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Method for an underfill fillet crack-blocking plane

IP.com Disclosure Number: IPCOM000007139D
Publication Date: 2002-Feb-27
Document File: 2 page(s) / 33K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for an underfill fillet crack-blocking plane. Benefits include improved reliability.

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Method for an underfill fillet crack-blocking plane

Disclosed is a method for an underfill fillet crack-blocking plane. Benefits include improved reliability.

Background

              Fillet cracks are seen at the die corners (see Figure 1). The fillet cracks grow into the package substrate surface and cause breaks in the Cu lines (package traces).

              Package substrate open-trace failures due to underfill fillet cracks at die corners continue to be a major failure mechanism in flip-chip packages. The failure rate for this mechanism increases as the die size increases and is considered to be a major issue for large die applications. No conventional solution exists. Underfill process optimization and the use of alternate underfill materials are options being evaluated. The problem is expected to worsen with large-die applications.

Description

      The disclosed method is a design with copper planes placed at the four die corners to stop the underfill fillet cracks from penetrating into the package substrate and breaking active metal lines.

      The copper planes are placed at the die corners where fillet cracks are seen. The size and shape of the copper planes are determined by the locus of fillet cracks seen during reliability stressing of a variety of die sizes and package geometries. A triangular blocking plane on the top layer of the package substrate at the die corner is one disclosed design (see Figure 2). Triangular blocking planes are places at the die corners to prevent fillet cracks from penet...