Why do tin whiskers happen?
The exact cause of tin whisker growth is still not fully understood. It is known that a whisker grows from its base and that the tin around the base does not thin as the whisker grows. It seems that the energy for growth comes from microstrains present in the tin or from externally applied pressure.
Does Lead free solder cause tin whiskers?
Pb-free solders are almost always alloys of tin, silver, copper and/or antimony; never pure tin. During the initial Pb-free transisiton, the number of cited tin whisker cases grew because the Pb-free solder alloys stress a tin plating more than leaded solder, so whiskers were more likely to occur.
How do you grow tin whiskers?
Whiskers grow spontaneously without an applied electric field or moisture. Tin whiskers grow under ambient conditions, under reduced pressure and even in the vacuum. The spontaneous growth of whiskers is an irreversible process. Whiskers may be straight, kinked or hooked and their outer surfaces are usually striated.
What is the electrical resistance of a tin whisker 3mm?
The electrical resistance of a tin whisker 3mm (1/8″) long is about 50 ohms. Because of their current carrying ability and low electrical resistance, whiskers are a threat to electronic circuits. The ability of tin whiskers to cause electronic circuit problems was established in 1951.
Can tin whiskers cause electronic circuit problems?
The ability of tin whiskers to cause electronic circuit problems was established in 1951. Many sudden failures and intermittent problems were associated with tin whiskers because of their ability to short closely spaced electronic circuits.
How can we reduce the risk of tin whisker induced failures?
The following list provides some suggestions for reducing the risk of tin whisker induced failures. Avoid the use of PURE TIN plated components if possible. Utilization of procurement specifications that have clear restrictions against the use of pure tin plating is highly recommended.
What are the characteristics of tin whiskers?
What are the Commonly Reported Characteristics of Tin Whiskers? What are Tin Whiskers? Tin whiskers are electrically conductive, crystalline structures of tin that sometimes grow from surfaces where tin (especially electroplated tin) is used as a final finish.