When Staples customers stop visiting the store or buying certain products, the company notices immediately (through the membership card described above). It then calls defectors to get feedback, and selectively discounts or targets its catalogs accordingly.
Zero Defect Quality.pdf
Understanding the economics of defections is useful to managers in several ways. For one thing, it shows that continuous improvement in service quality is not a cost but an investment in a customer who generates more profit than the margin on a one-time sale. Executives can therefore justify giving priority to investments in service quality versus things like cost reduction, for which the objectives have been more tangible.
Knowing that defections are closely linked to profits also helps explain why some companies that have relatively high unit costs can still be quite profitable. Companies with loyal, long-time customers can financially outperform competitors with lower unit costs and high market share but high customer churn. For instance, in the credit card business, a 10% reduction in unit costs is financially equivalent to a 2% decrease in defection rate. Low-defection strategies can overwhelm low-cost strategies.
Defections analysis can also help companies decide which service-quality investments will be profitable. Should you invest in computerized cash registers or a new phone system? Which of the two will address the most frequent causes of defection? One bank made a large investment to improve the accuracy of monthly account statements. But when the bank began to study defectors, it learned that less than 1% of its customers were leaving because of inaccurate statements.
A company that is losing customers because of long lines can estimate what percentage of defectors it would save by buying new cash registers, and it can use its defection curve to find the dollar value of saving them. Then, using standard investment-analysis techniques, it can compare the cost of the new equipment with the benefit of keeping customers.
Conversely, much of the information used to find defectors can point to common traits among customers who stay longer. The company can use defection rates to clarify the characteristics of the market it wants to pursue and target its advertising and promotions accordingly.
Many business leaders have been frustrated by their inability to follow through on their public commitment to service quality. Since defection rates are measurable, they are manageable. Managers can establish meaningful targets and monitor progress. But like any important change, managing for zero defections must have supporters at all organizational levels. Management must develop that support by training the work force and using defections as a primary performance measure.
The success of MBNA shows that it is possible to achieve big improvements in both service quality and profits in a reasonably short time. But it also shows that focusing on keeping customers instead of simply having lots of them takes effort. A company can leverage business performance and profits through customer defections only when the notion permeates corporate life and when all organizational levels understand the concept of zero defections and know how to act on it.
Trying to retain all of your profitable customers is elementary. Managing toward zero defections is revolutionary. It requires careful definition of defection, information systems that can measure results over time in comparison with competitors, and a clear understanding of the microeconomics of defection.
Just as the quality revolution in manufacturing had a profound impact on the competitiveness of companies, the quality revolution in services will create a new set of winners and losers. The winners will be those who lead the way in managing toward zero defections.
Today, assembly defects account for between 12% and 15% of semiconductor customer returns in the automotive chip market. As component counts in vehicles climb from the hundreds to the thousands, and quality targets shift from 10 dppm to 10 dppb, assembly engineers need to find practical means of delivering zero defective parts. Doing so puts greater demands on various process steps, including, metrology, inspection and test.
Historically, assembly factories have limited investment in process control and 100% inspection steps, partly due to lower process complexity and partly in order to maximize profitability. While final test can detect opens and shorts it is less effective at detecting marginal assembly defects that lead to reliability failures. Now, in order to meet the zero defects goal, assembly houses are ramping up 100% inspection capabilities, and investing in process control at key assembly manufacturing steps.
As each new fab and assembly technology enters the automotive sector, the challenge is to understand what defects need to be detected and what equipment parameters may impact defects. Learning from the feedback of downstream steps requires data, as well as a means to connect the data. Unlike wafer fabs, this traditionally has not been an area of high investment for OSATs.
Automakers are demanding 10 defective ppb limits across the whole spectrum of automotive ICs and single transistor/diode devices. Depending upon the semiconductor device type assembly processes differ. This article focuses on ICs that use wire bond and bump technologies.
From 28nm to 7nm, FCBGA is the predominate package technology because it offers the pin density required by larger SoCs. These packages introduce new assembly defects that may pass final test yet fail in the field. New defects involve white bumps, bump cracks, and bump-to-substrate joints, all of which have a reliability sensitivity that makes them high risk for non-detection at final test and failures in the field.
With their foray into newer assembly and fab processes, automakers have well-acknowledged trepidation. First, vehicles easily have a lifetime of 10 to 15 years, as opposed to the 2 years for consumer products, and 4 to 7 years for computers. Understanding of long-term reliability issues is largely theoretical. Second, these processes have yet to experience the harsh automotive environment, which can translate into varying long-term impacts for marginal defects.
Understanding the assembly process informs one as to where and when assembly-related defects are introduced. Conceptually, wire bond and BGA/FCBGA assembly processes need to singulate the die, attach it to a substrate, bond the die to the substrate, test the unit, and perform a final inspection.
Within each process, manufacturing defects can occur. Meeting automotive expectation of flawless products requires an investment in 100% inspection capabilities, and more advanced tests at final test. Broken contacts and shorts between contacts/wires are easy to electrically test. Marginal contacts, die cracks and delaminations (bumps/package substrate) all represent latent defects that will fail in a vehicle. Marginal contacts can pass electrical test, yet because of a poor intermetallic connection, subsequent rapid thermal cycling and vibrations will cause the connection to open at a later point in time.
With this data, assembly process engineers can apply FDC and SPC analysis, which are commonly used in wafer fabs, to improve the overall process. Inspection and metrology can inform on the quality of the connections, and thus provide feedback as to which process equipment parameters matter most. For wire bonds, inspection catches defects while metrology systems assess the loop height, width, lift, wire length, and position. In assembly processes, the challenge to reach 100% inspection requires high-throughput systems that can automatically and reliable identify random and systematic defects.
Final testFinal test does an excellent job at detecting gross defects such as opens and shorts. Toni Dirscherl, product manager for power and analog solutions at Advantest Europe, pointed to the typical tests that focus on assembly related properties/defects.
Final test can be performed at a range of temperatures. Some package defects can be easier to detect with a pin leakage test at cold temperature, due to the lower background current in CMOS devices. Yet the test budget may necessitate engineers finding a means to detect these at only one temperature.
Tracing root causes of failureTo reduce assembly defects causing automotive IC returns, engineers need to determine the root cause. This requires an understanding of failure mechanisms, in addition to knowing where the defect was generated. Connecting the defect to the point of generation in the various manufacturing steps data requires traceability.
ConclusionFor assembly facilities to deliver 10 dppb quality to their automotive customers, they need to learn from customer returns. This requires investment in assembly equipment data collection and traceability. Latent defects that become activated during the warranty period yet pass electrical test necessitates 100% inspection to screen for these failures.
The best chance for detecting defects on a part is with electrical testing, which entails wafer probe or final automated test equipment (ATE) in packaged form. Conceptually, if the part has been characterized thoroughly and built on a known technology with a low defect rate, then any remaining PPM-level failures can be captured at the electrical test step. Characterization depends on: 1) the design failure mode and effects analysis (DFMEA) being able to simulate all failure modes; 2) product engineers being able to test the parts to cover all customer mission profiles; and 3) with increasing software components in the parts, ensuring that data fidelity is maintained throughout.
If we are to consider a strategy to move the needle closer to a zero-defect concept, then several things must change from the way facilities operate today. Most of these legacy facilities are semi-automated or manual. This means that they fundamentally have a multitude of point solutions and disciplines to govern their quality standards. Simply put, they neither capture all the data needed to govern their processes effectively, nor analyzethis data in a manner that allows for speedy and effective feedback. Based on field returns and internal failures, we have seen how far this strategy can take us. It is unlikely that we will be able to breach the 1PPM barrier consistently without rethinking the process entirely. 2ff7e9595c
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