In case you missed it.

Business Management

"Calling a Change in the Outsourcing Market"

Authors: Kenneth Landis, Somnath Mishra and Kenneth Porrello; [e-mail].

Abstract: Emerging evidence indicates mixed outsourcing results. This in-depth study of outsourcing strategies looks at the impact on organizational performance and nascent outsourcing trends. Participants represent 25 world-class organizations in manufacturing and other sectors, half of which are part of the Fortune 500. Organizations have now begun to recognize the real costs and inherent risks of outsourcing. Instead of simplifying operations, outsourcing often introduces complexity, increased cost and friction into the value chain, requiring more senior management attention and deeper management skills than anticipated. In addition, outsourcing has permitted organizations to transfer financial and operational risk to vendors, but organizations are discovering that their contracts will never fully protect them against customer damage and business losses caused by service disruption. Many have responded by bringing operations back in-house and by exploring alternatives to traditional outsourcing, such as the trans-form-operate-transfer model. The study found that measuring quality is standardized in product sourcing, yet tricky in services outsourcing, and that second sourcing is unsuitable for services outsourcing, leading to higher dependency on vendors. The result: complexity in place of simplicity. The study found that 70% of the participants have had negative outsourcing experiences and have either revised or are revising their outsourcing outlook, strategies and tactics. These are the more experienced organizations, and they will continue to move forward with outsourcing but with increased scrutiny. (Deloitte Consulting white paper, April 2005)

Conformal Coatings

"Evaluation of Conformal Coatings as a Tin Whisker Mitigation Strategy, Part II"

Authors: Thomas A. Woodrow, Ph.D., and Eugene A. Ledbury; [e-mail].

Abstract: The second phase of an ongoing study of the ability of conformal coatings to mitigate the formation and growth of tin whiskers. Conformal coatings were chosen as a mitigation strategy because they are one of the few processes actually under the control of OEMs that manufacture high-reliability electronics. Brass coupons were plated with bright tin and then conformal coatings were applied. The coupons were aged in a 25[degrees]C/97% RH (relative humidity) environment and observed for whisker formation and whisker penetration of the coatings. The results of this test suggest that conformal coatings can suppress the formation of whiskers and OSEs (odd-shaped eruptions). With time, however, all coupons in this test began to grow whiskers under the coatings, and once whisker growth began, all coatings were penetrated regardless of thickness. These observations differ from a prior study in which the coupons were aged in a 50[degrees]C/50% RH environment. In that study, whiskers or OSEs penetrated only the thinner coatings (less than 0.0015") during the test. This study observed unusual eruptions of tin that were capped with a thick crust of material. Auger analysis suggested that the crust was a mixture of tin, tin oxide and zinc oxide. (SMTAI, September 2006)

Reliability

"Epidemiological Study on SnAgCu Solder: Benchmarking Results from Accelerated Life Testing"

Authors: Craig Hillman, Nathan Blattau, Ed Dodd and Joelle Arnold; [e-mail].

Abstract: The results of a comprehensive overview of accelerated life testing (ALT) of components assembled with SnAgCu solder. More than 100 private documents and published articles were assessed for data on SAC performance under temperature cycling. Data on test parameters, component materials and design, and interconnect dimensions were acquired and results grouped by attach geometry, including leadless (i.e., chip resistors), stiff lead (i.e., alloy 42) and solder ball (i.e., CSP, BGA). A particular emphasis was placed on obtaining temperature cycling data over a wide range of dwell times (5 to 360 min.). Discussions focus on trends in performance and will provide guidance on times-to-failure under standard industry and military test specifications. (SMTAI, September 2006)

"QFN 9X9 Solder Joint Reliability"

Author: Michael Hundt

Abstract: This study investigated the impact of high current on solder joint reliability of QFNs, evaluated internal versus external heating of the packages for +125[degrees]C applications, and investigated SAC vs. SnPb solder options. The main factors for solder joint reliability were package size, die-to-die pad ratio, solder standoff, PCB thickness and land size. The die-to-die pad ratio was the critical factor. Simulation data showed that solder joint reliability can be improved significantly when the ratio is lower than 0.4. It was found that survival was much greater than expected. QFNs with SAC solder were shown to be 25% less reliable. There was no reliability difference found attributable to high current, and no significant difference for internal versus external temperature. While the manufacturing process for QFNs was found to be less robust, the 9X9 package exceeded requirements for under-the-hood automotive applications. (SMTA Harsh Environments Workshop, July 2006)

CIRCUITS ASSEMBLY provides abstracts of papers from recent industry conferences and company white papers. With the amount of information increasing, our goal is to provide an added opportunity for readers to keep abreast of technology and business trends.