Numerical and experimental studies of heat transfer phenomena in microelectronic packaging.

摘要

In this thesis, two important heat transfer processes with electronic packaging applications--plasma arc discharge heat transfer and phase-change heat transfer are studied by numerical simulation and experimental methods. With plasma arc discharge heat transfer, the conservation equations for charged particle densities, electron temperature and Poisson's equation for the self-consistent electric field are solved simultaneously taking into account the potential drop in the gap during the discharge. The current flux and the heat flux to the wire are calculated. With phase change heat transfer, the heating and melting processes of the wire electrode during the ball formation process are simulated. These studies have direct applications in the manufacturing of semiconductor packaging equipment.; Several design aspects of the wire-bonding process will also be studied. Various designs for an auxiliary wand electrode used in the discharge will be studied by comparing the initial electric field intensity at the onset of the electronic flame off (EFO) discharge. The design improvement of a fine-pitch capillary is also proposed by considering the smallest symmetric ball size which can be formed from a bent tip wire.; A wide spectrum of numerical and experimental techniques are used as part of this research. Numerical methods including finite difference, control volume, finite element, and boundary element methods are employed in the research as well as CFD packages such as FIDAP and ANSYS. Laboratory studies required electronic data recording by high speed digital memory oscilloscopes, chemical etching, and SEM examination of the ball and wire samples.; The numerical results obtained from the arc discharge simulation and the ball formation simulation are in good agreement with experimental data. The current and heat flux to the wire obtained from the arc discharge simulation are close to the findings of the experiments. The calculations of ball size and temperature distribution along the wire from the ball formation simulation agreed very well with experimental data. This is shown by examining the ball size and grain structure of the wire which has gone through the heating and cooling process.