Elasto-plastic analysis of popcorn failure caused by cavitition unstable growth in plastic IC packaging material

Popcorn failure in Hyperelastic-plastic electronic packages under thermal load and Moisture is studied. Using the theory of finite deformation, we obtain the analytical relation between void growth and the sum of the vapor pressure induced by moisture and thermal stress induced by heat mismatch. Numerical analyses show that the critical traction decreases with decreases of yield stress-shear modulus ratio when plastic behavior of material is considered. On the other hand the critical traction decreases with increase of the initial porosity when yield stress-shear modulus ratio is given.