• Title/Summary/Keyword: CTE

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Measurement of EMC/PCB Interfacial Adhesion Energy of Chip Package Considering Warpage (휨을 고려한 칩 패키지의 EMC/PCB 계면 접합 에너지 측정)

  • Kim, Hyeong Jun;Ahn, Kwang Ho;Oh, Seung Jin;Kim, Do Han;Kim, Jae Sung;Kim, Eun Sook;Kim, Taek-Soo
    • Journal of the Microelectronics and Packaging Society
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    • v.26 no.4
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    • pp.101-105
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    • 2019
  • The adhesion reliability of the epoxy molding compound (EMC) and the printed circuit board (PCB) interface is critical to the quality and lifetime of the chip package since the EMC protects PCB from the external environment during the manufacturing, storage, and shipping processes. It is necessary to measure adhesion energy accurately to ensure product reliability by optimizing the manufacturing process during the development phase. This research deals with the measurement of EMC/PCB interfacial adhesion energy of chip package that has warpage induced by the coefficient of thermal expansion (CTE) mismatch. The double cantilever beam (DCB) test was conducted to measure adhesion energy, and the spring back force of specimens with warpage was compensated to calculate adhesion energy since the DCB test requires flat substrates. The result was verified by comparing the adhesion energy of flat chip packages come from the same manufacturing process.

Numerical Analysis of Warpage and Stress for 4-layer Stacked FBGA Package (4개의 칩이 적층된 FBGA 패키지의 휨 현상 및 응력 특성에 관한 연구)

  • Kim, Kyoung-Ho;Lee, Hyouk;Jeong, Jin-Wook;Kim, Ju-Hyung;Choa, Sung-Hoon
    • Journal of the Microelectronics and Packaging Society
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    • v.19 no.2
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    • pp.7-15
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    • 2012
  • Semiconductor packages are increasingly moving toward miniaturization, lighter and multi-functions for mobile application, which requires highly integrated multi-stack package. To meet the industrial demand, the package and silicon chip become thinner, and ultra-thin packages will show serious reliability problems such as warpage, crack and other failures. These problems are mainly caused by the mismatch of various package materials and geometric dimensions. In this study we perform the numerical analysis of the warpage deformation and thermal stress of 4-layer stacked FBGA package after EMC molding and reflow process, respectively. After EMC molding and reflow process, the package exhibits the different warpage characteristics due to the temperature-dependent material properties. Key material properties which affect the warpage of package are investigated such as the elastic moduli and CTEs of EMC and PCB. It is found that CTE of EMC material is the dominant factor which controls the warpage. The results of RSM optimization of the material properties demonstrate that warpage can be reduced by $28{\mu}m$. As the silicon die becomes thinner, the maximum stress of each die is increased. In particular, the stress of the top die is substantially increased at the outer edge of the die. This stress concentration will lead to the failure of the package. Therefore, proper selection of package material and structural design are essential for the ultra-thin die packages.

Cyclic Oxidation Behavior of Vacuum Plasma Sprayed NiCoCrAlY Overlay Coatings (진공 플라즈마 용사법을 통해 형성된 NiCoCrAlY 오버레이 코팅의 반복 산화 거동)

  • Yoo, Yeon Woo;Nam, Uk Hee;Park, Hunkwan;Park, Youngjin;Lee, Sunghun;Byon, Eungsun
    • Journal of the Korean institute of surface engineering
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    • v.52 no.6
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    • pp.283-288
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    • 2019
  • MCrAlY overaly coatings are used as oxidation barrier coatings to prevent degradation of the underlying substrate in high temperature and oxidizing environment of the hot section of gas turbines. Therefore, oxidation resistance in high temperature is important property of MCrAlY coatings. Also, coefficients of thermal expansion (CTE) of MCrAlY have middle value of that of Ni-based superalloys and oxides, which have the effect of preventing the delamination of the surface oxides. Cyclic oxidation test is one of the most useful methods for evaluating the high temperature durability of coatings used in gas turbines. In this study, NiCoCrAlY overlay coatings were formed on Inconel 792(IN 792) substrates by vacuum plasma spraying process. Vacuum plasma sprayed NiCoCrAlY coatings and IN 792 susbstrates were exposed to 1000℃ one-hour cyclic oxidation environment. NiCoCrAlY coatings showed lower weight gain in short-term oxidation. In long-term oxidation, IN 792 substrates showed higher weight loss due to delamination of surface oxide but NiCoCrAlY coatings showed lower weight loss. X-ray diffraction (XRD) analysis showed α-Al2O3 and NiCr2O4 was formed during the cyclic oxidation test. Through cross-section observation using scanning electron microscopy (SEM) and electron back scatter diffraction (EBSD) analysis, thermally grown oxide (TGO) layer composed of α-Al2O3 and NiCr2O4 was formed and the thickness of TGO increased during 1000℃ cyclic oxidation test. β phase in upper side of NiCoCrAlY coating was depleted due to oxidation of Al and outer beta depletion zone thickness also increased as the cyclic oxidation time increased.

Synthesis and Characterization of Heat Resistant Organophilic Layered Silicate Modified with Oligo(amic acid)s Having Alkyl Side Chains and Their Nanocomposites (알킬기가 도입된 올리고 아믹산 구조를 가진 고내열 친유기 층상 실리케이트의 제조 및 이를 이용한 나노복합재의 특성평가)

  • Han Ji Yun;Won Jong Chan;Lee Jae Heung;Suh Kyung-Do;Kim Yong Seok
    • Polymer(Korea)
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    • v.29 no.5
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    • pp.451-456
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    • 2005
  • In the field of designing of nano-fillers of polyimide nanocomposites, the two strategic points are the heat-resistance and compatibility with polyimide, a matrix polymer. In this study, we designed oligo(amic acid) having alkyl side chains and terminal amine groups to satisfy previous requirements and studied the modification of surface of layered silicates. Oligo(amic acid)s were prepared by the reaction of diamine monomers and PMDA and their molecular weight was controlled in about 2000g/mol. After that, acidification and ion exchange reaction led to the high-temperature organophilic layered silicate (OLS). XRD pauerns of OLS showed the more increased gallery spacing by $4{\AA}$ than that of the pristine layered silicate and the initial decomposition temperatures of OLS were in above $280^{\circ}C$. The polyimide nanocomposite films based on heat resistant OLS showed that the OLSs were well dispersed through the matrix and their CTEs showed a decrease of $26\%$ compared with pristine polyimide films.

Applicability Assessment of Epoxy Resin Reinforced Glass Fiber Composites Through Mechanical Properties in Cryogenic Environment for LNG CCS (에폭시 수지가 적용된 유리섬유 복합재료의 극저온 환경 기계적 특성 분석을 통한 LNG CCS 적용성 평가)

  • Yeom, Dong-Ju;Bang, Seoung-Gil;Jeong, Yeon-Jae;Kim, Hee-Tae;Park, Seong-Bo;Kim, Yong-Tai;Oh, Hoon-Gyu;Lee, Jae-Myung
    • Journal of the Society of Naval Architects of Korea
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    • v.58 no.4
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    • pp.262-270
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    • 2021
  • Consumption of Liquefied Natural Gas (LNG) has increased due to environmental pollution; therefore, the need for LNG carriers can efficiently transport large quantities of LNG, is increased. In various types of LNG Cargo Containment System (CCS), Membrane-type MARK-III composed of composite materials is generally employed in the construction of an LNG carrier. Among composite materials in a Mark-III system, glass-fiber composites act as a secondary barrier to prevent the inner hull structure from leakage of LNG when the primary barrier is damaged. Nevertheless, several cases of damage to the secondary barriers have been reported and if damage occurs, LNG can flow into the inner hull structure, causing a brittle fracture. To prevent those problems, this study conducted the applicability assessment of composite material manufactured by bonding glass-fiber and aluminum with epoxy resin and increasing layer from three-ply (triplex) to five-ply (pentaplex). Tensile tests were performed in five temperature points (25, -20, -70, -120, and -170℃) considering temperature gradient in CCS. Scanning Electron Microscopy (SEM) and Coefficient of Thermal Expansion (CTE) analyses were carried out to evaluate the microstructure and thermos-mechanical properties of the pentaplex. The results showed epoxy resin and increasing layer number contributed to improving the mechanical properties over the whole temperature range.

Effect of Amino Modified Siloxanes with Two Different Molecular Weights on the Properties of Epoxy Composites for Adhesives for Micro Electronics (전자소재 접착제용 에폭시에 두 종의 다른 당량수를 갖는 아미노 변성 실록산이 미치는 영향)

  • Yu, Kihwan;Kim, Daeheum
    • Applied Chemistry for Engineering
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    • v.22 no.1
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    • pp.104-108
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    • 2011
  • In the non-conductive adhesives (NCAs) for adhesion of micro electro mechanical system (MEMS), there are some problems such as delamination and cracking resulting from the large differences of coefficients of thermal expansion (CTE) between NCAs and substrates. So, the addition of inorganic particles such as silica and nano clay to the CTEs composit have been applied to reduce the CTEs of the adhesives. Additions of the flexibilizers such as siloxanes have also been performed to improve the flexibility of epoxy composite. Amino modified siloxane (AMSs) were used to improve compatibility between epoxy and siloxane. In this study, glass transition temperatures (Tg) and moduli of those composites were measured to confirm the effects of AMS with two different equivalents on thermal/mechanical properties of AMS/epoxy composites. Tg of KF-8010/epoxy composites decreased from 148 to $122^{\circ}C$ and those of X-22-161A/epoxy composites decreased from 148 to $121^{\circ}C$. Moduli of KF-8010/epoxy composites decreased from 2648 to 2143 MPa by adding KF-8010 and moduli of X-22-161A/epoxy composites decreased from 2648 to 2014 MPa. In short, using long Si-O chain AMS leads to a greater decrease in moduli. However, haven't showed significant differences in Tg's.

Antioxidant Activities of Various Black Soybean Tissues (Glycine max L.) Harvested from Different Cultivation Regions (재배지역에 따른 검정콩 부위별 추출물의 항산화 활성)

  • Kim, Hyun Young;Wo, So-Yeun;Yang, Ji Yeong;Song, Seung-Yeob;Seo, Woo Duck;Lee, Mi Ja;Choi, Man-Soo
    • The Korean Journal of Food And Nutrition
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    • v.34 no.4
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    • pp.331-339
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    • 2021
  • With the aim of developing region specialized crops, this study was conducted to clarify effects of variant and cultivation region on antioxidative activities in various black soybean (Glycine max L.) seed tissues. Three black soybean varieties (SCEL-1, Wonheug, and Cheongja 3) were each cultivated in 4 different regions (Jeonju, Pyeongchang, Paju, and Cheonan). Harvested seeds were used to assess DPPH and ABTS radical scavenging activity, and total polyphenol, flavonoid and anthocyanin content. SCEL-1 soybean hull contained higher DPPH and ABTS radical scavenging activity (61% and 85% respectively) compared to Wonheug (40% and 50% respectively). SCEL-1 cultivated in Pyeongchang displayed the highest total polyphenol and flavonoid content (1,189 mg GAE/100g sample and 951 mg CTE/ 100g sample, respectively). Total anthocyanin content was ranked in the following order: SCEL-1>Wonheug>Cheongja 3. All black soybeans showed much higher antioxidant activity in the soybean hull than in the dehulled soybean. The antioxidant activity of black soybeans cultivated at high latitudes was high. These results suggest that the best black soybean variant for high beneficial biological activities is the SCEL-1 variant. For a complete understanding of the potential of black soybean as functional foods, we plan to further analyze their antioxidant activities in future studies.

A Study on the Method of Evaluating Optical-system Performance and an Athermal Structure through Thermal Analysis of the Korsch Telescope (Korsch 망원경의 열분석을 통한 광학계 성능 평가 방법 및 비열화 구조 연구)

  • Kim, Kyu-Ho;Park, Seong-Woo;Park, Seung-Han;Lee, Kyoung-Mook;Jung, Mee-Suk
    • Korean Journal of Optics and Photonics
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    • v.32 no.6
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    • pp.266-275
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    • 2021
  • In this paper, a method for evaluating optical-system performance and an athermal structure through thermal analysis of the Korsch telescope was studied. In the case of an optical system having a complex asymmetrical structure, there is a limit to implementing the satellite structure by applying the coefficient of thermal expansion (CTE) in the optical-design software, so it is difficult to evaluate the performance of the optical system against temperature changes. To solve this problem, using mechanical design software all length changes were implemented in all structures that affect the optical system according to temperature, and the value of the change in distance between optical components due to temperature change was organized. Also, the values of changes in shape and thickness of the optical components against temperature changes are organized in the optical-design software. All changes derived from both software packages were applied in the optical software to evaluate the performance of the optical system. As a result, it was found that the MTF for a spatial resolution of 71.4 cycles/mm was maintained at more than 25% in the range from 9 ℃ to 33 ℃. In addition, the performance of the optical system applying the improved structure was evaluated, by finding the structure that had the most influence on the optical system's performance change, and deriving an athermal structure to reduce the effect. As a result, it was found that the MTF for a resolution of 71.4 cycles/mm was maintained at over 67% in the range from 9 ℃ to 33 ℃.

Serobiological Characteristics and Antibiotic Sensitivity of Pseudomonas spp. Isolated from Spring Waters in Seoul Area (서울근교 약수터에서 분리한 Pseudomonas속균의 혈청생화학적 특성 및 항균제 감수성)

  • Park, Seog-Gee;Kim, Moo-Sang;Ham, Hee-Jin;Kim, Eun-Jung;Hwang, Kwan-Ho
    • Journal of Food Hygiene and Safety
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    • v.13 no.3
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    • pp.305-312
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    • 1998
  • In order to investigate the species, serobiological characteristics and antibiotic sensitivity of Pseudomonas spp, we isolated Pseudomonas spp from 57 spring waters around Seoul area for spring, summer and autumn and identified Pseudomonas spp by biochemical characteristics and serological method. And also we tested the antibiotic sensitivity test by discdiffusion method. Of 57 spring waters tested, Pseudomonas spp were isolated from 33 spring waters(57.9%). Isolation rate of Pseudomonas spp in spring season was 28.1%, summer 21.1% and autumn 28.1%. Only 1 spring water was detected Pseudomonas spp in all seasons and 9 (15.8%) were detected for 2 seasons and 13 (22.8%) were for only 1 season. Isolation rate of Pseudomonas spp at Mt. Cheonggye was 50% and followed by Mt. Bookhan 35.7%, Mt. Daemo 33.3%, Mt. Dobong 29.6%, Mt. Surak 25.9%, Mt. Woomyun 22.2% and Mt. Bulam 7.4%. Of 44 Pseudomonas spp, 22 strains (50%) were identified by Ps. putida, Ps. aeruginosa, Ps. fluorescens and Ps. mendocina were identified 6 strains (13.6%), respectively. 4 strains (9.1%) were identified by Ps. aureofaciens. Of 6 Ps. aeruginosa, serotype A was 2 strains, B, E, G, and K was 1 strain, respectively. Of 44 Pseudomonas spp, resistance rate to amoxicillin was 90.9% and followed by chloramphenicol 84.1%, tetracycline 84.1%, carbenicillin 81.8%, nalidixic acid 68.2%, neomycin 38.6%, streptomycin 31.8%, gentamicin 4.6%, kanamycin 4.6% and colistin 2.3%. Ps. aeruginosa was more sensitive to carbenicillin than other Pseudomonas spp isolated from spring waters in Seoul area but more resistant to kanamycin, and Ps. aureofaciens was no resistant to streptomycin. Among multiple drug resistance, resistance to 5 drugs was 31.8%, 4 drugs 15.9%, 7 drugs 13.6%, 1 drug and 2 drugs 4.6%, and 8 drugs 2.3%, respectively. The multiple resistance patterns detected highestly were NA-CB-C-TE-AMC (18.2%), NA-CB-N-C-TE-AMC (13.6%), CBC-TE-AMC (11.4%) and NA-CB-N-C-TE-AMC-S (9.1%).

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