Modeling Transient Liquid Phase Bonding Process In The Ni P System

A new finite difference numerical model with variable diffusion coefficient is developed by using an explicit-fully-implicit hybrid method and Landau transformation with adaptable spatial discretization to study TLP bonding kinetics in planar and non-planar systems. The results of the numerical model developed in this research, which are verified with experimental data available in the literature, reveal key reasons for why the extent of isothermal solidification deviates from linear relationship with √t, i.e. deviation from parabolic behavior. The deviation occurs when the concentration dependency of D changes with time. In non-planar systems (cylindrical and spherical), however, deviation from the parabolic behavior can occur even when D is independent of both concentration and time, solely by geometry-induced effect. Moreover, the kinetics of solute penetration into the substrate during isothermal solidification is different from the solute penetration kinetics that occur during homogenization process that follows the isothermal solidification stage.

Joining Processes is aimed at scientists and engineers who need to specify effective means of joining metals and ceramics, and also for undergraduates whose studies encompass joining processes. Joining Processes provides a brief review of the spectrum of joining processes ranging from fusion welding to adhesive bonding, followed by a detailed introduction to brazing, diffusion bonding and their hybrid processes. This book also describes the scientific principles of the joining processes and provides practical information about the optimum selection of joining materials, joint designs and processing parameters. The effects of both similarities and significant differences of the processes on joint properties are emphasised and illustrated by descriptions of case histories of successful applications.

Provides in-depth knowledge on novel materials that make electronics work under high-temperature and high-pressure conditions This book reviews the state of the art in research and development of lead-free interconnect materials for electronic packaging technology. It identifies the technical barriers to the development and manufacture of high-temperature interconnect materials to investigate into the complexities introduced by harsh conditions. It teaches the techniques adopted and the possible alternatives of interconnect materials to cope with the impacts of extreme temperatures for implementing at industrial scale. The book also examines the application of nanomaterials, current trends within the topic area, and the potential environmental impacts of material usage. Written by world-renowned experts from academia and industry, Harsh Environment Electronics: Interconnect Materials and Performance Assessment covers interconnect materials based on silver, gold, and zinc alloys as well as advanced approaches utilizing polymers and nanomaterials in the first section. The second part is devoted to the performance assessment of the different interconnect materials and their respective environmental impact. -Takes a scientific approach to analyzing and addressing the issues related to interconnect materials involved in high temperature electronics -Reviews all relevant materials used in interconnect technology as well as alternative approaches otherwise neglected in other literature -Highlights emergent research and theoretical concepts in the implementation of different materials in soldering and die-attach applications -Covers wide-bandgap semiconductor device technologies for high temperature and harsh environment applications, transient liquid phase bonding, glass frit based die attach solution for harsh environment, and more -A pivotal reference for professionals, engineers, students, and researchers Harsh Environment Electronics: Interconnect Materials and Performance Assessment is aimed at materials scientists, electrical engineers, and semiconductor physicists, and treats this specialized topic with breadth and depth.

A new numerical model that can be used to study the kinetics of temperature gradient transient liquid phase (TG -TLP) bonding under concentration-dependent diffusivity has been developed by using a first-order implicit-explicit numerical method, and Landau coordinate transformation with adaptable spatial discretization. A number of non-trivial assumptions that reduce accuracy are avoided and the model is validated with experimental data reported in the literature. In contrast to previously reported findings, the results of this new model show that solid-state diffusion plays a significant role, not only in controlling the transition in solidification behavior from bidirectional to unidirectional, but also affects the kinetics of the bonding process. Previous reports have stated that TG-TLP bonding always produces a shorter bonding completion time compared to the conventional transient liquid phase bonding (C -TLP) due to a higher solute diffusivity in the liquid compared to the solid. However, the results in this work show that the concentration gradient in the liquid is the major factor that enhances the solidification kinetics in TG -TLP bonding to produce shorter bonding time. Furthermore, in C -TLP bonding, increase in temperature above a specific threshold temperature can result in a longer bonding completion time. However, a detailed analysis in this study shows that this undesirable behaviour can be prevented in TG -TLP bonding, if the concentration gradient in the liquid facilitates adequate solidification kinetics to overcome the increased liquid volume that normally accompanies increased bonding temperature. Finally, it is often assumed that during TG-TLP bonding, after the commencement of unidirectional solidification, which helps to produce desirable directionally solidified single crystal joint, the solidification mode occurs persistently till the end of the bonding process. Nevertheless, the analysis performed in this work shows that the occurrence of unidirectional solidification during TG -TLP bonding can be compromised, by reverting to bidirectional solidification, if a single heat source is used to impose the temperature gradient, depending on the location of the heat source relative to the joint region.

This text provides a comprehensive overview of the technology surrounding the brazing process to allow the inexperienced engineer, student or professional, to utilize fully this technology.