1. Purpose and scope
Once a part is approved, what the approval package describes is the baseline: the design, materials, process steps, sites, sub-tier sources, test program and control plan. Automotive customers expect to be told about changes to any of these before they are made, and usually to approve them, because a change that seems small to the supplier can change how the part behaves in a vehicle.
Semiconductor supply sees many changes over a part's life: a new fab or test site, a die shrink, a different mould compound or wire, a new tester platform, a test limit change, a second source for a substrate. Each needs to be classified: some can be made internally under change control, some need customer notification, some need customer approval and requalification, and some need a full approval resubmission. Public guidance such as the AEC guidance on process change qualification helps decide which tests a change type calls for, and the customer specific requirements decide the notification and approval route.
The stage runs whenever a change is proposed, from the first approval until the end of production. It ends for each change when the change is approved, implemented, recorded and its first lots monitored.
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