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Self-Healing Underfill Material

IP.com Disclosure Number: IPCOM000021035D
Publication Date: 2003-Dec-17
Document File: 2 page(s) / 87K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that disperses a fine mix of monomer-filled capsules in the underfill matrix material. The capsules break when they come in contact with a fillet crack, and the resulting polymerization "heals" the crack.

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Self-Healing Underfill Material

Disclosed is a method that disperses a fine mix of monomer-filled capsules in the underfill matrix material. The capsules break when they come in contact with a fillet crack, and the resulting polymerization “heals” the crack.

Background

Currently, underfill is composed of an epoxy material. During the life of a package, fillet cracks often originate at the die corners and move downward into the substrate. If the cracks reach the substrate, the result can be broken Cu traces and electrical opens. In order to lower the risk of such events, a second hardened epoxy material is sometimes dispensed around the die periphery. However, this solution can only slow down the crack advance; it cannot fix the crack.

General Description

The disclosed method provides a built-in resistance to crack advance in the underfill material. Figure 1 shows the three components of a self-healing underfill material:

  • the epoxy matrix material
  • microcapsules containing a monomer (the “healing” agent)
  • a polymerization catalyst embedded in the matrix material

Figure 1 also shows an advancing crack in the material. In Figure 2, an embedded microcapsule encounters a crack, causing the microcapsule shell to break and release the monomer. In Figure 3, the monomer comes into contact with the polymerization catalyst in the matrix material, polymerization occurs, and the crack is “healed”.

Note. The microcapsules must be thick enough to withstand the stresses the underf...