Warpage Prediction of Fine Pitch BGA by Finite Element Analysis and Shadow Moire Technique
Warpage is one of the major concerns in manufacturing BGA, CSP, POP or QFN based array packages because a reasonably flat package is critical to successful singulation and board level assembly processes. Warpage of a package is a result of curing shrinkage of encapsulated mold compounds (EMC) and CTE mismatch between various packaging materials. In a completed package, all components are bound together by the crosslinked polymers, i.e. EMC and dieattaching adhesive (D/A). No component can expand or shrink freely. In a typical array package, warpage is in the form of either a ‘crying face (corners facing downward) or a ‘smiling face (corners facing upward), depending on the correlations of the packaging materials mechanical, physical and chemical properties. Fine pitch ball grid array (fpBGA) is a chip scale package offering a competitive solution for mobile applications. Package thickness ranges from 1.4mm down to 0.6mm with ball pitches as small as 0.4mm. Since the package is very thin, warpage control is a big challenge. In this study, an accurate finite element model, incorporated appropriate material properties was developed to predict the warpage of fpBGA under reflow condition. The experimental measurements of the warpage behavior of the fpBGA under solder-reflow condition were conducted using an Akrometrix TherMoire PS200.The experimental results were compared with the results of FE analysis, which provides feedbacks for modeling optimization. Effects of material properties and geometric parameters on thermal warpage were then studied using the optimized models.
Ke Xue Jingshen Wu Haibin Chen Jingbo Gai Angus Lam
Department of Mechanical Engineering, The Hong Kong University of Science and TechnologyClear Water Department of Aeronautics and Astronautics, Harbin Engineering University, Harbin, Heilongjiang Prov ASAT Holdings Limited, Dongguan, China
国际会议
北京
英文
317-321
2009-08-10（万方平台首次上网日期，不代表论文的发表时间）