Electronics exposed to shock and vibration can fail through cracked solder joints, connector movement, fractured leads, damaged components or PCB resonance. A generic “high-G” label is not enough to predict survival. Reliable design starts with the measured acceleration profile, mounting condition, temperature and required operating state during and after the event.
Shock and vibration are different loads
Shock is a transient event described by peak acceleration, duration, pulse shape and sometimes a shock response spectrum. Vibration is an oscillating input described by frequency, amplitude and duration. Random vibration uses a power spectral density profile; sine vibration can identify resonances or represent narrow-band excitation.
Two tests with the same peak acceleration can produce different stress because frequency content, duration and mounting differ. Specify the complete profile and axes rather than only a G value.
Start from the installed boundary condition
A board tested on a rigid laboratory fixture may behave differently inside an enclosure with flexible mounts, cables and connectors. Define fastener locations, torque, standoffs, board thickness, enclosure stiffness and cable support.
Heavy components and connectors can bend the PCB. Place them near supports where practical, provide mechanical retention when required and avoid concentrating mass in unsupported areas. Confirm that retention materials are compatible with temperature, cleaning, rework and service life.
Identify resonance and amplification
A structure can amplify motion near its natural frequencies. Estimate or simulate board modes, then measure resonances on representative assemblies. Frequency sweeps can reveal peaks that deserve redesign or additional damping.
Damping can reduce response, but added material changes mass, heat flow and repairability. Moving a component, changing support spacing or increasing stiffness may be more effective than adding an uncontrolled amount of adhesive.
Choose components with package mechanics in mind
Package mass, lead compliance, termination geometry and board attachment affect mechanical stress. Large ceramic capacitors can crack under board flex. Tall electrolytic capacitors, inductors, relays and transformers can load their leads. Area-array packages can place strain on solder joints when the PCB bends.
Use manufacturer vibration, shock and mounting data for the exact series. Where data is absent or the application is more severe, qualify the part on the intended board and fixture rather than assuming a similar package will behave the same.
Connectors and wiring need restraint
Vibration can cause intermittent contact, fretting wear, latch release and cable forces. Select the contact system, plating, retention and mating-cycle rating for the environment. Use strain relief and route the harness so it does not pull on the connector or board.
Verify keying and locking features under the actual direction of load. Inspect contacts and measure continuity during test when intermittent operation matters.
Workmanship affects fatigue life
Solder volume, wetting, voids, lead forming and component alignment influence stress. Define acceptance criteria and control the assembly process. Hand-applied staking or coating must have controlled material, location, cure and inspection requirements.
Board depanelization, fastening and enclosure assembly can introduce strain before the product enters service. Use strain measurement or process limits where sensitive packages are at risk.
Build a representative qualification plan
Use the governing product standard or customer requirement and tailor profiles only with documented engineering rationale. Test the correct axes, duration, temperature and operating modes. Include pre- and post-test inspection, functional checks and failure criteria.
Instrument representative locations and record fixture response so the applied test is understood. When combined environments are credible, consider sequence or combined testing; temperature can change material stiffness and solder fatigue behavior.
Sourcing documentation checklist
- Complete manufacturer part number and package.
- Shock and vibration test conditions and results.
- Temperature and qualification grade.
- PCB mounting, torque and retention instructions.
- Material, coating and workmanship requirements.
- Traceability and change-notification expectations.
- Approved alternates with engineering evidence.
For board-level considerations, see our harsh-environment PCB guide. Send the full bill of materials, drawings, test profile and documentation requirements through our contact page.
