Chapter 8 - Packaging Assembly Techniques

Abstract

A typical electronic package contains millions of transistors assembled in chips, resistors, diodes, capacitors, and other components. The package performs four main functions that include sound signal distribution and maintenance of signal integrity with minimum cross-talk, mechanical support to the entire assembly, provision of a path of least resistance to the flow of heat thus enhancing heat dissipation properties, and finally protection from the environment. In order to perform the different logical functions these components are connected to each other to form functional entities. To function, these circuits are supplied with electric energy, some of which is converted into thermal energy. An electronic object can function correctly if the package has good electrical, mechanical, thermal, and metallurgical properties. A proper selection of materials, processes, assembly techniques, board design, component layout, and operating procedures ensure a reliable product that is easy to manufacture. It is also desirable that the packaging occupies a minimum of space and weight. A typical surface-mount technology (SMT) process involves mounting electronic packages on the surfaces of the PCBs. SMT offers several inherent advantages such as the components are generally small and can be mounted on either side of the board, reduction in weight and size, more interconnections per unit area, better electrical properties, quicker signal propagation, and reduction in cost due to real-estate savings.