The use of anisotropically conductive adhesives (ACA) for the direct interconnection of flipped silicon chips to printed circuits (flip chip packaging), offers numerous advantages such as reduced thickness, improved environmental compatibility, lowered assembly process temperature, increased metallization options, cut downed cost, and decreased equipment needs. Despite numerous benefits, ACA film type packages bare several reliability problems. The most critical issue among them is their electrical performance deterioration upon consecutive thermal cycles attributed to gradual delamination growth through chip and adhesive film interface induced by CTE mismatch driven shear and peel stresses. In this study, warpage of the chip is monitored by real time moiré interferometer during –50oC to +125oC temperature range. Moreover, reduction in chip warpage due to increase in delamination length is obtained as in function of thermal fatigue cycles. Finally, a new model to predict damage level of ACA package and remained life is proposed and developed.

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Carbon nanotubes (CNTs) have remarkable mechanical strength, electrical conductivity, and thermal conductivity in spite of low density. Recently, CNT / epoxy composite have been widely investigated in terms of fabrication process and material characterizations. However, there have been few previous studies on B-stage film type CNT / epoxy composites for electronic packaging applications. B-stage film type CNT / epoxy composite films were fabricated and their properties were characterized for electronic packaging applications. The most important issue on fabrication on B-stage epoxy based films were uniform dispersion of CNTs in an epoxy resin. In this study, using optimized dispersion process, CNT / epoxy films were coated on a releasing film and subsequently dried by the comma roll coating method. Curing behavior of B-stage films, mechanical properties and electrical properties of fully cured films were characterized as a function of CNT contents. According to experimental results, CNTs lowered the curing activation energy of epoxy resin and increased electrical conductivity of epoxy resin.

Among many factors that influence the reliability of a flip-chip assembly using NCF interconnections, the most effective parameters are often the coefficient of thermal expansion (CTE), the modulus (E), and the glass transition temperatures (Tg). Of these factors, the effect of Tg on thermal deformation and device reliability is significant; however, it has not been shown clearly what effect Tg has on the reliability of NCF. The Tg of a conventional NCF material is approximately 110°C. In this study, a new high Tg NCF material that has a 140oC Tg is proposed. The thermal behaviors of the conventional and new NCFs between -40oC to 150oC are observed using an optical method. Twyman-Green interferometry and the moiré interferometry method are used to measure the thermal micro-deformations. The Twyman-Green interferometry measurement technique is applied to verify the stress-free state. The stress-free temperatures of the conventional and new Tg NCF materials are approximately 100oC and 120oC respectively. A shear strain at a part of the NCF chip edge is measured by moiré interferometry. Additionally, a method to accurately measure the residual warpage and shear strain at room temperature is proposed. Through the analysis of the relationship between the warpage and the shear strain, the effect of the high-Tg NCF material on the reliability is studied.

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