Development of Silicon Bare Die Integration by Flip-Chip within a Flexible Label
This talk will present new developments on the integration of a silicon bare die within a flexible film. The components are interconnected on electrical network by flip-chip. It was chosen to do the electrical interconnection thanks to gold stud-bumps and to perform the hybridization by thermocompression at low temperature (<150°C) in order to be compatible with polymer. Moreover, one interest of stud-bumps is that they can be made on bare dies. A glue is used to maintain the bonding between the silicon die on the film.
A silicon test vehicle was developed at CEA-LETI in order to simulate bare die. It was made on 200mm silicon wafer and designed in order to test electrical daisy chain patterns.
Two approaches will be presented: the first one is to hybridize components onto a Polyethylene-Naphthalate Film (PEN). The substrate consists of a sheet of PEN film 125mm thick. In the second approach, components are incorporated into a thin polymer layer deposited on a temporary 200mm wafer substrate of silicon or glass. After dies attach, dies are collectively thinned down to 50µm and encapsulated in a polymer. Finally, the flex is peeled from its wafer carrier. It is the first time that it was proposed to integrate silicon dies on a flexible film by Flip-Chip and to perform collective thinning at the wafer level. This study is the first step towards full electronic system in a flexible label.