With Integrated Modules, Reliability Must Be Designed In Too

Jul 31, 2007 3:36 PM
By Alan Elbanhawy, Director, Advanced Power System Center, Fairchild Semiconductor International, San Jose, Calif.

The first step in design verification is to make sure that the actual design meets the specifications. However, this process must be expanded to verify that these specs are met under the most demanding conditions in the module’s intended application. Those who user new technologies are very sophisticated engineers and are likely to find ways to use the devices that never occurred to the module makers. In many cases, engineers will place the modules in extremely demanding applications and environments.

The trick here, for the module makers, is to walk this tight balancing act of having sufficient safety margins to adequately meet these unknown demands without pushing the price beyond what is acceptable to users. This brings us to the last point, the final test.

Testing philosophies and methodologies vary significantly from one semiconductor company to the next. But despite the differences, they all agree on one thing: make sure that the products come out of the factory meeting all the datasheet specifications with some safety margin.

In the case of the MCM class, several tests should be performed beyond simple datasheet compliance. For instance, testing of random samples in an actual application board to assure proper performance is mandatory.
One also must mention performance characterization using corner samples. This is done by sorting out devices that have the individual components’ parameters at one end or the other of the statistical distribution of the particular parameters. These samples are to be collected for all the major parameters and fully tested to verify that the MCM modules fully meet the specs.

Integrated modules will continue to grow in numbers and complexity, placing the responsibility of detailed subsystem design in the hands of the module maker. This trend will allow the design engineer to shift his/her attention away from the dc-dc converter and concentrate on solving the design problems of the smart devices that use these modules.

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© 2007 Penton Media, Inc.