Since the introduction of Chip Scale Packages (CSPs) only a few short years ago, they have become one of the biggest packaging trends in recent history. There are currently over 50 different types of CSPs available throughout the industry, and the numbers are increasing almost daily.
Intel® Flash Memory products began using CSPs in the µBGA* package a few years ago and have expanded into multiple types of CSPs in order to meet the needs of new product functionality and applications. Currently, the majority of Intel's CSPs are used for flash memory products. However, other types of Intel products are beginning to take advantage of the benefits of CSPs as well.
CSPs are evolving so rapidly, that by the time you read this chapter, there will probably be new package information and design considerations to take into account. Intel has attempted to include as much as possible in this chapter, reviewing many different areas such as package information, application considerations, printed circuit board (PCB) design, and manufacturing tips and tools. However, since CSPs are continually evolving, the contents of this chapter will continue to evolve. Therefore, until new versions of this package guide are printed, new CSP information and manufacturing considerations for Intel Flash Memory products will continue to be updated in the Flash Memory CSP User's Guide on the WWW at: http://developer.intel.com/design/flash/packtech/index.htm.
There are many reasons why CSPs have been so well accepted within the industry. One of the biggest advantages of CSPs is the size reduction of the package vs. more traditional peripherally leaded packages. This is mainly due to the Ball Grid Array (BGA) design of the package. By designing all interconnects under the package in the BGA style, you can increase the number of interconnects while saving PCB routing space. Other manufacturing advantages of CSPs include the self-alignment characteristics during PCB assembly reflow and lack of bent leads which cause coplanarity issues. Both of these CSP features increase PCB assembly yields and lower manufacturing costs.