The need for precise targeted interactive surgery on boards or modules is the main driver of backside preparation technology. This article assists the analyst in making decisions on backside thinning and polishing requirements. Thinning of the substrates can be accomplished by flat lapping, laser assisted chemical etch, plasma reactive ion etch, and CNC based milling and polishing. The article discusses the general characteristics, key principles, advantages, and disadvantages of these processes. It also contains case studies that illustrate the application of these processes to ceramic cavity devices, injection molded parts, and ball grid arrays.

This chapter discusses the failure of an aircraft control cable and the investigation that followed. It explains how visual examination showed that the failure occurred in a heavily worn section that runs over a pulley. Further examination under a stereoscope and in a SEM found that 40 out of 49 wires had thinned and broke apart, and that the remaining nine wires failed in tension evidenced by cup and cone fracture and the presence of dimples on the fracture surface. Based on their findings, investigators concluded that cable snapped because of excessive thinning due to contact wear.

A helicopter lost the outboard rib on a tail rotor blade in flight and was forced to land because of the resulting vibrations. The investigation that followed is described in this chapter along with key findings. As shown in a sketch, the rib is held in place by a set of six rivets. All of the rivets on the failed blade were missing and sections of skin were torn from most of the rivet holes. One such rivet hole was examined in a SEM, revealing corrosion on one of the tear surfaces and dimples (characteristic of ductile overload failure) on the other. In addition, the inner surface of the skin nearest the rib was found to be coated with soot, the paint on the leading edge of the top skin was abraded, and the skin in that area had thinned. Based on their findings, investigators concluded that the outboard rib separated because of stress-corrosion cracking around the rivets, and erosion may have contributed.

This article provides an overview of the most common micro-analytical technique in the failure analysis laboratory: energy dispersive X-ray spectroscopy (EDS). It discusses the general characteristics, advantages, and disadvantages of some of the X-ray detectors attached to the scanning electron microscope chamber including the lithium-drifted EDS detector, silicon drift detector (SDD), and wavelength dispersive X-ray detector. The article then provides information on qualitative and quantitative X-ray analysis programs followed by a discussion on EDS elemental mapping. The discussion includes a comparison of scanning transmission electron microscope-EDS elemental mapping and mapping with an SDD. A brief section is devoted to the discussion on the artifacts that occur during X-ray mapping.

This chapter presents the theory and practice associated with the application of thin films. The first half of the chapter describes physical deposition processes in which functional coatings are deposited on component surfaces using mechanical, electromechanical, or thermodynamic techniques. Physical vapor deposition (PVD) techniques include sputtering, e-beam evaporation, arc-PVD, and ion plating and are best suited for elements and compounds with moderate melting points or when a high-purity film is required. The remainder of the chapter covers chemical vapor deposition (CVD) processes, including atomic layer deposition, plasma-enhanced and plasma-assisted CVD, and various forms of vapor-phase epitaxy, which are commonly used for compound films or when deposit purity is less critical. A brief application overview is also presented.

Several specialized instruments are available for the metallographer to use as tools to gather key information on the characteristics of the microstructure being analyzed. These include microscopes that use electrons as a source of illumination instead of light and x-ray diffraction equipment. This chapter describes how these instruments can be used to gather important information about a microstructure. The instruments covered include image analyzers, transmission electron microscopes, scanning electron microscopes, electron probe microanalyzers, scanning transmission electron microscopes, x-ray diffractometers, microhardness testers, and hot microhardness testers. A list of other instruments that are usually located in a research laboratory or specialized testing laboratory is also provided.

This chapter provides perspective on the physical dimensions associated with the microstructure of steel and the instruments that reveal grain size, morphology, phase distributions, crystal defects, and chemical composition, from which properties and behaviors derive. The chapter also reviews the definitions and classifications used to identify and differentiate commercial steels, including the AISI/SAE and UNS designation systems.

Transistors are the most important active structure of any semiconductor component. Performance characteristics of such devices within the specifications are key to ensuring proper functionality and long-term reliability of the product. In this article, a summary of the semiconductor technology from design to manufacturing and the characterization methods are discussed. The focus is on two prominent MOS structures: planar MOS device and FinFET device. The article covers the device parameters and device properties that determine the design criteria and the device tuning procedures. The discussion includes the effects of drain induced barrier lowering, velocity saturation, hot carrier degradation, and short channel on these devices.

This chapter discusses the use of electron microscopy in metallographic analysis. It explains how electrons interact with metals and how these interactions can be harnessed to produce two- and three-dimensional images of metal surfaces and generate crystallographic and compositional data as well. It discusses the basic design and operating principles of scanning electron microscopes, transmission electron microscopes, and scanning transmission electron microscopes and how they are typically used. It describes the additional information contained in backscattered electrons and emitted x-rays and the methods used to access it, namely wavelength and energy dispersive spectroscopy and electron backscattering diffraction techniques. It also describes the role of focused ion beam milling in sample preparation and provides information on atom probes, atomic force microscopes, and laser scanning microscopes.

The various types of stainless steel have very different deformation characteristics in terms of strain hardening and anisotropy. It is important to understand and exploit these characteristics to optimize forming of stainless steels. This chapter discusses the various deformation processes involved in sheet-forming techniques, namely stretch forming and deep drawing. In addition, it provides information on some of the factors pertinent to cold-heading and hot forming of stainless long products.

This article presents six case studies of failures with steel forgings. The case studies covered are crankshaft underfill; tube bending; spade bit; trim tear; upset forging; and avoidance of flow through, lap, and crack. The case studies illustrate difficulties encountered in either cold forging or hot forging in terms of preforge factors and/or discontinuities generated by the forging process. Supporting topics that are discussed in the case studies include validity checks for buster and blocker design, lubrication and wear, mechanical surface phenomenon, forging process design, and forging tolerances. Wear, plastic deformation processes, and laws of friction are introduced as a group of subjects that have been considered in the case studies.

Post-mortem analysis of photovoltaic modules that have degraded performance is essential for improving the long term durability of solar energy. This article focuses on a general procedure for analyzing a failed module. The procedure includes electrical characterization followed by thermal imaging such as forward bias, reverse bias, and lock-in, and emission imaging such as electroluminescence and photoluminescence imaging.

This chapter begins with an overview of the history of ion nitriding. This is followed by sections that describe how the ion nitriding process works, glow discharge characteristics, process parameters requiring good control, and the applications of plasma processing. The chapter explores what happens in the ion nitriding process and provides information on its gas ratios. It describes the reactions that occur at the surface of the material being treated during iron nitriding and defines corner effect and nitride networking. Further, the chapter provides information on the stability of surface layers and processes involved in the degradation of surface finish and control of the compound zone formation. Gases primarily used for ion nitriding and the control parameters used in ion nitriding are also covered. The chapter also presents the philosophies and advantages of the plasma generation technique for nitriding. It concludes with processes involved in oxynitriding.

This chapter describes some of the most effective tools for investigating boiler tube failures, including scanning electron microscopy, optical emission spectroscopy, atomic absorption spectroscopy, x-ray fluorescence spectroscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. It explains how the tools work and what they reveal. It also covers the topic of image analysis and its application in the measurement of grain size, phase/volume fraction, delta ferrite and retained austenite, inclusion rating, depth of carburization/decarburization, scale thickness, pearlite banding, microhardness, and hardness profiles. The chapter concludes with a brief discussion on the effect of scaling and deposition and how to measure it.

This chapter discusses radiography methods using x-rays, gamma rays, and neutrons. It begins with a discussion on the applications and principles of radiography followed by sections providing information on the sources of radiation, classifications, and characteristics of x-ray tubes. Three primary attenuation processes of electromagnetic radiation, namely photoelectric effect, Compton scattering, and pair production, are covered. The chapter then discusses the principles of shadow formation, the process involved in the conversion of radiation into a form suitable for observation, and the characteristics of x-ray film. It provides information on various exposure factors in film radiography. The chapter provides a description of the characteristics that differentiate neutron radiography from x-ray or gamma ray radiography. The application of neutron radiography is described in terms of its advantages for improved contrast on low atomic number materials, discrimination between isotopes, or inspection of radioactive specimens.

This chapter covers a wide range of finishing and coating operations, including cleaning, honing, polishing and buffing, and lapping. It discusses the use of rust-preventative compounds, conversion coatings, and plating metals as well as weld overlay, thermal spray, and ceramic coatings and various pack cementation and deposition processes. It also discusses the selection and use of industrial paints and paint application methods.

The overall chemical composition of metals and alloys is most commonly determined by x-ray fluorescence (XRF) and optical emission spectroscopy (OES). High-temperature combustion and inert gas fusion methods are typically used to analyze dissolved gases (oxygen, nitrogen, and hydrogen) and, in some cases, carbon and sulfur in metals. This chapter discusses the operating principles of XRF, OES, combustion and inert gas fusion analysis, surface analysis, and scanning auger microprobe analysis. The details of equipment set-up used for chemical composition analysis as well as the capabilities of related techniques of these methods are also covered.

The relationship of stress and strength gradients must be considered simultaneously in analysis of a particular type of fracture. This chapter discusses the principal elastic stress distribution in members of various shapes under different types of pure loads. A basic understanding of both the stress and strength gradients of metal parts with and without stress concentrations and under different types of loading is provided. The chapter also describes the effect of service conditions on applied stresses.

This chapter describes the characteristic damage of a mid-air explosion and how it appears in metal debris recovered from crash sites of downed aircraft. It explains that explosive forces produce telltale signs such as petaling, curling, spalling, spikes, reverse slant fractures, and metal deposits. Explosive forces can also cause ductile metals such as aluminum to disintegrate into tiny pieces and are associated with chemicals that leave residues along with numerous craters on metal surfaces. The chapter provides examples of the different types of damage as revealed in the investigation of two in-flight bombings.