Design007 Magazine

Design-Feb2018

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78 DESIGN007 MAGAZINE I FEBRUARY 2018 There is often quite a distance between the design engineer and the manufacturing/assem- bly engineer, which provides sufficient neces- sity for DFM/DFA check. An excellent design for manufacturing/assembly check helps iden- tify potential issues prior to production, when changes are not as costly. An efficiency check must also be considered, since it determines a product's time to market. Improvement here derives from efforts in two aspects: your design file preparation and the manufacturer's DFM/ DFA capabilities. Your design files should be as complete as possible. For example, a DFM engineer once told me that she had been busy generating coordinate files all day, because their custom- ers seldom provided them. Later, when cus- tomers were required to do so, her DFM check efficiency dramatically rises. Until now, DFM/ DFA checks provided by most EMS providers were manually implemented. But now, some advanced EMS providers use automatic DFM/ DFA systems, dramatically increasing effi- ciency. Our company utilizes the Valor DFM system. Component Availability During assembly, components play a key role in electrical functionality and connection implementation. Therefore, an assembler's ability to manage components directly affects the success of NPI. Component management is primarily com- posed by three aspects: component procure- ment, inspection, and storage. Component procurement is always regarded as a critical standard of evaluating an assembler's capabil- ity. Long-standing and stable cooperation with authorized distributors and providers must be guaranteed so that component availability can be ensured, along with competitive prices. Moreover, the purchasing staff should fully respect their customers' selections when spe- cific component distributors are designated by customers. Even components purchased from the most reliable sources should be carefully inspected prior to assembly. Tiny components require rigorous environment and storage conditions. Temperature and humidity are essential to the implementation of component performance and functionality. Sometimes, for the sake of low cost, many components are purchased, but not all are used, so the rest of the com- ponents need to be temporarily stored in the assembler's warehouse. Fabrication and Assembly Capabilities Fabrication: When qualifying a company's PCB fabrica- tion operations, the following items should be emphasized: Quality Grade The quality grade to conform to is a direct tool evaluating the quality of circuit boards because regulations compatible with concern- ing quality grade determine and affect all man- ufacturing details. Generally speaking, PCBs fabricated by reliable manufacturers will be built to IPC Class 2. Layer Count This aspect is often neglected because it tends to be taken for granted. A truly trustwor- thy manufacturer should be capable of pro- ducing boards whose layers range from one to many. Apart from single- or double-sided PCBs that are most widely applied, other layer num- bers should be available as well, especially for those whose products call for HDI and minia- turization. Substrate Material Substrate material determines board's tem- perature and strength. Manufacturers should be able to deal with different substrate materi- als including standard FR4, Rogers, Teflon etc. Your design files should be as complete as possible.

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