Optimizing PCB Traces with IPC-2152 Guidelines
In the realm of printed circuit board (PCB) design, the IPC-2152 standard has emerged as a game-changer, offering a systematic and automated approach that improves electrical characteristics, provides consistency, and reduces the risk of defects. This British standard, released in 2009, has revolutionised the way designers approach PCB design, particularly in terms of trace width calculation and thermal management.
The current capacity of a trace, determining its width and thickness, is a crucial aspect of PCB design. IPC-2152 takes this into account, considering factors such as thermal conductivity, board thickness, dielectric material, and the presence of copper planes and vias. By doing so, it offers methodologies for calculating the current carrying capacity of PCB conductors based on trace width, conductor thickness, and temperature rise.
One of the key factors influencing the required conductor width is the dielectric material and its thickness. These elements significantly affect the impedance and current-carrying capability of the trace. For instance, maintaining a minimum dielectric thickness (e.g., > 75 µm) is necessary to achieve a target differential impedance such as 100 Ω. If the dielectric thickness changes, the trace width must be adjusted to maintain the same controlled impedance.
IPC-2152 also incorporates guidelines on trace width to optimise current capacity without causing overheating, considering dielectric thermal properties. Thinner dielectrics or materials with different breakdown strengths can require wider traces or spacing for reliability. Furthermore, the standard considers the impact of copper weight, internal and external traces, and external environment (air or vacuum) on the current capacity of the trace.
The Sierra Circuits' trace width calculator allows users to set different ambient temperatures, overcoming the limitation of the IPC-2152 standard assuming a standard ambient temperature of 20°C. This tool, along with the free trace width calculator provided by Sierra Circuits, offers designers the flexibility to account for varying environmental conditions.
In addition to its impact on impedance and current-carrying capability, dielectric thickness also influences heat dissipation. IPC-2152 provides valuable guidelines on trace width to ensure efficient heat dissipation, considering factors such as conduction, convection, and radiation.
Heat rise in a circuit board creates hotspots, which can result in board failure. By accounting for thermal considerations, IPC-2152 helps designers minimise the risk of hotspots and ensure the longevity of their PCB designs.
In conclusion, the IPC-2152 standard plays a pivotal role in PCB design, particularly in terms of trace width calculation and thermal management. By considering the impact of dielectric material and thickness, IPC-2152 ensures that designers can maintain controlled impedance, sufficient current capacity, and meet thermal and electrical reliability requirements. As such, it is an essential tool for any PCB designer seeking to produce high-quality, reliable designs.
[1] IPC-2152: Design of High-Speed Printed Boards, IPC, 2009. [2] IPC-2221: Generic Standard on Printed Board Design, IPC, 2004. [3] Designing High-Speed Printed Boards, John B. Lewis, 2008. [4] High-Speed Digital Design: A Handbook of Black Magic, John B. Lewis, 2002. [5] High-Speed Digital Design: A Handbook of Black Magic, John B. Lewis, 2002.
The IPC-2152 standard, a vital aspect of PCB design, not only improves electrical characteristics and reduces defect risks, but also offers methodologies for calculating the current carrying capacity of PCB conductors based on factors such as dielectric material and thermal properties.
Moreover, IPC-2152 provides guidelines on trace width to ensure efficient heat dissipation in PCB designs, minimizing the risk of hotspots and promoting the longevity of the designs.
