Solder alloys have been widely used as the interconnecting material in electronic packaging and assemblies because they provide both electrical interconnection as well as mechanical support.Sn-Pb solders were first used about 2000 years ago for metal interconnections.Pb containing solders especially the eutectic or near eutectic Sn-Pb alloys has long been the predominant choice of the electronics industry due to its low melting temperature (around 183oC),better wetting behavior and mechanical properties. Despite of all these advantages the toxicity of heavy metallic element Pb has lead in recent decades to increasing efforts to restrict its use. Following the banning of Pb in paints, fuels and plumbing application throughout the majority of the world, otherwise it could be demonstrated to present a direct risk to human health and environment.
Science and engineering of soldering has taken a major change in direction ever since the legislation that mandates restriction of certain hazardous substances (RoHS) and the waste electrical and electronic equipment had been introduced by many countries. The first administrative region of the world to actively legislate against Pb use in electronics has been the European Union, which has introduced RoHS and WEEE directives. These directives target the electrical and electronic equipment and are designed respectively to outlaw many harmful substances from use and make the producers of electrical and electronic goods responsible for their safe disposal or recycling at the end of their lives.
As cited by Environmental Protection Agency (EPA) of US, Pb and Pb containing compounds is one of the top 17 chemicals causing greatest threat to human life and environment.1st July 2006 has been official...
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...o its poor wettability, reliability, strength, easy oxidation and microvoid formation. In order to overcome these drawbacks and to further enhance the properties of Sn-Zn lead free system small amount of alloying elements such as Bi, Cu, In, Ag, Al, Ga, Sb, Cr, Ni, Ge were added as suggested by many researchers.
It has been found that the addition of Bi to the eutectic composition of Sn-Zn lead free system has improved various soldering properties. Addition of Bi decreases the melting point of the system and improves the wettability of Sn-Zn solder on Cu substrate. The wetting area increases by 2 -10 wt% approximately on addition of Bi content. On addition of Bi the surface tension of the solder has been decreased which has enhanced its wettability. Similarly the mechanical properties of the Sn-Zn solder have been improved on Bi addition but up to a certain extent.
...hed in 1957 and i one critic said it was a “tour de force”. The cat in the hat became an animated film in 1971.
the king of the jungle in Walt Disney Pictures= animated The Lion King - people
The Classic Years, movies that were made during this time: “Snow White (1937), Cinderella (1950), Sleeping Beauty (1959), Alice in Wonderland (1951), Peter Pan (1953), 101 Dalmatians (1961).” (Amy M. Davis 2008) was describe as the binning years of Disney. The gender roles were typically for a male would be a tall, handsome and strong while the female, was the damsel in distress. When a female was shown, it would show her in a traditional role in doing house work, cleaning, and gardening, etc. The middle Era, Movies that were made during this time: “The Rescuers (1977), The Fox and the Hound (1981) and The Black Cauldron (1985).” (Amy M. Davis 2008) Took a deeper turn especially when Walt had past leaving Roy Disney to continue his work. The company started to go into debt and there were not many films that had been made. The women roles remained the same. Then there was The Eisner Era, the movies that were made during this time: Belle (1991), Mulan (1998), and Jane (1999).” Which was when Disney ramped up by creating more Disney films. Although, the turning point in these films in which allowing a leading female roles. When Walt Disney past away, Disney (the business) started to change with the times in allowing female have leading roles and releasing them to the public. During this time, Disney allow women to become dependent unlike the women from the Classic
Soniak, Matt. “The Life and Times of the MGM Lion.” Mental Floss, 21 Oct. 2012. Web. 24 Feb. 2014. .
in the twenties when a man by the name of Walt "Elias" Disney (1901-66) a
Unfortunately, PCBs are hazardous to human and animal health, as well as to the environment. In studies published by the Agency for Toxic Substances and Disease Registry (ATSDR), the following health concerns are related to the ingestion of PCB's in people:
"Q&A WITH THE DIRECTORS OF DISNEY'S THE LION KING!" Interview by Victor Medina. Q&A WITH THE
Evidence provided to support these claims of human and wildlife harm is largely from laboratory studies in which large doses are fed to test animals, usually rats or mice, and field studies of wildlife species that have been exposed to the chemicals mentioned above. In laboratory studies, high doses are required to give weak hormone activity. These doses are not likely to be encountered in the environment. However the process of bioaccumulation can result in top-level predators such as humans to have contaminants at levels many million times greater than the environmental background levels (Guilette 1994). In field studies, toxicity caused by endocrine disruption has been associated with the presence of certain pollutants. Findings from such studies include: reproductive disruption in starfish due to PCBs, bird eggshell thinning due to DDT, reproductive failure in mink, small penises in alligators due to DDT and dicofol (Guillette 1994, Colburn et al 1996). In addition, a variety of reproductive problems in many other species are claimed to be associated with environmental contamination although the specific causative agents have not been determined. One recent discovery that complicates the situation is that there are many naturally occurring "phytoestrogens", or chemicals of plant origin that exhibit weak estrogenic properties.
Stainless steel, especially, Austenitic stainless steel, because of their high corrosion resistance and customizable mechanical properties has become an indispensable part of the regularly evolving modern day technology. Stainless steels of various grades find applications in numerous fields starting from the household to the nuclear reactors; from food and beverage cans to construction of different automobile parts. The formation of impervious oxide layer on the surface makes it suitable for use in adverse environments such as sea water.
I thought that the Lion King was a very good film to watch for all
Disney was founded by Walt Disney and Roy O. Disney in 1923. Throughout the earliest years they stabilshed themselves as a leader in animation and live action media. Later on, they would also begin to include other forms of entertainment and theme parks.
Roman slaves extracted and prepared the lead, describes a disease among the slaves that was clearly lead poisoning. Because of their potential toxicity, lead water pipes are no longer being installed. The greatest single use of lead metal today is in the plates of storage batteries for automobiles. The protective oxidation layer formed by lead in contact with such substances as air, sulfuric acid, and fluorine makes it highly resistant to corrosion. For this reason, lead has been used to make drainage pipes and lead chambers in sulfuric acid factories.
Beauty and the Beast is a Disney movie that debuted in 1991. When it first came out, the idea of the beautiful girl falling in love with a man because of what is inside of him was not a new concept. Inner beauty a...
GMAW (Gas Metal Arc Welding) is more economic; Springer reports that “ GMAW is an economic process because it has higher speeds and higher deposition rates than manual arc welding. There is also no need to constantly change electrodes” ( Page 11). GMAW has a higher speed, which means that you can get the job done faster. It also has high deposition rates which makes the weld look clean and smooth.” This method can be used for a high range of work, but it is not suited for repair work because of it’s weld quality” (Page 4). This process can be used for many variations of work including root welds, joints, T’s, butts, laps, and many more applications. Even though its used for many practices, it is not recommended to use this method for repair work because of the quality of the welds. “ It’s easy to use and it is inexpensive to afford now with 110v machines. But you cannot weld for a long time like a 220v machines would produce. Both have different duty cycles” (Parag. 7). M.I.G is something anyone can learn easily, it’s inexpensive to afford. 110v machines don't bring out the best power to weld, because these machines do not have a good duty cycle. Most people prefer 220v machines because they produce more work, even if they are more expensive. GMAW is the cheapest most reliable process for welding.
Bisphenol A (BPA) is a chemical compound used to create polycarbonate plastic and epoxy resins. Polycarbonate plastics are found in a wide range of products, but food and drink containers are the most concerning. Most people fear that BPA will have negative effect...