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Designers commonly size traces using online calculators based on IPC-2221 or IPC-2152 charts, selecting width and thickness for a given current and allowable temperature rise (ΔT). Consideration is given to parallel conductors, although this is not a practical evaluation method for most designs. An important aspect of trace heating, especially groups of traces, is the power dissipated by the conductors. Unfortunately, the power dissipation or a method for accounting for power losses in the traces/conductors or planes is not straightforward.
The thermal design of a PCB must consider all components, their power requirements, board material, board stackup, mounting conditions, environmental conditions, and trace/conductor power losses. PCB thermal analysis considers both steady state and transient conditions. We will discuss steady-state trace heating.
It's a common practice to determine a trace size based on current, steady-state temperature rise, and trace cross-sectional area. The issue is that the IPC chart temperature rise is much higher than what would be found for most designs. Additionally, trace power is not initially assessed, leaving a significant amount of power, especially in high-current designs, to be managed later in the design cycle.
Consider a previous PCB design used to create design charts for that PCB technology. A process for creating technology-specific design charts (TSDC) can be used to develop conductor sizing design charts that account for all PCB thermal design parameters. This provides a lot of new insights into your board technology. This process for generating PCB-specific current-capacity charts is documented in U.S. Provisional Patent 63/875,465.
It’s possible to evaluate the varying current-carrying capability around different areas of the board that have more or less copper. Design charts can be made for many different environmental conditions, such as on a lab bench or for worst-case operating conditions. A previous design is not necessary; it simply minimizes iterations and provides the designer with a lot more useful information.
To continue reading this article, which originally appeared in the January 2026 I-Connect007 Magazine, click here.
