DPBO – A New Control Chart For Electronics Assembly

As six sigma (6) and better processes are demanded for higher yields and as organizations move from measuring defects in terms of parts-per-million (ppm) towards parts-per-billion (ppb), the resolution of extant control charts is becoming insufficient to monitor process quality. This work describes the development of a new statistical process control (SPC) chart that is used to monitor processes in terms of defects-per-billion-opportunities (dpbo). A logical extension of the defects-per-million-opportunities (dpmo) control chart, calculations used to derive the dpbo control limits will be presented and examples of in-control and out-of-control processes will be offered....