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The chip-on-glass (COG) technique using anisotropic conductive film (ACF) has been developed for liquid crystal display (LCD) panels with excellent resolution and high quality for several years. However, many serious manufacturability and reliability issues were observed from previous studies. In those, delamination occurring at the ACF interface is one of the common concerns. Few works presented analysis of delamination mechanism through the whole COG bonding process with the combination of LCD module scale and ACF interconnect scale. In this paper, the delamination mechanism of COG/ACF interconnection was studied by using finite element analysis. Equivalent block and global-local modeling methods were implemented with nonlinear elastic-plastic and sequential coupled thermal-mechanical analysis. The critical parameters of the COG bonding process and geometry of integrated circuit (IC) and glass were investigated to understand the mechanism of ACF delamination. It was found that the delamination could be reduced by decreasing the temperature difference between bonding head and glass substrate or using thin and short IC. The local model analysis revealed that the interface of glass/ACF epoxy encountered the higher stress than that in the interface of IC/ACF epoxy and had the higher possibility to delaminate. Therefore, increasing the bonding-strength between glass and ACF epoxy is the direction to reduce the probability of ACF delamination.

The effects of Bi addition on the growth of intermetallic compound (IMC) formation in Sn-3.8Ag-0.7Cu solder joints were investigated. The test samples were prepared by conventional surface mounting technology. To investigate the element diffusion and the growth kinetics of intermetallics formation in solder joint, isothermal aging test was performed at temperatures of 100, 150, and 190 °C, respectively. The optical microscope (OM) and scanning electron microscope (SEM) were used to observe microstructure evolution of solder joint and to estimate the thickness and the grain size of the intermetallic layers. The IMC phases were identified by energy dispersive X-ray (EDX) and X-ray diffractometer (XRD). The results clearly show that adding about 1.0% Bi in Sn-Ag-Cu solder alloy system can refine the grain size of the IMC and inhibit the excessive IMC growth in solder joints, and therefore improve the reliability of the Pb-free solder joints. Through observation of the microstructural evolution of the solder joints, the mechanism of inhibition of IMC growth due to Bi addition was proposed.

The package technology has matured significantly over the past several years, shifting from conventional components and direct board level assembly to chip or package level system integration. Two major commonly used approaches are System-on-Chip (SoC) and System-in-Package (SiP). Package-on-Package (PoP) that integrates logic die in the bottom package and memory die in the top package into a single 3D package is one of the promising SiP solutions.

In this paper, a novel interferometric method with a wide range of sensitivities, called holography quasi projection moire method, is presented. It combines the features of the varied double projection moire method and the holographic interferometry method. This technique has been used to study the various failure modes, such as spallation, delamination, 1D buckle, 2D buckle, and crush, in microelectronic packaging film/substrate modules. The experimental phenomenon and fracture mechanism for various failure modes are presented and analyzed.

The reverse multiplicate technique of moire interferometry is introduced. In this method, shear reverse, carrier wave, multiplicate and optical Fourier processing technique are combined cleverly and applied successfully to the moire interferometry. When the deformed patterns of moire interferometry with carrier wave are multiplied using carrier wave frequency, the deformed information of the specimen are multiplied successfully at same time. As a final experimental result, the moire fringes are multiplied clearly by 16 times, and measuring displacement sensitivity is increased from 0.4 micrometer to 0.025 micrometer. This method is applied to measure in-plane displacement fields around interlayer crack- tip of metal film/ceramic substrate under different thermal loading. From experimental displacement fields, the strain fields around interlayer crack-tip can be obtained as well. The displacement singularity of crack-tip is analyzed. The experimental results show that the displacement singularity of interlayer crack-tip under thermal loading is exponential singularity related with the material properties of the specimen.© (1997) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.