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In recent years, Package on Package (PoP) is increasingly used for high density package solutions. Generally the top package is a stacked memory packaging system connected to a bottom logic packaging system via solder joint: this is representative of PoP configurations. To guarantee the assembly yield and reliability of the solder joint between the top package and bottom package, mechanical compliance between these two packages is crucial during package stacking. Henceforth package warpage needs to be understood and controlled to meet the assembly yield targets. The complexity of the package configuration increases by thinner package thickness, higher number of stacking dies and large package size. Controlling the warpage within the target requirement is very challenging, especially when the material behaviors of substrate, die, molding compound and die attach film are different and also changing as a function of temperature. Certainly, the material properties of key components in top PoP package plays a crucial role in warpage performance. Among various material properties, the chemical cure shrinkage, coefficient of thermal expansion and storage modulus for the molding compounds are determining factors on the temperature dependant warpage control of top PoP package. Warpage variation still exists within parts processed at the same time mainly due to slight material property variation. In this paper, the cause of the warpage variation is investigated. The main cause was found to be filler migration effect in narrow gaps with in the stacked die package during the mold process, which resulted in different filler concentration and distribution, and finally different local molding compound material property among the package unit location in the substrate strip. The findings indicate that mold pressure is not a major modulator of warpage, while filler distribution can dramatically alter the warpage behavior. FEA model results and warpage data are presented to validate the filler migration phenomena and warpage behavior impact. The findings and results provide some clues and design/process guideline for warpage control in Top PoP package, which influence the PoP assembly yield and reliability.

A efficient method of entering the state is the Friction stir welding (FSW).The joining temperature is lower than that and the phase used Inside the types of Welding via selection. With this one way, FSW is deemed to have give over combination welding, a few focal points for separate metal with welding. This research focuses on the impacts of material location and rotational speed on tensile strength. This study focuses on the latest test of the unit. For the welding process, material alloys for AA2014 and AA7075 are selected. The welded ones aluminium compounds are materials6.0 mm thick and are not used by conventional manufacturing equipment. Three sets of Varying rotational speeds have created joints of the system and by replacing the fixed situation on advancement and progress with drawing sides of the material. The study found that If AA7075aluminium amalgams with clear surface appearance and no surface appearance were set at a rotational speed of 1000 rpm on the propelling side. internal deformity over welding region, the greatest rigidity of 207 MPa has been achieved sample for sample C, while the most reduced elasticity was 160 MPa when it was AA7075,mounted on the retreating side with extreme passage deserts in the welding field contributing spread to be divided, it was obtained for sample A. Along these lines, more fragile materials should on the propelling hand, set it in specific welding to cause warmth from the revolution of the instrument and smoothness of the arrangement of the stream of content in the mixed region.