Transient Liquid Phase Research Articles

Evaluation of high-temperature long-term reliability of transient liquid phase bonded joints using etched Cu foam/Sn–3.0Ag–0.5Cu composite solder preform

Evaluation of high-temperature long-term reliability of transient liquid phase bonded joints using etched Cu foam/Sn–3.0Ag–0.5Cu composite solder preform

Time-dependent effects in transient liquid phase bonding of 304L and Cp-Ti using an Ag-Cu interlayer

Time-dependent effects in transient liquid phase bonding of 304L and Cp-Ti using an Ag-Cu interlayer

Transient liquid phase bonding method of SnIn for high-temperature packaging

Transient liquid phase bonding method of SnIn for high-temperature packaging

Synergistic Tailoring of Electronic and Thermal Transports in Thermoelectric Se-Free n-Type (Bi,Sb)2Te3.

Se-free n-type (Bi,Sb)2Te3 thermoelectric materials, outperforming traditional n-type Bi2(Te,Se)3, emerge as a compelling candidate for practical applications of recovering low-grade waste heat. A 100% improvement in the maximum ZT of n-type Bi1.7Sb0.3Te3 is demonstrated by using melt-spinning and excess Te-assisted transient liquid phase sintering (LPS). Te-rich sintering promotes the formation of intrinsic defects (TeBi), elevating the carrier concentration and enhancing the electrical conductivity. Melt-spinning with excess Te fine-tunes the electronic band, resulting in a high power-factor of 0.35 × 10-3 W·m-1 K-2 at 300 K. Rapid volume change during sintering induces the formation of dislocation networks, significantly suppressing the lattice thermal conductivity (0.4 W·m-1 K-1). The developed n-type legs achieve a high maximum ZT of 1.0 at 450 K resulting in a 70% improvement in the output power of the thermoelectric device (7.7 W at a temperature difference of 250 K). This work highlights the synergy between melt-spinning and transient LPS, advancing the tailored control of both electronic and thermal properties in thermoelectric technology.

Microstructure and mechanical properties of transient liquid phase bonding Ti3SiC2 ceramic to SUS430 steel using an Al interlayer

Microstructure and mechanical properties of transient liquid phase bonding Ti3SiC2 ceramic to SUS430 steel using an Al interlayer

Investigation on microstructure and mechanical properties of GH5188 superalloy TLP joints using nickel based alloy interlayer

GH5188 was bonded successfully with a commercial BNi-2 interlayer through transient liquid phase (TLP) diffusion bonding. The characteristic bonded joint was formed by following three characteristic zones: diffusion affected zone (DAZ) mainly consisting of boride precipitates, athermal solidification zone (ASZ) composed of multiple silica-boride phases and isothermal solidification zone (ISZ) containing γ solid solution phases. As the holding time increases, ISZ gradually replaced ASZ and a defect-free joints was obtained then. However, excessive holding time can cause ASZ to reappear because of the extravagant dissolution of the base metal. The joints’ shear strength from 574 MPa (1190 °C/5 min) increased to 777 MPa (1190 °C/60 min), and the fracture location shifted from ASZ to DAZ with the fracture mode transferred from cleavage fracture to mixed fracture.

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.

The role of γ-C 2H 5NO 2 as a new transient liquid phase in cold sintering process of BaTiO 3 composites

The role of γ-C ₂H ₅NO ₂ as a new transient liquid phase in cold sintering process of BaTiO ₃ composites

Cold sintering preparation of B4C@SiO2/20BP ceramic matrix composite and its dry tribological properties

To achieve low-temperature sintering of B4C ceramic, 'sol-gel' method is employed to create a B4C@SiO2 core-shell structure composite. Black phosphorus (BP) is exfoliated through 3 methods to obtain few-layer black phosphorene (FLBP) with sizes ranging from 100 µm to 1 µm. B4C@SiO2/20BP composite is successfully prepared through cold sintering process at 3 GPa and 90 °C, using NaOH solution as the transient liquid phase. The dry friction properties of B4C@SiO2/20BP composites with different sizes of FLBP are investigated in a ball-on-disc contact form. The findings reveal that as the FLBP size decreases, the friction coefficient gradually increases, inversely correlating with the wear rate. The wear mechanism shifts from adhesive wear to fatigue wear, leading to a diminishing anti-friction effect of FLBP.

Effects of Cu/SnAgCu Powder Fraction and Sintering Time on Microstructure and Mechanical Properties of Transient Liquid Phase Sintered Joints.

The effects of the sintering duration and powder fraction (Ag-coated Cu/SnAgCu) on the microstructure and reliability of transient liquid phase sintered (TLPS) joints are investigated. The results show that two main intermetallic compounds (IMCs, Cu6Sn5 and Cu3Sn) formed in the joints. The Cu6Sn5 ratio generally decreased with increasing sintering time, Cu powder fraction, and thermal treatment. The void ratio of the high-Cu-fraction joints decreased and increased with increasing sintering and thermal stressing durations, respectively, whereas the low-Cu-fraction counterparts were stable. We also found that the shear strength increased with increasing thermal treatment time, which resulted from the transformation of Cu6Sn5 and Cu3Sn. Such findings could provide valuable information for optimizing the TLPS process and assuring the high reliability of electronic devices.

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

Effect of Bonding Time, Composition of Interlayer, and Postbond Heat Treatment on Transient Liquid Phase Joints of Inconel 718 Superalloy

The investigation aims to explore the relationship between the microstructure and mechanical properties of transient liquid phase‐bonded joints of Inconel 718 (IN718) nickel‐based superalloy, utilizing BNi‐1 and BNi‐2 interlayers with a thickness of 50 μm, produced at 1150 °C for varying durations. Microstructural analysis, facilitated by scanning electron microscopy, and phase analysis, utilizing energy‐dispersive spectrometer, reveal a diverse range of microstructures, including continuous eutectic intermetallic phases and eutectic‐free configurations under different bonding conditions. Additionally, the interfacial diffusion of IN718/BNi‐2 is simulated by molecular dynamics. Notably, higher mass fractions of Cr in the interlayer are found to prolong the time of isothermal solidification. The use of BNi‐2 interlayers, 50 μm in thickness, results in joints achieving isothermal solidification within a remarkably brief 10 min, a significantly shorter duration compared to previous studies. Mechanical tests, encompassing microhardness and uniaxial tensile experiments, are carried out on all samples. The microhardness of the isothermally solidified zone decreases with increasing bonding time. The tensile strength of bonded joints increases with extended bonding time before isothermal solidification completion, followed by a subsequent decline. The highest tensile strength (893.3 MPa) is observed in joints using BNi‐2 interlayer after applying postbond heat treatment, representing approximately 88.5% of the base metal tensile strength.

Kinetics of initial diffusion solidification during continuous heating in term of IN718 superalloy / 316LN steel TLP bonding system

In this work, the effect of heating rate on the solidification kinetics of the dissimilar transient liquid phase (TLP) bonding joint of IN718 superalloy / 316LN steel was investigated. It was determined that the initial diffusion solidification (IDS) during continuous heating, accompanied by the melting of interlayer, plays an important role on the formation of TLP bonding joint. The lower heating rate results in the more sufficient IDS and thus the shorter time needed for isothermal solidification. This overturns the conventional view that the solidification behavior in TLP bonding joints mainly occurs at the stage of isothermal holding. Additionally, the IDS process is modeled using diffusion-based concepts under varying heating rates. The proposed model is more applicable for the prediction of solidification time in TLP bonding joint than the classic models only on the consideration of isothermal solidification.

Understanding the formation mechanism of SiC/Al joints by U-TLP bonding with the inactive Zn interlayer

The ultrasonic-assisted transient liquid phase (U-TLP) bonding process is extremely fast, which is a great challenge to reveal the inherent mechanisms. Understanding the joint formation mechanism of U-TLP is essential for the joining process design. In this study, the SiC ceramics and 6063Al alloys were joined by U-TLP using a Zn interlayer. The process of removing the oxide film on the base metal involved cracking, flaking off, suspending, and fragmenting. The migration of the eutectic liquid phases frontier was very fast (within 1 s). The relationship between the thickness of the liquid layer and the ultrasonic action time was a power function. The typical microstructure of the SiC/6063Al joints was SiC/amorphous Al2O3/Zn-Al eutectic/ Zn-Al eutectoid/6063Al. The shear strength of SiC/6063Al joints increased with the interfacial bonding ratio and reached up to 27 MPa for the ultrasonic action time of 5 s. The metallurgical bonding at the SiC/bond metal interface was formed through the amorphous Al2O3 transition layer. The formation mechanism of the Al2O3 reaction layer was revealed based on the thermodynamics, kinetics, and acoustics cavitation theory. This will provide a guideline for the future U-TLP process design.

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.

Microstructure evolution and mechanical properties of Cu-Ni-Ti transient liquid phase bonding for SiC-GH3536 joints

In this study, transient liquid-phase (TLP) bonding of SiC and GH3536 was employed using Cu80Ti15Ni5 (at%) mixed powder. The melting characteristics of the filler materials were analyzed, and the influence of holding time on the microstructure and mechanical properties of the joints was investigated. The formation mechanism of the joints was also explored. The results indicate that the filler materials completely melted at 970°C. In the liquid filler materials, high-melting-point intermetallic compounds (IMCs) can be formed in situ, thereby consuming the melting-point depressant element Ti. Isothermal solidification of the joints was achieved in a short period, and the joint consists of a Cu(ss) matrix and partial (CuₓNi1-x)2Ti ternary compounds and silicides. Cu(ss) exhibits good plasticity, and the in-situ generated (CuxNi1-x)2Ti helps reduce the coefficient of thermal expansion (CTE) of the joints. Therefore, the joining layer has a beneficial effect in alleviating residual stresses. After holding at 970°C for 15 minutes, the maximum shear strength reached 56.25 MPa. This work provides a new method for joining SiC ceramics and their composites with nickel-based alloys, offering innovative insights into the bonding of ceramics with metals.

Correction: Effects of Homogenization Heat Treatment on Microstructure, Mechanical and Corrosion Properties of Transient Liquid Phase (TLP)-Bonded Inconel 617/AISI 310 Stainless Steel

Correction: Effects of Homogenization Heat Treatment on Microstructure, Mechanical and Corrosion Properties of Transient Liquid Phase (TLP)-Bonded Inconel 617/AISI 310 Stainless Steel