Failure Analysis Procedure Research Articles

Strength analysis of filament-wound composite tubes

The subject of this work is focused on strength analysis of filament-wound composite tubes made of E glass/polyester under internal pressure. The primary attention of this investigation is to develop a reliable computation procedure for stress, displacement and initial failure analysis of layered composite tubes. For that purpose we have combined the finite element method (FEM) with corresponding initial failure criterions. In addition, finite element analyses using commercial code, MSC/NASTRAN, were performed to predict the behavior of filament wound structures. Computation results are compared with experiments. Good agreement between computation and experimental results are obtained.

Laser-Based Target Preparation in 3D Integrated Electronic Packages

The trend toward 3D integration in electronic packaging requires that failure analysis procedures and target preparation methods are adapted from conventional discrete packages to these emerging packaging technologies. This paper addresses the feasibility of laser-based target preparation in 3D integrated devices, especially stacked-die packages. Various laser technologies such as ultrashort-pulse lasers, excimer lasers, and diode-pumped solid-state (DPSS) lasers with different wavelengths and pulse durations were evaluated. In particular, it was found that ultrashort-pulse lasers with pulse durations in the femtosecond range were not suitable for ablation of the molding compound (MC). Picosecond lasers were applicable with certain constraints. It was found that for MCs with high filler content, DPSS lasers with pulse durations in the nanosecond range were the best choice. For the removal of stacked silicon dies, the laser wavelength was the most important factor in artifact-free thinning. Laser cross sections through several silicon dies with remarkably small heat-affected zones were also demonstrated. The distinct removal of the MC, silicon dies, and metal interconnected with a single laser source offers new opportunities for laser-based target preparation in 3D integrated electronic packaging devices.

IGBT module failure analysis in railway applications

This work reports two different characteristic patterns detected in IGBT chips failed in real operation (railway application) by failure analysis procedures. The analysed chips have been recovered from the rheostatic chopper leg and from the three legs which supplies the traction motor. It is observed that depending on the location and characteristics of the detected default (burn-out spot), this failure can be attributed to a latch-up process or a secondary breakdown mechanism. These results are corroborated with tests at limit, obtaining the same result. Consequently, each failure can be linked to overcurrent (latch-up) or overtemperature (secondary breakdown) events, which makes possible to distinguish between problems coming from driving strategies or thermal issues (uneven temperature distribution inside the module or packaging wear-out).

Premature fracture in automobile leaf springs

In this work, the origin of premature fracture in leaf springs, used in Venezuelan buses, is studied. To this end, common failure analysis procedures, including examining the leaf spring history, visual inspection of fractured specimens, characterization of various properties and simulation tests on real components, were used. It is concluded that fracture occurred by a mechanism of mechanical fatigue, initiated at the region of the central hole, which suffered the highest tensile stress levels. Several factors (poor design, low quality material and defected fabrication) have combined to facilitate failure. Preventive measures to lengthen the service life of leaf springs are suggested.

Fretting fatigue in overhead conductors: Rig design and failure analysis of a Grosbeak aluminium cable steel reinforced conductor

The performance optimisation of overhead conductors depends on the systematic investigation of the fretting fatigue mechanisms in the conductor/clamping system. As a consequence, a fretting fatigue rig was designed and a limited range of fatigue tests was carried out at the middle high cycle fatigue regime in order to access an exploratory S – N curve for a Grosbeak conductor, which was mounted on a mono-articulated aluminium clamping system. Subsequent to these preliminary fatigue tests, the components of the conductor/clamping system, such as ACSR conductor, upper and lower clamps, bolt and nuts, were subjected to a failure analysis procedure in order to investigate the metallurgical free variables interfering on the fatigue test results, aiming at the optimisation of the testing reproducibility. The results indicated that the rupture of the planar fracture surfaces observed in the external Al strands of the conductor tested under lower bending amplitude (0.9 mm) occurred by fatigue cracking (1 mm deep), followed by shear overload. The V-type fracture surfaces observed in some Al strands of the conductor tested under higher bending amplitude (1.3 mm) were also produced by fatigue cracking (approximately 400 μm deep), followed by shear overload. Shear overload fracture (45° fracture surface) was also observed on the remaining Al wires of the conductor tested under higher bending amplitude (1.3 mm). Additionally, the upper and lower Al-cast clamps presented microstructure-sensitive cracking, which was folowed by particle detachment and formation of abrasive debris on the clamp/conductor tribo-interface, promoting even further the fretting mechanism. The detrimental formation of abrasive debris might be inhibited by the selection of a more suitable class of as-cast Al alloy for the production of clamps. Finally, the bolt/nut system showed intense degradation of the carbon steel nut (fabricated in ferritic–pearlitic carbon steel, featuring machined threads with 190 HV), with intense plastic deformation and loss of material. Proper selection of both the bolt and nut materials and the finishing processing might prevent the loss in the clamping pressure during the fretting testing. It is important to control the specification of these components (clamps, bolt and nuts) prior to the start of large scale fretting fatigue testing of the overhead conductors in order to increase the reproducibility of this assessment.

Analysis of solder joint failures arisen during the soldering process

The paper gives an overview of the analysis methods applied by electronic failure analysis laboratories for detection, localization and in depth analysis of solder joint failures. The paper focuses on failures that arise during the soldering process. Besides the analysis methods case studies and a few failure modes together with their inspection and root causes are also described. Optical microscopy is used for sample documentation and failure localization. X-ray microimaging can be applied to non-destructively inspect hidden joints i.e. BGA (ball grid array), flip-chip, CSP (chip scale package) bump and micro-wire. It can be also used to measure the amount of solder or voids in the joints. Inspection of PWB (printed wiring board) tracks and via metallization can also be carried out by these systems. SAM (scanning acoustic microscopy) is an effective tool to detect and to visualize delaminations or cracks inside electronics packages or assemblies. As failures are in most cases retraceable to material or compo sitional problems, SEM (scanning electron microscopy) together with electron microprobe analysis can be applied to find the root cause of failures. Thorough analysis of a broken solder joint, wetting problem of cut surfaces, delamination and insufficient through-hole solder joints are presented in the paper. By these case studies not only the failure analysis procedure can be demonstrated, but also the root causes of these failures are revealed.

Air conditioner failure investigation-intergranular cracking in a pure copper condenser tube

A failure of a 7 1/2-year-old commercial rooftop air conditioning system was investigated. The systematic failure analysis procedure and eventual discovery of a leak in a pure copper condenser coil are discussed. Severe denting of several tubes, including the tube that leaked, was discovered in the area of the steel tube sheet. A metallurgical examination, including scanning electron microscopy, revealed intergranular cracking, a process that is common among some copper alloys suffering from stress-corrosion cracking but is rarely observed in pure copper. Research of available literature is presented, and the conditions under which pure copper may exhibit intergranular cracking are discussed. Also presented are vibration measurements of the air conditioner taken during operation, which rule out operating loads as the cause of the tube denting and eventual cracking. The cause of the denting remains unknown. However, the denting probably occurred during manufacturing, and the high stresses associated with the dents, in the presence of corrosion, resulted in intergranular cracking and eventual leaking.

Smoothed Particle Hydrodynamics法による粒状地盤の浸透破壊解析手法の開発

Smoothed Particle Hydrodynamics法による粒状地盤の浸透破壊解析手法の開発

Water chemistry and processing effects on the corrosion degradation of copper tubing in cooling water systems

Specimens of copper tubing from an industrial scale chiller were subjected to a complete corrosion failure analysis. Nondestructive inspection of the tubing indicated substantial corrosion damage and provided the impetus for the corrosion analysis. By application of the typical methods encountered in metallurgical failure investigations, as well as additional chemical analysis techniques, the most probable cause of failure was identified to be a change in the water chemistry during the service life of the tubes. Additional items that may have contributed to the failure include the geometric design of the tube and the post-manufacture cleaning process prior to service. Recommendations were made regarding water treatment and the requirements for any replacement tubes. In addition to discussion of the specific failure(s) investigated, notes regarding the general procedures for corrosion failure analysis are also presented.

Failure of Nickel-Aluminum-Bronze Hydraulic Couplings, with Comments on General Procedures for Failure Analysis

Failure of Nickel-Aluminum-Bronze Hydraulic Couplings, with Comments on General Procedures for Failure Analysis

Failure of nickel-aluminum-bronze hydraulic couplings, with comments on general procedures for failure analysis

Failures of various types of hydraulic couplings used to connect pipes in a naval vessel are described and used to illustrate some of the general procedures for failure analysis. Cracking of couplings, which were manufactured from nickel-aluminum-bronze extruded bar, occurred in both seawater and air environments. Cracks initiated at an unusually wide variety of sites and propagated in either longitudinal or circumferential directions with respect to the axis of the couplings. Fracture surfaces were intergranular and exhibited little or no sign of corrosion (for couplings cracked in air), and there was very limited plasticity. Macroscopic progression markings were observed on fracture surfaces of several couplings but were not generally evident. At very high magnifications, numerous slip lines, progression markings, and striations were observed. In a few cases, where complete separation had occurred in service, small areas of dimpled overload fracture were observed. It was concluded from these observations, and from comparisons of cracks produced in service with cracks produced by laboratory testing under various conditions, that cracking had occurred by fatigue. The primary cause of failure was probably the unanticipated presence of high-frequency stress cycles with very low amplitudes, possibly due to vibration, resonance, or acoustic waves transmitted through the hydraulic fluid. Secondary causes of failure included the presence of high tensile residual stresses in one type of coupling, undue stress concentrations at some of the crack-initiation sites, and overtorquing of some couplings during installation. Recommendations on ways to prevent further failures based on these causes are discussed.

STAGS computational procedure for progressive failure analysis of laminated composite structures

Non-linear analyses are difficult simulations to perform and place increased demands not only on the computational systems but also on the analyst. The number of possible problems and/or difficulties increases significantly compared to those for linear elastic analyses. Combined material and geometric non-linearities challenge the analyst and the solution algorithms. Progressive failure and damage propagation for composite structures result in even more complexities due to the discrete, abrupt changes in local material stiffness. Analysts need to interrogate the computed solutions carefully based on their understanding of structural mechanics, material behavior, computational procedures and non-linear phenomena to distill correct physics from such simulations. This paper describes the computational strategy incorporated into the STAGS non-linear finite element analysis code with special emphasis on progressive failure analysis of laminated composite structures. Results for selected laminated composite structures are used to demonstrate the PFA capability.

Specific preparation procedures for failure analysis of (sub)micron areas in silicon devices

Special preparation techniques have to be applied for trans-mission electron microscope (TEM) failure analysis of ULSI devices as well as for technology characterization of non-periodic test patterns to obtain information from volumes as small as 1 × 1× 1 μm 3. These regions may be prepared either as thin cross sections or as planview specimens by making use of a well established precision polishing technique. In this article strategical preparation steps are described which have to be thought of and carried out depending on the specific problem before the specimen is actually thinned. This comprises the choice of localization and marking techniques for the area of interest and the consideration whether layers which cover the surface of the Si substrate and impede TEM observation should be removed by either chemical or mechanical means. Precise ion milling of planview specimens becomes necessary to remove thin residual polycrystalline layers on the Si substrate which disturb TEM observation of defects in the silicon near-surface zone due to diffraction contrast. Particular problems require specimens a few micrometers thick, to be studied in an 1 MV TEM first in order to locate the exact position of the interesting features. Further ion milling may then provide a thin specimen usable for characterization by imaging and composition analysis. The varoius approaches and procedures will be illustrated by numerous examples taken from memory and logic device technology.

Use of Linear Elastic Fracture Mechanics in the In-service Fracture Analysis of Structural Components

AbstractThe proposed failure analysis procedure requires six important steps which are a combination of the fractographic analysis and the application of approximation method based on linear elastic fracture mechanics. This procedure was applied to an in-service failure of an anchor bar of a high-voltage transmission line tower.Microscopic observations of the fracture surface indicated multiple crack initiation sites and brittle intergranular features mixed with transgranular cleavage fracture. This is probably caused by the hydrogen embrittlement which produced a weakening of the material properties at the toe of the fillet which could be assumed to produce a narrow axisymmetric crack at the fillet toe. The remote stress needed to produce failure was analysed for different crack sizes and different applied stress intensity factor, K I. The fracture toughness K IC was insufficient for this material. Higher fracture toughness would have been required or the problem would need to have been detected by quali...

New application of laser beam to failure analysis of LSI with multi-metal layers

A new technique for failure analysis of LSI with multi metal layers is described. There is a fabrication technique to form a big and optional window on upper layers using Nd-YAG laser without destroying any electrical function, and to approach the failure point through this window. The failure analysis procedure based on logical flow is presented. Fabrication technique is located in part of this procedure which consists of four steps. Two difficult reasons for approaching the failure point without fabrication technique are described. This difficulty results from line composition and line width. The fabrication procedure using Nd-YAG laser is reported. This procedure is to cover the chip surface with photo resist, and form a big and optional size window on upper layer with laser beam, and finally expose the purposed layer. Three failure analysis examples using this technique are introduced: unformed contact falure mode, Si-noduled failure mode, and isolation destroying failure mode.

Common cause failure analysis: A critique and some suggestions

Abstract This paper presents a critical review of a recently proposed procedure for a quantitative common cause failure analysis. Limitations resulting from the quality of the data base and the lack of guidance for event interpretation are highlighted. It is suggested that more effort needs to be made to understand and provide for a more consistent and detailed description of failure mechanisms. A review process, based on the assessment of the adequacy of the defensive strategy in place at a plant, is proposed as a supplement to the current approach based on a review of historical events to identify, in a more complete fashion, potential CCF mechanisms.

Comments on ‘basic aspects of stochastic reliability analysis for redundancy systems’

This paper presents a critical review of a recently proposed procedure for a quantitative common cause failure analysis. Limitations resulting from the quality of the data base and the lack of guidance for event interpretation are highlighted. It is suggested that more effort needs to be made to understand and provide for a more consistent and detailed description of failure mechanisms. A review process, based on the assessment of the adequacy of the defensive strategy in place at a plant, is proposed as a supplement to the current approach based on a review of historical events to identify, in a more complete fashion, potential CCF mechanisms.

A structured procedure for dependent failure analysis (DFA)

A recent European Benchmark Exercise has once again provided some evidence that dependent failures can dominate a reliability assessment by three or four orders of magnitude. In any reliability analysis the effect of dependent failures must therefore be assessed. Methods and procedures currently exist which make a dependent failure assessment possible. The best general approach available now, it is contended, is a systems approach which takes account of system defences in evaluating the contribution of dependent failures. A structured procedure for such an approach is presented.

Failure analysis in semiconductor devices – rationale, methodology and practice

In order to carry out effective failure analysis on semiconductor devices, it is essential to have a disciplined analytical schedule to ensure that no relevant information is lost by virtue of any haphazard approach. This paper describes the rationale, approach and procedure for failure analysis (including de-packaging, selective layer removal and location of defects), some procedural problems and the consequent necessity for techniques complementary to microscopy. The results of a number of failure analyses are presented from numerous investigations on devices ranging from high power thyristors to microwave devices, discrete transistors and ICs, originating from field failures, OA goods inwards inspection and in-house fabricated devices. The problems involved in identifying particular mechanisms and causes of failure, and their assignment as being design, materials, processing or applications induced are discussed. Suggestions are made concerning the need for additional techniques for failure analyses on future generation devices.

Failure analysis in semiconductor devices—rationale, methodology and practice : B. P. Richards and P. K. Footner. Microelectron. J.15 (1), 5 (1984)

In order to carry out effective failure analysis on semiconductor devices, it is essential to have a disciplined analytical schedule to ensure that no relevant information is lost by virtue of any haphazard approach. This paper describes the rationale, approach and procedure for failure analysis (including de-packaging, selective layer removal and location of defects), some procedural problems and the consequent necessity for techniques complementary to microscopy. The results of a number of failure analyses are presented from numerous investigations on devices ranging from high power thyristors to microwave devices, discrete transistors and ICs, originating from field failures, OA goods inwards inspection and in-house fabricated devices. The problems involved in identifying particular mechanisms and causes of failure, and their assignment as being design, materials, processing or applications induced are discussed. Suggestions are made concerning the need for additional techniques for failure analyses on future generation devices.