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80 SMT Magazine • November 2015 factors toward cost reduction and quality maxi- mization. In that context, this paper will exam- ine two specific engineering-process aspects of introducing a new PCB design into assembly manufacturing and the technical barriers to be overcome to make the processes as lean as pos- sible. The two engineering processes to be dis- cussed are: 1. Performing design-for-assembly (DFA) verification on a new product design, as early as possible in the product lifecycle, and in any case before transferring the design into manufacturing. 2. Preparing assembly-line machine library content for fast set-up. Before getting into the technicalities of the two topics and how they are related, it is worth first considering the business environment of PCB manufacturing. It is now about 20 years since PCB assembly manufacturing began to be outsourced in a major way, with the resulting rapid growth of the now well-known EMS and contract manufacturers. Before the outsourcing revolution, when design and manufacturing operations were generally vertically integrated, it was common to see CAD/CAM engineering processes being set up and maintained by elec- tronics OEMs, depending for their success on internally defined library standards, a specific and relatively narrow range of manufacturing processes, and plenty of in-house proprietary software to link it all together. By contrast, to- day's challenge is to take full advantage of the outsourcing opportunity, the choice, the flex- ibility, and the cost-competitiveness, without losing the advantage through engineering-pro- cess inefficiencies related to discontinuities in CAD/CAM software, data flows, and libraries between the customer (the design organiza- tion) and the suppliers (the manufacturers). To make matters worse, the typical manufacturer of today will serve dozens, if not hundreds, of design-customers, and the design organization may use dozens of EMS providers. This many- to-many interface between design and manu- facturing tends to drive engineering processes toward standardized "lowest common denomi- nator" workflows that are relatively manual, error-prone, and slow. These workflows are cer- tainly somewhat "standard", but they are far from lean, in terms of minimizing waste and maximizing consistency through automation. The two engineering processes described in this paper are specifically designed to enable a high degree of production-portability between a product's design organization and multiple manufacturing facilities and processes. Portability of DFA Design for assembly refers to the dimen- sional analysis of a PCB design to check its compatibility with the intended manufactur- ing processes. Figure 1 shows illustrations of two specific DFA analysis checks: one check- ing the pin-to-pad distances against the rules of the reflow process, the second checking component-to-component spacing against the access-requirements of the rework process. The variety of rules typically scales with the range of intended assembly and test processes, as well as the number of component types or combina- tions of component types. Now consider the DFA business process be- tween a designer and a manufacturer, as illus- trated in Figure 2. The designer has responsibil- ity for the definition of the product, whereas the manufacturer is the owner of the manu- facturing processes and the knowledge of their limitations relative to the characteristics of the products being manufactured. The designer's interest is to design the product so it is optimally manufacturable by the widest range of manufacturing suppliers. To be as lean as possible, the DFA validation STreAmLINING PCb ASSembLy AND TeST NPI WITH SHAreD ComPoNeNT LIbrArIeS arTIcLe figure 1: Two Dfa checks: pin-to-pad analysis (left), and component-spacing analysis (right).

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