Search Results for microelectronic welds

Ultrasonic metal welding is a solid-state welding process that produces coalescence through the simultaneous application of localized high-frequency vibratory energy and moderate clamping forces. This article discusses the parameters to be considered when selecting a suitable welder for ultrasonic metal welding. It details the personnel requirements, advantages, limitations, and applications, namely, wire welds, spot welds, continuous seam welds, and microelectronic welds of ultrasonic metal welding.

This article begins with a discussion on the advantages and limitation of ultrasonic welding (USW). It describes variations of the USW process which can produce different weld geometries. These variations are helpful in producing spot welds, line welds, continuous seam welds, ring welds, and microelectronic welds. The article provides information on the functions of USW personnel and describes the special conditions in USW which include the condition of the surface, the use of an interlayer, and the control of resonance. It concludes with a description on the weld quality, the influencing factors, surface appearance and deformation, and metallographic examination.

This article discusses the influence of the materials, design, package type, and environment on corrosion in microelectronics. It describes the common sources and mechanisms of corrosion in microelectronics, including anodic, cathodic, and electrolytic reactions resulting in uniform corrosion, galvanic corrosion, pitting corrosion, creep corrosion, dendrite growth, fretting, stress-corrosion cracking, and whisker growth. The article presents effective measures for minimizing the moisture retention in hermetic packages and/or moisture ingress in plastic packages. It concludes with information corrosion tests.

Joining is key to the manufacture of large or complex devices or assemblies; construction of large and complex structures; and repair of parts, assemblies, or structures in service. This article describes the three forces for joining: physical, chemical, and mechanical. It provides an overview of the joining processes, namely, mechanical fastening, integral attachment, adhesive bonding, welding, brazing, and soldering. The article concludes with information on the various aspects of joint design and location that determine the selection of a suitable joining method.

This article provides a history of electron and laser beam welding, discusses the properties of electrons and photons used for welding, and contrasts electron and laser beam welding. It presents a comparison of the electron and laser beam welding processes. The article also illustrates constant power density boundaries, showing the relationship between the focused beam diameter and the absorbed beam power for approximate regions of keyhole-mode welding, conduction-mode welding, cutting, and drilling.

Ultrasonic welding (UW), as a solid-state joining process, uses an ultrasonic energy source and pressure to induce oscillating shears between the faying surfaces to produce metallurgical bonds between a wide range of metal sheets and wires. This article reviews the models of the ultrasonic welding with an emphasis on governing equations, material behavior, and heat generation of the process. It discusses the resulting factors, namely, vibration, friction, temperature, and plastic deformation as well as the bonding strength and its mechanism.

Microjoining methods are commonly used to fabricate medical components and devices. This article describes key challenges involved during microjoining of medical device components. The primary mechanisms used in microjoining for medical device applications include microresistance spot welding (MRSW) and laser welding. The article illustrates the fundamental principles involved in MRSW and laser welding. The article presents examples of various microjoining methods used in medical device applications, including pacemaker and nitinol microscopic forceps.

Three types of energy are used primarily as direct heat sources for fusion welding: electric arcs, laser beams, and electron beams. This article reviews the physical phenomena that influence the input-energy distribution of the heat source for fusion welding. It also discusses several simplified and detailed heat-source models that have been used in the modeling of arc welding, high-energy-density welding, and resistance welding.

Microjoining with high energy density beams is a new subject in the sense that the progress of miniaturization in industry has made the desire to make microjoints rapidly and reliably a current and exciting topic. This article summarizes the current state of microjoining with both electron and laser beams. It considers the elementary physical processes such as heat and fluid flow to introduce the reader to the phenomena that affect melting, coalescence, and solidification needed for a successful microweld. The various forces driving (and resisting) fluid flow are analyzed. The article discusses the equipment suitable for microjoining and the metallurgical consequences and postweld metrology of the process. It also provides examples of developmental welds employing laser and electron beam microwelding techniques.

This article discusses different types of joining processes, including welding, brazing, soldering, mechanical fastening, and adhesive bonding. It examines two broad classes of welding: fusion welding and solid-state welding. The article discusses the process selection considerations for welding, brazing, and soldering. It also describes joint design considerations such as selection of weld joints and welds.

Coatings and other surface modifications are used for a variety of functional, economic, and aesthetic purposes. Two major applications of thermal spray coatings are for wear resistance and corrosion resistance. This article discusses thermal (surface hardening) and thermochemical (carburizing, nitriding, and boriding) surface modifications, electrochemical treatments (electroplating, and anodizing), chemical treatments (electroless plating, phosphating, and hot dip coating), hardfacing, and thermal spray processes. It provides information on chemical and physical vapor deposition techniques such as conventional CVD, laser-assisted CVD, cathodic arc deposition, molecular beam epitaxy, ion plating, and sputtering.

Laser-ultrasonics is a particular implementation of ultrasonic nondestructive inspection in which ultrasound is generated and detected by lasers. This article discusses the various mechanisms that ensure ultrasound generation and explains the possibility to get the equivalent of phase-array by numerical processing of an array of previously acquired laser-ultrasonic signals. The article describes the ultrasound generation by thermoelastic mechanism and ablation or vaporization. It illustrates the principle of optical detection of ultrasound with confocal Fabry-Perot interferometer and photorefractive two-wave mixing interferometer. The article concludes with information on the industrial applications of laser-ultrasonics, including thickness measurement, flaw detection, and material characterization.

This article provides information on the development of finite element analysis (FEA) and describes the general-purpose applications of FEA software programs in structural and thermal, static and transient, and linear and nonlinear analyses. It discusses special-purpose finite element applications in piping and pressure vessel analysis, impact analysis, and microelectronics. The article describes the steps involved in the design process using the FEA. It concludes with two case histories that involve the use of FEA in failure analysis.

When complex designs, transient loadings, and nonlinear material behavior must be evaluated, computer-based techniques are used. This is where the finite-element analysis (FEA) is most applicable and provides considerable assistance in design analysis as well as failure analysis. This article provides a general view on the applicability of finite-element modeling in conducting analyses of failed components. It highlights the uses of finite-element modeling in the area of failure analysis and design, with emphasis on structural analysis. The discussion covers the general development and both general- and special-purpose applications of FEA. The special-purpose applications of FEA covered are piping and pressure vessel analysis, impact analysis, and microelectronic and microelectromechanical systems analysis. The article provides case histories that involved the use of FEA in failure analysis.

This article focuses on the various types of corrosion-related failure mechanisms and their effects on passive electrical components. The types include halide-induced corrosion, organic-acid-induced corrosion, electrochemical metal migration, silver tarnish, fretting, and metal whiskers. The passive electrical components include resistors, capacitors, wound components, sensors, transducers, relays, switches, connectors, printed circuit boards, and hardware.

Metals and alloy powders are used in welding, hardfacing, brazing, and soldering applications, which include hardface coatings, the manufacturing of welding stick electrodes and flux-cored wires, and additives in brazing pastes or creams. This article reviews these applications and the specific powder properties and characteristics they require.

This article explores the possibilities and limitations imposed by manufacturing processes and materials. Detailed design rules for the processes are presented. The article lists the main features of process groups in a tabular form. The physical characteristics and ratings of relative cost and production factors are also tabulated. The process groups include casting; deformation; powder processing; machining; noncutting; joining; ceramic, glass, and polymer processing; and composites manufacturing.

Microstructural analysis is the combined characterization of the morphology, elemental composition, and crystallography of microstructural features through the use of a microscope. This article reviews three types of the most commonly used electron microscopies in metallurgical studies, namely scanning electron microscopy, electron probe microanalysis, and transmission electron microscopy. It briefly describes the operating principles, instrumentation which includes energy dispersive X-ray detectors, spatial resolution, typical use of the techniques, elemental analysis detection threshold and precision, limitations, sample requirements, and the capabilities of related techniques.