Behavior of Anisotropic Conductive Film (ACF) Joint under Mechanical Shock

2005 ◽  
Vol 127 (4) ◽  
pp. 375-380 ◽  
Author(s):  
Rashed Adnan Islam ◽  
Y. C. Chan
Keyword(s):  
Contact Resistance ◽  
Flexible Substrates ◽  
Mechanical Shock ◽  
Conductive Layer ◽  
Anisotropic Conductive Film ◽  
Particle Deformation ◽  
Humid Environment ◽  
Conductive Film ◽  
Microscope Images ◽  
Scanning Electron

The contact resistances investigated by this study of ACF joints using Au∕Ni bumps and flexible substrates are found to be increased by the induced mechanical shock and also by the combined effect of heat/humidity and the mechanical shock. The samples humidified at 85°C/85% RH for 384 h, on which a load of 3.164 Kg was dropped four times from a height of 0.4 m, exhibit the most severe results. The contact resistance increases by 700%, which had been about 62 mΩ in the as-bonded condition. The samples without humidification showed a sluggish and gentle increase in contact resistance with the induced mechanical shock. The contact resistance was found to be increased by 400% after the sixth drop from a height of 0.5 m. Scanning electron microscope 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 the circuits were found open in the samples (after 384 h in a humid environment), which have suffered severe mechanical shock (load drops four times from 0.4 m height). Breaking of the conductive layer of the particle and exposing the underlying polymeric portion were also observed.

Reliability of Anisotropic Conductive Film Joints Using Bumpless Chip—Influence of Reflow Soldering and Environmental Testing

2005 ◽  
Vol 127 (2) ◽  
pp. 113-119 ◽  
Author(s):  
W. K. Chiang ◽  
Y. C. Chan
Keyword(s):  
Contact Resistance ◽  
Corrosion Mechanism ◽  
Anisotropic Conductive Film ◽  
Reflow Soldering ◽  
Environmental Testing ◽  
Polymer Hydrolysis ◽  
Conductive Film ◽  
Reflow Temperature ◽  
Environmental Test ◽  
Modulus Reduction

This paper presents the reliability of anisotropic conductive film (ACF) joint tested under reflow soldering and environmental test effect. The ACF joint behaved differently under different reflow soldering profiles. The lower reflow temperature resulted in more reliable ACF joints by maintaining low contact resistance. By contrast, high contact resistance was found in assemblies treated with higher reflow. Under humidity aging (85°C/85%RH), bumpless chips proved to be unreliable due to corrosion mechanism. Moreover, ACF had shown degradation in chemical and physical properties, including modulus reduction, Tg depression, polymer hydrolysis, and surface swelling after exposing to humidity aging. The deterioration in reliability of aged ACF joint during reflow process was mainly caused by hydroscopic swelling-induced stress of ACF.

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.

Moisture Effects on the Reliability of Anisotropic Conductive Film Interconnection for Flip Chip on Flex Applications

2005 ◽  
Author(s):  
Chunyan Yin ◽  
Hua Lu ◽  
Chris Bailey ◽  
Yan-Cheong Chan
Keyword(s):  
Contact Resistance ◽  
Flip Chip ◽  
Semiconductor Industry ◽  
Moisture Diffusion ◽  
Testing Time ◽  
Anisotropic Conductive Film ◽  
Conductive Films ◽  
Conductive Film ◽  
Moisture Effects ◽  
Conductive Particles

Anisotropic conductive film (ACF) which consists of an adhesive epoxy matrix and randomly distributed conductive particles are widely used as the connection material for electronic devices with high I/O counts. However, for the semiconductor industry the reliability of the ACF is still a major concern due to a lack of experimental reliability data. This paper reports the investigations into the moisture-induced failures in Flip-Chip-on-Flex interconnections with Anisotropic Conductive Films (ACFs). Both experimental and modeling methods were applied. In the experiments, the contact resistance was used as a quality indicator and was measured continuously during the accelerated tests (autoclave tests). The temperature, relative humidity and the pressure were set at 121°C, 100%RH, and 2atm respectively. The contact resistance of the ACF joints increased during the tests and nearly 25% of the joints were found to be open after 168 hours’ testing time. Visible conduction gaps between the adhesive and substrate pads were observed. Cracks at the adhesive/flex interface were also found. For a better understanding of the experimental results, 3-D Finite Element (FE) models were built and a macro-micro modeling method was used to determine the moisture diffusion and moisture-induced stresses inside the ACF joints. Modeling results are consistent with the findings in the experimental work.

Effects of the Thermocompression Bonding on the Microstructure and Contact Resistance for the Ultrafine Pitch Chip-on-Glass Packaging With Nonconductive Film

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Jianhua Zhang ◽  
Jinsong Zhang ◽  
Lianqiao Yang
Keyword(s):  
Contact Resistance ◽  
Bonding Temperature ◽  
Anisotropic Conductive Film ◽  
Bonding Parameters ◽  
Conductive Film ◽  
Geometric Size ◽  
Ε Phase ◽  
Thermocompression Bonding ◽  
Temperature And Pressure ◽  
Glass Packaging

Nonconductive film (NCF) is a challenging potential material to substitute the application of anisotropic conductive film in the ultrafine pitch chip-on-glass (COG) packaging. The NCF interconnection requires a high bonding temperature and pressure to form joints, and this causes new reliability concerns. This study investigated effects of the thermocompression bonding parameters on the microstructure and geometric size in the joints to a COG module packaged with NCF. The results revealed that the high temperature and pressure compressed the joints to become wider and shorter. A dual layer of intermetallic compounds consisting of AuSn2 (ε phase) and AuSn4 (η phase) was found in each joint. They were the two kinds of interphases with different melting points (AuSn2:309°C and AuSn4:257°C) during the interfacial reaction between Au and Sn. At the low temperature (below the melting point), the high pressure induced the residual inner stress to generate the cracks in the joints, and this also increased the contact resistance of the joints. The contact resistance increased with the pressure elevating at the same temperature and with the temperature degrading at the same pressure. In the COG packaging with NCF, a proper elevating of the bonding temperature could produce a stable direct connection with the low contact resistance.

Scanning Electron Microscope Induced Electrical Breakdown of Tungsten Windows in Integrated Circuit Processing

2004 ◽  
Author(s):  
David M. Shuttleworth ◽  
Mary Drummond Roby
Keyword(s):  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Contact Resistance ◽  
Integrated Circuit ◽  
Electrical Breakdown ◽  
Scanning Electron ◽  
Integrated Circuit Processing

Abstract Interaction of inline SEM inspections with tungsten window-1 integrity were investigated. Multiple SEMs were utilized and various points in the processing were inspected. It was found that in certain circumstances inline SEM inspection induced increased window-1 contact resistance in both source/drain and gate contacts, up to and including electrical opens for the source/drain contacts.

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