DPU
DPU or Defects Per Unit is the average number of defects observed when sampling a population.
DPU = Total Number of Defects / Total population
Consider 100 electronic assemblies going through a functional test. If 10 of these fail the first time around, we have a first pass yield of 90%. Let's say the 10 fails get reworked and retested and 5 pass the second time around; the 5 remaining fails pass on the third attempt. Feel free to work out how this would look as a rolling yield.
DPMO
Defects per million opportunities (DPMO) is the average number of defects per unit observed during an average production run divided by the number of opportunities to make a defect on the product under study during that run normalized to one million.Defects Per Million Opportunities. Synonymous with PPM.
To convert DPU to DPMO, the calculation step is actually DPU/(opportunities/unit) * 1,000,000.
