• Journal of Welding and Joining
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• v.32 no.3
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• pp.60-67
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• 2014

The ability of electronic packages and assemblies to resist solder joint failure is becoming a growing concern. This paper reports on a study of high speed shear energy of Sn-4.0wt%Ag-0.5wt%Cu (SAC405) solder with different electroless Ni-P thickness, with $HNO_3$ vapor's status, and with various pre-conditions. A high speed shear testing of solder joints was conducted to find a relationship between the thickness of Ni-P deposit and the brittle fracture in electroless Ni-P deposit/SAC405 solder interconnection. A focused ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the fractured pad surface with and without $HNO_3$ vapor treatment. A scanning electron microscopy (SEM) and an energy dispersive x-ray analysis (EDS) confirmed that there were three intermetallic compound (IMC) layers at the SAC405 solder joint interface: $(Ni,Cu)_3Sn_4$ layer, $(Ni,Cu)_2SnP$ layer, and $(Ni,Sn)_3P$ layer. The high speed shear energy of SAC405 solder joint with $3{\mu}m$ Ni-P deposit was found to be lower in pre-condition level#2, compared to that of $6{\mu}m$ Ni-P deposit. Results of focused ion beam and energy dispersive x-ray analysis of the fractured pad surfaces support the suggestion that the brittle fracture of $3{\mu}m$ Ni-P deposit is the result of Ni corrosion in the pre-condition level#2 and the $HNO_3$ vapor treatment.

• Journal of environmental and Sanitary engineering
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• v.6 no.2
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• pp.109-121
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• 1991

For the analysis of mercury in blood and urine, many literatures have been reffered and many kinds of reducing agents for mercury reduction and many acids for pretreatmr are known to be varied. $So HNO_{3}$ and $H_{2}SO_{4}$ among acids and $SnCl_{2}$ and $NaBH_{4}$ as a reducing agent being chosen for the establishment of more efficient and less erroneous analysis, and comparing the absorbance by using vapor generator, the results are followings. 1. The difference of absorbance from concentration of $HNO_{3}$ and $H_{2} SO_{4}$ was not nearly found when mercury reduced by $NaBH_{4}$ after pretreatment. But for more precise analysis, conc acid treatment need to be used. 2. Higher absorbance was shown by using conto acid treatment (P<0.005) when mercury reduced by $NaBH_{4}$ after treating acid primer. And sample which has 99.5% reliability in T-test, treated by conc $H_{2}SO_{4}$(P<0.005) was shown higher absorbance than treat by CORC $HNO_{3}$. 3. The difference of absorbance was not in the slightest in higher 0.1 w/v% $NaBH_{4}$ proved by uruskal-wallis H-Test 4. Some difference of absorbance in $SnCl_{2}$(P<0.005) having 99.5% reliability was found but there was no difference in these 20 w/v% , 25 w/v% and 30 w/v% SnCl$_{2}$ by the experiment of T-test. 5. According to these test results, organic materials were much affect the absorballce when reducing mercury by using $SnCl_{2}$ rather than by $NaBH_{4}$. For bio sample which is contained various organic substances, reduclng agent $NaBH_{4}$ is a lot more efficient to reduce the error then $SnCl_{2}$. 6. analytic method for this study is as following. 7. As the recovery test was done by this, the rate of recovery was shown form 94% to 100.7% .

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.323-323
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• 2010

Saw damage of crystalline silicon wafer is unavoidable factor. Usually, alkali treatment for removing the damage has been carried out as the saw damage removal (SDR) process for priming the alkali texture. It usually takes lots of time and energy to remove the sawed damages for solar grade crystalline silicon wafers We implemented two different mixed acidic solution treatments to obtain the improved surface structure of silicon wafer without much sacrifice of the silicon wafer thickness. At the first step, the silicon wafer was dipped into the mixed acidic solution of $HF:HNO_3$=1:2 ration for polished surface and at the second step, it was dipped into the diluted mixed acidic solution of $HF:HNO_3:H_2O$=7:3:10 ratio for porous structure. This double treatment to the silicon wafer brought lower reflectance (25% to 6%) and longer carrier lifetime ($0.15\;{\mu}s$ to $0.39\;{\mu}s$) comparing to the bare poly-crystalline silicon wafer. With optimizing the concentration ratio and the dilution ratio, we can not only effectively substitute the time consuming process of SDR to some extent but also skip plasma enhanced chemical vapor deposition (PECVD) process. Moreover, to conduct alkali texture for pyramidal structure on silicon wafer surface, we can use only nitric acid rich solution of the mixed acidic solution treatment instead of implementing SDR.

• Journal of the Korean Chemical Society
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• v.41 no.8
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• pp.399-405
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• 1997

We examined the determination of trace amount of germanium in rocks and sediments by hydride vapor generation-ICP-AES. Germanium is formed volatile compounds with various types of acid reagents, but volatilizing of germanium was decreased in the presence of $H_3PO_4$. Sediments and rocks can be dissolved by mixed acids of $HF-HNO_3-H_3PO_4$ without volatilizing loss of germanium in open digestion system and it was possible to determine germanium by hydride generation-ICP-AES without further sample treatment. Detection limit of Ge is reached to 0.08 ppb under the condition of 5M $H_3PO_4$ and 1% $NaBH_4$ as a supporting acid and a reducing reagent, respectively. The measured values by hydride generation-ICP-AES agreed well with the reference values of SRMs as well as the values determined by solution nebulization-ICP-MS.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.3
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• pp.43-50
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• 2014

By the trends of electronic package to be smaller, thinner and more integrative, the reliability of interconnection between Si chip and printed circuit board is required. This paper reports on a study of high speed shear energy of Sn-4.0wt%Ag-0.5wt%Cu (SAC405) solder joints with different the thicknesses of electroless Ni-P deposit. A high speed shear testing of solder joints was conducted to find a relationship between the thickness of Ni-P deposit and the brittle fracture in electroless Ni-P deposit/SAC405 solder. A focused ion beam (FIB) was used to polish the cross sections to reveal details of the microstructure of the fractured pad surface with and without $HNO_3$ vapor treatment. The high speed shear energy of SAC405 solder joint with $1{\mu}m$ Ni-P deposit was found to be lower without $HNO_3$ vapor, compared to those of over $3{\mu}m$ Ni-P deposit. This could be due to the edge of solder resist in $1{\mu}m$ Ni-P deposit, which provides a fracture location for the weakened shear energy of solder joints and brittle fracture in high speed shear test. With $HNO_3$ vapor, the brittle fracture mode in high speed shear test decreased with increasing the thickness of Ni-P deposit. Then the roughness (Ra) of Ni-P deposits decreased with increasing its thickness. Thus, this gives the evidence that the decrease in roughness of Ni-P deposit for Eelectroless Ni/ Electroless Pd/ Immersion Au (ENEPIG) surface play a critical role for improving the robustness of SAC405 solder joint.

• Journal of Environmental Science International
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• v.17 no.5
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• pp.565-571
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• 2008

The surface properties of activated carbon modified by acids and base were studied. The influence of the surface chemistry on the adsorption of benzene and acetone vapor on modified activated carbons has been investigated The modified activated carbons were obtained by treatment with acetic acid ($CH_3COOH$), nitric acid ($HNO_3$) and sodium hydroxide (NaOH). The modified activated carbons had similar porosity but different surface chemistry and adsorption characteristics. The total surface acidity (sum of functional groups) of activated carbon (AC-AN) treated by nitric acid was 2.6 times larger than that of activated carbon (AC) before the acid treatment. Especially, carboxyl group was much developed by nitric acid treatment. The benzene equilibrium adsorption capacity of AC-AN decreased 20% more than that of AC. However, the acetone equilibrium adsorption capacity of AC-AN increased 20% more than that of AC because of the large increase of carboxyl group and acidity.

• Applied Chemistry for Engineering
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• v.24 no.1
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• pp.31-37
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• 2013

Lowering surface reflectance of Si wafers by texturization is one of the most important processes for improving the efficiency of Si solar cells. This paper presents the results on the effect of texturing using acidic solution mixtures containing the catalytic agents to moderate etching rates on the surface morphology of mc-Si wafer as well as on the performance parameters of solar cell. It was found that the treatment of contaminated crystalline silicon wafer with $HNO_3-H_2O_2-H_2O$ solution before the texturing helps the removal of organic contaminants due to its oxidizing properties and thereby allows the formation of nucleation centers for texturing. This treatment combined with the use of a catalytic agent such as phosphoric acid improved the effects of the texturing effects. This reduced the reflectance of the surface, thereby increased the short circuit current and the conversion efficiency of the solar cell. Employing this technique, we were able to fabricate mc-Si solar cell of 16.4% conversion efficiency with anti-reflective (AR) coating of silicon nitride film using plasma-enhanced chemical vapor deposition (PECVD) and Si wafers can be texturized in a short time.