| Fan-out panel level packaging(FOPLP)is one of the advanced packaging methods of microelectronics today.It has attracted a lot of attention by relying on the advantages of low cost and high integration,and it can meet the application of high integration,miniaturization and other requirements.However,due to the mismatch of the coefficient of thermal expansion(C TE)of the packaging material and the curing shrinkage of the molding compound,it is easy to warp and crack during the entire process.How to achieve FOPLP low warpage and how to predict and improve warpage has become a research hotspot.At present,the research on the warpage problem mainly uses the finite element method to analyze a certain process,a certain material or a certain structure,and explain the difference between the finite element method and the actual results,but does not explore the influence mechanism of the package structure and the material parameters on the warpage,and the warpage prediction and improvement.This paper proposes a new method to study the warpage of FOPLP based on the C hip First process.This method establishes a finite element simulation model to predict and improve the warpage of different package structures and material parameters,explore the influence mecha nism of package structure and material parameters on warpage,and achieve the purpose of FOPLP low warpage.The research content of this paper is as follows:(1)In view of the structure and constraints of FOPLP post-cured,the parameterized simulation command flow is used for finite element analysis,and the parameterized simulation command flow is continuously optimized.The parameterized simulation command flow is used to analyze the situation without and with chip respectively to realize the warpage simulation of different material parameters and package structures.(2)Investigate the effect of warpage in the post-curing stage of chipless FOPLP.Based on the finite element simulation model,the relationship between the thickness of carrier and material parameters,the thickness of EMC and material parameters,the hole/groove structure and the warpage are explained.The thickness of carrier is increased,the rigidity of the package is increased,the warpage decreases by 24.2% and the downward trend slows down.The Young's modulus of carrier increases,which increases the rigidity of the package,at the same time,changing the C TE of carrier reduces the warpage by 47.1%.The warpage decreased by 47.6% when the thickness of EMC decreased,and the warpage decreased by81.7% when the material parameters of EMC changed.For EMC,lower Young's modulus combined with better matching C TE results in lower internal stress and lower warping.Limited by the number and size of holes/grooves,both have little effect on warpage,the material parameters of EMC have a significant influence on the warpage.(3)Investigate the effect of warpage in the post-curing stage of 5×5 mm chip FOPLP.Based on the finite element simulation model,the relationship between the thickness of carrier and material parameters,the thickness of EMC and material parameters,the thickness of chip,the groove structure,the packaging density and the warpage are explained.The thickness of carrier is increased,the rigidity of the package increases,and the warpa ge decreases by 24.2% and the downward trend first increases and then slows down.The Young's modulus of carrier increases,which increases the rigidity of the package,at the same time,changing the C TE of carrier reduces the warpage by 60.8%.The thickness of EMC is reduced,and the warpage is reduced by 14.4%,and the material parameters of EMC changed,and the warpage is reduced by 84.2%.When the C TE of EMC is less than the C TE of carrier,the upward convex(crying face)negative warping behavior will occur.The groove structure,chip thickness and packaging density are limited by the number and size of grooves and chips,increasing them will reduce warpage but the effect is modest,the material parameters of carrier and EMC have a significant influence on the warpage. |
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