Abstract
Parallel to the development of new lead-free solders, electronic packaging has gone through a considerable evolution. A redistribution of layers allows the increase of functionality by increasing the number of inputs/outputsin the packagewhile reducing the size. The reliability of the package is strongly influenced by the reliability of the interconnects. During production and service life, there are thermal processes involved that may lead to thermal fatigue. In this work, a two-dimensional finite elementmodel of a Fan-Out Wafer Level Packaging (FO-WLP) was built, and simulations of thermal test cycles were carried out varying the solder interconnect material: SAC305, SACQ, SACR, orInnoLot. A thermal oscillating load from –40°C to 125°C was applied to the packaging for three hours.State of the art concerning solder joint reliability models based on creep behavior reveals the benefit of using energy-based parameters, as cycles to failure are inversely proportional to the average creep strain energy density.Based on theaverage creep strain energy density simulation results, the reliability of the package withdifferent solderswas compared.The qualitative results suggestthat SACQ has a significant advantage in the operational lifetime compared toSACR, InnoLot, and SAC305.
Highlights
Recent regulations on Waste from Electrical and Electronic Equipment (WEEE) and Restrictions of Hazardous Substances (RoHS) have limited the usage of Pb in electronic applications [1], [2]
A two-dimensional finite elementmodel of a Fan-Out Wafer Level Packaging (FO-WLP) was built, and simulations of thermal test cycles were carried out varying the solder interconnect material: SAC305, SACQ, SACR, orInnoLot
A thermal oscillating load from –40°C to 125°C was applied to the packaging for three hours.State of the art concerning solder joint reliability models based on creep behavior reveals the benefit of using energy-based parameters, as cycles to failure are inversely proportional to the average creep strain energy density.Based on theaverage creep strain energy density simulation results, the reliability of the package withdifferent solderswas compared.The qualitative results suggestthat SACQ has a significant advantage in the operational lifetime compared toSACR, InnoLot, and SAC305
Summary
Recent regulations on Waste from Electrical and Electronic Equipment (WEEE) and Restrictions of Hazardous Substances (RoHS) have limited the usage of Pb (lead) in electronic applications [1], [2]. One of the critical lead-contained components in the electronics industry had been the soldering material; the eutectic Sn-Pb (tin-lead) solderhad to be replaced by lead-free soldering materials. A significant change in the composition of the soldering material translates to an increase in the melting temperature that should not compromise the electronic device performance and reliability. Varying the composition of the alloys, different SAC solders have been commercialized (e.g., SAC305, SAC405, SAC105)[5]. Thermal requirements have been defined for Integrated Circuits (ICs) that undergo harsh working environments where temperature loads may reach over 150°C [6]. New solder materials, called doped-SAC or SAC-X, were developed[7]
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