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60 SMT Magazine • May 2014 PCBa TEST: ENaBLING THE RIGHT maNaGEmENT PRaCTICE continues feATuRe Ability to review production and test data OEMs also expect their CMs to work collab- oratively with them to improve design for test- ability (DFT) prior to high-volume manufactur- ing. Lack of manufacturing test expertise at OEMs OEMs may not have planned an appropriate DFT or test methods early enough, causing their CMs to face challenges of lower yield during the high volume manufacturing phase. Lack of sensitivity to CMs' automation needs OEMs may not understand the cost and de- sign challenges faced by the CMs in deploying automation. Implications of These Challenges There is a critical need for contract manu- facturers to rise up to these various challenges, because they can impact their own costs consid- erably. In previous business models, CMs could negotiate with their OEMs to identify the test strategy and charge them appropriately for each test process. In the new model, today's OEMs often declare that CMs manage these costs and drive quality-oriented goals at functional test. In such scenarios, if the test strategy has not been well defined, it would lead to addition- al cost burdens. For example, if in-circuit test access has not been catered for at the design phase, the dependency would be on functional test, which would not give the level of diag- nostics needed to improve the process or repair the boards. On the other hand, OEMs may also face more challenges, especially with time-to- volume and time-to-market, as they cannot get quality boards to flow through, thereby in- creasing costs at final assembly. Any undetected defects can also flow to consumers, which can have negative impact to revenue and loyalty. The overall cost to produce a printed circuit assembly comes from the cost of components, cost of manufacturing, and cost of test. It is crit- ical for OEMs and CMs to achieve profitability and quality through design for testability. En- abling the right test technologies to ensure ac- curate diagnosis can not only identify product failure, but also process failures. While there is a figure 1: A variety of defects and variables that are tough to control.