Vibration Analysis of PCBs Using Laser Vibrometry
Printed circuit boards (PCBs) used in space, defense, aeronautics, and transportation cannot tolerate in-service failures.
Before deployment, these systems must pass environmental qualification tests, including vibration, shock, thermal cycling, radiation, electromagnetic compatibility (EMC), and ingress protection.
In vibration testing, PCB failures often arise from:
– Solder joint cracking
– Component detachment
– Pad delamination
– Trace fracture
All of these failures are linked to dynamic response under vibratory loading and can compromise an entire mission or system.
Understanding how PCBs actually deform and vibrate under load is essential to uncompromising reliability.
Standard tools like accelerometers provide overall board motion but cannot measure vibration at individual components, where failures originate. Populated PCBs are not uniform flat plates. They have complex mass and stiffness distributions caused by components, solder joints, and copper traces. This makes modeling and simulation highly uncertain. A Laser Doppler Vibrometer (LDV) allows non-contact vibration measurement, but conventional scanning LDVs only capture one point at a time. That means long acquisition times, repeated excitations, and risk of missing localized behaviors.Why Accelerometer-Based PCB Testing Falls Short
Using Laser Vibrometry and Laser RADAR for PCB Testing
Ommatidia’s approach uses massively parallel Laser Doppler Vibrometry (LDV), based on Laser RADAR and interferometric measurement principles, to capture dozens of measurement points simultaneously.
This method provides:
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- Non-contact measurement (no mass loading, no wiring)
- High spatial resolution across the surface of the PCB
- Synchronous data across all points without stitching or repeated sweeps
- Clear visualization of vibration behavior at the component level
It is particularly suited to environments where PCBs must survive random vibration, sine vibration, launch loads, weapons recoil, high-speed rail dynamics, or continuous fatigue.
Learn More About Laser Vibrometry →
Test Setup: PCB Under Vibration Excitation
A populated PCB was mounted on a linear shaker with vibration applied perpendicular to the plane of the board. CB under test, imaged with Ommatidia’s Q2 integrated camera. The line of dots represents the positions of the 65 simultaneous measurement points used for vibration acquisition. Key setup parameters: The frequency response revealed three distinct resonance peaks at approximately 150 Hz, 200 Hz, and 250 Hz. The shaker was then driven at each resonance frequency individually to capture the operating deflection shapes.
Vibration modes of the PCB when excited at 150Hz (left), 200Hz (center) and 250 Hz (right).
Critical Observations From High-Density Measurement
The vibration patterns differed significantly from those expected in a simple flat plate.
Components stiffened surrounding regions, altering local deflection patterns, and nodal lines were clearly visible at 150 Hz and 200 Hz.
Observation the presence of nodal lines at 150 Hz and 200 Hz.
This confirms that component placement directly affects vibration behavior.
Components positioned along high-velocity regions or near nodal lines face higher risk of solder fatigue, pad delamination, or fracture during launch, flight, transport, or impact conditions.
While this technique provides high-density operational deflection data, it is not yet a complete experimental modal analysis.
However, it enables engineers to see how real hardware behaves under load, early in the design and qualification process.
Why This Matters for Space, Defense, and Aeronautics
For teams developing spacecraft avionics, missile guidance systems, UAV electronics, railway signaling, defense radar systems, or flight control computers, this approach offers tangible benefits:
- No accelerometers required. No added mass, no wiring
- Quantitative vibration data at component level
- Detection of failure-prone areas before qualification testing
- Better correlation between simulation and hardware behavior
- Supports PCB layout optimization for harsh environments
Final Thoughts
In vibration-critical applications, understanding how a PCB deforms under excitation is essential.
Using massively parallel Laser Doppler Vibrometry based on Laser RADAR and interferometric measurement, engineers can now observe vibration velocities across components, not just board-level motion.
This high-density vibration response data can serve as the basis for a subsequent full modal analysis with resolution and speed that exceed those of traditional tools.
Future technical notes will demonstrate full modal parameter extraction workflows.
If you work in space, defence, transportation, or aeronautics and want to evaluate this method on your own hardware, Ommatidia’s team can assist with test setup and data interpretation.
Visit ommatidia-lidar.com or email sales@ommatidia-lidar.com.
