$r$	Extent along the PTH radial axes
$r_0$	Radius of hole
$r_1$	Radius of Pad
${\sigma }_r$	Radial normal stress
${\sigma }_{\theta }$	Circumferential normal stress
${\sigma }_Z$	Axial normal stress
${\sigma }_{von}$	Equivalent stress
$\Delta \epsilon$	Equivalent strain
$\mu$	Poisson’s ratio
$t$	Plating thickness
$D_j$	Flexural rigidity of plate
$\Delta T$	Temperature difference
$\alpha$	Coefficient of thermal expansion of material
$\Delta (\alpha T)$	Thermal strain, which value equals $({\alpha }_{substrate}-{\alpha }_{barrel})\cdot \Delta T$
$E_{Cu}$	Elastic modulus of barrel material
$E_E$	Elastic modulus of substrate material
$N_f$	Number of thermo-mechanical failure cycle
$q_j(r)$	Pressure function of distributed load at the jth layer of PTH
${\omega }_j(r)$	Pad deflection at the jth layer of PTH