1. Process Yield v1.ppt 1 © TRW Aeronautical Systems 2001 Lucas Aerospace Define Measure Analyse Improve Control Process Yield What it is A basic measure of the process. There are a set of 4 standard definitions: Traditional Yield: traditional yield of the process, inclusive of any rework = total out x 100%, total in First Time Yield (Y FT ) : yield exclusive of rework - gives 1st time yield of each process step Rolled Throughput yield of whole process, exclusive Yield (Y RT ): of rework gives the cumulative 1st time yield at any step in a process. Normalised Yield: “average” yield of whole process sometimes used to calculate sigma metric Tip: measure yield at every step in the process, not just at the end.

2. Process Yield v1.ppt 2 © TRW Aeronautical Systems 2001 Lucas Aerospace Process Yield How to use it 100 INPUTS How many of the inputs pass through error- free at each process step ? 95 95/10080/85 8085 85/95 PROCESS STEP 4 PROCESS STEP 1 5 DEFECTS FROM 100 PROCESS STEP 2 10 DEFECTS FROM 95 PROCESS STEP 3 5 DEFECTS FROM 85 10 DEFECTS FROM 80 70/80 70 Y FT1 = 95% Y FT3 = 94% Y FT2 = 89% Y FT4 = 88% First Time Yields: Rolled Throughput Yields: = Y RT2 85% Y FT1 x Y FT2 = Y RT3 80% Y FT1 x Y FT2 x Y FT3 = Y RT 70% Y FT1 x Y FT2 x Y FT3 x Y FT4 Y FT1 = Y RT1 95% Define Measure Analyse Improve Control

3. Process Yield v1.ppt 3 © TRW Aeronautical Systems 2001 Lucas Aerospace Process Yield References ASG aTQ training module 1.9 : Measure - Process Yield How it helps Measurement of yield through the process identifies possible opportunities for improvement (OFI’s) Brainstorm possible reasons why the yield changes through the process and over time Tip: understand the inputs of the process, do not focus just on the outputs. talk to mixed groups of people involved in the process. Define Measure Analyse Improve Control