Researchers from STMicroelectronics Asia Pacific Pte Ltd. (Singapore, SG), STMicroelectronics Srl (Agrate Brianza, IT), and Nanyang Technological University (Singapore, SG) developed epoxy functionalized carbon nanotubes (CNTs) and methods of forming and using epoxy functionalized CNTs as fillers in electronic applications, e.g., semiconductor devices and device packaging. More particularly, CNT-based epoxy resin composites are employed as materials for electronic packaging applications and the inclusion of CNTs as fillers chemically linked to epoxy resin macromolecules. The resulting materials showed improved chemical-physical features in terms of mechanical, thermal and electrical properties, according to inventors Charles Baudot (Singapore, SG), Maria Viviana Volpe (Pozzuoli, IT), Jeng Chien Kong and Cher Ming Tan (Singapore, SG) in U.S. Patent Application 20090299082.
Generally, epoxy resins are known for their excellent adhesion properties; chemical, thermal and mechanical resistances; and electrical insulating properties. Thus the application fields range from adhesives to composite materials for high resistance mechanical applications. Carbon nanofibers enhance the mechanical resistance of the expoxy. In the field of semiconductors, manufacturing epoxy resins are employed as materials for the packaging of electronic devices. More particularly, electronic packaging is often an important step in the process as it deals with the circuit element's interconnections, the device cooling, the total device protection and the device's mechanical support.
The manufacturing method includes functionalizing carbon nanotubes by reacting with organolithium reactants followed by a nucleophilic substitution to form the epoxy functionalized carbon nanotubes.The method of forming functionalized carbon nanotubes (CNTs) also includes functionalizing carbon nanotubes with a Bingel reaction and transesterification of ethoxylic groups of the functionalized carbon nanotubes by reacting with glycidol molecules to form the epoxy functionalized carbon nanotubes. The epoxy functionalized carbon nanotubes can also be made by functionalizing carbon nanotubes with a Prato reaction nucleophilic substitution to form the epoxy functionalized carbon nanotubes.
MWCNTs were obtained from Shanzhen Nanotechnology Co. Ltd of China and a have a claimed purity greater than about 95%, a diameter in the range from about 10 nm to about 20 nm, a length in the range from about 5 .mu.m to about 15 .mu.m, and an amorphous carbon content of less than about 3%. Inclusion of the epoxy functionalized CNTs as fillers in composite materials for electronic applications, e.g., semiconductor devices and device packaging offers superior mechanical resistance and Young's Modulus.
The enhancement of the Young's modulus of MWCNTs-based composite resins is a function of different weight percentages. The mechanical resistance enhances linearly as the weight percentage of MWCNTs increases. Also, to obtain composites having further chemical-physical improvements, high homogeneous CNTs dispersion is desired. This condition generally represents a process issue due to CNTs low solubility and the trend to create aggregates and phase separation.
