# Common Types of FEA Analysis for PCB Development

April 27, 2020

Testing the strength of a PCBA

The most important tool for solving mathematical and/or scientific-based problems is the scientific method. The gist of which is that, in order to formulate a plan to solve a problem you must first define the problem; including measurable metrics. Due to the complexity or extent of many problems, incorporating this strategy many times will require that you employ a “divide and conquer” approach. In other words, it may be necessary to break the problem space into smaller sections each of which must be addressed individually to provide the overall or complete answer.

The mathematical technique that best embodies this partitioning approach is finite element analysis (FEA). FEA allows for the separation of a process or system into smaller sections for a more precise evaluation of operation, structure, etc. One of the most common uses of FEA is to track or trace material changes across and/or through a structure, enabling accurate structural analysis of stress or strain. This type of analysis is also commonly applied to PCBAs to aid in material selection prior to other structural integrity testing that may be done by your contract manufacturer (CM).

Let’s take a look at how other types of FEA analysis are utilized to aid in PCBA development, after first gaining a good understanding of the power of this technique.

## What is FEA Analysis?

A good place to start is with a general definition as below:

Finite element analysis (FEA) can be defined as a mathematical method of evaluating a process, system or structure by dividing it into smaller units and systematically determining the value(s) of defined parameters for the units. FEA allows for the distributed evaluation of the internal operation or state of a process or system.

The strength of FEA is that precision is determined by the size of the units, which can be virtually as small as desired since the technique is performed by computer simulation. However, in the case of structures, the accuracy of the technique is directly proportional to the accuracy of the model used to represent the actual structure.

Provided that a model can be quantifiably defined, FEA can be used in an almost limitless number of ways. For PCBA development, there are some implementations or types of FEA analysis that are common, as discussed in the next section.

## Types of PCB FEA Analysis

The potential uses of FEA that impact the design, manufacturing, performance and reliability of your boards are expansive. This includes impacting the components selected, how your circuits will perform and the materials chosen for your PCB stackup. You can find FEA being implemented at almost every stage of the process that results in your built boards.

Some of these utilizations are typically done by others; such as studying and documenting the performance of component voltages, currents and powers in response to incremental changes in temperature or frequency. Other types of FEA analysis that should be performed during design include the following:

### Types of FEA Analysis for PCBA Design

• Signal and Power Integrity (SI/PI) Analysis

The first requirement for all PCBAs is to function and operate as desired. The degree to

which your board meets this requirement is determined primarily by power integrity

and signal integrity. For signals, it is important to maximize parameters like SNR. It is

also important that components not only have ample power, but that noise on power

traces and grounds are minimized.

• Electromagnetic Compatibility and Integrity (EMC/EMI)

If your board has any RF devices then it is likely that EMI or noise is a concern. In most

cases, the elimination of all noise is not practical. However, it is possible to achieve the

best EM balance for the environment in which your board is deployed. For systems with

multiple PCBAs in close proximity, achieving the best balance or electromagnetic

compatibility (EMC) it is an even more important design issue.

• Thermal Analysis

Probably, the most applied type of FEA analysis is to evaluate how your board responds

to changing thermal conditions. Common analyses are heat distribution due to high

power components or environmental climate swings to help determine where to use

thermal pads, thermal vias or design a good thermal management system.

The list above is not exhaustive as FEA analysis is used by component manufacturers, CMs and testing organizations. The latter primarily for structural integrity analysis, which may prevent the need for more destructive modes of testing. Let’s see what tools are needed to incorporate the types of FEA analysis listed.

## PCB Design Tool Types of FEA Analysis

Not all PCB design packages have the functionality to perform SI/PI, EMC/EMI, and thermal FEA analysis. In fact, you will be hard-pressed to find all the capabilities, as shown below, in a single software platform.

### FEA Analysis Tools

SI/PI (PSpice)

For signal analysis of any type, including FEA analysis, PSpice is the industry standard. This tool allows you to model electronic components, circuits, ICs, and boards to evaluate signal responses w.r.t. Frequency, temperature or other parametric ranges.

PSpice: SI FEA Analysis

EMC/EMI (Clarity)

In order to analyze EM parameters accurately, a 3D perspective is needed. The 3D Solver Clarity, shown below, delivers this capability.

Clarity: EMC FEA Analysis

Thermal Analysis (Celsius)

In electronics, dealing with excess heat is one of the most significant problems that has to be solved to prevent damage and ensure safety for users. The Celsius Thermal Solver, shown below, meets this challenge by providing textual, graphical and in collaboration with Clarity, 3-D analytical results.

Celsius: Thermal FEA Analysis

The ability to perform these types of FEA analysis is available from Cadence’s PCB Design and Analysis software platform. In fact, Allegro makes it easy to integrate with other advanced tools to provide you with the capability to design and analyze components, devices, boards and systems prior to manufacturing.