National Center For Manufacturing Sciences Research Articles

Collaborative Development of a Functional Trivalent Chromium Electroplating Process

Faraday has been working for over 20 years on the development of a functional chromium plating process from a trivalent-based electrolyte to replace hexavalent chromium plating. Hexavalent chromium plating has been used for many decades to provide hard, durable coatings with excellent wear and corrosion resistance properties. However, hexavalent chromium has come under increasing scrutiny due to the toxic nature of the bath, effects on the environment, and workers’ health. Faraday has demonstrated that the chrome coatings prepared using the FARADAYIC(R) Process have equivalent functional properties to the coatings produced with a hexavalent chromium bath. The data demonstrates equivalent or superior: 1) plating rate, 2) Knoop hardness, 3) current efficiency, 4) hydrogen embrittlement behavior, 5) adhesion, 6) corrosion resistance, 7) porosity, 8) thickness, 9) Taber Abrasion, Ball on Flat Reciprocating and Dithering wear resistance, and with no hexavalent chromium formation in the bath. The data that will be presented demonstrate the feasibility of the process and have provided the basis for further technical qualification and prototype design. Of note, due to the promise of this technology, Faraday’s team received a 2013 Presidential Green Chemistry Challenge Award. The long development time frame of 20+ years for development, testing and adoption of a new coating process is not uncommon in the aerospace industry, the primary target of Faraday’s trivalent chromium plating process. This is due, in part, to rigorous testing requirements. In addition, the development of a paradigm shifting innovation can be an arduous and lengthy process. The initial phases of this development process were conducted by Faraday under EPA SBIR funding, with some input from academic and government laboratory sources for plating chemistry development. As we presented the data at technical conferences showing the demonstration of feasibility, we began to garner interest from OEMs such as The Boeing Company and depot-level maintenance communities within the Department of Defense. Such interest is vital to furthering technology development, by better understanding the industrial and military needs with respect to testing requirements, as well as implementation restrictions. We obtained funding through a government/industry consortium, the National Center for Manufacturing Sciences, to pass some general tests that needed to be passed to show the functional performance of the coating. During this program, we determined that there are also specific tests for each application, e.g., aerospace versus automotive, and within each application, tests that are specific to each entity, e.g., from one OEM to another and the various services within the Department of Defense. These specific technical hurdles needed to be passed before additional interest, and funding, could be obtained. Furthermore, realizing that plating industry sales are made mostly through chemical vendors, we identified and partnered with a vendor, Coventya, that has the requisite market channels and expertise to sell our trivalent chromium plating process. Coventya is working with us to stabilize the bath chemistry and determine bath lifetime and reliability. We recently began working on a US Army program for an expanded testing matrix working on a fully REACH-compliant trivalent chromium plating chemistry, developed in conjunction with Coventya, that does not contain boric-acid. Acknowledgements: This study is supported by the US EPA SBIR Program (EP-D-11-044), the US Army (W911NF-11-2-0014) and private sources. The financial support of Faraday Technology, Inc. corporate R&D is also gratefully acknowledged.

Manufacturability and Reliability Screening of Lower Melting Point, Pb-Free Alloys Containing Bismuth

This paper explores the manufacturability and reliability of three Pb-free Bi-containing alloys in comparison with conventional SAC305 and SnPb assemblies. The first alloy included in the study is a Sn-based alloy with 3.4%Ag and 4.8%Bi, which showed promising results in the National Center for Manufacturing Sciences and German Joint projects. The other two alloy variations have reduced Ag content, with and without Cu. BGA and leaded components were assembled on medium-complexity test vehicles using these alloys, as well as SAC305 and SnPb as baseline alloys, for comparison. Test vehicles were manufactured using two board materials, 170°C glass transition temperature (Tg) and 155°C Tg, with three surface finishes: ENIG, ENEPIG, and OSP. The accelerated temperature cycling (ATC) testing was done at −55°C to 125°C with 30-min dwells and 10°C/min ramps, for 3,000 cycles. Detailed microstructure examination before and after ATC testing is described, as is failure analysis. All three experimental alloys showed excellent performance in harsh-environment thermal cycling. Vibration testing at two G-force test conditions with resistance failure monitoring was performed on the daisy-chained components. A detailed description of the technique for the vibration testing using 2 G and 5 G harmonic dwells is provided. The lowest failure rate found at both the 2 G and 5 G levels was for the Cu-containing alloy known as Violet. These results provide data for further statistical analysis leading to the choice of proper combinations of the solder alloys, board materials, and surface finishes for high-reliability applications.

Environment-Friendly Electronics: Lead-Free Technology

Environment-Friendly Electronics: Lead-Free Technology

The Development and Commercialization of Lead-Free Soldering

Early in the 1990s in the United States, a series of legislative measures were proposed for banning the use of lead for many applications in industries involving electronic solders. Although electronic solders were ultimately exempted, this argument ignited worldwide concern, and research began on the development of lead-free solders. The U.S. project, organized by the National Center for Manufacturing Sciences (NCMS), was carried out from 1992 to 1996. Major electronics companies and auto manufacturers participated with several national institutes in this project.

Looking for Leaks in all the Small Spaces

This article describes use of photoacoustics by automakers to track and tackle leakage problems. Photoacoustics uses momentary heat from a light source to excite acoustic waves. Laser Imaging Systems of Punta Gorda, FL, developed the idea of photoacoustic leak detection. Dowling worked with Ford in developing leak localization as part of a team that was put together by the National Center for Manufacturing Sciences. Once a leak is sensed, a technique originally developed for a US Navy underwater acoustics program deploys to pinpoint its place. Vertical location is known already. Vacuum Instrument and Laser Imaging Systems are building the alpha prototype now.

The Information Specialist Customer Partnership

“To make significant contributions at appropriate points in the research process, information specialists must be positioned for proactive service to their users” (Von Seggem p. 101). At the National Center for Manufacturing Sciences Manufacturing Information Resource Center, information specialists are part of their customer' s team and contribute valuable expertise, information, and skills. The synergy of this relationship will be illustrated by describing three projects where these knowledge workers collaborated with their customers. From this experience, these information professionals share recommendations for fostering the customer librarian partnership. In conclusion, the synergistic practices described are related to literature on the topic of librarian customer teamwork.

Solder flow on narrow copper strips

Various solderability tests have been developed over the years to quantify the wetting behavior of solder on metallic surfaces. None offer an exact measure of capillary flow normally associated with conventional plated-through-hole and surface mount soldering. With shrinking package designs, increasing reliability requirements, and the emergence of new soldering technologies, there is a growing need to better understand and predict the flow of solder on printed wiring board (PWB) surfaces. Sandia National Laboratories has developed a capillary flow solderability test, through a joint effort with the National Center for Manufacturing Sciences, that considers this fundamental wetting issue for surface mount technology. The test geometry consists of a metal strip (width, 8) connected to a circular metal pad (radius, rc). Solder flow from the pad onto the strip depends on the geometric relationship between 8 and rc. Test methodology, experimental results, and validation of a flow model are presented in this paper.

Electrically conductive adhesives for surface mount solder replacement

Electrically conductive adhesives offer a lead free, relatively low temperature process for attachment of surface mount components to printed circuit boards (PCB's). The National Center for Manufacturing Sciences (NCMS) Conductive Adhesives project has defined a requirement for an isotropically conductive adhesive (ICA). In this study, 25 commercially available silver-filled epoxies were evaluated for joint resistance stability on copper and tin/lead surface finishes after 500 h of 85/spl deg/C/85% RH aging. Mechanical properties were evaluated through lap shear and impact testing. This testing led to a set of requirements for a surface mount adhesive including a volume resistivity of 1 m/spl Omega/-cm, less than a 20% shift in resistance after aging, and the ability to pass six drops with a plastic leaded chip carrier (PLCC) 44 package from a height of 1.52 m (60 in). Promising candidate adhesives identified in the screening study were evaluated on a circuit board test vehicle with a variety of components. Assembly revealed a narrow processing window when compared to solder. Impact testing demonstrated that current materials have inadequate impact strength for many components and accelerated T/H aging reveals unstable electrical resistance with Sn/Pb finished components. Preliminary data is included on a new adhesive formulation that has been developed to address the shortcomings of currently available ICAs.

Application Model for Organic Solderability Preservatives

Organic solderability preservative (OSP) coatings are not new. They have been used successfully with aggressive water soluble flux for assembly of through‐hole only PWBs. However, the multiple heating cycles required for mixed technology assembly and use of no‐clean low solids flux (LSF) for wave solder assembly have placed a greater demand on the solderability protection provided by OSPs. Wetting balance and float testing were used to evaluate numerous OSPs as well as the potential for these surface finishes to be used for ‘No‐Clean’ assembly. Although these laboratory evaluations revealed that OSPs are not as robust as SnPb, they did indicate the assembly processes and materials which could work with OSPs. Additional simulated assembly trials with test vehicles confirmed that thick OSP pre‐flux coatings interfere with soldering and that the solderability of surfaces with thin OSPs degrades when heated in an air environment. Since none of the OSPs evaluated outperformed the imidazole currently in use at AT&T, a no‐clean LSF assembly production trial with a mixed technology telecommunication circuit pack was conducted to compare imidazole with hot air solder levelled surfaces. The production trial and laboratory evaluations resulted in the development of an application model. The elements of the application model are not complicated: (1) use thin OSPs, (2) avoid baking, (3) use as aggressive a flux as possible, (4) apply as much flux as possible, (5) apply the flux where you want solder to wet, and (6) use nitrogen inerted processes whenever possible. Combination of these elements has led to the successful implementation of OSPs for no‐clean assembly. Funding for this effort was obtained through the National Center for Manufacturing Sciences (NCMS) Printed Wiring Board Interconnect Program.

Hitting the road with manufacturing know-how (education)

The mobile Manufacturing Technologies Laboratory (MTL), a program that takes technology education to students, is described. The program was introduced by the National Center for Manufacturing Sciences (NCMS) consortium, a public and private partnership whose goal is to improve US competitiveness through collaborative R&D, in 1992. Twelve modules have been developed: CAD, CAM, computerized numerical control (CNC), robotics, lasers, logos, packaging, biosphere, habitat, structures, anthropometry, and time.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Federal Regulations Create New Challenges in Materials Science

Title 40 of the Code of Federal Regulations is a compendium of rules pertaining to environmental protection, written primarily by the Environmental Protection Agency (EPA). These environmental regulations stand some 19 inches wide on a library shelf and are enclosed by 15 volumes of everchanging information. Each of these volumes contains amendments made to the rules since the last publication of that volume, so the effective dates of new regulations can be difficult to ascertain. Interpreting certain regulations has been difficult for many, the cost of complying with them high, and the eventual impact on the national economy foreseen as gloomy. Few, however, would deny the benefits of a well-planned environmental protection plan and few would sympathize with private corporations that flagrantly ignore regulations, pollute their local environment and, when identified, sustain heavy fines from the EPA.With problems like acid rain, air and groundwater pollution, global warming, ecological system degradation, municipal, industrial, and nuclear waste (and the federal regulations designed to control them), the need for important materials science research and development is great. These opportunities can be compared in magnitude with those provided by the Manhattan Project, during the 1940s and 1950s, and by the semiconductor revolution in later years. The difference between these past projects and the current situation is the way in which funds are appropriated for the research and how the work is performed. Rather than independently funded research performed by multiple organizations, work on environmental problems is witnessing cooperation among industry, government, academia, and the public, with a consequent savings of research monies. This cooperation is often achieved with a consortium of organizations such as SEMATECH or the National Center for Manufacturing Sciences.

Plasma-sprayed coatings as adherend surface pretreatments

As part of the National Center for Manufacturing Sciences contract on adhesive bonding of dissimilar materials, UTRC, as a sub-contractor, is evaluating environmentally acceptable surface preparation techniques for selected metals and composites. The selected processes are automatable and capable of being transferred into the manufacturing arena. One aspect of the programme is the evaluation of plasma-sprayed, microporous, thin coatings as surface pretreatments for both resin-based composites and metals. Mechanical test results are presented which demonstrate the viability of this approach to achieve acceptable joint strengths with steel, titanium and aluminium bonded to several types of resin-matrix composite. The environmental impact, by elimination of organic primer systems and strong acid etching and anodizing solutions, will be discussed.

Accelerating Technology Transfer in R&amp;D Consortia

Since the passage of the National Cooperative Research Act in October 1984, more than 150 R&D consortia have filed with the U.S. Department of Justice. Some of the more prominent U.S. consortia are the Microelectronics and Computer Technology Corporation (MCC) and SEMATECH in Austin, Texas, the Software Engineering Institute in Pittsburgh, Pennsylvania, the National Center for Manufacturing Sciences in Ann Arbor, Michigan, the Semiconductor Research Corporation in Research Triangle Park, North Carolina, the Biotechnology Research and Development Corporation in Peoria, Illinois, the Software Productivity Consortium in Herndon, Virginia, and the Center for Advanced Television Studies in Boston, Massachusetts. These consortia cover a range of emerging technologies including telecommunications, microelectronics, semiconductor manufacturing, biotechnology, software engineering, transportation, and superconductivity. They are composed of 1,157 business, government and academic organizations. Data on 902 of the business organizations in the IC(2) Institute's consortia database shows that 843 are U.S. companies and 42 are foreign firms. The balance are state and Federal government agencies, U.S. and foreign universities, and other consortia. The table below lists the U.S. firms involved in six or more consortia. While consortia vary in organizational structure, technological emphasis, funding mechanisms, and personnel make-up, they all share one abiding issue which relates to their purpose for being formed the transfer of technology to their member companies in an efficient, timely manner. Technology transfer is the application of knowledge. It involves any geographical shift of technology (ideas as well as physical products): person-to-person, group-to-group, or organization-to-organization. There are two fundamental aspects to the transfer process. First, the technology must be created or discovered. Second, it must be expeditiously transferred to and used by the appropriate receptor. The second aspect is proving to be at least as challenging and certainly more controversial than the first. R&D consortia pose unique management challenges and they represent a new type of organizational form for several reasons. Consortia are often composed of companies (i.e., shareholders) that seek mutually beneficial cooperative research while remaining competitors in the marketplace. They are thus often composed of personnel from radically different corporate cultures. In addition, shareholder members present different managerial priorities, policies and procedures. As a result, companies often participate in a consortium for different and sometimes conflicting reasons. Within any single consortium, different research programs, utilizing different research methodologies are commonly being pursued simultaneously. Consortium managers and researchers are thus separated from shareholder organizations by a variety of professional, technological, strategic, and cultural barriers. Although they may be less pronounced, similar barriers to technology transfer exist between the R&D laboratory and the production and marketing departments of a single firm, or between corporate R&D and a firm's divisions. This paper takes the position that lessons learned about technology transfer in a consortium are important for firms trying to effect the timely transfer of technology from the research bench to the marketplace. These lessons provide useful insights on practical ways to speed technology transfer across the functional departments of an organization. Methodology An applied management model for technology transfer has been developed from a year-long study of the Microelectronics and Computer Technology Corporation (MCC), a major, for-profit, U.S. R&D consortium that was established in 1983. From January to May 1989 in-depth interviews were conducted with managers and scientists at the consortium and with shareholder representatives. …