Introduction: The Mechanics of Solder Alloy Wetting and Spreading

The challenge of keeping pace with emerging microelectronic device technologies has become increasingly difficult, and the fundamental limits of existing printed wiring board (PWB) technologies are becoming increasingly apparent. As a result, the domestic PWB industry now faces serious foreign competition from large, well-financed firms. The 1990 worldwide market for PWBs was $25.2 billion and has grown by just under 10% per year since 1988. North America’s demand is 28.5%, Japan’s is 27.6%, and Europe’s is 20.7%. The market is expected to grow to over $35 billion in 1993. The PWB industry in the U.S. consists of approximately 930 large companies. Of those, 600 have revenues of less than $5M/ year and 200 have revenues of between $5M and $25M/year. PWB technology is now approaching limitations that will have a profound effect on the ability to provide a means of utilizing the ever-increasing functionality that integrated circuits possess and promise. In addition, these limitations and increasing foreign competition will force many U.S. PWB companies out of business. One of the limiting processes referred to above is the age-old method of soldering.