Refining general practices

Visual inspection, refined over the years to identify defects and faults that have been correlated to mechanical property behavior and reliability in the field, is a very important aspect of the electronic assembly process. Accordingly, a set of visual inspection criteria has been identified and generally practiced across the industry for eutectic Sn-Pb solder joints. However, the mechanical properties, visual appearance, and solder joint geometry of lead-free solders, in combination with lead-free and lead-containing terminations, are markedly different from those of PbASn, as listed in Table 28. Therefore, new visual inspection guidelines must be developed [19]. 

The objective of this chapter is to provide an overview of filtration terminology and basic engineering principles, as well as calculation methods that describe the filtration process in a generalized way. The basis equations describing the generalized process of filtration have been around for nearly 100 years, and with few refinements, continue to be applied to modem design practices. 

The pursuit of operations research consists of (a) the judgment phase (what are the problems ), (b) the research phase (how to solve these problems), and (c) the decision phase (how to act on the finding and eliminate the problems). These phases require the evaluation of objectives, analysis of an operation and the collection of evidence and resources to be committed to the study, the (mathematical) formulation of problems, the construction of theoretical models and selection of measures of effectiveness to test the models in practice, the making and testing of hypotheses as to how well a model represents the problem, prediction, refinement of the model, and the interpretation of results (usually as possible alternatives) with their respective values (payoff). The decision-maker generally combines the findings of the... 

Deciduous fruit trees are much less susceptible to oil injury in the dormant stage than when in foliage. In practice today, oils having less than about 92% unsulfonated residue are considered unsafe for general use as verdant or summer oils. Less highly refined oil has been used for dormant applications. Within recent years, however, there has... 

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