Introduction

Abstract

Microelectronic packaging is the science of providing interconnections and a suitable operating environment for microelectronic circuits [1.1]. Packaging involves the critical activities of interconnecting, powering, cooling, and protecting semiconductor chips. The technologies, and materials available for microelectronic packaging are numerous. Figure 1.1 diagrams the electronic module assembly schemes in use today. All methods begin with chips (also referred to as bare die) and conclude with a completed module which could be interconnected within a larger system. The multiple levels shown in Figure 1.1 are often referred to as the packaging hierarchy. The number of levels within the hierarchy varies depending on the module assembly path chosen. Figure 1.1 does not show the complete packaging hierarchy. Traditionally, the complete hierarchy could include other elements such as a board or backplane level to which modules or cards are connected, a cable level (sometimes called gate level) in which boards are connected by cable, and a frame or box level which contains the entire system [1.1].