Verification of time domain theories for the reflection of ultrasonic waves from periodically rough surfaces

2002 ◽  
Author(s):  
Yanming Guo
Keyword(s):  
Time Domain ◽  
Rough Surfaces ◽  
Ultrasonic Waves

scholarly journals Ultrasonic and Spectroscopic Techniques for the Measurement of the Elastic Properties of Nanoscale Materials

2021 ◽  
Author(s):  
Marco G. Beghi
Keyword(s):  
Production Process ◽  
Elastic Properties ◽  
Time Domain ◽  
Deformation Process ◽  
Measurement Techniques ◽  
Optical Excitation ◽  
Ultrasonic Waves ◽  
Spectroscopic Techniques ◽  
Elastic Continuum ◽  
The Time Domain

Materials at the nanoscale often have properties which differ from those they have in the bulk form. These properties significantly depend on the production process, and their measurement is not trivial. The elastic properties characterize the ability of materials to deform in a reversible way; they are of interest by themselves, and as indicators of the type of nanostructure. As for larger scale samples, the measurement of the elastic properties is more straightforward, and generally more precise, when it is performed by a deformation process which involves exclusively reversible strains. Vibrational and ultrasonic processes fulfill this requirement. Several measurement techniques have been developed, based on these processes. Some of them are suitable for an extension towards nanometric scales. Until truly supramolecular scales are reached, the elastic continuum paradigm remains appropriate for the description and the analysis of ultrasonic regimes. Some techniques are based on the oscillations of purpose-built testing structures, mechanically actuated. Other techniques are based on optical excitation and/or detection of ultrasonic waves, and operate either in the time domain or in the frequency domain. A comparative overview is given of these various techniques.

Laser Ultrasonic Inspection of Solder Bumps in Flip Chip Packages Using Virtual Package Device as Reference

2010 ◽  
Author(s):  
I. Charles Ume ◽  
Jie Gong ◽  
Razid Ahmad ◽  
Abel Valdes
Keyword(s):  
Time Domain ◽  
Flip Chip ◽  
Electronic Device ◽  
Ultrasonic Inspection ◽  
Reference Method ◽  
Ultrasonic Waves ◽  
Quality Analysis ◽  
Inspection System ◽  
Solder Bumps

Flip chip package is widely used in the electronic device manufacturing industry. The top side of a flip chip device is manufactured with solder bumps. The device is then flipped on its top so that the solder bumps can be bonded to a substrate, forming the mechanical and electrical connection between the device and substrate. As a result, the solder bumps are sandwiched between the silicon die and the substrate, making them no longer visible for usual inspection. A novel solder joint inspection system capable of evaluating the quality of the hidden solder bumps on a flip chip package has been developed using laser ultrasound techniques. The system pulses a laser onto the top surface of a chip package to generate ultrasonic waves in the package and excite structural vibrations which can then be measured using an interferometer. Since defective solder bumps cause changes in the transient vibration response of a tested sample, quality of the tested sample can be assessed by correlating its vibration responses to that of a known good device. A limitation of this implementation is the necessity of a known-good reference chip package, which typically involves expensive testing using alternate methods. In this paper, the development of a method capable of generating a virtual reference chip package is presented. This method, called Hybrid Reference Method, uses a statistical approach to find which packages in a sample set are most similar and then averages their time domain signals to generate a virtual chip package, known as the Hybrid Reference Package. The signals associated with Hybrid Reference Package are then correlated with the time domain signals obtained from the packages under inspection to obtain a quality signature. Finally, defective and non-defective chip packages are separated by estimating a beta distribution that fits the quality signature histogram of the inspected packages and then determining a cutoff threshold for an acceptable quality signature. This method was applied to two types of flip chip packages where no pre-established known-good reference package was available. The results of this quality analysis were validated by comparison with electrical test and X-ray results.

A Time Domain Algorithm on the Reconstruction of Rough Surfaces

2007 ◽  
Vol 24 (3) ◽  
pp. 702-705
Author(s):  
Ren Yu-Chao ◽  
Guo Li-Xin ◽  
Wu Zhen-Sen
Keyword(s):  
Time Domain ◽  
Rough Surfaces

scholarly journals Scattering of ultrasonic waves in the MHz range from rough surfaces and rough defects in metals

1982 ◽  
Vol 72 (S1) ◽  
pp. S85-S85
Author(s):  
G. Quentin ◽  
M. de Billy ◽  
A. Jungman ◽  
F. Cohen Tenoudji
Keyword(s):  
Rough Surfaces ◽  
Ultrasonic Waves
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