Author: Shoji Uegaki Company: Kyocera Corporation Date Published: 8/23/1998
Surface Mount International
Abstract: The application of Chip Scale Package (CSP) has drastically increased due to its small package size. Especially mobile equipments such as; digital camcorder, cellular phone, Personal Digital Assistance tools (PDA), and Notebook PCs have been achieving their miniaturization by utilizing CSPs. Ceramic is one of the materials utilized for the carrier of CSP, and is able to provide an optimum cost and performance solution. For the 2nd level (Carrier to PWB/Printed Wiring Board) interconnect, Thermal Coefficient of Expansion (TCE) mismatch between ceramic and PWB is said to be the main concern for the reliability. It is important to consider that the size of package is relatively small, and the high reliability can be optimized by design and assignment of solder pad. In addition, improvements through the use of a new joint structure can be realized. This paper will describe the advantages and the reliability of ceramic CSP, especially for 2nd level reliability which includes optimization techniques and enhancements.