MTBF calculation basis

RELIABILITY CALCULATION FROM HI-REL DATA

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PART NO :xxxxx DATA SOURCE :

======================================================== The following failure rate calculation is based on the :-

ARRHENIUS EQUATION FOR ACCELERATION FACTOR (AF)

where

x

AF = e , where x = EA/k(1/TN -1/TA)

TN (OPERATING TEMP)) =55°C Normal : 50oC to 55oC

TA (ACCELERATED TJ) =150°C.............HTRB

TA (ACCELERATED TJ) =150°C..........OP LIFE

ACTIVATION ENERGY = 1eV

CONFIDENCE LEVEL = 60% (60% or 90%)Normal:60% ACCELERATION FACTOR(1) =2804.4186

ACCELERATION FACTOR(2) =2804.4186

and failure rate is calculated using chi square distribution.

FAILURE RATE = CHI(SQUARED)/(2 x TOTAL DEVICE HOURS)

2

CHI(SQUARED) = 1/2(U + SQRT{2(2R+2)-1})U =0.25

FOR 9060% CONFIDENCE Thus for xxxxx at Tj =55°C

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(1) HTRB

TOTAL HOURS AT TJ(ACC) =77000150°C)(N*H)

TOTAL HOURS AT TJ(OPERATING) =21594022955°C)

(2) OP LIFE

TOTAL HOURS AT TJ(ACC) =77000150°C)(N*H)

TOTAL HOURS AT TJ(OPERATING) =21594022955°C)

TOTAL HRS AT TJ(OPERATING) (1)+(2) =431880457

TOTAL REJECTS - PARAMETRIC (D(D) =0

TOTAL REJECTS - OPEN/SHORT(C) =1

CHI(SQUARED) - D = 1.9660% CONFIDENCE)

CHI(SQUARED) - C = 4.1960% CONFIDENCE) ..................................................................

FAILURE RATE AT 60% :

CONFIDENCE - PARAMETRIC =2(FIT)AT Tj :

DEGRADATION ===========55°C : ........................................................................:

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FAILURE RATE AT 60% : CONFIDENCE - TO INOPERATIVE = 4.9(FIT)AT Tj : (OPEN/SHORT) FAILURE ==========55°C : ........................................................................: MTBF (Inoperative failure) = 2.06E+08HRS

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MTBF (Inoperative failure) =23,518YRS

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