Development Of Electronic Packages From Polypropylene/Ethylene Propylene Rubber Blends: A Double Percolation Approach

Volume resistivity of less than 10(4)Omega.cm is required for typical electrically conductive packages. Conductive polypropylene (PP) packages with the above level of conductivity value can be achieved by a use of carbon black (CB) as conductive filler. One promising method to reduce the amount of conductive fillers in composites is to use immiscible or partially miscible polymer blends. The phenomenon is known as a double percolation behavior. In this work, electrically conductive composite packages were prepared from polymer blends of PP and ethylene propylene rubber (EPR) with CB as conductive filler (PP/EPR/CB). PP/EPR mixtures at the weight ratios between 100/0 to 50/50 were blended with CB as conductive filler ranging from 0 to 30 wt% by melt mixing in an internal mixer at 200 degrees C for 10 min, followed by compression molding at the same temperature. The blends evidently provided a reduced percolation threshold with the electrical conductivity values greater than those of the CB filled PP composites. To achieve the volume resistivity of 10(4)Omega.cm, the CB content in the blend can be reduced at least 50% compared to the composite using neat PP as a matrix. Scanning electron microscopy has been used to verify the preferential location of the conductive particles and to reveal the complex morphology developed. The results presented in this study show the possibility of specially designed polymer compositions for conductive applications.