Merck’s Risky Bet on Research Free Essays

While Kenneth Frazier worked liability suits for Merck, he caught the company’s attention and they hired him in 1992. By 1999 Frazier was appointed Merck’s general counsel. Merck saw that Frazier had several good personality traits and values that would benefit their organization. We will write a custom essay sample on Merck’s Risky Bet on Research or any similar topic only for you Order Now Kenneth Frazier is a very hard-working man and has been taught not to fail and to push himself to excellence. Frazier has always pushed himself to always do better, he has never just settled. Frazier likes to take risks to see how far he can push himself and to see what he can accomplish. Frazier has a very high self-esteem and a need for achievement. Under the five big personality traits, Frazier best fits under openness to experience. He is willing to take risks and is daring and open minded. I believe one of the most important terminal values to Frazier is a sense of accomplishment. Even though, there are several terminal values that I believe are important to Frazier, I feel this is the most important. Frazier lost his mother at a very young age and was raised by his hard-working father. His father taught him to work equally as hard and to always strive for excellence. Frazier believes that at work he should never back down and always strive for more, and that you must work hard to accomplish everything you want. This especially showed when Merck found their drug Vioxx was doubling the risk of heart attach and strokes and Frazier fought each case instead of taking the easy way out and negotiating settlements. Frazier won 11 of the 16 cases. Frazier was determined to win and he did. Frazier gets pleasure from achieving his goals and enjoys the social recognition that he gets by winning his cases. Instrumental values are just as important as terminal values. The most instrumental value that stands out in Frazier is his ambition. Frazier is not only hard working but understands what it takes to achieve his goals. A few of the other instrumental values that I feel are important to Frazier are being responsible, polite, and daring. Working as a litigator or in management you will not always be liked. At times people will go against you and not agree with what you are doing. Frazier is daring as he goes against others but when he must go against others he does it respectfully and politely so he can get others to take his side and agree with him. Frazier has some very important personality traits that will help him influence Merck’s culture in his role as CEO. Frazier’s openness to experience gives him the ability to have an open mind and the ability to take risk that will allow him to move the company forward. Frazier also has the ability as CEO to mentor other managers to achieve the company’s goals. After watching Frazier handle some of Merck’s liability suites, the company decided that Frazier would be a valuable asset. Merck could see that Frazier had some very important personality traits that could benefit their company. How to cite Merck’s Risky Bet on Research, Papers

Marketing Segmentation free essay sample

A relatively small firm should use market segmentation to find a  niche  in the marketplace because it is realistically impossible for a small firm to compete against a much bigger firm in marketing the similar product. For example, magine the difficulties in developing a new brand of cola and competing against Coke and Pepsi. So by finding a small niche in the marketplace, it’ll be a much more successful approach. For example, this is what Snapple and Tom’s Of Maine toothpaste did. `Market Segmentation and Targeting’ (Journal of Internet Commerce, 2007,  6(1), 83-99. `Weinstein(2004, 3) claimed that’ the overall purpose of using market segmentation is to improve a company’s competitive positon and better serve the needs of the customers. Other objectives of market segmentation includes increasing sales, improved market share and also to enhanced the image and reputation of the business. On top of that, market segmentation can also help businesses to Differentiate your products and services to meet your customer needs and desire, find hidden needs and make improvements to your existing products, Target your marketing mix to the customers most likely to ant your products or services,  Identify behaviors and buying motives for your products,  Identify your most and least profitable customers,   Help you avoid unprofitable markets and   Increase brand loyalty and decrease brand switching. `Market’ segmentation services’ (Goldberg, 2008). There is no single way segment a market. A marketer has to try to different segmentation variables , alone and in combination to find the best way to view the market structure. There are three type of variables that marketers look at when they segment the market. Variables such as geographic, demographic, pyschographic and behavioral variables. Geographic segmentations calls for dividing the market into different geographical units such as nations, regions, province, parishes, cities, or even neighborhoods. Depending on its budget, a company may decide to operate in one or a few geographical areas or to operate in all areas but pay attention to geographical differences in needs and wants. The other segmentation variable that marketers look at is demographic segmentation. Demographic segmentation is when company divides the market into groups based on variables such as age, gender, family size, family life cycle, income, occupation, education, religion, race, generation and nationality. These different criteria’s differentiates the needs and wants from each individual consumer. Other than that, companies also look at psychographic segmentation. Psychographic segmentation divides buyers into different group based on social class, lifestyle, or personality characteristics. Last but not least, behavioural segmentation divides consumers into group based on consumer knowledge, attitudes, uses, or the responses to a product. (Kotler and Armstrong 2010, 216). 2. 0 Target market identification. The primary target for this report would be Beyonce Giselle Knowless, known as Beyonce internationally. Beyonce is an actress, model and a renown ramp;b artist. Beyonce first started her recording career with 2 other female artist, Kelly Rowland and Michelle Williams in a group called `destiny child’ and later on went solo in the year 2000. As someone who is fond of fashion, Knowles combines its artistic elements with her music videos and performances; she uses different styles and tries to harmonize it with the music while performing. Beyonce is one of the most influential star icons in this century without a doubt. Just like many others, Beyonce divides her fans into groups based on demographic, geographic, psychographic and behavioural traits. 2. 1 Geographical traits Geographic segmentation is important for Beyonce and the line of work that she is in. Having said, the intended audience for a given product is divided according to geographic units, such as nations, states, regions, counties, cities, or neighborhoods to fit the needs of individual geographic areas, localizing the products, advertising, and sales effort to geographic differences in needs and wants. Marketers will also study the population density or regional climate as factors of geographic segmentation. This is why Beyonce only have her tours and concerts in specific states and not the entire country. When she had her 2009 tour in Australia, she only performed in several states such as Melbourne, Sydney, Adelaide and Perth. (Liveguide, 2009). 2. 2 Demographic Traits. The line of work that Beyonce is in, demographic segmentation will most probably be her priority in segmenting her customer groups. This is because consumer needs, wants and usage often vary closely with demographics variables. (Kotler and Armstrong 2010, 218). Majority of Beyonce’s target group are age from 17 – 34. Next, most of Beyonce targeted group are in high school, post graduates and graduates. Although Beyonce’s music is suitable for both male and female, however 54% of her fans are female and 46% are males. An estimated 54% of her fans have no children while the rest of the 46% has. In addition, Beyonce’s target market group consists of several nationalities. The majority of them are American- Africans while the rest are Asians, Australians and Americans. Majority of her fans are less affluent as compare to others because most of her fans are not at the age where they earn a lot of money or still studying. An estimated 33% of her fans earns between 30-60 thousand Usd per annum. Quantcast audience profile 2010) 2. 3 Psychographic Traits. Psychographic segmentation consists of traits such as social class, the lifestyle and personality. Relating to the primary target Beyonce, majority of her target group falls under the three category of the social class trait. Majority of them are in lower lowers, upper lowers and a minority of them are in the working class. M arketers often segment their markets by consumer lifestyles and base their marketing strategies on the lifestyles appeal. For Beyonce, majority of her target group are teenagers and pop lifestyle is the sort of lifestyle that Beyonce target. As for personality traits, due to the wide range of personality that this world has, Beyonce’s music usually targets female with a much sensitive and emotional personality. 2. 4 Behavioral Traits. Behavioral segmentation is about dividing buyers based on their knowledge, attitudes , uses and responses to a product. Markets can be also segmented into usage rates , readiness stage and overall attitude towards the brand. For Beyonce, this is a important trait to look at because by understanding this traits, Beyonce will then be able to produce songs and product that serves the needs and wants of the consumers. On top of that, Beyonce can then produce her products based on usage rates of her consumer, user status and loyalty status. By understanding these traits, it’ll help Beyonce save production cost and generate even more profit. 3. 0 Discussion/ rationale of the target market collage. The market place for Beyonce is massive because everything revolves around her industry which is media entertainments. The collage illustrates the target market group for Beyonce. It clearly shows the multidimensional approach that Beyonce has considered in segmenting the market for her business. With geographic segmentation, Beyonce has travel a lot of places to promote new release albums and to enhance her popularity. She has been almost all over Europe and in recent years, she had her tour in few of the major cities in Australia. States such as Melbourne, Sydney, Adelaide, and Perth to promote her â€Å"The Beyonce Experience Tour†. (liveguide, 2009). After having seen, it’s obvious that Beyonce’s popularity only exist in couple of the major states in Australia. However, by touring and performing live concerts will definitely enhanced her popularity in Australia. The majority of Beyonce fans are teenagers but there are adults that adore her as well. The age group that listens to Beyonce’s music starts from the tender age of 15. Most of Beyonce’s fans are female and only a handful of them are males. Beyonce music attracts all sorts of race and nationality in this world but the majority o her fan bases are American- Africans. As we know, Beyonce is world renowned `POP’ amp; `RnB’ musician, therefore the colors that she uses in her advertisements, the color of her dress in her videos and so on represents the approach and the image that she trying to give to society. Majority of Beyonce fans are teenagers that still adores dancing, mingling and partying. However, some of her fans relate their personal emotions and issues with Beyonce’s music. By knowing her targeted group, Beyonce generically write music that she knows her fans can and will listen too. With this knowledge and talent, Beyonce then concentrate in producing her music depending to wants and needs of the consumer in different times. For example, Beyonce would produce Christmas songs during Christmas season. The genre of Beyonce’s music also influence greatly on which market group she attracts and targets. Most of the consumers that listens and purchases her music are usually RnB , Pop, and sentimental song lovers. Because Beyonce is so influential with her looks and music, many people tends to follow the way she dresses and looks. With this, unlimited business potential arises for Beyonce. She has clothing lines that belongs to her, perfumes and many more product that majority of her target group which are females would purchase.

Heart Of Dark Essays - Joseph Conrad, Congo Free State,

Heart Of Dark In Joseph Conrad's book Heart of Darkness the Europeans are cut off from civilization, overtaken by greed, exploitation, and material interests from his own kind. Conrad develops themes of personal power, individual responsibility, and social justice. His book has all the trappings of the conventional adventure tale - mystery, exotic setting, escape, suspense, unexpected attack. The book is a record of things seen and done by Conrad while in the Belgian Congo. Conrad uses Marlow, the main character in the book, as a narrator so he himself can enter the story and tell it out of his own philosophical mind. Conrad's voyages to the Atlantic and Pacific, and the coasts of Seas of the East brought contrasts of novelty and exotic discovery. By the time Conrad took his harrowing journey into the Congo in 1890, reality had become unconditional. The African venture figured as his descent into hell. He returned ravaged by the illness and mental disruption which undermined his health for the rem aining years of his life. Marlow's journey into the Congo, like Conrad's journey, was also meaningful. Marlow experienced the violent threat of nature, the insensibility of reality, and the moral darkness. We have noticed that important motives in Heart of Darkness connect the white men with the Africans. Conrad knew that the white men who come to Africa professing to bring progress and light to darkest Africa have themselves been deprived of the sanctions of their European social orders; they also have been alienated from the old tribal ways. Thrown upon their own inner spiritual

broken spears essays

broken spears essays Around 1519, a Spaniard by the name of Hernan Cortes sailed to what we now know as modern day Mexico. Diego Velazques, governor of Cuba, instructed Cortes to make contact with the New World. What was supposed to be an innocent journey of exploration and trading, became a horrific genocide of the Aztecs of the New World. Cortes was a violent, manipulative, and a greedy man. To give you an idea of the violence Cortes and his men were capable of committing, I would like to relate a passage of a Nahautl account, from the book by Miguel Leon-Portilla, Broken Spears: They ran in among the dancers, forcing their way to where the drums played. They attacked the man who was drumming and cut off his arms. Then they cut off his head, and it rolled across the floor. They attacked all the celebrants, stabbing them, spearing them, striking them with their swords. They attacked some of the from behind, and these fell instantly to the ground with their entrails hanging out. Others they beheaded: they cut off their heads, or split their heads to pieces. They struck others in the shoulders, and their arms were torn from their bodies. They wounded some in the thigh and some in the calf. They slashed others in the abdomen, and their entrails all spilled to the ground. Some attempted to run away but their intestines dragged as they ran; they seemed to tangle their feet in their own entrails. (xxvi) The previous passage took place during the Fiesta of Toxcatl. Although Cortes was not present at this time, I believe the actions of his men were a direct reflection of Cortes thirst for violence. I also came across different parts in the book where it described how Cortes and the Spaniards would hang, torture, and feed people to their dogs. Cortes was also involved in the killing of unarmed people in Cholula. Cortes would use any means necessary to conquer the Aztecs and rob them of their gold. Cortes most likely was a viol ...

Poem To Elsie Essay Example | Topics and Well Written Essays - 1000 words

Poem To Elsie - Essay Example The diction is often general and seemingly flaccid; "devil-may-care men who have taken / to railroading / out of sheer lust of adventure," or "young slatterns, bathed / in filth." Its major focus is the speaker himself, who sums up in swift, passionate, and broken utterance the human condition in which he participates. (Axelrod, Roman, Travisano, 86-87) Along the texture of the development of the poem the gradual ascendancy evokes enlightened pastures when it says "some doctor's family, some Elsie/voluptuous water/expressing with broken/brain the truth about us/her great ungainly hips and flipping breasts/addressed to cheap /jewelry/and rich young men with fine eyes/ as if the earth under our feet/were/an excrement of some sky", the poem describes Elsie's body and alert us that the female body linked to the hierarchies of the country, the class and the gender in the culture. (Axelrod, Roman, Travisano, 86-87) Like most of William Carlos Williams's poems 'To Elsie' is revealed in a formation of translucent transparency which in retrospect is represented in the most punctual truthfulness to the point of honesty. In this context it should be remembered that the Williams poems are uniquely honest towards itself and they reveal everything that is possibly expressible though words. This honesty in words is deeply felt when Williams narrates in the last lines of the poem almost in a circumstantial detached mood. "It is only in isolate flecks that / something / is given off / No one / to witness / and adjust, no one to drive the car. (Axelrod, Roman, Travisano, 87) It is so evident in these lines that the poet is viewing the whole scenario as a circumspect manner with a mood of watching the whole expressions as a passive watcher. Going through the lines of the poem 'To Elisie' I was able to feel the pain of the poet is transmitted into the readers' mind through a contour of expressions expressed not only in an honest but in an extremely informative manner. This is because the poet is willing to take himself away from the present scenario as if as a mode of protest against the then present situation which was far from his socialist sense of utopia. (Matterson, 29) This formation of the poem and the way it builds up from a rather unemotional scenario into words describing the common plight as Americans, at least the America of his time reflects the psyche of the poet time and again throughout the poem with such line that says "as if the earth under our feet/were/an excrement of some sky". It could be found that these are the things which destroy the American dream of the poet's time. Until he can force his imagination to take account of and establish his contact with his own, local, instead of letting himself strain after the other where of "deer / going by fields of goldenrod," until such a time, the American is doomed to go crazy. (Axelrod, Roman, Travisano, 86-87) Structurally speaking, I felt the form is directly derived from the optimistic philosophy of the life itself thereby placing the entire poem in a simplistic format that blends flawlessly with the apparent simplicity of the poem. To me, theoretically, Williams's poems are placed in the other side of the coin that is used by the poets like T.S.

Great Depression Essay Example | Topics and Well Written Essays - 500 words

Great Depression - Essay Example Many dynamics factored into bringing about the Great Depression but there were two central contributing causes. The first of these was that the wealth of the nation was unevenly distributed. A middle class, as we would define it today, did not exist. The country was literally divided between the ‘haves and the have nots.’ Some very few people had enormous wealth and power while a much greater number of the population consisted of those struggling to pay the bills each month. This condition established an unstable economy requiring only a small thing to send it off the tracks. This condition then combined with inflated speculations among the majority of stock market investors much like what has occurred recently in the marketplace. â€Å"The excessive speculation in the late 1920’s kept the stock market artificially high, but eventually lead to large market crashes. These market crashes, combined with the mal-distribution of wealth, caused the American economy to capsize† (Hicks, 1960 p. 110). The effects of the Great Depression were many and widespread. Banks were not federally mandated to insure depositors at this time. Therefore when the hundreds of banks suddenly failed, millions of people lost their life savings. Immediately following the bank failures, many factories were forced to close and all types and sizes of businesses dissolved leaving many workers without jobs or money in the bank. Many businesses and financial institutions failed. The businesses that stayed open were barely making enough to remain operational. The tax base fell suddenly which affected local governments, many of which could not continue to conduct some city services at a normal capacity. The price of farm products also fell sharply and the mass foreclosures of family farms soon followed causing bloody clashes between the owners and the bank representatives. Of those who were able to hold on to

Effect Of Vibration On Solder Joint Reliability Engineering Essay

Effect Of Vibration On Solder Joint Reliability Engineering Essay CHAPTER 01 INTRODUCTION SOLDER JOINT IN ELECTRONIC ASSEMBLIES Circuit boards range from simple single moulded plastic boards with copper conductors on one or both sides to multilayer boards with copper conductors, each layer being separated by a dielectric and interconnected by metal conductors. Minimum line width and spacing between lines is less than 100  µm. The board typically is made from a composite such as an epoxy with layered sheets of woven fibreglass. The dielectric material between layers of conductors is usually a polymer, for example polyimide. To maintain solder ability, the exposed copper may be coated with an inhibitor such as benzotriazole or with a solder overcoat. Components are attached to the board with solder or metal-filled conductive adhesives. Fully assembled boards may be further protected against moisture, contamination, and mechanical damage by a cover coat. 1.2 SOLDER JOINT RELIABILITY AND FAILURE Solder joints are widely used in the electronic packaging industry to produce good electrical, thermal, and mechanical connections between the package and the printed circuit board. Eighty percentage of the mechanical failure in airborne and automation electronic caused by vibration and shock. Design appropriate measure to ensure the survival equipment in the shock and vibration environment is necessary to do so. Remaining 20 percentage of mechanical failure related to thermal stresses resulting from high thermal gradients, coefficient of thermal expansion and high coefficient of elasticity. Solder joint failure occur in several reasons: Poor design of the solder joint A bad solder joint treatment Solder material Excessive stress applied to solder joints. In general, however, the solder joint failure are simply ranked according to the ature of stress that have caused. Most joint failure fall into three major categories: Fatigue failure due to cyclic stress application Due to the implementation of a long term or permanent load The stress is due to overloading in the short term Reflow profile also has a significant role on solder joint reliablity. because It also has a high influence micro structure of the solder joint. Vibration failure of solder joints is often assessed for reliability using high accelerated life test, which is represented by a GRMS- time curve. For surface mount microelectronic components, an approximation of printed circuit board (PCB) model analysis can be made by assuming PCB as a bare unpopulated thin plate because the increase in stiffness of PCB due to the mounting of the components is approximately offset by the increase in total mass of the populated PCB [2]. However, this approximation can lead to errors in natural frequency prediction for different package profiles, for flip-chip-on-board (FCOB) and plastic-ball-grid-array (PBGA) assemblies [3,4]. When the component has small profile, the approximation of PCB assembly as a bare PCB can provide satisfactory modal analysis results because the stiffness and mass contribution of small component to PCB assembly is not significant. In this study, varying G-level random vibration tests for PCB assembly were conducted. In order to assess the reliability of PCB assembly, it is necessary to conduct the dynamic analysis. A global-local modeling approach [4-6] was used. The analyses by Basaran [7,8], Chandaroy [9] and Zhao et al. [10] show that solder joint deformation is in the elastic range for vibration loading. The global-local or submodeling method [11-13] has been used for the board level FE simulation. In this study, four different model cases were investigated for FEA modal analysis to calculate the first order natural frequency of the FCOB assembly. A quasi-static analysis approach was conducted for the FCOB assembly to evaluate the stress strain behavior of the solder joints. A harmonic analysis was also investigated to study the dynamic response of the FCOB assembly subjected to vibration load. Fatigue life prediction results from the quasi-static analysis and harmonic analysis approaches were compared to the test results. 1.3 PROJECT PURPOSE In this modern world due to the causes of health and environmental issues the electronic manufacturing industries facing a challenging problem of necessity to produce reliable solder products in very high density with very low cost. Solder joints are very important to the reliability of Printed Circuit Boards (PCB). This is a one of the leading factor in transmission of electrical and thermal connections. In case of every PCB even a smaller solder joints are very important. So this project investigates the Effect of Vibration on Solder Joint Reliability in Electronics Assembly Applications. Solder joint of a Electronic assembly is very important measurement because of This model based study might help engineers effectively improve the PCB mechanical design and thus improve reliability of electronics attached to the PCB by considering realistic uncertainties and adverse vibration environments. CHAPTER 02 LITERATURE REVIEW 2.1 SINE ON RANDOM VIBRATION TESTING Vibration sine on random testing is performed by superimposing a sine wave on top of a random environment. A sine on random vibration test duplicates the combined environment of a spinning helicopter blade with its distinct resonant levels and the rest of the aircraft which generates random engine and aerodynamic induced vibration. Gunfire on board an aircraft causes sine vibration while the rest of the aircraft generates random excitations. These types of tests are duplicating vibration characterized by dominant peaks (sinusoids) superimposed on a broadband background Another variation would be a swept sine on random test. 2.2 SINUSOIDAL VIBRATION TESTING Dynamic deflections of materials caused by vibration can cause a host of problems and malfunctions including failed electrical components, deformed seals, optical and mechanical misalignment, cracked or broken structures, excessive electrical noise, electrical shorts, chafed wiring. Because sine vibration is basically a certain fundamental frequency and the harmonics of that fundamental, in its pure state, this type of vibration is generated by a limited but significant number of sources. Expressed as amplitude versus frequency, sine vibration is the type of vibration generated in the field by sources such as engine rotational speeds, propeller and turbine blade passage frequencies, rotor blade passage and launch vehicles. While much of real world vibration is random, sine vibration testing accomplishes several important goals in product qualification and testing. Much material and finished product was modeled on some type of sine vibe signature. A sine sweep of frequencies will determine whether the assumptions were correct and if the deviations are significant enough to cause design changes. In other words, sweep will establish if the anticipated frequency has been met and/or discovers the test item fundamental frequency. Similarly, a sweep will help identify the test subject resonance frequencies, which may be the points at which the item experiences particularly stressful deflections. By dwelling at those frequencies in subsequent tests, premature failures due to the properties of the material may come to light before the items sees field use. Some of the following tests include fixed frequency at higher levels of the controlling variable (displacement, velocity, acceleration), and random vibration . Per customer request, NTS will run sweeps in one direction, decreasing, increasing or bi-directionally and can change frequency logarithmically or linearly. Another typical sinusoidal vibration test, sine burst such as the teardrop, goes rapidly to peak pulse and then decays at lower rate (to prevent damage to the unit). The burst test puts a maximum load into an article at a rapid rate and particularly stresses joints and seams to identify workmanship and design issues. 2.3RANDOM VIBRATION TESTING The legitimacy of random vibration s an effective tool of screening work man ship defects came about during manufacturing. Up until that limited hertz sine was applied during reliability testing. Pure sinusoidal vibration is composed of a single frequency at any given time. Comparisons tests revealed that to equal the effectiveness of random vibration. The test item will have to be subjected to many sine frequencies over a longer period of time, and may unintentionally fatigue the test item. Random vibrations undercover defect faster. 2.4 Real world simulation. Most vibration in real world is random for example a vehicle travelling over road experience random vibration from the road irregularities. A ground launched rocket vehicle experiences non stationary vibration during its flight the motor ignites the rocket travel through the atmosphere , the motor burn ends and so forth even in wing when subjected to turbulent air flow, undergoes random vibration. Random vibration is composed of multitude of continues spectrum of frequencies. Motion varies randomly with time. It can be presented in the domain by a power spectral density function [G2/Hz]. HIGHLY-ACCELERATED LIFE TESTING (HALT) Exposes the product to a step-by-step cycling in environmental variables such as temperature, shock and vibration. HALT involves vibration testing in all three axes using a random mode of frequencies. Finally, HALT testing can include the simultaneous cycling of multiple environmental variables, for example, temperature cycling plus vibration testing. This multi-variable testing approach provides a closer approximation of real-world operating environments. Unlike conventional testing, the goal of HALT testing is to break the product. When the product fails, the weakest link is identified, so engineers know exactly what needs to be done to improve product quality. After a product has failed, the weak component(s) are upgraded or reinforced. The revised product is then subjected to another round of HALT testing, with the range of temperature, vibration, or shock further increased, so the product fails again. This identifies the next weakest link. By going through several iterations like this, the product can be made quite robust. With this informed approach, only the weak spots are identified for improvement. This type of testing provides so much information about the construction and performance of a product, that it can bequite helpful for newer engineers assigned to a product with which they are not completely familiar. HALT testing must be performed during the design phase of a product to make sure the basic design is reliable. But it is important to note that the units being tested are likely to be hand-made engineering prototypes. At Trace, we have found that HALT testing should also be performed on actual production units, to ensure that the transition from engineering design to production design has not resulted in a loss of product quality or robustness. Some engineers may consider this approach as scientifically reasonable, but financially unrealistic. However, the cost of HALT testing is much less than the cost of field failures HIGHLY-ACCELERATED STRESS SCREENING (HASS) HASS testing is an on-going screening test, performed on regular production units. Here, the idea is not to damage the product, but rather to verify that actual production units continue to operate properly when subjected to the cycling of environmental variables used during the HASS test. The limits used in HASS testing are based on a skilled interpretation of the HALT testing parameters. The importance of HASS testing can be appreciated when one considers todays typical manufacturing scenario. Circuit boards are purchased from a vendor who uses materials purchased from other vendors. Components and sub-assemblies are obtained from manufacturers all over the world. Often, the final assembly of the product is performed by a subcontractor. This means that the quality of the final product is a function of the quality (or lack thereof) of all the components, materials, and processes which are a part of that final product. These components, materials, and processes can and do change over time, thereby affecting the quality and reliability of the final product. The best way to ensure that production units continue to meet reliability objectives is through HASS testing. RELIABILITY Reliability is defined as the probability that a device will perform its required function under stated conditions for a specific period of time. Predicting with some degree of Confidence is very dependent on correctly defining a number of parameters. For instance, choosing the distribution that matches the data is of primary importance. If a correct distribution is not chosen, the results will not be reliable. The confidence, which depends on the sample size, must be adequate to make correct decisions. Individual component failure rates must be based on a large enough population and relevant to truly reflect present day normal usages. There are empirical considerations, such as determining the slope of the failure rate and calculating the activation energy, as well as environmental factors, such as temperature, humidity, and vibration. Lastly, there are electrical stressors such as voltage and current. Reliability engineering can be somewhat abstract in that it involves much statist ics; yet it is engineering in its most practical form. Will the design perform its intended mission? Product reliability is seen as a testament to the robustness of the design as well as the integrity of the quality and manufacturing commitments of an organization. One of the fundamentals of understanding a products reliability requires an understanding of the calculation of the failure rate. The traditional method of determining a products failure rate is through the use of accelerated vibration operating life tests performed on a sample of devices. The failure rate obtained on the life test sample is then extrapolated to end-use conditions by means of predetermined statistical models to give an estimate of the failure rate in the field application. Although there are many other stress methods employed by electronic assembly manufacturers to fully characterize a products reliability, the data generated from operating life test sampling is the principal method used by the industry for estimating the failure rate of a electronic assembly in field service. Failure Rate (ÃŽÂ ») Measure of failure per unit of time. The useful life failure rate is based on the exponential life distribution. The failure rate typically decreases slightly over early life, then stabilizes until wear-out which shows an increasing failure rate. This should occur beyond useful life. Failure In Time (FIT) Measure of failure rate in 109 device hours; e. g. 1 FIT = 1 failure in 109 device hours. Total Device Hours (TDH) The summation of the number of units in operation multiplied by the time of operation. Mean Time between failures (MTBF) Reliability is quantified as MTBF (Mean Time Between Failures) for repairable product and MTTF (Mean Time To Failure) for non-repairable product. A correct understanding of MTBF is important. A power supply with an MTBF of 40,000 hours does not mean that the power supply should last for an average of 40,000 hours. According to the theory behind the statistics of confidence intervals, the statistical average becomes the true average as the number of samples increase. An MTBF of 40,000 hours, or 1 year for 1 module, becomes 40,000/2 for two modules and 40,000/4 for four modules. Sometimes failure rates are measured in percent failed per million hours of operation instead of MTBF. The FIT is equivalent to one failure per billion device hours, which is equivalent to a MTBF of 1,000,000,000 hours. The formula for calculating the MTBF is ÃŽÂ ¸ = T/R. ÃŽÂ ¸ = MTBF T = total time R = number of failures MTTF is stands for Mean Time To Failure. To distinguish between the two, the concept of suspensions must first be understood. In reliability calculations, a suspension occurs when a destructive test or observation has been completed without observing a failure. MTBF calculations do not consider suspensions whereas MTTF does. MTTF is the number of total hours of service of all devices divided by the number of devices. It is only when all the parts fail with the same failure mode that MTBF converges to MTTF. ÃŽÂ ³= T/N ÃŽÂ ³ = MTTF T = total time N = Number of units under test. If the MTBF is known, one can calculate the failure rate as the inverse of the MTBF. The formula for (ÃŽÂ ») is: where r is the number of failures. Once a MTBF is calculated, probability can derive from following equation: R(t) = e-t/MTBF Confidence Level or Limit (CL) Probability level at which population failure rate estimates are derived from sample life test. The upper confidence level interval is used. Acceleration Factor (AF) A constant derived from experimental data which relates the times to failure at two different stresses. The AF allows extrapolation of failure rates from accelerated test conditions to use conditions. Since reliability data can be accumulated from a number of different life tests with several different failure mechanisms, a comprehensive failure rate is desired. The failure rate calculation can be complicated if there are more than one failure mechanisms in a life test, since the failure mechanisms are thermally activated at different rates. Equation 1 accounts for these conditions and includes a statistical factor to obtain the confidence level for the resulting failure rate. THE BATHTUB CURVE The life of a population of units can be divided into three distinct periods. Figure 1 shows the reliability bathtub curve which models the cradle to grave instantaneous failure rates vs. time. If we follow the slope from the start to where it begins to flatten out this can be considered the first period. The first period is characterized by a decreasing failure rate. It is what occurs during the early life of a population of units. The weaker units die off leaving a population that is more rigorous. This first period is also called infant mortality period. The next period is the flat portion of the graph. It is called the normal life. Failures occur more in a random sequence during this time. It is difficult to predict which failure mode will manifest, but the rate of failures is predictable. Notice the constant slope. The third period begins at the point where the slope begins to increase and extends to the end of the graph. This is what happens when units become old and begin to fail at an increasing rate. Reliability Predictions Methods A lot of time has been spent on developing procedures for estimating reliability of electronic equipment. There are generally two categories: (1) predictions based on individual failure rates, and (2) demonstrated reliability based on operation of equipment over time. Prediction methods are based on component data from a variety of sources: failure analysis, life test data, and device physics. For some calculations (e.g. military application) MIL-HDBK-217 is used, which is considered to be the standard reliability prediction method. A simple failure rate calculation based on a single life test would follow equation 1. ÃŽÂ »Ã¢â€š ¬Ã‚  = failure rate. TDH = Total Device Hours = Number of units x hours under stress. AF = Acceleration factor, see Equation 3. Since reliability data can be accumulated from a number of different life tests with several different failure mechanisms, a comprehensive failure rate is desired. The failure rate calculation can be complicated if there are more than one failure mechanisms in a life test, since the failure mechanisms are thermally activated at different rates. Equation 1 accounts for these conditions and includes a statistical factor to obtain the confidence level for the resulting failure rate where, ÃŽÂ » = failure rate in FITs (Number fails in 109 device hours) ÃŽÂ ² = Number of distinct possible failure mechanisms k = Number of life tests being combined xi = Number of failures for a given failure mechanism i = 1, 2, ÃŽÂ ² TDHj = Total device hours of test time for life test j, j = 1, 2, k AFij = Acceleration factor for appropriate failure mechanism, i = 1, 2, k M = ÃŽ2 (ÃŽÂ ±, 2r +2) / 2 where, ÃŽ2 = chi square factor for 2r + 2 degrees of freedom r = total number of failures (ÃŽÂ £ xi) ÃŽÂ ± = risk associated with CL between 0 and 1. 2.2 SOLDER PASTE 2.1.1 ROLE OF SOLDER PASTE IN REFLOWING Solder paste is a combination mixture of a flux composition and a highly grinded, powdered solder metal alloy that is normally used in the electronics industry to soldering processes. And also it is call as a attachment medium between the device interconnection features and the PCB itself. The components of a solder paste are specially designed for excellent printing and reflow characteristics. In normal case of the surface mount soldering process involves placing the substrate and a small amount of solder paste in a printed circuit board. After that the system will be heated until the solder reflows, forms an electrical connection between the solder pad and the electrical contact of electronics part. After this reflow finished it forms both an electrical and mechanical connection between the electronics components and the printed circuit board. 2.1.2 SELECTION CRITERIA OF A SOLDER PASTE Selection of a solder paste is very important factor for reflowing process, reliability its quality. The following factors are considerable for a good solder paste [6]. The size of the solder alloy particles which are in the solder paste The tendency to form voids The properties of the flux medium of the solder paste Alpha particle emission rate The design of the stencil to be used for printing Thermal properties of the solder paste Electrical properties of the solder paste CHAPTER 03 EXPERIMENTS 3.1 MATERIALS AND METHODOLGY SOLDER PASTE Basically I used solder paste in same procedure. The details of solder paste used in the experiment are given in the following table TYPE OF SOLDER PASTE ALLOYS CODING PARTICLE SIZE METAL LOADIND S1 Sn95.5Ag4Cu0.5 S2 Sn42Bi57Ag1 Table 3.1.1 types of solder paste used in experiment For this project all above solder paste should be in a container with appropriate labelling and identification on it to distinguish it from the Tin lead solder paste. The solder paste should be stored in a refrigerator between 35 45 F. and should be allowed to come room temperature for minimum four hours before doing the solder paste printing. Once it has finished the using solder paste must replace to the refrigerator since it can not be at room temperature over 24 hours. The self life of the lead free solder pastes may be reducing from the typical six month. The above guidelines are strictly followed in this project. Because it is not only for guarantee the quality of solder paste but also a good way to reduce the errors that may affect the final results of the project. SOLDER PASTE PRINTING IMPORTANT OF SOLDER PASTE PRINTING Surface mount technology (SMT) is used extensively in the electronics industry. Surface mount components are potentially more reliable products can be designed and manufactured using the SMT. The solder paste stencil printing process is very critical and important step in the surface mount manufacting process. Most of all the soldering defects are due to problems dealing with the screening process. So we want to a major consideration in operation and set up steps in stencil printing process. When we are monitoring these factors carefully we can minimize the defects. The main purpose of printing solder paste on PCB is to supply solder alloy to solder joint to correct amount. That only print must be aligned correctly and can get a perfect component placement. PRINTING PROCESS PARAMETERS Some of the following parameters are very important to printing process. STENCIL Stencils are using for the solder paste slip easily off the aperture edges and thereby secures a uniform print. For this process we using electro formed stencils. Because of these stencils have very shape edge and slightly conic. Generally a stencil is mading from cupper or nickel [12]. ENVIRONMENTAL Dust and dirt from the air that will reach the PCBs and stencils can be defects poor wet ability in the reflow soldering process. So PCBs should be stored in sealed packages and cleaned before use. SOLDER PASTE Solder paste characterise must be controlled to achieve a maximum production results. Some of the factors are given below [12]. Percent of metal Viscosity Slump Solder balls Flux activity working life and shelf life STENCIL PRINTING PARAMETERS Stencil printing parameters are very important factors in printing processes to achieve a best yield. The following parameters must be monitors and controlled in a printing process. Squeegee pressure = 8kg Squeegee speed = 20 mm/s Separation speed = 100% Printing gap = 0.0 mm These factors and limit can be adjust for our project purpose SOLDER PASTE PRINTING EQUIPMENT AND PROCESS Figure 3.2.4.1 DEK 260 stencil printing machine The DEK 260 stencil printing machine is used to print solder paste on the circuit board. This DEK 260 stencil printing machine has two main functions. Registers the position of the product screen with in the print head Positioning the circuit board below the stencil, to ready for the print cycle. The boards to be print are supported on magnetic tooling and held by vacuum caps arranged on the plate to guarantee the board steady during the printing on to the board. The first step of the experiment is to do the solder paste printing on to the board. In this project unable to get metal stencil, so circuit boards are printed by hand, below procedure followed to print PCB Put weights onto the stencil to fix it roll the squeegee over the stencil solder paste presses through the aperture onto PCB separate stencil two circuit boards are printed with solder paste for each solder paste types. Totally 4 circuit boards printed. SOLDER PASTE REFLOWPROCESS/PROFILE Figure 3.3.1 reflow oven To achieve a good reliable solder joint the reflow process is very important. When doing the reflow with sn-pb solder paste often performed at minimum peak temperature of about 203. It is 20k above the sn pb liquid state temperature. When doing the reflow process with lead free solder paste it has to be performed at a minimum peak temperature of 230. It is just 13K above the melting temperature. It is generally accepted that lead free solders requires a higher reflow temperature up to 220 230. Reflow profile will be affecting the reliability of a solder joint. Because it is a major factor that influence the formation of the intermettallic layers in a solder joint. Intermettalic layer is a critical part of a solder joint. An intermettalic bond thickness should be thin. Therefore a good reflow profile must produce solder bumps with a thin intermetallic layer. PREHEAT ZONE In this zone indicates how the temperature is changing fast on the printed circuit board. The ramp-up rate is usually between 1-3 per second. If this rate exceeds there will be damage to components from thermal shock. Only In this preheat zone the solder paste begins to evaporate. So if the rise rate is too low the evaporation of flux is not incomplete. This will affect the quality of the solder joint. THERMAL SOAK ZONE It is also called the flux activation zone. In this thermal soak zone it will take 60-120 seconds for removal of solder paste and activation of fluxes. Solder spattering and balling will be happen if the temperature is too high or too low. End of this thermal shock zone a thermal equilibrium will complete the entire circuit board. REFLOW ZONE In this reflow zone only the maximum temperature will be reached. In this zone we have to consider about the peak temperature that is the maximum allowable temperature of entire process. It is very important to monitor this maximum temperature exceeds the peak temperature in this zone. It may cause damage to the internal dies of SMT components and a block to the growth of intermetalic bonds. we have to consider the profile time also. If time exceeds than the manufactures specification it also affect the circuit boards quality. 3.3.4 COOLING ZONE In the reflow process the last zone is cooling zone. A proper cooling inhabits excess intermetallic formation or thermal shock to the components. Generally the cooling zone temperature range is 30 100. In this project I selected the following temperature profiles. This temperature profile is stranded reflow profile for lead free soldering. Zone 1 220 Zone 2 180 Zone 3 170 Zone 4 190 Zone5 233 Zone 6 233 Totally 4 circuit boards were printed. Choosing of good reflow profile was not involves any defects or damages in the printed circuit board. Figure 3.3.4.1a printed circuit board after reflow SET UP EVENT DETECTOR The constructed PCBs were connected with event detector by ribbon data cable. Ribbon cable addressed according to `Analysis tech STD series event detectors manual . pins 1 to 32 function as source point and pins 33 to 37 function as ground point. To obtain closed loop circuit to monitor the behaviour of PCB components, PCB boards 1, 2, 3 and 4 connected to channel 1,2,33 and 34 respectively. Ribbon cable After connected ribbon cable with event detector and enviromenrt chamber, channels are assigned in WIN DATA LOG software which supplied with event detector. For this test following settings define for data acquisition INVESTICATING RELIABILITY OF SOLDER JOINT UNDER VIBRATION CHAMER In this study, PCBs were used in Variable Frequency Vibration Test to analyse the dynamic response of PCB assembly subjected to random vibration loading. The PCB specimens were tested at different acceleration levels to assess the solder joint reliability subjected varying G-level vibration loads(G is the gravitational acceleration), respectively. Vibration tests were accomplished by using an electro dynamic Shaker