Thermo-mechanical characterisation of a nanosized particle filled underfill
This paper describes work carried out as part of a larger project aimed at the development of nanosized particle filled underfill material. Several characterisation experiments have been applied to study the influence of these particles on the curing behaviour and the thermomechanical properties such as the coefficient of thermal expansion, geltime, glass transition temperature, and modulus. Constitutive models are assessed for their ability to describe the observed behaviour
Prediction of mechanical stresses induced by flip-chip underfill encapsulants during cure
A constitutive model is presented for predicting the stresses in thermosetting resins during and after cure. An overview is given of the experimental techniques used for estimating the parameters in this model. The model is validated by comparing its predictions to a second set of measurements that has not been used for the actual parameter estimation. This validation shows that the model is capable of giving fair predictions of the measured stresses. The model is implemented in a commercially available finite element package and its use is demonstrated by applying it to the study of a flip-chip underfilling process.
Unidirectional hexagonal rare-earth disilicide nanowires on vicinal Si(100)-2×1
Rare-earth disilicide nanowires grown on vicinal Si(100) with a miscut of 2–2.5° toward the [110] azimuth at 600 °C were studied by scanning tunneling microscopy and compared with those grown on flat Si(001). In contrast to rare-earth disilicide nanowires grown on flat Si(100) surfaces, the nanowires grow unidirectionally along the [01̄1] direction of the vicinal Si(100) surface. Rare-earth disilicide nanowires form bundles composed of single nanowire units on both flat and vicinal surfaces. Yet, on the vicinal surface, the bundle width is comparable to the width of the terrace. The average nanowire length on the vicinal substrate is longer than that on the flat substrate. Scanning tunneling spectroscopy shows that the rare-earth disilicide nanowires have metallic properties.