Full Answer
What are Tain whiskers?
Tin whiskers are metal filaments which grow from tin. They are extremely thin, 1-2uM typically, and grow as straight, kinked, or spiraled single crystals of tin.
What is a tin whisker made of?
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. Tin whiskers have been observed to grow to lengths of several millimeters (mm) and in rare instances to lengths in excess of 10 mm.
What is the resistance of a tin whisker?
Tin whiskers are metal filaments which grow from tin. They are extremely thin, 1-2uM typically, and grow as straight, kinked, or spiraled single crystals of tin. They can reach a length of 9mm (3/8") and carry 10mA of current before burning up. The electrical resistance of a tin whisker 3mm (1/8") long is about 50 ohms.
What makes tin whiskers so dangerous?
Whichever theory you agree with for the cause of tin whiskers, what makes them so dangerous is that after tin plating is stressed, tin whiskers can actually grow.
What is tin whiskering?
How long is a tin whisker?
What would have prevented tin whisker growth?
Why are whiskers dangerous?
How can investigators help prevent tin whiskers?
How to control whisker growth?
What is reflow tin?
See 4 more
About this website
How do you prevent tin whiskers?
Testing is the key to preventing tin whiskers. Testing for material composition and/or material structure should be part of any critical device manufacturing. Testing must be performed independent of the vendor.
What is meant by tin whiskers?
Tin whiskers (also called Sn whiskers or metal whiskers) are microscopic, conductive, hair-like crystals that emanate spontaneously from pure tin (especially electroplated tin) surfaces. Whiskers form primarily on elemental metals, but have also been found on alloys.
Are tin whiskers still a problem?
Although some experimenters have reported whisker growth from tin-lead alloys, such whiskers have also been reported to be dramatically smaller than those from pure tin plated surfaces and are believed to sufficiently small so as not to pose a significant risk for the geometries of today's microelectronics.
What are tin whiskers and why are they a hazard to space travel?
This may resemble an alien landscape, but it is actually a microscopic view of tin used to solder electronic components. The long shard rising from the surface is a 'tin whisker' – a spontaneous outgrowth representing a clear and present danger to space missions.
Why is it called whisker?
- Originally the word for a bundle of feathers, twigs, etc. used for whisking (from "whisk"), it then came to denote the projecting hairs or bristles of mammals.
Why do they call them whiskers?
Instead, objects that brush up against a whisker cause it to vibrate, which then stimulates the nerves in the hair follicle. This explains why the scientific name for whiskers is vibrissae, which derives from the Latin word, vibrio, meaning “to vibrate.”
How long does it take for tin whiskers to form?
They can grow fairly rapidly; incubation can range from days to years, according to the NASA backgrounder on whiskers. ¹ There is no set timetable for when they commence growing. A scanning electronic microscope (SEM) photograph of a needle-like tin whisker is shown in Figure 1.
Are whiskers necessary?
They serve an important function. Whiskers are specifically tuned sensory equipment that guide a cat through daily functions. These specialized hairs aid vision and help a cat navigate his environment, providing additional sensory input, much like antennae on insects.
What does whisker stress look like?
Those who uphold the concept of whisker stress point to the following signs: Pacing in front of a food or water bowl. Acting hungry, but doesn't want to eat from a bowl. Pawing food out of a bowl and eating it on the floor.
At what temperature does tin disintegrate?
The allotropic transformation At 13.2 degrees Celsius (about 56 degrees Fahrenheit) and below, pure tin transforms from the (silvery, ductile) allotrope of β-modification white tin to brittle, α-modification grey tin. Eventually it decomposes into powder, hence the name tin pest.
Why can't NASA take a bird into space?
Birds cannot fly in the vacuum of space because there is no air, but some birds have been brought to live on space stations before. American astronauts brought 32 chicken embryos to space on the Discovery STS-29 flight.
What are 5 hazards of sending humans to space?
5 Hazards of Human SpaceflightRadiation. ... Isolation and confinement. ... Distance from Earth. ... Gravity (or lack thereof) ... Hostile/closed environments. ... Human research essential to space exploration.
What does whiskers mean in welding?
Whiskers. Whiskers are short lengths of electrode wire sticking through the weld on the root side of the joint. They are caused by pushing the electrode wire past the leading edge of the weld pool. Whiskers can be prevented by: (1) Reducing the wire-feed speed and the speed of travel.
What does a tin mean in slang?
Slang. a small quantity of an illicit drug, especially from two to five grams of cocaine: usually sold in a small plastic bag, a glassine envelope, or often a small tin container.
What are whiskers in materials?
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.
What type of hair is a whisker?
Whisker hair is short, curly, dark hair that grows anterior to, above, and behind the ears in young persons who eventually develop severe androgenic alopecia. It is called whisker hair by lay persons because of its proximity and similarity to beard hair.
Mitigation Strategies for Tin Whiskers - UMD
Release 1.0 – Initial Created on 7/3/02 Updated: 8/28/02 Mitigation Strategies for Tin Whiskers Prepared by M. Osterman CALCE-EPSC Outline
STRATEGIES TO MITIGATE THE TIN WHISKER PHENOMENON - Vicor Corporation
Vicor Corp. Tel: 800-735-6200, 978-470-2900 Fax: 978-475-6715 Strategies to Mitigate the Tin Whisker Phenomenon Rev. 1.1 Page 3 of 4 Using its scanning electron microscope, Vicor has the ability to examine grain size on incoming lots. Bright Sn @ ambient Compressed matte Sn in 85/85 Compressed matte Sn
What is a whisker of tin?
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. Tin whiskers have been observed to grow to lengths of several millimeters (mm) and in rare instances to lengths in excess of 10 mm.
How many tin whiskers have been reported?
To date, there are reports of at least three tin whisker induced short circuits that resulted in complete failure of on-orbit commercial satellites .
Why do whiskers bend?
GSFC has demonstrated that whiskers can bend due to the forces of electrostatic attraction thus increasing the likelihood of tin whisker shorts ( ref. to GSFC experiment #4 ). Whisker Prone Processes : There is tremendous debate in the industry regarding which plating processes are prone to whisker formation.
Why do tin platings have residual stresses?
Residual stresses within the tin plating caused by factors such as the plating chemistry and process. Electroplated finishes (especially "bright" finishes) appear to be most susceptible to whisker formation reportedly because bright tin plating processes can introduce greater residual stresses than other plating processes.
Why do tin whiskers grow?
Some theories suggest that tin whiskers may grow in response to a mechanism of stress relief (especially "compressive" stress) within the tin plating.
How long is a whisker?
Whisker Length: Whiskers as long as a few millimeters are not uncommon with some experimenters observing whiskers in excess of 10 mm (400 mils) in length. Only a few researchers have measured the distribution of whisker lengths for specific specimens.
What are some examples of whiskers?
Other examples of metals that may form whiskers include some tin alloys, zinc, cadmium, indium, antimony, silver among others . People sometimes confuse the term "whiskers" with a more familiar phenomenon known as "dendrites" commonly formed by electrochemical migration processes.
What are tin whiskers?
Tin whiskers are electrically conductive, single crystal eruptions that can grow from surfaces where tin is deposited on a substrate surface (Fig. 1). High aspect ratio Sn whiskers are typically 1-5 µm in diameter and between 1-500 µm in length. They present reliability problems for the electronics industry with ongoing reports of tin whisker induced failures, particularly in the satellite and defense sectors (Fig. 2). Further, the current worldwide initiative to reduce the use of lead (Pb) is driving the electronics industry to consider high tin alternatives to the widely used Sn-37Pb alloys used for plating and solder. Continuing reports of tin whisker induced failures coupled with the lack of an industry-accepted understanding of tin whisker growth and/or test methods to identify whisker-prone products has made blanket acceptance of pure tin plating a risky proposition for high reliability systems. Harsh environments may exacerbate the problem by causing thermal and/or mechanical stresses in tin coated surfaces, leading to the growth of tin whiskers and to tin whisker induced failures. A common failure mode for whisker-prone electronic systems is whisker bridging, which causes electrical shorts (Fig. 3-4).
What is the role of humidity in whisker production?
Currently, we are investigating the role of calibrated, controlled humidity on whisker production and the role of electric fields in the whiskering process. Humidity is important due to the preponderance of studies which report enhanced whisker growth in the presence of oxygen. Further, in the cracked oxide theory of whisker growth, sufficient compressive stress is presumed to occur at positions of oxide weakness which are the locations of whisker emission. A unique viewpoint of the whisker surface oxide is afforded by in-situ, real-time scanning electron microscopy (SEM) observations of Sn whiskers during heating to temperatures greater than the melting point of Sn. As the Sn melts, the whiskers buckle, curl, and drain of liquid Sn, leaving behind a thin, solid, emptied tube of tin oxide with its higher melting point. With further electron-beam heating, the tin oxide tube frequently forms a coagulated spherical ball of material which is the final resting place of the dead whisker skeleton.
Is tin whisker growth mechanical?
While tin whisker growth is believed to be largely mechanical, there is currently no general agreement on the mechanism governing the growth of tin whiskers.
Why does vaping marijuana cause a lot of leaching?
Vaping marijuana raises the risk of this leaching, because the devices must be heated to much higher temperatures to aerosolize THC than to aerosolize nicotine. Previous research has shown that a greater amount of toxic substances are released as the voltage needed to heat vape devices increases.
How old is the woman who vapes?
A case report published Wednesday in the European Respiratory Journal describes a 49-year-old California woman who had symptoms now known to be associated with the more than 2,000 cases of vaping illnesses nationwide: shortness of breath, coughing and wheezing.
What metals are in e-liquid?
When the doctors tested the e-liquid left in the device, they found several metals: nickel, aluminum, manganese, lead, cobalt and chromium.
Does Zenpen come with prefilled cartridges?
What she did have was the ZenPen brand vape pen she'd been using for six months prior to getting sick. ZenPens do not come with pre-filled cartridges, so users must purchase their e-liquid elsewhere. ZenPen did not respond to NBC News' request for comment.
Can vaping damage your lungs?
The illness is usually only seen in industrial metal workers. Doctors have discovered yet another way that vaping — and vaping THC, in particular — can damage the lungs: when the metal coils of electronic cigarettes heat up to turn e-liquids into aerosols, toxic metals can leach into the liquid, leading to a rare condition usually only seen in ...
How does vaping work?
Unlike traditional smoking, vaping works by heating liquids that contain nicotine.
What is in e-liquid?
The team found that e-liquid exposed to heating coils produced a vapor containing significant amounts of chromium, lead, manganese, nickel and zinc. Highly toxic arsenic was also found in both the e-liquid and the heated vapor among a subset of 10 vapers, though how that metal got into the unheated e-liquid remains unclear.
How many vapers were recruited to the Hopkins study?
In the Hopkins study, published Feb. 21 in the journal Environmental Health Perspectives, investigators recruited 56 vapers in the Baltimore area to see whether the heating process introduces toxins into what is inhaled. The researchers used the vapers' own e-cigarette devices when examining the chemical content of e-liquid, vapor and residue.
What device did the researchers use to examine the chemical content of e-liquid, vapor and residue?
The researchers used the vapers' own e-cigarette devices when examining the chemical content of e-liquid, vapor and residue.
Do new coils produce more toxins?
The team also noted that toxic metal levels seemed to be higher among vapers who changed their heating coils more often, suggesting that new coils may produce more toxins than older ones.
Does vaping put you at risk?
Vaping manufacturers knowingly put you at risk.
Is vaping a safe alternative to smoking?
Toxic Metals Found in E-Cigarette Vapor. MONDAY, Feb. 26, 2018 (HealthDay News) -- If you think that "vaping" is a safe alternative to smoking, new research suggests you might be inadvertently inhaling unsafe levels of toxic metals. Scientists say the tiny metal coils that heat the liquid nitrogen in e-cigarettes may contaminate ...
What is a toxic metal found in cigarettes?
Cadmium – a toxic metal found in traditional cigarettes that causes breathing problems and disease
What happens when e-liquid heats up?
Additionally, when the e-liquid heats up, more toxic chemicals are formed. Because the Food and Drug Administration (FDA) has not begun its review of any e-cigarette or its ingredients, nor has FDA issued any standards on the products, e-cigarette composition and effects vary. What researchers do know is that these toxic chemicals ...
What is the chemical used to kill weeds?
Diacetyl – a chemical linked to a lung disease called bronchiolitis obliterans aka " popcorn lung ". Diethylene glycol – a toxic chemical used in antifreeze that is linked to lung disease.
What are the effects of e-cigarettes?
Because the Food and Drug Administration (FDA) has not begun its review of any e-cigarette or its ingredients, nor has FDA issued any standards on the products, e-cigarette composition and effects vary. What researchers do know is that these toxic chemicals and metals have all been found in e-cigarettes: 1 Nicotine – a highly addictive substance that negatively affects adolescent brain development 2 Propylene glycol – a common additive in food; also used to make things like antifreeze, paint solvent, and artificial smoke in fog machines 3 Carcinogens- chemicals known to cause cancer, including acetaldehyde and formaldehyde 4 Acrolein – a herbicide primarily used to kill weeds, can cause irreversible lung damage 5 Diacetyl – a chemical linked to a lung disease called bronchiolitis obliterans aka " popcorn lung " 6 Diethylene glycol – a toxic chemical used in antifreeze that is linked to lung disease 7 Heavy metals such as nickel, tin, lead 8 Cadmium – a toxic metal found in traditional cigarettes that causes breathing problems and disease 9 Benzene – a volatile organic compound (VOC) found in car exhaust 10 Ultrafine particles that can be inhaled deep into the lungs
Does e-juice contain nicotine?
The "e-juice" that fills the cartridges usually contains nicotine (which is extracted from tobacco), propylene glycol, flavorings and other chemicals. Studies have found that even e-cigarettes claiming to be nicotine-free contain trace amounts of nicotine.
What Causes Tin Whiskers?
A standard theory is that tin whiskers may occur when stress is exerted on the tin plating of an electronic device. Experts that agree with this theory have drilled down into the issue to spell out some factors that can cause stress on tin plating, such as:
Why are tin whiskers invisible?
Because of tin whiskers, as much as they can plague our PCB designs and destroy them, are also almost invisible to the human eye, being up to 100 times thinner than a single strand of human hair in some instances. Check it out below.
Why are tin whiskers dangerous?
Whichever theory you agree with for the cause of tin whiskers, what makes them so dangerous is that after tin plating is stressed, tin whiskers can actually grow. This isn’t just a static object; it’s something that can lay dormant and unseen on day one after manufacturing and a year down the road you’re board is completely ruined when tin whiskers are all over the place.
What happens when whiskers grow on a transistor?
( Image source) When whiskers do grow, they’ll usually follow a path between two conductors where the whisker will fuse, creating a short circuit between a path or producing a false signal and device failure.
What causes stress on tin plating?
These are stress factors that are due to the manufacturing process and plating chemistry.
Can whiskers be used to bridge leads?
Despite their almost invisible footprint, tin whiskers can create a bridge between the leads on electronic devices. And if you know anything about bridging, it’s that a short circuit is close behind, ready to ruin your device. While the issue of tin whiskers isn’t new, we had a relatively decent solution to them since the 1940s by using lead in our plating finishes and solder, but now we don’t, and so the problem of tin whiskers has come back into the spotlight.
Can tin whiskers be predicted?
The real issue with tin whiskers is that it’s completely random when or if they will infiltrate your circuit board. We can’t predict their patterns , and there are no quantitative data available that shows when a tin whisker might happen, it just does.
Why is bismuth used in whisker?
All the alloys containing bismuth were low whisker producers, presumably because it refines the grain structure of the metal. But, like silver, there is a threshold where too much becomes detrimental to overall performance.
Why did the high temperature and humidity conditions cause so much whisker growth?
Why did the high temperature and humidity conditions cause so much whisker growth? We speculated that the environment caused corrosion, which may have accelerated recrystallization and changes to the grain structure, and influenced intermetallic growth kinetics. The addition of bismuth to the solder alloys refines the grain structure. FIGURE 2 compares the microstructure of the low-whiskering Sn0.6Ag0.6Cu3Bi with the high-whiskering SAC305.
Is silver a whisker?
Elementally, we found that despite silver being a major contributor to whisker growth, it is absolutely necessary to promote wetting. While 3% seems a little high based on SAC 305’s abominable whiskering performance, how much is enough and how much is too much? We found 0.6% to be the threshold where the propensity for whisker propagation outweighs the benefit of faster wetting speeds and higher wetting angles.
Does bismuth affect tin whiskers?
Silver is a known whisker promoter but small amounts of bismuth mitigate the problem. Alloy composition has a strong influence on tin whisker production and has proven to either mitigate or exacerbate the propensity for a solder to whisker. In our year-long study of the relationship between alloy composition on tin whisker formation, SAC 305 notoriously produced more and larger whiskers than any of the other alloys tested.
Where do stress whiskers travel?
When they run out of boundaries, they eject whiskers. They can travel for a long time on internal grain boundaries before “surfacing.” This phenomenon is similar to that of the recent seismic activity in Oklahoma, where the stresses induced by high-pressure wastewater injection travel though the earth’s crust and manifest themselves as earthquakes up to 20 miles away from the injection site. Because the stresses travel so far, and at rates that vary due to the medium through which they are traveling, it is nearly impossible to pinpoint their original location.
Does thermal aging cause whiskers?
The environmental influence on whisker production was very interesting. Much to our surprise, neither thermal cycling nor intermetallic growth due to thermal aging showed direct, significant correlations to whisker generation , but high temperature and humidity storage did. Prior to these tests, it was widely believed that the repeated expansion and contraction of thermal cycling would induce stresses that would result in whiskers, but after 1000 cycles of -40° to 85°C, no whiskers were found. Likewise, the stresses induced by the intermetallic growth of thermal aging were expected to produce whiskers, but again, the data didn’t show it. We saw a trend where alloys that produced smaller intermetallics also produced fewer whiskers, but only one of the nine alloys analyzed showed a definite statistical relationship.
Is Pb free solder good for whiskers?
There will inevitably be a number of Pb-free solder alloy combinations that demonstrate superior performance in mitigating tin whiskers, but none will be without compromises. Enhancing one property in a material almost always comes at the cost of sacrificing a bit of another. If the proper balance of reliability, processability, manufacturability and recyclability can be struck while successfully suppressing tin whisker formation, the commercial potential for such a solder alloy is tremendous.
What is tin whiskering?
Recently, a little-known phenomenon called tin whiskering caused the recall of several models of a pacemaker. This incident revealed tin whiskers to be a general threat to all users and manufacturers of medical devices that incorporate electronic circuitry. To prevent future problems, field personnel will need to educate themselves ...
How long is a tin whisker?
They can reach a length of 9mm (3/8") and carry 10mA of current before burning up. The electrical resistance of a tin whisker 3mm (1/8") long is about 50 ohms.
What would have prevented tin whisker growth?
Examination of the manufacturing process revealed that the manufacturer's specification for the crystal component should have prevented tin-whisker growth. The crystal component specification called for gold, nickel, or solder plating. Any one of these case coatings would have prevented the tin whisker problem.
Why are whiskers dangerous?
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.
How can investigators help prevent tin whiskers?
The investigator can help prevent tin whisker problems by enquiring into material testing of critical electronic components. However, knowledge of tin whiskers is new in the industry. The investigator may first have to educate manufacturers about tin whisker problems before looking into material testing.
How to control whisker growth?
The most common is to avoid using tin. Other metals or alloys of tin are used instead with solder (tin/lead) being the most popular. The other method is known as "reflow." After the tin is in place, the tin coated part is heated to a temperature above tin's melting point. This heating releases any stress that exists within the tin deposit.
What is reflow tin?
Other metals or alloys of tin are used instead with solder (tin/lead) being the most popular. The other method is known as "reflow.". After the tin is in place, the tin coated part is heated to a temperature above tin's melting point. This heating releases any stress that exists within the tin deposit.