Vibration Criteria Curves (BBN Criterion)

Vibration Criteria Curves (BBN Criterion)

Vibration Criteria (VC) curve (somtimes called as BBN-Criterion) was defined by firm of Bolt Beranek & Newman (Colin G. Gordon), so that the allowable vibration level for floor can be checked for sensitive equipment. See below table & typical graph for VC curve.

 

[Vibration Criteria]  

Class	Facility Equipment or Use	Vibration Criteria
		4-8 Hz RMS Acc.	8-80 Hz RMS Vel.
Class A	400x microscopes, microbalances, optical balances, proximity aligners, projection aligners	0.25 gal (1 μm, 8 Hz)	50 μm/s
Class B	lithography equipment (노광기) ( 3 um line widths )	0.13 gal (0.5 μm, 8 Hz)	25 μm/s
Class C	Up to 30000x microscopes, lithography equipment, ( 1 um line widths ) TFT-LCD stepper/scanner processes	12 μm/s
Class D	Above 30000x microscopes, lithography equipment, ( 1/2 um line widths ) TFT-LCD stepper/scanner processes	6 μm/s
Class E	Unisolated Laser and, Optical Research System, Aligner, Stepper, lithography equipment, ( 1/4 um line widths )	3 μm/s

 

 

[Vibration Criteria VC Curves]

 

 

See below sample figure to estimate the field vibration level with VC curves, which data was measured via 3 axis acceleration sensor.

 

 

[VC Curves Application]