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Bevel Cut on the Die Backside to Reduce Package Die Sidewall-to- Polymer Delamination

IP.com Disclosure Number: IPCOM000100670D
Publication Date: 2005-Mar-16
Document File: 3 page(s) / 25K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that uses a die with a bevel cut (i.e. a 45o cut at all edges) to improve the adhesion of polymers to the die. Benefits include reducing delamination and corner cracks.

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Bevel Cut on the Die Backside to Reduce Package Die Sidewall-to- Polymer Delamination

Disclosed is a method that uses a die with a bevel cut (i.e. a 45o cut at all edges) to improve the adhesion of polymers to the die. Benefits include reducing delamination and corner cracks.

Background

Currently, high peeling stress at the edges and top of the die cause die sidewall delamination on exposed die flip chip packages; this delamination occurs during assembly and reliability stress testing. Often, the delamination propagates down and forms a crack in the active layer of the silicon (see Figure 1). The following are current solutions to this problem:

§         Increasing the adhesion of polymer materials by  using a coupling agent. Unfortunately, no matter how much coupling agent is used, delamination still takes place due to the high tensile stress at the die edges.

§         Roughening the die surface. This method can improve the adhesion and wetting of the polymer to die sidewall; however, it is a costly and time consuming method.

§         Using an adhesive, such as a capillary underfill, between the mold compound and die. This improves the adhesion of die to the mold compound; however, this solution is not sufficient because it permits exposed corners, which contact the mold compound. Delamination still can occur at these corners.

General Description

The disclosed method uses a die with a bevel cut to avoid die sidewall delamination, die cracking, and mold corner crack issues. The bevel cut at t...