Assembly of flipped chip/BGA is characterized by high I/O count combined with reduced gap heights. Encapsulation material for those advanced packages will require SMT processing capabilities. Kester’s single-pass reflow encapsulant SE-Cure 9125 will be processed along with SMDs through reflow. The SPRE can be dispensed, then the die be placed into it utilizing compression flow to spread the material evenly underneath. After soldering, no secondary cure operation is required to fully polymerize the material. The encapsulant is used during reflow as a fluxer to assist wetting. After this, the underfiller is polymerized to protect the die, solder bumps and pads. Such a SPRE provides users with advantages over traditional capillary-filling material. It allows to simplify the process from two to a single step, to combine soldering and underfilling operations, saving process time, equipment expenses and costs. It also eliminates the problem of flux/underfill compatibility. By having these united in a single material, there are no negative interactions to affect the reliability of a device. To maintain consistent viscosity, flow characteristics and overall performance, storage is recommended at -40°C. Shelf life is 6 months, and pot life at room temperature is 15hrs.
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