| Summary: | 碩士 === 逢甲大學 === 航太與系統工程所 === 97 === Nowadays, portable electronic devices are being pushed toward the miniaturization and flexibility. The Ultra Thin Chip on Flex (UTCOF) technology is a very promising and feasible packaging solution for attaining the goals due to its high flexibility, and more importantly compatible to the current semiconductor fabrication and packaging industry.
In this study, the technology implements an epoxy-based anisotropic conductive film(ACF), which are composed of an adhesive polymer resin and conductive particles of metal-coated polymer particles. The ACF formed fine–pitch and reliable interconnects of bumps on substrates. Poor yield and reliability can be largely resulted form the external force or its thermal-mechanical behaviors. A process-dependent finite element (FE) simulation methodology that integrates both process-dependent and thermal-mechanical behaviors for the process simulation through three-dimensional (3-D),nonlinear FE analyses together with the so-called “death and birth” simulation technique. In order to find a design guideline for better thermal-mechanical performance, parametric FE study is performed, which investigates the dependence of the warpage of the substrate ,the contact stress at the interconnects and the peeling stress at the ACF. The considered design variables include geometry parameters, material constants and process factors. Furthermore, Taguchi method is applied to acquire the most important combination of these factors. Subsequently, a response surface methodology (RSM) combined with the Face Central Composite Design (FCCD) experimental design plan is performed to derive an approximate mathematical model of the objective function in terms of the most essential combination of design variables. Finally, the validity of the proposed process-dependent FE simulation methodology is also confirmed through Micro Figure Measuring Instrument for the warpage of the chip.
The variable of the contact pressure and the peeling stress are the key point of the packaging which is on four point bending test or static bending test. In order to find a better performance, parametric FE study is performed, which investigates the dependence of the contact stress at the interconnects and the peeling stress. Besides, using Taguchi method and response surface methodology to find the optimal design. In the end, to determine the appropriate for the contact which can be contrast by electric resistance and the result of the FE simulation methodology.
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