Building HAST capability at an OSAT

Background

With a new QFN line starting, the customer needed HAST capability on site rather than at an external laboratory, where turnaround was measured in weeks and queue position was unpredictable. Bias had to be applied during the test, not just temperature and humidity.

Solution

A HAST-110 system for unsaturated steam at 110 °C, 85 %RH and 0.4 MPa, plus a PCT-121 for saturated-steam testing. Custom bias fixtures carry 32 channels to the devices under test, and the chamber interlock isolates bias on any pressure or temperature excursion.

Implementation and validation

Correlation runs against the external laboratory used the same lots and conditions. Results matched on all 12 reference lots, and repeatability across three runs stayed within the JESD22-A110 acceptance band.

Outcome

Moisture-reliability results now come back in days instead of weeks, so the new line qualified on schedule. The fixtures were designed so a second package family can be added without new tooling.