Delamination in Thermohyperelastic Plastic IC Packaging Material Due to Thermal Load and Moisture

Lamination failure as ldquopopcornrdquo form of plastic electronic packages under thermal stress induced by heat mismatch and vapor pressure induced by the moisture during the solder-reflow process is studied. When plastic electronic packages are made of thermohyperelastic materials, using the theory of cavity formation and unstable void growth in incompressible hyper-elastic material, we gained a analytical relationship between void growth and the sum of the vapor pressure and thermal stress. Numerical analyses show that plastic electronic packages will produce popcorn failure when the vapor pressure maintains saturation state during the solder-reflow process on condition that plastic electronic packages absorb a lot of moisture; popcorn failure wonpsilat occur when the moisture in voids is in single vapor phase during the solder-reflow process on condition that plastic electronic packages absorb little moisture.