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www.us-tech.com
March, 2013 Highly Accelerated Stress Screenings Continued from page 50
HASS within a single system to provide faster and more effective detection of product flaws in the
marketing, and manufacturing accelerated life- testing systems. The company’s authorized test centers have conducted over 5,000 HALT and HASS tests, within 30 different countries, since 1991.
By detecting marginal problems using a
fusion of traditional burn-in, HASS and HASA, a manufacturer greatly reduces the odds of delivering a marginal product into the hands of the customer. Just as impor- tant, the rapid migration of the old toward the new stands to greatly reduce the cost of quality.
“On one product we conducted HASS on
100 percent of the units manufactured, but over time we could prove statistically that the units were not failing, so we dropped to auditing a small sample percentage,” says McLean. “Even though these were very com- plex boards with 8 to 12 layers, double-sided, fine-pitch, we still weren’t finding any defects, so we finally dropped the audits all together. After that, all we did was stuff the boards, test them, and ship the product. That’s really the ultimate money-saver and where you want to go.” Other instances of positive outcomes
Components being cycled in test chamber.
design and manufacturing phase. Catching flaws in the manufacturing phase is ideal, as these are 300 times less costly to repair than when a product is already in the marketplace, according to Frank Sun, Ph D, in his “An Introduction to Quantification of Burn-In and Environmental Stress Screening,” presented at the 2012 Annual Reliability and Main tainability Symposium. Qualmark is a recognized leader in designing,
accrued to a high-tech Fortune 100™ compa- ny that realized reductions in warranty costs of $50 million in the first year of implement- ing HASS technology. Another involved a large contract manufacturer in China that reduced its testing costs by ten-fold utilizing Qualmark’s HASS systems. Another manu- facturer calculated that HASS was 18 to 36 times more effective than burn-in.
Optimized Results Traditional burn-in chambers cannot provide
the screening effectiveness of HASS, which employs hot and cold temperature, rapid thermal ramps and repetitive shock vibration. A HASS sys- tem must be utilized to reap the benefits of accel- erated testing. By convention, a HALT/HASS system is
capable of going from –100 to +200°C, at rate of >60°C per minute as measured on the product. Unlike standard testing chambers, a HALT/HASS system must also produce vibration stresses such as pitch, roll and yaw around 3 axes (6 degrees of freedom) at the same time that hot and cold ther- mal stresses are applied. The latest Qualmark HASS systems have increased the level of energy in the lower frequency bands, which manifests the unwanted weaknesses in a product. “In one case, a product failed just one param-
eter: vibration,” McLean recalls. “We discovered it only because we stressed the product so hard that it changed the input impedance of the amplifier. At that point the software thinks that something is wrong in the front end and shuts the product down. We would have never uncovered this defect without putting it in one of Qualmark’s chambers.” Contact: Qualmark, 10390 East 48th Avenue,
Denver, CO 80238 % 888-425-8669 or 303-254-8800 fax: 303-254-8343 Web:
www.qualmark.com r
X-Ray Inspection, Double-sided PCBs
Continued from page 52
adversely affect the ability to provide a valid analy- sis. Failure to compensate for these spatial anom- alies properly may lead to false errors, incorrect readings or rejection. A 3D X-ray inspection (AXI) system must detect and compensate for board warp, waved surfaces or skewed components that may exist on the PCB. A combination of laser trian- gulation and a software-based algorithm can com- pensate for PCB sag in the recorded images. Using a true reconstruction of the solder layer
height yields a high-quality evaluation of solder joints.
Contact: GOEPEL electronic LLC, 9737 Great
Hills Trail, Ste 170, Austin TX 78759 % 512-782- 2500 fax 734-471-1444 Web:
www.goepel.com r
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