Fundamentals of Bonding Technology and Process Materials for 2.5/3D Packages

Abstract

A few leading semiconductors recently released high performance products adopting 3-dimensional (3D) packaging technology moved to the forefront in the electronic packaging industry in order to meet the requirements of device performance and form factor driven by consumer electronics trends. Even after 3D commercial products were produced into electronic markets, the leading companies still struggle to demonstrate a competitive 3D packaging assembly process compared to traditional packaging assembly process. In the 3D packaging process, bonding technology among technical challenges is most problematic. The in situ bonding technology referred to as Thermal Compression Bonding (TCB), typically controls force, temperature, and displacement simultaneously, which are applied to packages when to reflow microbump solder interconnect of 3D TSV die. Using the in situ bonding technology, a bonding cycle can be completed in several seconds, which means that bonding equipment and process materials sustain heavy process stress due to rapidly changing thermal conditions. Thus, this chapter reviews the newly developed TCB technology and related assembly materials to provide engineering sciences, fundamentals of the bonding technology, and process materials for advanced application. First, this chapter compares the new technology with traditional assembly process regarding process, material, and equipment. Next, the subsection presents traditional analytical methods and practical fundamental investigation methods to characterize material formulation. Then, a comprehensive analysis is presented to provide the pros and cons of major assembly building blocks. Consequently, this chapter would help to understand how to design assembly building blocks that are adequate to the package configuration. In addition, this chapter introduces a hybrid bonding technology and alternative interconnect technology to overcome throughput challenge induced by TCB bonding mechanism used for 3D stacking.