A High-Resolution Dry-Contact Acoustic Imaging of the Solder Joints for Ball Grid Array Assembly

2003 ◽  
Author(s):  
Hironori Tohmyoh ◽  
Masumi Saka
Keyword(s):  
Solder Joints ◽  
Ball Grid Array ◽  
Acoustic Imaging ◽  
Acoustic Microscopy ◽  
High Frequency Ultrasound ◽  
Wafer Level ◽  
Matching Layer ◽  
Acoustic Images ◽  
Dry Contact ◽  
Wafer Level Package

A new concept of acoustic microscopy for ball grid array assembly is reported. Commonly, the acoustic microscopy has to be performed with immersing the package in the coupling liquid. On the other hand, the present technique does not require the immersion of the package in the liquid, because the transduction of high frequency ultrasound is performed thorough a thin solid layer. A theoretical model is shown to perform the transduction of ultrasound more effective than usual immersion, and an acoustic matching layer, which realizes the signal amplification and the modulation, is shown. The acoustic imaging of the solder joints of a wafer level package is carried out by the present dry-contact and usual immersion techniques. The dry-contact acoustic images show the defective joint clearly, and the detectability of the defective joint is improved remarkably as compared with the usual immersion images.

Backside Application of Acoustic Micro Imaging (AMI) on Plastic Ball Grid Array (PBGA) and Plastic Quad Flat Pack (PQFP) Packages

2004 ◽  
Author(s):  
Luis A. Curiel ◽  
Andrew J. Komrowski ◽  
Daniel J.D. Sullivan
Keyword(s):  
Ball Grid Array ◽  
Acoustic Microscopy ◽  
Electronic Packages ◽  
Nondestructive Technique ◽  
Molding Compound ◽  
Microscopy Technique ◽  
Plastic Ball ◽  
Die Surface ◽  
Plastic Ball Grid Array ◽  
Bond Pads

Abstract Acoustic Micro Imaging (AMI) is an established nondestructive technique for evaluation of electronic packages. Non-destructive evaluation of electronic packages is often a critical first step in the Failure Analysis (FA) process of semiconductor devices [1]. The molding compound to die surface interface of the Plastic Ball Grid Array (PBGA) and Plastic Quad Flat Pack (PQFP) packages is an important interface to acquire for the FA process. Occasionally, with these packages, the standard acoustic microscopy technique fails to identify defects at the molding compound to die surface interface. The hard to identify defects are found at the edge of the die next to the bond pads or under the bonds wires. This paper will present a technique, Backside Acoustic Micro Imaging (BAMI) analysis, which can better resolve the molding compound to die surface interface at the die edge by sending the acoustic signal through the backside of the PBGA and PQFP packages.

scholarly journals Use of Ultrasound Microscopy for Ex Vivo Analysis of Acoustic Impedance in Mouse Liver with Steatohepatitis

Acoustics ◽  
2020 ◽  
Vol 3 (1) ◽  
pp. 3-10
Author(s):  
Hideki Kumagai ◽  
Kazuto Kobayashi ◽  
Sachiko Yoshida ◽  
Koji Yokoyama ◽  
Norio Hirota ◽  
...  
Keyword(s):  
Acoustic Impedance ◽  
Ex Vivo ◽  
Acoustic Microscopy ◽  
Control Group ◽  
Scanning Acoustic Microscopy ◽  
Central Frequency ◽  
Deficient Diet ◽  
Acoustic Images ◽  
Ultrasound Microscopy

Scanning acoustic microscopy reveals information on histology and acoustic impedance through tissues. The objective of the present study was to investigate whether acoustic impedance values in the liver over time reflect the progression of steatohepatitis through different grades and stages, and whether this approach can visualize histologic features of the disease. Mice were divided into two groups: a control group and a steatohepatitis group prepared by keeping the mice on a methionine and choline-deficient diet for 56 weeks. The hepatic lobe was excised for measurement of impedance and observation of microscopic structure using a commercially available scanning acoustic microscopy system with a central frequency of 320 MHz. Scanning acoustic microscopy revealed that acoustic impedance through liver tissue with steatohepatitis temporarily decreased with the degree of fat deposition and then increased in parallel with the progression of inflammation and fibrosis. However, the acoustic images obtained did not allow discrimination of detailed microstructures from those seen using light microscopy. In conclusion, estimation of acoustic impedance appears to have potential clinical applications, such as for monitoring or follow-up studies.

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