2/28
Reliability
Double Layer Structure
·The elongation of the length of a material defines the
strain:
d - d
x
x0
=
s
dx0
·The deformation in bending is vertical to the substrate:
z - z
z - z
n
n
(z) =
=
s
Zn
Rr
·The stress in the substrate is then:
z - zn
(z) = E (z) = E
s
s
s
s

Rr

---