Adhesive and mechanical properties of Carbon nanotube filled thermoplastic polyimide films for microelectronics packaging

In this study the mechanical and adhesive properties of Multi-walled carbon nano- tubes (MWNTs) filled polyimide composite films (MWNT-PI) are investigated to determine their usefulness as thermo-conductive packaging materials in microelectronics. MWNTs were mixed in low wt% during synthesis at poly(amic acid) (PAA) stage. MWNT-PI films were characterized using DMTA and tensile testing to determine viscoelastic behavior and mechanical properties. Adhesive strength and adhesive energy of bonded samples were determined in accordance with ASTM D 1002 and ASTM D 3762 respectively. The fractured surfaces were examined by scanning electron microscope (SEM) to determine failure patterns. The results showed that viscoelastic behavior of MWNT-PI films changes from liquid-like to solid-like with increasing MWNT wt content. Elastic modulus and strength at break of the composite films were found to increase with increase in MWNTs wt%. However, elongation at break and breaking energy of films and lap shear strength and adhesive energy of bonded samples were found to initially increase with increase in MWNTs wt%, but then after a critical value decreases.