Simulation of the aging behavior of isotropic conductive adhesives

Abstract

Although, in numerous studies the changes of contact resistance during accelerated aging under elevated temperature and humidity were observed there is still a lack of understanding of degradation mechanisms. Some models illustrate connections between the contact behavior and parameters of the conductive filler. In addition to these considerations in our paper we describe the macroscopic behavior by considering the microscopic resistance change between the conductive particles themselves and between parh'cles and contact pads. For this purpose, we calculated the electrical contact resistance with a two dimensional numeric simulation. Herein the conductive particles are modeled by randomly distributcd ellipses placed between two parallel electrodes comparable to silver flakes as known from metallographic: cross sections of our contact samples. The voltage and current distribution and the contact resistance as well are calculated by transfoming this model into a resistor network During a forced aging process different opposite effects occur in an adhesive joint. One effect is the increase of entire resistance due to a degradation of the interpam'cle contact. Another effect is the decrease of resistance caused by a post curing of the resin during aging of the adhesive joint. This behavior was experimentally determined in a previous investigation. In accordance to these effects we simulate the aging process of the joint by introducing different time dependencies of the interparticle resistance. The goal of this study is to provide a deeper understanding of the changes of the macroscopic contact behavior due to different environmental impacts.

Isotropic conductive adhesives in electronics

“…A dynamic model of compression effects demonstrates flake alignment quite dramatically (Mundlein and Nicolics, 2004), but as the structure fills up, the modeling process becomes more and more time-consuming. A potential energy technique has proved effective (McCluskey et al, 1998) in reducing computation time, and compression algorithms can be applied to initially well-separated particles (Mustoe et al, 1999;Mundlein et al, 2002;Nicolics, 2004, 2005). Su and Qu (2004) extended this compression concept by modeling the curing process itself.…”

Ising Model for Conductive Percolation in Electrically Conductive Adhesives by Considering Random Arrangement of Conducting Particles

“…The properties of composites of particles dispersed in continuum media have been reported by many authors several decades, covering numerous composites, such as conductive particles dispersed in insulating adhesives (electrically conductive adhesives) for microelectronic applications (Mikrajuddin et al, 2000;Yim et al, 2008;Lin and Chen, 2008;Li et al, 2008;Lin and Chiu, 2008;Morris and Lee, 2008;Zenner et al, 2008;Inoue et al, 2008;2009;Inoue and Suganuma, 2007;2009;Kim and Paik, 2008;Mundlein et al, 2002;Li et al, 1993;Tongxiang et al, 2008;Lee et al, 2005;Sander et al, 2002;, insulating particles dispersed in Ionic adhesive for use in solid batteries or fuel cells (Mikrajuddin et al, 2000;1999), colloidal systems (Lu et al, 2006;, pharmaceutical tablets (Stromme et al, 2003) and other composites such as fibers in concrete (Newman, 2002) and fly ash-concrete (Mohan et al, 2012). One interesting phenomenon exhibited by these composites is the occurrence of percolation threshold, a quantity which divides two strongly different states, such as conductive and insulating states (Mikrajuddin et al, 2000;1999), magnetic and nonmagnetic states (Thorpe, 1978), crystal and amorphous states, Surprisingly, in recent progress, the percolation phenomena are also applied to other fields, in the past of which likely did not show any relation with material composites such as communication systems such as the internet and other Peer-To-Peer networks (PastorSatorras and Vespignani, 2007), dynamics of epidemic spreading (Anderson and May, 1992;Meyers, 2007), HIV infection to AIDS (Kamp and Bornholdt, 2002), social networks …”