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How to Improve an FEA Model: Proper Load Applications

In the previous two editions of ‘How to Improve an FEA Model’, we discussed how model simplification and proper mesh generation can help facilitate an improved finite element analysis (FEA).

In the third edition of the series we will discuss the importance of choosing accurate load applications as it relates to the real-world environment the object will likely encounter in its lifecycle.

Load Applications

Determining proper load applications is an extremely important step in an FEA. Load applications are the model inputs that the object is being tested for, such as a specific event like a thermal cycle, shock from a drop, vibration, or static flexure. Understanding the nuances of how to apply the loads are essential in order to simulate an event that the object will face in a real-world environment.

One common example is determining whether loads applied should be applied as static or transient. For example, if an engineer is simulating the flexure of a structure during assembly, it may be acceptable to model the load as a static displacement since strain rates are likely to be much slower and results time-independent. However, if an engineer is modeling a similar deflection caused by dropping the same assembly, they would likely need to use a transient model to capture the associated inertial effects, since the application time of the load is much faster and time-dependent effects must be captured.

In the electronics simulation world, we often deal with a similar case when simulating thermal cycling. For example, when investigating the thermal expansion and associated stresses on an entire printed circuit board assembly (PCBA) during thermal cycling, the material properties in the analysis can likely all be linear approximations, and static ramps to the minimum and maximum temperatures to investigate those stress states with no dependence on time can be reasonable. This is acceptable when board-level displacement and elastic stresses/strains are the focus of an analysis rather than creep strains/energies. However, when investigating component-level solder fatigue, solder creep properties must be included and it becomes important to accurately apply the ramp and dwell times of the thermal cycle. Creep models include time-dependent properties, so the simulated cycles must be modeled in their entirety to most accurately calculate creep strain/energy results that are used to make solder fatigue predictions.

The same real-world event is not always equal in the FEA world depending on the desired outcome of the analysis. It’s important to always keep in mind the real-world stressors the object will likely face and how those stressors could affect the component of interest. Inputting these nuances properly will result in an analysis that is accurate, valid, and actionable.

Learn more about the steps that can be taken to improve in an FEA model in the first and second edition of the “How to Improve an FEA Model” blog series.

Topic: reliability testing, finite element analysis, meshing

In the first edition of the “How to Improve an FEA Model” blog series, we discussed improving a finite element analysis (FEA) model using model simplification.

Topic: reliability testing, finite element analysis, meshing

Developing a successful and effective Finite Element Analysis (FEA) model can result in a frustrating experience for design engineers. The model needs to be simple and easy to replicate, while still complex enough to provide valid test results. This creates a problem where models are often either too simplified and approximated to provide accurate analysis, or the model is too complicated for easy processing.

Topic: reliability testing, finite element analysis, meshing

Working closely with our clients, we receive constant feedback about current challenges facing our industry. This allows us to tailor Sherlock updates to address rapidly developing landscapes as we continuously strive to improve Sherlock to make reliability predictions more accurate and more appropriate to Sherlock users’ needs.

As part of our mission to make Sherlock the most dependable and extensive reliability analysis tool available, we are rolling out an update to our flagship software. The two newest features in Sherlock addresses two key challenges: modeling non-standard BGA layouts and predicting the fatigue life of assemblies utilizing Insulated Metal Substrates (IMS).

Topic: DfR Solutions, Sherlock Automated Design Analysis, reliability testing, Reliability Physics

As the smartphone market has stagnated, semiconductor manufacturers have started to pivot their focus to automotive electronics to find the next large volume growth opportunity. This adjustment is for good reason: while smartphone volumes have not changed in over three years, automotive electronics will be the fastest growing market for integrated circuits until at least 2021.

To be successful in the competitive landscape that is automotive electronics, semiconductor manufacturers must account for differences in how automotive OEMs and their suppliers qualify integrated circuits compared to consumer products. While the differences are numerous, a key factor is the critical importance of board level reliability testing.

Topic: electronics failure, electronics test design, reliability testing, Reliability Physics, Standards Based Testing

How to Develop Board Level Reliability Test Plan

For semiconductor manufacturers entering the automotive environment, the lack of universal qualifications standards often leads to inconsistent reliability expectations. To be successful in the competitive landscape, semiconductor manufacturers must account for differences in how automotive OEMs and their suppliers qualify integrated circuits compared to consumer products. A key factor in the qualification process is the critical importance of board level reliability testing. Given the varied requirements and absence of mutually agreed standards, semiconductor manufacturers often struggle to develop a relevant and successful board level reliability test plan.

Topic: DfR Solutions, electronics failure, electronics test design, reliability testing

“After a failure” investigations are typically performed to identify root cause of failure, calculate risk exposure and develop mitigation and remediation solutions. Just like with “before a failure” investigation, there are two specific test methods that could be applied to either of the two categories – non-destructive physical analysis (NPA) and destructive physical analysis (DPA).

Topic: Failure Analysis, reliability testing, Reliability Physics

Recently I, Greg Caswell, had full knee replacement surgery on my left knee to fix a problem with osteoarthritis. I found the overall experience interesting in that the approach the doctor’s used to assess the issue, develop a plan for improving the joints capabilities and finally performing surgery as the last possibility, was similar to the Physics of Failure approach DfR Solutions uses.

Topic: Electronics Reliability, electronics failure, reliability testing

Performing a “before a failure” investigation on electronics is typically done for various reasons. One reason is to identify weak components or sub-systems before committing to a full-blown production run and its associated expenses. Comparison testing of similar component parts to reduce costs and increase reliability of existing designs, or against a competitor’s offerings is another reason. A “before a failure” investigation can validate a design to satisfy customer or market specifications, or regulatory obligations, which is common among the aerospace and medical devices fields.

Topic: Electronics Reliability, electronics failure, reliability testing