• 한국재료학회지
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• 제34권3호
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• pp.125-137
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• 2024

Composite laminates are used in a wide range of applications including defense, automotive, aviation and aerospace, marine, wind energy, and recreational sporting goods. These composite beams still exhibit problems such as buckling, local deformations, and interlaminar delamination. To overcome these drawbacks, a novel viscoelastic autoclave bonding with tapered epoxy reinforcement polyurethane films is proposed. In existing laminates, compression face wrinkling and interlaminar delamination is caused in the sandwich beam. The unique viscoelastic autoclave spunbond interlayer bonding is designed to prevent face wrinkling and absorb and distribute stresses induced by external loads, thereby eliminating interlaminar delamination in the sandwich beam. Also, the existing special reinforcement causes stress concentrations, and the core is not effectively connected, which directly affects the stiffness of the beam. To address this, a novel tapered epoxy polyurethane reinforcement adhesive film is proposed, whose reinforcement thickness gradually tapers as it enters the core material. This minimizes stress concentrations at the interface, preventing excessive adhesive squeeze-out during the bonding process, and improves the stiffness of the beam. Results indicate the proposed model avoids the formation of micro cracks, interlaminar delamination, buckling, and local deformations, and effectively improves the stiffness of the beam.

• 한국재료학회지
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• 제22권9호
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• pp.454-458
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• 2012

Various adhesive materials are used in flip chip packaging for electrical interconnection and structural reinforcement. In cases of COF(chip on film) packages, low temperature bonding adhesive is currently needed for the utilization of low thermal resistance substrate films, such as PEN(polyethylene naphthalate) and PET(polyethylene terephthalate). In this study, the effects of anhydride and dihydrazide hardeners on the low-temperature snap cure behavior of epoxy based non-conductive pastes(NCPs) were investigated to reduce flip chip bonding temperature. Dynamic DSC(differential scanning calorimetry) and isothermal DEA(dielectric analysis) results showed that the curing rate of MHHPA(hexahydro-4-methylphthalic anhydride) at $160^{\circ}C$ was faster than that of ADH(adipic dihydrazide) when considering the onset and peak curing temperatures. In a die shear test performed after flip chip bonding, however, ADH-containing formulations indicated faster trends in reaching saturated bond strength values due to the post curing effect. More enhanced HAST(highly accelerated stress test) reliability could be achieved in an assembly having a higher initial bond strength and, thus, MHHPA is considered to be a more effective hardener than ADH for low temperature snap cure NCPs.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2010년도 춘계학술발표대회 초록집
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• pp.74-74
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• 2010

모바일 정보통신기기를 중심으로 전자패키지의 초소형화, 고집적화를 위해 플립칩 공법의 적용이 증가되고 있는 추세이다. 플립칩 패키징 접합소재로는 솔더, ICA(Isotropic Conductive Adhesive), ACA(Anisotropic Conductive Adhesive), NCA(Non Conductive Adhesive) 등과 같은 다양한 접합소재가 사용되고 있다. 최근에는 언더필을 사용하는 플립칩 공법보다 미세피치 대응성을 위해 NCP를 이용한 플립칩 공법에 대한 요구가 증가되고 있는데, NCP의 상용화를 위해서는 공정성과 함께 신뢰성 확보가 필요하다. 본 연구에서는 LDI(LCD drive IC) 모듈을 위한 COF(Chip-on-Film) 플립칩 패키징용 NCP 포뮬레이션을 개발하고 이를 적용한 COF 패키지의 신뢰성을 조사하였다. 테스트베드는 면적 $1.2{\times}0.9mm$, 두께 $470{\mu}m$, 접속피치 $25{\mu}m$의 Au범프가 형성된 플리칩 실리콘다이와 접속패드가 Sn으로 finish된 폴리이미드 재질의 flexible 기판을 사용하였다. NCP는 에폭시 레진과 산무수물계 경화제, 이미다졸계 촉매제를 사용하여 다양하게 포뮬레이션을 하였다. DSC(Differential Scanning Calorimeter), TGA(Thermogravimetric Analysis), DEA(Dielectric Analysis) 등의 열분석장비를 이용하여 NCP의 물성과 경화거동을 확인하였으며, 본딩 후에는 보이드를 평가하고 Peel 강도를 측정하였다. 최적의 공정으로 제작된 COF 패키지에 대한 HTS (High Temperature Stress), TC (Thermal Cycling), PCT (Pressure Cooker Test)등의 신뢰성 시험을 수행한 결과 양산 적용 가능 수준의 신뢰성을 갖는 것을 확인할 수 있었다.

• 한국항공우주학회지
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• 제35권3호
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• pp.204-211
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• 2007

연구에서는 5가지의 접착길이를 갖는 탄소 복합재-알루미늄 단일겹침 체결부에 대한 실험을 통해 단일겹침 접착 체결부의 파손양상 및 강도를 연구하였다. 시편은 필름 형태의 접착제인 FM73m을 사용하여 이차접착으로 제작하였다. 실험 결과, 이종재료 접착 체결부의 강도는 금속-금속 체결부의 강도보다는 낮고, 복합재-복합재 체결부의 강도보다는 높게 나타났다. 접착길이 대 폭의 비가 1보다 작은 경우, 접착길이의 증가가 강도 저하에 미치는 영향이 컸지만, 접착길이 대 폭의 비가 커질수록 접착길이의 효과는 줄어드는 것으로 나타났다. 모든 시편은 최종적으로 층간분리의 형태로 파손되었다. 따라서 고강도 접착제를 사용한 체결부의 강도향상을 위해서는 적층판의 층간분리 파손을 지연시킬 수 있는 설계가 중요할 것으로 판단된다.

• Macromolecular Research
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• 제13권5호
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• pp.446-452
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• 2005

The interactions between the surface of scaffolds and specific cells play an important role in tissue engineering applications. Some cell adhesive ligand peptides including Arg-Gly-Asp (RGD) have been grafted into polymeric scaffolds to improve specific cell attachment. In order to make cell adhesive scaffolds for tissue regeneration, biodegradable nonporous poly(L-lactic acid) (PLLA) films were prepared by using a solvent casting technique with chloroform. The hydrophobic PLLA films were surface-modified by Argon plasma treatment and in situ direct acrylic acid (AA) grafting to get hydrophilic PLLA-g-PAA. The obtained carboxylic groups of PLLA-g-PAA were coupled with the amine groups of Gly-Arg-Asp-Gly (GRDG, control) and GRGD as a ligand peptide to get PLLA-g-GRDG and PLLA-g-GRGD, respectively. The surface properties of the modified PLLA films were examined by various surface analyses. The surface structures of the PLLA films were confirmed by ATR-FTIR and ESCA, whereas the immobilized amounts of the ligand peptides were 138-145 pmol/$cm^2$. The PLLA surfaces were more hydrophilic after AA and/or RGD grafting but their surface morphologies showed still relatively smoothness. Fibroblast adhesion to the PLLA surfaces was improved in the order of PLLA control

• 폴리머
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• 제33권6호
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• pp.525-529
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• 2009

우수한 성능의 2층 연성동박적층판(이하 FCCL)을 제조하기 위해서는 동박과 폴리이미드 사이에서 높은 접착력이 요구된다. 이를 위해 이종 재료로 인한 두 계면 사이의 접착력을 향상시키기 위해서는 일반적으로 기능성 실란커플링제가 사용된다. 본 연구에서는 압연동박과 폴리이미드 사이의 접착력 향상과 이미드화를 위한 고온의 열처리 조건에서도 안정한 새로운 형태의 실란커플링제를 합성하였다. 또한, 합성된 실란커플링제를 압연동박에 처리하였을 때, 표면처리제의 농도에 따른 표면변화를 관찰하였으며, 이로 인해 발생되는 접착력 변화를 확인하기 위해서 2층 FCCL을 제조하여 $90^{\circ}$ peel test를 통해 관찰하였다. 그리고, 두 종류의 폴리이미드를 이용한 FCCL에서 실란 커플링제가 접착력에 미치는 영향을 확인하였다.

• Composites Research
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• 제20권6호
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• pp.8-14
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• 2007

스킨-보강재 시편 시험을 통해 스킨과 보강재의 분리 파손 특성을 살펴보고 접합방법, 보강재 단면 및 이차 접합 파라미터의 영향을 조사하였다. 본 시험 결과와 이전 시험[1]의 결과를 종합해 볼 때, 보강패널의 스킨-보강재 분리 파손 강도를 판단하는 기준으로 스킨-보강재 시편의 파손 변위를 이용하는 것이 타당하며 동일한 접합 방법을 사용할 경우, closed형 보다 open형 보강재를 사용하는 것이 복합재 보강 패널에서 스킨과 보강재의 분리파손을 방지하는데 유리함을 알 수 있었다. 접합방법으로는 이차접합 및 접착제를 사용한 동시성형이 좋은 파손 강도를 보였으며 접착제 없는 동시성형이 가장 나쁜 파손 강도를 나타내었다. 파손 모드는 이차접합 시편은 주로 계면 파손이 발생하였으며 동시성형 시편은 복합재료의 층간분리 파손이 발생하였다. 이차 접합 시편에서는 접착제 두께가 작을수록 높은 파손 강도를 보였다. Fillet은 시편의 강도에 영향을 미치지 않았다. 표면 조도의 영향은 open형 및 closed형 시편이 다르게 나타났다.

• 대한치과보철학회지
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• 제17권1호
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• pp.23-34
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• 1979

In this study, the adhesive strength of three commercial polycarboxylate cements to ten types of dental casting alloys, such as gold, palladium, silver, indium, copper, nickel, chromium, and human enamel and dentine were measured and compared with that of a conventional zinc phosphate cement. The $8.0mm{\times}3.0mm$ cylindrical alloy specimens were made by casting. The enamel specimens were prepared from the labial surface of human upper incisor, and the dentine specimens were prepared from the occulusal surface of the human molar respectively. Sound extracted human teeth, which had been kept in a fresh condition since, extraction, were mounted in a wax box with a cold-curing acrylic resin to expose the flattened area. The mounted teeth were then placed in a Specimen Cutter (Technicut) and were cut down under a water spray, and then the flat area on the all specimens were ground by hand with 400 and 600 grit wet silicone carbide paper. Two such specimens were then cemented together face-to-face with freshly mixed cement, and moderate finger pressure was applied to squeeze the cement to a thin and uniform film. All cemented specimens were then kept in a thermostatic humidor cabinet regulated at $23{\pm}2^{\circ}C.$ and more than 95 per cent relative humidity and tested after 24 hours and 1 week. Link chain was attached to each alloy specimen to reduce the rigidity of the jig assembly, and then all the specimens were mounted in the grips of the Instron Universal Testing Machine, and a tensile load was delivered to the adhering surface at a cross head speed of 0.20 mm/min. The loads to which the specimens were subjected were recorded on a chart moving at 0.50 mm/min. The adhesive strength was determined by measuring the load when the specimen separated from the cement block and by dividing the load by the area. The test was performed in a room at $23{\pm}2^{\circ}C.$ and $50{\pm}10$ per cent relative humidity. A minimum of five specimens were tested each material and those which deviated more than 15 per cent from the mean were discarded and new specimens prepared. From the experiments, the following results were obtained. 1) It was found that the adhesive strength of the polycarboxylate cement to all alloys tested was considerably greater than that of the zinc phosphate cement. 2) The adhesive strength of the polycarboxylate cements was superior to the non precious alloys, such as the copper, indium, nickel and chromium alloys, but it was inferior to the precious gold, silver and palladium alloys. 3) Surface treatment of the alloy was found to be an important factor in achieving adhesion. It appears that a polycarboxylate cement will adhere better to a smooth surface than to a rough one. This contrasts with zinc phosphate cements, where a rough helps mechanical interlocking. 4) The adhesion of the polycarboxylate cement with enamel was found superior to its adhesion with dentine.

• 한국염색가공학회지
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• 제28권1호
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• pp.48-56
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• 2016

Improvement of heat sink technology related to the continuous implementation performance and extension of device-life in circumstance of easy heating and more compact space has been becoming more important issue as multi-functional integration and miniaturization trend of electronic gadgets and products has been generalized. In this study, it purposed to minimize of decline of the heat diffusivity by gluing polymer through compounding of inorganic particles which have thermal conductive properties. We used NH-9300 as base resin and used inorganic fillers such as silicon carbide(SiC), aluminum nitride(AlN), and boron nitride(BN) to improve heat diffusivity. After making film which was made from 100 part of acrylic resin mixed hardener(1.0 part more or less) with inorganic particles. The film was matured at $80^{\circ}C$ for 24h. Diffusivity were tested according to sorts of particles and density of particles as well as size and structure of particle to improve the effect of heat sink in view of morphology assessing diffusivity by LFA(Netzsch/LFA 447 Nano Flash) and adhesion strength by UTM(Universal Testing Machine). The correlation between diffusivity of pure inorganic particles and composite as well as the relation between density and morphology of inorganic particles has been studied. The study related morphology showed that globular type had superior diffusivity at low density of 25% but on the contarary globular type was inferior to non-globular type at high density of 80%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.467-468
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• 2009

For the manufacture of the $CuGaS_2$, Cu, Ga and S were vapor-deposited in the named order. Among them, Cu and Ga were vapor-deposited by using the Evaporation method in consideration of their adhesive force to the substrate so that the composition of Cu and Ga might be 1 : 1, while the surface temperature having an effect on the quality of the thin film was changed from R.T.[$^{\circ}C$] to $150[^{\circ}C$] at intervals of 50[$^{\circ}C$]. As a result, at 300[$^{\circ}C$]of the Annealing temperature, their chemical composition was measured in the proportion of 1 : 1 : 2. It could be known from this experimental result that it is the optimum condition to conduct Annealing on the $CuGaS_2$ thin film under a vacuum when the $CuGaS_2$ thin film as an optical absorption layer material for a solar cell is manufactured.