Evaluation of Influence of Flux Residues After Rework and Repair Process of Underfilled BGA Packages

This paper is focused on evaluation of influence of flux residues encapsulated under underfill of BGA package on failure, area size and circularity of solder balls interconnection after rework and repair process. The main goal of the work was to find out whether there will be a larger number of failures for washed or unwashed underfilled BGA packages after second reflow soldering process. Repeated cycle of reflow soldering simulated rework and repair process heat stress for neighboring devices with underfill. Results of this investigation were number of failures and failure modes of solder joints of BGA package.