Authors: Russell Stapleton, Ph.D. Company: LORD Corporation Date Published: 10/13/2008
IWLPC (Wafer-Level Packaging)
Abstract: Use of large die WLCSPs, those greater than 25 mm2, is a rapid growth area in need of cost effective packaging. To address improved reliability WLCSP designers currently turn to costly assembly level adhesives, such as capillary underfills. Solder bracing is a new technology, and has been shown to deliver a cost improvement over assembly level adhesives, but it does not adhere the die to the board. Migration of cost effective solder braces to wafer level adhesives may provide the needed reliability to enable large WLCSP die designs. New chemical technologies have been developed to address the needs of wafer level adhesives, specifically latent curatives and B-staging compounds. The new curatives provide long term storage stability and cure during lead-free solder reflows. The new B-stage technology allows for rapid ambient conversion of liquid applied adhesives to tack free, low melt temperature/viscosity solids. The combination of these new chemical technologies designed specifically for wafer level adhesives should enable the next generation of low cost packaging options for flip chip devices.