Effect of drop impact energy on contact resistance of anisotropic conductive adhesive film joints

2004 ◽  
Vol 19 (6) ◽  
pp. 1662-1668 ◽  
Author(s):  
Rashed Adnan Islam ◽  
Y.C. Chan ◽  
B. Ralph
Keyword(s):  
Contact Resistance ◽  
Impact Energy ◽  
Drop Impact ◽  
Conductive Adhesive ◽  
Mechanical Shock ◽  
Particle Deformation ◽  
Adhesive Film ◽  
Anisotropic Conductive Adhesive ◽  
The Impact ◽  
Microscopy Images

The contact resistances investigated in this study of anisotropic conductive adhesive film joints using Au/Ni bumps and flexible substrates are found to be increased by the drop impact energy and also by the combined effect of heat/humidity and the impact energy. The samples humidified at 85 °C/85% RH for 384 h, on which impact energy of 50 J was induced, exhibit the most severe results. The contact resistance increases by 700%, which had been about 0.062 Ω in the as-bonded condition. The samples without humidification showed a sluggish and gentle increase in contact resistance with induced drop impact energy. The contact resistance was found to be increased by 400% after absorbing 90 J energy. Scanning electron microscopy images show particle deformation due to abrasion and friction between the contacting surfaces resulting from the sudden impact. Joints are also observed with no connections, which signify open circuits. Almost 25% of circuits were found open in the samples (after 384 h in a humid environment), which have suffered severe mechanical shock. Breaking of the conductive layer of the particle and exposing the underlying polymeric portion was also observed.

Recent advances in mechanical properties of anisotropic conductive adhesive film for microelectronic packaging

2015 ◽  
Vol 27 (4) ◽  
pp. 164-177 ◽  
Author(s):  
Lilan Gao ◽  
Hong Gao ◽  
Xu Chen
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Stress Amplitude ◽  
Microelectronic Packaging ◽  
Mean Stress ◽  
Adhesive Film ◽  
Content Type ◽  
Hygrothermal Aging ◽  
Anisotropic Conductive Adhesive ◽  
The Impact

Purpose – This review paper aims to provide a better understanding of formulation and processing of anisotropic conductive adhesive film (ACF) material and to summarize the significant research and development work for the mechanical properties of ACF material and joints, which helps to the development and application of ACF joints with better reliability in microelectronic packaging systems. Design/methodology/approach – The ACF material was cured at high temperature of 190°C, and the cured ACF was tested by conducting the tensile experiments with uniaxial and cyclic loads. The ACF joint was obtained with process of pre-bonding and final bonding. The impact tests and shear tests of ACF joints were completed with different aging conditions such as high temperature, thermal cycling and hygrothermal aging. Findings – The cured ACF exhibited unique time-, temperature- and loading rate-dependent behaviors and a strong memory of loading history. Prior stress cycling with higher mean stress or stress amplitude restrained the ratcheting strain in subsequent cycling with lower mean stress or stress amplitude. The impact strength and adhesive strength of ACF joints increased with increase of bonding temperature, but they decreased with increase of environment temperature. The adhesive strength and life of ACF joints decreased with hygrothermal aging, whereas increased firstly and then decreased with thermal cycling. Originality/value – This study is to review the recent investigations on the mechanical properties of ACF material and joints in microelectronic packaging applications.

scholarly journals Design Guidelines for Anisotropic Conductive Adhesive Assemblies in Microelectronics Packaging

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Melida Chin ◽  
S. Jack Hu ◽  
James R. Barber
Keyword(s):  
Contact Resistance ◽  
Adhesion Strength ◽  
Modulus Of Elasticity ◽  
Elastic Recovery ◽  
Electrical Contact ◽  
Design Guidelines ◽  
Conductive Adhesive ◽  
Bonding Force ◽  
Anisotropic Conductive Adhesive ◽  
Number Of Particles

Multiple parameters are involved in the design of anisotropic conductive adhesive assemblies, and the overlapping influences that they have on the final electrical contact resistance represent a difficult challenge for the designers. The most important parameters include initial bonding force F, number of particles N, the adhesion strength GA, and modulus of elasticity E of the cured resin. It is well known that as the bonding force increases, the contact resistance decreases. However, when the bonding force reaches a certain maximum value, the contact between conductive particle and conductive track is disrupted due to delamination of the cured resin during the elastic recovery. The authors have shown in previous studies that the delamination is caused by high residual stresses and that it largely depends on the adhesion strength of the assembly and on the modulus of elasticity of the cured resin. Additionally, the authors have provided a methodology to quantify the maximum threshold value of the bonding force for different numbers of particles trapped between mating conductive tracks. In this paper, the relationships between contact resistance R and each one of these parameters are systematically investigated to create diagrams that give regions of robust design. Given the number of particles and their size, adhesion strength, and modulus of elasticity of the resin, the required bonding force can be found in order to achieve a desired range in contact resistance.

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