Screen printing, placement and joining technologies with lead-free joining materials

This paper is focused on the results of investigations on lead-free applications in electronics manufacturing. The wide use of electronic components in the field of daily applications, the new aspects of ecology and last but not least some European Community law-making initiatives to ban environmental unfriendly materials require new materials and technologies. At the same time the manufacturing process should still guarantee high-reliability and excellent mechanical and electrical behavior of the produced components. The current point of interest is the substitution of lead in the manufacturing process. The way to solve is the use of lead-free soldering materials and/or ICAs. The development of lead-free solders and ICAs was very successful in the last years. So you can share our printing results in the 200-300 micron pitch with state-of-art products. The investigations take into consideration different surfaces on substrates and components and a representative selection of lead-free soldering materials and ICAs of different manufacturers. One criteria of the selection is the successful passing of a printing test in a 200 micron pitch structure and conventional manufacturing conditions. All test vehicles were handled under accelerate test conditions (e.g. 85°C/85 RH) and high temperature storage (150°C, 500 h) and thermal cycling (e.g. -40°C/125°C). Additional plasma treatment step was done before the manufacturing process on selected test vehicles. The effect is a higher activation of the contact surfaces of the lead-free soldering materials and improved adhesion of the ICA-joints. These special test vehicles were compared with standard boards without plasma treatment. The behavior of all investigated test vehicles are documented by their electrical, mechanical and material characteristics