• Journal of the Semiconductor & Display Technology
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• v.17 no.4
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• pp.42-45
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• 2018

As The semiconductor decrease from 10 nanometer to 7 nanometer, It is suggested that "More than Moore" is needed to follow Moore's Law, which has been a guide for the semiconductor industry. Fan-Out Wafer Level Package(FOWLP) is considered as the key to "More than Moore" to lead the next generation in semiconductors, and the reasons are as follows. the fan-out WLP does not require a substrate, unlike conventional wire bonding and flip-chip bonding packages. As a result, the thickness of the package reduces, and the interconnection becomes shorter. It is easy to increase the number of I / Os and apply it to the multi-layered 3D package. However, FOWLP has many issues that need to be resolved in order for mass production to become feasible. One of the most critical problem is the warpage problem in a process. Due to the nature of the FOWLP structure, the RDL is wired to multiple layers. The warpage problem arises when a new RDL layer is created. It occurs because the solder ball reflow process is exposed to high temperatures for long periods of time, which may cause cracks inside the package. For this reason, we have studied warpage in the FOWLP structure using commercial simulation software through the implementation of the reflow process. Simulation was performed to reproduce the experiment of products of molding compound company. Young's modulus and poisson's ratio were found to be influenced by the order of influence of the factors affecting the distortion. We confirmed that the lower young's modulus and poisson's ratio, the lower warpage.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.1
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• pp.75-81
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• 2015

In this paper, numerical analysis by finite element method and parameter design by the Taguchi method were used to reduce warpage of a two passive components embedded double side substrate for PoP(Package on Package). The effect of thickness of circuit layers (L1, L2) and thickness of solder resist (SR_top, SR_BTM) were analyzed with 4 variations and 3 levels(minimum, average and maximum thickness) to find optimized thickness conditions. Also, paste effect of solder resist on unit area of top surface was analyzed. Finally, experiments was carried out to prove numerical analysis and the Taguchi method. Based on the numerical and experimental results, it was known that circuit layer in ball side of substrate was the most severe determining deviation for reducing warpage. Buried circuit layer in chip side, solder resist and were insignificant effects on warpage relatively. However, warpage decreased as circuit layer in ball side thickness increased but effect of solder resist and circuit layer in chip side thickness were conversely.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.1
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• pp.17-22
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• 2018

In this paper, the effects of solder joint aging on the reliability of embedded package solder joints were investigated using numerical analysis by finite element method. Solder joints were SAC305 with aging time 0, 60, 180 days. For reliability analysis, warpage of package and equivalent creep strain (ECS) and total strain energy density (TSED) of solder joint were analyzed. The analysis results show that the package warpage is decreased in the case of the embedded package compared to the non embedded package, and the reliability life of the solder joint is predicted to be high. Also, it was interpreted that the longer the aging time, the less the warpage of the embedded package, but the reliability life of the solder joint would be shortened.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.5
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• pp.1119-1124
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• 2008

This study presents the preform injection molding and the blow molding of the injection stretch-blow molding process for PET bottles. The numerical analysis of the injection molding and the blow molding of a preform is considered in this paper using CAE with a view to minimize the warpage and the thickness. In order to determine the design parameters and processing conditions in injection/blow molding, it is very important to establish the numerical model with physical phenomenon. In this study, a three dimensional model has been introduced for the purpose and flow simulations of filling, post-filling and cooling process are carried out. The simulations resulted in the warpage in good agreement with the measurements. Also, from the result of numerical analysis, we appropriately predicted the warpage, deformation and thickness distribution along the product walls.

• Design & Manufacturing
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• v.9 no.3
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• pp.9-13
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• 2015

Plastic material has been applied to many automobile parts with the automotive lightweighting trend. In this study, a passenger air bag(PAB) housing which is produced by steel material in the present were molded using a plastics material. Before design and making of a mold for the PAB housing molding, it was carried out injection molding analysis. By analyzing the deformation results, the correction dimension for mold designing was determined. The design and manufacturing the mold applied the correction dimension were conducted. It was performed actual injection molding. The warpage value of the PAB housing was similar to the warpage of the injection molding analysis.

• Journal of the Korean Society of Industry Convergence
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• v.14 no.3
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• pp.87-93
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• 2011

When applying back panel(this material is aluminum complex panel coated with fire resistance substances) for curtain wall, solar radiation and heat storage of indoor air occurs to result in thermal warpage for back panel. The purpose of this analysis is to find out the cause of thermal warpage and come up with a solution to prevent changes of back panel and reduce elements that bring negative visual elements. Also to solve this problem analyse that case to reduce heat transfer by inserting additional material and cases to increase air space distance.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.5
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• pp.44-52
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• 1996

A procedure predicting warpage and post-deformation due to heat resistance test is presented. The procedure is applied to the injection molding processes of automotive plastic components, which are the door trim and the instrument pannel. The warpage of products is obtained from the residual stress after filling, packing and cooling process, and the post deformation due to the heat resistance test is calculated in the structural analysis of the product at the ejection temperature with the initial condition of residual stress, the boundary conditions and heat resistance conditions. The analyses give some useful guide lines in the design of automotive plastic parts which should satisfy heat resistance regulation.

• Transactions of Materials Processing
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• v.14 no.3 s.75
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• pp.269-276
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• 2005

The purpose of this research is the warpage reduction for intake-manifold which is made to the injection molding. Intake-manifold is assembling to ultra sonic welding after forming. Therefore deformation is influence on the performance and manufacture to intake-manifold product. Location and number of gates, filling time, mold temperature, packing time, packing pressure and cooling time are factors that affect the deformation of injection molding product. Therefore, the injection molding characteristics of intake-manifold and the estimated deformation are detected by CAE analysis and compare measuring data in this study.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.8
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• pp.824-833
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• 2012

The shrinkage and the warpage of the moulded part are influenced by the design of the product and injection mould. In a flat part with a partly thick volume, the warpage of the flat part is created from the difference of the shrinkage between thin and thick regions. The warpage of the flat part with a partly thick volume can be reduced by a proper design of the cooling system in the injection mould. The goal of this paper is to design properly cooling channels of injection mould to manufacture a flat part with a partly thick volume. The conformal cooling channel is adopted to improve cooling characteristics of a region with the thick volume. The linear cooling channels are assigned to the other region. The proper design of the conformal cooling channels is obtained from three-dimensional injection molding analysis for various design alternatives. The moulding characteristics of the designed mould with both conformal and linear cooling channels are compared to those of the mould with linear cooling channels from viewpoints of temperature, shrinkage and warpage of the moulded part using numerical analysis. Injection mould with both conformal and linear cooling channels for the flat part with a partially thick volume is fabricated. In addition, injection moulding experiments are performed using the fabricated mould. From the results of the injection moulding experiments, it has been shown that the designed mould can successfully fabricate the flat part with a partially thick volume.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6464-6471
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• 2014

The UV curing method is a popular process for lens molding on a unit wafer. This process, however, has several drawbacks including wafer adhesion during the ejection process after curing, errors in lens shape and wafer warpage due to material shrinkage during the curing process, and lens centering errors on both sides of a wafer. Among these, the lens shape error and warpage are influenced directly by the UV curing process due to factors including the UV radiation uniformity, the degree of cure according to UV intensity, and the shrinkage characteristics of the material. Therefore, a theory is needed not only to understand the change in the material characteristics, such as the shrinkage rate due to the curing reaction, but also to establish a model. In addition, an analysis system is needed to realize the model. This study proposes a new analysis method for the wafer lens molding process by Comsol modeling. This method was verified by comparing the results with those of the actual process.