1. Purpose of the gate
Ramp complete marks the change from launching a product to running it. During the ramp, attention goes to getting volume out while keeping quality. Once yield and cycle time settle at their planned mature levels and customer quality incidents are under control, the questions become cost, competitiveness and continuous improvement. This gate decides that the change has really happened.
For power devices, mature yield depends heavily on material. Silicon carbide yield is often limited by substrate and epitaxy defects that kill large die, and gallium nitride yield by epitaxy uniformity and wafer bow. A ramp can look complete on one material source and slip on the next. The review therefore looks at yield by material lot and supplier, not just the average, and at whether the defect Pareto is stable.
The gate criteria are that yield is tracked against plan, that customer quality incidents are tracked, and that cost and yield reporting is in place. No key decision is frozen here, but the cost and yield reports and the initial cost-down plan produced at this gate are the inputs to the cost-down and lifecycle decisions that follow.
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