Sn Interlayer Research Articles

A Study on the Effects Bonding Temperature and Holding Time on Mechanical and Metallurgical Properties of Al–Cu Dissimilar Joining by DFW

The aim of this study was to evaluate the influence of bonding temperature and holding time on the metallurgical and mechanical properties for weld joints of 5 mm aluminum to copper using Sn interlayer. The bonding temperature varied from 500 to 600 °C whilst the holding time varied from 30 to 120 min under 8 MPa uniaxial load in 1 × 10−4 torr vacuum. The microstructure analysis, phase analysis and distribution of elements in the interface were performed by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and element map analysis. It was found that diffusion welding parameters had a significant effect on shear strength. The attained data of tensile strength tests showed that the shear strength increased with increasing bonding temperature and holding time, although in 120 min, the holding time had a bilateral effect on the shear strength and shear strength dropped marginally as holding time increased. The highest shear strength value was 110 MPa which was obtained for the samples joined for 60 min holding time and 600 °C bonding temperature. Further, the results showed that parameters had significant effect on the thickness of reaction layers.

Intermetallic Reactions during the Solid-Liquid Interdiffusion Bonding of Bi2Te2.55Se0.45 Thermoelectric Material with Cu Electrodes Using a Sn Interlayer

The intermetallic compounds formed during the diffusion soldering of a Bi2Te2.55Se0.45 thermoelectric material with a Cu electrode are investigated. For this bonding process, Bi2Te2.55Se0.45 was pre-coated with a 1 μm Sn thin film on the thermoelectric element and pre-heated at 250 °C for 3 min before being electroplated with a Ni barrier layer and a Ag reaction layer. The pre-treated thermoelectric element was bonded with a Ag-coated Cu electrode using a 4 μm Sn interlayer at temperatures between 250 and 325 °C. The results indicated that a multi-layer of Bi–Te–Se/Sn–Te–Se–Bi/Ni3Sn4 phases formed at the Bi2Te2.55Se0.45/Ni interface, ensuring sound cohesion between the Bi2Te2.55Se0.45 thermoelectric material and Ni barrier. The molten Sn interlayer reacted rapidly with both Ag reaction layers to form an Ag3Sn intermetallic layer until it was completely exhausted and the Ag/Sn/Ag sandwich transformed into a Ag/Ag3Sn/Ag joint. Satisfactory shear strengths ranging from 19.3 and 21.8 MPa were achieved in Bi2Te2.55Se0.45/Cu joints bonded at 250 to 300 °C for 5 to 30 min, dropping to values of about 11 MPa for 60 min, bonding at 275 and 300 °C. In addition, poor strengths of about 7 MPa resulted from bonding at a higher temperature of 325 °C for 5 to 60 min.

Improving weld strength of arc-assisted ultrasonic seam welded Mg/Al joint with Sn interlayer

Welding of Mg and Al alloys is hugely challenging due to the formation of hard and brittle MgAl intermetallic compounds (IMCs). In this research, gas tungsten arc welding (GTAW) assisted hybrid ultrasonic seam welding with Sn interlayer was designed to join Mg to Al alloys. Effects of Sn interlayer and GTAW current on the microstructure and mechanical properties of the joints were investigated in detail. The results indicated that Sn interlayer could restrain the formation of MgAl IMCs, which were replaced by Mg2Sn and Sn-based solid solution. The peak load of the joints increased with the GTAW current increasing and then decreased dramatically at higher GTAW current. The maximum peak load of the joints with Sn interlayer was approximately 1.3kN, which about 30% increase over the joints without Sn interlayer. All the joint failures occurred by the interface mode at the Al/Sn interface and the fracture patterns exhibited entirely brittle fracture mode with cleavage facet feature surface.

Effect of Process and Service Conditions on TLP-Bonded Components with (Ag,Ni–)Sn Interlayer Combinations

Transient liquid phase (TLP) bonding of Cu substrates was conducted with interlayer systems with the stacking sequences Ag–Sn–Ag (samples A), Ni–Sn–Ni (samples B), and combined Ag–Sn–Ni (samples C). Because of the low mismatch of the coefficients of thermal expansion, characteristics of the TLP process and mechanical and thermal behavior of TLP-bonded samples could be investigated without interference from thermally induced residual stresses. An ideal process temperature of 300°C, at which the number of pores was lowest, was identified for all three layer systems. It was verified experimentally that formation of pores resulted from volume contraction during isothermal solidification of liquid Sn into intermetallic compounds (IMC). Temperature and interlayer-dependent growth characteristics of IMC accounted for the increasing size and number of defects with increasing process temperature and for different defect positions. The shear strength was measured to be 60.4 MPa, 27.4 MPa, and 40.7 MPa for samples A, B, and C, respectively, and ductile fracture features were observed for Ag3Sn IMC compared with the purely brittle behavior of Ni3Sn4 IMC. Excellent thermal stability for all three layer systems was confirmed during long-term annealing at 200°C for up to 1200 h, whereas at 300°C the microstructure was driven toward Ag–Sn solid solution, accompanied by Cu diffusion from the substrate along grain boundaries and Cu3Sn IMC formation (A), and toward Ni-rich IMC phases (B). Combined IMC interlayers (C) tended to be transformed into Ni-based IMC when held at 300°C; intermixing into (Ni,Cu)3Sn was accompanied by pore formation.

The application of equal channel angular pressing to join dissimilar metals, aluminium alloy and steel, using an Ag–Cu–Sn interlayer

Abstract Joining cylindrical and bar-shaped components manufactured from dissimilar materials is frequently required in various industrial applications. The current study focuses on developing equal channel angular pressing (ECAP) as a severe plastic deformation process for solid state joining of tubular aluminium alloy 6061 components and SAE 1018 steel rods. The influence of using a 0.1 mm thick 60Ag–30Cu–10Sn interlayer in addition to annealing at 220, 320, 420 and 520 °C for 60 min is investigated as well. Finite element analysis (FEA) is performed in order to evaluate the deformation behaviour of the workpieces during the ECAP joining process. XRD and EDX analyses as well as nanoindentation and shear tests are carried out to evaluate the joints' characteristics. The FEA outcomes show remarkable accumulation of equivalent plastic strain with relatively low strain inhomogeneity. Moreover, the experimental results indicate that with increasing annealing temperature, joint strength exhibits improvement as well. It is also revealed that the application of an interlayer at any specific annealing temperature leads to achieving higher shear strength values. According to the results, shear strength of up to 32 MPa is feasible by having an interlayer and with subsequent annealing at 520 °C.

Influence of hydrogen surface passivation on Sn segregation, aggregation, and distribution in GeSn/Ge(001) materials

Plane-wave density functional theory is used to investigate the impact of hydrogen passivation of the p(2×2) reconstructed Ge1−xSnx surface on Sn segregation, aggregation, and distribution. On a clean surface, Sn preferentially segregates to the surface layer, with surface coverages of 25%, 50%, and 100% for total Sn concentrations of 2.5%, 5.0%, and 10.0%, respectively. In contrast, a hydrogen passivated surface increases interlayer migration of Sn to subsurface layers, in particular, to the third layer from the surface, and results in surface coverages of 0%, 0%, and 50% corresponding to Sn concentrations of 2.5%, 5.0%, and 10.0%, respectively. Hydrogen transfer from a Ge-capped surface to the one enriched with increasing Sn surface coverage is also an unfavorable process. The presence of hydrogen therefore reduces the surface energy by passivating the reactive dangling bonds and enhancing Sn interlayer migration to the subsurface layers. For both clean and hydrogenated surfaces, aggregation of Sn at the surface layer is also not favored. We explain these results by considering bond enthalpies and the enthalpies of hydrogenation for various surface reactions. Our results thus point to reduced Sn segregation to the surface in a Ge1−xSnx epitaxial thin film if CVD growth, using hydride precursors in the hydrogen limited growth regime, is used. This would lead to a more abrupt interface and is consistent with recent experimental observation. Hydrogenation is therefore a promising method for controlling and manipulating elemental population of Sn in a Ge1−xSnx epitaxial thin film.

Early stage growth characteristics of Ag3Sn intermetallic compounds during solid–solid and solid–liquid reactions in the Ag–Sn interlayer system: Experiments and simulations

Transient Liquid Phase Bonding (TLPB) makes use of the isothermal solidification of a liquid interlayer through the formation of intermetallic compounds (IMC). This work investigates the Ag3Sn IMC formation in a thin, electroplated Ag–Sn interlayer system appropriate for TLPB – while covering as-coated conditions, growth initiation up to a few minutes of holding time – with experimental and numerical methods. Both solid-state and solid–liquid reactions at 200, 250 and 300°C, respectively, were covered under identical and near-isothermal conditions with a novel experimental setup. Morphological aspects like the lateral IMC grain size or the scallop roughness were proven to strongly depend on temperature. Growth kinetics were captured by power laws, growth exponents n were determined as 0.24, 0.36 and 0.29, parabolic growth constants k as 1.32⋅10−11, 4.04⋅10−10 and 7.24⋅10−10cm2/s at 200, 250 and 300°C, respectively, and the activation energy Q as 30.6kJ/mol. Predominant diffusion mechanisms, i.e. volume or GB diffusion, as well as coarsening effects were identified as temperature and time dependent at early stages. A mathematical model was developed based on the Arrhenius relationship including a growth correction function zIMC,corr to calculate and predict IMC growth as a function of temperature and time. The study was completed by multiphase-field simulations which targeted to mimic kinetic and morphological features of Ag3Sn IMC under various conditions. Good agreement between experiments and simulations was found for a limited set of parameters which allowed drawing conclusions about the dominant transport mechanisms for the reacting elements.

The low-temperature form of calcium gold stannide, CaAuSn

The EuAuGe-type CaAuSn phase has been synthesized and single-crystal X-ray diffraction analysis reveals that it has an orthorhombic symmetry (space group Imm2), with a = 4.5261 (7) Å, b = 7.1356 (11) Å and c = 7.8147 (11) Å. The structure features puckered layers that are connected by homoatomic Au-Au and Sn-Sn interlayer bonds. This structure is one of the two parent structures of its high-temperature polymorph (ca 873 K), which is an intergrowth structure of the EuAuGe- and SrMgSi-type structures in a 2:3 ratio.

Suitable Thicknesses of Base Metal and Interlayer, and Evolution of Phases for Ag/Sn/Ag Transient liquid-phase Joints Used for Power Die Attachment

Real Si insulated gate bipolar transistors with conventional Ni/Ag metallization and dummy Si chips with thickened Ni/Ag metallization have both been bonded, at 250°C for 0 min, 40 min, and 640 min, to Ag foil electroplated with 2.7 µm and 6.8 µm thick Sn as an interlayer. On the basis of characterization of the microstructure of the resulting joints, suitable thicknesses are suggested for the Ag base metal and the Sn interlayer for Ag/Sn/Ag transient liquid-phase (TLP) joints used for power die attachment. The diffusivities of Ag and Sn in the ξAg phase were also obtained. In combination with the kinetic constants of Ag3Sn growth and diffusivities of Ag and Sn in Ag reported in the literature, the diffusivities of Ag and Sn in the ξAg phase were also used to simulate and predict diffusion-controlled growth and evolution of the phases in Ag/Sn/Ag TLP joints during extended bonding and in service.

Dissimilar ultrasonic spot welding of Mg-Al and Mg-high strength low alloy steel

Sound dissimilar lap joints were achieved via ultrasonic spot welding (USW), which is a solid-state joining technique. The addition of Sn interlayer during USW effectively blocked the formation of brittle al12Mg17 intermetallic compound in the Mg-Al dissimilar joints without interlayer, and led to the presence of a distinctive composite-like Sn and Mg2Sn eutectic structure in both Mg-Al and Mg-high strength low alloy (HSLA) steel joints. The lap shear strength of both types of dissimilar joints with a Sn interlayer was significantly higher than that of the corresponding dissimilar joints without interlayer. Failure during the tensile lap shear tests occurred mainly in the mode of cohesive failure in the Mg-Al dissimilar joints and in the mode of partial cohesive failure and partial nugget pull-out in the Mg-HSLA steel dissimilar joints.

Characterization of ultrasonic spot welded joints of Mg-to-galvanized and ungalvanized steel with a tin interlayer

Ultrasonic spot welded (USWed) Mg-to-bare steel, Mg-to-galvanized steel and Mg-to-bare steel with Sn interlayer (placed in-between Mg and bare steel) were studied. Weak joining occurred in the USWed Mg-to-bare steel, since Mg and Fe do not react with each other. The intermetallic compounds (IMCs) of Mg7Zn3 and Mg2Zn11, which led to the failure of the joint, were largely present in the USWed Mg-to-galvanized steel joint. The introduction of a Sn interlayer in the USWed Mg-to-bare steel actively worked as an intermediate medium to join Mg to Fe, and led to the presence of a distinctive composite-like Sn and Mg2Sn eutectic structure. The lap shear strength of Mg-to-bare steel with Sn interlayer joint was significantly higher than that of the Mg-to-bare steel and Mg-to-galvanized steel joints. Failure during the tensile lap shear tests occurred mainly in the partial nugget pull-out mode in the dissimilar joints of Mg-to-bare steel with Sn interlayer. All the joints of Mg-to-galvanized steel failed from the interface (cohesive failure). The addition of Sn interlayer resulted in energy saving since the welding energy required to achieve the maximum strength decreased from 1750 to 1500J in the Mg-to-steel joints.

Rapid formation of Cu/Cu3Sn/Cu joints using ultrasonic bonding process at ambient temperature

Wafer bonding using Sn interlayer and silicon bond components with Ti/Ni/Cu metallization was achieved by ultrasonic bonding at ambient temperature for 4 s under 0.6 MPa. High-melting-point joint which fully consisted of Cu3Sn intermetallic compounds was formed with a high shear strength of 65.8 MPa and a low electrical resistivity of 67.3 μΩ · cm. Experimental results showed that ultrasonic vibration induced steep temperature rise at rubbing interface, melting solid solder, and sequent ultrasonic effects at the liquid Sn/solid Cu interface dominated the mechanism and kinetics of rapid formation of Cu3Sn joint.

Interfacial reaction in Cu/Sn/Cu system during the transient liquid phase soldering process

A thin interlayer of pure Sn foil has been sandwiched between two pieces of Cu foil base metal and reflowed at 260, 300 and 340 °C, under 2%H 2/98%N 2 forming gas, for 5 – 480 min. We report here: (i) the interfacial microstructures to show Cu 6Sn 5 scallops and Cu 3Sn columnar crystals; (ii) the pronounced difference in the thicknesses of the Cu 6Sn 5 and Cu 3Sn layers formed at the two original boundary planes in the Cu/Sn/Cu samples; (iii) the diffusion-kinetic constants for the Cu 6Sn 5 and Cu 3Sn growth derived from the Cu/Sn/Cu samples for a range of Sn interlayer thicknesses; and (iv) a type of grain boundary/molten channel-controlled growth of Cu 6Sn 5 with a time dependence similar to that for the volume diffusion-controlled growth. These results provide new insight into the mechanism and kinetics of the interfacial reaction between liquid Sn and solid Cu, and other similar metallic liquid/solid systems.

Tin-induced enhancement of photoluminescence and crystal growth in Si-rich silica films

The effect of local Sn-doping on the photoluminescence (PL) properties of the Si-rich silica (SRSO) thin film was investigated. In order to dope Sn into the SRSO film, we introduced a Sn interlayer in the film. After annealing at temperatures higher than 1000 °C, the PL intensity of the Sn-doped samples was about 2 times higher than that of the undoped ones, while Sn-doped and undoped samples annealed at lower temperatures had almost the same PL intensities. The microstructure and mechanism of the PL improvement of this SiO x /Sn/SiO x system were analyzed by Raman scattering spectroscopy, Auger electron spectroscopy, and X-ray diffraction.

Structure, 119Sn solid state NMR and Mössbauer spectroscopy of RECuSn ( [formula omitted

X-ray pure samples of the stannides RECuSn ( RE = Sc , Y , La , Lu ) were prepared by arc-melting of the elements and subsequent annealing. The four stannides were investigated by X-ray powder and single crystal diffraction: ZrBeSi type, P 6 3 / m m c , a = 458.3 ( 2 ) , c = 817.3 ( 3 ) pm , w R 2 = 0.0746 , 148 F 2 values, 8 variable parameters for LaCuSn, NdPtSb type, space group P 6 3 m c , a = 451.3 ( 1 ) , c = 727.4 ( 2 ) pm , w R 2 = 0.0462 , 134 F 2 values, 10 variable parameters for YCuSn, a = 446.4 ( 2 ) , c = 709.0 ( 2 ) pm , w R 2 = 0.0214 , BASF = 0.47 ( 2 ) , 240 F 2 values, 12 variable parameters for LuCuSn and LiGaGe type, space group P 6 3 m c , a = 438.8 ( 1 ) , c = 683.0 ( 2 ) pm , w R 2 = 0.0328 , 220 F 2 values, 11 variable parameters for ScCuSn. The structures of the four stannides consist of layers of ordered [Cu 3Sn 3] hexagons. While the layers are planar in LaCuSn, a puckering effect is observed in YCuSn and LuCuSn. In ScCuSn with the smallest rare earth metal the puckering is that pronounced that a tetrahedral network occurs. The intralayer Cu Sn distances are similar in the four compounds (262–268 pm), but the Cu Sn interlayer distances decrease from 409 pm (LaCuSn) via 303 pm (YCuSn) and 289 pm (LuCuSn) to 276 pm (ScCuSn). Thus, as a function of the size of the rare earth metal, one observes a continuous transition from a two- to a three-dimensional [CuSn] network. The noncubic local symmetry at the tin site is reflected by a small nuclear electric quadrupolar splitting in the 119Sn Mössbauer spectra and a moderate chemical shift anisotropy in 119Sn solid state NMR. An inspection of all the 119Sn chemical shift anisotropies measured for RETSn compounds ( T = Cu , Ag , Au ) reveals an excellent correlation with the magnitude of the electric field gradient present at the tin site as calculated from crystal structural data by the WIEN2k program.

Experimental studies of solid state surface wetting of tin (Sn) on aluminium (Al)

Under ultra high vacuum (UHV) conditions tin (Sn) forms a monoatomic wetting layer on aluminium (Al) surfaces if Sn-islands formed by a preceding deposition process are present. Previous experimental observations and Kinetic Monte Carlo (KMC) simulations suggest that wetting layer formation is governed by thermally activated surface diffusion and adsorption processes. This paper presents a systematic study of the wetting of the inner and outer interfaces of Al by Sn in sandwich systems consisting of a 400 nm Al-base layer, a 10 nm Sn interlayer and a 400 nm thick Al capping layer. The morphology and chemical composition of the sandwich systems is investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The wetting process is studied by scanning auger electron spectroscopy (AES) under UHV conditions. Depositing the Al-capping layer at different deposition rates allows for the assessment of the influence of the grain boundary density on the velocity of Sn-transport through the Al-capping layer. Studying the permeation speed of Sn through the capping layer at different temperatures shows that Sn penetrates the capping layer much more rapidly at elevated temperatures thus corroborating the involvement of thermally activated mechanisms in the transport process. # 2005 Elsevier B.V. All rights reserved.

Lamellar growth in sputter-deposited aluminum–tin–aluminum sandwich layers

In recent experiments, the formation of lamellar features within an Al film was observed when deposited on a thin Sn layer. The present study investigates the influence of the deposition rate of the Al film on the lamella thickness to gain insight into the mechanism of lamella formation.Al–Sn–Al sandwich layers were prepared in HV by magnetron sputtering at 180 °C substrate temperature on natively oxidized Si wafers. Al and Sn were sequentially sputtered from a 100-mm diameter DC magnetron target. The samples consisted of an Al base layer (400 nm), a Sn interlayer (10 nm) and an Al capping layer (400 nm). The base layer and the Sn interlayer were deposited at a rate of 0.4 and 0.1 nm s−1, respectively. The deposition rate for the capping layer was varied between 0.1 and 0.8 nm s−1.Cross-sectional transmission electron microscopy (X-TEM) shows that, with increasing deposition rate of the capping layer, the lamella thickness slightly decreases. This is in contradiction to a previously formulated hypothesis of lamella growth which predicted an increase of lamella thickness with increasing deposition rate. On the other hand, contact mode atomic force microscopy (AFM) as well as X-TEM show a significant decrease of the Al grain size in the polycrystalline capping layer with increasing deposition rate. If the resulting higher grain boundary density is taken into account, the experimentally observed lamella thicknesses can reasonably be described by a model combining the diffusion of Sn along the Al grain boundaries and the oxidation of Sn on the growth surface.

Solid state diffusion of Sn in polycyrstalline Al films

The formation of a wetting layer of Sn and the Stranski–Krastanov growth of Sn on a polycrystalline Al film surface has been proved recently. In the present experiments the influence of Sn on the structure evolution of Al films has been analyzed in detail. The films were prepared in HV by magnetron sputtering at 180 °C substrate temperature on Si wafers covered by the native oxide. Al and Sn were sequentially sputtered from a 100-mm diameter DC magnetron target. The samples consisted of an Al-base layer (400 nm), a Sn interlayer (10 nm) and an Al-capping layer (400 nm) and were investigated by analytical and high resolution X-TEM, AFM and scanning AES. If the Sn-interlayer is oxidized, no effect on the growth of the Al-capping layer is observable. If, on the other hand, the Sn-interlayer is prevented from oxidation grain growth is promoted in the Al-capping layer as confirmed by X-TEM and AFM. The capping layer contains intragranular line-like features roughly parallel to the substrate plane. Microanalysis shows the presence of Sn in the capping layer and indicates that Sn is associated with these linear features. The promotion of grain growth in the capping layer can be attributed to the permanent transport of Sn to the growth front via grain boundaries which was confirmed by dynamic scanning AES-measurements. The linear intragranular feature formation is explained by the oxidation of Sn on the free surface due to the residual oxygen present in the background gas.

Structure and Properties of YbZnSn, YbAgSn, and Yb2Pt2Pb

YbZnSn, YbAgSn, and Yb2Pt2Pb were synthesized by reacting the elements in sealed tantalum tubes in a high-frequency furnace. The structures of YbAgSn and Yb2Pt2Pb were refined from single crystal X-ray data: YbAgPb type, P6m2, a=479.2(2) pm, c=1087.3(3) pm, wR2=0.050, BASF=0.34(8), 509 F2 values, 18 variables for YbAgSn and Er2Au2Sn type, a=776.0(1) pm, c=701.8(2) pm, wR2=0.072, 426 F2 values, 18 variables for Yb2Pt2Pb. The lattice constants of YbZnSn are confirmed: NdPtSb type, P63mc, a=464.7(1) pm, c=747.7(2) pm. The stannides YbZnSn and YbAgSn crystallize with superstructures of the AlB2 type. The zinc (silver) and tin atoms form ordered Zn3Sn3 and Ag3Sn3 hexagons, respectively. The stacking sequences for the differently oriented hexagons are AB, AB for YbZnSn and ABC, ABC for YbAgSn. While exclusively Zn–Sn intralayer interactions were observed in YbZnSn, intralayer Ag–Sn and significant Sn–Sn interlayer interactions at 318 pm occur in YbAgSn. The [ZnSn] and [AgSn] polyanions in YbZnSn and YbAgSn, respectively, have a pronounced two-dimensional character. This picture of chemical bonding in YbAgSn is confirmed by TB–LMTO–ASA band structure calculations. The partial densities-of-states and the valence charge densities are discussed. The magnetic (no long-range ordering, Yb2+) and the resistivity measurements (metallic behavior) are in excellent agreement with the electronic structure calculations. Yb2Pt2Pb crystallizes with the Er2Au2Sn structure, a ternary derivative of the Zr3Al2 type. This structure is composed of distorted AlB2 and CsCl related slabs of compositions YbPt2 and YbPb. Yb2Pt2Pb shows paramagnetic behavior (4.3±0.4 μB/Yb) indicating trivalent ytterbium. Magnetic susceptibility measurements on YbZnSn and YbAgSn show Pauli paramagnetism with room temperature susceptibilities of 2.5(1)×10−9 and 4.6(1)×10−9 m3/mol. Electrical resistivity measurements indicate metallic conductivity with specific resistivities of 440±40 μΩcm (YbZnSn) and 490±40 μΩcm (YbAgSn) at 300 K. 119Sn Mössbauer spectra of YbZnSn show a single signal at room temperature with an isomer shift of δ=1.85(1) mm/s. YbAgSn shows two superimposed signals at 78 K: a singlet at δ=1.94(1) mm/s and a second signal at δ=1.99(1) mm/s subjected to quadrupole splitting of ΔEQ=1.35(1) mm/s, in agreement with the two crystallographically different tin sites.

A general criterion for high-cycle multiaxial fatigue failure: McDiarmid, D.L. Fatigue Fract. Eng. Mater. Struct. 1991 14, (4), 429–453

Transient Liquid Phase Bonding (TLPB) makes use of the isothermal solidification of a liquid interlayer through the formation of intermetallic compounds (IMC). This work investigates the Ag3Sn IMC formation in a thin, electroplated Ag–Sn interlayer system appropriate for TLPB – while covering as-coated conditions, growth initiation up to a few minutes of holding time – with experimental and numerical methods. Both solid-state and solid–liquid reactions at 200, 250 and 300 °C, respectively, were covered under identical and near-isothermal conditions with a novel experimental setup. Morphological aspects like the lateral IMC grain size or the scallop roughness were proven to strongly depend on temperature. Growth kinetics were captured by power laws, growth exponents n were determined as 0.24, 0.36 and 0.29, parabolic growth constants k as 1.32 ⋅ 10−11, 4.04 ⋅ 10−10 and 7.24 ⋅ 10−10 cm2/s at 200, 250 and 300 °C, respectively, and the activation energy Q as 30.6 kJ/mol. Predominant diffusion mechanisms, i.e. volume or GB diffusion, as well as coarsening effects were identified as temperature and time dependent at early stages. A mathematical model was developed based on the Arrhenius relationship including a growth correction function zIMC,corr to calculate and predict IMC growth as a function of temperature and time. The study was completed by multiphase-field simulations which targeted to mimic kinetic and morphological features of Ag3Sn IMC under various conditions. Good agreement between experiments and simulations was found for a limited set of parameters which allowed drawing conclusions about the dominant transport mechanisms for the reacting elements.