In this chapter, the need for accurate estimates of cost and quality will be shown, especially for mature technology products. In addition, expected cost and quality levels can be used as design guidelines for product functional partition, design quality assessment, and material and process selection in manufacturing. Developing an accurate quality and cost model for new electronic products, specifically for printed circuit boards (PCBs) is important, since PCBs represent the major part of cost, especially for assembly and test requirements. The model should be used as early as possible during the design stage, and is based on the design and manufacture of the PCB assembly operations as well as the manufacturing line equipment selection and layout. The following aspects of the relationship between quality and cost will be explored:
1. The overall electronic product life cycle cost model. In Section 6.1, the generalized product life cycle is reviewed, outlining the different phases that products and technologies go through, and the relationship of cost and quality to each phase. The elements that make up each electronic product cost are outlined, and techniques for monitoring and controlling costs are shown. These techniques include developing cost models especially for the primary cost factors, which are the PCBs.
2. The quality and cost relationship. The relationship of quality and cost are explored in Section 6.2 through the quality loss function (QLF). Formulations and examples of this system are given, and its use in estimating the relative value of making products to target or reducing variability explored. In addition, the use of this function to set factory process targets is shown to be a trade-off of defect removal either in the manufacturing plant or at the customer site.
3. Electronic products cost estimating systems for PCB fabrication. In Section 6.3, the technologies used for PCB fabrication and assembly are reviewed and their costs are quantified based on their manufacturing operations and complexity factors. A cost model for PCB fabrication is presented with a case study. The cost and quality assessment has to be tempered by other factors such as design time and new product introduction impact.
4. Electronic products cost estimating systems for PCB assembly. In Section 6.4, several systems are examined for determining the cost of PCB assembly. These systems vary in their complexity, from simple PCB components* material-cost-based systems to the more complex quality-based cost models, including a cost and quality model to examine the tradeoffs in design and manufacturing. Defects generated by alternative design, manufacturing and test strategies can be examined and a decision made for the lowest-cost alternative. Each system is discussed with examples and case studies.