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August 2015 • SMT Magazine 21 confidence that the results will hold true when applied to a large-scale manufacturing process. Final Thoughts HiP and NWO defects are particularly dif- ficult to troubleshoot and mitigate. As Sun Tzu points outs, if the reflow process is not well de- fined and controlled (you do not know your- self) you will succumb in every battle against HiP and NWO. Having a well-controlled reflow process but not understanding the intricacies of HiP and NWO (you know yourself but not your enemy) only ensures that you will be un- able to fully defeat HiP and NWO, and should expect to suffer mix of defeat and victory. Fully understanding the mechanism behind HiP and NWO formation (knowing your enemy and yourself) means you do not need to fear the result of assembling a hundred boards. Who knew that Sun Tzu would make a good solder - ing engineer? SMT References 1. Dudi Amir et al., "Causes, Characteriza- tion and Mitigation of Non-Wet Open Defects for Area Array Components," SMTA South East Asia Technical Conference on Electronics As- sembly Technologies, 2013. 2. Alex Chan et al., "Collaboration Between OEM and EMS to Combat Head on Pillowing Defect: Part 2 – Warpage Acceptance Proposal," SMTA International Conference on Soldering and Reliability, 2013. 3. Christopher Tibbetts and Michael Anti- nori, "Refining Stencil Design to Counter HIP Defects," IPC APEX EXPO, 2015. THE WAR ON SOLDERING DEFECTS uNDER AREA ARRAY PACkAGES continues FeAture Jason Fullerton is a customer technical support engineer at alpha, an alent plc company. argonne scientists have developed a hybrid material that exhibited superlubricity at the mac- roscale for the first time. AlCF researchers helped enable the groundbreaking simulations by over- coming a performance bottleneck that doubled the speed of the team's code. While reviewing the simulation results of a promising new lubricant material, argonne re- searcher Sanket Deshmukh stumbled upon a new phenomenon. "Sanket said, 'you have got to come over here and see this. i want to show you something really cool,'" said Subramanian Sankaranara- yanan, argonne computational nanoscientist, who led the sim- ulation work at the argonne leadership computing facility (AlCF), a DoE office of Science user facility. They were amazed by what the computer sim- ulations revealed. When the lubricant materials— graphene and diamond-like carbon (Dlc)—slid against each other, the graphene began rolling up to form hollow cylindrical "scrolls" that helped to practically eliminate friction. These so-called nanoscrolls represented a completely new mech- anism for superlubricity, a state in which friction essentially disappears. "The nanoscrolls combat friction in very much the same way that ball bearings do by creating separation between surfaces," said Deshmukh, who finished his postdoctoral appointment at Ar- gonne in January. Superlubricity is a highly desirable property. considering that nearly one-third of every fuel tank is spent overcoming fric- tion in automobiles, a material that can achieve superlubricity would greatly benefit industry and consumers alike. Such ma- terials could also help increase the lifetime of countless me- chanical components that wear down due to incessant friction. Simulations Lead to Design of Near-frictionless Material

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