Mechanical Properties Of Intermetallic Compounds Research Articles

Diffusion Growth and Mechanical Properties of Intermetallic Compounds in Mg–Pr System

Diffusion Growth and Mechanical Properties of Intermetallic Compounds in Mg–Pr System

Effect of Alloying Elements on the Stacking Fault Energy and Ductility in Mg2Si Intermetallic Compounds

Alloying elements can pronouncedly change the mechanical properties of intermetallic compounds. However, the effect mechanism of this in Mg2Si alloys is not clear yet. In this paper, systematic first-principles calculations were performed to investigate the effect of alloying elements on the ductility of Mg–Si alloys. It was found that some alloying elements such as In, Cu, Pd, etc. could improve the ductility of Mg2Si alloys. Moreover, the interatomic bonding mechanisms were analyzed through the electron localization functional. Simultaneously, the machine-learning method was employed to help identify the most important features associated with the toughening mechanisms. It shows that the ground state atomic volume (VGS) is strongly related to the stacking fault energy (γus) of Mg2Si alloys. Interestingly, the alloying elements with appropriate VGS and higher Allred–Rochow electronegativity (En) would reduce the γus in the Mg–Si–X system and yield a better ductility. This work demonstrates how a fundamental theoretical understanding at the atomic and electronic levels can rationalize the mechanical properties of Mg2Si alloys at a macroscopic scale.

Investigation of Various Bumps and Redistribution Lines to Inhibit Protected Silicon Nitride Cracks in High Pattern Density Chip Package

Mechanical stress related to chip packaging failure is the most common reliability issue in semiconductor devices, especially for high pattern density of very-large-scale integration. In this paper, redistribution lines (RDL) corresponding to gold and copper materials with capped layers (Sn-Ag and Au-Ni) were evaluated to investigate the structure dependency on the mechanical properties of intermetallic compounds, and to provide a solution to improve chip package reliability in regard to protect Si3N4 cracks. The simulation results revealed that a thicker Si3N4 film combined with the corner rounding of bump/RDL structures could mitigate Si3N4 film cracks. Voids induced by the fine pitch configuration of the top Al increase the potential risk of Si3N4 cracks during chip packaging. The reflow temperature is a major factor increasing the thermal stress in RDL patterns rather than from the bump structure. A high temperature storage test applied to the Cu pillar/Sn-Ag capping was used to investigate the intermetallic compound growth, shear strength, and hardness.

Growth and mechanical properties of intermetallic compound between solid cobalt and molten tin

Transient liquid phase (TLP) bonding has gained attention due to the advantage of producing bond that has a higher melting point than the bonding temperature. Cobalt (Co) is a potential candidate for base metal in TLP bond. This work studied the interfacial reaction in binary cobalt–tin (Co–Sn) system, growth kinetics and mechanical properties of Co–Sn intermetallic compound (IMC) for transient liquid phase (TLP) joints. Dipping method was employed for the investigation of Co–Sn IMC growth. Solid Co was immersed into molten Sn statically at varying temperatures (250–300 °C) and durations (15–60 min). The IMC formed was characterized by field emission scanning electron microscope (FESEM) coupled with energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) tests and nanoindentation. The results showed the formation of a CoSn3 layer with plate-like morphology at temperature range of 250–300 °C. The thickness of the CoSn3 layer increases with dipping temperature and duration. The growth of CoSn3 is suggested to be controlled by only diffusion reaction at 250 °C. As temperature increases to 300 °C, the growth of CoSn3 is controlled by chemical reaction. The average nanohardness and Young’s modulus of CoSn3 phase reported in this work are 4.25 ± 0.6 GPa and 98.30 ± 9.0 GPa, respectively.

Investigation of Elevated Temperature Mechanical Properties of Intermetallic Compounds in the Cu–Sn System Using Nanoindentation

Abstract In electronic packaging, most researchers are mainly focused on the mechanical properties of Cu–Sn intermetallic compounds (IMCs) at room temperature; few studies have looked into the relationship between hardness, elastic modulus, and plasticity of IMCs and elevated temperature. The hardness, elastic modulus, and plasticity of Cu6Sn5 and Cu3Sn at 25–200 °C are investigated by the nanoindentation method. The results show that the hardnesses of Cu6Sn5 and Cu3Sn obey linear attenuation law with elevated temperature. The hardness of Cu6Sn5 is more sensitive to temperature than that of Cu3Sn. This is due to the fact that the melting point of Cu6Sn5 (415 °C) is lower than that of Cu3Sn (670 °C), Cu6Sn5 has a lower normalization temperature than that of Cu3Sn. The elastic modulus of Cu6Sn5 and Cu3Sn and temperature have a parabolic law at 25–200 °C. The elastic modulus of Cu6Sn5 is more sensitive to temperature. This is attributed to the fact that the lattice structure of Cu6Sn5 is changed from hexagonal lattice to monoclinic lattice, causing its volume to expand, thereby making it more sensitive to temperature. The plasticity factors of Cu6Sn5 and Cu3Sn meet the polynomial relationship with elevated temperature. The plasticity factors of Cu6Sn5 and Cu3Sn increase with increasing temperature, which will reduce the resistance to plastic deformation. This is attributed to the fact that the vacancy generated into the material is conducive to the dislocation movement, the dislocation movement will be more active so that the plasticity factors of Cu6Sn5 and Cu3Sn gradually increase.

Nanomechanical Responses of an Intermetallic Compound Layer in Transient Liquid Phase Bonding Using Indium

Low-temperature transient liquid phase bonding (TLPB) can be achieved using indium, and the joints thus formed can withstand high temperatures. Since the joints that are formed with TLPB entirely consist of intermetallic compounds (IMCs), this study investigates the phase evolution and mechanical properties of IMCs that are obtained from isothermal reactions between In and commonly used substrate metals, Cu, Ag and Au. Using nanoindentation, the relationships between the yield strain, work hardening exponent and strain rate sensitivity of In-bearing and other frequently observed IMC phases were compared. Notably, the strain-induced precipitation of Ag3In occurred in the indent of Ag9In4.

Effect of Multi-Elements Substitution on the Mechanical Properties of Intermetallic Compound

It is well known that various elements substitute for a certain sub-lattice of intermetallic compounds. There have been various experimental investigations of the effects of substituted elements on mechanical properties, however, there are few reports describing the effects of multi-element substitution. In the present study, L12-type compounds A3B (Ni3Al and Co3(Al,W)) were selected as model compounds because their substitution behavior is well known. It was reported that various elements such as Ni, Co, Cu, Pd and Pt occupy the A-site, whereas Al, Si, Ga, Ge, Ti, V, Nb, Ta, Mo, and W occupy the B-site. These elements are expected to introduce local lattice distortion, which may affect the motion of dislocations over a wide range of temperatures. Several alloys composed of five or more elements including Ni, Co, Al, Mo, and W, were prepared using an Ar-arc melting machine and heat-treated. Several alloys were found to include an (Ni, Co)3(Al, Mo, W, …)-L12 compound as a constituent phase. The nano-hardness of these L12 phases was higher than that of the high-strength Co3(Al,W)-L12 compound, confirming that multi-element substitution is an effective way to improve the mechanical properties of an intermetallic compound without decreasing the phase stability.

Growth kinetics and grain refinement mechanisms in an undercooled melt of a CoSi intermetallic compound

The melt of a congruently melting CoSi non-stoichiometric intermetallic compound was undercooled and solidified spontaneously. The recalescence processes were recorded by a high speed camera to measure the growth velocities and the as-solidified microstructures were analyzed by electron back-scattering diffraction (EBSD) to show the grain refinement mechanisms. The monotonous increase of the growth velocity with undercooling indicates that the effect of disorder trapping is insignificant. The microstructure changes from coarse dendrites to refined equiaxed grains and then to coarse dendrites. Spontaneous grain refinement at low undercooling can be described well by both the dendrite fragmentation model and the chemical superheating model. The formation of coarse dendrites instead of refined equiaxed grains at high undercooling is ascribed to the considerable decrease of the dendrite remelting fraction. A transition from dendrites to dendritic seaweeds occurs at high undercooling. Regarding that the formation of dendritic seaweeds at high undercooling does not lead to spontaneous grain refinement, it cannot be the origin of grain refinement even in the case that dendritic seaweed splits is possible to assist the grain refinement process. The current work could be helpful for controlling the non-equilibrium microstructures and improving the mechanical properties of intermetallic compounds.

Effects of heat treatment on the intermetallic compounds and mechanical properties of the stainless steel 321–aluminum 1230 explosive-welding interface

The effects of heat treatment on the microstructure and mechanical properties of intermetallic compounds in the interface of stainless steel 321 explosively bonded to aluminum 1230 were investigated in this study. Experimental investigations were performed by optical microscopy, scanning electron microscopy, and microhardness and shear tensile strength testing. Prior to heat treatment, increasing the stand-off distance between samples from 1 to 2.5 mm caused their interface to become wavy and the thickness of intermetallic layers to increase from 3.5 to 102.3 μm. The microhardness increased from HV 766 in the sample prepared at a stand-off distance of 1 mm to HV 927 in the sample prepared at a stand-off distance of 2.5 mm; in addition, the sample strength increased from 103.2 to 214.5 MPa. Heat treatment at 450°C for 6 h increased the thickness of intermetallic compound layers to 4.4 and 118.5 μm in the samples prepared at stand-off distances of 1 and 2.5 mm, respectively. These results indicated that increasing the duration and temperature of heat treatment decreased the microhardness and strength of the interface of explosively welded stainless steel 321−Al 1230 and increased the thickness of the intermetallic region.

Influence of Nickel Thickness and Annealing Time on the Mechanical Properties of Intermetallic Compounds Formed between Cu-Sn Solder and Substrate

Influence of Nickel Thickness and Annealing Time on the Mechanical Properties of Intermetallic Compounds Formed between Cu-Sn Solder and Substrate

Influence of hot isostatic pressing on structure, phase composition and mechanical properties of intermetallic compounds on the base of Ti – Al – Nb – Mo – Cr – Zr system

Influence of hot isostatic pressing on structure, phase composition and mechanical properties of intermetallic compounds on the base of Ti – Al – Nb – Mo – Cr – Zr system

Mechanical properties of intermetallic compounds at the Sn–3.0Ag–0.5Cu/Cu joint interface using nanoindentation

Intermetallic compounds (IMCs) at the Sn–3.0Ag–0.5Cu/Cu joint interface were prepared through reflow soldering and isothermal aging in a QHL360 SMT fully automatic reflow soldering system and a high-temperature test chamber, respectively. The mechanical properties of IMCs were then studied and characterized by nanoindentation. The mechanical responses of both Cu6Sn5 and Cu3Sn (IMCs) show large dependence on the strain rate during loading. In addition, multiple pop-in events are observed in Cu6Sn5 but not evident in Cu3Sn. During loading, the contact stiffness of IMCs increases almost linearly with the indentation depth under each strain rate. In total, the hardness and elastic modulus of Cu3Sn are larger than those of Cu6Sn5, and the hardness of both Cu6Sn5 and Cu3Sn increase with increasing strain rate. During the holding stage, creep deformations of IMCs increase as loading strain rate increases. Indentation creep displacement–time curves for Cu6Sn5 and Cu3Sn can be well described by the generalized Kelvin model. The lower creep rate sensitivity exponent of Cu3Sn implies its relatively higher creep resistance.

Mechanical properties of intermetallic compounds in electrodeposited multilayered thin film at small scale by nanoindentation

Mechanical properties of intermetallic compounds (IMCs) which were formed in electrodeposited Cu/Sn and Cu/Ni/Sn multilayered thin film have been investigated. The layers of Cu, Sn and Ni were formed by electrodeposition technique using copper pyrophosphate, tin methanesulfonic and nickel Watts baths, respectively. After synthesis, samples were subjected to high temperature aging at 150°C for 168h. Two different types of intermetallics Cu3Sn and Cu6Sn5 were formed in Cu/Sn. After adding ultra-thin layer of Ni (70nm) in between Cu and Sn layers, (Cu, Ni)6Sn5 was formed after aging at similar condition to that of Cu/Sn. Tin whisker growth was not observed in both samples after preserving the samples in air for 365 days. Hardness and elastic moduli of all three different types of IMCs were measured by using a Hysitron Triboindenter 750 Ubi system. Hardness of the three IMCs Cu3Sn, Cu6Sn5, (Cu, Ni)6Sn5 and Cu were found to be 5.99, 6.61, 7.43 and 1.55GPa, respectively. The addition of Ni suppressed the growth of Cu3Sn greatly. This is expected to lead to better reliability of electronic interconnections as Cu3Sn is often associated with void formation.

Structural Size Effect on Mechanical Behavior of Intermetallic Material in Solder Joints: Experimental Investigation

The elastic and plastic mechanical properties of intermetallic compound (IMC) phases of a lead-free Sn3.5Ag/Cu-substrate soldering system are investigated in different sized joints using nano-indentation. The specimens were prepared using solid–liquid interdiffusion soldering process with joint sizes ranging from 15 to 450 μm. Solder joints were subjected to 360 °C soldering temperature for 20 min and then air cooled to room temperature to create testable IMCs thicknesses. Nano-indentation was used to extract the elastic and plastic properties of Cu6Sn5, Cu3Sn, and Ag3Sn IMCs and β-tin and copper materials. Cu–Sn IMCs formed in specimens with smaller joint size show higher elastic modulus, hardness, and yield strength and lower work hardening exponent. This was attributed to the dimensional constraints associated with decreasing joint size and the local stresses developed during fabrication in joints with different sizes. Local elastic modulus and hardness of single grains of Cu6Sn5 were obtained using a combination of nano-indentation and electron backscatter diffraction (EBSD) techniques. Grains with c-axis at a 45 deg angle with respect to the nano-indentation loading direction show higher elastic modulus (∼8.70% higher) and hardness (8.85% higher) compared to the grains that have a c-axis that is almost perpendicular to the nano-indentation loading direction.

Theoretical study of elastic, mechanical and thermodynamic properties of MgRh intermetallic compound

Abstract In the last years, Magnesium alloys are known to be of great technological importance and high scientific interest. In this work, density functional theory plane-wave pseudo potential method, with local density approximation (LDA) and generalized gradient approximation (GGA) are used to perform first-principles quantum mechanics calculations in order to investigate the structural, elastic and mechanical properties of the intermetallic compound MgRh with a CsCl-type structure. Comparison of the calculated equilibrium lattice constant and experimental data shows good agreement. The elastic constants were determined from a linear fit of the calculated stress–strain function according to Hooke's law. From the elastic constants, the bulk modulus B, shear modulus G, Young's modulus E, Poisson's ratio σ, anisotropy factor A and the ratio B/G for MgRh compound are obtained. The sound velocities and Debye temperature are also predicted from elastic constants. Finally, the linear response method has been used to calculate the thermodynamic properties. The temperature dependence of the enthalpy H, free energy F, entropy S, and heat capacity at constant volume Cv of MgRh crystal in a quasi-harmonic approximation have been obtained from phonon density of states and discussed for the first report. This is the first quantitative theoretical prediction of these properties.

Formation and Mechanical Properties of Intermetallic Compounds in Sn-Cu High-Temperature Lead-Free Solder Joints

High-temperature lead-free solders are important materials for electrical and electronic devices due to increasing legislative requirements that aim at reducing the use of traditional lead-based solders. For the successful use of lead-free solders, a comprehensive understanding of the formation and mechanical properties of Intermetallic Compounds (IMCs) that form in the vicinity of the solder-substrate interface is essential. In this work, the effect of nickel addition on the formation and mechanical properties of Cu6Sn5 IMCs in Sn-Cu high-temperature lead-free solder joints was investigated using Scanning Electron Microscopy (SEM) and nanoindentation. It was found that the nickel addition increased the elastic modulus and hardness of the (Cu, Ni)6Sn5. The relationship between the nickel content and the mechanical properties of the IMCs was also established.

Morphology and mechanical properties of intermetallic compounds in SnAgCu solder joints

This paper presents the studies to determine hardness and elastic modulus of intermetallic compound (IMC) layers in lead-free solder joints using nanoindentation technique. Two types of surface finishes, i.e., organic solderability preservative (OSP) and electrolytic Ni/Au on Cu pad, with Sn3.5Ag0.5Cu solder balls of 330 μm in diameter are studied, and the intermetallic layers are identified to be Cu 6Sn5, Cu 3Sn and (Ni y ,Cu 1− y ) 3Sn 4. The thicknesses of these IMC layers are only few microns at reflowed conditions (less than 2.3 μm). Therefore, probing mechanical properties of thinner IMCs using nanoindentation techniques poses immense difficulties and challenges. In this study, taper-mounted samples are used rather than standard cross-sectional mounted for solder joints. This taper sample gives a larger area for nanoindentation measurements. The elastic modulus and hardness of IMC layers are determined based on the parameter P/ S 2 (load/stiffness 2) as a function of the indentation depth to minimise the effects of underlying UBM or solder materials. The modulus of Cu 6Sn 5, Cu 3Sn, (Cu x ,Ni 1− x ) 6Sn 5 and (Ni y ,Cu 1− y ) 3Sn 4 layer are found to be 112.0 ± 5.1 GPa, 135.5 ± 4.3 GPa, 165.0 ± 11.3 GPa and 136.8 ± 5.8 GPa; whereas the hardness values are found to be 6.8 ± 0.4 GPa, 6.6 ± 0.5 GPa, 7.2 ± 0.9 GPa and 8.2 ± 1.0 GPa, respectively. Thus, the IMC layers in the order of increasing hardness and modulus are found to be Cu 6Sn 5, Cu 3Sn, (Cu x ,Ni 1− x ) 6Sn 5 and (Ni y ,Cu 1− y ) 3Sn 4.

143 鉛フリーはんだ/めっき銅薄膜金属間化合物の機械的特性(材料力学III)

143 鉛フリーはんだ/めっき銅薄膜金属間化合物の機械的特性(材料力学III)

203 鉛フリーはんだ/めっき銅薄膜金属間化合物の機械的特性(材料力学I,材料力学)

203 鉛フリーはんだ/めっき銅薄膜金属間化合物の機械的特性(材料力学I,材料力学)

Mechanical properties of intermetallic compounds on lead-free solder by moiré techniques

In this paper, methods for determining elastic moduli and coefficients of thermal expansion (CTE) of intermetallic compounds (IMC) formed at the interfaces between lead-free solder and metal substrates are presented. For the determination of elastic moduli, two kinds of lead-free solder—SnZn and Sn—were used; the metal substrates were copper and nickel. Nanoindentation techniques were adopted to determine the elastic moduli of Cu33.5Zn66.6, Cu3Sn, Cu6Sn5, and Ni3Sn4. Results for Cu33.5Zn66.6 are new to the literature, and others values are in good agreement with those presented in the literature. On the other hand, for CTE determination, two moire techniques, namely reflection moire and shadow moire, were developed to measure the deformation of IMC/metal composite structures subjected to thermal loading. Finite-element analyses using ANSYS were then performed as a convolutional process, and the genetic search algorithm was used to optimally obtain the CTE of IMC. The CTE of Cu33.5Zn66.6 was found to be approximate to that of copper, and the CTE of Cu3Sn was 10% larger. This method is also applicable to on-wafer films and IMC on micrometer order, such as the case of solder/IMC/under bump metallization.