• Journal of radiological science and technology
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• v.26 no.1
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• pp.45-50
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• 2003

In this work, we characterized the shieldability and lightweight of radiation protective aprons which were consisted of various metal(Pb, Sn, Ni, Ti and Cu) by measuring the x-ray dose transmitted through the filters. The transmitted ratio and lead equivalent of various metal were obtained by linear interpolation and the lead equivalent of double layered filters contained Pb layer was determined. The transmitted ratio of the apron(0.25 mmPb) specified in KS B 0845 was 5.2%. The transmitted ratio of the filters at the thickness of 0.6 mm was decreased in the other of Ni(32.60%), Ti(17.75%), Cu(13.25%) and Sn(3.84%). From the results of experimental evaluation for combined filter of Pb and Sn, it was founded that in the case of the first Sn layer, the lead equivalent was higher than that of the first Pb layer. The lead equivalent corresponding to apron of 0.25 mmPb was obtained in the double layered filters of Sn(0.19 mm) - Pb(0.1 mm) and Pb(0.1 mm) - Sn(0.37 mm). Thus, the Sn-Pb filter had the lower weight about 13% than apron of 0.25 mmPb.

• Korean Journal of Materials Research
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• v.10 no.12
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• pp.799-806
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• 2000

Cu$_{6}$Sn$_{5}$-dispersed 63Sn-37Pb solder bumps of 760$\mu\textrm{m}$ size were fabricated on Au(0.5$\mu\textrm{m}$)/Ni(5$\mu\textrm{m}$)/Cu(27$\pm$20$\mu\textrm{m}$) BGA substrates by screen printing process, and their shear strength were characterized with variations of dwell time at reflow peak temperature and aging time at 15$0^{\circ}C$ . With dwell time of 30 seconds at reflow peak temperature, the solder bumps with Cu$_{6}$Sn$_{5}$ dispersion exhibited higher shear strength than the value of the 63Sn-37Pb solder bump. With increasing the dwell time longer than 60 seconds, however the shear strength of the Cu$_{6}$Sn$_{5}$-dispersed solder bumps became lower than that the 63Sn-37Pb solder bumps. The failure surface of the solder bumps could be divided into two legions of slow crack propagation and critical crack propagation. The shear strength of the solder bumps was inversely proportional to the slow crack propagation length, regardless of the dwell time at peak temperature, aging time at 150 $^{\circ}C$ and the volume fraction of Cu$_{6}$Sn$_{5}$ dispersion.> 5/ dispersion.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.1 s.34
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• pp.47-52
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• 2005

Worldwide movement for prohibition of Pb usage drives imminent implementation of Pb-free solders in microelectronic packaging industry. Reliability information of Pb-free solders has not been completely constructed yet. One of the potential reliability concerns of Pb-free solders is allotropic transformation of Sn known as tin pest. Volume increase during the formation of tin pest could deteriorate the reliability of solder joints. It was also reported that the addition of soluble elements (i.e. Pb, Bi, and Sb) into Sn can effectively suppress the tin pest. However, the mechanical properties of the tin pest resistant alloys have not been studied in detail. In this study, lap shear creep test was conducted with Sn and Sn-0.7Cu based solder alloys doped with minor amount of Bi or Sb. Shear strain rates of the alloy were generally higher than those of Sn-3.5Ag based alloys. Rupture strains and corresponding Monkman- Grant products were largest for Sn-0.5Bi alloy and smallest for Sn-0.7Cu-0.5Sb alloy. Rupture surface Sn-0.5Bi alloy showed highly elongated $\beta$-Sn globules necked to rupture by shear stresses, while elongation of $\beta$-Sn globules of Sn-0.7Cu-0.5Sb alloy was relatively smaller.

• Korean Journal of Materials Research
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• v.10 no.11
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• pp.770-777
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• 2000

Microstructure and mechanical properties of the $Cu_6Sn_5$-dispersed 63Sn-37Pb solder alloy, for which $Cu_6Sn_5$ powders less than $1{\mu\textrm{m}}$ size were fabricated by mechanical alloying, were characterizde and compared with those of the Cu-dispersed solder alloy. Compared to the $Cu_6Sn_5$-dispersed solder alloy, large amount of $Cu_6Sn_5$ and fast growth of $Cu_6Sn_5$ were observed in the Cu-dispersed alloy. The $Cu_6Sn_5$-dispersed solder alloy exhibited lower yield strength, but higher ultimate tensile strength than those of the Cu-dispersed alloy. With dispersion of 1~9 vol% $Cu_6Sn_5$ and Cu, the yield strength increased from 23 MPa and to 40 MPa, respectively. The ultimate tensile strength increased from 34.7 MPa to 45.3 MPa and to 43.1 MPa with dispersion of 5 vol% $Cu_6Sn_5$ and Cu, respectively.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.2 s.31
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• pp.53-58
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• 2004

To facilitate the observation of the electromigration of 63Sn-37Pb eutectic solder, strip-type samples were fabricated by solder evaporation. The electromigration test for the 63Sn-37Pb solder strip was conducted at temperatures of $80{\sim}150^{\circ}C$ and the current densities of $1{\times}10^4{\sim}1{\times}10^5\;A/cm^2$. With increasing temperature and the current density, mean-time-to-failure(MTTF) decreased due to the formation of hillock and void in the solder strip. The activation energy for the electromigration in the 63Sn-37Pb solder strip was analyzed as $0.16{\sim}0.5\;eV$ using Black's equation.

• Journal of Welding and Joining
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• v.20 no.4
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• pp.505-509
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• 2002

Pb is considered to be eliminated from solder, due to its toxicity. However, melting temperatures of most Pb-free solders are known higher than that of Sn37Pb. Therefore, there is a difficulty to apply Pb-free solders to electronic industry. Since Sn3Ag8Bi5In has relatively lower melting range as $188~200^{\circ}C$, on this study. Wettability and soldering characteristics of Sn3Ag8Bi5In solder in BGA were investigated to solve for what kind of problem. Zero cross time, wetting time, and equilibrium force of Sn3Ag8Bi5In solder for Cu and plated Cu such as Sn, Ni, and Au/Ni-plated on Cu were estimated. Plated Sn on Cu showed best wettability for zero cross time, wetting time and equilibrium farce. Shear strength of the reflowed joint with Sn3Ag8Bi5In ball in BGA was investigated. Diameter of the ball was 0.5mm, UBM(under bump metallurgy) was $Au(0.5\mu\textrm{m})Ni(5\mu\textrm{m})/Cu(18\mu\textrm{m})$ and flux was RMA type. For the reflow soldering, the peak reflow temperature was changed in the range of $220~250^{\circ}C$, and conveyor speed was 0.6m/min.. The shear strength of Sn3Ag8Bi5In ball showed similar level as those of Sn37Pb. The soldered balls are aged at $110^{\circ}C$ for 36days and their shear strengths were evaluated. The shear strength of Sn3Ag8Bi5In ball was increased from 480gf to 580gf by aging for 5 days.

• Journal of Food Hygiene and Safety
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• v.14 no.1
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• pp.115-121
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• 1999

The effect of storage temperature and time on the contents of metal (Pb, Sn and Fe), vitamin C, color and pH was studied for canned pineapple juice (PJ) and pineapple slice (PS) which were stored for 120 hours at 5 and 2$0^{\circ}C$ and analyzed at 24 hours intervals. The results are as follows; 1. The metal contents of PJ and PS were in the rank of 24<48<72<96<120 hours by storage time at 5 and 2$0^{\circ}C$. These contents were increased to 44.1%/24 hrs of Ph, 18.0%/24 hrs of Sn, 34.6%/24 hrs of Fe but decreased to 6.0%/24 hrs of vitamin C in PJ and PS during 120 hrs. Storage times were correlation to contents of metal and pH but was not correlation to vitamin C contents. These were increased to 37.7%/24 hrs of Pb, 18.8%/24 hrs of Sn, 34.6%/24 hrs of Fe, but decreased to 6.0%/24 hrs of vitamin C. 2. These were increased to 10.6% of Pb, 3.7% of Sn, 11.3% of Fe in PJ and to 33.7% of Pb, 4.8% of Sn, 37.6% of Fe in PS at 2$0^{\circ}C$ than 5$^{\circ}C$ but vitamin C contents were decreased to 8.2% in PJ and 2.7% in PS at 2$0^{\circ}C$ than 5$^{\circ}C$. This fact suggests that more attention be paid in handling canned PJ and PS after opening in order to avoid the decreasing vitamin C and the hazard from Pb, Sn, Fe. 3. Changing factors in Pb, Sn, Fe and vatiamin C content were in the rank of storage temperature$0^{\circ}C$.

• Journal of Conservation Science
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• v.35 no.5
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• pp.508-517
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• 2019

This study analyzed on alloys and by-product samples produced through the reproduction experiment of bronze mirror with geometric designs. The alloy ratio used in the first and second reproduction experiments was based on the analysis results of bronze mirror with geometric designs(Cu 61.68%, Sn 32.25%, Pb 5.46%) which is the national treasure No. 141. As a result of portable X-ray fluorescence analysis on the raw materials used in the reproduction experiment, the contents of copper raw materials were 98.85 wt% for Cu, tin raw materials were 99.03 wt% for Sn, and lead raw materials were 70.19 wt% for Pb, and 21.81 wt% for Sn. Sn and Pb were added 5 wt% more considering the evaporation amount of tin and lead during alloy melting. The result produced by the first reproduction experiment were 58.75 wt% for Cu, 36.87 wt% for Sn, 4.39 wt% for Pb, and the other result produced by the second reproduction experiment were 58.66 wt% for Cu, 35.89 wt% for Sn, and 5.50 wt% for Pb. The composition of the components was about 3.00 wt% in Cu and Sn respectively, and the microstructure was similar to the previous studies because the δ phase was observed mainly. The results of this study will be used as basic data for the materialistic characteristics of ancient bronze mirror in the future.

• Journal of the Korean institute of surface engineering
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• v.36 no.5
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• pp.386-392
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• 2003

The electroplating process for a solder bump which can be applied for a flip chip was studied. Si-wafer was used for an experimental substrate, and the substrate were coated with UBM (Under Bump Metallization) of Al(400 nm)/Cu(300 nm)Ni(400 nm)/Au(20 nm) subsequently. The compositions of the bump were Sn-Cu and eutectic Sn-Pb, and characteristics of two bumps were compared. Experimental results showed that the electroplated thickness of the solders were increased with time, and the increasing rates were TEX>$0.45 <\mu\textrm{m}$/min for the Sn-Cu and $ 0.35\mu\textrm{m}$/min for the Sn-Pb. In the case of Sn-Cu, electroplating rate increased from 0.25 to $2.7\mu\textrm{m}$/min with increasing current density from 1 to 8.5 $A/dm^2$. In the case of Sn-Pb the rate increased until the current density became $4 A/dm^2$, and after that current density the rate maintains constant value of $0.62\mu\textrm{m}$/min. The electro plated bumps were air reflowed to form spherical bumps, and their bonded shear strengths were evaluated. The shear strength reached at the reflow time of 10 sec, and the strength was of 113 gf for Sn-Cu and 120 gf for Sn-Pb.

• Journal of Welding and Joining
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• v.25 no.2
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• pp.82-88
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• 2007

Sn-3.0Ag-0.5Cu lead fee solder was generally utilized in electronics assemblies. But it is insufficient to research about activation energy(Q) that is applying to evaluate the solder joint reliability of environmental friendly electronics assemblies. Therefore this study investigated Q values which are needed to IMC formation and growth of Sn-3.0Ag-0.5Cu/Cu and Sn-40pb/Cu solder joints during aging treatment. We bonded Sn-3.0Ag-0.5Cu and Sn-40Pb solders on FR-4 PCB with Cu pad$(t=80{\mu}m)$. After reflow soldering, to observe the IMC formation and growth of the solder joints, test specimens were aged at 70, 150 and $170^{\circ}C$ for 1, 2, 5, 20, 60, 240, 960, 15840, 28800 and 43200 min, respectively. SEM and EDS were utilized to analysis the IMCS. From these results, we measured the total IMC$(Cu_6Sn_5+Cu_3Sn)$ thickness of Sn-3.0Ag-0.5Cu/Cu and Sn-40Pb/Cu interface, and then obtained Q values for the IMC$(Cu_6Sn_5,\;Cu_3Sn)$ growth of the solder joints.