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PCB Trace Width – Directly Proportional To Temperature, Power, Current, Signal, And Trace Impedance

There are a plethora of tools available for PCB design. PCB designing becomes simple. A novice can easily design a simple PCB using these state-of-the-art advanced tools. As PCB design turns complex in terms of circuitry, issues crop up. PCB traces and PCB trace width gain importance. Two points connected by copper lines on a PCB are called trace lines. Specific width associates a trace line called PCB trace width. PCB trace width also has a thickness. The thickness is a layer of copper. PCB manufacturing standards determine the height of the thickness of the layer of copper. The design of PCB trace width is crucial to the performance of the circuitry. A multi-layered PCB can have many different trace widths.

PCB trace width measured in mils and thickness in oz. A typical PCB has two tracks. Signal traces and Power traces. Signal traces carry data signals. Power traces carry current in the circuit. When current flows in the power traces, excess heat generates. Hence PCB trace width for power traces needs to be kept wide enough. The copper thickness and trace width determine the cross-sectional area, resulting in current-carrying capacity determination.

As temperature rises, the PCB trace width needs to increase. Temperature rise is directly proportional to voltage drop, resistance, and maximum current. Trace length also affects temperature rise. The voltage drop needs to be kept at a minimum while designing the circuit. Power reduction occurs. Temperature increase prevented.
Greater the current greater the PCB trace width. Many tools are available to determine the PCB trace width to current carrying capacity, giving an allowance for 10 degrees temperature rise. The trace thickness is 1 oz of copper.

For circuits running at high speeds signal traces, and data lines come into play. Complex design issues occur where trace impedance and signal integrity are involved. The signal needs to maintain its original property while traveling through the trace medium. The signal phase, amplitude, waveform, power need to be at optimum levels while traveling through the trace medium. This factor needs addressing at the design stage.

Trace impedance is a factor in determining PCB trace width. Very true for high-frequency circuits. For low-frequency operation, neglect it. High-speed operation increases trace impedance. This impedance needs to be kept constant through all points. If it varies, the performance of the PCB is directly affected. The trace and its return path also have a capacitance build-up in high-speed operations. PCB design uses a controlled impedance method to keep impedance levels constant throughout the circuit.

PCB trace width is also affected by the spacing between the traces. Another factor is the trace connection to the pitch and size of the pads.

IPC221 standard used for calculating PCB trace width. Several tools are available to calculate PCB trace width. However, the design has to be perfect to input values to calculate PCB trace width. Applicable in complex high-speed circuits. Factor in the design temperature, power, current, signal, and trace impedance. The result is proper values of PCB trace width.

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