Polycyanate based die attach adhesives have found increased popularity for many applications including hermetic as well as plastic molded IC packages. Principal advantages of cyanate thermoset are high heat resistance, low outgassing of volatiles, and easily modified to satisfy various application requirements. This paper reviews the development of various types of adhesives designed to meet advanced semiconductor packaging requirements. Generally speaking, the hard, rigid adhesives are used on rigid, non-bending substrates such as alumina, copper heat sink, etc. While the soft, flexible adhesives find applications for flexible substrates such as thin copper leadframes, polymer laminates.