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76 The PCB Magazine • July 2017 to design. Dennis presented a couple of key def- initions as it relates to this interaction: • Reliability: the ability to function as expect- ed, under the expected operating conditions, for an expected period, without exceeding expected failure levels. • Quality: the ability to produce the prod- uct, in the manner specified by the customer in the documentation package provided, includ- ing any test or legal requirements. A review of the traditional evaluation meth- ods was discussed, followed by an examination of both the strengths and shortcomings of tra- ditional methods. Dennis discussed the reliabil- ity challenges of today's technology, including component miniaturization, additional assem- bly thermal cycles, lead-free temperature re- quirements, and the increased stresses placed on laminates. He concluded that while tradi- tional PWB quality measurements are still nec- essary to keep fabrication processes in control, development of new measurements is needed to assure reliability of advanced technology. Physics of Failure Craig Hillman, Ph.D., CEO and managing partner of DfR Solutions, presented a briefing on the IPC committee work regarding the need to develop modeling and simulations for phys- ics of failure (PoF) requirements. Craig cited in- creasing interest from OEMs is driving the sup- ply chain to perform these type of analyses, and the industry has a general lack of data in these areas. Craig defined the scope of the problem when he stated, "When product volumes easily run into the millions of units, even a 0.1% fail- ure rate problem is a large issue." An interest- ing point was made when he presented the rea- sons that OEMs "hate" environmental testing, including: it takes too long, costs too much, is too late in the process, suppliers rarely fail their own testing, failures are not always relevant, and there is significant disagreement over what failure means. The scope of the committee work is to iden- tify best practices in the practical implementa- tion of requirements for physics of failure anal- ysis from the electronics supply chain, with a specific focus on component and assembly technology. Craig shared comments from a ma- jor PCB fabricator, who stated, "New, upfront methods of modeling must be developed and implemented to increase the ability to quickly discover and correct issues in designs to avoid latent field issues, reduce warranty costs, and increase customer satisfaction." The goal of the committee is to review the current 20+ stan- dards and leverage the appropriate attributes to develop a new standard to meet the existing ex- pectations of the industry. Voids in QFN Solder Joints: What should we use for maximum void criteria? Dave Hillman, principal materials and pro- cess engineer with Rockwell Collins, present- ed on the impact of voids in solder joint reli- ability. Dave began with a review of packag- ing trends, including cost, low profile, electri- cal performance and thermal dissipation. He then moved on to reviewing the design impacts on solder joint performance, including assem- bly influences such as solder paste choice and reflow profile. A frank discussion followed re- garding the "functionally vague" guidance on acceptable voiding, and the decision to devel- op a new acceptability criteria that is based on industry data leveraging the work done by the NASA DoD Consortia Team. Dave reviewed the test vehicle and components, thermal profile and testing protocol that was developed and re- sults of the reliability tests performed. The con- REVIEW OF THE 2017 IPC RELIABILITY FORUM Figure 6: Jack Fisher and others discussing the importance of manufacturing high-performance products.