Trimming a problem

Tin whiskers have been a problem for this industry since the introduction of lead-free solders, but techniques for eliminating them have proven elusive. As research hunt for a universal solution, they’re continually finding new techniques that reduce the chances that these vexing growths will cause problems in the field.

For example, the United Kingdom’s National Physical Laboratory has spent three years studying the mitigation effects of conformal coatings on the formation of tin whiskers. A technique using specially electroplated, interdigitated discs has been developed and a range of 20 different acrylic, polyurethane, silicone and urethane acrylate coatings have been evaluated.

All the coatings were shown to inhibit the formation of whiskers but only a limited number have provided protection over longer timescales. The results will be described next month at the IPC Tin Whiskers Conference in Fort Worth, Texas April 18-19. NPL’s Martin Wickham will also present details on a parallel project evaluating the level of whiskering on commercial components as well as a new project using a PCB assembly to evaluate conformal coating and assembly process mitigation.

That’s just one of several leading edge presentations that will be made at the Tin Whiskers Conference, which is being sponsored by a company that’s done a lot of work in tin whisker mitigation, Lockheed Martin Corp. Well-known researchers in this field, including Dave Hillman of Rockwell Collins and David Pinsky from Raytheon, will describe their latest advances.

Tin whiskers expert from Bosch Automotive Dr. Werner Huegel will describe techniques used in this high volume, high reliability market. Advances made in medical products will be described by Philips Healthcare.

Two experts from Lockheed, Linda Woody from Missile & Fire Control and Steven J. Betza, corporate director for electronics engineering and packaging, will describe their solutions. University researchers from the University of Maryland’s CALCE and the University of North Texas will discuss their research projects.

If that’s not enough, the two-day conference will be preceded by a day of workshops. Two sessions will provide nitty gritty information. With this lineup, it’s pretty much impossible not to glean several tidbits that will help even the most experienced technologists create more reliable circuit boards.

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