ASM Metals HandBook Vol. 17 - Nondestructive Evaluation and Quality Control
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Fig. 41 Edge effect in (a) C-SAM and (b) SLAM. In the case of C-
SAM, when the transducer is too close to the
left edge of a sample having thickness t
, the acoustic beam becomes cut off, and the echo signal does not
return from the bottom surface (side view, upper figure). Assuming a ray angle of 45°, the edge of the sample
cannot be inspected to within a distance t, thus limiting the area of scan
of a sample (top view, lower figure). If
the sample has a lateral dimension D 2t, the focused reflection mode cannot be employed i
n a valid manner.
By way of comparison, in the case of SLAM, because collimated energy is used, the edge effect is minor and
limited only by diffraction of the illumination wave at the edges (also shown in side view, upper figure, and top
view, lower figure).
Figure 42 shows a 30-MHz SLAM image of a ceramic capacitor that has a relatively uniform appearance in transmission.
The dark circular spot is a delamination that was confirmed by destructive cross sectioning of the component, as shown in
Fig. 43.
Fig. 42 SLAM image at 30 MHz of a plastic-
encapsulated ceramic capacitor having a significant defect that can
cause long-
term reliability problems. This defect is not evident by electrical testing. Field of view: 14 × 10.5
mm
Fig. 43 Cross-sectional analysis of the capacitor shown in Fig. 42
revealing a delamination in the location
indicated by SLAM. The cut edge of the capacitor was polished and placed under a conventional microscope.
The analysis of ceramic capacitors by SLAM has become a standard method for the nondestructive evaluation and
screening of ceramic capacitors for internal defects (Ref 27). Investigations have been performed to correlate the
information obtained nondestructively with that obtained by conventional destructive physical analysis. Quantitative data
have been acquired and associated with the physical properties of the materials. Users of the technique have reported
significant improvements in reliability as a result of the SLAM screening of parts.
Silicon Thyristors. The silicon thyristor, which is basically three close coupled p-n junctions in the form of a p-n-p-n
structure, is an important switching device. The thyristor has two stable states: the on state with high current and low
voltage and the off state with low current and high voltage. Because of its two stable states and the low power dissipation
in these two states, the thyristor has unique applications ranging from speed control in home appliances to switching and
power inversion in high-voltage transmission lines. The following example illustrates the use of acoustic microscopy to
evaluate whether or not a thyristor has been correctly assembled and will operate according to design specifications.
Example 4: Use of Acoustic Microscopy to Evaluate Gate-Turnoff Silicon-Controlled
Thyristor Integrity.
The performance of 77 mm (3.0 in.) diam, 5-kV, 2-kA silicon power thyristors is dependent on good electrical attachment
between the gate array and the underlying silicon device. Gate-turnoff (GTO) thyristors are fabricated by the solid-state
attachment of a conducting pattern between one large [100] cut silicon wafer and two smaller concentric annular wafer
segments also having [100] cut orientations. Both the underlying wafer and the annular segments are 0.51 mm (0.020 in.)
thick. The large underlying wafer is 77 mm (3.0 in.) in diameter, and the larger-diameter annulus is approximately 51 mm
(2.0 in.) in diameter. The successful fabrication of this silicon-controlled power device requires that the conducting
patterns be of good quality, that the wafers be intact (no cracks), and that the bonds be well attached.
Acoustic microscopy was chosen to inspect the conducting patterns at the interface between the overlying annuli and the
underlying silicon wafer. The surfaces presented to the interrogating ultrasonic beam were lapped and coated with
approximately 1.0 m (40 in.) of gold for good electrical contact.
The images shown in Fig. 44 were made by focusing a 50-MHz beam on the interface between the annuli and the
underlying wafer. This produced a resolution spot size of approximately 100 m (0.004 in.). The beam was then scanned,
and a 1024 × 1024 pixel image was acquired by recording and displaying the echo from the described interface.
Fig. 44
Thyristor gate arrays imaged through 0.51 mm (0.020 in.) of overlying [100] cut silicon. The annular
rings combined with the underlying silicon wafer make up a 5-kV, 2-kA gate-
turnoff power device. (a) This
device shows well-attached and well-
formed finger arrays. (b) This device shows poorly formed and poorly
attached arrays. The cracked spacer ring is not critical to the operation o
f (a) but was included to display cracks
as they would appear if the array annuli had cracked. Courtesy of R.S. Gilmore, General Electric Research and
Development Center
Figure 44 shows two silicon-controlled GTO thyristors that contain most of the desirable and undesirable features that can
be produced in the fabrication of a silicon power device. The device in Fig. 44(a) shows well-developed finger arrays
except for the two outer fingers at the approximate three o'clock position in the inner ring. A silicon spacer ring used to
keep the two annuli centered was badly cracked, but this ring will be removed in a subsequent fabrication operation. The
spacer ring is included in this image to show how cracks would appear in the silicon. The device in Fig. 44(b) shows very
poorly formed finger arrays, and the resulting device would probably be inoperable if it were assembled and tested. This
nondestructive evaluation of GTO thyristors demonstrated that acoustic microscopy is a valuable tool for the process and
quality control of silicon power devices.
References cited in this section
11.
F.J. Cichanski, Method and System for Dual Phase Scanning Acoustic Microscopy, Patent Pending
16.
M. Oishi, K. Noguchi, T. Masaki, and M. Mizushina, Defect Characterization of Tetragonal Zirconia
Polycrystals by a Scanning Laser Acoustic Microscope, in Proceedings of the Inte
rnational Meeting on
Advanced Materials (Tokyo), Materials Research Society MRS, 1988
17.
L.W. Kessler, J.E. Semmens, and F. Agramonte, Nondestructive Die Attach Bond Evaluation Comparing
Scanning Laser Acoustic Microscopy (SLAM) and X-Radiography, in Pro
ceedings of the 35th Electronic
Components Conference (Washington, D.C.), Institute of Electrical and Electronics Engineers, 1985, p 250-
258
18.
MIL-STD-883C, Method 2030, U.S. Government Printing Office
19.
A.R. Selfridge, Approximate Material Properties in Isotropic Materials, Trans. IEEE, Vol SU-
32 (No.
3),1985, p 381-394
20.
J.E. Semmens and L.W. Kessler, Nondestructive Evaluation of Thermally Shocked Plastic Integrated
Circuit Packages Using Acoustic Microscopy, in Proceedings of the International S
ymposium on Testing
and Failure Analysis, ASM INTERNATIONAL, 1988, p 211-215
21.
S. Lees, Ultrasonic Measurement of Thin Layers, Trans. IEEE, Vol SU-18 (No. 2), 1971, p 81-86
22.
Packaging, Vol 1, Electronic Materials Handbook, ASM INTERNATIONAL, 1989
23.
J.E. Semmens and L.W. Kessler, Nondestructive Evaluation of TAB Bonds by Acoustic Microscopy, in
Proceedings of the ISHM Conference
(Seattle, WA), International Society for Hybrid Microelectronics,
1988, p 455-463
24.
"Nondestructive Evaluation of Metallurgical Tape Bonds," Report 88-
7114, Rome Air Development Center,
Griffiss Air Force Base (summary available from Sonoscan, Inc.), 1988
25.
L.W. Kessler, Acoustic Microscopy: Nondestructive Tool for Bond Evaluation on TAB Interconnections, in
Proceedings of the ISHM Symposium
(Dallas, TX), International Society for Hybrid Microelectronics, 1984,
p 79-84
26.
G.R. Love, Nondestructive Testing of Monolithic Ceramic Capacitors, in
Proceedings of the 1973
International Microelectronics Symposium, 1A3-1A8, In
ternational Society for Hybrid Microelectronics,
1973
27.
L.W. Kessler and J.E. Semmens, Nondestructive SLAM Analysis of Ceramic Capacitors: An Overview of
Experiences From 1980-1989, in Proceedings of the Capacitor and Resistor Technology Symposium
(Orlando, FL), Components Technology Institute
Note cited in this section
* Examples 1and 3 were prepared by G.H. Thomas, Sandia National Laboratories, Livermore, CA. Example 4
was prepared by R.S. Gilmore, General Electric Research & Development Center.
Acoustic Microscopy
Lawrence W. Kessler, Sonoscan, Inc.
References
1. A. Korpel, L.W. Kessler, and P.R. Palermo, Acoustic Microscope Operating at 100 MHz, Nature,
Vol 232
(No. 5306), 1970, p 110-111
2. Product Bulletin, Sonoscan, Inc.
3. R.A. Lemons and C.F. Quate, Acoustic Microscope--Scanning Version, Appl. Phys. Lett.,
Vol 24 (No. 4),
1974, p 163-165
4. L.W. Kessler and D.E. Yuhas, Acoustic Microscopy--1979, Proc. of IEEE,
Vol 67 (No. 4), April 1979, p
526-536
5.
Z.C. Lin, H. Lee, G. Wade, M.G. Oravecz, and L.W. Kessler, Holographic Image Reconstruction in
Scanning Laser Acoustic Microscopy, Trans. IEEE, Vol UFFC-34 (No. 3), May 1987, p 293-300
6.
B.Y. Yu, M.G. Oravecz, and L.W. Kessler, "Multimedia Holographic Image Reconstruction in a Scanning
Laser Acoustic Microscope," Paper presented at the 16th International Symposium on Acoustical Imaging
(Chicago, IL), Sonoscan, Inc., June 1987; L.W. Kessler, Ed., Acoustical Imaging,
Vol 16, Plenum Press,
1988, p 535-542
7. L.W. Kessler, VHF Ultrasonic Attenuation in Mammalian Tissue, Acoust. Soc. Am.,
Vol 53 (No. 6), 1973,
p 1759-1760
8. M.G. Oravecz, Quantitative Scanning Laser Acoustic Microscopy: Attenuation, J. Phys. (Orsay),
Vol 46,
Conf. C10, Supplement 12, Dec 1985, p 751-754
9.
S.A. Goss and W.D. O'Brien, Jr., Direct Ultrasonic Velocity Measurements of Mammalian Collagen
Threads, Acoust. Soc. Am., Vol 65 (No. 2), 1979, p 507-511
10.
M.G. Oravecz and S. Lees, Acoustic Spectral Interferometry: A New Method for Sonic Velocity
Determination, in Acoustical Imaging,
Vol 13, M. Kaveh, R.K. Mueller, and T.F. Greenleaf, Ed., Plenum
Press, 1984, p 397-408
11. F.J. Cichanski, Method and System for Dual Phase Scanning Acoustic Microscopy, Patent Pending
12. J.S. Foster and D. Rugar, Low-Temperature Acoustic Microscopy, Trans. IEEE, Vol SU-32, 1985, p 139-
151
13. K.K. Liang, G.S. Kino, and B.T. Khuri-Yakub, Material Characterization by the Inversion of V(z),
Trans.
IEEE, Vol SU-32, 1985, p 213-224
14. R.D. Weglein, Acoustic Micro-Metrology, Trans. IEEE, Vol SU-32, 1985, p 225-234
15. J. Kushibiki and N. Chubachi, Material Characterization by Line-Focus-Beam
Acoustic Microscope,
Trans. IEEE, Vol SU-32, 1985, p 189-212
16.
M. Oishi, K. Noguchi, T. Masaki, and M. Mizushina, Defect Characterization of Tetragonal Zirconia
Polycrystals by a Scanning Laser Acoustic Microscope, in Proceedings of the International M
eeting on
Advanced Materials (Tokyo), Materials Research Society MRS, 1988
17.
L.W. Kessler, J.E. Semmens, and F. Agramonte, Nondestructive Die Attach Bond Evaluation Comparing
Scanning Laser Acoustic Microscopy (SLAM) and X-Radiography, in Proceedings of
the 35th Electronic
Components Conference
(Washington, D.C.), Institute of Electrical and Electronics Engineers, 1985, p
250-258
18. MIL-STD-883C, Method 2030, U.S. Government Printing Office
19. A.R. Selfridge, Approximate Material Properties in Isotropic Materials, Trans. IEEE, Vol SU-
32 (No.
3),1985, p 381-394
20.
J.E. Semmens and L.W. Kessler, Nondestructive Evaluation of Thermally Shocked Plastic Integrated
Circuit Packages Using Acoustic Microscopy, in Proceedings of the International Symposium on
Testing
and Failure Analysis, ASM INTERNATIONAL, 1988, p 211-215
21. S. Lees, Ultrasonic Measurement of Thin Layers, Trans. IEEE, Vol SU-18 (No. 2), 1971, p 81-86
22. Packaging, Vol 1, Electronic Materials Handbook, ASM INTERNATIONAL, 1989
23. J.E. Sem
mens and L.W. Kessler, Nondestructive Evaluation of TAB Bonds by Acoustic Microscopy, in
Proceedings of the ISHM Conference
(Seattle, WA), International Society for Hybrid Microelectronics,
1988, p 455-463
24. "Nondestructive Evaluation of Metallurgical Tape Bonds," Report 88-
7114, Rome Air Development
Center, Griffiss Air Force Base (summary available from Sonoscan, Inc.), 1988
25.
L.W. Kessler, Acoustic Microscopy: Nondestructive Tool for Bond Evaluation on TAB Interconnections,
in Proceedings of the ISHM Symposium
(Dallas, TX), International Society for Hybrid Microelectronics,
1984, p 79-84
26. G.R. Love, Nondestructive Testing of Monolithic Ceramic Capacitors, in
Proceedings of the 1973
International Microelectronics Symposium, 1A3-1A8, International
Society for Hybrid Microelectronics,
1973
27.
L.W. Kessler and J.E. Semmens, Nondestructive SLAM Analysis of Ceramic Capacitors: An Overview of
Experiences From 1980-1989, in Proceedings of the Capacitor and Resistor Technology Symposium
(Orlando, FL), Components Technology Institute
Use of Color for NDE
Introduction
MAJOR DEVELOPMENTS in digital electronics have led to the commercial availability of a wide range of specialized
devices for image processing and enhancement. With digital image enhancement systems, data interpretation becomes
easier, difficult-to-detect features are more readily discernible, and quantitative analysis is possible. Among the numerous
image-processing operations available (see the article "Digital Image Enhancement" in this Volume), color-enhanced
images produce some of the more valuable, if not spectacular, results.
Use of Color for NDE
Color Images
This collection of color images is intended to assist the reader in recognizing the advantages and/or limitations of
pseudocolor in NDE. This collection both complements and supplements articles in this Handbook that describe in detail
the principles and applications of methods that utilize color for discontinuity characterization. Numerous comparisons are
made between figures appearing in color in this section and their black-and-white counterparts found elsewhere in this
Volume. The types of color images appearing in this article include:
Inspection method
Fig. No.
Ultrasonic inspection
2, 3, 6(c), 6(d), 10, 21, 23
Acoustic microscopy
5, 11, 12, 13, 14, 15, 16
Thermal analysis
17, 18, 19, 20, 22
Computed tomography
1, 7, 8, 9
Digital radiography
6(a), 6(b)
Stress analysis
(a)
24
(a)
The photoelastic fringe patterns shown in Fig. 24 are the result of stress/strain analysis. See the article "Strain Measurement for Stress
Analysis" for details.
Fig. 1 Computed tomographic reconstruction of a 9-
V battery. (a) Image reconstructed from 500 views
showing evidence of undersampling. (b) Image reconstructed from 1000 views, the data filtered with a Wiener
filter before backprojection to correct for the point spread of the beam.
(T.N. Claytor, Los Alamos National
Laboratory)
Fig. 2 Linear histogram equalization (image enhancement technique) of a low-
contrast ultrasonic image of a
bond line in an explosively bonded steel-to-
aluminum plate. The detonation wave travels from top to bottom,
with higher values of intensity indicating better bonding
. (a) and (b) Digitized image with 64 levels and
corresponding histogram. (c) and (d) After the histogram equalization process, the colors are more widely
separated so that the subtler features of the bonding can be seen. (T.N. Claytor, Los Alamos National
Laboratory)
Fig. 3 Effects of a low-pass filter and a median filter on a slightly noisy ultrasonic image of a cross-
rolled
t
ungsten plate with internal rolling tears. (a) The original image has point noise and horizontal streaks. (b)
After low-
pass filtering, the point noise has been eliminated, but the streaks are still visible. (c) After median
filtering, the point noise is e
liminated, the streaks are less prominent, and the sharpness of the original image
is preserved. (T.N. Claytor, Los Alamos National Laboratory)
Fig. 4 Palettes useful for black-and-
white and color presentation of data. (a) Standard linear gray scale. (b)
Gray scale with a red threshold for identifying out-of-
bound conditions. (c) The most colorful palette spectrum.
(d) and (e) Complementary palettes. (T.N. Claytor, Los Alamos National Laboratory)
Fig. 5 50-MHz acoustic microscope image of a stainless steel-to-
stainless steel diffusion bond with a silver
interlayer. The blue, white, and black areas indicate poorer bonding. The pattern displayed in this image
matched the ductile/brittle pattern on the fracture surface. (G.H. Thomas, Sandia National Laboratories)
Fig. 6
Examples of contrast enhancement techniques. (a) Radiograph and corresponding line density chart of a
ceramic disk containing inclusions (white) and voids (dark areas). (b) After a field-
flattening contrast
enhancement procedure, the large voids and inclusions are more easily detected at the expense of smaller
voids. (c) Ultrasonic image of a HIPed tungsten plate
showing density variations enhanced by the use of color.
(d) Ultrasonic image of a hot-rolled tungsten plate showing texture variations. Compare Fig. 6(c) and 6
(d) with
Fig. 6 and 7 in the article "Digital Image Enhancement." (T.N. Claytor, Los Alamos National Laboratory)
Fig. 7 Digital replica of a three-
dimensional surface image of a turbine blade generated from computed
tomography data (M.J. Dennis, General Electric NDE Systems and Services)