• 한국레이저가공학회:학술대회논문집
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• 한국레이저가공학회 2006년도 추계학술발표대회 논문집
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• pp.53-81
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• 2006

A COG(Chip on Glass) bonding process that is one of display packaging technology and bonds between driver IC chip and a glass panel using ACF(Anisotropic Conductive Film)has been investigated by using diode laser. This method is possible to raise cure temperature of ACF within one second and can reduce the total process time for COG bonding by a conventional method such as a hot plate. Also we can get good pressure mark on the surface of electrodes and higher bonding strength than that by convention method. Results show that laser COG bonding can give low pressure bonding and decrease a warpage of panel. We believe that it can be applied to fine pitch module.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 추계학술대회 논문집
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• pp.423-426
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• 2005

A new chip on glass(COG) technique by making use of a high power diode laser for LCD driver IC packaging of LCD has been developed. A laser joining technology of the connection of IC chip to glass panel has several advantages over conventional method such as hot plate joining: shorter process time, high reliability of joining, and better fur fine pitch joining. The reach time to cure temperature of ACF in laser joining is within 1 second. In this study, results show that the total process time of joining is reduced by halves than that of conventional method. The adhesion strength is mainly 100-250 N/cm. It is confirmed that the COG technology using high power diode laser joining can be applied to advanced LCDs with a fine pitch.

• 제어로봇시스템학회논문지
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• 제16권2호
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• pp.172-176
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• 2010

Recently, LCD (Liquid Crystal Display) requires various technical challenges; high definition, high quality, big size, and low price. These demands more pixels in the fixed area of the LCD and very fine lead pitch of the driving IC which controls the pixels. Therefore, a new packaging technology is needed to meet such technical requirement. NCP (Non Conductive Paste) is one of the new packaging methods and has excellent characteristics to overcome the problems of the ACF (Anisotropic Conductive Film). In this paper, we analyzed the process of the NCP for COF (Chip on FPCB) and proposed the key design parameters of the NCP process. Through a series of experiments, we obtained the stable values of the design parameters for successful NCP process.

• 한국정밀공학회지
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• 제27권7호
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• pp.28-35
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• 2010

In the display industry, COG bonding method is being applied to production of LCD panels that are used for mobile phones and monitors, and is one of the mounting methods optimized to compete with the trend of ultra small, ultra thin and low cost of display. In COG bonding process, electrical characteristics such as contact resistance, insulation property, etc and mechanical characteristics such as bonding strength, etc depend on properties of conductive particles and epoxy resin along with ACF materials used for COG by manufacturers. As the properties of such materials have close relation to optimization of bonding conditions such as temperature, pressure, time, etc in COG bonding process, it is requested to carry out an in-depth study on characteristics of COG bonding, based on which development of bonding process equipment shall be processed. In this study were analyzed the characteristics of COG bonding process, performed the analysis and reliability evaluation on electrical and mechanical characteristics of COG bonding using ACF to find optimum bonding conditions for ACF, and performed the experiment on bonding characteristics regarding fine pitch to understand the affection on finer pitch in COG bonding. It was found that it is difficult to find optimum conditions because it is more difficult to perform alignment as the pitch becomes finer, but only if alignment has been made, it becomes similar to optimum conditions in general COG bonding regardless of pitch intervals.

• 마이크로전자및패키징학회지
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• 제22권1호
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• pp.35-41
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• 2015

In this study, in order to improve the reliability of ACF interconnections, solder ACF joints were investigated interms of solder joint morphology and solder wetting areas, and evaluated the electrical properties of Flex-on-Board (FOB) interconncections. Solder ACF joints with the ultrasonic bonding method showed excellent solder wetting by broken solder oxide layers on solder surfaces compared with solder joints with remaining solder oxide layer bonded by the conventional thermo-compression (TC) bonding method. When higher target temperature was used, Sn58Bi solder joints showed concave shape due to lower degree of cure of resin at solder MP by higher heating rate. ACFs with epoxy resins and SAC305 solders showed lower degree of resin cure at solder MP due to the slow curing rate resulting in concave shaped solder joints. In terms of solder wetting area, solder ACFs with $25-32{\mu}m$ diameters and 30-40 wt% showed highest wetted solder areas. Solder ACF joints with the concave shape and the highest wetting area showed lower contact resistances and higher reliability in PCT results than conventional ACF joints. These results indicate that solder morphologies and wetting areas of solder ACF joints can be controlled by adjustment of bonding conditions and material properties of solder and polymer resin to improve reliability of ACF joints.

• ETRI Journal
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• 제38권6호
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• pp.1163-1171
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• 2016

Integration technologies involving flexible substrates are receiving significant attention owing the appearance of new products regarding wearable and Internet of Things technologies. There has been a continuous demand from the industry for a reliable bonding method applicable to a low-temperature process and flexible substrates. Up to now, however, an anisotropic conductive film (ACF) has been predominantly used in applications involving flexible substrates; we therefore suggest low-temperature lead-free soldering and bonding processes as a possible alternative for flex-on-flex applications. Test vehicles were designed on polyimide flexible substrates (FPCBs) to measure the contact resistances. Solder bumping was carried out using a solder-on-pad process with Solder Bump Maker based on Sn58Bi for low-temperature applications. In addition, thermocompression bonding of FPCBs was successfully demonstrated within the temperature of $150^{\circ}C$ using a newly developed fluxing underfill material with fluxing and curing capabilities at low temperature. The same FPCBs were bonded using commercially available ACFs in order to compare the joint properties with those of a joint formed using solder and an underfill. Both of the interconnections formed with Sn58Bi and ACF were examined through a contact resistance measurement, an $85^{\circ}C$ and 85% reliability test, and an SEM cross-sectional analysis.

• 마이크로전자및패키징학회지
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• 제14권3호
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• pp.21-27
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• 2007

이방성 전도필름(ACF) 접합에 사용되는 니켈 범프를 무전해 및 전해 도금법으로 제작한 다음, 이 범프들의 기계적 특성과 충격안전성을 압축시험, 범프전단시험, 낙하충격시험을 통하여 연구하였다. Nano indenter를 이용한 압축시험에서 얻은 하중-변형량 데이터를 변환시켜 니켈범프의 응력-변형량 곡선을 구하였다. 전해 니켈 범프는 무전해 니켈 범프에 비해 매우 작은 탄성한계응력과 탄성계수를 나타냈었다. 무전해 니켈 범프의 탄성한계응력과 탄성계수가 각각 600-800MPa, $9.7{\times}10^{-3}MPa/nm$인 반면 전해 니켈 범프의 경우에는 각각 70MPa, $7.8{\times}10^4MPa/nm$이었다. 범프전단 시험에서 무전해 니켈 범프는 소성변형이 거의 일어나지 않고 낮은 전단하중에서 범프가 패드 층에서 튕기듯이 떨어져 나간 반면 전해 니켈 범프는 큰 소성변형을 일으키며 범프가 잘려나갔으며 높은 전단하중을 보여주었다. 낙하충격시험 결과 ACF 플립칩 방법으로 본딩한 무전해 및 전해 범프 모두 높은 충격 신뢰성을 보였다.

• 마이크로전자및패키징학회지
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• 제8권4호
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• pp.59-65
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• 2001

경화 전 상온 보관성이 우수하며 넓은 면적에 균일한 두께와 균일한 유전특성의 커패시터를 쉽게 형성할 수 있는 epoxy/$BaTiO_3$composite커패시터 필름을 제조하였다. 이 필름은 필름 형성특성과 가공성, 그리고 상온 보관성이 우수한 에폭시계 이방성 전도 필름(Anisotropic Conductive Film: ACF)용으로 개발된 레진을 기본으로 하고, 유전상수를 높이기 위한 충진제로 2종류의 $BaTiO_3$분말을 사용하였다. X선 회절을 통하여 두 분말의 결정구조와 이에 따른 유전상수의 변화를 살펴보았으며, 점포 측정을 통해 분산제의 양을 정하였다. 필름의 경화온도와 적정한 경화제의 양을 결정해주기 위해 differential scanning calorimeter (DSC)와 커패시터의 특성 분석을 통해 경화제 양에 따른 필름 및 커패시터 특성에 미치는 영향을 살펴보았다. 이 필름을 이용하여 두께 7 $\mu\textrm{m}$에서 10 nF/$\textrm{cm}^2$ (이때의 유전상수는 80)의 높은 전기용량을 가진 우수한 커패시터를 성공적으로 제작하였다.

• 한국항해항만학회지
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• 제27권2호
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• pp.217-221
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• 2003

본 논문에서는 새로운 형태의 CSP (chip site package)를 이용하여 정합소자 린 바이어스소자를 MMIC상에 완전집적한 Ku/K밴드 광대역 증폭기 MMIC에 관하여 보고한다. 새로운 형태의 CSP에 대해서는 이방성 도전필름인 ACF (anisotropic conductive film)을 이용하였으며, 그 결과 MMIC 패키지 프로세스가 간략화 되었고, CSP MMIC의 저 가격화가 실현되었다. MMIC상에 집적하기 위한 DC 바이어스 용량소자로서는 고유전율의 STO (SrTiO3) 필름 커패시터가 이용되었다. 제작된 CSP MMIC는 광대역 RF동작특성 (12-24 GHz에서 12.5$\pm$1.5 dB의 이득치, -6 dB이하의 반사계수, 18.5$\pm$1.5 dBm의 PldB) 을 보였다. 본 논문은 K 또는 Ku 밴드의 주파수대역에 있어서의 완전집적화 CSP MMIC에 관한 최초의 보고이다.

• 한국전기전자재료학회논문지
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• 제21권3호
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• pp.265-271
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• 2008

TCP(Tape Carrier Package), COG (Chip On Glass), COF(Chip On Film) are three methods for connecting LDI(LCD Driver IC) with LCD panels. Especially COF is growing its portion of market place because of low cost and fine pitch correspondence. But COF has a problem of the lead broken failure in LCD module process and the usage of customer. During PCB (Printed Circuit Board) bonding process, the mismatch of the coefficient of thermal expansion between PCB and D-IC makes stress-concentration in COF lead, and also D-IC bending process during module assembly process makes the level of stress in COF lead higher. As an affecting factors of lead-broken failure, the effects of SR(Solder Resister) coating on the COF lead, surface roughness and grain size of COF lead, PI(Polyimide) film thickness, lead width and the ACF(Anisotropic Conductive Film) overlap were studied, The optimization of these affecting manufacturing processes and materials were suggested and verified to prevent the lead-broken failure.