Numerical - Composite failure rate for given ICs & resistors with single board system

Q.  What would be the composite failure rate of a system comprising one VLSI microprocessor with 6 SSI ICs  and 10 resistors corresponding to the data given below?

Assume a single board system
PCB 2000 FIT
SSIC 70 FIT
R  20 FIT
VLSI microprocessor 600 FIT

- Published on 25 Sep 15

a. 1250 FIT
b. 2400 FIT
c. 3220 FIT
d. 4520 FIT

ANSWER: 3220 FIT
 

    Discussion

  • Satyawati Patil   -Posted on 07 Oct 15
    Given data:

    Number of VLSI microprocessor = 1
    Number of SSI ICs = 6
    Number of resistors = 10

    Assumptions for a single board system:

    PCB 2000 FIT
    SSIC 70 FIT
    R 20 FIT
    VLSI microprocessor 600 FIT

    To determine: Composite failure rate of a system (λ)=?

    Formula: λ = SSIC FIT x No. of SSI ICs + FIT of VLSI microprocessor + R (FIT) x R +PCB FIT


    Method of Computation : The composite failure rate of a system can be obtained by considering the effects of all components in the form of addition & is given by,

    λ = SSIC FIT x No. of SSI ICs + FIT of VLSI microprocessor + R (FIT) x R +PCB FIT

    λ = 70 x 6 + 600 + 10 x 20 + 2000
    = 420 + 600 + 200 + 2000
    = 3220 FIT

    Therefore, the estimated value of composite failure rate is 3220 FIT.

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