Reliability Studies for Package-on-Package Components in Drop and Shock Environments

The consumer electronics industry stands at a critical juncture where manufacturers strive to incorporate more functionality in smaller packages. In the highly competitive consumer electronics market, a continued demand for products with smallest possible form-factor yet high functionality has led to the proliferation of 3D packaging technologies. Package-on-Package (PoP) architectures, in particular have attracted a lot of interest, especially in portable electronics industry. The advantages of these stacked 3D architectures include simplified and compact design, savings of board space allowing for more package landings, reduced pin counts and optimized production costs. While a lot of recent research, in the field of PoP architectures has been focused on development of optimum process flows and warpage control during reflow, the effects of reflow parameters on the quality of PoP build and the associated reflow defects including warpage have not been extensively researched. Additionally, studies on reliability issues associated with PoP assemblies in drop and shock environments are scarce. Since PoP architectures find their applications mainly in portable electronics, which are susceptible to frequent drops and careless handling at the hand of the consumer, the reliability of PoP architectures in environments representative of the real world is critical to their success in the industry. In this study, Single component PoP test vehicles have been fabricated as per JEDEC standards for quantifying the reliability of PoP packages in drop and shock. Daisy chained double-stack PoP components have been used to identify failure for subsequent drop/shock performance analysis. Experimental strain data acquired using Digital Image Correlation and high speed continuity data- for identifying failure has been used in conjunction with validated FE simulations of drop test events; for development of life prediction models for PoP architectures. Validated node based global-local FE simulations are used to predict strains in critical solder balls in both layers of the PoP stack. The drop/shock reliability studies and life prediction models presented in this work, present an insight into PoP failures and eliminate the need for exhaustive testing procedures.