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Wetting Balance Test를 이용한 솔더의 젖음성 분석
정도현,임동욱,백범규,임송희,윤종혁,정재필,Jung, Do-hyun,Lim, Dong-uk,Baek, Bum-gyu,Yim, Song-hee,Yoon, Jong-hyuk,Jung, Jae Pil 한국마이크로전자및패키징학회 2017 마이크로전자 및 패키징학회지 Vol.24 No.2
Recently, there has been a continuous researches on solders having sophisticated and improved performance due to demand for high-density and miniaturization of electronics, and development of solder for automotive electronics which can be used in harsh environment. When developing a new solder alloy, there is a wettability of solder on substrate for things to consider, and the wetting balance test is one of the methods for measuring that one. In this paper, the wetting balance test is introduced, and the calculus of the surface tension of solder and the contact angle between solder and substrate using wetting curve obtained is introduced too. In detail, the principle and test method of the wetting balance test, the introduction of the parameters with important meaning in the wetting curve, the method of calculating the contact angle as well as the surface tension of the solder using the shape of the solder meniscus.
정도현 ( Do Hyun Jung ) 한국산림과학회 1995 한국산림과학회지 Vol.84 No.3
This research was carried out to investigate the influences of forest road characteristics and rainfalls on the amount of erosion on the newly - constructed forest road in the Research Forests of Seoul National University located in Mt. Backwoon-san, Kwangyang. Amount of soil erosion on the newly - constructed forest road was measured for 2 years since the forest road construction. Using the stepwise multiple regression method, amount of soil erosion from cut -slopes. fill slopes, road surfaces, and side - ditches were seperately expressed as a function of statistically significant road design and rainfall factors, and multiple regression models to estimate the amount of soil erosion were significant to explain the variance in erosion by each structures. According to results of this study, amount of erosion from the newly - constructed forest road cwas estimated as much as 668.51m/㎞ for 2 years. Out of total amount of soil erosion, 21.9%(144.27m/㎞) from cut-slopes, 39.8.%(261.89m/㎞) from fill-slopes, 8.1%(53.33m/㎞) from road surfaces, and 30.2%(199.02m/㎞) from side - ditches were occurred.
Sn3.0Ag0.5Cu 솔더 볼의 고속 전단특성에 미치는 전단속도 및 UBM층의 영향
정도현 ( Do Hyun Jung ),이왕구 ( Wang Gu Lee ),정재필 ( Jae Pil Jung ) 대한금속재료학회(구 대한금속학회) 2011 대한금속·재료학회지 Vol.49 No.8
The effect of high shear speed on shear force, shear energy and fracture surface was investigated for the solder joint of a Sn-3.0Ag-0.5Cu ball. For both ENIG and OSP pads, the shear force increased with an increase in shearing speed to 0.3 m/s. However, for an ENEPIG pad, the shear force increased with an increase in shear speed to 0.6 m/s and kept almost constant afterward. The shear energy decreased with an increase in shearing speed for ENIG and OSP pads. For the ENEPIG pad, however, the shear energy almost remained constant in a shearing speed range 0.3-3.0 m/s. The fracture mode analysis revealed that the amount of brittle fracture for the ENIG and the OSP pads increased with shearing speed, and a complete brittle fracture appeared at 1.0 m/s for ENIG and 2.0 m/s for OSP. However, the ENEPIG pad showed only a ductile fracture until 0.25 m/s, and a full brittle fracture didn`t occur up to 3.0 m/s. The fracture mode matched well with the shear energy. The results from the high speed shear test of SAC305 were similar to those of SAC105.