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.

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.

Investigating the Deformation, Breakage and Number on Conductive Particle of Flim-on-Glass Packaging Using Anisotropic Conductive Film Bonding

2017 ◽  
Vol 886 ◽  
pp. 97-101 ◽  
Author(s):  
Chao Ming Lin ◽  
Yung Chuan Chiou ◽  
Chun Yi Chu
Keyword(s):  
Side View ◽  
Anisotropic Conductive Film ◽  
Conductive Particle ◽  
Field Of Vision ◽  
Fine Pitch ◽  
Conductive Film ◽  
Bonding Properties ◽  
Free Material ◽  
Conductive Particles ◽  
Glass Packaging

Anisotropic conductive film (ACF), is a lead-free material that is commonly used in fine-pitch interconnect manufacturing to make and maintain the electrical and mechanical connections between the micro-electrodes. A key issue about the circuit conductivity is the deformation, breakage, and number of conductive particles in the ACF packaging. For the field of vision, the Film-On-Glass (FOG) assembly on the glass-side is used to obtain excellent images in experimental observation. This paper utilizes the microscope technology to investigate the bonding properties of the conductive particles, and consider the electrical resistance effects after packaging. The results show the deformation shape, breakage type, and number of conductive particles will be quantitatively affect the electrical performances, and one can measure the area, diameter, and roundness of the deformed particles’ projection in the glass-side view to evaluate the ACF packaging quality.

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.

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.

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