Breakthrough of laser deflash system to improve productivity

Abstract

This paper describes a new build-in-vision (BIV) and vertical laser cutting method to improve capacity of laser deflash system with maintaining 3 mils lead flash remains in miniature package such as SOD923. This equipment is developed by Leshan-Phoenix Semiconductor Co. Ltd. (LPS) and supplier. The traditional laser deflash system is equipped with pre-vision for package positioning, post-vision for lead frame positioning and laser cutting per transferred data from vision system. In order to avoid more than 3 mils tiny lead mold flash which was induced by blocking or shading laser beam couple with units that locating at far end from laser center focus point. Therefore, lead frame was subjected to “Three Indexes” using slantwise cutting concept. However, it takes longer cycle time and becomes bottleneck. The new laser deflash system is equipped with new designed build-in-vision and special telecentric laser beam focus system. Build-in-vision is consists of vision camera, lighting and special designed coupling mirror which is capable of penetrating through both vision lighting and laser beam. This design assures vision positioning inspection and laser cutting simultaneously. A special tele-centric lens was designed to change the angle of laser beam for controlling the reflection of laser beam away from focus-centre point. This is to ensure laser beam vertically in the whole laser cutting field. The new system has the capability with build-in-vision and vertical laser cutting design shows significant improvement on mechanical transfer time and laser cutting time.