1,720,988 research outputs found
Experimental analysis of mechanical and electrical characteristics of metal-coated conductive spheres for anisotropic conductive adhesives (ACAs) interconnection
Full text linkAn accurate characterization for the deformation behavior of,conductive particles is important: 1) to understand the anisotropic conductive adhesive (ACA) interconnection and 2) to optimize the ACA bonding parameter. This paper introduces an experimental technique, which has been developed to allow continuous monitoring of deformation characteristics of a single conductive particle. The load-deformation curve of a single conductive particle is measured, which provides the quantitative estimation of the mechanical and electrical characteristics of metal-coated polymer spheres used in ACAs. Based on the load-deformation result of a single conductive particle and the number of trapped particles on a bump, equivalent spring models are used to predict the deformation degree of conductive particles after flip chip assembly. For two kinds of conductive particles with different polymer cores, the mechanical and electrical characteristics of ACA interconnection were studied. Such results are used to further achieve a more sophisticated approach of the ACA bonding process and contact reliability
High current induced failure of ACAs flip chip joint
No full textThis work was supported by Center for Electronic
Packaging Materials of Korea Science and Engineering
Foundatio
Fundamental understanding of ACF conduction establishment with emphasis on the thermal and mechanical analysis
No full textThis paper presents the thermal and mechanical contribution of anisotropic conductive films (ACFs) to the electrical conduction establishment of ACF joint. The conduction mechanism of ACF joint strongly depends on the thermal and mechanical properties of ACF. Therefore, it is important to understand the relationship of thermal and mechanical properties of ACF in a bonding process with the electrical conduction establishment. In this study, ACF flip chip process was fully designed based on the material characterization and in situ process monitoring. Moreover, the effect of degree of cure oil the ACF conduction establishment was investigated in a bonding process window. The important mechanical mechanism of ACF conduction for good bonding quality is the joint clamping force due to curing and cooling-down processes of ACFs. The build-up behavior of z-axis shrinkage stress in ACF joint during curing and cooling-down processes of ACF materials was experimentally investigated with thermo-mechanical measurement of ACF, These results reveal that shrinkage stress in ACF joint developed during bonding process is the important parameter to establish the electrical conduction of interconnects using ACF material. (C) 2003 Elsevier Ltd. All rights reserved
Contraction stress build-up of anisotropic conductive films (ACFs) for flip-chip interconnection: Effect of thermal and mechanical properties of ACFs
No full textThe important mechanical mechanism for the electrical conduction of anisotropic conductive films (ACFs) is the joint clamping force after the curing and cooling processes of ACFs. In this study, the mechanism of shrinkage and contraction stress and the relationship between these mechanisms and the thermomechanical properties of ACFs were investigated in detail. Both thickness shrinkages and modulus changes of four kinds of ACFs with different thermomechanical. properties were experimentally investigated with thermomechanical and dynamic mechanical analysis. Based on the incremental approach to linear elasticity, contraction stresses of ACFs developed along the thickness direction were estimated. Contraction stresses in ACFs were found to be significantly developed by the cooling process from the glass-transition temperature to room temperature. Moreover, electrical characteristics of ACF contact during the cooling process indicate that the electrical conduction of ACF joint is robustly maintained by substantial contraction stress below T-g. The increasing rate of contraction stresses below T-g was strongly dependent on both thermal expansion coefficient (CTE) and elastic modulus (E) of ACFs. A linear relationship between the experimental increasing rate and E x CTE reveals that the build-up behavior of contraction stress is closely correlated with the ACF material properties: thermal expansion coefficient, glassy modulus, and T-g. (C) 2004 Wiley Periodicals, Inc
Experimental Analysis of Compressive Stresses in ACF Flip Chip Joint and Its Influence on ACF Joint Reliability
No full textEffect of compressive stresses in Anisotropic Conductive Films (ACFs) on contact resistance of flip chip joint
No full textConduction mechanism of Anisotropic Conductive Adhesives (ACAs): Conductor ball deformation and build-up of contraction stresses
No full textExothermic reaction induced eutectic Pb-Sn solder ball melting in the underfill curing process
Full text linkThe effects of exothermic heat generated during underfill curing on the integrity of the solder bumped package, which is an important issue for the package reliability, have been overlooked. In this study, theoretical exotherm of underfill materials during underfill curing has been calculated using a differential scanning calorimeter (DSC) at cure temperature range from 100 degreesC to 200 degreesC. The calculated exotherm was compared with the exotherm profile measured at the typical cure temperature. The effects of cure temperature, amount of underfill, and initial underfill curing temperature on the exotherm profile of underfill materials have been investigated.This work was
supported in part by the Center for Electronic Packaging Materials, Korea Science
and Engineering Foundation
Significant Reliablity Enhancement Using New Anisotropic Conductive Adhesives for Flip Chip on Organic Substrates Applications
No full textDeformation mechanism and its effect on electrical conductivity of ACF flip chip package under thermal cycling condition: An experimental study
No full textIn this study, experimental works are performed to investigate the deformation mechanism and electrical reliability of the anisotropic conductive adhesive film (ACF) joint subjected to temperature cycling for flip chip on organic board (FCOB) assemblies. This paper presents some dominant deformation parameters governing the electrical degradation in an ACF joint between a chip and a substrate when flip chip assembly is heated and cooled. The deformation mechanism of ACF flip chip assemblies during the temperature cycling are investigated using in situ high sensitivity moire interferometry. A four-point probe method is conducted to measure the real-time contact resistance of ACF joint subjected to the cyclic temperature variation. As the temperature increases below T-g of ACF, the bending displacement of assembly decreases linearly. At the temperature higher than T-g of ACF, there is no further change in bending behavior and in-plane deformations of a chip and a substrate become approximately free thermal expansion. It is because that soft-rubbery ACF at the temperature above T-g cannot provide the mechanical coupling between a chip and a substrate. The effect of bump location on the temperature dependent contact resistance is evident. A characteristic hysteresis in bending curves is observed and discussed. The contact resistance of the corner bumps increases with increasing temperature at a higher rate when compared to that of the middle. Failure analysis is performed to examine the ACF interconnections before and after thermal cycling test. The results indicate that during the thermal loading, the shear deformation is more detrimental to the electrical degradation of ACF joints than normal strain. (c) 2005 Elsevier Ltd. All rights reserved.This work was supported by Center for Electronic
Packaging Materials of Korea Science and Engineering
Foundation. The authors would like to thank Dr. S.B.
Lee at Korea Advanced Institute of Science and Technology
for his valuable advices on a moire´ analysis
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