Dispensing flip chip underfill process problems and solutions

Although Flip Chip is not a new technology over the last few years we have seen this low cost interconnect solution applied to other substrates than ceramic. It is now more and more widespread that Bare Die, Flip Chip are mounted onto FR4 and even flex substrates for low cost manufacturing of advanced electronics such as PDA's, Pagers and Mobile Phones. With the use of these new substrates has arisen the need to ,,Underfill" the die after reflow. This paper derails the different hardware requirements as well as the process parameters involved and their effect on the final results obtained. Understanding each parameter and the controls that are required in a production environment is the key to correct implementation of the process.