Five Easy Electronics Simulations That Benefit PCB Customers

May 24, 2022 Matthias Laurich

 

PCB manufacturers offering design services are becoming a common trend in the electronics industry. Investments in advanced fabrication techniques (multi-layer, HDI, RF, etc.) are important to remain competitive and attract customers. However, as PCB routing gets more complex, the likelihood of customers getting themselves into trouble goes up. By leveraging Ansys Electronics simulation tools, PCB fabricators can position themselves to provide significant value-add to their end customers. Additionally, manufacturers that offer design services can ensure they are creating the best product possible when using advanced PCB fabrication methods.

In this passage I will show five unique simulations that are: 1) Easy to set up, 2) Quick to simulate, and 3) Provide easy to interpret results. These simulations are accessible through the Ansys SIwave interface while leveraging the Ansys Electronics Enterprise license.  

Impedance Scanner

For a signal to successfully reach its destination, the impedance of the trace needs to correctly match its source. An improper trace impedance can result in undesired reflections, crosstalk, and signal attenuation. This often results in a reduced data thruput or no successful data transmission at all. Using the Impedance Scanner within Ansys SIwave, one can visualize the trace impedance across the entire routed length of the trace (Fig. 1). This visualization quickly identifies where impedance discontinuities occur, to focus improvement efforts. A compliance report is also generated outlining what signal nets are in violation of the tolerances of their respective impedance targets.

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Figure 1: Impedance Scanner Trace Impedance & Impedance Report

Resonant Modes

The optimal design of power/ground planes is critical to ensure power integrity within the design. The resonant mode simulation within SIwave calculates impedance discontinuities between planes within the PCB design. The output of the simulation (Fig. 2) shows where resonances are occurring and at what frequency. This assists in identifying where decoupling, grounding, or layout changes need to be applied. Resonant modes are also helpful in predicting radiated EMI due to power planes present on external layers.

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Figure 2: Resonant Mode Analysis

DCIR Analysis    

Understanding how power flows through a PCB is important for reliability and performance. Poor power routing creates excessive heat generation and threatens device operation and longevity. Sub-optimal routing can also emerge as EMC failures, resulting in costly board spins. The DCIR analysis within SIwave characterizes the power paths present on the PCB to prevent power integrity issues. The relevant sources and loads are assigned to the respective ICs and the DCIR analysis solves for voltage, current, and power across the PCB geometry. The DCIR shows the magnitude and direction of current (Fig. 3) as well as the current density on individual vias to get the full picture of how the power is traveling through your system.

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Figure 3: DCIR Analysis & Via Current

PCB Thermal Rise

Temperature rise on a PCB during operation is an important consideration for designs. Using the DCIR analysis results, Ansys Icepak can perform thermal simulations of the PCB to identify hot spots and areas of concern. SIwave utilizes the Icepak solver plugin to simplify the thermal analysis setup and observe the heat map within the same SIwave interface (Fig. 4). Icepak can also be used through the Electronics desktop for use in designing heat sinks, fans, and integration with larger systems.

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Figure 4: Icepak Thermal Analysis

EMI Scanner

A traditional Design Rule Check for PCB often checks for unconnected nets, shorted nets, trace/space constraints, etc. This is critical for ensuring that the PCB will not fail the “smoke test” when it is powered up for the first time after fabrication. However, just because the board does not fail to operate, doesn’t mean that EMC issues are looming in the future. By utilizing the EMI Scanner within SIwave, you can gain confidence in the PCB design by checking against user-customized design rules for EMI. SIwave quickly outputs a list of violations present on the PCB with specifics around layers, location, type of violation, and nets involved (Fig. 5). The interactive interface also highlights the location of the violation for further evaluation and mitigation.

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Figure 5: EMI Scanner Violations & Locations

As a PCB manufacturer, file compatibility is important. Ansys SIwave natively imports several of the most common PCB fabrication outputs including ODB++, IPC2581, and EDB. This ensures no matter what ECAD tool your customer uses, you are able to provide additional value through simulation insights. If you are interested in learning more about how Ansys Electronics can grow your capabilities, please reach out to your Rand Simulation Account Manager for more information.

 

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