Abstract
Area Array microelectronic package with small pitch and large I/O counts is now widely used in the ceramic packaging of microelectronics Integrated Circuit (IC). This kind of Land Grid Array (LGA) device cannot be directly soldered on Printed Circuit Board (PCB). In order to mount them on PCB the LGA device back end is mostly terminated with solder columns (CGA device) or with solder balls (BGA device). For space application CGA and BGA ceramic devices are prone to early failure due to harsh environment. Indeed vibration and shock during launch as well as thermal cycling in orbit induces a high level of stress in the solder joints between board and device. Such high level of stress can ultimately cause the failure of one of the solder joints causing permanent functional electrical failure. As the trend for next generation of ceramic IC device is to increase their sizes and their density of I/O, susceptibility to mechanical and thermal loading grows even more. This statement is in contradiction with the high level of reliability required for space application. To overcome this situation CNES has taken the lead with space users and space connector manufacturers to develop for space application a reliable solderless solution that will enable to easily mount on board the actual and the next generation of ceramic IC package. This solderless solution consists in using a thin connector interposer between the ceramic LGA device and the board. A clamping system is used to hold and keep aligned on the board the stacking composed of the ceramic device and the interposer connector. This solderless solution has been evaluated according to the European space standard and has demonstrated a high robustness to harsh environment making this solution compliant for space application.
Published Version
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