High Density Stacked Packaging Solution for SiP Applications A Flex Based Multiple Die Chip-Scale Package Technology

摘要

The miniature chip-scale and chip-size BGA package offerings continue to furnish the solution for a majority of the newer portable electronics applications. Hand-held and wireless electronics has become the most aggressive growth area for adapting high-density package technology, in both circuit board fabrication and IC packaging. The solutions continue to evolve for compressing even the most sophisticated electronic functions into a smaller and lighter finished product. Circuit board fabrication technology has made exceptional improvement over the years, furnishing higher circuit density and, physically, more robust materials. These advances have enabled IC manufacturers to focus on reducing package size as well, as evident by the rapid growth in fine-pitch and chip-size devices. Companies are now asking for multiple-chip and/or multiple-function packaging and some IC package suppliers find a degree of efficiency in stacking one die on top of another. The traditional wire-bonded package solutions are capable of furnishing a two or even three-die stack, however, overall package height becomes excessive. The package technology described in this paper is a truly innovative, folded-flex stacked die concept. The technology adapts one and two metal layer; polyimide based flexible substrate materials for in-package interconnects, allowing two, three, four or more die to be contained within a single die BGA package outline. The patented concept has already been proven in a collaborative development effort between Tessera and two customer companies.