Flow characterization and thermo-mechanical response for anisotropic conductive films

Dudek, R.; Schubert, Andreas; Meinel, S.; Michel, B.; Dorfmuller, L.; Kabos, Peter; Baumbach, Jan

doi:10.1109/adhes.1998.742005

Cited by 10 publications

(5 citation statements)

References 4 publications

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“…In other words, the viscoelastic behavior of the epoxy resin and the deformation of compressed Au coated micro-polymer-balls dominate the conductivity characteristics in ACF packaging process. In 1998, the flow characterization and thermomechanical response in ACF package were first investigated by Dudek et al [3]. A complex thermal and residual stress distribution was introduced during the bonding and cooling.…”

Section: Introductionmentioning

confidence: 99%

A Study on the Conductivity Variation of Au Coated Conductive Particles in ACF Packaging Process

Kuang

Hsu

Lin

2015

Journal of Nanomaterials

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In the ACF packaging process, a bonding force will be applied to the ACF structure. The finite element analysis is used to simulate the ACF packaging process. Material behavior is assumed to be superelastic for resin, viscoelastic for polymer matrix, and elastic-plastic for metal, such as bump, pad, chip, and Au-film. The axis-symmetric model is employed in FEA simulation with time-varying bonding force and operating temperature. In this study, the parameters, including conductive particle diameter, Au-film thickness, and bonding force, are analyzed with nonliner and temperature-dependent material properties. The simulation results indicate that bonding force and operating temperature have strong effects on the formation of concave on Au-film. In addition, surface wrinkle of Au-film will be induced by the bonding force. Both of the concaving and the wrinkling on Au-film will decrease the contact area between the conductive particle and the bump and the contact area between the conductive particle and the pad. Decrease of the contact area means increase of the total resistance for the ACF structure. The results show that the smaller the conductive particle diameter, the smaller the contact area. Generally, increasing the thickness of Au-film will decrease the contact areas, except at the Au-film thickness of 0.05 μm.

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Section: Introductionmentioning

confidence: 99%

A Study on the Conductivity Variation of Au Coated Conductive Particles in ACF Packaging Process

Kuang

Hsu

Lin

2015

Journal of Nanomaterials

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“…Bonding temperature and time are other critical parameters for the ACA joint reliability, since they affect the curing degree of the adhesive resin (Seppala and Ristolainen, 2004;Seppala et al, 2003) and the resulting levels of residual stresses in the assembly (Tan et al, 2004). For a given bonding temperature and bonding time, the bonding force influences the final distribution of conducting particles in the ACA assembly (Ogunjimi et al, 1995;Dudek et al, 1999). Therefore, establishing the optimum parameters for ACA bonding will contribute to achieving high quality and reliable electronics assemblies.…”

Section: Introductionmentioning

confidence: 99%

An experimental methodology for the study of co‐planarity variation effects in anisotropic conductive adhesive assemblies

Dou

Whalley

Liu

et al. 2010

Soldering & Surface Mount Tech

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Purpose-Non-planarity of assemblies and co-planarity variation effects on anisotropic conductive adhesive (ACA) assemblies have been a concern for ACA users since the materials are first devised. The primary objective of this paper is to introduce a new experimental method for studying co-planarity variation effects on ACA assemblies. Design/methodology/approach-The approach simulates non-planarity through deliberate chip rotation during the ACA bonding process, thereby locking different levels of co-planarity variation into ACA test assemblies. Scanning electron microscope (SEM) analysis and electrical joint resistance measurement using the four wire resistance (FWR) method are used to mechanically and electrically examine the connection quality of the ACA assemblies bonded with non-planar joints, for which the chip and substrate patterns are specially designed to allow joint resistance measurement using the FWR method. Findings-Typical experiments and their results are presented and analysed. The bond thickness differences between the SEM measurements and calculations indicate that the real rotations are smaller than those predicted by the calculations. The typical experimental results show that the joint resistance reduces as the deformation increases until reaching a relatively stable value after a certain deformation degree. Research limitations/implications-The average joint resistances in the rotated samples are all bigger than those measured in the un-rotated samples. This raises the question as to whether the joint resistances of ACA assemblies are more significantly affected by other affects of non-planarity than just by its effect on bond thickness. However, before this can be confirmed, more research must be done to check if this behaviour happens for different bonding forces. Originality/value-This paper reports a novel and simple experiment that can be used to examine the effects of co-planarity variation on the electrical performance of ACA assemblies, by creating different bond thicknesses that are normally difficult to achieve by changing the bonding pressure, since ACA bond thicknesses are not linearly related to the bonding force. The merit of the technique is that there is no need to manufacture chip bumps and substrate pads with different geometries, or to control the bond pressure, to achieve bond thickness variation in ACA assemblies.

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“…Industrial applications of ACAs have become increasingly common over the last two decades (Liu, 2001). They offer advantages in terms of low assembly temperature, higher component density, and reduced package size (Dudek et al, 1999). ACAs have been used in fine pitch packaging applications such as flip chip die-attach and LCD display assembly.…”

Section: Introductionmentioning

confidence: 99%

RLC effects in fine pitch anisotropic conductive film connections

Dou

Chan²,

Morris

et al. 2006

Soldering &Amp; Surface Mount Technology

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Research paper PurposeThe resistance, capacitance and inductance of Anisotropic Conductive Film (ACF) connections determine their high frequency electrical characteristics. The presence of capacitance and inductance in the ACF joint contributes to time delays and crosstalk noise as well as simultaneous switching noise (SSN) within the circuit. The purpose of this paper is to establish an experimental method for estimating the capacitance and inductance of a typical ACF connection. This can help to provide a more detailed understanding of the high frequency performance of ACF assemblies. Design/methodology/approachExperiments on the transient response of an ACF joint were performed using a digital oscilloscope capable of achieving the required ns resolution. An equivalent circuit model is proposed in order to quantify the capacitance (C) and inductance (L) of a typical ACF connection and this model is fitted to the experimental data. The equivalent model consisted of two resistors, an inductor, and a capacitor. FindingsThe capacitance and inductance of a typical ACF connection were estimated from the measured transient response using Kirchhoff's Voltage Law. The method for estimation of R, L, and C from the transient response is discussed, as are the RLC effects on the high frequency electrical characteristics of the ACF connection. Research limitations/implicationsThere was decay time deviation between the calculation and the experiment. It may be resulted from the skin effect in the high frequency response and the adhesive surrounding joint as well. The main reason may be the capacitance dielectric lost. Further research work will be done to test the dielectric lost in the ACA joint.What is original/value of paper This paper presents a new method to characterise the high frequency properties of ACA interconnections and will be of use to engineers evaluating the performance of ACF materials in high frequency applications.

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Flow characterization and thermo-mechanical response for anisotropic conductive films

Cited by 10 publications

References 4 publications

A Study on the Conductivity Variation of Au Coated Conductive Particles in ACF Packaging Process

A Study on the Conductivity Variation of Au Coated Conductive Particles in ACF Packaging Process

An experimental methodology for the study of co‐planarity variation effects in anisotropic conductive adhesive assemblies

RLC effects in fine pitch anisotropic conductive film connections

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