Microelectronics Electrical Test
Electrical test is the proof of function against a device specification.
With the type of device that Ultra Electronics CEMS routinely manufactures, the test equipment is often much more complex than the device itself.
Using its highly skilled engineering team, CEMS has designed and developed its own bespoke automatic test equipment. The system uses a PC to control standard IEEE test equipment and drives racks of bespoke equipment generating voltages, currents and waveforms. These signals are applied to the unit under test via a device-specific interface box. The resultant output signals are read by the IEEE test equipment and the results are stored on the PC where they are compared with the specification limits, producing a pass or fail flag.
CEMS have six such ATE stations.
For a typical Chip-and-Wire build, the device is tested 3 times: First test after assembly inspection, second test after 100 hours of burn-in and final test after lid-seal and environmental screening.
In addition, temperature testing is performed at, typically, -55°C and +125°C using a thermal head which seals over the device under test and blows dry nitrogen onto the device at the temperature extremes. This is done on either a batch sample basis, or 100% depending on the customer specification.