• Current Photovoltaic Research
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• v.5 no.3
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• pp.83-88
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• 2017

The growth of intermetallic compounds is an important factor in the reliability of solar cells. Especially, the temperature change in the soldering process greatly affects the thickness of the intermetallic compound layer. In this study, we investigated the intermetallic compound growth by Sn-diffusion in solder joints of solar cells. The thickness of the intermetallic compound layer was analyzed by IR lamp power and hot plate temperature control, and the correlation between the intermetallic compound layer and the adhesive strength was confirmed by a $90^{\circ}$ peel test. In order to investigate the growth of the intermetallic compound layer during isothermal aging, the growth of the intermetallic compound layer was analyzed at $85^{\circ}C$ and 85% for 500 h. In addition, the activation energy of Sn was calculated. The diffusion coefficient of the intermetallic compound layer was simulated and compared with experimental results to predict the long-term reliability.

• Journal of Powder Materials
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• v.11 no.2
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• pp.105-110
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• 2004

In this study the possibility to obtain a homogeneous mixture and to produce solid solutions and intermetallic compounds of Fe and Al nano particles by simultaneous pulsed wire evaporation (S-PWE) have been investigated. The Fe and Al wires with 0.45 mm in diameter and 35 mm in length were continuously co-fed by a special mechanism to the explosion chamber and simultaneously exploded. The characteristics, e.g., phase composition, particle shape, and specific surface area of Fe-Al nano powders have been analyzed. The synthesized powders, beside for Al and $\alpha$-Fe, contain significant amount of a high-temperature phase of $\gamma$-Fe, Fe Al and traces of other intermetallics. The phase composition of powders could be changed over broad limits by varying initial explosion conditions, e.g. wire distance, input energy, for parallel wires of different metals. The yield of the nano powder is as large as 40 wt ％ and the powder may include up to 46 wt % FeAl as an intermetallic compound.

• Journal of the Microelectronics and Packaging Society
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• v.17 no.3
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• pp.59-63
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• 2010

Immersion Sn plating was produced on Cu foil by distributing nano-sized diamonds (ND). The ND distributed on the coating surface broke the continuity of Sn-oxide layer, therefore leading to penetrate the molten solder through the oxide and retarding the wettability degradation during a reflow process. Furthermore, the ND in the Sn coating played a role of diffusion barrier for Sn atoms and decreased the growth rate of intermetallic compound ($Cu_6Sn_5$) layer during the solid-state aging. The study confirmed the importance of ND to improve the wettability and reliability of the Sn plating. Complete dispersion of the ND within the immersion Sn plating needs to be further developed for the electronic packaging applications.

• Journal of Welding and Joining
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• v.32 no.3
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• pp.43-52
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• 2014

Recent developing tendency of thermal spray for green automotive industry are studied by searching of NDSL, KIPRIS, ScienceDirect and so on. Spraying techniques such as plasma spray, microwave treatment, dry-ice blasting, HVOF thermal spray, cold spraying, aerosol deposition are introduced, further more spraying materials such as nano particles, intermetallic compound, TiAlN, TiC, Si-Al alloys are investigated.

• Korean Journal of Materials Research
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• v.18 no.3
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• pp.153-158
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• 2008

Fe-aluminides have the potential to replace many types of stainless steels that are currently used in structural applications. Once commercialized, it is expected that they will be twice as strong as stainless steels with higher corrosion resistance at high temperatures, while their average production cost will be approximately 10% of that of stainless steels. Self-propagating, high-temperature Synthesis (SHS) has been used to produce intermetallic and ceramic compounds from reactions between elemental constituents. The driving force for the SHS is the high thermodynamic stability during the formation of the intermetallic compound. Therefore, the advantages of the SHS method include a higher purity of the products, low energy requirements and the relative simplicity of the process. In this work, a Fe-aluminide intermetallic compound was formed from high-purity elemental Fe and Al foils via a SHS reaction in a hot press. The formation of iron aluminides at the interface between the Fe and Al foil was observed to be controlled by the temperature, pressure and heating rate. Particularly, the heating rate plays the most important role in the formation of the intermetallic compound during the SHS reaction. According to a DSC analysis, a SHS reaction appeared at two different temperatures below and above the metaling point of Al. It was also observed that the SHS reaction temperatures increased as the heating rate increased. A fully dense, well-bonded intermetallic composite sheet with a thickness of $700\;{\mu}m$ was formed by a heat treatment at $665^{\circ}C$ for 15 hours after a SHS reaction of alternatively layered 10 Fe and 9 Al foils. The phases and microstructures of the intermetallic composite sheets were confirmed by EPMA and XRD analyses.

• Journal of Welding and Joining
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• v.25 no.3
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• pp.51-56
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• 2007

A $CO_2$ laser overlay was conducted by using a Fe-based powder on the AC2B aluminum substrate. Cracks and intermetallic compounds (IMC) were observed inconsistently along the interface between the overlay and post-molten layer. A scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS) detected some Fe-rich IMC ($Fe_3Al$, FeAl) as well as the brittle Al-rich IMC ($Fe_2Al_5,\;FeAl_3$). Micro vickers hardness proved the formation of Al-rich IMC ($FeAl_3$) along the interface by showing HV0.1 $800{\sim}900$. Furthermore, nano indentation was successfully applied to investigate the behavior of IMC more precisely than the micro vickers hardness.

• Korean Journal of Materials Research
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• v.14 no.10
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• pp.688-695
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• 2004

The capacitor contact barrier(CCB) layers have been introduced in the FeRAM integration to prevent the Pt/Al reaction during the back-end processes. Therefore, the interdiffusion and intermetallic formation in $Pt(1500{\AA})/Al(3000{\AA})$ film stacks were investigated over the annealing temperature range of $100\sim500^{\circ}C$. The interdiffusion in Pt/Al interface started at $300^{\circ}C$ and the stack was completlely intermixed after annealing over $400^{\circ}C$ in nitrogen ambient for 1 hour. Both XRD and SBM analyses revealed that the Pt/Al interdiffusion formed a single phase of $RtAl_2$ intermetallic compound. On the other hand, in the presence of TiN($1000{\AA}$) barrier layer at the Pt/Al interface, the intermetallic formation was completely suppressed even after the annealing at $500^{\circ}C$. These were in good agreement with the predicted effect of the TiN diffusion barrier layer. But the conventional TiN CCB layer could not perfectly block the Pt/Al reaction during the back-end processes of the FeRAM integration with the maximum annealing temperature of $420^{\circ}C$. The difference in the TiN barrier properties could be explained by the voids generated on the Pt electrode surface during the integration. The voids were acted as the starting point of the Pt/Al reaction in real FeRAM structure.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.2
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• pp.1-8
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• 2018

In the soldering industry, a variety of lead-free solders have been developed as a part of restricting lead in electronic packaging. Sn-Ag-Cu (SAC) lead-free solder is regarded as one of the most superior candidates, owing to its low melting point and high solderability as well as the mechanical property. On the other hand, the mechanical property of SAC solder is directly influenced by intermetallic compounds (IMCs) in the solder joint. Although IMCs in SAC solder play an important role in bonding solder joints and impart strength to the surrounding solder matrix, a large amount of IMCs may cause poor strength, due to their brittle nature. In other words, the mechanical properties of SAC solder are of some concern because of the formation of large and brittle IMCs. As the IMCs grow, they may cause poor device performance, resulting in the failure of the electronic device. Therefore, new solder technologies which can control the IMC growth are necessary to address these issues satisfactorily. There are an advanced nanotechnology for microstructural refinement that lead to improve mechanical properties of solder alloys with nanoparticle additions, which are defined as nano-reinforced solders. These nano-reinforced solders increase the mechanical strength of the solder due to the dispersion hardening as well as solderability of the solder. This paper introduces the nano-reinforced solders, including its principles, types, and various properties.

• Journal of Korea Foundry Society
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• v.30 no.6
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• pp.241-246
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• 2010

The viscosity of foam metal is necessary to get the pores, but it is difficult to manufacture net-shape foam, because the fluidity decreases by increasing viscosity. In this study, the A356 alloy which has good fluidity and less defect was selected and fabricated to foam metal. To understand about effect of thickening agent on foaming and mechanical properties, quantity of thickening agent was changed. The pore size, porosity and distribution of foam metal were measured by i-solution program. And compression test were performed by UTM. In case of 3.0wt% Ca in thickening agent, it is found that most of foam consist of homogeneous shape, and the growth height had the highest value of 204 mm in the all fabricated foams. The porosity was 93% and compressive strength was 3.1 MPa. In the microstructure, the $Al_2Si_2Ca$ intermetallic compound and Ti were observed. The vickers hardness value rose with increasing viscosity value.

• Journal of the Korean Ceramic Society
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• v.40 no.1
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• pp.87-92
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• 2003

$Ti_3AlC_2$was synthesized from TiCx and Al powder as a starting materials at the temperature range between$800^{circ}C;and;1500^{\circ}C$. The vacuum sintering and hot pressing methods were imployed to synthesize$Ti_3AlC_2$. The high purity$Ti_3AlC_2$was synthesized using TiCx and Al powder as starting materials without formation of Ti-Al intermetallic compound and Al-C compound.$Ti_2$AlC and$Ti_3AlC_2$were preferentially synthesized at$800^{\circ}C$and above$1200^{\circ}C$, respectively.$Ti_2$AlC formed at low temperature was transformed to$Ti_3AlC_2$by further reaction with TiC. In this study, the synthesis mechanism for$Ti_3AlC_2$was proposed. The synthesized$Ti_3AlC_2$showed the nano laminating structure consisting of$Ti_3AlC_2$crystal with the thickness of 45~120 nm.