Influence of Vertical Hole Defects on Ultrasonic Test

Abstract Bond pad metal corrosion was observed during assembly process characterization of a 0.13um Cu microprocessor device. The bond pad consisted of 12kÅ of Al-0.5%Cu atop 9kÅ of Cu, separated by a thin Ta diffusion barrier. The corrosion was first noted after the wafer dicing process. Analysis of the pad surface revealed pitting-type corrosion, consistent with published reports of classic galvanic cell reactions between Al2Cu (theta phase) particles and the surrounding Al pad metal. Analysis of the bond pads on samelot wafers which had not been diced showed higher-thanexpected incidence of hillock and pit hole defects on the Al surface. Statistically designed experiments were formulated to investigate the possibility that the observed pre-saw pad metal defects act as nucleation sites for galvanic corrosion during the sawing process. Analyses of the experimental samples were conducted using optical and scanning electron microscopy, along with focused ion beam deprocessing and energy dispersive X-ray. This paper explores the relationship between the presence of these pre-existing defects and the propensity for the bond pads to corrode during the dicing process, and reviews the conditions under which pit hole defects are formed during the final stages of the Cu-metallized wafer fabrication process. Indications are that strict control of wafer fab backend processes can reduce or eliminate the incidence of such defects, resulting in elimination of bond pad corrosion in the wafer dicing process.

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Non-destructive testing - Characterization and verification of ultrasonic test equipment

10.3403/30363679 ◽

2020 ◽

Keyword(s):

Ultrasonic Test ◽

Test Equipment ◽

Non Destructive Testing ◽

Destructive Testing ◽

Non Destructive

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Detection of crack in painted flange gusset welded joint by ultrasonic test

Welding in the World ◽

10.1007/s40194-021-01160-w ◽

2021 ◽

Author(s):

Hiromi Shirahata ◽

Shigeyuki Hirayama ◽

Shuichi Ono ◽

Yuto Yamase

Keyword(s):

Welded Joint ◽

Ultrasonic Test

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Common issues in the hetero-epitaxial seeding on SiC substrates in the sublimation growth of AlN crystals

Applied Physics A ◽

10.1007/s00339-021-04770-9 ◽

2021 ◽

Vol 127 (8) ◽

Author(s):

R. Radhakrishnan Sumathi

Keyword(s):

Power Electronic ◽

Etch Pit ◽

Micro Hole ◽

Wet Chemical ◽

The Common ◽

Common Problems ◽

Hole Defects ◽

Sublimation Growth ◽

Impurity Elements ◽

Very High

AbstractAluminium nitride (AlN) is a futuristic material for efficient next-generation high-power electronic and optoelectronic applications. Sublimation growth of AlN single crystals with hetero-epitaxial approach using silicon carbide substrates is one of the two prominent approaches emerged, since the pioneering crystal growth work from 1970s. Many groups working on this hetero-epitaxial seeding have abandoned AlN growth altogether due to lot of persistently encountered problems. In this article, we focus on most of the common problems encountered in this process such as macro- and micro-hole defects, cracks, 3D-nucleation, high dislocation density, and incorporation of unintentional impurity elements due to chemical decomposition of the substrate at very high temperatures. Possible ways to successfully solve some of these issues have been discussed. Other few remaining challenges, namely low-angle grain boundaries and deep UV optical absorption, are also presented in the later part of this work. Particular attention has been devoted in this work on the coloration of the crystals with respect to chemical composition. Wet chemical etching gives etch pit density (EPD) values in the order of 105 cm-2 for yellow-coloured samples, while greenish coloration deteriorates the structural properties with EPD values of at least one order more.

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Ultrasonic Test on Recycled Concrete: Relationship among Ultrasonic Waves Velocity, Compressive Strength and Elastic Modulus

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.894.45 ◽

2014 ◽

Vol 894 ◽

pp. 45-49 ◽

Cited By ~ 1

Author(s):

Luisa Pani ◽

Lorena Francesconi

Keyword(s):

Compressive Strength ◽

Elastic Modulus ◽

Ultrasonic Wave ◽

Ultrasonic Test ◽

Ultrasonic Waves ◽

Recycled Concrete ◽

Recycled Aggregates ◽

Experimental Program ◽

Static Modulus ◽

Cylindrical Samples

In this paper an experimental program has been carried out in order to compare compressive strength fcand elastic static modulus Ecof recycled concrete with ultrasonic waves velocity Vp, to establish the possibility of employing nondestructive ultrasonic tests to qualify recycled concrete. 9 mix of concrete with different substitution percentage of recycled aggregates instead of natural ones and 27 cylindrical samples have been made. At first ultrasonic tests have been carried out on cylindrical samples, later elastic static modulus Ecand compressive strength fchave been experimentally evaluated. The dynamic elastic modulus Edhas been determined in function of ultrasonic wave velocity Vp; furthermore the correlations among Ed, Ec, fce Vphave been determined. It has been demonstrated that ultrasonic tests are suitable for evaluating different deformative and resisting concrete performances even when variations are small.

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A Model for Predicting Temperature of Electrofusion Joints for Polyethylene Pipes

Journal of Pressure Vessel Technology ◽

10.1115/1.4000202 ◽

2009 ◽

Vol 131 (6) ◽

Cited By ~ 12

Author(s):

Jianfeng Shi ◽

Jinyang Zheng ◽

Weican Guo ◽

Ping Xu ◽

Yongquan Qin ◽

...

Keyword(s):

Thermal Contact ◽

Power Input ◽

Ultrasonic Test ◽

Thermal Contact Conductance ◽

Transfer Model ◽

Contact Conductance ◽

One Dimensional ◽

Polyethylene Pipes ◽

Heating Wire ◽

Good Agreement

With the increasing application of electrofusion (EF) welding in connecting polyethylene (PE) pipes for gas distribution, more effort has been invested to ensure the safety of the pipeline systems. The objective of this paper is to investigate and understand the temperature distribution during EF welding. A one-dimensional transient heat-transfer model was proposed, taking the variation in the rate of power input, the phase transition of PE, and the thermal contact conductance between heating wire and PE into consideration. Then, experiments were designed to verify the power input and the temperature. The measured values of the power input were shown to be in good agreement with the analytical results. Based on ultrasonic test (UT), a new “Eigen-line” method was presented, which overcomes the difficulties found in the thermocouples’ temperature measurements. The results demonstrate good agreements between prediction and experiment. Finally, based on the presented model, a detailed parametric study was carried out to investigate the influences of the variation in the power input, the physical properties of PE, and the thermal contact conductance between heating wire and surrounding PE.

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