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34 SMT007 MAGAZINE I MARCH 2018 assembly testing in 2014 [3] . Resistor M0201 passives are not yet known to be offered. PCB land design options for M0201 are shown in Figure 2 as prescribed by the compo- nent manufacturer. The smallest pad size is 125µm x 70µm, which approximately matches the metal end terminal footprint. The largest pad size nearly doubles the smallest pad size area at 145µm x 120µm. The pad design of our preference is shown in Figure 3, which is at the top limit of the suggested pad size range. The motivation for using such sizeable pad dimensions include: Over-etched Cu is expected to be problem- atic at this dimensional scale. Using the largest Cu pad design should at least help to improve PCB manufacturability. Typically, the stencil aperture size mimics pad the dimensions. The largest pad area offers to ease aperture area ratios and permits poten- tially improved print volume control. Prerequisite Solder Volume The determination of a suitable stencil aper- ture capacity requires prerequisite knowledge of the appropriate reflowed solder joint form. The IPC-A-601E standard was consulted as an appropriate reference to determine this [5] . Figure 4 illustrates the model used to establish the structure of an acceptable M0201 solder joint of minimum volume. See associated Table 1 for legend. Author judgment prevailed for dimensions not explicitly provided in the 601E standard. The determination of this smallest Figure 2: M0201 vendor pad size recommendations [4] . Table 1: Label definitions for Figure 4. Figure 3: Selected M0201 pad design for drint study. Figure 4: Minimum solder volume termination model.

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