Working Temperature Characterizations for Die Attach Films in Stacked-die Process

Following the strong demand of high-performance and miniaturized electronic devices with reduced process cycle time, the die attach film (DAF) has become a popular option for the die attach process of stacked-die packages in the semiconductor assembly industry. The working temperature of a die attach process is crucial to assembly yield and package reliability. However, as the number of die stacks increases, the die attach process with DAF may encounter a technical bottleneck since the working area is gradually away from the heat source. In this study, the thermal effect from bottom heating of plural-die-stack structures was investigated through transient thermal analysis as well as temperature measurements in an actual stacked-die process. It is clear from numerical and experimental results that as the number of dies in the die-stack structure increases, the time required to reach a working temperature for DAF increases significantly.