Microelectronic packaging has been accelerating towards adoption of novel solutions that offer lower cost, higher electrical performance, and better reliability. Flip chip technology lends itself excellently to these goals. The development of anisotropic and isotropic conductive adhesives (ACA & ICA respectively) as an alternative to solder bumps has received extensive attention in flip chip packaging as it offers an array of advantages like finer pitch interconnects, green processes, low cost,

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... and low temperature processing. The Anisotropic Conductive Adhesive (ACA) is one promising candidates which also shows potential for future pitch reduction. However, the main concern with anisotropic conductive adhesive interconnection is its long-term reliability. The degree of spread of the conductive particles between the 50μm bump pitch and substrate pad, determined by the amount of pressure applied during the bonding process, has a great influence on the contact resistance of the ACA joints. As a result, nanosized conductive particles are preferably used in the finer pitch ACA application (5μm bump pitch) to enhance reliability and performance. Therefore, the main objectives of this project are to develop nanosized hollow silica microspheres and encapsulate nickel with these microspheres. By using these encapsulated nickel particles as fillers in ACA interconnection, long-term reliability of ACA joints can be improved. In this study, one of the objectives was the development and synthesis of sub-micron nickel powders. Nickel was the conductive filler taken into consideration because of ATTENTION: The Singapore iii the many advantages it offered. Hydrothermal reduction of nickel sulphate using hydrazine was the main synthesis route. The nickel salt concentrations were varied to investigate their influence on nickel sizes. It was found that reducing the salt concentration resulted in size reduction; however, the trend was non-linear. Spiky spherical nickel particles were produced ranging from 300 nm to 1 micron. The spiky morphology may have a detrimental effect on the conductivity of the ICA & ACA flip chip interconnect due to its smaller contact surface and propensity towards oxidation. The morphology of the nickel surface can be changed by annealing the particles between 270°C and 360°C for 4 to 12 hours. A smoothening effect leading to more or less smooth spherical particles along with an increase in conductivity was observed after annealing at 360°C for up to 12 hours. An analytical model considering surface diffusion is established here to describe the temperature activated and energy minimization driven smoothening of the Ni particles. An interfacial synthesis method was used to synthesize thermally stable hollow silica microspheres. The structure was synthesised at room temperature from a vortexed mixture of water and droplets of tetraethoxysilane (TEOS) containing aminopropyltriethoxysilane (APTES): droplets were stabilized with the surfactant cetyltrimethylammonium bromide (CTABr) to produce silica shells. The results showed that the process parameter (stirring speed) and surfactant/chemical chemistry have great effects on size of the hollow particles. The sizes of hollow silica were observed to decrease with increasing stirring speed. When the percentage of APTES ATTENTION: The Singapore iv was increased from 10mol% to 15mol% of the total ethoxysilane used, the results gave an approximately hundred-fold decrease in the size of hollow spheres. Final experiment of this study also showed a successfully encapsulation of nickel particle with hollow silica spheres. This material would be favourably to be used as filler in ACA flip chip interconnections. ATTENTION: The Singapore