Enhanced Polymer Passivation Layer for Wafer Level Chip Scale ...

, log
E T T T
(5-7)
y
1 2 3 4
T, bT b
bTb
3 4
1 2
(5-8)
where T has unit of degree °C; strain rate for thermal cycling was usually correspond to 10 -4 1/s.
Constants in equation (5-7) and (5-8) are given in Table 5.1.
Table 5.1 Apparent modulus and yield stress constants for SAC solders [101]
SAC solder
5.1.4 Solder-fatigue life Models
1
2
3
4
-0.0005 4.72 -0.117 37
b 1
2 b 3 b 4 b
-0.1362 67.54 5.59E-4 0.0675
Approaches for modeling of solder joint reliability can be divided into five major
categories: (a) stress-based, (b) plastic strain-based, (c) creep strain-based, (d) damage
accumulation-based, and (e) energy-based.
The stress-based model is based on the application of a stress to a component that can
result in a strain. Typically, stress-based fatigue applies to vibrational or physically shocked or
stressed components [102].
The strain-based model can be categorized into two groups: plastic strain and creep strain.
Plastic strain deformation accounts for the time-independent plastic effects while creep strain
104