Optode Based Flip Chip Bonding on Transparent Flexible Substrates

This contribution describes a new flip chip bonding process using an ultraviolet radiation source, called an optode. For establishing a mechanical and electrical connection between die and substrate, the contact spot is irradiated from below, curing the adhesive substance by radical polymerization. Advantages over the well-established thermode curing process include the absence of thermal influence, which makes the method applicable for thermally sensitive substrate materials. Furthermore, thermode modules can be replaced by UV emitting devices such as LEDs, allowing energy-saving and low-maintenance production facilities. Reliability and stability of the final products are discussed and compared to the thermode process.