The Development Of Test Instrument For Solder Paste Print Performance

The present of Surface Mount Technology-SMT brings great changes to electronic industry. SMT has many advances such as higher automatization, lower cost,less component volume,higher circle density, and better performance. All of these turn SMT to be the main stream of assembly technology. Solder paste is the most important connection material applied in SMT. The performances of solder paste have a direct influence to the quality of SMT products, especially the performance of solder paste printing. There are no equipments or instruments only used to testing performance of solder paste printing now. At the same time, there are some limitations in the standards and test measures of performance of solder paste printing. In this situation, the first instrument to test performance of solder paste printing was invented on the base of solder paste printer used in SMT product line in this thesis. The performance of solder paste printing was studied by the instrument and the items used to value performance of solder paste printing. The study included three aspects, which are the resistance force appearing in the solder paste printing, the solder ball test and solder paste wetting test. In the actual testing performance of solder paste printing, the current of motor was studied instead of the resistance force for convenience. The rate of current change, ?I/S, was proposed, according to the current change ?I and distance of printing S. According to the rate, the performance of solder paste printing was valued by the stability of printing process and the life of solder paste printing. Solder ball test and solder paste wetting test had been done in the every stage of experiments of solder paste printing. In the solder ball test, the performance of solder paste printing was valued on the base of observing solder flux residue and solder ball in the every stage of solder paste printing. In the solder paste wetting test, the performance of solder paste printing was valued on the base of observing solder flux residue on the surface of solder, bubbles presenting in the process of solder paste wetting and wetting ability in the every stage of solder paste printing. The principle was proposed that the result of current change rate was used as main reference and the result of the solder ball test and solder paste wetting test used as secondary reference. In this thesis, the performance of solder paste printing was simulated under the different printing velocity and printing pressure. The result of simulation indicated that higher printing velocity and printing pressure would improve the performance of solder paste printing if other factors were not considered.