• Korean Journal of Metals and Materials
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• v.50 no.8
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• pp.563-568
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• 2012

The wetting property and reflectivity of Sn-3.5Ag solder which was dip coated on a LED lead frame were investigated. The wettability of molten solder on Cu substrate was evaluated by the wetting balance tester, and surface tension was calculated from maximum withdrawal force and withdrawal time. Temperature of the molten solder in a bath was varied in the range of $250-290^{\circ}C$. With increasing temperature, the surface tension decreased a little. The reflectivity of Sn-3.5Ag coated on a substrate became a little lower than the highest current LED lead frame reflectivity.

• Journal of Welding and Joining
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• v.18 no.6
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• pp.74-82
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• 2000

The fluxless wetting properties of UBM-coated Si-wafer to the binary lead-free solders(Sn-Ag, Sn-Sb, Sjn-In, Sn0Bi) were estimated by wetting balance method. With the new wettability indices from the wetting curves of one side coated specimen, the wetting property estimation of UBM-coated Si-wafer was possible. For UBM of Si-chip, Au/Cu/Cr UBm was better than au/Ni/TI in the point of wetting time/ At general reflow process temperature, the wettability of high melting point solders(Sn-Sb, Sn-Ag) was better than that of low melting point one(Sn-Bi, Sn-In). The contact angle of the one side coated Si-plate to the solder could be calculated from the force balance equation by measuring the static state force and the tilt angle.

• Journal of Welding and Joining
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• v.20 no.5
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• pp.106-112
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• 2002

In the present study, the wettability and interfacial tension between (bare Cu, electroless Ni/cu, immersion Au/Ni/Cu) substrates and indium solder were investigated as a function of soldering temperature, types of flux. The wettability of In solder increased with soldering temperature and solid content of flux. The wettability of In solder was affected by the substrate metal finish used, i.e., nickel, gold and copper. On the bare Cu substrate, In solder wet better than any of the substrate metal finishes tested. Intermetallic compound formation between liquid solder and substrate reduced the interfacial energy and improved wettability. For the identification of intermetallic compounds, X-Ray Diffraction(LRD) were employed. Experimental results showed that the intermetallic compounds, such as Cu11In9 and In27Ni10 are observed f3r different substrates respectively. The wetting kinetics is investigated by measuring wetting time with the wetting balance technique. The activation energy of wetting calculated for the In solder/cu substrate and In solder/electroless Au/Ni/Cu substrate are 36.13 and 27.36 kJ/mol, respectively.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2000.04a
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• pp.74-79
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• 2000

In an attempt to estimate the wetting properties of wettable metal layers by wetting balance method, an analysis of wetting curves of the coating layer was performed. Based on the analysis, wetting properties of UBM-coated Si-plate were estimated by the new wettability indices. The wetting curves of the one and both sides-coated UBM layers have the similar shape and show the similar tendency to the temperature. So the wetting property estimation of one side coating is possible with wetting balance method. For UBM of Si-chip, Cr/Cu/Au UBM is better than Ti/Ni/Au in the point of wetting time. At general reflow temperature, the wettability of high melting point solders(Sn-Sb, Sn-Ag) is better than that of few melting point ones(Sn-Bi, Sn-In).The contact angle of the one side coated plate to the solder can be calculated from the farce balance equation by measuring the static state force and the tilt angle.

• Journal of the Korean Ceramic Society
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• v.36 no.9
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• pp.991-996
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• 1999

Effect of solution property on the weight varation and microstructural change of film was studied by electrophoretic deposition in order to obtain a homogeneous and dense zirconia film. As a result of weight kinetics of film which obtained in alcohol or aqueous solution having different polarity experimental data showed large deviation from theoretical ones calculated by Zhang's kinetic model. It had been shown that the weight affecting factors was largely dependent on properties other than dielectric constant and viscosity of solvent zeta potential appiled field and time. In initial stage a main factor of the drastic weight increase was the capillary drag of porous substrate. The cause of weight decrease with time in aqueous solution after 300 s was attributed to the defect of film by sagging and electrolytic reaction. The electrolyte film which prepared in alcohol solution with good wetting for substrate had better homogeneous and dense microstructure than one in aqueous solution with high surface tension.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.2
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• pp.55-62
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• 2000

The wetting balance test was performed in an attempt to estimate the wetting properties of the UBM-coated Si-wafer on one side to the Sn-Pb solder. The wetting curves of the one and both side-coated UBM layers had the similar shape and the parameters characterizing the curve shape showed the similar transition tendency to the temperature. The wetting property estimation was possible with the new wettability indices from the wetting curves of one side-coated specimen; $F_{min}$, $F_{s}t_{s}$ and $t_s$. For UBM of Si-chip, Au/Cu/Cr UBM was better than Au/Ni/Ti in the point of wetting time. The contact angle of the one side coated Si-plate to the Sn-Pb solder could be calculated from the force balance equation by measuring the static state force and the tilt angle.

• Journal of the Korean institute of surface engineering
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• v.35 no.1
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• pp.11-16
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• 2002

As environmental concerns increasing, the electronics industry is focusing more attention on lead free solder alternatives. In this research, we have researched wettability of intermediate solder of Sn3Ag9Bi5In, which include In and Bi and has similar melting temperature to Sn37Pb eutectic solder. We investigated the wetting property of Sn3Ag9Bi5In. To estimate wettability of Sn3Ag9Bi5In solder on various substrates, the wettability of Sn3Ag9Bi5In solder on high-pure Cu-coupon was measured. Cu-coupon that plated Sn, Ni and Au/Ni and Si-wafer adsorbed Ni/Cu under bump metallurgy on one side. As a result, the wetting property of Sn3Ag9Bi5In solder is a little better than that of Sn37Pb and Sn3.5Ag.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.425-426
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• 2010

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.179.2-179.2
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• 2014

Carbon nanotubes (CNT)-metal contacts play an important role in nanoelectronics applications such as field-effect transistor (FET) devices. Using Al and (10,0) CNT, we have recently showed that the CNT-metal contacts mediated via topological defects within CNT exhibits intrinsically low contact resistance, thanks to the preservation of the sp2 bonding network at the metal-CNT contacts.[1] It is well-established that metals with good wetting property such as Pd consistently yield good contacts to both metallic and semiconducting CNTs. In this work, the electronic and charge transport properties of the interfaces between capped CNT and Pd will be investigated based on first-principles computations and compared with previous results obtained for the Al electrodes.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2011.05a
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• pp.184-185
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• 2011

In this study, in order to obtain a high reflectivity for the LED lead frame, tin dip coating and tin plating were conducted respectively, and wettability of LED lead frame with tin solder also was tested by wetting balance tester. A Cu sheet was plated in Cu brighten electroplating bath and followed by immersion in a Sn electro-less plating bath [1]. On the other hand, in the dip coating process, a Cu sheet was dipped into molten tin. In the progress of wetting test, besides wetting balance curve, the maximum measured force($F_m$), the maximum withdrawal force($F_w$) and zero-cross time($t_0$) were obtained in various temperatures. With the maximum withdrawal force, the surface tension was calculated at different temperatures. The Cu sheet plated with bright Cu and Sn show a silver bright property while that of Cu dipped with Sn possessed a high reflectance density of 1.34GAM at $270^{\circ}C$.