Testing

Testing is how a fab proves a chip actually works before it ships — and critically, it happens twice, at two very different stages, because catching a bad die early is far cheaper than catching it late.

Wafer Sort → Package → Final Test → Burn-In each stage catches a different class of failure, at a different cost 1. Wafer Sort probe each die on-wafer, bin map marks good/bad 2. Package only known-good die get packaged at all 3. Final Test ATE tester full-speed functional, parametric, RF tests 4. Burn-In stress chamber elevated temp/voltage forces early failures out The "rule of ten": cost of a defect roughly 10x's at each stage it's missed A bad die caught at wafer sort costs a probe touch. Missed until it ships in a finished product, it costs a field return.

Wafer sort happens before the wafer is even cut apart. A probe card makes temporary electrical contact with every die's bond pads while it's still part of the intact wafer, running enough of the test suite to classify each die into a pass/fail bin map. Only die that pass sort get diced and sent to packaging at all — wasting a package on a die that was already known-bad would be pure cost with no chance of recovery.

Final test runs the full qualification suite on the packaged part. Once a die is bonded into its package, it goes through comprehensive functional, DC parametric, high-speed digital, mixed-signal, and (for RF parts) multi-gigahertz characterization — checking everything wafer sort's limited probe access couldn't reach, now that the part has real pins and real packaging-induced parasitics to test against.

Burn-in exists to catch a failure mode neither test stage can see directly: infant mortality. Some defects don't fail a functional test on day one but will fail within the first weeks of use — classic "bathtub curve" early-life failures. Running parts at elevated temperature and voltage for an extended period accelerates that aging artificially, forcing weak die to fail in the test chamber instead of in a customer's product. Reliability qualification — HTOL (high-temperature operating life), TC (temperature cycling), HAST (highly accelerated stress test), and MSL (moisture sensitivity level) — extends that same logic into standardized, auditable test protocols that automotive and military customers specifically require before they'll qualify a part.

ChipFoundryServices runs all four stages in-house. Our Teradyne and Advantest test platforms cover DC parametric, functional, high-speed digital, mixed-signal, and RF testing up to 40GHz, at throughputs of 100–500 wafers/day for wafer sort and 1M–10M units/month for final test, including test program development, failure analysis, and yield analysis. We qualify to commercial, automotive (AEC-Q100), medical (ISO 13485), and military (MIL-STD-883) standards, across a −55°C to +150°C temperature range, with full HTOL/TC/HAST/MSL reliability testing available.

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