Direct chip attach Wire bonding

Further miniaturization is enabled by direct assembly of bare dies onto circuit carriers. This kind of component is electrically connected by wire bonding. Other methods for direct chip attachment are flip chip and tape automated bonding. All three methods require special equipment for processing and inspection. 

After attachment to the substrates, LED chips can be wire bonded or flip-chip bonded. If wire bonded (see section 1.2.1), the entire backside is available for heat dissipation. In flip-chip bonded formats, however, the thermal path is through the bumps only. Therefore, from a thermal dissipation viewpoint, direct die attachment to a heat spreader followed by wire bonding is preferred. Regardless of the interconnect approach, package materials having high thermal conductivities are required. 

CSP was introduced in Japan in the early 1990s and in the United States soon thereafter as a less expensive alternative to MCMs. According to IPC/JEDEC J-STD-012 definition, CSP is a single-die, direct-surface mountable package with an area of no more than 1.2 times the original die area. CSPs come in many forms— wire-bonded, flip-chip, leaded, and EGA. A typical wire-bonded CSP packaging process (Fig. 4.5) starts with the attachment of the die on... 

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