Will OSP Spec Finally Be Finished?

摘要

ORGANIC SOLDERABILITY PRESERVATIVES, or, if you prefer, organic surface protectants, or OSPs, have been with us for decades. Did you know more than 60% of the world's boards use OSPs? They are in everything from smartphones to tablets to medical devices, airbags, and engine controls. Major OEMs like Intel, Apple, Cisco, Continental, Bosch, Denso, and Hitachi Automotive are known to use them. Yet when engineers discuss their preferred finishes, OSPs tend to be on the outside looking in. A new IPC task group is trying to bring an added layer of credibility to OSPs for high-temperature soldering by developing a standard, along with a series of test methods. At a glance, OSPs have ample potential. Compared to metallic finishes, they are low-cost and offer much-sought-after surface coplanarity on the coated copper pads. They emerged in the 1980s as a replacement for hot air solder leveling, which was an omnipresent but more expensive, higher maintenance process. Because of their ability to produce thin, even coatings, OSPs seemed superior for assemblers working with advanced packages, and in some cases OSPs cut the cost of the finish up to 50% over HASL and even more versus finishes containing gold or silver. Major OEMs like Lucent adopted OSPs for a large percentage of their boards.