Age or Stabilize the Device
# Age or Stabilize the Device: Compressing Years Into Hours on Purpose
Step twenty-eight's leakage-drift curve and step thirty-four's enclosure comparison both described failure mechanisms that unfold over years of field service — too slow to observe during manufacturing, and too slow to wait for before shipping a product. This step closes that gap deliberately: running the sealed device at elevated temperature and bias for a controlled conditioning period accelerates the same thermally-activated mechanisms — mobile ion drift, marginal bond degradation, any latent defect sensitive to temperature — compressing years of equivalent field exposure into hours of controlled aging. A device that would have failed slowly in a customer's hands after two years is pushed to fail now instead, while it's still cheap to discard rather than already shipped.
## 1. Elevated Temperature Accelerates the Same Mechanisms by a Predictable Factor
The acceleration factor relating burn-in time to equivalent field time depends on the activation energy $E_a$ governing whatever degradation mechanism is being screened — the same exponential, Arrhenius-type temperature dependence this process has relied on throughout, from diffusion coefficients in the thermal-budget calculations to the ion-mobility relationship behind step twenty-eight's drift concern. Running aging at a higher temperature than normal operation doesn't introduce a new failure mode; it makes an already-present, temperature-sensitive weakness progress faster, so that a short, affordable test window at elevated temperature can stand in for years of real field exposure at normal operating temperature.
## 2. Real Diagram: Screening the Infant-Mortality Population Before Shipment
## 3. The Classic Bathtub Curve: Screening Out Infant Mortality Before It Ships
Failure rate over a device population's lifetime typically follows three regimes: a declining early-failure rate dominated by latent manufacturing defects, a flat random-failure rate during normal useful life, and a rising wear-out rate much later. Aging exists specifically to push a shipped population past the first regime before it ever reaches a customer — devices with marginal bonds, residual contamination, or any other defect this process's earlier steps might have let through fail during the accelerated early-failure period, while the surviving population ships having already demonstrated it sits in the flat, stable part of the curve rather than the declining front edge of it.
## Age or Stabilize the Device's Place in the Process Lineage
Aging or stabilizing the device is step thirty-five of the 1951 grown-junction transistor's full manufacturing sequence — immediately after the transistor has been enclosed, and before final electrical tests confirm the finished specification. It is the step that deliberately accelerates every thermally-activated weakness this process's earlier steps might have left behind, compressing years of field-equivalent exposure into a controlled window so the infant-mortality population is screened out before shipment rather than discovered afterward.