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PCB Component Selection With OrCAD X Live BOM

Key Takeaways

  • Component selection has to weigh electrical characteristics, assembly suitability, and general market factors (cost, availability, lifecycle status, etc.)

  • Components that are, for one or more reasons, a poor fit for an assembly require replacements that provide identical or similar electrical qualities/functionality.

  • Live BOM combines this information into a single dashboard and checks users’ BOMs for risk assessment pre-production to optimize financial, logistical, and performance.

View of Live BOM dashboard showing an overview of panels like alternate parts and design risk.

PCB component selection is easier than ever to vet with the Live BOM dashboard.

Designing electronic circuits is an involved process, but when it comes time to enter production, design teams must weigh additional physical considerations for application suitability. Size, weight, fit, temperature ratings, and more will all affect the assembly's quality and the device's long-term reliability. It can quickly become overwhelming for designers new to PCB manufacturing without DFM experience. When considering PCB component selection for circuit design and manufacturing, OrCAD X provides simulation and market analysis that helps teams optimize the various DFM aspects for any implementation.

Common Procurement Pratfalls





Most Class 2 and below electronics will have to comply with industry standards for environmental protection; however, RoHS restrictions generally make assembly a more damaging process due to the higher temperatures necessary.

Designers will want to secure RoHS-compliant components that match the assembly environment better for defect mitigation.



Production Lifecycle

Manufacturers may sunset older lines for newer, more lucrative component lines. 

Stay up-to-date on component manufacturing status and procure as soon as possible to build the minimum inventory.


Availability and Lead Times

Even perfectly selected components may not be readily available as manufacturers keep up with demand.

Designers can source from multiple manufacturers and vendors (if applicable).

PCB Component Selection for Manufacturing 

Component selection centers around functionality – after all, what good are parts that physically fit a design if they have a completely different electrical performance than what’s necessary? Performance is multidimensional: two components may have similar circuit responses but vastly different parameters. Most component engineers specify considerations when building the bill of materials (BOM):

  • Form - The form factor of the component, i.e., its dimensions. The footprint dimensions (the area reserved on the circuit for its physical boundary and pad/pin integration) are foremost. Depending on the enclosure constraints, the distance the component extends off the board (vertically or horizontally) may also be a concern.

  • Fit - The process of bonding the component to the circuit through assembly with an electrically conductive medium. The two most common methods are surface mount technology (SMT) or through-hole packaging (TH); SMT uses copper areas retained during etching on the outer layers, while TH requires drilled and plated holes. Exceptionally large or heavy components may use extra mechanical pins (i.e., pins that do not transmit information or power) or mechanical fasteners for support – these may or may not require plating in addition to drilling.

  • Function - As described above, function is the component's overall performance. For a passive element like a resistor or capacitor, this may be the in-circuit value of its impedance contributions, while more complex semiconductor ICs can feature diverse, programmable features.

Function remains the broadest classification and the most difficult to assess, as in-circuit performance can change dramatically. Rigorous simulation can determine suitability and improve signal characteristics to ensure a match between component functionality and application. PSpice gives OrCAD X Capture users a comprehensive circuit simulation and modeling tool that supports various AC and DC analysis techniques. Monte Carlo simulations allow designers to assuage the effects of component tolerances on the manufacturing yield; with this analysis, designers can adjust procurement between component price, availability, and expected yield to balance sourcing cost and resiliency. 

Probability density histogram of PSpice Monte Carlo analysis

PSpice Monte Carlo simulation is an integral tool to evaluate manufacturing yield against high-tolerance component cost.

Another advantage of the form, fit, and function schema is the ease of component replacement. This methodology distinguishes components that provide identical functionality with minimal (ideally zero in the case of drop-in replacements) changes to the component footprint and layout. Equivalent replacement components are the best substitute, failing drop-in replacements. While the concept of replacement components has historically been more of a concern for the manufacturer than the designer, an increasing prevalence of supply chain issues is forcing earlier evaluations of BOM fitness to prevent disruptions later in the DFM process. This development puts PCB designers in a quandary: how can they balance an evolving BOM against a greater demand for definiteness at an earlier stage of product design?

How Live BOM Simplifies PCB Component Selection

OrCAD X Capture has an integrated solution known as Live BOM that provides supply chain insights. Through the Live BOM dashboard, users can see an at-a-glance risk evaluation of their components from a multitude of angles, including:

  • Obsolete/End of Life (EOL) - Stay ahead of manufacturers’ end-production dates and stock inventory for production lifecycle management.
  • RoHS compliance - Find parts that meet RoHS environmental guidelines and can withstand the thermal profile of lead-free solder assemblies.
  • MPN checks - Ensure the traceability of components to the manufacturer.

Users can access up-to-the-minute supply chain data on over 1.6 billion parts using real-time tracking and forecasting powered by Sourcengine. Based on numerous factors, such as availability and compliance, Live BOM provides an A-through-D letter-grade ranking, with A being the lowest risk level. Users can navigate through the different categories of component notifications in Live BOM by toggling tile filters. 

PCB component selection is easier than ever to vet with the Live BOM dashboard.

PCB component selection is easier than ever to vet with the Live BOM dashboard.

Live BOM also features alternate part suggestions for all components with linked MPNs in the BOM. At a glance, users can see the lifecycle status of these alternate parts before substituting them into the design, but that’s not all: supply chain information displays rolling lead time, cost, and availability trends over recent months. With Live BOM, all the tools necessary to gauge a design’s component list are instantly viewable from a dashboard that integrates seamlessly into OrCAD X Capture’s overall circuit project management capabilities.       

Cadence Solutions for Supply Chain Unpredictability

PCB component selection is critical not only to the function of the design but also to more tangible factors like cost, weight, and general supply chain resilience. Designers looking to optimize their component selection can use the OrCAD X Live BOM feature for a thorough risk evaluation with up-to-the-moment information on billions of unique parts. Users can fold support from Cadence’s PCB Design and Analysis Software to comprehensively evaluate BOM performance at the individual component and circuit level. See how Live BOM can revolutionize your design and procurement workflow with the OrCAD X platform.

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