PROJECT TITLE :

Fabrication and Characterization of Flexible Ultrathin Chip Package Using Photosensitive Polyimide

ABSTRACT:

Assembly of thinned die has become common observe to satisfy the demand for smaller and lighter electronic merchandise. One means to achieve this goal is to embed the thinned die into 2 dielectric films, which leads to a versatile ultrathin chip package (UTCP). This paper describes a new UTCP process flow with microvia formation by commonplace UV lithography through photosensitive polyimide (PSPI). Such microvia-formation technique proved to be additional reliable than laser drilling techniques and less complicated than a dry etching method. Since the used PSPI is self-priming, a thin layer of potassium chloride was introduced as a unharness layer. In the tip, the polyimide encapsulation of the thinned die can be released from the carrier substrate and becomes a flexible chip package with a total thickness of around fifty $murm m$. Daisy-chain take a look at dies were encapsulated inside spin-coated polyimide films. Glorious chip-to-package interconnection was demonstrated by electrical daisy chain and call resistance measurements. Bending tests and thermal cycling tests were also performed on the daisy-chain check vehicles. Desired flexibility and reliability of UTCPs was observed.