Defect analysis

Analysis of a defective part should ideally aim at determining the root cause of failure. Root cause analysis is based on the common causes of failure  

Part analysis can be accomplished by different approaches but should always begin with visual inspection. The methodology presented in this book begins with visual observation and proceeds in an escalating manner that is, the simpler analyses are to be conducted prior to more complex techniques. More 

Lined pipe Isostatic molding, melt extrusion, paste extrusion PTFE, PVDF, PFA, ETFE, ECTFE 

Pumps Injection molding, machining stock shapes PVDF, PFA, PTFE 

FIGURE 4.32 Average coefficient of friction comparison of all of the materials at the end of the test (28-30 min) (from Ref. 35). 

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Lecoeur-Taibi, I., Calmon, P., Lasserre, F., Mathonnet, H., "Mephistomis an ultrasonic modeling tool for defects analysis during in-service inspections", Proc. 14th hit. Conf. NDE Nucl. Pres. Ves. Ind., 1996, 605-608. 

Three Dimensional Defect Analysis Using Stereoradioscopy Based on Camera Modelling. 

Henzier M 1997 Capabilities of LEED for defect analysis Surf. Rev. Lett 4 489-500... 

Laser desorption methods (such as LD-ITMS) are indicated as cost-saving real-time techniques for the near future. In a single laser shot, the LDI technique coupled with Fourier-transform mass spectrometry (FTMS) can provide detailed chemical information on the polymeric molecular structure, and is a tool for direct determination of additives and contaminants in polymers. This offers new analytical capabilities to solve problems in research, development, engineering, production, technical support, competitor product analysis, and defect analysis. Laser desorption techniques are limited to surface analysis and do not allow quantitation, but exhibit superior analyte selectivity. 

Due to its unique ability to directly image the local structure of a thin object with atomic resolution, HRTEM is an extremely powerful tool for materials research. Metals, ceramics, and semiconductors are some examples of prominent materials of interest. HRTEM imaging used to be a high-end research tool mostly used in academia, but has now become standard for a wide variety of applications from materials science research to defect analysis in industrial semiconductor fabrication lines. 

M.H.LORETTO R.E.SMALLMAN, Defect analysis in electron microscopy (Interscience, New York, 1975). 

In situ direct observations of surface defect structures in catalysts under controlled reducing environments and methods for defect analysis... 

Figure 3.25. In situ catalysis (a) fresh VPO catalyst (b) dynamic real-time formation of atomic scale catalyst restructuring in butane after 2 min at 400 °C (c) enlarged image of (b) showing two sets of partial dislocations and (d) dynamic image of two sets of extended defects along symmetry-related (201) in (010) VPO after reduction in butane for several hours (diffraction contrast). The inset shows the defect nucleation near the surface. Careful defect analysis shows them to be formed by novel glide shear, (e) One set of the defects in high resolution (f) and (g) show diffraction contrast images of defects in 201 and 201. (After Gai et al, Science, 1995 and 1997 Acta Cryst. B 53 346.)...

Following the grinding or CMP process, the oxide thickness was measured by the conventional measurement tool using optical interference and the planarity was characterized by the profilometer. For the defect analysis, the defect inspection tool based on light scattering and AFM was used. 

Duerst, R.W. Stebbings, W.L. Lillquist, Gerald, J. Westberg, James, W. Breneman, William, E. Spicer, Colleen, K. Dittmar, Rebecca, M. Duerst, Marilyn, D. Depth profiling and defect analysis. In Practical Guide to Infrared Microspectroscopy Marcel Dekker, Inc. New York, 1995. 

Recent work (66) using variable-wavelength photoelectron measurements and a multichannel quantum defect analysis of the principal autolonlzlng Rydberg series has sorted out this puzzle, with the result that the shape resonance was established to be approximately where expected, but was not at all clearly Identifiable without the extensive analysis used In this case. 

T. Bailey et al.. Step and flash imprint lithography Template surface treatment and defect analysis, J. Vac. Sci. TechnoL, B, 18, 3572, 2000. 

The first consideration in defect analysis is whether the part has been handled after removal from service. Handling can alter the appearance or contaminate it to the point that either failure analysis could not be conducted or the root cause could not be determined. Surface analysis techniques are sensitive to handling and cannot distinguish between the changes caused by the failure and contamination. The best practice is to minimize handling the part and keep track of the history of the part. There are certain steps that frequently have to be taken such as decontamination of parts that have been in contact with corrosive, toxic, or flammable chemicals. A log should be considered to keep track of what has been done to the part, which may help explain any unforeseen consequences of part handling. 

This does not mean that all the analytical problems have been solved. Far from it. Evidence from various sources shows that the results of trace element analyses, as currently reported by typical laboratories around the world, may be subject to very large errors indeed. For example, the ratios of highest to lowest laboratory mean values for human blood plasma or serum reported by Versieck and Cornells (1980, see also Ver-sieck, 1985) are 392 (No. of lab. means = 17) for aluminium, 178 (7) for arsenic, 1321 (30) for chromium, 1352 (14) for cobalt 3.2 (36) for copper, 64 (19) for manganese, 7.6 (6) for mercury, 443 (10) for molybdenum, 138 (21) for nickel, 4.5 (19) for selenium, 3.4 (3) for tin, approx. 12.000 for vanadium, and 5.1 (36) for zinc. The authors conclude that many of the disparities between the values reported by different investigators are due to inadequate sampling and sample handling, or to defective analysis. 

While not wishing to diminish the importance of sampling and sample handling, the present author believes that discrepancies of these kinds are in many cases due to defective analysis. Evidence supporting this assertion can be found in the results of many intercomparisons organized by the IAEA in recent years (Parr, 1984, 1985) using some of the reference materials described later in this report. 

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