Influence of a Delamination Defect Location on the Operating Life of a Multi-Layered Composite Sample

An engineering approach to estimation of the transverse shear stresses in layered composites is developed. The technique is based on the well-known D. I. Zhuravsky equation for shear stresses in an isotropic beam upon transverse bending. In general, application of this equation to a composite beam is incorrect due to the heterogeneity of the composite structure. According to the proposed method, at the first stage of its implementation, a transition to the equivalent model of a homogeneous beam is made, for which the Zhuravsky formula is valid. The transition is carried out by changing the shape of the cross section of the beam, provided that the bending stiffness and generalized elastic modulus remain the same. The calculated shear stresses in the equivalent beam are then converted to the stress values in the original composite beam from the equilibrium condition. The main equations and definitions of the method as well as the analytical equation for estimation of the transverse shear stress in a composite beam are presented. The method is verified by comparing the analytical solution and the results of the numerical solution of the problem by finite element method (FEM). It is shown that laminate stacking sequence has a significant impact both on the character and on the value of the transverse shear stress distribution. The limits of the applicability of the developed technique attributed to the conditions of the validity of the hypothesis of straight normal are considered. It is noted that under this hypothesis the shear stresses do not depend on the layer shear modulus, which explains the absence of this parameter in the obtained equation. The classical theory of laminate composites is based on the similar assumptions, which gives ground to use this equation for an approximate estimation of the transverse shear stresses in in a layered composite package.

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Latch-Up Induced Slit Voiding in Aluminum Metal Lines

ISTFA 1999: Conference Proceedings from the 25th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa1999p0145 ◽

1999 ◽

Author(s):

Chunyu Zhang ◽

Lakshmi Vedula ◽

Shekhar Khandekar

Keyword(s):

High Temperature ◽

Line Width ◽

Fold Increase ◽

Metal Line ◽

Operating Life ◽

Mixed Signal ◽

Aluminum Metal ◽

Temperature Operating ◽

Latch Up

Abstract Latch-up induced during High Temperature Operating Life (HTOL) test of a mixed signal device fabricated with 1.0 μm CMOS, double poly, double metal process caused failures due to an open in aluminum metal line. Metal lines revealed wedge voids of about 50% of the line width. Triggering of latch up mechanism during the HTOL test resulted in a several fold increase of current flowing through the ground metal line. This increase in current resulted in the growth of the wedge voids leading to failures due to open metal lines.

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Improving Yield Using Scan and DFT Based Analysis for High Performance PowerPC© Microprocessor

ISTFA 2006: Conference Proceedings from the 32nd International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2006p0407 ◽

2006 ◽

Author(s):

Ray Talacka ◽

Nandu Tendolkar ◽

Cynthia Paquette

Keyword(s):

High Performance ◽

Yield Enhancement ◽

Test Time ◽

Balance Test ◽

Specific Test ◽

Defect Location ◽

Test Methodology ◽

Memory Arrays ◽

Scan Chain ◽

Scan Pattern

Abstract The use of memory arrays to drive yield enhancement has driven the development of many technologies. The uniformity of the arrays allows for easy testing and defect location. Unfortunately, the complexities of the logic circuitry are not represented well in the memory arrays. As technologies push to smaller geometries and the layout and timing of the logic circuitry become more problematic the ability to address yield issue is becoming critical. This paper presents the added yield enhancement capabilities of using e600 core Scan Chain and Scan Pattern testing for logic debug, ways to interpret the fail data, and test methodologies to balance test time and acquiring data. Selecting a specific test methodology and using today's advanced tools like Freescale's DFT/FA has been proven to find more yield issues, earlier, enabling quicker issue resolution.

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Topside Defect Localization Using OBIRCH Analysis

ISTFA 2005: Conference Proceedings from the 31st International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2005p0095 ◽

2005 ◽

Author(s):

Clifford Howard ◽

Anusha Weerakoon ◽

Diana M. Mitro ◽

Dawn Glaeser

Keyword(s):

Functional Analysis ◽

Defect Location ◽

Analysis Tools ◽

Defect Localization ◽

Tools And Techniques

Abstract OBIRCH analysis is a useful technique for defect localization not only for parametric failures, but also for functional analysis. However, OBIRCH results do not always identify the exact defect location. OBIRCH analysis results must be used in conjunction with other analysis tools and techniques to successfully identify defect locations.

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IR Thermography for Temperature Measurements and Fault Location on AlGaN/GaN HEMTs and MMICs

ISTFA 2015: Conference Proceedings from the 41st International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2015p0253 ◽

2015 ◽

Author(s):

Lény Baczkowski ◽

Franck Vouzelaud ◽

Dominique Carisetti ◽

Nicolas Sarazin ◽

Jean-Claude Clément ◽

...

Keyword(s):

Fault Location ◽

Hot Spot ◽

Life Time ◽

High Electron Mobility Transistors ◽

Junction Temperature ◽

High Electron ◽

Ir Thermography ◽

Operating Life ◽

Gan Hemt ◽

Electron Mobility Transistors

Abstract This paper shows a specific approach based on infrared (IR) thermography to face the challenging aspects of thermal measurement, mapping, and failure analysis on AlGaN/GaN high electron-mobility transistors (HEMTs) and MMICs. In the first part of this paper, IR thermography is used for the temperature measurement. Results are compared with 3D thermal simulations (ANSYS) to validate the thermal model of an 8x125pm AIGaN/GaN HEMT on SiC substrate. Measurements at different baseplate temperature are also performed to highlight the non-linearity of the thermal properties of materials. Then, correlations between the junction temperature and the life time are also discussed. In the second part, IR thermography is used for hot spot detection. The interest of the system for defect localization on AIGaN/GaN HEMT technology is presented through two case studies: a high temperature operating life test and a temperature humidity bias test.

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Magnetic Current Imaging Power Short Localization

ISTFA 2015: Conference Proceedings from the 41st International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2015p0222 ◽

2015 ◽

Author(s):

J. Gaudestad ◽

F. Rusli ◽

A. Orozco ◽

M.C. Pun

Keyword(s):

Thermal Imaging ◽

Flip Chip ◽

Optical Microscope ◽

Fault Isolation ◽

Magnetic Current ◽

Multiple Fault ◽

Defect Location ◽

Isolation Techniques ◽

Chip Sample

Abstract A Flip Chip sample failed short between power and ground. The reference unit had 418Ω and the failed unit with the short had 16.4Ω. Multiple fault isolation techniques were used in an attempt to find the failure with thermal imaging and Magnetic Current Imaging being the only techniques capable of localizing the defect. To physically verify the defect location, the die was detached from the substrate and a die cracked was seen using a visible optical microscope.

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Singularities at the Tip of a Crack Normal to the Interface of an Anisotropic Layered Composite.

10.21236/ada131504 ◽

1983 ◽

Author(s):

T. C. T. Ting ◽

P. H. Hoang

Keyword(s):

Layered Composite

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Double-layered fiber for lightweight flexible clothing providing shielding from low-dose natural radiation

Scientific Reports ◽

10.1038/s41598-021-83272-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Seon-Chil Kim ◽

Jun Sik Son

Keyword(s):

Low Dose ◽

Layered Composite ◽

Radiation Shielding ◽

Flight Attendants ◽

Low Dose Radiation ◽

Natural Radiation ◽

Composite Yarn ◽

Materials Used ◽

Fiber Fabric ◽

Dose Radiation

AbstractNatural and medical radiation are the most frequent sources of daily low-dose radiation exposure for the general public, but these radiation levels are generally acceptable. Among various occupations, aviation crew members and medical workers are exposed to high levels of radiation from scattered rays. This study focused on developing clothing for shielding aviation crew members from natural radiation during air travel. Materials were selected considering their radiation-shielding properties. A tungsten double-layered composite yarn and a polyethylene terephthalate (PET) fiber fabric containing BaSO4 were manufactured. The characteristics and shielding performances of the products were analyzed. Prototypes of a protective scarf (for shielding the thyroid gland) and apron (for shielding the torso) for flight attendants were produced. A lightweight fabric was produced that neither restricts the movement of the wearer nor causes them skin discomfort. The shielding performances of the tungsten composite and PET fiber fabrics containing BaSO4 were 0.018 mmPb and 0.03 mmPb, respectively, demonstrating low-dose shielding that may be useful for protecting aviation crew members from scattered rays. The characteristics of the developed fibers are comparable to those of materials used in clothing production; therefore, low-dose radiation-shielding clothing could be manufactured for use in aviation, medical, and other industries.

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