• 마이크로전자및패키징학회지
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• 제22권2호
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• pp.61-68
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• 2015

박형 package-on-package의 상부 패키지와 하부 패키지에 대하여 에폭시 몰딩 컴파운드(EMC)에 따른 warpage 특성을 분석하였다. 또한 동일한 EMC로 몰딩한 패키지들의 warpage 편차를 측정하고 박형 상부 기판과 하부 기판 자체의 warpage 편차를 측정함으로서, 박형 패키지에서 warpage 편차를 유발하는 원인을 분석하였다. 박형 기판을 사용한 상부 및 하부 패키지에서는 기판 자체의 큰 warpage 편차에 기인하여 EMC의 물성이 패키지의 warpage에 미치는 영향을 규명하는 것이 어려웠다. EMC의 몰딩 면적이 $13mm{\times}13mm$로 기판($14mm{\times}14mm$)의 대부분을 차지하는 상부 패키지에서는 온도에 따른 warpage의 변화 거동이 유사하였다. 반면에 EMC의 몰딩 면적이 $8mm{\times}8mm$인 하부 패키지의 경우에는 (+) warpage와 (-) warpage가 한 시편에 모두 존재하는 복합적인 warpage 거동에 기인하여 동일한 EMC로 몰딩한 패키지들에서도 상이한 온도-warpage 거동이 측정되었다.

• 마이크로전자및패키징학회지
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• 제27권3호
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• pp.61-67
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• 2020

본 논문에서는 FEM(유한요소) 기법을 사용하여 칩이 실장되는 않은 substrate와 칩이 실장된 substrate의 warpage를 해석하여 칩의 실장이 warpage에 미치는 영향을 비교·분석하였다. 또한, warpage를 감소시키기 위한 substrate의 층별 두께의 영향도 분석과 층별 두께 조건을 다구찌법에 의한 신호 대 잡음 비로 분석하였다. 해석 결과에 의하면 칩이 실장되면 substrate의 warpage는 패턴의 방향이 변할 수 있고, 칩이 실장되면서 패키지의 강성도(stiffness)가 증가하고, 패키지 상·하의 열팽창계수의 차이가 작아지면서 warpage는 감소하였다. 또한, 칩이 실장되지 않은 substrate를 대상으로 설계 파라메타의 영향도 분석 결과에 의하면 warpage를 감소시키기 위해서는 회로층 중에서 내층인 Cu1과 Cu4를 중점 관리하고, 다음으로 바닥면의 solder resist 층의 두께와 Cu1과 Cu2 사이의 프리프레그 층의 두께를 관리해야 한다.

• Design & Manufacturing
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• 제2권4호
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• pp.54-61
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• 2008

Warpage, which is one of the molding trouble, acts as possible factor which results in defect in assembly. In this study, a mold was designed to produce specimens with rib parallel to flow direction, specimens with rib perpendicular to flow direction and specimens without rib. This work researched change of warpage according to injection molding condition such as injection pressure, packing pressure, packing time, resin temperature, mold temperature in non-crystalline resins(PC, ABS), crystalline resins(PP, PA66), and 30% glass fiber reinforced-resins(PC, ABS, PP, PA66).Specimens with rib and Crystalline resins show more warpage than specimens without rib and non-crystalline resins, respectively. Glass fiber reinforced-resins and specimens with rib parallel to flow direction show smaller warpage than conventional resins and specimens with rib perpendicular to flow, respectively. Specimens with rib and specimens without rib show reduced warpage as packing time increases. In addition, warpage increase as resin temperature increases. It is found that CAE shows similar tendency with experiment as packing time, resin temperature. when the rib is caused, warpage will reduce and prevent the transformation. product of a irregular form occurs warpage. In the study It'll be basic data that product occurs warpage, preferablity.

• 마이크로전자및패키징학회지
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• 제21권2호
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• pp.65-70
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• 2014

박형 package-on-package의 상부 패키지에 대하여 PCB 기판, 칩본딩 및 에폭시 몰딩과 같은 공정단계 진행에 따른 warpage 특성을 분석하였다. $100{\mu}m$ 두께의 박형 PCB 기판 자체에서 $136{\sim}214{\mu}m$ 범위의 warpage가 발생하였다. 이와 같은 PCB 기판에 $40{\mu}m$ 두께의 박형 Si 칩을 die attach film을 사용하여 실장한 시편은 PCB 기판의 warpage와 유사한 $89{\sim}194{\mu}m$의 warpage를 나타내었으나, 플립칩 공정으로 Si 칩을 PCB 기판에 실장한 시편은 PCB 기판과 큰 차이를 보이는 $-199{\sim}691{\mu}m$의 warpage를 나타내었다. 에폭시 몰딩한 패키지의 경우에는 DAF 실장한 시편은 $-79{\sim}202{\mu}m$, 플립칩 실장한 시편은 $-117{\sim}159{\mu}m$의 warpage를 나타내었다.

• 마이크로전자및패키징학회지
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• 제16권1호
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• pp.27-31
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• 2009

본 논문에서는 웨이퍼 레벨 기술을 이용한 CIS용 폴리머 접합 기술을 연구하고 접합 후의 warpage 분석과 개별 패키지의 신뢰성 테스트를 수행하였다. 균일한 접합 높이를 유지하기 위하여 glass 웨이퍼 상에 dam을 형성하고 접합용 폴리머 층을 patterning하여 Si과 glass 웨이퍼의 접합 테스트를 수행하였다. Si 웨이퍼의 접합온도, 접합 압력 그리고 접합 층이 낮을수록 warpage 결과가 감소하였으며 접합시간과 승온 시간이 짧을수록 warpage 결과가 증가하는 것을 확인하였다. 접합 된 웨이퍼를 dicing 하여 각 개별 칩 단위로 TC, HTC, Humidity soak의 신뢰성 테스트를 수행하였으며 warpage 결과가 패키지의 신뢰성 결과에 미치는 영향은 미비한 것으로 확인되었다.

• 대한기계학회논문집A
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• 제33권6호
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• pp.577-583
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• 2009

In this work, a design method that minimizes PCB warpage is proposed. This work suggests that narrow dummy patterns are placed on the discetized location along the periphery of the PCB to control the warpage. The warpage is numerically simulated base on direct modeling of PCB patterns. The optimal pattern that minimizes warpage is determined using the human-based genetic algorithm.

• 마이크로전자및패키징학회지
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• 제20권2호
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• pp.33-38
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• 2013

In this study, both a finite element analysis and an experimental analysis are executed to investigate the mechanical characteristics of dielectric material effects on warpage. Also, viscoelastic material properties are measured by DMA and are considered in warpage simulation. A finite element analysis is done by using both thermal elastic analysis and a thermo-viscoelastic analysis to predict the nonlinear effects. For experimental study, specimens warpage of non-symmetric structure with body size of $22.5{\times}22.5$ mm, $37.5{\times}37.5$ mm and $42.5{\times}42.5$ mm are measured under the reflow temperature condition. From the analysis results, experimental warpage is not similar to FEA results using thermal elastic analysis but similar to FEA results using thermo-viscoelastic analysis. Also, its effect on substrate warpage is increased as core thickness is decreased and body size is getting larger. These FEA and the experimental results show that the nonlinear characteristics of dielectric material play an important role on substrate warpage. Therefore, it is strongly recommended that non-linear behavior characteristics of a dielectric material should be considered to control warpage of FCBGA substrate under conditions of geometry, structure and manufacturing process and so on.

• 소성∙가공
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• 제15권1호
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• pp.76-81
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• 2006

In this study, warpage characteristics of mobile phone cover through injection molding process were investigated using design of experiments in injection molding process. Warpage in plastic injection molding has a significant effect on quality of product. Effects of injection time, packing pressure, packing time, mold temperature and melt temperature on the warpage of mobile phone cover were considered by numerical analysis and experiment with Taguchi method. The degree of warpage for the injection molded part was measured by using three dimensional coordinate measurement machine. It was shown that temperature control factor has more significant effect on the warpage of mobile phone cover than pressure control factor.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 금형가공,미세가공,플라스틱가공 공동 심포지엄
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• pp.126-131
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• 2005

In the present study, warpage characteristics of mobile phone cover through injection molding process were investigated by using design of experiments. Warpage in plastic injection molding process has a significant effect on quality of product. Effects of injection time, packing pressure, packing time, mold temperature ana melt temperature on warpage of mobile phone cover were considered by CAE analysis and experiment with Taguchi method. The degree of warpage for the injection molded product was measured by using three dimensional CMM. It was shown that temperature parameter has more significant effect on the warpage of mobile phone cover than pressure parameter.

• 소성∙가공
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• 제17권6호
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• pp.443-448
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• 2008

Fiber reinforced injection molded parts are widely used in recent years because of their improved properties of materials such as specific stiffness, specific strength, and specific toughness. The demand for products with high precision is increasing and it is important to minimize the warpage of the products. The warpage of short-fiber reinforced product is caused by anisotropy induced by fiber orientation as well as the residual stresses induced during the molding process. In order to reduce the warpage of the part, it is important to achieve successful mold design, processing control, and part design. In the present study, the design of gating system, molding condition, and part structure were carried out and verified with numerical analysis using a commercial CAE code Moldflow. The numbers and locations of gates were iteratively determined, and the molding conditions which can decrease the warpage of the part were investigated. Finally, slight structural modification of the part was conducted to reduce the locally concentrated warpage.