Here is the abstract you requested from the IMAPS_2007 technical program page. This is the original abstract submitted by the author. Any changes to the technical content of the final manuscript published by IMAPS or the presentation that is given during the event is done by the author, not IMAPS.
|Effect of "Total System AccuracyTM" on the Underfill Process|
|Keywords: Underfill, Dispensing, Accuracy|
|Underfill process has come a long way since its conception in the late 80’s when Hitachi supplied this magic material to IBM. The primary function of the underfill was to bridge the CTE gap mismatch between silicon chips, solder bump and organic substrate. In the 80’s the chips were larger, component density was low and process challenges were somewhat simpler. Today, with the ever increasing demand on higher functionality and smaller hand held devices, electronic assemblies are subject to ever-increasing component densities. Gaps between adjacent flip chips and passive devices are growing tighter and tighter. Underfilling of these components requires extraordinary positioning capability from the dispensing equipment to ensure that the dispensed material goes exactly where it should. A brief discussion of dispensing technology along with factors effecting underfill process will be presented here for better understanding of the challenges associated with today’s underfill process. The capability required of a dispensing system to find features such as die edges, calculate positions and offsets, and drive the dispenser to the correct location with a high degree of reliability and precision is the key to reduce defects and increase yield without affecting throughput. A better understanding of a systems capability using statistical methods will lead to better process yields by reducing top die contamination and bleed-out or wet-out to adjacent components. The primary focus of this paper is to examine how the gantry capability (accuracy and repeatability) and Total System Accuracy TM, a statistical measure of the capability of a dispensing system, effect the overall underfill process. Real world examples of both needle based and jetting dispensing techniques will be used to define/examine, process capability for the dispensing system.|
|Rita Mohanty, Director Advanced Development