a mechanism can develop that leads to sudden failure without prior warning signals.
How do tin whiskers form?
The main cause of tin whisker formation is mechanical stress within the tin layer. These stresses arise during manufacturing processes, material aging, and temperature changes. The metal structure strives to reduce stress, and one way to relieve it is the growth of individual crystals in the form of thin filaments.
Several factors influence the development of this phenomenon. The quality of the tinning process and the structure of the metallic coating are of significant importance. The diffusion of metals between the substrate and the tin layer is also crucial. In devices operating in an industrial environment, temperature fluctuations, humidity, and mechanical vibrations play an additional role. Whiskers can develop in new devices as well as in systems that have been in operation for many years.
How does the phenomenon affect electronic systems?
Tin whiskers are conductive, posing a serious risk of electrical short circuits. They can connect adjacent traces on printed circuit boards, integrated circuit leads, or connector contacts. Such short circuits can be transient and unstable, making their detection significantly difficult. This results in random controller restarts, communication errors, or unjustified system alarms.
In industry, the consequences are particularly severe. Disruptions in the operation of PLC controllers, inverters, or input/output modules can lead to the shutdown of production lines or loss of process synchronization. The problem is that after disassembling the device, the tin whisker often breaks, and the physical cause of the failure ceases to exist. The electronics return to operation, and the source of the problem remains unknown. For maintenance departments, this means prolonged diagnostics and high costs of production downtime.
What symptoms might indicate the possible occurrence of the phenomenon?
Tin whiskers are rarely the first suspicion during failure analysis. However, it is worth considering them in the case of sporadic and difficult-to-reproduce problems. Characteristic symptoms include random disruptions in electronic operation, unstable communication between devices, and errors appearing without a clear logical or software reason. Often, after replacing a module with a new one, the problem disappears, but after some time, it reappears in another device of the same generation. Such situations are typical for aging electronics operating in industrial conditions for many years without modernization.
Preventive actions in production plants
Completely eliminating the phenomenon is not possible at the operational stage, but its effects can be limited. Fundamental importance lies in controlling the environmental conditions of electronic operation and protecting printed circuit boards from moisture and contamination. In many applications, an effective method is the use of protective coatings on PCBs, which limit the possibility of short circuits.
The electronics lifecycle management strategy is also important. Devices operating continuously for many years should be covered by a diagnostic plan, including inspections of control modules and assessment of their technical condition, before difficult-to-diagnose failures occur.
What is the importance of specialized diagnostics?
The phenomenon of tin whiskers requires experience in analyzing industrial electronics failures. Standard functional tests often do not reveal the problem, which is why advanced inspection methods and knowledge of component degradation mechanisms are necessary. In many cases, only a detailed microscopic analysis can confirm the actual cause of the failure.
For maintenance departments, this means the need to cooperate with specialized industrial electronics repair services. Early identification of risk helps avoid unplanned downtime and costly replacements of entire control systems.
If unexplained failures of controllers, I/O modules, or operator panels occur in the plant, it is worth considering an audit of industrial electronics and automation devices at PLE Service. Our team specializes in audits and repairs of industrial electronics and supports maintenance departments in identifying the causes of unstable device operation.
