Mouser - White Papers

Mouser Electronics White Paper Semiconductor technology was at the root of the technological revolution that changed the world in the second half of the twentieth century. The development of naturally occurring elements and compounds like silicon or gallium arsenide (GaAs), with conductivity values that fell between conductors and insulators, enabled the creation of the transistor and the integrated circuit. Though powerful and ubiquitous, these semiconductor devices are delicate components whose functionality and life cycles may be impaired by an electrical short, overheating, or exposure to particulate matter. Therefore, they require protective packaging solutions to ensure optimal performance. Certain metals like aluminum, high- temperature plastics like siloxane polyimide, organic substrates like epoxy resin, and some ceramic composites can all be used to construct durable protective casings for semiconductors that don't adversely affect conductivity or performance. As electronic applications and devices continue to evolve, so too has printed circuit board (PCB) design and manufacturing. The demand for greater component density on PCBs has driven the development of innovative packaging methods and attachment techniques, enabling the use of both sides of a PCB and significantly enhancing functionality within a compact form factor. Through new soldering methods and advancements in automated manufacturing processes, PCB design and assembly have become so intricate that automated inspection systems are often required to ensure the integrity and reliability of components and connections. In this paper, we'll explore the genesis and evolution of semiconductor packaging technology, from the early days of through-hole assembly to the advent of surface-mount technology like enhanced surface- mount power (eSMP ® ), dual flat no-leads (DFN), and FlatPAK ™ 5 x 6 packaging solutions from Vishay Intertechnology, Inc. Overview of Packaging Technologies Historically, packaged semiconductors were attached to PCBs by running leads (or pins) through apertures in the board (Figure 1) and then soldering them to either side—a method known as through-hole assembly. By plating these apertures with conductive materials, developers could make connections between different components on the board, even if they were not directly next to each other. Although through-hole technology has largely been phased out of PCB design and manufacturing in the last thirty years, it's still employed in more robust designs and components that require increased mounting strength, better heat dissipation, and greater resistance to mechanical stress Figure 1: View of a typical through-hole package with a heat sink. (Source: Mouser Electronics) As technology advanced, the need for more compact and efficient designs led to the development of surface-mount technology (SMT) in the 1960s. Through gradual growth and development, SMT became widely adopted across the industry in the 1980s. The advent and proliferation of SMT allowed developers to fit more components onto a single PCB and reduce the overall size of their complete design. Surface-mount devices (SMDs) are now the standard in PCB manufacturing, and the technology (Figure 2) is constantly evolving to meet the needs of engineers looking for optimal performance in increasingly smaller form factors. Figure 2: Example structure of an SMD transistor. (Source: Mouser Electronics) SMDs are typically lighter and considerably smaller than similar through-hole devices, a significant factor in the production of handheld electronics. SMT is faster, more efficient, and less costly to manufacture than through-hole technology, as it allows for greater automation in the manufacturing process. Additionally, without the need to drill holes in the board and bend and solder pins, the manufacturing process is shorter and simpler, with fewer mechanical errors and reduced downtime. The increased rate of production and more reliable manufacturing processes make SMDs more cost-effective and more reliable than their predecessors.

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