The 12 Laws of the Wafer Fab
Twelve things the floor knows that the dashboard does not. Each one is a fourteen-second episode on fabspeak.com.
The plan says when a lot should start. The dispatcher says which lot the tool takes when it frees up. They agree less often than the plan assumes.
A held lot is waiting for a decision, not for capacity. Clearing the queue does not clear it.
A faster tool raises output only where it was the bottleneck. Everywhere else it just moves the queue.
Moves per hour say the floor is busy. Wafers out say it is producing. Only the second one ships.
A result inside the limits can still come from a process drifting toward them. Control is about the trend, not the point.
A tool on the network is not a tool in the database. The data has to be asked for, named and kept.
Every wafer skipped at metrology is a wafer whose quality is inferred. Sampling is a decision about what you accept not knowing.
A tool that appears in every excursion may simply be the tool every lot visits. Suspicion needs the denominator.
Every number on the office screen was born inside a machine and lost something on the way up. Trace it before you trust it.
A recommendation from a model is an input. The decision belongs to whoever is allowed to change the recipe.
What works on one tool, one product and one engineer's full attention has not met the night shift yet.
The ERP plans in weeks. The MES runs in minutes. The floor is whatever the MES says right now.
Distilled from the MES Fundamentals explainer series (30 episodes, Aug–Sep 2026). Principles, not statistics: nothing here is a measured number.