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Mold Compound Spacer and Die Attach as a Viable Alternative to Reduce Overall Die and Package Stresses in Stacked Die Packages

IP.com Disclosure Number: IPCOM000101567D
Publication Date: 2005-Mar-16
Document File: 2 page(s) / 30K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method that uses a low CTE mold compound as a die attach and spacer film in stacked die packages to reduce overall package and die stresses.

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Mold Compound Spacer and Die Attach as a Viable Alternative to Reduce Overall Die and Package Stresses in Stacked Die Packages

Disclosed is a method that uses a low CTE mold compound as a die attach and spacer film in stacked die packages to reduce overall package and die stresses.

Background

The current stacked die package assembly incorporates a high CTE and low modulus
(i.e. above a low Tg) spacer film to allow wire-bonding in between the die stack-up (see
Figure 1).  Also, the attach paste used between the second and third die typically consists of a film spacer material (i.e. a high CTE and low Tg w/ modulus, significantly decreasing the above Tg).  With this material set, the package experiences severe tensile stresses on the top die edges, which propagates edge defects into cracks during temperature cycling.

General Description

The disclosed method uses a mold compound as the spacer and/or die attach material in the stacked die package assembly. Figure 2 shows that the mold compound material is B-staged to form a film (via a pick and place) and acts as a spacer between the dies. The mold compound is also applied as an attach film between the second and third die. The existing assembly process is followed to cure the spacer and die attach films. The final encapsulating media is the same mold compound material, thereby maintaining the current assembly process flow.

By following this method, the material stack implemented in this package consists of one material throug...