The Computer Aided Life Cycle Engineering (CALCE) Electronic Products and Systems Center (EPSC) of the University of Maryland has recently become the world’s first academic research organization to be awarded ISO 9001 Certification. The award of ISO 9001 certification highlights CALCE’s continuing effort to provide a culture of research and educational excellence.
CALCE Director, Professor Michael Pecht, has noted that "Since industry has been successful in improving the quality of its processes by adopting ISO 9001, why shouldn’t academic R&D use the same standards?"
The ISO 9001, created by the International Organization for Standardization in Geneva, Switzerland, is comprised of selected quality assurance and quality management standards. These standards are not specific to products and services, but concern the processes responsible for creating them. ISO standards are generic in nature and hence have a universal application.
The CALCE ISO certification process took a little over a year to develop and implement. Its implementation has produced many positive results. Internally, it focused performance on quality, increased operational efficiency
and enhanced communications. Externally, it increased attention to our customers (students and sponsors), their needs and perspectives, renewed focus on innovative long-term research programs and introduced higher perceived quality.
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CALCE Laboratory Services provides assistance and research in advanced electronic systems through consulting services for the electronics
industry. The services provided are in the areas of supplier benchmarking, failure analysis, reliability assessment, material characterization and simulation. The following are just a few recent contributions that Laboratory Services has made to address and solve industry problems.
Hollow Fibers Research at CALCE Results in New Guidelines for Industry
CALCE Laboratory Services, currently the only independent laboratory performing hollow fiber assessment, has been using its expertise industry-wide to prevent conductive filament formation (CFF) due to hollow fibers. CALCE recommendation for hollow fiber assessment has now become a standard screening guideline for major board fabricators and contract assemblers. Nanya Plastics, one of the world’s largest glass fiber manufacturers, has revised its glass production process as a result of CALCE research and experienced nearly hollow-free fiber concentrations. Guidelines provided by CALCE allow no greater than 1 hollow fiber per 10cm x 10cm. These newly developed guidelines introduced by CALCE have enabled OEMs to qualify suppliers and detect lots with compromised hollow fiber concentrations.
CALCE Prevents Product Defects by Evaluating Manufacturing Procedures
As part of a comprehensive failure analysis methodology, CALCE Laboratory Services frequently conducts reviews of manufacturing processes. Recently, four hermetically sealed diodes that failed during a company screening, were brought to CALCE for evaluation. Through the assessment of the company’s manufacturing process, CALCE Laboratory Services determined that the high temperature steps used in the hermetic sealing were contributing to the creation of latent defects. CALCE recommended a change in the plating materials or the use of plastic packages, which have similar or higher reliability rates than hermetic packages in similar environments, and enabled the company to meet delivery deadlines.
Supplier Benchmarking Leads to Rapid Growth for Pre-IPO Telecommunication Firms
Laboratory Services has recently partnered with a number of small, rapidly growing companies that produce routers and servers for the Internet. Reliable products and costeffective manufacturing are critical to the success of such start-up companies involved in leading-edge technology. In response to their needs, CALCE has provided an allinclusive service, which included a broad range of assistance, from failure analysis to reliability assessment, and from material characterization to stress simulations. Of critical importance has been CALCE benchmarking of suppliers. In three case studies, CALCE Laboratory Services benchmarked contract board manufacturers, contract assemblers and ceramic capacitor suppliers. The results helped prevent costly delays due to suppliers’ inadequate quality systems.
Boeing to Use CALCE Technical Input for Design Guidelines
CALCE was asked to provide technical input so that Boeing could validate the suitability of IPC-2221 with regards to dielectric breakdown. This assessment provided critical information on the intrinsic safety factors designed into the IPC standards. This data will be used by Boeing to establish design guidelines that ensure optimum use of board real estate while still maintaining high reliability.
Mixed Flowing Gas (MFG) Testing Available at CALCE
CALCE is one of a small number of laboratories with the capability of performing mixed flowing gas MFG) testing. MFG testing exposes contacts and connectors to the four most common corrosive gases in the environment, SO2, H2S, NO2, and Cl2. Using a known acceleration factor, MFG exposure can simulate long-term use in office and industrial environments. As a result of its effectiveness, MFG testing is often a requirement specified by OEMs in the telecommunication industry. CALCE has conducted this research for a variety of industrial customers, including S.C. Johnson and Kings Electronics.
Teradyne Is Served by Time Efficient and Low Cost Design Analysis at CALCE
Design validation is another important service offered by CALCE. A recent example of this service involved examining the relative robustness of interconnect geometries developed by Teradyne. The use of an energy-partitioning model, developed at the Center, enabled CALCE to conduct the validation in an efficient and cost effective manner. Results provided Teradyne with an estimated time-to-failure during accelerated testing and operation.
CALCE Screening Assessments Benefit NASA Contractor
CALCE Laboratory Services helped a NASA contractor avoid making an erroneous decision due to flawed screening process of power diodes. The diodes were originally subjected to a current surge test, which resulted in failure rates in excess of 15%, unacceptable for mission-critical parts. To assess the validity of such a screening process, CALCE Laboratory Services simulated the contractor’s test using CALCE-developed CADMP-II software and determined, through a physics-of-failure analysis, that the test was excessive and induced failures which would never occur during normal operation.
CALCE Assists in Ball Grid Array Optimization Program
CALCE Laboratory Services frequently works with suppliers and OEMs on optimizing aspects of the manufacturing process. Studies were recently conducted to optimize BGA solder ball shear strength as a function of pad geometry (circular vs. square), plating material (gold, nickel, OSP) and pad cleaning solutions. Tests which measured shear strength relative to these parameters allowed the companies involved to select plating materials, cleaning techniques, and pad geometry to provide maximum shear strength.
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Durability Concerns With new environmental legislation pending in Europe and many Japanese companies already making the transition to lead-free solders, American companies are contemplating a replacement for SnPb eutectic solder.
A recent survey by the National Electronics Manufacturing Initiative (NEMI) suggests that the most favored candidate is the ternary SnAgCu alloy for reflow soldering operations. This alloy was not on the list of solders studied earlier by an industry-CALCE consortium in 1997 (National Center for Manufacturing Sciences, Lead-Free Solders Project), and hence requires further study. Preliminary work on this solder alloy has focused on the manufacturability and the impact of its use on existing processes and products. However, there is a marked lack of information regarding the mechanical properties and durability of this alloy. CALCE research is currently focusing on this vital piece of information using the Thermo-Mechanical-Microstructural (TMM) materials characterization methodology developed earlier on other
CALCE projects.
The TMM test system is currently being used to characterize the constitutive properties and fatigue durability of SnPb eutectic and Sn62Pb36Ag2 solder. Characterization of this lead-free solder alloy involves an array of monotonic, constant load creep, and cyclic mechanical durability tests on specially designed test specimens, and a quantitative understanding of the intermetallics formed with commonly used metallization systems on PWBs and components. The experimental data, combined with numerical simulation of the test specimen and test conditions, yields complete information required for assessing the alloy’s thermo-mechanical performance in actual products. While there are several variations of the SnAgCu system available from different suppliers, this study will focus on an alloy with a silver content of 3.5-3.9 wt.% and a copper content of 0.6-0.8 wt.%. For more information regarding CALCE research in this area, please contact Dr. Abhijit Dasgupta at (301) 405-5251 or email: dasgupta@eng.umd.edu.
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Advanced electronic packaging is nowhere more evident than in portable electronics such as cell phones, pagers, and PDAs. By their very nature, portable electronics present the packaging engineers with a variety of challenges. The package must be ergonomically appealing while protecting the electronic devices housed within it. These structures must hold up to loads produced by mishandling, such as impact induced by accidental drops.
Drop conditions are more complex than other environmental conditions since the dynamics of the impact can have multiple variations. The ability to quantify the damage, produced by impact, and inertia loads presents major technical challenges in both numerical and experimental analyses. An immediate technical challenge is encountered when a product is to be assured to withstand nominal drops (product reliability). A subsequent technical assessment must proceed to quantify the extent of damage induced by drops (product durability and warranty).
CALCE has recently initiated research on reliability assessment and design optimization of portable electronics. This research will focus on three major areas of impact loading: (1) failure identification, (2) test tailoring methodology and (3) quantitative damage characterization. It is expected to deliver: (1) instrumentation of drop tower, (2) detailed record of product drop tests and failure analysis, (3) identification of common failures observed across different products, (4) quantitative damage data induced by impact loading and subsequent thermal cyclic loading, (5) Physics of Failure simulations of impact failure and (6) reliability assessment and life prediction models. Demands for cutting edge technologies are continuously increasing and so is the demand for smaller and smarter portable electronics. Successful completion of this research will help reduce development cycle time of new portable electronics products by optimizing reliability and durability while meeting required levels of quality and robustness. For more information, contact Dr. Bongtae Han at (301) 405-5255 or bthan@calce.umd.edu.
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An imperative need for quantitative deformation data for microelectronics devices has been acknowledged. This need becomes more pressing as the devices become smaller and product development cycle time becomes shorter. The Laboratory for Opto-mechanics and Multi-layer Systems (LOMS) has
been established for the CALCE member companies to meet this demand.
The LOMS is currently equipped with various classical and modern photomechanics methods for quantitative experimental studies of multi-material miniature structures, specifically microelectronics packaging materials and subassemblies. The methods utilize optical systems, providing whole-field displacement information with various sensitivities and resolutions, and have been applied successfully to various problems encountered in microelectronics product development (B. Han and Y. Guo, Photomechanics Tools as Applied to Electronic Packaging Product Development, B. Han, et al., ed., E/NMEP, Vol. 1, SEM, Bethel, CT, (April 1997)).
Methods include moiré interferometry, microscopic moiré interferometry, Twyman/Green interferometry, far infrared Fizeau interferometry and shadow moiré. The first two provide contour maps of inplane displacement fields and the next three out-of-plane displacement fields. The in-plane displacement fields are required for strain analyses, and the out-of-plane displacement fields are used for warpage or co-planarity measurement. The methods are typically implemented with a computer controlled environmental chamber to document deformations as a function of temperature. The in-situ and quantitative nature of the methods will lead to more accurate and realistic understanding of the macro and micro thermomechanical behavior of package assemblies and interconnections, which, in turn, will facilitate design evaluation for optimum reliability at an early stage of product development. For more information, contact Dr. Bongtae Han at: 301-405-5255 or bhan@calce.umd.edu.
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The future of electronics will witness the advent of microelectronic systems that will control and manipulate larger power densities and operate in more extreme environments. These systems are needed for 21st century vehicles, including the more-electric aircraft, the electric submarine, the all-electric tank, the fly-by-wire commercial aircraft, and the hybrid electric vehicle. Development of such systems is being driven by the Office of Naval Research, the Air Force Office of Scientific Research, the Defense Advanced Research Projects Administration, and the Department of Energy, along with commercial avionics and automotive industries.
In order to make these systems a reality, CALCE and the Electronic Components Alliance have been developing decision support software for power electronics. This work, funded by the Office of Naval Research’s Power Electronics Building Blocks (PEBB) program, involves creating an integrated suite of software tools that optimize electronic module designs with respect to performance, reliability, and cost. Separate program elements have been created that provide cost analysis, thermal analysis, and application specific reliability assessment for potential power module designs. The results of these analyses are provided to an optimizer that ranks each design on the basis of how well it fits a number of defined design objectives. The optimizer then uses genetic algorithms to generate a new set of potentially improved design parameters for the next analysis. This system was successfully demonstrated at the Power Systems World Conference in Chicago, IL in November 1999.
In addition to software development, the Electronic Components Alliance has been actively working with member companies ABB, DaimlerChrysler, International Rectifier, Siemens, and SPCO, in the development and evaluation of next generation power technologies. The Alliance currently has projects involving micro and nano-scale structural analysis of die attach and solder materials, developing new methods of bonding attachment, creating pressure based contact systems, and investigating the effects of plastic encapsulation on power device reliability. The results of all of these research efforts will be transferred to the Alliance membership both through publications and reports and by incorporation into the CADMP-II module level reliability assessment software.
For further information on CADMP-II, the Electronic Components Alliance, or our power electronics efforts, please contact Dr. Patrick McCluskey at (301) 405-0279 or mcclupa@calce.umd.edu.
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IEEE 1413 Standard Methodology for Reliability Prediction and Assessment for Electronic Systems and Equipment establishes the framework around which a reliability prediction methodology must be developed. The standard identifies key required elements for an understandable, credible reliability prediction and provides the users sufficient information to evaluate prediction methods and to effectively use their results. To benefit from the IEEE standard, customers must require that their suppliers use IEEE 1413 compliant reliability predictions to provide reliability prediction results. The CALCE Consortium is currently evaluating various reliability prediction processes against the criteria established in IEEE 1413. Prediction processes that are currently under review include: Mil-Hdbk-217F SAE's Method, Siemens SN 29500, RAC’s system reliability assessment method, British Telecom HRD 5, Physics of failure, Bellcore TR-332, CNET RDF 93, and Honeywell’s top down similarity analysis method.
The IEEE Standard Association has recently elected a new committee chaired by CALCE Director, Dr. Michael Pecht, to promote processes and methodologies for predicting the reliability of electronic systems and equipment. One of the central functions of this group is to develop a guide that will concentrate on reliability prediction methods and verification components, systems and software, as well as provide in-depth analysis of reliability metrics, goals, and allocations. The framework established in IEEE 1413 will be used to develop the guide. References and research will come from CALCE and several IEEE groups.
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The International Electrotechnical Commission (IEC) is the international standards and conformity assessment body for all fields of electrotechnology. The Avionics Working Group (AWG) was set up with a mission to develop and maintain industry procedures for electronic component management in the avionics industry. CALCE EPSC had been an active participant in all the activities of the AWG. CALCE has provided the technical input for AWG guidebook QC001007-1-2 "Guide for Using Semiconductor' Devices Outside Manufacturers' Specified Temeperature Ranges." This guidebook will be presented to the IEC for approval in the year 2000. Dr. Diganta Das, a Research Associate at the CALCE Center made a well-received presentation at the "Commercialization of Military and Space Systems Workshop," at Los Angeles in January 2000. CALCE is now working with the Avionics Working Group on the development of an avionics technology roadmap.
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During an assessment of ATMEL plastic packaged surface mount parts for AlliedSignal, ATMEL (a worldwide leader in the design, manufacturing and marketing of advanced semiconductors) noted that their procedures and guideline conform to best industry proactices, and provided a CALCE publication (P. Gannamani, R. Munamurthy, P. McCluskey and A. Christou, Optimum Processing Prevents PQFP Popcorning, SMT, pp. 39-42, May 1995) as their guideline.
CALCE has worked on the development of reflow soldering profiles for plastic parts to minimize damage due to accumulated moisture. Portions of this work have been adopted by the IPC/JEDEC J-STD-020A standard (Moisture.Reflow Sensitivity Classification for Plastic Integrated Circuit Surface Mount Devices). In the CALCE parts selection and management guidebook, one of the criteria for rating a part manaufacturer is the availability of end-use assembly information.
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