Yield management for increased profitability

This paper provides a detailed introduction to the combined application of three specific tools; Technology Audits, Complexity & Yield Analysis, and Statistically Based Test Coupons to dramatically improve both supplier and user profitability. These tools ensure that users make best advantage of the capabilities of their suppliers. And the combined data from these methods provides suppliers with information necessary to make better and more cost effective decisions regarding equipment, research and development (R&D), engineering and operator training investments. For users the methodologies presented produce a quantitative alternative (or addition) to traditional vendor management tools that rely primarily upon qualitative assessment of vendor capabilities in combination with tracking of quality and delivery performance. Users can also use these tools to more cost effectively allocate their designs to those suppliers whose combination of technical and cost capabilities best match the requirements of specific designs. Qualification of printed wiring board (PWB) fabricators by original equipment manufacturers (OEMs) traditionally relies on subjective and qualitative assessment of vendor capabilities and historical tracking of performance. Claimed technical capabilities often do not measure up to actual product fabrication. And even more frequently, low actual production yields result in late and/or short quantity delivery as well as unacceptable price increases. By combining quantitative capability measurement with statistical prediction of yields customers can more accurately determine the real capabilities and cost performance of their PWB suppliers as well as allocate actual board designs to those vendors most capable of producing specific designs cost effectively. PWB fabricators can use these same tools to more precisely price their products, prioritize capital and R&D investments, and focus ongoing process improvement activities. This paper presents quantitative methods for determining shop capability and yield performance predictability along with case studies demonstrating the effectiveness of this approach. Several OEMs now evaluate and will soon qualify PWB suppliers using these techniques. Some Electronic Manufacturing Service (EMS) provid- ers are moving in this direction as well. The key to future competitiveness in PWB fabrication markets lies in effective management of capability and performance.