A company has developed two types of Chip Scale Packages (CSP). One is ceramic interposer land grid array (LGA) type. The other is lead on chip (LOC). Thermal cycling
test from -40°C to 125°C with 25 cycles per day is conducted and the distribution of the
thermal fatigue failure is described by the Weibull cumulative distribution function
(CDF):
F(t) = 1-e-Umy
where F(1) is the fraction failing; t is cycles to failure; n is the characteristic life to 63%
failure; and B is Weibull slope or shape parameter. For the LGA CSP, n is 602 and B is
8.78. For the LOC CSP, n is 1073 and ß is 4:32.
W
a) Evaluate the reliability of the LGA CSP and LOC CSP at 10 and 109 cycles.
b) What are the corresponding hazard rates ?
c) Plot the hazard rates vs cycles for both packages.
d) What is the expected life (in cycles) for both packages?​