Guarantee PCB Reliability with Vibration Simulation and Testing

Posted by Chris Montgomery on Jul 6, 2016 11:00:00 AM

iStock_81057071_LARGE.jpgThermal cycling is the source of the majority of electronics failures, yet the comparatively lower number caused by vibration fatigue can result in greater financial consequences.

It seems paradoxical, but the reality is that correcting vibration fatigue failure requires that manufacturers make fundamental design changes. The cost to do so increases in proportion to the timing and production stage in which the failure is detected. 

The solution to avoiding expensive design iterations that address vibration fatigue sounds simple: test early and often. However, repeated mechanical testing can lead to widely variable results, largely because PCB materials – particularly solder – are not designed to withstand mechanical loads.

Complementing your testing with Sherlock Automated Design Analysis™ software provides finite element simulation, analysis and modeling that doesn’t leave manufacturers to assume the physical or financial risk of vibration fatigue failure. Product reliability is virtually guaranteed.

Mechanical Vibration Testing

Mechanical vibration testing focuses on harmonic (single) and random (wide spectrum) frequencies, using two primary electronic component modes: component motion and board bending to predict Low Cycle (<100,000 cycles) or High Cycle (>100,000) vibration fatigue. The former causes rapid electronic component failure, and the latter is driven by elastic strain. The variation can produce incongruous results.

Highly Accelerated Life Testing (HALT) is the industry standard for product reliability stress testing, but it is neither meant to replicate field environments nor be a substitute for simulation due to its Grms-level vibration specification, an unusable format in simulation. Instead, HALT is designed to expose weak links in the design and provide a rapid assessment.

Between the testing approaches lies opportunity for introducing Sherlock Automated Design Analysis™ software to combine vibration fatigue predictions and simulations so reliability qualification tests provide the most value. 

Simulated Vibration Testing

It is important to reiterate that Sherlock is not intended to replace mechanical vibration testing, but rather it acts to reduce the amount of required testing – ideally to one vibration test – and guarantee reliability more quickly. 

Sherlock leverages Physics of Failure (PoF) to help you to create a full, fast and accurate finite analysis (FEA) model because the software:

  • Does not assume that the PCB is a metal plate
  • Makes it easy to put in mount points and establish critical boundary conditions
  • Lets you create laminate properties that accommodate accurate thickness analysis
  • Generates appropriate mesh size selection for FEA, ranging from 1.5-2 mm per element 

Plus, Sherlock FEA simulations allow you to capture vital information about the PCB:

  • Complex modal analysis: Find natural frequency shapes to identify accelerometer locations
  • Strain analysis and curvature-based prediction: Through board bending and deflection, find which components will fail first
  • Component motion: Model tall components to learn how they will move in a vibration situation 

Experimental measures can be used to validate Sherlock simulations and do not require running to failure to qualify responses, improving combined overall testing efficiencies and reliability outcomes.

To find out more about how Sherlock Automated Design Analysis™ software can help you guarantee PCB reliability, request your free trial now! Just click the button below.

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