Stop testing from destroying low-voltage ICs on pc boards
By Dan Strassberg -- EDN, August 21, 2003
You might have expected that voltages that don't faze older generations of ICs—say, those that operate from 5V supplies—can kill newer semiconductors—for example, devices that op-erate from 1.5V. If your production-test people are testing newer pc boards that contain low-voltage devices by performing powered-up ICT (in-circuit testing) with test systems from the bygone 5V era, now is unquestionably the time to end that practice. If you haven't observed a significant rise in failures, your customers may soon do so, because the higher voltages don't always immediately kill low-voltage devices; instead, the overvoltage sometimes causes damage that produces failures later on.
Teradyne says that it's the first supplier of ICT systems to address the problem head-on with a new technological approach. The company calls the technology SafeTest; it's available immediately in the company's TestStation ICT family, for which system prices begin at $140,000. SafeTest provides automatic driver verification, which ensures that each pin achieves its programmed threshold; back-drive-current sensing, which identifies unreliable and potentially harmful tests; a closed-loop driver, which delivers accurate programmed volt-ages even under back-driving and fault conditions.
The family also provides multilevel digital-isolation software, preventing dangerous volt-age spikes; per-pin programmable-logic thresholds and timing to eliminate overvoltage conditions and test compromises due to tester limitations; and programmable back-drive current and duration thresholds, allowing programmers to control back-drive current and duration. The product also includes a specialized digital controller that quickly executes test vectors to mini-mize back-drive duration.
Teradyne Inc, 1-978-370-2700, www.teradyne.com/prods/cbt/pressroom/pressroom.html.
