| Summary: | 碩士 === 逢甲大學 === 航空工程所 === 92 === Nowadays, the favor of electronic devices with diverse functions, portability and very high performance has pushed the design of IC packages to a new era with higher I/O densities, smaller packaging size, and faster operation frequency. The chip-on-glass (COG) technology that can provide very fine-pitch interconnection and high throughput has been extensively applied in many applications, such as liquid-crystal-display (LCD) panels. The key technology in the COG is the use of an epoxy-based adhesive to achieve the interconnection between LSI chips and glass substrates for electrical conduction, mechanical bonding and/or thermal passage. Adhesive materials available for the interconnection include the isotropic conductive adhesive (ICA), the anisotropic conductive adhesive (ACA) and the non-conductive adhesive (NCA).
In spite of the success of the COG technology, the associated yield and reliability issues remain in concern. Yield and reliability are two of the most important issues in IC packaging, and in general, the poor yield and reliability can be largely resulted from the process- and/or thermal-induced deformations and stress/strain behaviors, which may be in connection with different failure modes. The underlying goal of the study is to explore the thermal-mechanical behaviors of the COG technology during manufacturing process and temperature elevation. An effective modeling methodology that integrates numerical modeling and experimental validation is proposed to qualitatively and quantitatively characterize the associated thermal-mechanical behaviors. The techniques for experimental validation include: 1) the electrical contact resistance measurement using a four-point probe method and an equivalent circuit, and 2) a microscopic Twyman-Green moiré interferometry measurement for quantifying the process-induced thermal-mechanical behaviors. Furthermore, the numerical modeling employs three-dimensional (3-D), nonlinear, contact finite element (FE) modeling that combines a process-dependent thermal-mechanical simulation together with the exclusive “death and birth” modeling technique. In this investigation, two types of COG technology are considered, which are the ACF type and the NCA type, respectively. At last, through parametric FE study, the dependence of the thermal-mechanical behaviors of the COG assembly on a number of geometry and material design parameters is identified, and eventually, a design guideline for better management of the process-induced thermal-mechanical behaviors of COG technology is established.
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