Characterization of a Hybrid Cu Paste as an Isotropic Conductive Adhesive

Yong-Sung Eom,Kwang-Seong Choi,Seok-Hwan Moon,Jun-Hee Park,이종현 한국전자통신연구원 2011 ETRI Journal Vol.33 No.6

As an isotropic conductive adhesive, that is, a hybrid Cu paste composed of Cu powder, solder powder, and a fluxing resin system, has been quantitatively characterized. The mechanism of an electrical connection based on a novel concept of electrical conduction is experimentally characterized using an analysis of a differential scanning calorimeter and scanning electron microscope energy-dispersive X-ray spectroscopy. The oxide on the metal surface is sufficiently removed with an increase in temperature, and intermetallic compounds between the Cu and melted solder are simultaneously generated, leading to an electrical connection. The reliability of the hybrid Cu paste is experimentally identified and compared with existing Ag paste. As an example of a practical application, the hybrid Cu paste is used for LED packaging, and its electrical and thermal performances are compared with the commercialized Ag paste. In the present research, it is proved that, except the optical function, the electrical and thermal performances are similar to pre-existing Ag paste. The hybrid Cu paste could be used as an isotropic conductive adhesive due to its low production cost.

Oxidation Stability of Conductive Copper Paste Prepared through Electron Beam Irradiation

Ji Hyun Park,Chang Woo Kim,Byung Cheol Lee 한국진공학회(ASCT) 2020 Applied Science and Convergence Technology Vol.29 No.5

For producing printed electronics, Cu is an effective material as it overcomes the limitations of traditional noble metals in terms of cost and availability. Hence, this work involved developing a synthesis method for conductive pastes used in printed electronics with electron beam (e-beam) irradiation. Cu nanoparticles with high oxidation stability were prepared by adjusting the absorbed dose of e-beam irradiation. The high stable Cu nanoparticles, even though exposure to air for 75 days, were used for preparing conductive ink pastes. The electrical conductivity of the Cu conductive pastes was studied under different sintering conditions. Among the conductive pastes coated on glass substrates under various heat treatment conditions, the paste prepared under the formic acid atmosphere formed a porous, thin film with well-connected particles. Further, we observed that sheet resistance increased as the Cu₂O volume fraction and crystalline domain size increased. Thus, e-beam irradiation is a suitable process for mass production of conductive nanoparticles owing to its simplicity and fast reaction time.

Oligomer 특성에 따른 Touch Panel용 UV 경화형 Ag paste의 물성연구

남수용 ( Su Yong Nam ),구용환 ( Yong Hwan Koo ),김성빈 ( Sung Bin Kim ) 한국화상학회 2010 한국화상학회지 Vol.16 No.3

최근 전자 디스플레이에서 각광받고 있는 터치스크린은 급속한 정보화 사회 속에서 비약적인 발전을 거듭하고 있다. 터치패널은 키보드나 마우스와 같은 입력장치를 사용하지 않고, 화면에 나타난 문자나 특정위치에 사람의 손 또는 물체가 닿으면 그 위치를 파악하여 특정한 기능을 처리하도록 한 패널이다. 이러한 터치스크린에서의 터치패널용 Ag 페이스트는 대부분 열 경화형 페이스트를 사용하고 있다. 이러한 열 경화형 페이스트는 건조공정에 따른 열 에너지 소비와 유기용제에 따른 작업환경 개선의 문제점을 가지고 있다. 본 연구에서는 기존에 사용되는 열 경화형 Ag 페이스트가 아닌 친환경적이고 경제적인 UV 경화형 페이스트를 제조하였다. 현재 시판중인 열 경화형 바인더 대신 UV 경화형 올리고머를 사용하였고 유동특성을 부여하기 위해 단관능 모노머를 첨가하여 전도성 Ag paste 패턴형성을 할 수 있었다. 그 결과 열 경화형 Ag 페이스트만큼 접착력, 경도, 내성 등이 우수하였으며 미세패턴의 재현이 가능했으며 스크린 인쇄를 이용한 친 환경적인 패터닝 기술로서의 가능성을 확인할 수 있었다. The recent spotlight on electronic touch-screen display, a rapid breakthrough in the information society is evolving. Touch panel input device such as a keyboard or mouse without the use of, the on-screen character or a specific location or object on the person`s hand touches a particular feature to identify the location of a panel is to be handled. The touch screen on the touch panel is used in the Ag paste is used mostly for low-curable paste. The thermal-curing paste according to the drying process of thermal energy consumption and improve the working environment of organic solvents have problems. In this study, Ag paste used in the non-thermal curing friendly and cost-effective UV curable paste was prepared. Current commercially available thermal-curable binder, was used instead of the flow characteristics of UV-curable oligomers and monomers with functional groups to give a single conductive Ag paste with the addition of a pattern could be formed. Ag paste as a result, thermal-curing adhesive, hardness, resistance and excellent reproduction of fine patterns and was available with screen printing environmentally friendly could see its potential as a patterning technology.

Preparation of conducting silver paste with Ag nanoparticles prepared by e-beam irradiation

Sohn, Jong Hwa,Pham, Long Quoc,Kang, Hyun Suk,Park, Ji Hyun,Lee, Byung Cheol,Kang, Young Soo Elsevier 2010 Radiation physics and chemistry Vol.79 No.11

<P><B>Abstract</B></P><P>Conducting silver paste was prepared by using Ag nanoparticles which were synthesized by e-beam irradiation method (from KAERI); its conductivity was comparatively determined with Ag nanoparticles which were prepared by thermolysis method (commercial). The silver nanoparticles with the diameter of approximately 150nm size prepared by e-beam irradiation were mixed with glass frit and sintered for 1h at 500°C. It is presumably concluded that the wt% of silver nanoparticle, size distribution and homogenous dispersibility of Ag nanoparticles in the pastes are the critical factors for the high conductivity of the paste. Among the various wt% of silver nanoparticle in the conducting silver pastes, silver paste with 90wt% of silver nanoparticle has the highest conductivity as 1.6×10<SUP>4</SUP>Scm<SUP>−1</SUP>. This conductivity value is 1.6 times higher than the Ag pastes which were prepared with silver nanoparticles obtained by thermolysis method.</P>

무용제 타입 UV경화형 나노 실버 페이스트의 광소결 전후 전도성 평가

장민용,남현진,남수용 한국화상학회 2022 한국화상학회지 Vol.28 No.4

본 연구에서는 용제를 전혀 사용하지않고 UV경화가 가능한 나노 실버 페이스트를 개발하였다. 무용제(solvent-free) 타입으로 개발한 나노 실버 페이스트의 점도 및 점탄성 측정하였다. 그리고 스크린인쇄로 패턴을 인쇄한 후에 UV 경화로 전극도막을 형성시켰다. 형성된 전극도막의 전도성, 연필경도, 접착력에 대해서 평가하였다. 또한 전극 도막 을 광 소결하여 전도성을 평가하였다. 마지막으로 전극도막의 경화특성은 TGA 및 FT-IR로 평가하였다. 이러한 결 과를 정리하면 UV경화만 시켰을 경우에는 전도성, 접착력, 경화특성에 대해서는 Paste(3)이 가장 우수하였다. 그러 나 광소결 후에는 Paste(1)이 가장 우수한 전도성을 얻을수있었다. 그 이유는 10nm 실버 파우더를 사용한 것이 소 결 특성이 가장 우수했기 때문이라고 판단된다. In this study, a nano silver paste capable of UV curing was developed without using any solvent. The viscosity and viscoelasticity of nano silver paste developed as a solvent-free type were measured. And after printing the pattern by screen printing, an electrode coating was formed by UV curing. Conductivity, pencil hardness, and adhesive strength of the formed electrode coating film were evaluated. In addition, the conductivity was evaluated by light sintering the electrode coating film. Finally, the curing characteristics of the electrode coating were evaluated by TGA and FT-IR. Summarizing these results, when only UV curing was performed, Paste(3) was the most excellent in terms of conductivity, adhesive strength, and curing characteristics. However, after photosintering, Paste(1) obtained the best conductivity. I think the reason for this is that the 10nm silver powder had the best sintering properties.

Polymer Gravure Printing용 열경화형 Ag Paste의 물성과 레올로지 특성 연구

구태희,남수용,김성빈,Ku, Tae-Hee,Nam, Su-Yong,Kim, Sung-Bin 한국인쇄학회 2012 한국인쇄학회지 Vol.30 No.2

In this experiment, we have manufactured thermal-curable silver pastes for direct printing. And to enhance conductivity, printability, adhesion and hardness during polymer direct-gravure prints, we have manufactured Ag pastes by adding variety of filter contents. Then we have investigated characteristics of rheology in paste according to the gravure printability and the properties of printed conductive patterns. Depending on a variety of Ag powder, there was a big difference in sharpness of printed pattern. And also by the use of carbon, there was a big difference in amount of solvent used, conductivity and in hardness. We could improve doctoring and the sharpness of a pattern by adding Ag paste in carbon particle, but as we have used nano-sized particle, there was an increase in the amount of solvent used and also we have found out that it gives a bad effect as adhesive and hardness becomes weaker. Even though Ag particle has the same spherical shape, the surface treatments could differ from one another. And by the appropriate choice and with the suitable combination of Ag powder, excellent printability and conductivity could be obtained.

Bioinspired Multifunctional Superhydrophobic Surfaces with Carbon-Nanotube-Based Conducting Pastes by Facile and Scalable Printing

Han, Joong Tark,Kim, Byung Kuk,Woo, Jong Seok,Jang, Jeong In,Cho, Joon Young,Jeong, Hee Jin,Jeong, Seung Yol,Seo, Seon Hee,Lee, Geon-Woong American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.8

<P>Directly printed superhydrophobic surfaces containing conducting nanomaterials can be used for a wide range of applications in terms of nonwetting, anisotropic wetting, and electrical conductivity. Here, we demonstrated that direct-printable and flexible superhydrophobic surfaces were fabricated on flexible substrates via with an ultrafacile and scalable screen printing with carbon nanotube (CNT)-based conducting pastes. A polydimethylsiloxane (PDMS)-polyethylene glycol (PEG) copolymer was used as an additive for conducting pastes to realize the printability of the conducting paste as well as the hydrophobicity of the printed surface. The screen-printed conducting surfaces showed a high water contact angle (WCA) (>150) and low contact angle hysteresis (WCA < 5) at 25 wt % PDMS-PEG copolymer in the paste, and they have an electrical conductivity of over 1000 S Patterned superhydrophobic surfaces also showed sticky superhydrophobic characteristics and were used to transport water droplets. Moreover, fabricated films on metal meshes were used for an oil/water separation filter, and liquid evaporation behavior was investigated on the superhydrophobic and conductive thin-film heaters by applying direct current voltage to the film.</P>

Comparative study on the preparation of conductive copper pastes with copper nanoparticles prepared by electron beam irradiation and chemical reduction

Pham, Long Quoc,Sohn, Jong Hwa,Park, Ji Hyun,Kang, Hyun Suk,Lee, Byung Cheol,Kang, Young Soo Elsevier 2011 Radiation physics and chemistry Vol.80 No.5

<P><B>Abstract</B></P><P>Copper nanoparticles with narrow size distribution of 5–7nm were synthesized by using electron beam irradiation. The copper nanoparticles were stable in ambient air for two months. TGA showed that the copper nanoparticles prepared by using electron beam irradiation have the higher wt% of pure copper metal compared with the one prepared by chemical reduction using hydrazine hydrate(N<SUB>2</SUB>H<SUB>4</SUB>·<I>x</I>H<SUB>2</SUB>O). The conductive copper paste with copper nanoparticles prepared by electron beam irradiation showed higher conductivity than the paste with copper nanoparticles prepared by chemical reduction with N<SUB>2</SUB>H<SUB>4</SUB> due to small size, less amount of surfactants on the surface and higher stability against the oxidation in ambient condition. The highest conductivity of copper paste was determined as 170Scm<SUP>−1</SUP> at 90wt% of copper nanoparticles in the paste.</P> <P><B>Research highlights</B></P><P>► Copper nanoparticles were synthesized by electron beam irradiation and chemical reduction. ► The copper nanoparticles synthesized by electron beam irradiation have narrower size distribution of 5–7nm and higher wt% of pure copper metal compared with the one synthesized by chemical reduction. ► Conductive pastes prepared by copper nanoparticles synthesized by electron beam irradiation show higher conductivity.</P>

친수성 표면개질의 에어로겔을 혼입한 시멘트 페이스트의압축강도 발현 및 열전도율 평가

안태호,박종범,윤현섭,양근혁 한국건축시공학회 2018 한국건축시공학회지 Vol.18 No.1

The objective of the present study is to examine the feasibility on the development of high-insulation concrete usingaerogels with hydrophilic surface treatment. To prevent the segregation and enhance the dispersibility of agerogels in thecement pastes, the substrate of aerogels was modified to be hydrophobic property using surfactant. The modified aerogelswere added from 0% to 100% of the cement volume at the interval of 25% under the constant cement content. Somecement pastes showed segregation phenomenon and flocculation of aerogels during mixing phase. The addition of aerogelsdecreased the compressive strength of cement pastes but enhanced the thermal conductivity. The thermal conductivity ofpastes with 100% aerogels was lower by 43% when compared with that measured in the conventional paste. To improvethe compressive strength and insulation capacity of concrete containing aerogels, a reliable surface treatment method ofaerogels needs to be further investigated. 이 연구의 목적은 친수성 표면개질의 에어로겔을 활용한높은 단열 콘크리트 재료 개발의 기초 평가이다. 시멘트계재료에서 에어로겔의 재료분리 방지 및 분산성 향상을 위하여 소수성 에어로겔의 표면은 계면활성제를 이용하여 친수성을 부여하였다. 시멘트 페이스트에서 에어로겔의 첨가양은 시멘트 부피 대비 0%에서 100%로 변화하였다. 일부 시멘트 페이스트는 배합단계에서 재료분리 및 에어로겔의 뭉침현상이 나타났다. 에어로겔의 혼입은 시멘트 페이스트의압축강도를 저하시키는 반면 열전도율은 향상시켰다. 에어로겔을 100% 첨가한 페이스트의 열전도율은 일반 페이스트대비 약 43% 낮았다. 에어로겔 혼입 콘크리트의 압축강도와단열성 향상을 위해서는 에어로겔의 최적 표면개질에 대한연구가 요구되었다.

전도성 페이스트 도포량 변화에 따른 결정질 태양광 모듈의 전기적 특성에 대한 영향성 분석

김용성,임종록,신우균,고석환,주영철,황혜미,장효식,강기환,Kim, Yong Sung,Lim, Jong Rok,Shin, Woo Gyun,Ko, Suk-Whan,Ju, Young-Chul,Hwang, Hye Mi,Chang, Hyo Sik,Kang, Gi-Hwan 한국재료학회 2019 한국재료학회지 Vol.29 No.11

Recently, research on cost reduction and efficiency improvement of crystalline silicon(c-Si) photovoltaic(PV) module has been conducted. In order to reduce costs, the thickness of solar cell wafers is becoming thinner. If the thickness of the wafer is reduced, cracking of wafer may occur in high temperature processes during the c-Si PV module manufacturing process. To solve this problem, a low temperature process has been proposed. Conductive paste(CP) is used for low temperature processing; it contains Sn57.6Bi0.4Ag component and can be electrically combined with solar cells and ribbons at a melting point of $150^{\circ}C$. Use of CP in the PV module manufacturing process can minimize cracks of solar cells. When CP is applied to solar cells, the output varies with the amount of CP, and so the optimum amount of CP must be found. In this paper, in order to find the optimal CP application amount, we manufactured several c-Si PV modules with different CP amounts. The amount control of CP is fixed at air pressure (500 kPa) and nozzle diameter 22G(outer diameter 0.72Ø, inner 0.42Ø) of dispenser; only speed is controlled. The c-Si PV module output is measured to analyze the difference according to the amount of CP and analyzed by optical microscope and Alpha-step. As the result, the optimum amount of CP is 0.452 ~ 0.544 g on solar cells.