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58 The PCB Magazine • October 2014 THE SMART GRID OPPORTUNITY continues will be done on what are essentially enlarged tracks on an inner or outer layer. This arrangement provides a great deal of flexibility in stackup configuration. Profiles/ wires are bonded to a routing track, and ther- mal dissipation planes can be located on the same layer or on a facing layer co-axial with the MiB track. Ampacity data based on actual ther- mographic observations of different layup con- figurations as shown in Figure 6 shows the suit- ability of discrete wire types for medium power applications with nominal currents of 5 to 150A (40°C temp rise). Depending on the individual requirements for temperature rise and thermal management strategies this value can easily run to over 400 Amps. The current carrying capability, heat-spread- ing characteristics, and design versatility of these MiB types are directly applicable to the challenges of functionality and cost presented by smart grid RTUs. Conclusion Smart grid RTUs are a rapidly growing oppor- tunity with the need for a combination of digi- tal communications and control of mains pow- er at consumer electronics price points. Con- ventional solutions involving discrete AWG6 wire, busbars, and electromechanical relays will not meet the cost, reliability, and performance needs of distributed intelligent systems. The solutions offered by MiB technologies provide the flexibility and integration necessary for the marriage of intelligence and power necessary to realize the potentials inherent in the smart grid concept. PCB figure 6: temperature rise vs. current for four-layer stackup. (source: häusermann gmbh) william (bill) burr is owner and principal of lPC ltd, and collabo- rates with bPa as a senior con- sultant. he may be contacted at w.burr@bpaconsulting.com.