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IPC-2221 5.2.7 Vibration Design

IPC-2221 5.2.7 Vibration Design

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IPC-2221 5.2.7 Vibration Design

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  1. IPC-2221 5.2.7 Vibration Design The design of printed boards that will be subjected to vibration while in service requires that special consideration be given to the board prior to board layout. The effect on the board assembly caused by the vibration can seriously reduce the reliability of the assembly. The interrelationship between the unit, printed board assemblies, their mounting and the environmental conditions make necessary the need for a vibration analysis of the complete system very early in the design. The effect from vibration on any item within a unit can make the vibration analysis very complex.

  2. IPC-2221 5.2.7 Vibration Design Vibration analysis should be done on each piece of electronic hardware which contains printed board assemblies. The complexity of the analysis should depend on the vibration level to which the hardware will be subjected in service. The design of the printed boards will depend on the level of vibration transmitted to the board. Particular attention should be given to printed boards subjected to random vibration.

  3. IPC-2221 5.2.7 Vibration Design The following criteria should be used as guidelines for determining if the level of vibration to which the boards will be subjected is a level which would require complex vibration analysis of the board: • The random spectral density is at, or above, 0.1G2/Hz in the frequency range of 80 to 500 hertz or an unsupported board distance of greater than 76.2 mm.

  4. IPC-2221 • 5.2.7 Vibration Design • A sinusoidal vibration level at, or above, 3 Gs at a frequency of 80 to 500 Hz. • The board assembly will be subjected to Reliability Development Growth Testing (RDGT) at a spectral density at, or above, 0.07 G2/Hz for more than 100 hours in conjunction with temperature cycling.

  5. IPC-2221 • 5.2.7 Vibration Design • The following guidelines should be observed during the design of printed boards to eliminate vibration induced failures of the printed board assemblies: • The board deflection, from vibration, should be kept below 0.08 mm per mm of board length (or width) to avoid lead failure on multiple lead devices. • Positive support of all components with a weight of more than 5.0 gm per lead should be considered when the board will be subjected to vibration.

  6. IPC-2221 • 5.2.7 Vibration Design • Board stiffeners and/or metal cores should be considered to reduce the board deflection. • Cushioned mounting of relays should be considered for their usage in high level vibration environments. • Vibration isolators should be considered for mounting of units whenever practical. • The mounting height of freestanding components should be kept to a minimum. • Non-axial leaded components should be side-mounted.

  7. IPC-2221 5.2.7 Vibration Design Because of the interrelationship of the many components that makeup a system, the use of the above guidelines does not ensure the success of a unit subjected to a vibration test. A vibration test of a unit is the only way to ensure that a unit will be reliable in service.

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