Transient Liquid Phase Bonding Research Articles

Transient Liquid Phase Bonding of ZGH451 Superalloy Fabricated by Directed Energy Deposition

ZGH451, a directionally solidified Ni‐based superalloy designed for additive manufacturing, has garnered significant attention in the realm of next‐generation turbine blades. Welding the ZGH451 superalloy is crucial for promoting its practical application. In this study, transient liquid phase (TLP) bonding is applied to weld ZGH451 superalloy produced through directed energy deposition. A Ni‐based interlayer alloy powder is developed and prepared via thermodynamic calculation, with the interlayer subsequently characterized using differential thermal analysis. TLP bonding is conducted at 1200 °C for 4 h. The influence of the preset gap on the joint microstructure and mechanical properties is examined. The microstructure of the TLP bonding joints comprises athermally solidified zones (ASZ), isothermally solidified zones, and diffusion‐affected zones. The ASZ width significantly increases with the growing preset gap. A preset gap not exceeding 100 μm enables complete isothermal solidification of the joints. Particularly, joints with a preset gap ranging from 0 to 30 μm demonstrate optimal reliability, exhibiting a tensile strength of up to 1375 MPa at room temperature, which is 12% higher than the room temperature strength of the base metal (BM), and a tensile strength of 983 MPa at 760 °C, surpassing 86% of the BM's strength at the same temperature.

Transient Liquid Phase Bonding by Two-Step Heating Technique of IN939

Transient Liquid Phase Bonding by Two-Step Heating Technique of IN939

The Effect of Bonding Time and Temperature on Microstructure and Mechanical Properties of SS316L/WC-Co Dissimilar Joint Produced by Transient Liquid Phase Bonding

The Effect of Bonding Time and Temperature on Microstructure and Mechanical Properties of SS316L/WC-Co Dissimilar Joint Produced by Transient Liquid Phase Bonding

Cu array fabrication: An environmentally sustainable approach through bicontinuous microemulsion differential electrodeposition for advanced power device packaging

BackgroundThe demand for high-power density packaging and integration processes for third-generation semiconductors, like silicon carbide (SiC), necessitates advancements beyond conventional Si-based packaging technologies. Cu-Cu direct bonding emerges as a promising alternative in semiconductor packaging. However, achieving Cu-to-Cu direct bonding with low-temperature, low-pressure, and short-time poses significant challenges. Transient Liquid Phase Bonding (TLP) offers a low-temperature joining solution, but prolonged reflow time hinders its wide applications. MethodsThis study introduces a novel strategy utilizing bicontinuous microemulsion (BME) electrodeposition to fabricate micron-sized Cu arrays, addressing these challenges in achieving Cu bonding. The core of Cu array manufacturing lies in the differential electrodeposition rate of Cu ions in the aqueous and organic phases. This principle is rooted in the excellent conductivity of the aqueous solution compared to the non-conductivity of the organic solution. Significant findingsWe elucidate the growth mechanism and validate a theory for achieving void-free optimal growth of Cu arrays within BME and compared the cross-sectional morphology and fracture modes of TLP solder joints with micron and nano Cu arrays. Furthermore, the ability to recycle the BME soft template aligns with green chemistry principles, offering a sustainable die-attach approach for third-generation semiconductor device packaging.

Transient Liquid Phase Bonding with Sn-Ag-Co Composite Solder for High-Temperature Applications

In this study, a novel composite solder, Sn-3.5Ag-10.0Co, was tailored for transient liquid phase (TLP) bonding in electric vehicle power module integration. Employing a meticulous two-step joining process, the solder joint was transformed into a robust microstructure characterized by two high-melting point intermetallic compounds, Ni3Sn4 and (Co,Ni)Sn2. After 1 h of TLP bonding, the Sn-3.5Ag-10.0Co paste transformed into the IMCs, but voids persisted between them, particularly between (Co,Ni)Sn2 and Ni3Sn4. Voids significantly reduced after 2 h of bonding, with full coalescence of the joint microstructure observed. The joint continued to be densified after 3 h of TLP bonding, but voids tended to accumulate at the joint center. Failure analysis revealed crack propagation through Ni3Sn4/(Co,Ni)Sn2 interfaces and internal voids. The engineered Sn-Ag-Co TLP joint exhibited superior shear strength retention even at an elevated temperature of 200 °C, contrasting with the significant reduction observed in the Sn-3.5Ag control specimen due to remaining Sn.

A study on the thermomechanical response of various die attach metallic materials of power electronics

PurposeIn power electronics, there are various metallic material systems used as die attachments. The complete understanding of the thermomechanical behavior of such interconnections is very important. Therefore, this paper aims to examine the thermomechanical response of four famous die attach materials, including sintered silver, sintered nano-copper particles, gold-tin solders and silver-tin transient liquid phase (TLP) bonds, using nonlinear finite element analysis.Design/methodology/approachDuring the study, the mechanical properties of all die attach systems, including elastic and viscoplasticity parameters, are obtained from literature studies and hence incorporated into the numerical analysis. Subsequently, the bond stress–strain relationships, stored inelastic strain energies and equivalent plastic strains are thoroughly examined.FindingsThe results showed that the silver-tin TLP bonds are more likely to develop higher inelastic strain energy densities, while the sintered silver and copper interconnects would possess higher plastic strains and deformations. Suggesting higher damage to such metallic die attachments. The expensive gold-based solders have developed least inelastic strain energy densities and least plastic strains as well. Thus, they are expected to have improved fatigue performance compared to other bonding configurations.Originality/valueThis paper extensively investigates and compares the mechanical and thermal response of various metallic die attachments. In fact, there are no available research studies that discuss the behavior of such important die attachments of power electronics when exposed to mechanical and thermomechanical loads.

Research on the creep response of lead-free die attachments in power electronics

PurposeThe purpose of this paper is to investigate the thermomechanical response of four well-known lead-free die attach materials: sintered silver, sintered nano-copper particles, gold-tin solders and silver-tin transient liquid phase (TLP) bonds.Design/methodology/approachThis examination is conducted through finite element analysis. The mechanical properties of all die attach systems, including elastic and Anand creep parameters, are obtained from relevant literature and incorporated into the numerical analysis. Consequently, the bond stress-strain relationships, stored inelastic strain energies and equivalent plastic strains are thoroughly examined.FindingsThe results indicate that silver-tin TLP bonds are prone to exhibiting higher inelastic strain energy densities, while sintered silver and copper interconnects tend to possess higher levels of plastic strains and deformations. This suggests a higher susceptibility to damage in these metallic die attachments. On the other hand, the more expensive gold-based solders exhibit lower inelastic strain energy densities and plastic strains, implying an improved fatigue performance compared to other bonding configurations.Originality/valueThe utilization of different metallic material systems as die attachments in power electronics necessitates a comprehensive understanding of their thermomechanical behavior. Therefore, the results of the present paper can be useful in the die attach material selection in power electronics.

Joined AZ31B Magnesium Alloys with Ag Interlayer by Ultrasonic-Induced Transient Liquid Phase Bonding in Air

Joined AZ31B Magnesium Alloys with Ag Interlayer by Ultrasonic-Induced Transient Liquid Phase Bonding in Air

Towards a self-healing aluminum metal matrix composite: Design, fabrication, and demonstration

This paper presents a novel approach to designing and synthesizing a self-healing aluminum-based metal matrix composite (MMC) at the macro-scale. The composite comprises an Al 5083 matrix embedded with low melting point particles (LMPPs) that act as healing agents. A two-step electroless micro-encapsulation process is developed to create LMMPs with a diffusion and thermal barrier designed to protect the Zn-8Al core with a Co-P shell. The MMC is fabricated using spark plasma sintering. Following controlled total fracture under tension, external compressive force is applied during heat treatment to heal the fracture effectively. The evolution of phases and interfaces is characterized using electron microscopy, and transient liquid phase bonding (TLPB) is identified as the fracture-healing mechanism, facilitated in areas with sufficiently high Zn concentration to fill the crack. The design can be expanded to incorporate other matrix and LMMP materials, mechanical crack volume reduction by integrating shape memory alloy (SMA) reinforcement during MMC synthesis, and processing of the self-healing MMC using Directed Energy Deposition additive manufacturing.

Interfacial intermetallic compounds growth kinetics and mechanical characteristics of Ga-Cu interconnects prepared via transient liquid phase bonding

Driven by continuous miniaturization, higher performance, and functional robustness in three-dimensional (3D) embodiments of electronic devices, Ga which possesses a low melting point (29.8°C) has shown its potential uses in electronics packaging and integration. The use of Ga metal as a solder material to achieve low-temperature transient liquid phase bonding (TLPB) has emerged as a viable solution for reliable interconnections of future-generation products. This study investigates the interfacial intermetallic compounds (IMCs) structure, growth kinetics, and mechanical characteristics of Ga-Cu TLPB joints in the temperature range of 150–220°C. The Cu9Ga4 phase were observed and the growth rate of Ga-Cu IMCs has been investigated. The research findings indicate that the growth mechanism of interface IMCs is primarily diffusion-controlled, with CuGa2 grains exhibiting anisotropic growth. Their shear strength has reached 23.8 MPa, with a porosity of 1.82±0.07%. Furthermore, the fracture interface is presented and correlated with the experimental observations.

Anand constitutive modeling of multilayer Silver-Tin transient liquid phase foils using tensile and creep testing

Purpose This paper aims to present two Anand’s model parameter sets for the multilayer silver–tin (AgSn) transient liquid phase (TLP) foils. Design/methodology/approach The AgSn TLP test samples are manufactured using pre-defined optimized TLP bonding process parameters. Consequently, tensile and creep tests are conducted at various loading temperatures to generate stress–strain and creep data to accurately determine the elastic properties and two sets of Anand model creep coefficients. The resultant tensile- and creep-based constitutive models are subsequently used in extensive finite element simulations to precisely survey the mechanical response of the AgSn TLP bonds in power electronics due to different thermal loads. Findings The response of both models is thoroughly addressed in terms of stress–strain relationships, inelastic strain energy densities and equivalent plastic strains. The simulation results revealed that the testing conditions and parameters can significantly influence the values of the fitted Anand coefficients and consequently affect the resultant FEA-computed mechanical response of the TLP bonds. Therefore, this paper suggests that extreme care has to be taken when planning experiments for the estimation of creep parameters of the AgSn TLP joints. Originality/value In literature, there is no constitutive modeling data on the AgSn TLP bonds.

Controlling Pore Position during Transient Liquid Phase Bonding for High-temperature Soldering Processes

Controlling Pore Position during Transient Liquid Phase Bonding for High-temperature Soldering Processes

Investigations of selected influencing process factors for transient liquid phase soldering (TLPS) as a die-attach method for automotive power modules

Increasing the operating temperatures in power electronic applications cause a decreasing lifetime of the die-attach interconnection. Transient liquid phase soldering (TLPS) is able to create a reliable and high temperature resistant connection layer via diffusion processes in the form of intermetallic phases with melting points up to > 400°C. This study concentrates on a TLPS reflow-soldering process with a tin-copper-tin (Sn-Cu-Sn) layered preform. During the soldering process the influence of the selected process parameters for the Sn-Cu-Sn on the grown intermetallic phase interconnections between the preform and the components are investigated via the average void percentage and a process capability analysis (cpK). The application of mechanical pressure decreases the average void percentage below 10%. Due to the lower average void percentage the influence of the holding time, peak temperature and heating gradient are examined under low pressure. The biggest impact shows the heating gradient. With a slow heating gradient, the thermomechanical stress decreases by increasing the solubility and the average void percentage could be reduced to less than 2.7 %. In combination of the optimized selected process factors it is possible to reach a process capability value of 1.

Cu-Cu joint with Sn-58Bi/Porous Cu/Sn-58Bi transient liquid phase bonding under formic acid atmosphere

PurposeThis paper aims to examine the effects of bonding temperature, bonding time, bonding pressure and the presence of a Pt catalyst on the bonding strength of Cu/SB/P-Cu/SB/Cu joints by transient liquid phase bonding (TLPB).Design/methodology/approachTLPB is promising to assemble die-attaching packaging for power devices. In this study, porous Cu (P-Cu) foil with a distinctive porous structure and Sn-58Bi solder (SB) serve as the bonding materials for TLPB under a formic acid atmosphere (FA). The high surface area of P-Cu enables efficient diffusion of the liquid phase of SB, stimulating the wetting, spreading and formation of intermetallic compounds (IMCs).FindingsThe higher bonding temperature decreased strength due to the coarsening of IMCs. The longer bonding time reduced the bonding strength owing to the coarsened Bi and thickened IMC. Applying optimal bonding pressure improved bonding strength, whereas excessive pressure caused damage. The presence of a Pt catalyst enhanced bonding efficiency and strength by facilitating reduction–oxidation reactions and oxide film removal.Originality/valueOverall, this study demonstrates the feasibility of low-temperature TLPB for Cu/SB/P-Cu/SB/Cu joints and provides insights into optimizing bonding strength for the interconnecting materials in the applications of power devices.

Effects of Transient Liquid Phase Bonding Time on Microstructure, Mechanical and Corrosion Properties During Bonding of Inconel 617/AISI 310 Stainless Steel

Effects of Transient Liquid Phase Bonding Time on Microstructure, Mechanical and Corrosion Properties During Bonding of Inconel 617/AISI 310 Stainless Steel

Transient liquid phase bonding assisted spark plasma sintering of La-Fe-Si magnetocaloric bulk materials

The poor mechanical properties of La-Fe-Si based alloys restrict the potential of these magnetocaloric materials. Hence, a novel transient liquid phase bonding (TLPB) processing technique was deployed during spark plasma sintering (SPS) of La-Fe-Si based bulk materials. A series of binder-free LaFe11.8Si1.2 bulk materials were prepared by SPS and hot-pressing sintering (HPS). Transient melting, which occurred during SPS, accelerated the decomposition of the 1:13 phase, resulting in low porosity and high strength. Compared to HPS samples, SPS samples have significantly larger maximum compressive strength (σbc)max of ∼637.9 MPa at a strain of 4.7%, good thermal conductivity of ∼7.6 W·m−1·K−1 at 300 K, and a large (−ΔSM)max value of ∼11.7 J·kg−1·K−1 at TC= 193 K under a magnetic field change of 0 − 5 T. Thus, binder-free La-Fe-Si based bulk magnetocaloric materials with an excellent property set have been successfully prepared by TLPB assisted SPS technology.

Retaining multi-oriented and fine grain structure with Ni doping in Cu/Sn-3.0Ag-0.5Cu/Cu transient liquid phase bonding under isothermal aging treatment

Transient liquid phase bonding has been proven to offer exceptional joining strength and dependable high temperature service in chip stacking applications. Nevertheless, conventional Cu/Sn/Cu transient liquid phase bumps had shortcomings, such as smooth phase boundaries and coarsening grains. In this study, the variation of microstructure in Cu/Sn-3.0Ag-0.5Cu/Cu, Cu/Sn-3.0Ag-0.5Cu/Ni, and Ni/Sn-3.0Ag-0.5Cu/Cu transient liquid phase bonds with the sizes less than 10 μm before and after long term aging were investigated. Due to the dissolution of Ni atoms from the substrates at the cold or hot end, the structure exhibited randomly-oriented and small-sized grains. After 1000 h aging treatment, the Ni-containing specimen still retained the abundant grain structure and appeared network-like morphology of Cu3Sn near phase boundaries. Additionally, the shear testing was applied in the aged samples, Ni-doped joints demonstrated better mechanical properties than Ni-free joining. The enhancement of shear strength was attributed to Ni addition, retaining the advantageous grain structure. This present work showed that doping Ni to micro-bumps could halt the deterioration of grain structure over extended usage of electronic devices in 3D-IC technology.

Microstructure and Shear properties of Sn–xZn Transient Liquid Phase Bonding in 3D-Chip Stacking Packaging

Microstructure and Shear properties of Sn–xZn Transient Liquid Phase Bonding in 3D-Chip Stacking Packaging

High temperature shear and thermal aging behavior of dissimilar transient liquid phase bonded Hastelloy X to Ni3Al intermetallic compound

Nickel super alloys and intermetallic compounds (IMCs) are candidate as strategic materials for turbine industry, because of its excellent high temperature properties. In this study, mechanical properties and thermal aging behavior (post thermal exposure) of the transient liquid phase (TLP) bonds between Hastelloy X to Ni3Al IMC at temperature range of 800–900 °C were investigated. The microstructure and fracture surfaces of the joints were examined by optical and scanning electron microscopes as well as XRD analysis. The optimum joint bonding strength was achieved for the sample treated at 1100 °C–180 min equaling to 355 ± 4.5 MPa. XRD patterns of semi-cleavage fracture surfaces revealed nickel solid solution matrix containing BNi3 and Ni3Si compounds generated at ASZ/ISA interface. The ultimate tensile strength reaches 36.5 ± 1 and 20.5 ± 1 MPa at temperatures of 800 °C and 900 °C, respectively. Fracture occurred in the IMC substrates for both temperatures were due to shrinkage porosity during solidification of IMC and mismatch of crystal lattice constants with the matrix. The thermal aging process at 900 °C for 50–500 h had a minor effect on the joint microstructure but generated TCP phases in the Hastelloy X.

Laminated transient liquid phase preform and bond characterization for high-temperature power electronics application

Laminated transient liquid phase preform and bond characterization for high-temperature power electronics application