Novel fast cure and reworkable underfill materials

A novel fast flow, fast cure and reworkable underfill material has been developed. This nonepoxy material satisfies all the basic requirements for underfill materials, such as high glass transition temperature, low viscosity and low thermal expansion coefficient. During laboratory testing, this underfill exhibits excellent flow behavior (about 10 seconds for a quarter inch die), and fast curability (less than 5 minutes at 150°C). A distinct feature of this underfill material is its reworkability. Rework was achieved by thermal removal of the silicon die, followed by solvent cleaning of the underfill residue. Laboratory work demonstrates that the chip removal and underfill clean-up process can be completed within 5 minutes