The Research Of Evaluation On Printability Of Solder Paste

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 essential material in SMT, which is widely used in reflow soldering. Solder paste print property is critical to product yield in a SMT line. Investigation has shown that poor solder paste printability results in a large amount of defects. There are no equipments or instruments only used to testing performance of solder paste printability now. At the same time, there are some limitations in the standards and test measures of performance of solder paste printability.In this situation, the first solder paste printability tester has been invented on the base of solder paste printer used in SMT product line in this thesis. The performance of solder paste printability can be studied by the tester and the method for its use. The study includes three aspects, which are the resistance force appearing in the solder paste rolling printing, the solder ball test and solder paste wetting test. In the actual testing performance of solder paste printability, the resistance force is studied instead of the rolling rate for convenience. According to the rate, the performance of solder paste printability can be evaluated by the distance of printing process and the printing life of solder paste. Solder ball test and solder paste wetting test has been done before solder paste begin the rolling, and done again after solder paste finish rolling action. In the solder ball test, the performance of solder paste printing is 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 printability was valued on the wetting ability in the process of solder paste printing.The principle is 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.