DS-MAY26-PG28+29_Layout 1 13/05/2026 10:25 Page 1
FEATURE
SENSORS & SENSING SYSTEMS
Surviving the extremeS: Shock and vibration i N
MEMS accelerometers are increasingly used in environments where mechanical stress is both frequent and extreme. This article by
Pablo del Corro, product applications engineer, Analog Devices, explores the critical differences between shock survivability and
vibration tolerance, and outlines the relevant test standards, failure mechanisms and design strategies that enhance sensor robustness
M
EMS-based accelerometers are increasingly deployed in harsh environments where mechanical stress
is not just expected but constant. Two critical specifications often found in accelerometer data sheets are shock survivability and vibration tolerance. While they may appear similar, they serve distinct purposes and are tested differently. Understanding these differences is essential for selecting the right sensor for your application.
Shock Survivability: WithStanding the unexpected Shock survivability refers to an accelerometer’s ability to endure non- repetitive, high magnitude acceleration events. These events typically occur during the component (IC) handling, assembly, or accidental drops. • Test Standard: IEC 60068-2-27. • Test Method: Half-sine wave pulses of defined magnitude and duration, applied
across all axes.
• Purpose: Ensures the device remains functional after rare but extreme shocks.
• Failure Mechanism: Typically results in gross failures such as beam breakage in the MEMS structure but can also include system-level issues like wire bond detachment or die cracking.
vibration tolerance: Surviving the everyday Vibration tolerance, in contrast, measures the sensor’s ability to function reliably under continuous or repetitive vibrations – a common condition in many industrial and transportation applications. • Test Standard: Usually MIL-STD-883 Method 2007 (or manufacturer-defined).
• Test Method: Continuous random vibration within a specified amplitude and frequency range.
• Purpose: Validates long-term reliability under operational vibration.
• Failure Mechanism: Often leads to stiction or particle contamination due to the wear of protective mechanisms.
Why the diStinction matterS Shock and vibration stress the sensor in fundamentally different ways. A sensor rated at thousands of g’s shock survivability may fail under hundreds of g’s continuous vibration. This distinction is crucial for ensuring both sensor survival and performance. Shock survivability refers to non-repetitive extremely high magnitude impacts that can result in system-level failure, whereas vibration tolerance refers to long-term reliability. The MEMS sensor design plays a key role
1 “g” refers to gravitational acceleration (9.81m/s²).
in defining the tolerances for both metrics, shock and vibration. For example, mechanical stoppers and anti-stiction coating materials are some of the measures used in the design to protect the MEMS structure integrity. The anti-stiction coat creates a low surface energy and/or electrical insulation, whereas the mechanical stoppers prevent the proof mass from making full contact with the fixed fingers set. Figure 1 shows a simplified representation of a MEMS accelerometer. The mechanical stoppers usually have 4µm to 5µm wide crenulations (small bumps) that reduce the contact area under high shock events, which helps avoid stiction. Consider heavy
Figure 1. (a) Representation of a MEMS accelerometer structure. (b) Zoomed-in section on one of the stoppers. The stoppers help protect the MEMS structure under high shock events
2 DESIGN SOLUTIONS MAY 2026 8
machinery, like a dozer, where accelerometers are used as tilt sensors for proper operation on uneven terrain or for terrain levelling. In this application, the accelerometers may
www.designsolutionsmag.co.uk
n
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
