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22 The PCB Design Magazine • January 2017 So first start with the IPC-2221 recommen- dation of .4mm and then add an additional dis- tance determined by Table 6-1 of IPC-2221 as shown in Figure 5. Keep in mind that the dis- tance is expressed as a minimum. An example is shown in Figure 6. Figure 7 shows an example of a mostly finished PCB. One of the last machining op- erations is routing or scoring, often per the as- sembly contract manufacturer's specification. Notice the PCB profile is curved. Will there be enough room for tab route? In this case, it was determined that there was only enough room for tab. The mouse bite perforations were omitted due to the close proximity of traces. Will this cause another complication in the excising process? Perhaps a routing sub-operation? Snipping? Laser cut- ting? A V-score scenario geometrically showing copper pull-back requirement at worst-case least/max material conditions. Note: The addi- tional IPC-2221 electrical spacing is not includ- ed in Figure 9. Figure 5: The relevant portion of IPC-2221 (Table 6-1) of IPC-2221. Figure 6: Recommendations for minimum copper-to-edge clearance. TRUE DFM: TAKING CONTROL OF YOUR EDA TOOL