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- 저자 : 洪元植 (검색결과 452 건)
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洪元植,李綿浚 中央醫學社 1974 中央醫學 Vol.26 No.5
1) 靈樞 81篇中 問答體가 아닌 篇은 3篇 7, 9, 13, 20, 21, 22, 23, 24, 25, 26, 77篇으로 12篇이다. 2) 質問은 409回로서 黃帝 386回, 雷公 23回이다. 3) 答은 409回로서 岐伯 294回, 伯高 43回, 少兪 32回, 黃帝 23回, 少師 17回이다. 4) 其他 17回는 文章끝에 帝日善하고 마친 1回와 問答이 아니고 講한 것이 黃帝 5回, 岐伯 2回 그리고 9回는 黃帝가 감탄하면서 스스로 말한 경우이다. 5) 靈樞의 問答에 참여한 사람은 黃帝, 岐伯, 伯高, 少兪, 雷公, 少師의 6人이다.
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PZT 세라믹 레조네이터 무연솔더 접합부의 열-기계적 피로 가속수명
홍원식,박노창,오철민,Hong, Won-Sik,Park, No-Chang,Oh, Chul-Min 한국재료학회 2009 한국재료학회지 Vol.19 No.6
In this study, we optimized Pb-free Sn/Ni plating thickness and conditions were optimized to counteract the environmental regulations, such as RoHS and ELV(End-of Life Vehicles). The $B_{10}$ life verification method was also suggested to have been successful when used with the accelerated life test(ALT) for assessing Pb-free solder joint life of piezoelectric (PZT) ceramic resonator. In order to evaluate the solder joint life, a modified Norris-Landzberg equation and a Coffin-Manson equation were utilized. Test vehicles that were composed of 2520 PZT ceramic resonator on FR-4 PCB with Sn-3.0Ag-0.5Cu for ALT were manufactured as well. Thermal shock test was conducted with 1,500 cycles from $(-40{\pm}2)^{\circ}C$ to $(120{\pm}2)^{\circ}C$, and 30 minutes dwell time at each temperature, respectively. It was discovered that the thermal shock test is a very useful method in introducing the CTE mismatch caused by thermo-mechanical stress at the solder joints. The resonance frequency of test components was measured and observed the microsection views were also observed to confirm the crack generation of the solder joints.
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OSP 표면처리의 열적 열화에 따른 Cu/SnAgCu 접합부의 접합강도
홍원식,정재성,오철민,Hong, Won-Sik,Jung, Jae-Seong,Oh, Chul-Min 한국마이크로전자및패키징학회 2012 마이크로전자 및 패키징학회지 Vol.19 No.1
Bonding strength of Sn-3.0Ag-0.5Cu solder joint due to degradation characteristic of OSP surface finish was investigated, compared with SnPb finish. The thickness variation and degradation mechanism of organic solderability preservative(OSP) coating were also analyzed with the number of reflow process. To analyze the degradation degree of solder joint strength, FR-4 PCB coated with OSP and SnPb were experienced preheat treatment as a function of reflow number from 1st to 6th pass, respectively. After 2012 chip resistors were soldered with Sn-3.0Ag-0.5Cu on the pre-heated PCB, the shear strength of solder joints was measured. The thickness of OSP increased with increase of the number of reflow pass by thermal degradation during the reflow process. It was also observed that the preservation effect of OSP decreased due to OSP degradation which led Cu pad oxidation. The mean shear strength of solder joints formed on the Cu pads finished with OSP and SnPb were 58.1 N and 62.2 N, respectively, through the pre-heating of 6 times. Although OSP was degraded with reflow process, the feasibility of its application was proven.
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B<sup>2</sup>it 플래시 메모리 카드용 기판의 Ag 범프/Cu 랜드 접합 계면반응
홍원식,차상석,Hong, Won-Sik,Cha, Sang-Suk 한국마이크로전자및패키징학회 2012 마이크로전자 및 패키징학회지 Vol.19 No.1
After flash memory card(FMC) was manufactured by $B^2it$ process, interfacial reaction of silver bump with thermal stress was studied. To investigate bonding reliability of Ag bump, thermal shock and thermal stress tests were conducted and then examined on the crack between Cu land and Ag bump interface. Diffusion reaction of Ag bump/Cu land interface was analyzed using SEM, EDS and FIB. The Ag-Cu alloy layer due to the interfacial reaction was formed at the Ag/Cu interface. As the diffusivity of Ag ${\rightarrow}$ Cu is faster than Cu ${\rightarrow}$ Ag, a lot of (Cu, Ag) alloy layers were observed at the Cu layer than Ag. These alloy layers contributed to increase the Cu-Ag bonding strength and its reliability.
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SnAgCu계 무연솔더의 전기화학적 반응에 따른 타펠 특성
홍원식,김광배,Hong Won Sik,Kim Kwang-Bae 한국재료학회 2005 한국재료학회지 Vol.15 No.8
Recently European Council(EU) published the RoHS(restriction of the use of certain hazardous substances in electrical and electronic equipment) which is prohibit the use of Pb, Hg, Cd, $Cr^{+6}$, PBB or PBDE in the electrical and electronic equipments. So EU member States shall ensure that, from 1 July 2006, new electrical and electronic equipment put on the market does not contain 6 hazardous substances. The one of the most important in electronics manufacturing process is soldering. Soldering process use the chemical substances which are applied in fluxing and cleaning processes and it can generate the malfunction of electronics caused by corrosion in the fields conditions. Therefore this study researched on the polarization and Tafel properties of Sn40Pb and Sn3.0Ag0.5Cu(SAC) solder based on the electrochemical theory. We prepared SnPb specimens which was aged in $150^{\circ}C,\;180^{\circ}C$ for 15 minutes ana Sn3.0Ag0.5Cu specimens that was aged in $180^{\circ}C,\;220^{\circ}C$ for 10 minutes. Experimental polarization curves were measured in distilled ionized water and $3.5 wt\%$, 1 mole NaCl electrolyte of $40^{\circ}C$, pH 7.5. Ag/AgCl and graphite were utilized by reference and counter electrode, respectively. To observe the electrochemical reaction, polarization test was conducted from -250 mV to +250 mV. From the polarization curves that were composed of anodic and cathodic curves, we obtained Tafel slop, reversible electrode potential(Ecorr) and exchange current density(Icorr). In these results, corrosion rate for two specimen were compared Sn3.0Ag0.5Cu with SnPb solders
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홍원식,김휘성,박성훈,김광배,Hong Won Sik,Kim Whee Sung,Park Sung Hun,Kim Kwang-Bae 한국재료학회 2005 한국재료학회지 Vol.15 No.8
It is inclined to increase that use of hazardous substances such as lead(Pb), mercury (Hg), cadmium(Cd) etc. are prohibited in the electronics according to environmental friendly policies of an advanced nation for protecting environment of earth. As this reasons, many researches for ensuring the reliability were proceeding in Pb free soldering process. n the flux remains on the PCB(printed circuit board) in the soldering process or the electronics exposed to corrosive environment, it becomes the reasons of breakdown or malfunction of the electronics caused by corrosion. Therefore in this studies we researched the polarization and Tafel properties of Sn40Pb and SnCu system solders based on the electrochemical theory. The experimental polarization curves were measured in distilled ionized water and 1 mole $3.5 wt\%$ NaCl electrolyte of $40^{\circ}C$, pH 7.5. Ag/AgCl and graphite were utilized by reference and counter electrodes, respectively. To observe the electrochemical reaction, polarization test was conducted from -250mV to +250mV. From the polarization curves composed of anodic and cathodic curves, we obtained Tafel slop, reversible electrode potential(Ecorr) and exchange current density((cow). In these results, we compared the corrosion rate of SnPb and SnCu solders.
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