11 results on '"SANG-OK HA"'
Search Results
2. Shear test parameters for brittle fracture of flip chip solder joint
- Author
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Jong-Woong Kim, Sang-Su Ha, Seung-Boo Jung, and Sang-Ok Ha
- Subjects
Materials science ,Mechanical Engineering ,Metallurgy ,Intermetallic ,Condensed Matter Physics ,Mechanics of Materials ,Soldering ,Shear strength ,General Materials Science ,Direct shear test ,Composite material ,Ternary operation ,Joint (geology) ,Brittle fracture ,Flip chip - Abstract
Compared to conventional Sn-Pb solder, ternary Pb free solder alloys are particular susceptible to brittle fracture through the formation of intermetallic compound layers. However, the conventional...
- Published
- 2011
3. Effects of Different Kinds of Underfills and Temperature–Humidity Treatments on Drop Reliability of Board-Level Packages
- Author
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Sang-Ok Ha, Bo-In Noh, Seung-Boo Jung, and Jeong-Won Yoon
- Subjects
Absorption of water ,Materials science ,Drop (liquid) ,Epoxy ,Tribology ,Condensed Matter Physics ,Drop test ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,Polypropylene glycol ,chemistry ,visual_art ,Soldering ,Materials Chemistry ,visual_art.visual_art_medium ,Electrical and Electronic Engineering ,Composite material ,Flip chip - Abstract
The hygrothermal and mechanical reliability of board-level packages with various underfills under sequential temperature and humidity (TH) testing and drop testing were investigated. Board-level packages with underfill had greater resistance to drop shock than that without underfill, indicating that underfill protects the package from failure by absorption of the applied drop shock. The underfill, which was composed of polypropylene glycol epoxy resin and silane, exhibited good reliability for drop shock because of the improved adhesion of the underfill compared with that without the polypropylene glycol epoxy resin and silane. In addition, the drop reliability of board-level packages with underfill decreased with increasing TH test duration. Adhesion between the substrate and underfill or between the solder and underfill was decreased by moisture absorption. Components positioned at the board center were more susceptible to failure by drop shock than were corner components.
- Published
- 2010
4. Effect of multiple reflows on interfacial reaction and shear strength of Sn–Ag electroplated solder bumps for flip chip package
- Author
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Jin-Kyu Jang, Jeong-Won Yoon, Hoo-Jeong Lee, Jinho Joo, Sang-Su Ha, Young Ho Kim, Sang-Ok Ha, and Seung-Boo Jung
- Subjects
Materials science ,Metallurgy ,Shear force ,Intermetallic ,Condensed Matter Physics ,Atomic and Molecular Physics, and Optics ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,Shear (sheet metal) ,Reflow soldering ,Soldering ,Shear strength ,Direct shear test ,Electrical and Electronic Engineering ,Flip chip - Abstract
The effect of displacement rate and intermetallic compound (IMC) growth on the shear strength of electroplated Sn-2.5Ag (in wt.%) flip chip solder with Cu under-bump metallization (UBM) were investigated after multiple reflows. Cu"6Sn"5 IMC was formed at the interface after one reflow. After five reflows, two different IMC layers, consisting of a scallop-shaped Cu"6Sn"5 phase and a planar Cu"3Sn phase, and their thicknesses increased with increasing reflow number up to 10. The shear strengths peaked after four reflows, and then decreased with increasing reflow number. Increasing displacement rate increased the shear force. The tendency toward brittle fracture characteristics was intensified with increasing displacement rate and reflow number.
- Published
- 2010
5. Mechanical Property Evaluation of Sn-3.0A-0.5Cu BGA Solder Joints Using High-Speed Ball Shear Test
- Author
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Jong-Woong Kim, Jin-Kyu Jang, Jeong-Won Yoon, Byung-Woo Kim, Seung-Boo Jung, Sun-Kyu Park, Sang-Su Ha, and Sang-Ok Ha
- Subjects
Materials science ,Intermetallic ,Fractography ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials ,Flexural strength ,Soldering ,Ball grid array ,Materials Chemistry ,Ball (bearing) ,Direct shear test ,Electrical and Electronic Engineering ,Composite material ,Ball shear - Abstract
The traditional ball shear test is not suitable for evaluating joint reliability under drop loading, since the applied test speeds, usually lower than 5 mm/s, are well below the impact velocity applied to the solder joint in a drop test. The present study expands recently reported research by investigating the effect of thermal aging on the joint strength and fracture mode of Sn-3.0Ag-0.5Cu ball grid arrays during high-speed shear testing, with a shear height of 50 μm and a shear speed ranging from 0.01 m/s to 3 m/s. The test specimens were aged at 393 K for 1000 h. After reflow, a (Ni,Cu)3Sn4 intermetallic compound (IMC) layer was observed at the solder/Ni-P interface and the thickness of the IMC layer was increased through the aging process. The shear strength increased with increasing shear speed. The fracture surface of the solder joints showed three different fracture modes according to the shear speed and aging time. The fracture mode changed from ductile fracture to brittle fracture with increasing shear speed.
- Published
- 2009
6. Solder joint reliability in flip chip package with surface treatment of ENIG under thermal shock test
- Author
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Dae-Gon Kim, Sang-Su Ha, Jeong-Won Yoon, Jong-Woong Kim, Min-Kwan Ko, Sang-Ok Ha, Tae-Hwan Hong, Seung-Boo Jung, and Sung-Jin Kim
- Subjects
Thermal shock ,Materials science ,Metals and Alloys ,Condensed Matter Physics ,Chip ,Finite element method ,Reliability (semiconductor) ,Mechanics of Materials ,Soldering ,Solid mechanics ,Materials Chemistry ,Forensic engineering ,Composite material ,Joint (geology) ,Flip chip - Abstract
This study investigated the microstructural evolution and evaluated the thermo-mechanical reliability of a Sn-3.0Ag-0.5Cu (in wt.%) flip chip package during a thermal shock test. The reliability of the flip chip bonded packages was evaluated by means of the thermal shock in the temperature range of 233 K to 398 K. After 250 thermal shock cycles, cracks finally occurred at the corner solder bump joint on the chip side interfacial regions. In that, the crack initiated at the solder region near the intermetallic compound (IMC) layers. For the interpretation of the failure mechanism of the package, finite element analyses were conducted. From the finite element analysis or computational simulation result, the distribution of the plastic work in the corner solder bump was found to be most considerable. This means that the corner solder bump has the highest potential for first crack initiation and growth, because the thermo-mechanical failure of the solder joints is mainly caused by the accumulation of the plastic work. This matched well with the experimental results.
- Published
- 2009
7. FAILURE BEHAVIORS OF FLIP CHIP SOLDER JOINTS UNDER VARIOUS LOADING CONDITIONS OF HIGH-SPEED SHEAR TEST
- Author
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Jong-Woong Kim, Sang-Ok Ha, Jong-Bum Lee, Jin-Kyu Jang, Sang-Su Ha, and Seung-Boo Jung
- Subjects
Simple shear ,Shear rate ,Materials science ,Shear force ,Forensic engineering ,Shear stress ,Shear strength ,Statistical and Nonlinear Physics ,Direct shear test ,Composite material ,Condensed Matter Physics ,Flip chip ,Stress concentration - Abstract
The failure behaviors of flip chip solder joints under various loading conditions of the high-speed shear test (H-SST) were investigated with an experimental and non-linear 3-dimensional finite element modeling study. The solder composition used in this study was Sn -3.0 Ag -0.5 Cu ( in wt .%). The shear forces were far greater by H-SST than by low-speed shear test (L-SST). The shear force further increased with increasing shear speed, mainly due to the high strain-rate sensitivity of the solder alloy. Brittle interfacial fractures were more easily achieved by H-SST, especially at the higher shear speed. This was discussed in terms of the relationship between the strain-rate and work-hardening effect and the resulting stress concentration at the interfacial regions
- Published
- 2009
8. Electromigration Behavior in Sn-37Pb and Sn-3.0Ag-0.5Cu Flip-Chip Solder Joints under High Current Density
- Author
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Jong-Woong Kim, Jeong-Won Yoon, Seung-Boo Jung, Sang-Su Ha, and Sang-Ok Ha
- Subjects
Void (astronomy) ,Materials science ,Solid-state physics ,Metallurgy ,Condensed Matter Physics ,Chip ,Electromigration ,Cathode ,Electronic, Optical and Magnetic Materials ,law.invention ,law ,Soldering ,Materials Chemistry ,Electrical and Electronic Engineering ,Composite material ,Current density ,Flip chip - Abstract
The electromigration of conventional Sn-37Pb and Pb-free Sn-3.0Ag-0.5Cu (in wt.%) solder bumps was investigated with a high current density of 2.5 × 104 A/cm2 at 423 K using flip-chip specimens comprised of an upper Si chip and a lower bismaleimide triazine (BT) substrate. Electromigration failure of the Sn-37Pb and Sn-3.0Ag-0.5Cu solder bumps occurred with complete consumption of electroless Ni immersion Au (ENIG) underbump metallization (UBM) and void formation at the cathode side of the solder bump. Finite element analysis and computational simulations indicated high current crowding of electrons in the patterned Cu on the Si chip side, whereas the solder bumps and Cu line of the BT substrate had a relatively low density of flowing electrons. These findings were confirmed by the experimental results. The electromigration reliability of the Sn-3.0Ag-0.5Cu solder joint was superior to that of Sn-37Pb.
- Published
- 2008
9. Meteorology influencing springtime air quality, pollution transport, and visibility in Korea
- Author
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David A. Peterson, Edward J. Hyer, Sang-Ok Han, James H. Crawford, Rokjin J. Park, Robert Holz, Ralph E. Kuehn, Edwin Eloranta, Christoph Knote, Carolyn E. Jordan, and Barry L. Lefer
- Subjects
air quality ,pollution ,meteorology ,visibility ,pollution transport ,transboundary pollution ,korus- aq ,Environmental sciences ,GE1-350 - Abstract
In an environment with many local, remote, persistent, and episodic sources of pollution, meteorology is the primary factor that drives periods of unhealthy air quality and reduced visibility. The 2016 Korea-United States Air Quality (KORUS-AQ) field study provides a unique opportunity to examine the impact of meteorology on the relative influence of local and transboundary pollution. Much of the KORUS-AQ campaign can be grouped into four distinct research periods based on observed synoptic meteorology, including a period of complex aerosol vertical profiles driven by dynamic meteorology, stagnation under a persistent anticyclone, low-level transport and haze development, and a blocking pattern. These episodes are examined using a diverse archive of ground, airborne, and satellite data. While frontal boundaries are recognized as the primary mechanism driving pollution transport in eastern Asia, results show that they are not always related to sustained periods of hazardous air quality and reduced visibility at the surface. Significant long-range transport of pollution and dust was constrained to a few short events, suggesting that the majority of pollutants sampled during KORUS-AQ originated from local sources. A severe regional pollution episode is examined in detail, featuring dense haze and significant secondary particle formation within a shallow moist boundary layer. Observations during KORUS-AQ also highlight a rapid, 40 ppbv increase in ozone pollution as a strong sea breeze front traversed the Seoul Metropolitan Area. Representativeness of meteorology and pollution conditions measured by KORUS-AQ is considered by comparison with climatology. This analysis is an essential step toward improved local and regional forecasting of air quality and visibility.
- Published
- 2019
- Full Text
- View/download PDF
10. Mechanical Property Evaluation of Sn-3.0A-0.5Cu BGA Solder Joints Using High-Speed Ball Shear Test.
- Author
-
Sang-Su Ha, Jin-Kyu Jang, Sang-Ok Ha, Jong-Woong Kim, Jeong-Won Yoon, Byung-Woo Kim, Sun-Kyu Park, and Seung-Boo Jung
- Subjects
SOLDER & soldering ,BALL grid array technology ,ELECTRONIC packaging ,INTERMETALLIC compounds ,JOINTS (Engineering) - Abstract
The traditional ball shear test is not suitable for evaluating joint reliability under drop loading, since the applied test speeds, usually lower than 5 mm/s, are well below the impact velocity applied to the solder joint in a drop test. The present study expands recently reported research by investigating the effect of thermal aging on the joint strength and fracture mode of Sn-3.0Ag-0.5Cu ball grid arrays during high-speed shear testing, with a shear height of 50 μm and a shear speed ranging from 0.01 m/s to 3 m/s. The test specimens were aged at 393 K for 1000 h. After reflow, a (Ni,Cu)
3 Sn4 intermetallic compound (IMC) layer was observed at the solder/Ni-P interface and the thickness of the IMC layer was increased through the aging process. The shear strength increased with increasing shear speed. The fracture surface of the solder joints showed three different fracture modes according to the shear speed and aging time. The fracture mode changed from ductile fracture to brittle fracture with increasing shear speed. [ABSTRACT FROM AUTHOR]- Published
- 2009
- Full Text
- View/download PDF
11. FAILURE BEHAVIORS OF FLIP CHIP SOLDER JOINTS UNDER VARIOUS LOADING CONDITIONS OF HIGH-SPEED SHEAR TEST.
- Author
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SANG-SU HA, SANG-OK HA, JIN-KYU JANG, JONG-WOONG KIM, JONG-BUM LEE, and SEUNG-BOO JUNG
- Subjects
- *
SOLDER & soldering , *SEALING (Technology) , *STRAINS & stresses (Mechanics) , *STRESS concentration , *FINITE element method - Abstract
The failure behaviors of flip chip solder joints under various loading conditions of the high-speed shear test (H-SST) were investigated with an experimental and non-linear 3-dimensional finite element modeling study. The solder composition used in this study was Sn-3.0Ag-0.5Cu (in wt.%). The shear forces were far greater by H-SST than by low-speed shear test (L-SST). The shear force further increased with increasing shear speed, mainly due to the high strain-rate sensitivity of the solder alloy. Brittle interfacial fractures were more easily achieved by H-SST, especially at the higher shear speed. This was discussed in terms of the relationship between the strain-rate and work-hardening effect and the resulting stress concentration at the interfacial regions [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF
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