Packaging structure and method

Abstract

A method for forming metallurgical interconnections and polymer adhesion of a flip chip to a substrate includes providing a chip having a set of bumps formed on a bump side thereof and a substrate having a set of interconnect points on a metallization thereon, providing a measured quantity of a polymer adhesive in a middle region of the chip on the bump side, aligning the chip with the substrate so that the set of bumps aligns with the set of interconnect points, pressing the chip and the substrate toward one another so that a portion of the polymer adhesive contacts the substrate and the bumps contact the interconnect points, and heating the bumps to a temperature sufficiently high to form a metallurgical connection between the bumps and the interconnect points. Also, a flip chip package is made by the method. In some embodiments the metallurgical connection includes an alloy of gold and tin at the interface between the bumps and the interconnect points.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims priority from U.S. Provisional Application No. 60 / 188,568, titled “Packaging Structure and Method”, filed Mar. 10, 2000. This application is related to commonly assigned copending U.S. Application Atty. Docket No. 60084-300301 titled “Flip Chip Interconnection Structure” and U.S. Application Atty. Docket No. 60084-300101 titled “Flip Chip-in-Leadframe Package and Method”; both said related applications are being filed on the same date as this application, and are hereby incorporated by reference in their entireties herein.BACKGROUND OF THE INVENTION [0002] This invention relates to flip chip packaging and, more particularly, to providing a Au / Sn alloy interconnection between a chip and a substrate. [0003] Conventional methods for interconnecting a flip chip to a substrate include an Anisotropic Conductive Film (ACF) with Ni or Ni / Au coated polymer particles in which a contact type interconnection is made. Fragmen...

AI Technical Summary

Benefits of technology

"The invention is a method for connecting a flip chip to a substrate using a polymer adhesive. The method involves aligning the chip with the substrate, pressing them together, and heating the chip to form a metallurgical connection between the chip's bumps and the substrate's interconnect points. The resulting connection is made through an alloy formed at the interface between the bump material and the interconnect material. The method can be used with different types of bumps and interconnect points materials, such as gold or copper plated with gold or other metals. The resulting chip package structure includes a chip with bumps and a substrate with interconnect points, with an alloy formed at the interface between the bump material and the interconnect material."

Problems solved by technology

Fragments of the polymer film which remain trapped at the interconnection point often lead to poor electrical contact and reduced reliability of the package.

Additionally, the polymer film reduces the reliability of the bonding interface during the chip bonding process.

Conventional flip chip techniques that use either ACF, Non-Conductive Adhesive (NCA) or Non Conductive Polymer (NCP) also suffer from problems in curing the adhesive on adjacent bonding sites on a substrate during the chip bonding process.

Images