How Does Trace Width Calculation Impact PCB Design?

PCB Trace Width
Yes, It may Ruin Your PCB In-house Party.

Traces within the PCB are used to connect various components to various connectors. These traces can be identified as continuous paths of copper that exist on the surface of a circuit board. The trace width becomes crucial as it directly impacts on the working of the PCB. Additionally, increasing electricity flowing through PCB traces produces an immense amount of heat. Monitoring trace widths also helps minimize the heat build-up that typically occurs on boards. The conductor width also determines the resistance of the traces that directly affect the electricity flow.

Many manufacturers opt for the default trace width available, which may not be suitable for high-frequency applications. Moreover, depending on the application, the trace width varies, thus affecting the current carrying capacity of the trace. The trace width is considered as one of the most important design parameters during the PCB design. It becomes paramount to decide the adequate trace width to ensure the quality performance of the PCB. This also helps ensure the safe transportation of current without overheating and damaging the circuit board.

Sierra’s Online Tool: Impedance Calculator

We have developed an online tool for calculating the overall value of the minimum trace width. The amount of current and copper weight helps determine the minimum trace width. We offer thicker conductor traces for higher current requirements. We also offer a thicker copper weight to allow for thinner traces.

Sierra Impedance Calculator
Important Parameters

They are various factors that can affect the selection of the right trace width. Some of the key factors include the thickness of the copper layer, the type of bottom or top layer, and the length of the track. The special design guidelines are prepared for traces on PCB. These design guidelines are prepared particularly for the inner layers of the circuit board. The heat cannot easily escape through these inner layers.

Other factors such as dielectric height and dielectric constant (Dk) will also determine the trace width. We also consider other essential parameters such as the inductance and capacitance of the trace, and the propagation delay as well. This allows us to calculate the trace width precisely to a great extent as well. We also understood the need for improvements in the signal integrity of the circuit signal. This has helped us develop an Impedance Calculator for single-ended and differential pair signals. Furthermore, maintaining proper signal integrity in the PCB reduces losses such as copper losses and noise.

Key Parameters for Single-ended and Differential Pair

Having said all of this, we typically suggest our customers to opt for larger traces in order to prevent broken connection, while there is the availability of larger space on the PCB.

Impedance Calculator

Establishing Relationship Between Current Carrying Capacity of Conductors and Trace Width

The criticality of the trace width calculation also depends on parameters including the PCB copper foil cross-sectional area, the maximum current carrying capacity, and the consistent temperature rise. Additionally, parameters such as the conductive material selection and the current carrying capacity vary as per types of conductors including internal conductors and external conductors. We already defined the maximum current carrying capacity of internal conductors as half of that of external conductors.

The copper foil cross-sectional area is directly proportional to the trace width. We can also say that the temperature rise and maximum current carrying capacity are dependent on external conductors and internal conductors.

Importance of Maximum Current Carrying Capacity

The maximum current carrying capacity of the copper trace usually differs from the theoretical value due to several factors. Some of the factors include the number of components, pads, and vias. Moreover, a super large transient surge can lead to the burning down of a trace between pads during the initial supply of power or order modification that is implemented on traces.

To solve such complex issues, we prefer to increase the trace width. However, certain situations may arise that require a smaller trace width so solder mask can be applied on traces. The solder mask is typically applied to potentially burn down the PCB trace area. The solder paste can also be applied on the SMT (Surface Mount Technology) procedure. With the help of reflow soldering, the current carrying of the conductor is also increased.

In simple words, it is highly preferred to calculate the PCB trace current carrying capacity in order to decide the precise trace width. However, other external factors such as dust or contaminant pollution are also considered in real printed circuit fabrication or assembly. The excess of pollution leads to partial traces broken.

 

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