Die attach interface property characterization as function of temperature using cohesive zone modeling method

Conference paper (2010)

Authors

X. Ma Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering
GQ Zhang External organisation
O van der Sluis Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering
K.M.B. Jansen Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering
W.D. van Driel Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering
L.J. Ernst Computational Design and Mechanics - Mechanical, Maritime and Materials Engineering
Research Group
Computational Design and Mechanics (Mechanical, Maritime and Materials Engineering) (TU Delft)
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Published Date

2010

Language

English

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Faculty

Mechanical, Maritime and Materials Engineering

Department

Precision and Microsystems Engineering

Research Group

Computational Design and Mechanics

Abstract

Interface delamination is one of the most important issues in the microelectronic packaging industry. Silver filled die attach is a typical adhesive used between the
die and copper die pad for its improved heat dissipation capacity. Delamination between die attach and die pad will severely impact the heat conduction and result in product
failure. In order to predict this delamination, interface properties should be characterized. Tri-material, copper-die attach-EMC, samples are made according to the package
processes. A four point bending test system is established in order to perform delamination tests at different temperatures using a universal tester Zwick/Roell Z005. In addition, a Keyence optical system is mounted to capture a series of pictures during the delamination processes. This will provide the delamination geometry information needed for
determining the interface properties. Four point bending tests have been performed at room temperature, 40, 60, 85, and 150ºC respectively. In addition pre conditioning sample are
also tested at room temperature and 85ºC respectively after 48 hours pre conditioned at 85ºC/85%RH. . Experiments show that the ¿critical delamination load¿ decreases steadily with temperature increasing. Experiments also show moisture has no effects on the ¿critical delamination load¿ compared with the dry samples tested at the same temperatures. This means that moisture has no effects on the interface toughness
between copper and die attach. To quantify the interface properties, numerical simulations of the four point bending test have been performed by using a finite element model
comprising cohesive zone elements which will describe the transient delamination process during the four point bending tests. Correspondently, the interface toughness decreases from 26.5J/m2 at room temperature to 1.9J/m2 at 150ºC as calculated from the cohesive zone element model. These results show that temperature has a large effect on the
interface toughness. By means of an extensive model parameter sensitivity study, combined with the measured delamination length in horizontal direction along the copperdie
attach interface at room temperature critical opening value has been determined.