Let Z be the single-amplitude displacement at the center of the board that will give a fatigue life of about 20 million stress reversals in a random-vibration environment, based upon the 3 circuit board relative displacement. Steinberg’s empirical formula for is inches (1) where B = length of the circuit board edge parallel to the component, inches L = length of the electronic component, inches h = circuit board thickness, inches relative position factor for the component mounted on the board r = (Table 1) Constant for different types of electronic components (Table 2) C = 0.75 < C < 2.25 Equation (1) is taken from Reference 1. Table 1. Relative Position Factors for Component on Circuit Board Component Location r (Board supported on all sides) When component is at center of PCB 1 (half point X and Y). 0.707 When component is at half point X and quarter point Y. When component is at quarter point X and quarter point 0.50 Y.
Let Z be the single-amplitude displacement at the center of the board that will give a fatigue life of about 20 million stress reversals in a random-vibration environment, based upon the 3 circuit board relative displacement. Steinberg’s empirical formula for is inches (1) where B = length of the circuit board edge parallel to the component, inches L = length of the electronic component, inches h = circuit board thickness, inches r = relative position factor for the component mounted on the board (Table 1) C = Constant for different types of electronic components (Table 2) 0.75 < C < 2.25 Equation (1) is taken from Reference 1. Table 1. Relative Position Factors for Component on Circuit Board r Component Location (Board supported on all sides) 1 When component is at center of PCB (half point X and Y). 0.707 When component is at half point X and quarter point Y. 0.50 When component is at quarter point X and quarter point Y.
electronic_rd_n.docx