Laser processing of adhesives and polymeric materials for microelectronics packaging applications

The microelectronics industry is moving toward smaller feature sizes. The main driving forces are to improve performance and to lower cost. From the performance point of view the small distances between chips together with the short interconnection routes have of great importance in order to achieve faster operation. The application of polymers, including electrically and/or thermally conductive and insulating polymeric adhesives, for functional insulating and protective layers of interconnect substrates is beneficial to the performance and to the cost of a circuit module as well. Laser processing of polymeric materials applied for via generation image transfer, contour cutting, etc. has proved to be an efficient tool for the fabrication of interconnects substrates. The paper describes the results of research projects that are aimed at the application of CO₂ and frequency multiplied Nd:YAG lasers for the drilling of polyester foils and glass fiber reinforced epoxy laminates with the aim of interconnect via preparation. The physics of processing using five wavelengths, i.e. 10600, 1064, 532, 355 and 266 nm, were modeled, examined and evaluated. Through contacting was carried out by screen-printing with polymer thick films, by wet chemical direct plating and by evaporation of thin metal layers, but the details of metallization are not given here. The conclusion refers to the possibilities and limitations of laser processing of polymeric materials in microelectronics packaging applications