Growth Of Intermetallic Compound Layer Research Articles

Investigation of microstructure, thermal properties, and mechanical performances of Ni-added Sn-5.0Sb-0.5Cu/Cu solder joints

Small amounts of Ni were added to Sn-5.0Sb-0.5Cu (SSC505) solder alloy. The added Ni slightly increased the melting temperature and slightly reduced the melting range of the alloy. The microstructure of the SSC505 solder included a β-Sn phase, and SbSn and Cu6Sn5 intermetallic compound (IMC) phases distributed in the solder matrix. The addition of Ni produced a new (Cu0.7,Ni0.3)6Sn5 IMC phase with a mixed morphology comprising hexagonal and flake-shaped phases. The addition of 0.1wt.%Ni increased the ultimate tensile strength (UTS) and hardness of the SSC505 solder to 43.31 MPa and 17.52 HV, respectively, but the addition of 0.2wt.%Ni increased the size and number of the IMC phases, which weakened both properties. The interfacial layers of SSC505/Cu solder joints were composed of Cu6Sn5 and Cu3Sn IMC layers. The addition of Ni inhibited the growth of the Cu3Sn IMC layers, but produced a new, thicker, dendritic IMC layer identified by energy dispersive X-ray spectroscopy (EDS) as (Cu0.96,Ni0.04)6Sn5. As a result, the shear strength of the SSC505-0.2Ni/Cu solder joint was low. This work showed that the microstructure and mechanical performances of both a SSC505 solder alloy and SSC505/Cu solder joint were improved by the addition of 0.1wt.%Ni.

Numerical analysis of the effect of heat loss by zinc evaporation on aluminum alloy to hot-dip galvanized steel joints by electrode negative polarity ratio varied AC pulse gas metal arc welding

In joining of aluminum alloy to hot-dip galvanized (GI) steel by arc welding-brazing process, evaporation of zinc (Zn) layer and formation of brittle Fe Al intermetallic compound (IMC) layer can affect the joint quality both thermally and metallurgically. At this point, the alternate current pulse gas metal arc welding (AC pulse GMAW) process is an excellent joining method because of its relatively low heat input to the base metal by controlling the electrode negative polarity (EN) ratio in its current waveform. In this study, a numerical analysis of joining 1.2 mm-thick GI steel to 1.2 mm-thick AA5052 aluminum alloy in the lap configuration using AC pulse GMAW was conducted to determine the effect of the EN ratio and Zn evaporation on joint quality. Based on the finite element method (FEM) 3D heat transfer model, the heat conduction analysis and the estimation of the IMC layer growth at the joint interface were carried out. The calculated results were validated with the corresponding experimental results and demonstrated a fair agreement. The results indicated that the temperature-dependent Zn mass evaporation and the increased EN ratio decrease the heat input to the joint interface. In particular, the heat loss caused by Zn evaporation with its latent heat restricts the growth of the brittle Fe Al IMC layer, which follows a function of temperature variation per unit length and time, by decreasing the heat from the arc to the joint interface. A 7.83 μm-thick IMC layer was obtained at a welding current of 55 A with an EN ratio of 20%, and a sound dissimilar material joint was achieved.

Formation and growth behavior of intermetallic compound phases in the interfacial reaction of solid Fe / liquid Zn at 450 °C

In the present study, the formation and growth behaviors of intermetallic compound (IMC) layers in the interfacial reaction of solid Fe and molten Zn during hot dipping at 450 °C were investigated. In the early stage of the interfacial reaction, Γ-Fe4Zn9, δ1k-FeZn7, and ζ-FeZn13 phases were formed, among which the growth of the ζ layer was dominant. Columns of the δ1p-Fe13Zn126 phase were formed on the δ1k/ζ interface at approximately 90 s, and the four IMC layers grew simultaneously until 600 s. Subsequently, a layer of the Γ1-Fe21.2Zn80.8 phase was formed along the Γ/δ1k interface and started growing, after which all the equilibrium IMC phases of Γ/Γ1/δ1k/δ1p/ζ grew competitively. The total thickness of the five IMC layers, dtotal, increased proportionally with the square root of the reaction time, t, i.e., dtotal = d0t0.5, which suggested that the growth of the entire IMC layers was controlled by the volume diffusion. However, the values of the time exponent, n, for the individual IMC layers differed depending on their microstructures and chemical concentrations, under equilibrium or nonequilibrium conditions. The formation of the multilayered columnar ζ phase can be attributed to the heterogeneous supersaturation of Fe in the liquid Zn near the columnar ζ / liquid Zn interface during the early stage of the interfacial reaction. The interdiffusion fluxes, J̃ϕ, of Fe and Zn in the ϕ phase (ϕ = Γ, δ1k, and ζ) were estimated from the measured concentration profiles of each phase. This suggested that J̃ϕ caused the growth of each phase as well as the supersaturation of Fe near the interfacial boundaries, thereby resulting in considerable deviations from the equilibrium concentrations. In the later stage of the interfacial reaction, the interfacial concentrations gradually approached the equilibrium concentrations with decreasing J̃ϕ.

Microstructural evolution of the Sn-51Bi-0.9Sb-1.0Ag/Cu soldering interface during isothermal aging

Development of lead-free solders with a melting point lower than that of the most widely used Sn-3.0Ag-0.5Cu (SAC305) is crucial for coping with the welding defects of ultra-thin microchips. The Sn-58Bi solder with a low melting point of 138 °C is a promising one. However, some severe issues of this solder, such as the brittle failure of soldering interface and the serious coarsening of the intermetallic compound (IMC) in the solder/Cu matrix interface, have hindered its applications in microelectronic assembly industries. In this work, the morphologies and layer thicknesses of interfacial intermetallic compounds between the Sn-51Bi-0.9Sb-1.0Ag solder and Cu substrate during the isothermal aging at 125 °C have been investigated. The results show that the scallop-like intermetallic compound layers of different curvature radii are formed at the solder joint interfaces. The main phase composition of the IMC layer is Cu6Sn5. After the isothermal aging treatment, the IMC layer gradually becomes a flat layer. The IMC thickness of the Sn-51Bi-0.9Sb-1.0Ag/Cu soldering interface at the stable state is thinner by 33% compared to that of the Sn-58Bi/Cu interface. By fitting the experimental data, the growth rate constant of the IMC layer in the Sn-51Bi-0.9Sb-1.0Ag/Cu solder joint is 2.060 × 10–18 m2·s−1, while it is 7.302 × 10–18 m2·s−1 in the Sn-58Bi/Cu solder joint. The present study indicates that the addition of Sb and Ag elements can substantially suppress the IMC layer growth.

Intermetallic Compound Layer Growth at the Interface between Sn-Ag and ENImAg Surface Finish

Intermetallic Compound Layer Growth at the Interface between Sn-Ag and ENImAg Surface Finish

Experimental and Theoretical Studies of Cu-Sn Intermetallic Phase Growth During High-Temperature Storage of Eutectic SnAg Interconnects

In this paper, the growth of intermetallic compound (IMC) layers is considered. After soldering, an IMC layer appears and establishes a mechanical contact between eutectic tin-silver solder bumps and Cu interconnects in microelectronic components. Intermetallics are relatively brittle in comparison with copper and tin. In addition, IMC formation is typically based on multi-component diffusion, which may include vacancy migration leading to Kirkendall voiding. Consequently, the rate of IMC growth has a strong implication on solder joint reliability. Experiments show that the intermetallic layers grow considerably when the structure is exposed to heat. Mechanical stresses may also affect intermetallic growth behavior. These stresses arise not only from external loadings but also from thermal mismatch of the materials constituting the joint, and from the mismatch produced by the change in shape and volume due to the chemical reactions of IMC formation. This explains why in this paper special attention is being paid to the influence of stresses on the kinetics of the IMC growth. We develop an approach that couples mechanics with the chemical reactions leading to the formation of IMC, based on the thermodynamically sound concept of the chemical affinity tensor, which was recently used in general statements and solutions of mechanochemistry problems. We start with a report of experimental findings regarding the IMC growth at the interface between copper pads and tin based solder alloys in different microchips during a high temperature storage test. Then we analyze the growth kinetics by means of a continuum model. By combining experiment, theory, and a comparison of experimental data and theoretical predictions we finally find the values of the diffusion coefficient and an estimate for the chemical reaction constant. A comparison with literature data is also performed.

Effect of crystal structure of nickel substrates on interfacial behaviors in Sn/Ni soldered joints

The effects of crystal structure of Nickel on the interfacial phase and growth mechanism were clarified in Sn/Ni soldered joints by using polycrystal nickel and single crystal nickel substrate. It was found that the intermetallic compounds (IMCs) phase, Ni3Sn4, was formed at the interface of Sn/polycrystal nickel joints; while, it changed into NiSn4 when using single crystal nickel substrate. At the following thermal aging process, Ni3Sn4 and NiSn4 exhibited different behaviors: Ni3Sn4 grew faster than NiSn4 showing a much thicker layer. Kinetics analysis indicated that different diffusion mechanisms governed the IMCs layer growth, namely Ni3Sn4 was controlled by diffusion of the reaction elements, whereas NiSn4 was controlled by reaction rate.

Shear strength and fracture surface analysis of lead-free solder joints with high fraction of IMCs

The effects of high fraction of intermetallic compounds (IMCs) on the shear strength and fracture mechanism of Cu/Sn3Ag0.5Cu/Cu solder joints were investigated. Reflowing at 250 °C up to 60 min, then isothermal aging was conducted at 150 °C with multiple aging time. The results showed that the thickness of Cu3Sn IMC gradually increased with the extending of reflowing time and aging time. In addition, the shear strength of solder joints decreased with increasing reflowing time and aging time, which was due to the excessive growth of the interfacial IMC layer. From the fractography, the brittle fracture mode was observed because of the Cu6Sn5 and Cu3Sn appeared on each fracture surface in all of shear samples. Furthermore, the area ratio of Cu3Sn on the fractured surfaces increased with the increment of reflowing time and aging time. In addition, the hardness and the Young's modulus of Cu3Sn decreased initially and then increased with increased reflowing time.

Morphological Effect on the Intermetallic Compound Layer Growth Kinetics of Metallurgical Joining

Evaluating the growth kinetics is one of the most important characteristic in assessing the quality and reliability of metallurgical joining, especially in electronics packaging such as soldering and wire bonding technology. The growth kinetics is normally assessed using Arrhenius equation that involves diffusion activities due to thermally activated process. The well-known factors of thermal and time together with generally accepted growth exponent have been widely used for this assessment. The intermetallic compound layer which is the by-product of metallurgical reaction during soldering process has been exposed to high temperature to accelerate its growth. The cross-section of the joining was observed using optical microscope to quantify the layer of intermetallic compound. Morphological effect and shape factor of the layer have been analysed in complement with the effect of temperature and time on the growth behaviour. Directional growth and irregularities shape of the intermetallic layer show some inconsistency on the selection of growth exponent. The effect of initial size of intermetallic layer must also be considered in this assessment. This study suggests that the morphological effect must be analysed prior to the selection the growth exponent in assessing growth behaviour and kinetics of intermetallic layer in metallurgical joining.

Influence of graphene content and nickel decoration on the microstructural and mechanical characteristics of the Cu/Sn–Ag–Cu/Cu soldered joint

In this research article, lead-free nanocomposite soldering is assessed by using the eutectic composition of Sn-3.5Ag-0.7Cu (SAC, wt%) solder alloy as the matrix and graphene nanoplatelets (GNPs) as the reinforcing agent. Powders of these materials are mixed in a mechanical milling system, then compacted, and sintered before application. The effects of GNPs content with different amounts of 0.05, 0.1, and 0.2wt% are examined to prepare nanocomposite solders as compared to the SAC solder alloy. Furthermore, to improve the metallurgical compatibility between the graphene and SAC solder matrix, the surface of GNPs was decorated by nickel particles using electroless plating techniques before incorporation. After that, the solderability of these prepared lead-free nanocomposite solders is investigated on the copper substrate. As the main result, the formation of the intermetallic compound (IMC) layers at the interface between the Cu-substrate and solder material was found very determinative to control the mechanical performance of soldered joints during lap-shear testing. The content of GNPs and Ni-coating modification strongly affected the morphology and growth of IMC layers at the interface. By increasing the amount of GNPs up to ∼0.2wt% and using Ni-coating, the growth of IMC layers was considerably suppressed, leading to a significant improvement of the joint strength up to ∼27%, despite a reduction of ∼50% of the ductility. Furthermore, isothermal aging at 150°C up to 100h resulted in a remarkable increase in the shear strength (∼45%) and elongation to failure (∼19.9%) through controlling the growth of the IMC layers at the interface.

Effect of (Ni, Au)3Sn4 growth on the thermal resistance of Au-20 wt% Sn solder/ENIG joint in flip-chip LED packages

In this study, the effect of growth of intermetallic compound (IMC) layer between Au-20 wt% Sn solder and electroless Ni/immersion Au (ENIG) on the thermal resistance of a flip-chip (FC) light emitting diode (LED) package was investigated. Two IMC layers were formed at the interface of FC LED package, including Au5Sn and (Ni, Au)3Sn4 that were identified using a transmission electron microscopy. A thermal aging test was carried out at 200 °C for 1000 h to observe IMCs growth. After 1000 h, the (Ni, Au)3Sn4 thickness increased to about 1.5 μm and the thermal resistance of the FC LED package increased by 3.5 times compared to the initial thermal resistance of 2 K W−1. As the (Ni, Au)3Sn4 grew, a calculation of thermal resistance also increased comparing to the initial aging test, thus, the growth of (Ni, Au)3Sn4 layer can be effective factor on the increase of thermal resistances of FC LED package.

Microstructure evolution and hardness of MWCNT-reinforced Sn-5Sb/Cu composite solder joints under different thermal aging conditions

In this work, multi-walled carbon nanotubes (MWCNTs) reinforced Sn-5Sb/Cu composite solder joints were synthesized and the effects of MWCNTs addition on the microstructure evolution and hardness of the Sn-5Sb solder alloy during various thermal aging conditions were investigated. After conducting a thorough microstructural analysis, the SbSn and Cu6Sn5 intermetallic compounds (IMCs) were observed in the β-Sn matrix of the composite solder joints subjected to reflow soldering while the latter was also present at the solder/Cu interface. However, after subjecting the composite solder joints to isothermal aging, the Cu3Sn IMC emerged between the Cu6Sn5 IMC at the solder/Cu interface and the Cu substrate. With the promising properties exhibited by MWCNTs as a reinforcement material, experimental results showed that MWCNTs refined the bulk solder microstructure and inhibited growth of the interfacial IMC layer in the Sn-5Sb-xCNT/Cu samples. In general, the composite sample reinforced with 0.05 wt% MWCNTs showed the least IMC layer thickness and diffusion coefficient in the ranges of 2.6–11.99 μm and 1.07 × 10−14-14.9 × 10−14 cm2/s respectively. Meanwhile, the strengthening mechanism triggered by MWCNTs addition was clearly evident in the MWCNT-reinforced Sn-5Sb/Cu as superior hardness values within a range of 20.6–15.3 HV were registered for the as-soldered and aged composite solder joints with 0.05 wt% MWCNTs reinforcement.

Effect of Ca element on oxygen content, wetting and spreading properties of Au–Ga filler metal

To meet the low oxygen content requirement on filler metals used in high reliable vacuum brazing of power device, Ca was doped into the Au–Ga filler metal, and the effects of Ca on the oxygen content, the wetting and spreading properties of the filler metal were investigated. The results reveal that Ca can effectively decrease the oxygen content in the Au-Ga-Ca filler metal, and the wettability and spreadability of the Au-Ga-Ca filler metal on the Cu substrate were significantly improved. With 0.004 wt % of Ca addition, the oxygen content in the filler metal decreased to 0.0032 wt % and the spreading area increased to a peak value of74.6 mm2. Proper amount of Ca addition can also effectively restrain the growth of intermetallic compounds (IMC) layer at the vacuum brazed filler metal/Cu interface and improve the shear strength of the joints. For the Cu/Au-Ga-0.004Ca/Cu joints vacuum brazed at 480 °C and a vacuum degree of 5 × 10−3 mbar, the IMC/filler metal interface is flat and the IMC layer is uniform in thickness, and shear strength of the joint was 48.3 MPa, 49.5% higher than the Cu/Au–Ga/Cu joint. It is demonstrated that the Au-Ga-0.004Ca filler metal has the best combination property, and high ratio of brazed area can be obtained with Au-Ga-0.004Ca filler metal at a proper vacuum degree in brazing of real components.

Evolution of interface and tensile properties in 5052 aluminum alloy/304 stainless steel rotary friction welded joint after post-weld heat treatment

The inhomogeneous properties of 5052 aluminum alloy/304 stainless steel rotary friction welded joint and the growth behavior of intermetallic compound (IMC) layer were investigated. The ultimate tensile strength (UTS) of as-welded joint in 0R location with discontinuous IMC layer reached the maximum value of 203 MPa, and that in R/2 and 3R/4 locations decreased with the increase of IMC layer thickness, but that in R/4 location was the lowest due to the initiation of crack. After post-weld heat treatment at 250 °C/20 min, the thickness of IMC layer remained invariant, but the UTS of entire joint increased from 153 MPa to 161.4 MPa. In addition, the difference of UTS along the radius direction decreased, which benefited the engineering application. During post-weld heat treatment at 450 °C, the growth of IMC layer in R/4, R/2 and 3R/4 location were faster than that in 0R location. However, the growth of IMC layer deviated from parabolic law, which was attributed to (i) a large number of dislocations, grain boundaries and storage energy in the interface, (ii) the linear growth of Fe4Al13 phase, and (iii) the effect of Cr element.

Microstructural analysis of Sn-3.0Ag-0.5Cu-TiO2 composite solder alloy after selective electrochemical etching

This work aims to provide deep morphological observation on the incorporated TiO2 nanoparticles within the SAC305 by selective electrochemical etching. Cyclic voltammetry and chronoamperometry were used to investigate the selective etching performances. The removal of β-Sn matrix was conducted at a fixed potential of −350 mV. Average performances of 2.19 and 2.30 mA were attained from the chronoamperometry. The efficiency of β-Sn removal was approved according to the reduction of the intensities on the phase analysis. Successful observation of the TiO2 near the Cu6Sn5 layer was attained for an optimum duration of 120 s. Clusters of TiO2 nanoparticles were entrapped by Cu6Sn5 and Ag3Sn intermetallic compound (IMC) layer network and at the solder/substrate interface. The presence of TiO2 nanoparticles at the solder interface suppresses the growth of the Cu6Sn5 IMC layer. The absence of a β-Sn matrix also allowed in-depth morphological observations to be made of the shape and size of the Cu6Sn5 and Ag3Sn. It was found that TiO2 content facilitates the β-Sn removal, which allows better observation of the IMC phases as well as the TiO2 reinforcement particles.

Effect of Aging Temperature on the Microstructure and Shear Strength of SAC0307-0.1Ni Lead-Free Solders in Copper Joints

This paper presents an investigation of the effects of aging temperature on the microstructure and shear strength of SAC0307-0.1Ni/Cu solder joints. Single-overlap shear solder joints were aged for 1 h at 80, 130, and 180°C. The microstructure of the interface between the solder and the Cu substrate contained phase of the intermetallic compounds (IMCs) (Cu,Ni)6Sn5 formed along the interface. The shape of scallop-like (Cu,Ni)6Sn5 IMCs changed to the long dendrite and grew larger at the interface of solder joints after increased aging temperature. In addition, a phase of particle-like Ag3Sn IMCs was formed in the solder matrix. The growth of the interfacial IMC layer in the solder joints increased with increasing the aging temperature. The thickness of this layer was controlled by diffusion mechanism. The shear strength of the as-reflowed solder joints was greater than that of the aged solder joints, and the shear strength of all the aged solder joints decreased with increasing the aging temperatures. Therefore, the aging temperature mainly affected the thickness of the interfacial layer of IMCs and the shear strength of the solder joints.

Effect of Zn Addition on Interfacial Reactions and Mechanical Properties Between Eutectic Sn58Bi Solder and ENIG Substrate.

A comprehensive study of the interfacial reactions between Zn-added Sn58Bi solder alloys and electroless Ni/immersion Au (ENIG) substrates during reflow and solid-state thermal aging was conducted. The shear strengths of these samples were tested before and after aging. Zn first reacted with Au forming AuZn₃ intermetallic compounds (IMCs) that detached in small pieces from the substrate and immediately moved into the solder bulk. A very thin Au-Zn-Ni-Sn IMC layer was observed attached to the substrate. This layer, with a thickness of 0.25 μm, significantly suppressed IMC layer growth during thermal aging, resulting in a thermally stabled joint. By contrast, the thickness of the (Au, Ni)(Sn, Bi)₄ IMC layer on the eutectic Sn58Bi/ENIG interface doubled during aging and, therefore, its shear strength decreased.

Joining mechanism and mechanical properties of metallic bump assisted weld-bonded (MBaWB) joints of AA6061-T6 and bare DP590

A novel metallic bump assisted weld bonding (MBaWB) process was proposed to join Al and steel sheets, aiming to systematically resolve the over-thick intermetallic compound (IMC) layer, corrosion and deformation issues of Al-steel resistance spot-welded joints. The nugget morphology, microstructure and mechanical properties of the MBaWB welds were investigated in this paper. Compared with the traditional resistance spot weld bonding (RSWB) process, the MBaWB welds achieved larger Al nugget, fewer defects, and thinner IMC layer, benefited from the introduction of a Si-riched metallic bump to expel the residual adhesive, to change the heat distribution, and to inhibit the growth of IMC layer. As a result, the MBaWB process achieved approximately 47.0 % improvement in lap-shear strength of uncured joints. For cured joints, the coach-peel strength and energy absorption of MBaWB joints reached 51.2 % improvement and about 6.3 times higher than that of the RSWB joints, respectively.

Shear strength, fracture mechanism and plastic performance of Cu/Sn5Sb–xCuNiAg/Cu solder joints during thermal aging

The shear strength, fracture mode, fracture position and the plastic behavior of the Cu/Sn5Sb–xCuNiAg/Cu were investigated. Experimental results demonstrated that the Cu/Sn5Sb–0.5Cu–0.1Ni–0.5Ag/Cu joints has higher shear strength during the aging time compared with the Cu/Sn5Sb/Cu joints and Cu/Sn–3.0Ag–0.5Cu(SAC305)/Cu joints. The shear strength decreased from 93.1 to 78.8 MPa as the aging time increased from 0 to 192 h. When the aging time increased from 192 to 336 h, the shear strength presented a slightly decrease from 78.8 to 76.8 MPa. The addition of trace elements Cu, Ni and Ag increases the shear strength of the Sn5Sb due to the solid solution strengthening, precipitation strengthening, and fine grain strengthening. The fracture mode of Cu/Sn5Sb–0.5Cu–0.1Ni–0.5Ag/Cu joint changed from ductile fracture to ductile–brittle hybrid fracture during the HTS aging. At the same time, the fracture position is always at the matrix solder at different aging time. In contrast, the fracture modes of Cu/Sn5Sb/Cu and Cu/SAC305/Cu solder joints changed from ductile fracture to brittle fracture and the fracture position changed from matrix solder to a mixed position near the interfacial IMC. Compared with Cu/Sn5Sb/Cu and Cu/SAC305/Cu, Cu/Sn5Sb–0.5Cu–0.1Ni–0.5Ag/Cu joint has the best plastic deformation ability, and its plastic deformation ability changes slightly with the extension of aging time. The addition of Cu, Ni and Ag elements increases the fine uniform intermetallic compounds (IMCs) in the matrix solder and suppresses the growth of the interfacial IMC layer. This increases the solder joint toughness and reduces the brittleness, which leads to the changes of the fracture mode and fracture position.

Effect of nano-ZnO particles on wettability, interfacial morphology and growth kinetics of Sn–3.0Ag–0.5Cu–xZnO composite solder

The influence of nano-ZnO particles addition on wettability, thermal behavior and interface morphology of Sn–3.0Ag–0.5Cu (SAC305) lead-free solder were investigated in present study. SAC305-xZnO composite solder with five different mass fractions of nano-ZnO particles ranging from 0 to 2.0 wt% were synthesized with SAC305 powder, nano-ZnO particles and flux. Solder joints were soldered in a reflow furnace with the maximum temperature of 255 °C for 7 min and followed by isothermal aging at 170 °C up to 240 h. The results reveal that the wettability improves first and then reduces whereas the thickness of intermetallic compounds (IMCs) layer declines first and then increases with the amount of nano-ZnO particles increasing where the threshold occurs at 0.5 wt% nano-ZnO particles, meaning slight addition of nano-ZnO particles can effectively improve wettability as well as restrain IMCs layer growth. The thermal behaviors of SAC305-xZnO composite solder increases slightly as nano-ZnO particles adds from 0 to 2.0 wt%. Moreover, the diffusion coefficient of solder is 0.92 μm2/h, 0.21 μm2/h, 0.22 μm2/h, 0.37 μm2/h and 0.48 μm2/h in sequence with nano-ZnO particles increased from 0 to 2.0 wt%, revealing nano-ZnO particles can inhibit atoms diffusion so as to suppress IMCs layer. Furthermore, the grain size of Cu6Sn5 is observed that it increases with power function of aging time describing as \(d = 1.70t^{0.38}\). In the end, it reveals that Cu6Sn5 grows both longitudinally controlled by volume diffusion as well as transversely in the form of boundary diffusion.