Development of a high reliability and large volume manufacturing assembly process for a stacked memory package

The demand for multiple features in today's electronic products, coupled with the on-going trend for smaller and lighter devices, has lead to the ever-increasing component densities of printer circuit boards (PCB). Consequently, new and innovative ways to use existing PCB area is imperative. One method is to use stacked leaded packages for memory devices. Although this idea has been around for several years in small handheld applications, their usage on large, thick mother boards for telecomm applications have not been widely adopted. Several challenges exist and must be addressed prior to large-scale production. This paper addresses three manufacturing issues that arose during the development cycle of the product. In addition, the long-term reliability of the stacked component is also discussed.