A Novel Die Attach Material Having High Die Shear Strength and High Heat Resistance for Brighter LED Device

Die attach material for LED package plays a significant role in performance and reliability of LED device. There are two common materials used for die attach in the LED package and each material has its own characteristics. Epoxy material which is well balanced industrial material and used for a wide variety of applications, offers high die share strength. However, epoxy material cannot used in high temperature because it turns yellow and shows low transmittance at high temperature. By comparison to epoxy, silicone material shows high heat resistance. Because of higher heat resistance, silicone material is the first choice for high brightness LEDs for now. However, as the high brightness of the light elements in recent years, the die attach material exposure to high heat from the light for a long time, failures such as cracks and delamination has occurred. Therefore, development of the material can be obtained with high die share strength and high heat resistance has been desired. In this paper, we propose new concept of the die attach material that offers high die shear strength and high heat resistance. In order to achieve these properties, we use the polysilsesquioxane (PSQ) as the base compound. PSQ is a new organic-inorganic hybrid material and it has high flexibility since the inorganic structure shows excellent transparence and heat resistance, and the organic functional group gives good reactivity. To increase the die shear strength and to enhance anti-delamination performance, we add unique additives such as silane coupling agents and silicone powders into the base compound of PSQ. As a result of evaluation, our newly developed material shows equal heat resistance performance as silicone material, and also shows high die shear strength, more than twice as high as silicone material.