A novel approach to die attach: Magnetic rollers with substrate thickness detection capability

IC manufacturing has become a critical operation with increasing requests for zero defective ppm, and the core front end processes such as wire bonding and die attach remain the main focus when a new material is introduced. Die attach in particular holds importance as it is the very basis of creating support for the die and subsequent connections which need to be made. However, in high volume manufacturing, there are many packages which need to be processed on a single die attach module, and conversions are necessary. These conversions are necessary for different substrate sizes and package types. Due to the design of the current die attach substrate rollers, there is much manual handling in tightening and positioning the rollers on the substrate. Some of the problems that have cropped up in the past include die attach epoxy on wire bond lead (due to poor roller tightening), substrate mask crack (excessive force from the rollers) and gradual wear and tear of the roller screws. This paper introduces a novel concept which does not require conversions between package types, and eliminates the opportunity for error. This concept will take into consideration the thickness of the substrate using magnetic substrate rollers which have sensors in them for thickness detection which will help improve the die placement accuracy. Two MAPBGA packages will be used to explain this concept and how it works thereof.