Low profile CSP BGA warpage improvement

With the popularity of the mobile and handset electronic product, there is a stringent requirement on IC package size, weight and thermal/ mechanical integrity. To be smaller, lighter and faster, traditional IC packaging is undergoing an evolution to achieve further miniaturization. Less than 1.0mm CSP BGA with die to package ratio larger than 0.78 was developed to provide such a miniaturization solution to mobile electronic product manufacturer. A series of packaging challenges were encountered when trying to scale down the traditional BGA packages, DAF (die attach film) heating induced strip warpage and post mold cure strip warpage are two key issues which have great impact on package manufacturability. Frequent substrate alignment alarm during die bonding, missing ball during ball attach process and insufficient sucking vacuum during saw singulation are three key showstoppers in qualifying this package for mass production. Thermal mechanical simulation was conducted to analyze the CTE/modulus mismatch induced mold strip warpage, Substrate was re-designed and new compound were evaluated based on the improvement direction given through simulation analysis. Full auto assembly operation was achieved through process/ material improvement for this low profile CSP BGA package.