The economics for random variation are changing, particularly at advanced nodes and in complex packaging schemes.  Random variation always will exist in semiconductor manufacturing processes, but much of what is called random has a traceable root cause. The reason it is classified as random is that it is expensive to track down all of the various quirks in a complex manufacturing process or in materials or unusual use cases. In the past, most of these have not impacted yield, but the equation is beginning to change for a number of reasons

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