In our last article, we wrote about the basics of test plan development, and the value of defining test objectives, developing a justification checklist of specific test elements and identifying testing types and protocols.
The time and cost involved in executing test plans can be considerable, partially attributable to the physical nature of the tests and also to the number of experts and testing cycles required. Sherlock Automated Design Analysis™ Software minimizes the investment of these resources by simulating and simplifying a number of reliability tests:
Typically, temperature cycling presents a number of challenges including the number of required cycles, temperature variation, dwell time, ramp rates and detailed functionality spot checking during testing. Navigating the process doesn’t guarantee valid results. If the failure mode isn’t verified, the test is valueless.
Sherlock, on the other hand, forgoes this laundry list of parameters in favor of designing the board and applying the temperature cycle to it in order to clearly identify faulty components like noise, bending, corrosion, vibration and electrical loads. Knowing with certainty the number and type of failures means a quicker, and usually less costly fix that happens earlier in the process.
Plated Through Hole Fatigue
Testing hole fatigue is complicated because expansion and contraction in all planes is not uniform due to glass fiber constraint. Likewise, manually observing differing hole sizes impacts results as smaller holes fail faster and have a higher aspect ratio. The solution is usually keeping the CTE of the PCB low, but that is not realistic under normal operating conditions.
The power of Sherlock is clearly evident in addressing plated through hole fatigue. Instead of allowing for test variation through human interfaces when monitoring several key contributors to PCB functionality, Sherlock’s computerized modeling is based on the temperature map from the solder fatigue input, and uses board stack-up to calculate barrel stress for finite test results and remedy, if necessary.
Vibration and Shock
Vibration and shock testing is commonly understood to return results based on random acts, such as components shaking off due to lead failures or brittle intermetallic layer thickness. This probabilistic approach uses stress to predict probability of failure but cannot pinpoint actual failure events.
Sherlock calculates board strain during mechanical shock or vibration testing, and then uses the data to predict probability of failure. Unlike traditional probabilistic testing, the software accurately determines root causes of failure and corresponding failure events.
Conductive Anodic Filament (CAF)
Conductive Anodic Filament (CAF) tests often use an inadequate dielectric for the applied load or exceed the maximum operating temperature of the board laminate. These inaccuracies lead to myriad manufacturing issues that aren’t discovered until later in the process, when it’s more costly to detect and correct.
Sherlock gathers data on drill hole locations and diameters directly from the computerized drill files, filters by hole size and precisely identifies a “damage zone” between a pair of holes for focused analysis. This automated CAF qualification decreases the number of failures and ensures product reliability throughout manufacturing.
In addition to test simulation, Sherlock provides valuable post-test feedback:
- Failure analysis: Reviews non-destructive and destructive test methods to identify root causes of failure so true corrective action can be implemented
- Results and review compilation: Provides full documentation and a holistic review of test results to use data to its best advantage – a challenge to achieve without Sherlock
- Recommended actions: Justifies every test result or analysis with recommended, actionable next steps
Developing and executing test plans is a necessary investment because, without it, your product and brand are at considerable risk. Sherlock Automated Design Analysis™ Software keeps your test plan costs and time commitment in check, with the added benefit of achieving more accurate results and product reliability than through traditional means.
Find out more about test planning and Sherlock in our webinar, Effective Reliability Test Plan Development Using Physics of Failure. Click the button below to download the slide presentation now.