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28 SMT Magazine • October 2014 Anyone who knows anything about soldering, knows that, while it appears straight forward enough, it actually is a highly complex and multivariate process with many potential opportunities for failure. The list of things that can and do go wrong is a long one and one which has only become longer with the advent of lead-free. " " with the soldering process both at component and board level. Suffice it to say that solder is the number one cause of both defects and fail- ure in electronic assemblies and unfortunately, the higher temperatures required for the most popular lead-free solders comprised of tin, silver and copper (the so-called SAC alloys) can both damage and degrade electronic com- ponents. (Electronics reliability experts have long known and warned that there is an inverse relationship between higher temperatures and electronic device reliability.) Thus, a good component is commit- ted to assembly and after as- sembly it is defective and thus requires removal and replace- ment. Might it have survived its expected lifetime without high-temperature assembly? Who can say? On the other hand, does it really make sense to use the assembly pro- cess as a stress test to weed out possible defective parts? Moreover, there is always the potential of seeing de- vices fail due to the explosive outgassing of moisture en- trapped in the encapsulation, a phenomenon called "pop- corning." It is left to the reader to consider how much loss is ac- ceptable in their process but the argu- ment from this side is that "acceptable losses" are actually unacceptable. Wouldn't it be better to build assemblies in a more robust and less damaging way? The long time lament of many production managers is: "Why is there never enough time to do something right but always enough time to do it over?" The simpler pro- cessing proposed in SAFE manufacturing should offer plenty of time savings to meet both the production schedule and desire for high assem- bly yield if one takes the time to do it right the first time. Another concern registered by those consid- ering for the first time assembly of electronics is the fact that some odd form-factor compo- assembLY anD the Quest FOr sOLDer aLLOY-Free eLectrOnics (saFe) continues FEATurE traditional approach to electronics assembly. In everyday assembly, electronic components are placed on and interconnected to circuit boards using a soldering process such as wave solder for most through-hole components or a reflow oven to melt solder paste, which affixes surface mount components. However, when solder is eliminated and copper is substitut- ed, electronic assemblies are cre- ated by building up circuits on what can be best described as a component board. It elimi- nates a great number of steps from manufacturing, each step offering its own potential to yield a defect. The simple graphic that compares pro- cessing steps between the two approaches, which accompa- nies this article, bears quiet witness to the potential. Such an approach is not without concern. One of the concerns that is commonly registered by those first hear- ing of this radical approach to manufacturing electronic assemblies is, "How do you rework and/or repair the as- semblies?" This is a question that is perhaps best addressed by asking a counterpoint ques- tion: "Why must you rework or repair your assembly?" The an- swer to that latter question is, of course, because rework and repair are considered to be an inescapable part of the electronic manufac- turing process. And, unfortunately, when using solder to make electronics assembly intercon- nections, that is a very true assumption. Anyone who knows anything about soldering, knows that, while it appears straight forward enough, it actually is a highly complex and multivari- ate process with many potential opportunities for failure. The list of things that can and do go wrong is a long one and one which has only be- come longer with the advent of lead-free. These were identified and enumerated in an earlier article which highlighted the many different types of faults and failures that are associated