• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.23 no.6
• /
• pp.481-486
• /
• 2010

ENIG (electroless Ni immersion gold) is one of surface finishing which has been most widely used in fine pitch SMT (surface mount technology) and BGA (ball grid array) packaging process. The reliability for package bondability is mainly affected by interfacial reaction between solder and surface finishing. Since the behavior of IMC (intermetallic compound), or the interfacial reaction between Ni and solder, affects to some product reliabilities such as solderability and bondability, understanding behavior of IMC should be important issue. Thus, we studied the properties of ENIG with P contents (9 wt% and 13 wt%), where the P contents is one of main factors in formation of IMC layer. The effect of P content was discussed using the results obtained from FE-SEM(field-emission scanning electron microscope), EPMA(electron probe micro analyzer), EDS(energy dispersive spectroscopy) and Dual-FIB(focused ion beam). Especially, we observed needle type irregular IMC layer with decreasing Ni contents under high P contents (13 wt%). Also, we found how IMC layer affects to bondability with forming continuous Kirkendall voids and thick P-rich layer.

• Journal of the Korean Magnetics Society
• /
• v.3 no.1
• /
• pp.7-12
• /
• 1993

The effects of Mn, Cr or Co addItion on the magnetic properties of Fe-Ni Invar alloys were investigated. The composition range of the three additives is up to 5wt%. In the temperature range of room temperature-$250^{\circ}C$, the variation of specific magnetization with the addition of Mn, Cr or Co in the Fe-Ni alloys except for 5wt% Co shows the phenomenon characteristics of the Invar effect, viz., the specific magnetization decreases very abrubtly with the temperature and the dependence of temperature on the specific magnetization is in the mixed form of $T^{3/2}$ and $T^{2}$. In the room temperature, the amount of increase in the specific magnetization, Curie temperature and coercivity is in order of Co > Cr > Mn. In the case of 5wt% Co an anomalous phenomena were observed due to the occurrance of ferromagnetic $\alpha$ phase which reduces the invar effect.

• Journal of Environmental Health Sciences
• /
• v.16 no.2
• /
• pp.97-103
• /
• 1990

For this study, I used the urine of 100 dental laboratroy technicians and 24 students in Chonbuk region. The purposes of this study were to investigate concentrations of cadmium (Cd), nickel (Ni) and chromium (Cr) in the air of dental laboratories. The results were as follows: 1. The concentrations of Cd is 0.0115mg/m$^{3}$ in the porcelain part, 0.0090mg/m$^{3}$ in the polishing part, that of Ni is 0.2864mg/m$^{3}$ in the porcelain part, 0.3188mg/m$^{3}$ in the polishing part, that of Cr is 0.0448mg/m$^{3}$ in the porcelain part, 0.1032mg/m$^{3}$ in the polishing part. 2. The concentrations of Cd, Ni and Cr in the technicians urine are 3.06 $\mu$g/l, 44.55 $\mu$g/l and 14.58 $\mu$g/l. Those of students, urine as the control group are 1.93 $\mu$g/l, 19.05 $\mu$g/l and 7.48 $\mu$g/l. There is significant difference between experimental group and control group (P < 0.01). 3. Watching for age and working place, 31-40 years age group reveals the highest group in the concentrations of Cd. Over 41 year age group represents the highest group in the concentrations of Ni and Cr (P < 0.01) The concentration of Cd turns up the highest in the partial part and that of Ni and Cr appears the highest in the polishing part (P < 0.01). Looking into working age, over 7 year group is the highest group in the concentrations of all investigated (P < 0.05).

• Journal of the Mineralogical Society of Korea
• /
• v.23 no.3
• /
• pp.227-234
• /
• 2010

We investigated the effect of dry grinding of laterite on the extraction of nickel and cobalt. The major chemical compositions of the sample for this work were $SiO_2$, $Fe_2O_3$ and MgO. The sample contained 0.81% Ni and 0.02% Co. The major minerals of the sample were lizardite and quartz with minor amounts of forsterite and enstatite. The mean particle size, specific surface area and density of the ground sample decreased with increasing grinding time, while the amorphization of lizardite increased as identified by XRD analysis. The grinding enabled the extraction ratio of Ni and Co to increase by the breakdown of Mg-OH bonding in the lizardite structure. However, physical properties of quartz were not changed by grinding. The extraction ratio of Ni and Co increased with increasing grinding time. Approximately 80% of Ni and Co were extracted regardless of the kind of acid solutions when the sample was ground for 60 minutes.

• Resources Recycling
• /
• v.9 no.3
• /
• pp.3-12
• /
• 2000

A Study on the cementation for the recovery of Cu, Ni and Co with Mn metallic powders in leaching solution from the manganese nodule that have removed Fe ions was studied. The results showed that the recovery efficiencies of metal ions with Mn powders increased when the temperature, pH and the concentration of chloride ions were increased in mixed solution. And the recovery efficiencies of Cu was 98% and not changed with the addition amounts of Mn powders but, in case of Co and Ni, the recovery efficiencies were increased with the addition amounts. The particle size of precipitate was about $5\mu\textrm{m}$. From the results of experiment we proposed the two-step cementation process for the recovery of Cu, Ni and Co with Mn powders.

• Journal of the Korean Magnetics Society
• /
• v.9 no.3
• /
• pp.159-165
• /
• 1999

Structural, magnetic and magnetoresistance behavior of NiFe/Ag multilayers prepared by a magnetron sputter under an Ar and $Ar/H_2$ atmosphere was studied. It was difficult to make a uniform multilayer by using an Ar atmosphere. However, the uniform multilayers could be fabricated by using an $Ar/H_2$ atmosphere. This was thought to be due to decrease in the energy of the sputtered atom and Ar content of the film. Typical magnetoresistance behavior of the discontinuous NiFe/Ag multilayers appeared when the uniform multilayer was formed and annealed. Substrate temperature did not improve the uniformity of the multilayers. Above 20$0^{\circ}C$ of the substrate temperature, the films were almost formed into granular alloys rather than multilayers.

• Economic and Environmental Geology
• /
• v.40 no.5
• /
• pp.587-604
• /
• 2007

In order to investigate the vertical variations and speciations of trace elements, and their correlations in Hoidong reservoir, sediment cores (21-41 cm below surface) and interstitial water samples were collected from five sampling locations. The total average concentrations of trace metals in sediment core samples were $232{\pm}30.8mg/kg$ for Zn, $119{\pm}272mg/kg$ for Cu, $58.4{\pm}4.1mg/kg$ for Pb, $15.7{\pm}3.3mg/kg$ for Ni and $1.6{\pm}0.3mg/kg$ for Cd. The total concentrations of trace metals in core sediments generally decreased toward the center of the Hoidong reservoir. The total concentrations of Mn, Pb and Zn decreased with depth for all the sample locations, while Cu and Fe concentrations increased. The trace metal concentrations of interstitial water sample were in the order of Fe>Mn>Cu>Zn, but Cd, Ni and Pb were not detected. The concentrations of Zn, Cu, Fe and Mn in the interstitial water samples showed a tendency of increasing toward the bottom of the core, suggesting a possible upward diffusion. This migration of trace metals may lead to their transfer to the sediment-water interface. These trace elements would be subsequently fixed onto amorphous Fe and Mn-oxides and carbonates in the topmost layer of sediment. Based on the $K_D$ values, the relative mobilities of the studied metals were in the order of Mn>Cu>Zn>Fe. Geochemical partitioning confirmed that surface enrichment by trace metals mainly resulted from a progressive increase of the concentrations in the fractions II and III. Copper, Fe, Mn and Zn concentrations of interstitial water were closely correlated with their exchangeable fractions of sediments.

• Korean Journal of Environmental Agriculture
• /
• v.16 no.4
• /
• pp.399-403
• /
• 1997

Changes of nutrient material and natural supplies by sediment of irrigation water into 1.0ha of paddy field during the rice cultivation were investigated. TSS of the sediment contained irrigation water ranged 52.9${\sim}$125.6mg/L and content of organic matter showed 1.89${\sim}$2.33%. Content of T-N, $NH_4-N$ and $NO_3-N$ were 623.5${\sim}$1775.2, 22.9${\sim}$75.8 and 10.2${\sim}$72.1mg/kg respectively. Content of T-P and ortho-P were 186.7${\sim}$375.7 and 12.4${\sim}$38.9mg/kg respectively. The content of exchangeable canons, $Ca^{++},\;Mg^{++}\;Na^+\;and\;K^+$ were 435.3${\sim}$737.5, 127.3${\sim}$204.2, 36.6${\sim}$94.9 and 105.6${\sim}$232.9mg/kg respectively. Total content of heavy metals were 13.4 of Pb, 0.6 of Cd, 8.2 of Ni, 12.1 of Cu, 29.8 of Zn and 19.7mg/kg of Cr. During the period of rice cultivation, when supplied 4,250m^3 of an irrigation water into 1.0ha of paddy field, natural supplied 346.01kg of sediment, 7.11kg of organic matter, 0.50kg of T-N, 0.02㎏ of NH_4-N, 0.01kg of NO_3-N, 0.08kg of T-P and 0.01㎏ of Ortho-P. Also exchangeable $Ca^{++},\;Mg^{++}\;Na^+\;and\;K^+$ were supplied 0.21, 0.06, 0.02 and 0.06kg respectively. Loaded of the total heavy metal showed natural background level.

• Journal of Korean Society of Environmental Engineers
• /
• v.37 no.9
• /
• pp.499-504
• /
• 2015

The composite anodes of expanded graphite (EG) and multiwall carbon nanotube (MWCNT) for microbial fuel cells were fabricated by using coal tar pitch (CTP) binder containing nickel (Ni), and the effect of the anodes with the binders on the performance of the MFCs were examined in a batch reactor. During the start-up of the MFCs, quick increase in voltage was observed after a short lag phase time, indicating that the CTP binder is biocompatible. The biomass attatched on the anode surface was more at higher Ni content in the binder, as well as at smaller amount of CTP binder for the fabrication of the anode. The internal resistance of the MFC was smaller for the anode with more biomass. Based on the results, the ideal combination of CTP and Ni for the CTP binder for anode was 2 g and 0.2 g, respectively. The maximum power density was $731.8mW/m^2$, which was higher 23.7% than the anode with Nafion binder as control. The CTP binder containing Ni for the fabrication of anode is a good alternative in terms of performance and economics of MFCs.

• Korean Journal of Materials Research
• /
• v.8 no.3
• /
• pp.206-213
• /
• 1998

Cu, Ni, and Mo were ion-diffused into the pure steel powder in the aqueous solution of $(CuNO_3)_2$, $Ni(NO_3)_2)_2$, and $(NH_4)_6Mo_7O_{24}$, to form partial diffusion bond prealloyed steel powder. The mechanical properties, and compacting and sintering characteristics were investigated as a function of Cu. Ni and Mo contents. The results of the this research, it was found that the smallest change of size was observed, and the good degree of hardness and tensile strength was observed when 1.50wt%Cu, 1.75wt%Ni and 0.50wt%Mo was added each other. The powder metallurgy characteristics of partial diffusion bond prealloyed steel powder containing 1.50wt% of Cu, 1.75wt% of Ni and 0.5wt% of Mo were compared to those of distalloy $AB\textregistered$ which was manufactured in Hogani Corporation of Sweden. Partial diffusion bond prealloyed steel powder of this study had good degree of hardness and density, and its dimensional stability was same to that of pure steel powder. Under the same sintering density and temperature, the tensile strength of the ion powder from this research was $15~20Kg/\textrm{mm}^2$ larger than that of distalloy AB'. also the hardness was larger in the magnitude of Hv20-30. When the powder metallurgy heat-treated, hardness and tensile strength were substantially increased.