A Test-Cell-Solution for 81 GHz Automotive Radar ICs

Abstract:

Improving driver safety and reducing injuries from car accidents is causing dramatic growth in ADAS (Advanced Driver Assistance Systems). Short range Radar-based ADAS operated initially at 24GHz, but the 76GHz – 81GHz market share is increasing, providing better range, bandwidth and resolution for detecting objects.  Furthermore, automotive 0 ppm failure rates require full functional test of packaged ADAS ICs at-speed.

These niche requirements have traditionally used customized test equipment, which may become obsolete as requirements change and are not well adapted for HVM.  An ideal solution is compatible with different RF and automotive applications and includes multi-temp test capability.

Previously a co-development of a 24GHz automotive radar test cell was presented. This solution is successfully deployed in HVM today.  This presentation introduces the next stage in integration and describes a test cell solution for 81GHz.

The Xcerra test cell described here integrates the LTXC MX tester, Multitest MT9510 handler, Multitest loadboard and Multitest mmWave contactor to provide a fully-calibrated HVM solution that meets the challenges of RF testing for the next-generation automotive radar devices. This solution is based on a flexible tester base that can be redeployed for other requirements, modular 24GHz and 81GHz test options and a system-level design approach to maximize OEE and minimize cost of test.

Automotive ICs operate at extended hot and cold temperatures, requiring a “tri-temp” handler to ensure the highest test coverage.  A systems-level approach to mechanical and thermal integrity enables temperature accuracy of +/-2 DegC. Maintaining temperature stability and providing a robust mechanical interface can always be challenging, but another level of difficulty is added by the signal integrity requirements of an 81GHz interface.

The difficulty of guaranteeing 81GHz signal quality requires an integrated test cell design of the complete signal path, from RF instrumentation to the DUT.  To overcome this challenge, an impedance-matched, hybrid technology mmWave contactor has been developed.  The mmWave contactor combines robust pogo pin technology with impedance-controlled cantilever technology to provide a reliable interconnect in an HVM environment. The 81GHz signals interface directly from the tester instrumentation to the contactor, eliminating any PCB transitions that would degrade performance. Calibration substrates allow in-situ calibration, eliminating time-consuming offline calibration. Finally, the mmWave contactor is fully field-replaceable, eliminating the downtime caused by factory refurbishment.

The end result is that the DUT is tested to the highest levels of coverage, enabling a guaranteed quality level for the OEMs.  This proves the value of a test cell approach to optimize overall performance, providing a cost-effective HVM solution with the highest OEE.

Version: March 2015
Presented by: Peter Cockburn, Jason Mroczkowski and John Shelley
Presented at: BiTS