Pusat Pengajian Kejuruteraan Mekanikal - Tesis

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Browsing Pusat Pengajian Kejuruteraan Mekanikal - Tesis by Author "Alim, Md. Abdul"

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    Encapsulation process of polymer for led packaging
    (2021-12-01)
    Alim, Md. Abdul
    Several developments and innovations have reported strengthening the reliability and efficiency of these devices to speed up the LED packaging industry for the past few years. To develop a sustainable LED packaging process, die attachment and encapsulation shape are key factors. Epoxy based non-conductive adhesive (NCA) is popular die attachment material. Though NCA have many benefits so, an investigation on the suitable shear strength, adhesive thickness, and adhesion area are essential for die attachment process. Normally, high viscous epoxy resin is used as encapsulation material. A proposed low viscosity epoxy encapsulation shape can represent a new milestone for low-cost LED fabrication. In this work, the relationship between adhesive thickness and shear strength developed in chip and substrate joint is evaluated by using different adhesive applicator. Surface morphology of chip and substrate are also studied by using the SEM, EDS, and image processing software. The result indicated that the suitable shear strength 37.42 N/mm2 obtains at 24 µm thickness of the adhesive layer. A new moldless dispensing method for forming dome shaped encapsulation is studied. Luminous intensity of LED is determined by mixing verity of weight % of phosphor with the epoxy and variation in shape of encapsulation The results show that this method can produce the lenses with high aspect ratio (height over radius) on substrates of different sizes. The improvement of light output was found about 2.37% for dome shaped (average H/R value 0.71) encapsulation. This experimental work is a good guideline to master the geometric shape of encapsulation for further development and to choose technological criteria for LED packaging.