Table of Contents
What causes tin whisker growth?
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.
Are tin whiskers still a problem?
An Overview of the Problem Tin whiskers are real. They are microscopic conductive fibers emanating from pure tin surfaces, and they pose a serious problem to electronics of all types. Tin whiskers are not a new phenomenon resulting from the switch to lead-free electronics.
How long does it take tin whiskers to grow?
Tin whiskers are almost invisible to the human eye and are 10 to 100 times thinner than a human hair (see figure 1). They can bridge fairly large distances between electrical device leads, and in so doing, can short out the conductors. They can grow fairly rapidly; incubation can range from days to years.
How do you remove tin whiskers?
The standard procedures are affectionately called strip and dip. Basically a chemical or a metallurgical process is used to remove the tin coating and replace it with a tin lead coating. Some use chemistry and acids to strip the tin off and then usually they dip it to replace it.
What is tin whisker mitigation?
The most obvious mitigation strategy for removing the threat of tin whiskers is to avoid parts with pure tin finishes and to be vigilant in reviewing parts received, in particular from companies that provide the same parts with pure tin finishes.
What causes metal whiskers?
Metal whiskering is a phenomenon which occurs in electrical devices when metals form long whisker-like projections over time. It was noticed that small metal hairs or tendrils grew between metal solder pads causing short circuits. Metal whiskers form in the presence of compressive stress.
Does conformal coating prevent tin whiskers?
After more than two years of experimentation, we have found that conformal coat does not prevent tin whisker formation although it does appear to substantially reduce the rate of growth. Especially for long duration missions, use of conformal coat as a sole means of risk mitigation may not be completely effective.
What are zinc whiskers?
Zinc whiskers are crystals that form on the surfaces of steel items that have been electroplated with zinc. They can form on any zinc electroplated metal surface. For data centers, this can mean the plenum sides of raised floor tiles, pedestals, stringers, cable and runway trays and other infrastructural supports.
What is whisker material?
A whisker is a thin strand of metal that grows out of the original shape of the metal. A whisker can form only on some metals and metal alloys. It is thought that whiskers are created by residual stresses in the metal; however, the exact mechanism that causes whisker formation is not well understood.
How do you prevent zinc whiskers?
What are Zinc Whiskers and How Can You Prevent Them?
- Consider using raised floor tiles that don’t rely on zinc coating.
- Consider products that offer a hot-dip galvanized zinc coating – the hot-dip includes an extra layer of coating that puts the zinc under much less pressure than that of electroplating.
How do zinc whiskers form?
To relieve the pressure, the zinc may expand outwards, which forms microscopic filaments on the outer surface of these plates. These filaments grow over time, resulting in whiskers you can just barely observe with the naked eye.
What is the difference between fiber and whisker?
Fiber is a material consisting of long chain of molecule having thread like structure. Whiskers are produced by crystallizing the material on small scale.
What are solder whiskers?
Whisker (metallurgy) Metal whiskering is a phenomenon which occurs in electrical devices when metals form long whisker-like projections over time. Tin whiskers were noticed and documented in the vacuum tube era of electronics early in the 20th century in equipment that used pure, or almost pure, tin solder in their production.
What are marking whiskers?
Survey Marking Whiskers. 6 inch Marking Whiskers are a practical marking choice for surveying and construction sites. They can also be used for marking utility lines and athletic fields. They are designed to provide maximum visibility and withstand multiple passes of a grader blade.
What are Tim whiskers?
Tin whiskers are individual crystals of tin that grow spontaneously from a tinned surface, usually as a result of stress of some sort. The phenomenon poses problems for manufacturers who would prefer using tin rather than lead for interconnections.
What is Old Whiskers?
One of those White House pets was Old Whiskers (or “His Whiskers,” according to some sources). Like most goats, Old Whiskers was a bit of an ornery fellow. One day, the goat apparently had had enough of pulling a cart and being poked and prodded by children.