1.2 The Development of Green Design and Manufacturing Competency

One of the most difficult steps in the initiation of a green product development strategy is where to get started. The green knowledge base for product development is widely distributed and not readily available within the organization, in the design or process teams. The supply base has varying degrees of experience with green methods and processes. Several alternatives are available to bring this knowledge into the company: Groom the individual(s) within the organization, hire an experienced green professional away from another organization or competing company, or engage consulting services. Each alternative has its own benefits and drawbacks.

Internal green competency development takes time, and the choice of the individual(s) is very important. There are two elements to the green competency: One is the knowledge of the regulations, be they local, national, or international. The other is the knowledge of the process steps, the chemistry, and analysis tools required to evaluate the material properties for hazardous materials and their proposed green replacements. Several larger companies have opted for at least two required skill sets — one individual for regulatory and coordination with the appropriate agencies and another for material and chemical knowledge. The former could be an individual in the process, regulatory, or quality departments, while the latter could be a highly educated expert in materials as well as complex analysis methods. The majority of companies will probably choose one individual whose skills combine a mix of the two characteristics. However, this dual-skilled individual will be dependent on outside experts and their points of view when forming his or her opinions on green alternatives. That person might have difficulty wading through claims of competing trends in industry. In addition, he or she may have limited capability in undergoing extensive testing and analysis of green alternatives. In most cases where the company started with the two skill set model, one of the two will eventually leave the company or take on a different position internally.

Hiring away an expert from another organization or a competing company can benefit the company in the short term by quickly getting access to the individual's knowledge of green design and techniques. However, the company has to be cognizant of the individual's previous set of skills before she or he acquired the green knowledge and whether that is compatible with the company's future needs. As the green set of skills permeates the company's organization, the need for the green expertise of this individual will diminish, and the company might have to place this individual in a new position, where his or her previous skills could be useful for both the individual and the company. Hiring a consultant or consulting services is very beneficial in two aspects: it is a quick method to obtain information and build the green competency, and it is also temporary, since the services are provided for a fixed time and there is no long-term commitment to the consultant. However, the drawbacks could be substantial and are listed below:

• The consultant might not be really up to date with green regulations or green process and material selection. A few questions could clarify the currency of the consultant's knowledge.

• The company should be wary of consultants recommending quick and easy green solutions: Do they have a personal stake in the materials or processes recommended? What is their association with the source of the recommended solution? Are there any hidden patents or copyright issues with their recommendations? Have they participated in studies sponsored and paid for by particular green suppliers? Have they declared all their prior or current associations with any supplier?

• Consultants deal with today's state of the art in green technology. In any new developing technology, the rate of innovation and research is high. Suppliers of green material and processes are constantly improving their products and can quickly leapfrog the performance of their competitors' materials. Thus the company will constantly have to go back to consulting services to keep ahead of technology or develop its own internal competency.

A mix of these strategies with short and long-term goals could be the best solution to the green competency challenge. The most important element is the planning stage, in order to devote enough time to formulate the appropriate green strategy and then form the green implementation team and key personnel to staff it.

1.3 Green Design and the New Product Life Cycle

In focusing on green design and manufacturing, it is important to understand the latest trends in the new product development cycle. The revolution in the high-technology industries has shrunk the product design and use life cycles to a period of weeks and months through concurrent engineering. At the same time, traditional design and manufacturing cycles in electronics circuits, tooling, and packaging had to be modified or outsourced to keep pace with new and lower-cost product introductions. The design team has been extended through the ubiquitous Internet to include collaborative activities within the company, its customers, and its suppliers.

The major premises of concurrent engineering have mostly been achieved, in terms of faster time to market, collocation of the various product creation team members to increase communications and feedback, and the use of design and quality metrics to monitor and improve the design process. The challenge is how to maintain and improve these gains and introduce green design and manufacturing at the same time by leveraging the trends in the globalization of design and manufacturing resources, and the wide use of the Internet as a communication tool.

The product realization process has undergone several changes with the advent of concurrent engineering. The change from a serial process of product development to a more parallel process has resulted in the need for new paradigms. Clearly, the impact of these new products is very critical, as indicated by vintage charts at different companies. In many high-technology companies, 70 percent of the total revenues of the company come from products introduced during the last few years.

Traditional product development required a top-down control of the various activities of product creation. Very formal organizational structures were developed and managed with a phase review process. Plans and milestones had to be completed at the end of each phase of product development and were subject to several levels of management reviews. After each review, the project was allowed to proceed and be funded until the next review.

The pressure toward shorter project time frames, global teams, quality and design, and manufacturing outsourcing have resulted in significant changes in the relationships between the company personnel and their suppliers with more frequent communications occurring earlier in the product development cycle. These suppliers and their own subsuppliers are called the supply chain.

1.3.1 Green Supply Chain Development

The major supply companies have mimicked the reach of the original equipment manufacturers (OEMs), by distributing their manufacturing centers globally, to be near their customers' sites. In this manner, supply companies can service global OEMs. The issues of global supply chain can be summed up as follows:

• The OEMs are forcing their suppliers to conform to their design specifications. For example, most OEMs will specify that the design and manufacturing documentation from suppliers conform exactly to their in-house CAE/CAD systems, including the system type and model number. In addition, OEMs can specify certain green materials and finishes and force the suppliers to produce them.

• The OEMs are also asking their suppliers for production quality verification, such as final testing, including troubleshooting of their products and systems. This could include reliability and quality testing of new green materials such as adhesion and pull tests of lead-free soldering by the suppliers, as well as certification of compliance with regulatory bans of hazardous materials (due diligence).

• Increased dependence on supplier quality and lower-cost goals has resulted in eliminating inspection for incoming parts by the company and shifting the burden to the suppliers, making companies vulnerable to spurious quality problems in the supply chain and increasing the need for due diligence on banned non green substances and materials.

• The trend toward increasing the links in the supply chain by further subcontracting to achieve even lower-cost manufacturing has resulted in low-technology suppliers getting into the manufacturing cycle for high-technology products. These suppliers do not have the sophisticated technology or the controls in place to make sure that all necessary specifications are inspected and variances in quality are promptly reported up the supply chain. For an OEM, a poorly managed supply chain is vulnerable to quality problems if changes are made in the subcontractor chain without the OEM's approval or notification. It is recommended that the supply chain not extend beyond three levels down from the final assembly.

• These low-technology suppliers represent a greater risk to the green supply chain. They tend to be unregulated, with greater focus on cost than on quality or green. They might purposely substitute specified green materials, which might be more expensive, with nongreen components or processes. A very effective system of quality and due diligence has to be in place to prevent this tendency. Recent examples of pet food and toy finish poisoning from China show the large negative impact of unregulated foreign suppliers.

• The electronics supply chain is also performing warranty and repair of the customer products. For green products and processes, the repair process of electronic circuits has to be developed and tested, since these processes might have different characteristics from nongreen ones. Other chapters in this book explore how to develop and test repair processes for electronic circuits and PCBs.

The obvious concerns in adopting green materials and processes are the quality and reliability issues. In this book there are several chapters with many examples of case studies on how to properly test green materials and processes for quality and reliability, using either mathematical or physical environmental conditions to simulate life-cycle material behavior. These tests can be performed by either comparing the properties of green materials and processes to a baseline of nongreen materials, or to study the life cycle through testing to failures. These techniques will result in calculating a quantifiable risk level for green alternatives, or lack thereof.

Most of the green materials and process verifications in this book and in the general literature are based on the performance of the green materials, and not on the consequences of adopting new green materials on the functional performance of the products. New products can be based on either existing designs that have been converted to green or an improvement on the technology of an earlier generation of nongreen products. In the case of converting current products to green, some product performance verification tests will have to be repeated to ensure compliance with advertised specifications, especially when PCB designs are re-layed because of lack of green replacement components with the same footprints. In the case of newly designed green products, verifications tests will uncover any hidden problem when using fresh green materials and processes in the design.

While a company might perform a very thorough set of tests and analysis of green materials and processes, the green products using them might exhibit different functionality than expected in the nongreen predecessor products. Refer to Sec. 7.2 for more insight into the green material conversion consequences in design. These potential adverse consequences could be as follows:

1. Radio-frequency (RF) and wireless circuits. These circuits are susceptible to changes in the shielding provided by changes in the metallic or plating of shield metals (such as the removal of hexavalent chrome coating) or by changing of the PCB surface finish [from tin lead hot air solder leveling (HASL) to immersion silver, for example]. These new green materials might cause a frequency shift in the tuners of these circuits. This is especially serious if there are no adjustments available to tune the RF or wireless oscillators. Redesign or relayout of the electronics circuits might be required.

2. Clock speeds and propagation delays. In very high speed circuits, clock speeds and propagation delays through the electronics circuits and components might be affected by changes to the surface finish of the PCBs or to the materials used in the interconnecting traces on the outer layer surface and through the inner layers of multilayer PCBs and connectors. Electronic race conditions might also be increased due to these conditions.

3. Transmission line reflections. When the electronics on the PCBs are connected directly to outside connectors or to other PCBs or products in a digital communications mode, the impedance match between them is very critical to sustain digital transmission over specified connector cable lengths. Changes to green materials might offset this impedance balance, rendering communications less effective. The communications system might work for shorter distances than specified, engendering a serious customer satisfaction issue. A simple PCB test would be the standard Time Domain Reflectrometry (TDR) test, where a coupon with a specified parallel trace length is used for the PCB laminate to ensure transmission line conformance to specification. This test can be performed at the PCB fabricator location and specified as part of the quality audit.

4. PCB surface features: In some electronic designs, PCB surface features are used for electrical, magnetic, or charge coupling in the electronics circuits. Examples would be the use of filled-in surface pads or rings to generate proportional feedback for a position control circuit. Changing the PCB surface finish to green materials might change the electrical or electromagnetic properties, rendering the circuit inoperable or out of control.

5. Surface resistance and cleanliness: With new green materials for soldering and fluxing of electronic PCBs, the cleanliness properties of the PCB after soldering or reflow might change. These changes can be easily measured with a variety of instruments such as surface insulation resistance (SIR) meters.

1.5 Implementing a Successful Green Design and Manufacturing of Products, Using Quality Tools and Techniques

The conversion of electronics manufacturing processes to comply with RoHS regulations provides a great opportunity of process improvement for efficient as well as environmentally friendly design and manufacturing processes. Six Sigma and quality techniques for process measurement, analysis, and improvement can be used to select optimum RoHS-compliant processes that will increase quality and reduce cost. The methodologies outlined in this section were used by the New England Lead Free Consortium of companies created by the author and jointly supported by funding and resources from member companies, the Toxics Use Reduction Institute (TURI), and the EPA.

An unintended consequence of the RoHS directive began when the components suppliers implemented their RoHS compliance by eliminating banned substances such as lead in the component finishes. As a result, some suppliers decided not offer the components with the original lead finishes, since they did not want to keep two versions of the same component. The exempted industries are finding that they cannot easily obtain their traditional leaded components and therefore are being forced to make necessary changes to their components and processes to be RoHS-compliant. It appears that an unintended impact of the RoHS regulation is a universal switch away from the banned substances for all industries, giving all companies the opportunity to make optimum material and process improvements as they switch into new materials and processes because of RoHS compliance.

Implementation of RoHS offers several opportunities as well as dilemmas for companies. This is because of the myriad alternatives being proposed by their suppliers with conflicting claims, as well as the pace of technological progress in material technologies. What is a hot RoHS material substitute today might become out of favor because of subsequent developments. Examples include such developments as bismuth-based solders, which were attractive because of their lower melting temperature that have fallen out of favor since they have contamination problems with lead, while tin-based solders and finishes were suspect as lead-free replacements because of their higher reflow temperatures and the dreaded tin whiskers. In addition, technological developments in material technology, as in any other, tend to produce leapfrog effects: a supplier that claims to have the best results for their materials might be overtaken by another supplier with a newer technology. So what is a company to do that is trying to implement RoHS?

The larger companies developed their own research program, with a multitude of talent and resources brought to bear, to solve the problems of material and process conversion for RoHS compliance. They might work with their contractors and material suppliers to implement RoHS compliance using a variety of reliability and test methods, as well as complex analytical tools such as vibration platforms, long-term environmental testing to failure, and electronic scanning microscopes to see the interfacing layers of RoHS-compliant materials. These sophisticated analysis tools and extensive DoE matrices were used to evaluate a large number of candidate material replacement and process parameters.

Medium and smaller companies could not afford these massive programs, but could develop cost-effective green conversion programs using Six Sigma principles for RoHS conversion projects. A set of simple guidelines to effectively manage a successful conversion could be as follows:

1. Avoid the NIH (not invented here) syndrome. There are many resources available for identifying successful materials and process replacements for RoHS-prohibited materials. These include national consortia and standards-setting organizations for electronic products such as NEMI, SMTA, and IPC. However, these organizations might recommend the general composition of the replacement materials, but not the specific process parameters to handle the local complement of equipment and product mix that the company uses.

2. Use standard performance criteria and test methods for the RoHS materials whenever possible. Standards for reliability testing using temperature and humidity cycling, vibrations, electrical conductivity, and mechanical stress exist for many materials from the same sources mentioned in the preceding paragraph. In addition, use testing methods that are standardized in industry, either by using techniques that are outlined in the standards or using commonly available commercial testers to perform the test.

3. When standardized or commonly used testing methods are not available, the current processes could be used as the baseline when comparing RoHS-compliant materials to the current process. Comparing to the baseline can also be used when there is not enough time or resources to properly conduct the testing for the RoHS materials. This could be the case for shorter-term environmental testing. Examples would be to use fewer temperature cycles and not test to failure, but to compare pull tests of RoHS materials to baseline leaded counterparts. Vibration testing could be on specific spectrum lines and not the full spectrum of frequencies. Statistical significance testing could be used to compare lead-free results to the current product leaded manufacturing process baselines.

4. Use the latest green material selection available, from leading material suppliers, realizing that today's RoHS material champion might not be the champion tomorrow, and that the tests might have to be repeated down the road as the material technology keeps improving. Avoid proprietary or patented materials.

5. Realize that the RoHS conversion effort might not be performed in one single large continuum project, but might be a succession of smaller projects that builds on the knowledge acquired in the previous project. For example, in lead-free soldering, there might be an initial project to deal with SMT components, with a distinct portion for BGA/mini BGAs, and then follow on projects for through hole and rework.

Research efforts for RoHS conversion by the New England Lead Free Consortium of companies and academia, which was created by the author, began in 1999 and continue today. The research followed the broad guidelines outlined above. The concerns for RoHS conversion were focused on three parts: reliability, quality, and manufacturability. The RoHS-compliant alternatives had to meet and/or exceed current nongreen materials and processes in terms of reliability; they should be able to produce virtually defect-free products and be implemented in a typical manufacturing process line with standard machines and processes, including repair and rework.

The projects conducted for the lead-free conversion are comprised of four major phases to date, with each phase taking about 2 years. The lengthy time is due to the consensus needed to be achieved by the consortium members, and the funding requirements, as most materials and actual manufacture and tests were donated or performed by member companies, on a voluntary and pro bono basis. More information, including papers published on these projects, could be obtained from the author or the TURI website at www.turi.org. More detailed information on these phases is available in the next chapters, showing the technical background and reasoning behind the decisions made.

The phases were as follows:

1. Feasibility (phase 1). During this phase, the feasibility of lead-free soldering was explored as a viable alternative to leaded solder. The goal of this phase was to provide knowledge on the major issues of lead-free implementation during that time frame (1999 to 2001): What solder composition is the best alternative to tin/lead [(tin/bismuth, tin/silver/copper (SAC), and tin/silver]? What about the higher melting temperatures? Can the thermal energy to melt the solder be integrated in time to lessen the impact of the thermal shock on electronic components? Can a lead-free process deliver zero defects under controlled conditions?

Table 2.12 details the design of experiments (DoE) matrix for phase 1, showing the selection of 5 factors in 27 experiments. TAL refers to time above liquidus. The project material and process selection was limited to a small number of laminate and component finishes. The selection was also organized in a set of partial factorial experiments to lessen the time and effort involved. The reliability testing was performed through pull tests after 2000 typical thermal cycles of 0 to 100°C in 1-h cycles, and the number of solder defects was analyzed on a ppm (parts per million) basis, according to IPC standards.

The results were very encouraging. Reliability data (thermal cycling followed by pull tests) showed that the lead-free joints were stronger than legacy tin lead joints, and the quality data indicated that zero defects were possible with lead-free soldering in certain combinations of solders and PCB surface finishes. Manufacturability issues of thermal profiling were also shown to be of little or no significance.

2. Wide material selection (phase 2). In this phase, the experience gained from the first phase was used to narrow some of the choices such as the SAC solder formulation and a common thermal reflow profile, while the alternatives for laminate finish (5) and component type surface finishes (4) were expanded. Manufacturability concerns such as the use of nitrogen were also added. A full factorial experiment was performed to make sure that there was no confounding of interactions. A baseline of legacy tin lead finish components was also produced and compared to the lead-free alternatives. This experiment was much larger in scope and effort than the first experiment. The same reliability assessment of thermal cycling and pull tests as well as quality consideration of 100 percent visual testing according to IPC standards was used, in addition to some investigations of the inner metallic layers using SEM.

The results were very similar to those of phase 1, in that certain combinations of materials and processes produced near zero solder defects. Many of the factors were not significant in either reliability or quality testing. Figure 1.1 is a Minitab plot that shows the distribution of visual defects versus the selected factors of surface finish, solder suppliers, and reflow atmosphere. Subsequent analyses showed the selections of the finishes were not significant to one another in quality or reliability data.

An interesting subtest of the analysis was that under certain combinations of materials and processes, the quality and reliability of lead-free soldering were not affected by whether nitrogen was used in the reflow process. This is an important finding in terms of reducing the cost of electronics manufacturing.

3. Manufacturing process optimization (phase 3, also called TURI TV3 in Chap. 6). Building on the previous phase, the material and process selection was narrowed down to the successful candidates gleaned from phase 2, and then the project focused on simulating actual manufacturing conditions. A larger test PCB was manufactured, at the standard panel size of 16 x 18 inches as opposed to the 6 x 9 inches from phase 2.

Although a full factorial experiment was conducted, the total number of test PCBs that were analyzed was at 24 lead-free PCBs as well as 12 for a leaded PCB baseline, compared to 120 PCBs from phase 3. The testing performed was similar to phase 2, with the addition of vibrations and multiple reflows (to simulate rework and repair) to the mix. The reliability and quality results for surface mount technologies (SMTs) indicated that with the factor selection used, there were no significant differences between the lead-free and the leaded baseline PCBs in reliability as measured by the pull tests, and in quality, as measured by visual inspection. The significant differences in pull tests were in three areas: lead finish (tin versus tin-bismuth), pull direction (up or down, because of the location of the pull gage), and the interaction of laminate finish and laminate type (one of the two SAC solder suppliers performed significantly different with the three laminate types shown). Figure 1.2 is a plot generated by Minitab to show the various interactions present in the DoE of phase 3. Quality analysis showed a significant lower quality for through hole and rework conditions, necessitating a closer look at these conditions in phase 4, and recounted in Chap. 6 in this book.

4. Manufacturing and technology optimization extension (phase 4, also called TURI TV4 in Chap. 6). In this phase, the unresolved issues of phase 3 were further investigated. These include the through hole technology and the rework methodology. In addition, new materials that might be included in future green efforts such as halogen-free laminates are being investigated against a baseline of halogen-based materials. Similar efforts were undertaken to comply with RoHS requirements for other prohibited materials, including hexavalent chromium, done in the University of Massachusetts Lowell in association with Tyco Electronics. Several alternatives were examined, and a replacement chart for each application was generated based on extensive testing in harsh environment, all meeting company and industry standards. This successfully concluded project followed the general guidelines given above.

In conclusion, the RoHS conversion process for prohibited materials is an excellent opportunity to examine the material replacements and their manufacturing processes and to apply Six Sigma and quality principles to improve quality and lower manufacturing costs.

Excerpted with permission from McGraw-Hill Professional from Green Electronics Design & Manufacturing by Sammy G. Shina (McGraw-Hill Professional, 2008).

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