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Article
Publication date: 18 September 2009

Jianbiao Pan, Tzu‐Chien Chou, Jasbir Bath, Dennis Willie and Brian J. Toleno

The purpose of this paper is to investigate the effects of reflow time, reflow peak temperature, thermal shock and thermal aging on the intermetallic compound (IMC) thickness for…

559

Abstract

Purpose

The purpose of this paper is to investigate the effects of reflow time, reflow peak temperature, thermal shock and thermal aging on the intermetallic compound (IMC) thickness for Sn3.0Ag0.5Cu (SAC305) soldered joints.

Design/methodology/approach

A four‐factor factorial design with three replications is selected in the experiment. The input variables are the peak temperature, the duration of time above solder liquidus temperature (TAL), solder alloy and thermal shock. The peak temperature has three levels, 12, 22 and 32°C above solder liquidus temperatures (or 230, 240 and 250°C for SAC305 and 195, 205, and 215°C for SnPb). The TAL has two levels, 30 and 90 s. The thermally shocked test vehicles are subjected to air‐to‐air thermal shock conditioning from −40 to 125°C with 30 min dwell times (or 1 h/cycle) for 500 cycles. Samples both from the initial time zero and after thermal shock are cross‐sectioned. The IMC thickness is measured using scanning electron microscopy. Statistical analyses are conducted to compare the difference in IMC thickness growth between SAC305 solder joints and SnPb solder joints, and the difference in IMC thickness growth between after thermal shock and after thermal aging.

Findings

The IMC thickness increases with higher reflow peak temperature and longer time above liquidus. The IMC layer of SAC305 soldered joints is statistically significantly thicker than that of SnPb soldered joints when reflowed at comparable peak temperatures above liquidus and the same time above liquidus. Thermal conditioning leads to a smoother and thicker IMC layer. Thermal shock contributes to IMC growth merely through high‐temperature conditioning. The IMC thickness increases in SAC305 soldered joints after thermal shock or thermal aging are generally in agreement with prediction models such as that proposed by Hwang.

Research limitations/implications

It is still unknown which thickness of IMC layer could result in damage to the solder.

Practical implications

The IMC thickness of all samples is below 3 μm for both SnPb and SAC305 solder joints reflowed at the peak temperature ranging from 12 to 32°C above liquidus temperature and at times above liquidus ranging from 30 to 90 s. The IMC thickness is below 4 μm after subjecting to air‐to‐air thermal shock from −40 to 125°C with 30 min dwell time for 500 cycles or thermal aging at 125°C for 250 h.

Originality/value

The paper reports experimental results of IMC thickness at different thermal conditions. The application is useful for understanding the thickness growth of the IMC layer at various thermal conditions.

Details

Soldering & Surface Mount Technology, vol. 21 no. 4
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 18 September 2009

Martin Goosey

249

Abstract

Details

Soldering & Surface Mount Technology, vol. 21 no. 4
Type: Research Article
ISSN: 0954-0911

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Article
Publication date: 1 April 1995

Dennis Isbell and Dorothy Broaddus

Arizona State University (ASU) West is a new, upper division undergraduate and graduate campus serving western Maricopa County and metropolitan Phoenix. The students are typically…

319

Abstract

Arizona State University (ASU) West is a new, upper division undergraduate and graduate campus serving western Maricopa County and metropolitan Phoenix. The students are typically working adults from the community who come from a variety of ethnic backgrounds. Most are drawn from the local community colleges, where they complete their first two years of college before entering ASU West.

Details

Reference Services Review, vol. 23 no. 4
Type: Research Article
ISSN: 0090-7324

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Book part
Publication date: 26 November 2020

Carlos M. Cervantes and Langston Clark

Given their history of preparing African Americans, ethnic minorities, and first-generation college students for careers in education, the culture and traditions of Historically…

Abstract

Given their history of preparing African Americans, ethnic minorities, and first-generation college students for careers in education, the culture and traditions of Historically Black Colleges and Universities (HBCU) can provide insight into the preparation of diverse physical educators for the cultural, linguistic, and ethnic diversity in today’s American K-12 schools. As such, this chapter will present practical findings from an ethnographic study of a historically Black urban Physical Education Teacher Education (PETE) program with a large native Spanish-speaking population. Specifically, we focus on the concepts of cultural sustainment and code-switching as strategies used by teacher educators to promote bilingualism and biculturalism. To achieve this, we highlight the relationship among institutional, programmatic, and classroom cultures for the cultural ­sustainment and development of preservice physical educators. According to Paris (2012), culturally sustaining pedagogy seeks to perpetuate and foster linguistic, literate, and cultural pluralism as part of the democratic project of schooling. We conclude with strategies on how to successfully work with culturally diverse college students, promoting bilingual and biculturalism through cultural sustainment and code-switching.

Details

Technology-enhanced Learning and Linguistic Diversity: Strategies and Approaches to Teaching Students in a 2nd or 3rd Language
Type: Book
ISBN: 978-1-83982-128-8

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Book part
Publication date: 21 August 2017

Taylor Price and Antony Puddephatt

Open access publishing is an increasingly popular trend in the dissemination of academic work, allowing journals to print articles electronically and without the burden of…

Abstract

Open access publishing is an increasingly popular trend in the dissemination of academic work, allowing journals to print articles electronically and without the burden of subscription paywalls, enabling much wider access for audiences. Yet subscription-based journals remain the most dominant in the social sciences and humanities, and it is often a struggle for newer open access publications to compete, in terms of economic, cultural, and symbolic capital (Bourdieu, 2004). Our study explores the meanings of resistance held by the editors of open access journals in the social sciences and humanities in Canada, as well as the views of university librarians. To make sense of these meanings, we draw on Lonnie Athens’ (2015) radical interactionist account of power, and expand on this by incorporating George Herbert Mead’s (1932, 1938) theory of emergence, arguing that open access is characteristic of an “extended rationality” (Chang, 2004) for those involved. Drawing on our open-ended interview data, we find that open access is experienced as a form of resistance in at least four ways. These include resistance to (1) profit motives in academic publishing; (2) access barriers for audiences; (3) access barriers for contributors; and (4) traditional publishing conventions.

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Oppression and Resistance
Type: Book
ISBN: 978-1-78743-167-6

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Book part
Publication date: 26 May 2015

Donald Cunnigen and Robert Newby

Barack Obama has had considerable support among scholarly circles since his win in the Iowa primary in early 2008. A segment of the Association of Black Sociologists (ABS), “Black…

Abstract

Purpose

Barack Obama has had considerable support among scholarly circles since his win in the Iowa primary in early 2008. A segment of the Association of Black Sociologists (ABS), “Black and Progressive Sociologists Obama Working Group (BPSOWG),” was particularly active during the 2008 campaign. The purpose of this chapter was to determine if the level and type of activism among this group differed from other progressive groups of sociologists.

Methodology/approach

The data for this study were collected from a web-based survey administered to approximately 800 professional sociologists in the United States. The survey consisted of items that focused on the extent to which respondents supported the Obama campaign for the presidency and the extent to which they were satisfied with and/or agreed with his policies during first two years of his presidency.

Findings

The response rate for the survey was 40% (N=305) and 96% of respondents (N=293) submitted surveys with complete information. Over two-thirds of participants were members of the American Sociological Association Section on Race and Ethnic Relations and 5.5% of respondents identified themselves as members of the BPSOWG. A slight majority (53.6%) of study participants were females and the largest two racial groups making up the study population were whites (47.1%) and African Americans (36.1%). Most of the respondents provided support for President Obama during his first campaign, including financial contributions (66%).

Originality/value

Sociologists who responded to the survey were generally positive about Barack Obama as a candidate and a President. However, the subtle differences between groups about Obama administration policies and the use Presidential power highlighted key areas in which diverse coalitions for progressive change are needed.

Details

Race in the Age of Obama: Part 2
Type: Book
ISBN: 978-1-78350-982-9

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Book part
Publication date: 1 October 2008

Rutledge M. Dennis

I don’t remember exactly when I began to be interested in music, but my mother and godmother would laughingly recall when they knew I would be musically inclined. Though I was…

Abstract

I don’t remember exactly when I began to be interested in music, but my mother and godmother would laughingly recall when they knew I would be musically inclined. Though I was then in diapers, whenever Tommy Dorsey's recording of Boogie Woogie was played, I would immediately begin to pat my feet. My first conscious memory of reacting to music when I was very young were the times my father would sing little ditties and play his banjo. He could carry a tune, and he played the banjo quite well. His greatest musical feat, however, was as a whistler, and I would try to imitate his whistling style, without success as I grew older. Then too, my siblings and I would sing and recite little nursery rhymes before our parents, and I would compose songs for my sisters to sing. Before he died an early death at 37 my father gave me a mouth harp and a harmonica which I kept for many years; I later misplaced it while in college. I later bought another harmonica which I kept throughout my years in the U.S. Army, my travels throughout Europe, and throughout my years in graduate school. How and why we each possess the talents and skills we have are questions I’ve never fully understood. So I’ve concluded that we just have them, and we’ll never be able to explain it. Throughout this chapter four reference points will be used to explain my exposure to music and my music biculturality: schools, churches, home, and my neighborhood. If I make very few references to whites, it is simply because during my early life my contact with whites was minimal, and white individuals played a minor role in my life, as at home my world centered around my parents and godparents, siblings, and other family members, and neighborhood friends; at school my world was a completely black world. The first white I got to know outside of my early work experiences was the white Presiding Bishop of the Reformed Episcopal Church who visited St. John's Episcopal Church at least six or seven times a year.

Details

Biculturalism, Self Identity and Societal Transformation
Type: Book
ISBN: 978-0-7623-1409-6

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Book part
Publication date: 1 October 2008

Rutledge M. Dennis

How we become a part of group, identify with the group, and acquire a “we” feeling is both simple and complex. We may absorb groupness either because we were born into the group…

Abstract

How we become a part of group, identify with the group, and acquire a “we” feeling is both simple and complex. We may absorb groupness either because we were born into the group, or because we have made a decision to choose membership into the group. In this subsection the former will be our focus, and since we have already broached the African American theme we will explain collective identity matters from this perspective.

Details

Biculturalism, Self Identity and Societal Transformation
Type: Book
ISBN: 978-0-7623-1409-6

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Book part
Publication date: 24 October 2017

Abstract

Details

Corruption, Accountability and Discretion
Type: Book
ISBN: 978-1-78743-556-8

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Book part
Publication date: 18 September 2024

Berch Berberoglu

Abstract

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Class and Inequality in the United States
Type: Book
ISBN: 978-1-80043-752-4

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