• Transactions of Materials Processing
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• v.29 no.6
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• pp.307-315
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• 2020

The cemented carbide and stainless steel were bonded using a hot-vacuum brazing method to analyze the bonding interface. Since it is suitable for the hot vacuum brazing, nickel metal was used as a binder among the main components of the cemented carbide, and a new cemented carbide material was developed by adjusting the alloy composition. The paste, which is one of the important factors affecting the hot vacuum brazing bonding, was able to improve brazing adhesion by mixing solder as Ni powder and a binder as an organic compound at an appropriate ratio. Division of the stainless steel yielded a dense brazing result. This study elucidated the interfacial characteristics of wear-resistant parts by bonding stainless steel and cemented carbide via hot vacuum brazing.

• Journal of the Microelectronics and Packaging Society
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• v.22 no.1
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• pp.69-74
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• 2015

With difficulties during the cleaning of reflow flux residues due to the decrease of the part size and interconnection pitch in the advanced electronic devices, the need for the no-clean solder paste is increasing. In this study, an epoxy curable solder paste was made with SAC305 solder powder and the curable flux of which the main ingredient is epoxy resin and its reflow solderability, flux residue corrosivity and solder joint mechanical properties was investigated with comparison to the commercial rosin type solder paste. The fillet shape of the cured product around the reflowed solder joint revealed that the curing reaction occurred following the fluxing reaction and solder joint formation. The copper plate solderability test result also revealed that the wettability of the epoxy curable solder paste was comparable to those of the commercial rosin type solder pastes. In the highly accelerated temperature and humidity test, the cured product residue of the curable solder paste showed no corrosion of copper plate. From FT-IR analysis, it was considered to be resulted from the formation of tight bond through epoxy curing reaction. Ball shear, ball pull and die shear tests revealed that the adhesive bonding was formed with the solder surface and the increase of die shear strength of about 15~40% was achieved. It was considered that the epoxy curable solder paste could contribute to the improvement of the package reliability as well as the removal of the flux residue cleaning process.

• Applied Microscopy
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• v.45 no.2
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• pp.89-94
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• 2015

This article briefly reviews the results of recently reported research on high-temperature Pb-free solder alloys and the research trend for characterization of the interfacial reaction layer. To improve the product reliability of high-temperature Pb-free solder alloys, thorough research is necessary not only to enhance the alloy properties but also to characterize and understand the interfacial reaction occurring during and after the bonding process. Transmission electron microscopy analysis is expected to play an important role in the development of high-temperature solders by providing accurate and reliable data with a high spatial resolution and facilitating understanding of the interfacial reaction at the solder joint.

• Journal of Welding and Joining
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• v.31 no.3
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• pp.22-30
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• 2013

Due to ELV banning, automotive electronics cannot use four kinds of heavy metal element (Pb, Hg, Cd, $Cr^{6+}$) from 2016. Therefore, this study was focused on degradation characteristics of Sn-3.0Ag-0.5Cu Lead-free solder joint with OSP and ENIG finsh under various reliability assessment method, as like to thermal shock test and high temeprature/high humidity test with test duration for cabin electronics. Also, we compared bonding strength degradation to other advanced research results of electronic control unit for engine room because of difference service temperature with mount location in automotive. Whisker growth phenomenon and mitigation method which were essentially consideration items for Pb-free car electronics were examined. Conformal coating is a strong candidate for mitigating whisker growth in automotive electronics. Necessary condition to adapt Pb-free in car electronics was shown.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.231-233
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• 2005

Laser have been utilized as a heat source for the soldering of electronic components for the their capability of localized heating and faster heating rate. Laser soldering process, especially the diode laser soldering of BGA solderball was investigated. In this study, an attempt was made to investigate the possibility of laser soldering using Sn-37Pb and Sn-3Ag-0.5Cu solderball. The laser energy absorbed on the pad raised the temperature of the solderball forming a reflowed solder bump. The result were discussed based on the measurement of pull and shear strength of the bond.

• Journal of the Microelectronics and Packaging Society
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• v.21 no.4
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• pp.97-103
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• 2014

Among various lead-free solders, the Sn-58Bi solders have been considered as a highly promising lead-free solders because of its low melting temperature and high tensile strength. However, Sn-58Bi solder has the poor ductility. To enhance the mechanical property of Sn-58Bi solder, epoxy-enhanced Sn-58Bi solders have been studied. This study compared the microstructures and the mechanical properties of Sn-58Bi solder and Sn-58Bi epoxy solder with aging treatment. The solders ball were formed on the printed circuit board (PCB) with organic solderability preservative (OSP) surface finish, and then the joints were aged at 85, 95, 105 and $115^{\circ}C$ for up to 100, 300, 500 and 1000 hours. The shear test was conducted to evaluate the mechanical property of the solder joints. $Cu_6Sn_5$ intermetallic compound (IMC) layer grew with increasing aging time and temperature. The IMC layer for the Sn-58Bi epoxy solder was thicker than that for the Sn-58Bi solder. According to result of shear test, the shear strength of Sn-58Bi epoxy solder was higher than that of Sn-58Bi solder and the shear strength decreased with increasing aging time.

• Journal of the Microelectronics and Packaging Society
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• v.9 no.1
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• pp.35-41
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• 2002

Flip-chip interconnection that uses solder bump is an essential technology to improve the performance of micro-electronics which require higher working speed, higher density, and smaller size. In this paper, the shear strength of Cr/Cr-Cu/Cu UBM structure of the high-melting solder bump and that of low-melting solder bump after aging is evaluated. Observe intermetallic compound and bump joint condition at the interface between solder and UBM by SEM and TEM. And analyze the shear load concentrated to bump applying finite element analysis. As a result of experiment, the maximum shear strength of Sn-97wt%Pb which was treated 900 hrs aging has been decreased as 25% and Sn-37wt%Pb sample has been decreased as 20%. By the aging process, the growth of $Cu_6/Sn_5$ and $Cu_3Sn$ is ascertained. And the tendency of crack path movement that is interior of a solder to intermetallic compound interface is found.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.2
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• pp.1-10
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• 2022

Recently, semiconductor devices have been used in many fields owing to various applications of mobile electronics, wearable and flexible devices and substrates. During the semiconductor chip bonding process, the mismatch of coefficient of therm al expansion (CTE) between the substrate and the solder, and the excessive heat applied to the entire substrate and components affect the performance and reliability of the device. These problems can cause warpage and deterioration of long-term reliability of the electronic packages. In order to improve these issues, many studies on low-melting temperature solders, which is capable of performing a low-temperature process, have been actively conducted. Among the various low-melting temperature solders, such as Sn-Bi and Sn-In, Sn-58Bi solder is attracting attention as a promising low-temperature solder because of its advantages such as high yield strength, moderate mechanical property, and low cost. However, due to the high brittleness of Bi, improvement of the Sn-Bi solder is needed. In this review paper, recent research trends to improve the mechanical properties of Sn-Bi solder by adding trace elements or particles were introduced and compared.

• Journal of Technologic Dentistry
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• v.30 no.1
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• pp.49-55
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• 2008

In this study, to provide the fundamental data on stable connection method for successful implants prosthesis, We fabricated the solder joint of gold alloy bar specimens by gas flame soldering method and laser welding and soldering method. It compared and studied the tensile strength of two soldering method by universal testing machine. The results using universal testing machine were as follow : The mean of tensile strength of solder joint bar in gas flame soldering method specimens was 363.89 $\pm$17.62 MPa, and the mean strength of laser welding and soldering method was 125.91 $\pm$ 19.66 MPa, so gas flame soldering method was better than laser welding and soldering method and the finding better way to improve tensile strength is needed in laser welding method. On weak loading condition and the part which is needed an accuracy, laser welding method is more effective and on long-span prosthesis and frequent chewing loading part, laser welding technique is recommended first and applying additional gas flame soldering technique would be better for making much more successful prosthesis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.204-207
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• 2003

The flip chip bonding utilizing self-aligning characteristic of solder becomes mandatory to meet to tolerances for the optical device. In this paper, a parametric study of aging condition and pad size of sample was conducted. A TiW/Cu UBM structure was adopted and sample was aging treated to analyze the effect of intermetallic compound with time variation. After aging treatment, the tendency to decrease in shear strength was measured and the structure of the fine joint area was observed by using SEM, TEM and EDS. In result, the shear strength was decreased of about 20% in the $100{\mu}m$ sample at $170^{\circ}C$ aging compared with the maximum shear strength of same pad size sample. In the case of the $120^{\circ}C$ aging treatment, 17% of decrease in shear strength was measured at the $100{\mu}m$ pad size sample. Also, intremetallic compound of $Cu_6Sn_5$ and $Cu_3Sn$ were observed through the TEM measurement by using an FIB technique that is very useful to prepare TEM thin foil specimens from the solder joint interface.