Andrew A. Shapiro

HOUSEHOLD WILLINGNESS TO RECYCLE ELECTRONIC WASTE - An Application to California

Electronic waste (e-waste) has become the main contributor of lead to landfills in the United States. Households also store large volumes of e-waste, yet little is known about their willingness to recycle e-waste. This article starts filling this gap based on a 2004 mail survey of California households. Using multivariate models, the authors find that gender, education, convenience, and environmental beliefs but not income or political affiliation are key factors explaining the willingness to drop off e-waste at recycling centers. A comparison of an ordered probit with a semi-nonparametric extended ordered probit model of the survey responses shows that the latter better predicts less frequent answers. The results suggest targeting public education programs about recycling at teenagers or younger adults and making recycling more convenient for older adults; moreover, e-waste drop-off centers should first be created in communities that already offer curbside collection programs for conventional recyclable products.

Developing Gradient Metal Alloys through Radial Deposition Additive Manufacturing

Interest in additive manufacturing (AM) has dramatically expanded in the last several years, owing to the paradigm shift that the process provides over conventional manufacturing. Although the vast majority of recent work in AM has focused on three-dimensional printing in polymers, AM techniques for fabricating metal alloys have been available for more than a decade. Here, laser deposition (LD) is used to fabricate multifunctional metal alloys that have a strategically graded composition to alter their mechanical and physical properties. Using the technique in combination with rotational deposition enables fabrication of compositional gradients radially from the center of a sample. A roadmap for developing gradient alloys is presented that uses multi-component phase diagrams as maps for composition selection so as to avoid unwanted phases. Practical applications for the new technology are demonstrated in low-coefficient of thermal expansion radially graded metal inserts for carbon-fiber spacecraft panels.

Towards model-based engineering of underfill materials: CTE modeling

Abstract Polymeric composite based underfill materials, with well-controlled coefficient of thermal expansion (CTE) are critical to flip-chip and other advanced high-density integrated circuit packaging technologies. The use of underfills beneath the flip-chip integrated circuits leads to an increase in reliability by reducing the strain on the solder bumps during thermal cycling imposed by the CTE mismatch between the chip and substrate. A fundamental understanding of the composite CTE of underfill materials is critical to the manufacture of high performance underfill materials and is critical to market expansion of flip-chip technology for high density packaging applications. This work presents a novel model for predicting the effective CTE of underfills and other polymeric composite materials by considering the effect of an interphase zone surrounding the filler particles in a polymer matrix. A microscopic model is also introduced for the volume fraction of the interphase as a function of filler concentration as well as filler–filler overlapping. The CTE model resolves several conflicts regarding the effect of filler concentration, filler size and filler–polymer interaction on the effective CTE of underfill and other polymeric composite materials. The results are demonstrated to be critical for accurate flip-chip reliability predictions based on finite-element and other modeling techniques.

How much e-waste is there in US basements and attics? Results from a national survey.

The fate of used electronic products (e-waste) is of increasing concern because of their toxicity and the growing volume of e-waste. Addressing these concerns requires developing the recycling infrastructure, but good estimates of the volume of e-waste stored by US households are still unavailable. In this context, we make two contributions based on a national random survey of 2136 US households. First, we explain how much e-waste is stored by US households using count models. Significant explanatory variables include age, marital and employment status, ethnicity, household size, previous e-waste recycling behavior, and to some extent education, home ownership, and understanding the consequences of recycling, but neither income nor knowledge of e-waste recycling laws. Second, we estimate that on average, each US household has 4.1 small (<or=10 pounds) and 2.4 large e-waste items in storage. Although these numbers are likely lower bounds, they are higher than recent US Environmental Protection Agency (EPA) estimates (based on narrower product categories). This suggests that the backlog of e-waste in the US is likely larger than generally believed; it calls for developing the recycling infrastructure but also for targeted recycling campaigns.

Adopting Lead-Free Electronics: Policy Differences and Knowledge Gaps

For more than a decade, the use of lead (Pb) in electronics has been controversial: Indeed, its toxic effects are well documented, whereas relatively little is known about proposed alternative materials. As the quantity of electronic and electrical waste (e-waste) increases, legislative initiatives and corporate marketing strategies are driving a reduction in the use of some toxic substances in electronics. This article argues that the primacy of legislation over engineering and economics may result in selecting undesirable replacement materials for Pb because of overlooked knowledge gaps. These gaps include the need for: assessments of the effects of changes in policy on the flow of e-waste across state and national boundaries; further reliability testing of alternative solder alloys; further toxicology and environmental impact studies for high environmental loading of the alternative solders (and their metal components); improved risk assessment methodologies that can capture complexities such as changes in waste management practices, in electronic product design, and in rate of product obsolescence; carefully executed allocation methods when evaluating the impact of raw material extraction; and in-depth risk assessment of alternative end-of-life (EOL) options. The resulting environmental and human health consequences may be exacerbated by policy differences across political boundaries. To address this conundrum, legislation and policies dealing with Pb in electronics are first reviewed. A discussion of the current state of knowledge on alternative solder materials relative to product design, environmental performance, and risk assessment follows. Previous studies are reviewed, and consistent with their results, this analysis finds that there is great uncertainty in the trade-offs between Pb-based solders and proposed replacements. Bridging policy and knowledge gaps will require increased international cooperation on materials use, product market coverage, and e-waste EOL management.

Understanding Preferences for Recycling Electronic Waste in California: The Influence of Environmental Attitudes and Beliefs on Willingness to Pay

Increasing stockpiles of electronic waste (e-waste) combined with low recycling rates are threatening human and environmental health because of the hazardous materials in electronic products. To date, however, little is known about household preferences for e-waste recycling alternatives. This study starts filling this gap. Our 2004 mail survey indicates that California households prefer “drop-off recycling at regional centers,” with “curbside recycling” a close second. A contingent ranking (CR) analysis shows that households are willing to pay approximately

Design and Evaluation of Bioepoxy-Flax Composites for Printed Circuit Boards

0.13 per equivalent mile per month to increase e-waste recycling convenience. Our results show that ignoring environmental attitudes and beliefs leads to biased estimates of the trade-offs households are making between cost and recycling convenience. A good understanding of these trade-offs is necessary for a successful recycling program. Finally, this article illustrates some of the strengths and weaknesses of CR, an underused technique for analyzing preference rankings.

Implications of Pb-free microelectronics assembly in aerospace applications

Printed circuit boards (PCBs) pose considerable occupational health risks during manufacturing and are a potential source of toxic hazards if improperly disposed at the end of their useful life. Indeed, base materials in current PCBs include epoxy resins, fiberglass, and brominated flame retardants. To improve the environmental performance of PCB manufacturing and disposal, we developed composite designs using a thermosetting matrix based on epoxidized linseed oil, melamine polyphosphate for flame retardance, and woven flax fiber for reinforcement. Analyses of our prototypes using IPC 4101A/24 specification for thick PCB laminates gave acceptable results for thermal, mechanical, and electrical properties, except for wet conditioning or water submersion. To improve moisture resistance, we treated flax fibers with sodium hydroxide and octadecyltrichlorosilane. We find that the improved bioepoxy-flax PCB design is a viable alternative to current PCBs; it has potentially lower environmental impacts, it is cheaper, and it has satisfactory thermal, electrical, and mechanical properties. However, additional improvements in moisture absorption properties may remain needed for commercial applications.

Computational Evolutionary Embryogeny

The commercial microelectronics industry is rapidly implementing Pb-free assembly strategies and it should be mostly Pb free within the next decade. This trend is driven by existing and proposed legislation in Europe and in Japan, which has already led a number of firms (including AT&T, IBM, Motorola, Hewlett-Packard, and Intel) to adopt Pb-free implementation programs. This is another sign that the microelectronics industry has become truly global. Following Moores law, progress in microelectronics is brisk but not uniform: in many cases, commercial industry is ahead of the aerospace sector in technology. Progress by commercial industry, along with cost, drives the use of commercial off-the-shelf parts for military and space applications. We can thus anticipate that the U.S. aerospace industry, which is not subject to foreign legislation, will, at some point, be forced to use Pb-free components and subsystems as part of their standard business practices. In this paper, we provide a snapshot of the commercial industry trends and how they may impact electronics in the aerospace environment. Impacts will be felt in the areas of reliability, assembly methods, cost drivers, supply chain selection, and alternative materials selection. In addition, we look at different strategies for implementation. The questions we address include the following: Should companies immediately embark on a program to convert all of their electronics to Pb free? Should they phase it in instead, and if so, over what time frame? Should companies try to comply with industry Pb-free standards? What requirements should flow down to subcontractors and component suppliers? Legislation is pending in a number of states that may affect these decisions and their timing. The U.S. Environmental Protection Agency, through some university programs, is examining the implementation of Pb free as well. Finally, we present data from a portion of a recent NASA project that focuses on finding suitable alternatives to eutectic Sn-Pb solders and solder pastes and on determining suitable processing operations in assembling printed wiring boards. The world is moving toward implementation of environmentally friendly manufacturing techniques. The aerospace industry will be forced to deal with issues related to Pb-free assembly, either because of the progressive scarcity of eutectic Sn-Pb solder or because of legislation. This paper provides insights into some of the key tradeoffs that should be considered.

Electronic Packaging Materials for Extreme, Low Temperature, Fatigue Environments

Evolutionary and developmental processes are used to evolve the configurations of 3-D structures in silico to achieve desired performances. Natural systems utilize the combination of both evolution and development processes to produce remarkable performance and diversity. However, this approach has not yet been applied extensively to the design of continuous 3-D load-supporting structures. Beginning with a single artificial cell containing information analogous to a DNA sequence, a structure is grown according to the rules encoded in the sequence. Each artificial cell in the structure contains the same sequence of growth and development rules, and each artificial cell is an element in a finite element mesh representing the structure of the mature individual. Rule sequences are evolved over many generations through selection and survival of individuals in a population. Modularity and symmetry are visible in nearly every natural and engineered structure. An understanding of the evolution and expression of symmetry and modularity is emerging from recent biological research. Initial evidence of these attributes is present in the phenotypes that are developed from the artificial evolution, although neither characteristic is imposed nor selected-for directly. The computational evolutionary development approach presented here shows promise for synthesizing novel configurations of high-performance systems. The approach may advance the system design to a new paradigm, where current design strategies have difficulty producing useful solutions.