• Journal of the Korean Institute of Telematics and Electronics A
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• v.28A no.10
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• pp.840-846
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• 1991

In case of the rapid thermal process by halogen lamps, an optical pyrometer is generally used to measure the temperature. It is, however, necessary to measure the temperature by the thermocouple when the process temperature is lower than 700$^{\circ}C$ and the correction of the temperature is required. Contact by the PdAg paste is commonly used out but in this case it is impossible to see the effect of surface states of the substrate, which is critical in the rapid thermal process. In this study, real temperature ramping speed of silicon substrates coveredwith various thin films such as SiO$_2$2, Si$_{3}N_{4}$, dopants, and conductive layers (Ti or Co) was investigated by a mechanical contact of the thermocouple. And the results were compared with the case in which the contact was made by the PdAg paste. Effect of process ambient was also studied. It was found that depending on the surface state, overshoot more than 100$^{\circ}C$ could occur. It was also found that in case of the substrate covered with conductive layers, mechanical contact might render the correct temperature.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1076-1077
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• 2006

Conductive pastes consist of conductive fillers( Au, Ag, Ni, Cu etc.), organic binders, solvents and additives. Meanwhile, there are some metal powders such as copper, nickel etc that are used for pastes which have serious surface corrosion problems. This problem leads to change of the color and decrease in conductivity and affect storage stability of conductive pastes. By using silane coupling agent and dispersion agent, we can ensure both the corrosion stability and long term storage stability, and enhance the high performance electrical and mechanical properties of EMI shielding silicone sealant.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.1
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• pp.51-54
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• 2015

An electro-plating technology on a cured isotropic conductive pattern with a hybrid Cu paste composed of resin matrix, copper, and solder powders has been developed. In a conventional technology, Ag paste was used to perform a conductive pattern on a PCB or silicon substrate. From previous research, the electrical conductive mechanism and principle of the hybrid Cu paste were concisely investigated. The isotropic conductive pattern on the PCB substrate was performed using screen-printing technology. The optimum electro-plating condition was experimentally determined by processing parameters such as the metal content of the hybrid Cu paste, applied current density, and time for the electroplating in the plating bath. The surfaces and cross-sections were observed using optical and SEM photographs. In conclusion, the optimized processing conditions for Cu electro-plating technology on the conductive pattern were a current density of $40mA/cm^2$ and a plating time of 20min on the hybrid Cu paste with a metal content of 44 vol.%. More details of the mechanical properties and processing conditions will be investigated in further research.

• Journal of Biomedical Engineering Research
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• v.43 no.4
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• pp.219-229
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• 2022

In this study, we propose a miniaturized micro-ceramic heater device. After screen-printing a silver paste between pre-sintered two aluminum oxide plates to integrate a heating circuit, the device was fabricated through a low-temperature sintering process. In order to configure the optimal heating circuit integration condition, the output current evaluation and heating test were performed according to the number of screen prints of the silver paste at various voltages. A silver paste-based heating circuit printed with a line width of 200 ㎛ and a thickness of 60 ㎛ was successfully integrated on a pre-sintered alumina substrate through a low-temperature sintering process. In the case of the 5 times printed device, the thermal response showed a response rate of 18.19 ℃/sec. To demonstrate feasibility of the proposed device in the medical field, such as bio-tissue suturing and hemostasis, a voltage was applied to pig tissue in the device to test tissue change due to heat generated from the device. These results show the possibility that the proposed small ceramic heater could be used in the medical field based on its excellent temperature response.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.4
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• pp.41-47
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• 2022

Ag sintering technologies have received great attention as it was applied to the inverter of Tesla's electric vehicle Model III. Ag sinter bonding technology has advantages in heat dissipation design as well as high-temperature stability due to the intrinsic properties of the material, so it is useful for practical use of SiC and GaN devices. This study was carried out to understand the sinter joining temperature effect on the robust Ag sintered joints in air without pressure within 10 min. Electroplated Ag finished Cu dies (3 mm × 3 mm × 2 mm) and substrates (10 mm × 10 mm × 2 mm) were introduced, respectively, and nano Ag paste was applied as a bonding material. The sinter joining process was performed without pressure in air with the bonding temperature as a variable of 175 ℃, 200 ℃, 225 ℃, and 250 ℃. As results, the bonding temperature of 175 ℃ caused 13.21 MPa of die shear strength, and when the bonding temperature was raised to 200 ℃, the bonding strength increased by 157% to 33.99 MPa. When the bonding temperature was increased to 225 ℃, the bonding strength of 46.54 MPa increased by about 37% compared to that of 200 ℃, and even at a bonding temperature of 250 ℃, the bonding strength exceeded 50 MPa. The bonding strength of Ag sinter joints was directly influenced by changes in the necking thickness and interfacial connection ratio. In addition, developments in the morphologies of the joint interface and porous structure have a significant effect on displacement. This study is systematically discussed on the relationship between processing temperatures and bonding strength of Ag sinter joints.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.7
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• pp.83-89
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• 2019

In the conventional casting and forging method, there is a disadvantage that a mold is an essential addition, and a production cost is increased when a small quantity is produced. In order to overcome this disadvantage, a metal 3D printing production method capable of directly forming a shape without a mold frame is mainly used. In particular, overseas research has been conducted on various materials, one of which is a metal printer. Similarly, domestic companies are also concentrating on the metal printer market. However, In this case of the conventional metal 3D printing method, it is difficult to meet the needs of the industry because of the high cost of materials, equipment and maintenance for product strength and production. To compensate for these weaknesses, printers have been developed that can be manufactured using sand mold, but they are not accessible to the printer company and are expensive to machine. Therefore, it is necessary to supply three-dimensional casting printers capable of metal molding by producing molds instead of conventional metal 3D printing methods. In this study, we intend to reduce the unit price by replacing the printing method used in the sand casting printer with the FDM method. In addition, Ag paste is used to design the output conditions and enable ceramic printing.

• Analytical Science and Technology
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• v.20 no.5
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• pp.393-399
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• 2007

In principle, the blood galactose level may be determined conveniently with a strip-type biosensor similar to that for glucose. In this study, we describe the development of a disposable galactose biosensor strip for point-of-care testing. The sensor strip is constructed with screen-printed carbon paste electrode (SPCE) and sample amount (< $100{\mu}L$). The developed strip the galactose level in less than 90 s using bienzymatic system of galactose oxidase (GAO) and horseradish peroxidase (HRP). The effects of pH, mediator (1,1-ferrocenedimethanol) concentration, ratio of enzymes, and applied potential were determined preliminarily with glassy carbon electrodes, and optimized further with the strip-type electrodes. The sensor exhibits linear response in the range of $0{\sim}400{\mu}M$ ($r^2$ = 0.997, S/N = 3). Since a low working potential, in principle, the fabricated disposable galactose biosensor has -100 mV (vs. Ag/AgCl), it is applied for the detection of galactose, interfering responses from common interferents such as ascorbic acid, uric acid and acetaminophen could be minimized. The sensor has been used to determine the total galactose level in standard samples with satisfactory reproducibility (CV = 5 %).

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.122.2-122.2
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• 2015

n-type 실리콘은 p-type과 비교하여 더 높은 소수캐리어 lifetime 으로 금속 불순물에 대하여 더 좋은 내성을 갖는다. 고효율 실리콘 태양전지를 위하여 p-type 웨이퍼를 n-type으로 교체하여 빛을 조사했을 때, 광전자들이 형성되어 p-type과 비교하여 더 좋은 lifetime 안정성을 갖는다. n-type 태양전지의 전면 전극은 AgAl paste로 형성하였다. AgAl 페이스트는 소성 온도와 밀접하게 관련되어 전극의 접합 깊이에 영향을 미친다. p+ emitter 층에 파고드는 금속 접촉의 최적화된 깊이는 접촉 저항에 영향을 미치는 중요한 요소이다. 본 연구에서는 소성 조건을 변화시킴으로써, 금속 깊이의 효과적인 형성을 위한 소성 조건을 최적화하였다. $670^{\circ}C$ 이하의 온도에서 소성을 진행 하였을 때, 충분한 접촉 깊이를 형성하지 못하여 높은 접촉저항을 갖는다. 소성 온도가 증가함에 따라, 접촉 저항은 감소하였다. 최적 소성 온도 $865^{\circ}C$에서 측정된 접촉저항은 $5.99mWcm^2$이다. $900^{\circ}C$ 이상에서 contact junction은 emitter를 통과하여 실리콘과 결합하였다. 그 결과로 접촉저항 shunt가 발생한다.

• Analytical Science and Technology
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• v.13 no.3
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• pp.315-322
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• 2000

The response characteristics of the bioelectrode developed by the co-immobilization of spinach root tissue and ferrocene in a carbon paste matrix for the amperometric determination of hydrogen peroxide were evaluated. In the range of electrode potential examined (-0.3~0.0V vs. Ag/AgCl). the response time was relatively short ($t_{95%}=11.8$ sec) and it responded in the wide range of pH. Also, its detection limit was $2.25{\times}10^{-6}M$ (S/N=3) and a relative standard deviation of the measurements which were repeated 15 times using $1.0{\times}10^{-3}M$ hydrogen peroxide was 1.87%. The bioelectrode sensitivity decreased to 40% of the original value in 19 days of continuous use.

• Journal of the Korean Chemical Society
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• v.41 no.7
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• pp.343-350
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• 1997

The response characteristics of a new biosensor, which was developed by co-immobilisation of chicken liver tissue and ferrocene in a carbon paste matrix for the amperometric determination of hydrogen peroxide, was evaluated. In the range of electrode potential observed ( - 0.5∼ + 0.05 V vs Ag/AgCl), the bioelectrode showed the response time ($t_{95%}$) as low as 13 sec and the detection limit of $5.1{\times}10^{-5}$ M, and exhibited a good selectivity in the case of the addition of the possible interferents tested. Also it offered a high biocatalytic stability and opened up the possibility for the construction of a mediatorless biosensor.