ASTM F1512-94(1999)
(Practice)Standard Practice for Ultrasonic C-Scan Bond Evaluation of Sputtering Target-Backing Plate Assemblies
Standard Practice for Ultrasonic C-Scan Bond Evaluation of Sputtering Target-Backing Plate Assemblies
SCOPE
1.1 This practice describes a method for ultrasonic mapping of the soundness of a bond joining a sputtering target to its supporting backing plate. The results of the examination may be used in predicting the target-backing plate assembly's suitability for use. Accept/reject standards are not specified; these are subject to agreement between target supplier and user, depending upon the application requirements.
1.2 This standard is intended to be used with Practice E1001.
1.3 The method reveals unbonded areas 0.125 in. (3 mm) in diameter and larger. The technique permits, for example, unambiguous quantitative measurement of the voided area in solder bonds.
1.3.1 This technique may also show regions in which bond integrity is marginally degraded by imperfect adhesion, for example, areas in which oxide inclusion has inhibited the development of full bond strength. Evaluation of indications of degraded bond areas may vary in rigor from purely subjective to semiquantitative. Target supplier and user must agree upon the means used to display and grade partially bonded areas.
1.4 This practice is applicable to assemblies having planar bonds in which the design provides at least one flat plane parallel to the bond that may be used as the entry/exit surface for ultrasonic excitation.
1.5 Only the immersion pulse-echo method is covered.
1.6 Evaluation by this method is intended to be nondestructive. For target assemblies that would be degraded by immersion in demineralized water, for example, for porous target materials, the test should be considered a destructive one.
1.7 This practice is applicable to bonding methods that use a filler material to join the target and backing plate. These include solder, epoxy, and braze bonds.
1.8 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
1.9 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Designation: F 1512 – 94 (Reapproved 1999)
Standard Practice for
Ultrasonic C-Scan Bond Evaluation of Sputtering
Target-Backing Plate Assemblies
This standard is issued under the fixed designation F 1512; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope bility of regulatory limitations prior to use.
1.1 This practice describes a method for ultrasonic mapping
2. Referenced Documents
of the soundness of a bond joining a sputtering target to its
2.1 ASTM Standards:
supporting backing plate. The results of the examination may
E 127 Practice for Fabricating and Checking Aluminum
be used in predicting the target-backing plate assembly’s
Alloy Ultrasonic Standard Reference Blocks
suitability for use. Accept/reject standards are not specified;
E 428 Practice for Fabrication and Control of Steel Refer-
these are subject to agreement between target supplier and user,
ence Blocks Used in Ultrasonic Inspection
depending upon the application requirements.
E 1001 Practice for Detection and Evaluation of Disconti-
1.2 This standard is intended to be used with Practice
nuities by the Immersed Pulse-Echo Ultrasonic Method
E 1001.
Using Longitudinal Waves
1.3 The method reveals unbonded areas 0.125 in. (3 mm) in
E 1316 Terminology for Nondestructive Examinations
diameter and larger. The technique permits, for example,
2.2 American Society for Nondestructive Testing Standard:
unambiguous quantitative measurement of the voided area in
ASNT Recommended Practice SNT-TC-1A for Personnel
solder bonds.
Qualification and Certification in Nondestructive Testing
1.3.1 This technique may also show regions in which bond
integrity is marginally degraded by imperfect adhesion, for
3. Terminology
example, areas in which oxide inclusion has inhibited the
3.1 Definitions:
development of full bond strength. Evaluation of indications of
3.1.1 For definitions of terms used in this practice see
degraded bond areas may vary in rigor from purely subjective
Practice E 1001 and Terminology E 1316.
to semiquantitative. Target supplier and user must agree upon
the means used to display and grade partially bonded areas.
4. Summary of Practice
1.4 This practice is applicable to assemblies having planar
4.1 This practice describes a preferred means of applying
bonds in which the design provides at least one flat plane
Practice E 1001 to obtain a two dimensional map of the flaws
parallel to the bond that may be used as the entry/exit surface
in a sputtering target-backing plate bond. The target-backing
for ultrasonic excitation.
plate assembly is immersed in demineralized water, used as a
1.5 Only the immersion pulse-echo method is covered.
couplant, and the target-backing plate joint is scanned ultra-
1.6 Evaluation by this method is intended to be nondestruc-
sonically.
tive. For target assemblies that would be degraded by immer-
sion in demineralized water, for example, for porous target
5. Significance and Use
materials, the test should be considered a destructive one.
5.1 This practice supplements Practice E 1001 by indicating
1.7 This practice is applicable to bonding methods that use
specific equipment choices and test arrangements appropriate
a filler material to join the target and backing plate. These
for evaluating sputtering target bonds.
include solder, epoxy, and braze bonds.
5.2 The bond between sputtering target and its supporting
1.8 The values stated in inch-pound units are to be regarded
backing plate is a critical reliability element in a sputter
as the standard. The values given in parentheses are for
deposition system. A bond must have high thermal conductiv-
information only.
ity to provide adequate target cooling during sputtering. The
1.9 This standard does not purport to address all of the
target-backing plate joint must also have strength enough to
safety concerns, if any, associated with its use. It is the
withstand the shear stresses caused by differential thermal
responsibility of the user of this standard to establish appro-
expansion between target and backing plate.
priate safety and health practices and determine the applica-
1 2
This practice is under the jurisdiction of ASTM Committee F-01 on Electronics Annual Book of ASTM Standards, Vol 03.03.
and is the direct responsibility of Subcommittee F01.17 on Sputter Metallization. Available from the American Society for Nondestructive Testing, 1711 Arlin-
Current edition approved April 15, 1994. Published June 1994. gate Plaza, P.O. Box 28518, Columbus, OH 43228-0518.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 1512
5.3 Flaws in a bond, for example, voids in the joining unaided eye under ordinary room lighting conditions.
material, degrade bond performance. An inadequate bond may
6.1.3 Data Acquisition System—The data system must be
fail in service, potentially causing catastrophic separation of
capable of displaying a C-scan mode plot of the reference
the target from the backing plate. Assurance of sound bonds is
block calibration indications (6.7) with contrast and resolution
an important concern among users of sputtering equipment.
sufficient to permit unambiguous identification by unaided eye
5.4 Ultrasonic testing is accepted as an efficient method for
under ordinary room lighting conditions. A sampling rate of at
evaluating target bonds, but differences in technique inhibit
least 50/in. (2/ mm) of search unit travel is recommended.
intercomparison of results from one laboratory to another. This Display of the ultrasonic map’s features in contrasting colors
practice is intended to promote uniformity in use so that
may be used to enhance visibility.
specifications for bond integrity may be universally applied.
6.2 Voltage Regulator—Provide if necessary, in accordance
5.5 The C-span display of ultrasonic test data is a direct
with Practice E 1001 (6.2).
method for visually demonstrating bond character. Practice
6.3 Search Units—Use round, immersion type, single ele-
E 1001 upon which this practice is modeled, however, does not
ment, straight-beam (longitudinal), focused search units. The
address C-scan display. Instructions specific to the C-scan
focal length must be sufficiently long that the beam minimum
display mode are indicated in this practice. In other respects
area may be focused at the target-backing plate interface.
this practice is a section by section commentary on Practice
Search units 0.375 to 0.500 in. (9.5 to 12.5 mm) in diameter,
E 1001.
tuned at 5 or 10 Mhz operating frequency, with focal length (in
water) of 2 to 4 in. (50 to 100 mm) have proved satisfactory for
6. Apparatus
most applications.
6.1 Electronic Equipment—Provide electronic equipment in
6.4 Alarm—Not applicable for this determination.
general conformance with the requirements of Practice E 1001,
6.4.1 Gate Synchronization—Set the electronic gate syn-
6.1. It is recommended that 5 or 10 Mhz frequency be used for
chronization to lock onto the top surface echo pulse from the
testing sputtering target bonds. The equipment and its cathode-
test article (not the primary excitation pulse) as reference. Set
ray tube (CRT) display, operating in the A-scan mode, should
the gate delay and width to capture the echo pulse from the
be capable of producing echo amplitudes of at least 60 % of
target/backing plate interface.
full scale, with the noise level no greater than 20 % of full
6.5 Manipulating Equipment, should conform to Practice
scale, using an 0.125-in. (3-mm) diameter flat-bottom test hole
E 1001 (6.5).
in a reference block (6.7) simulating the assembly under test.
6.6 Tank—Provide tank in accordance with Practice E 1001
Note that for C-scan mapping of target bonds the A-scan mode
(6.6).
is used for assisting in the setup only. A-scan data are not
6.7 Reference Blocks—Ultrasonic reference blocks, often
collected or reported.
called test blocks, are used to standardize the ultrasonic
6.1.1 C-scan Plotter/Data Acquisition System—The C-scan
equipment and to evaluate indications received from disconti-
presentation is a mapping of the reflected ultrasound pulse
nuities in the test part.
intensity (peak voltage) from the target/backing plate interface
6.7.1 It is mandatory that test blocks specifically made for
as a function of position. Modulations of the reflected inten-
sputtering target testing be provided for this procedure. Blocks
sity“ indications” are indicative of variations in the metallur-
should be designed, manufactured, and tested in conformance
gical bond between target and backing plate. The electronic
with Practices E 127 and E 428.
system may be equipped with a plotter to make C-scan maps
6.7.2 Test blocks must be 1.5 in. (38 mm) square or
on-line as the search unit traces a raster pattern over the test
diameter, or larger. In order to duplicate the target-backing
article’s surface.
plate assembly, test blocks must be made of the same materials,
6.1.1.1 Suitable plotters may use an electric discharge pen
that is, having the same acoustic properties as the article under
and conductive paper; a mechanical or electrical linkage causes
the test, of the same thicknesses, and joined in the same manner
the pen to traverse the paper in synchronism with the search
as the target assembly to be evaluated.
unit’s raster of the test article. The density of the pen trace is
6.7.2.1 It is critical for test block credibility that the bonding
made proportional to the reflected ultrasonic pulse from the
of target and backing plate materials be sound in areas not
target/backing plate interface. Alternatively, a computer-based
purposefully altered to provide calibration indications (6.7.4,
data acquisition system may be used in which the gated
6.7.5). New test blocks should be surveyed using the method of
reflected signal is sampled at a rate sufficient to characterize the
Section 8 after laminating. Imperfect bonds should be re-
area-modulated ultrasonic reflectance of the bond interface.
worked or the test blocks discarded.
These data may be plotted off-line to provide an equivalent
6.7.3 The top surface finish of the test blocks must be the
C-scan map.
same as the article under test.
6.1.1.2 It is intended that the C-scan plotter be set to make
a full-sized map of the bonded area. If a scaling factor other 6.7.4 Three precision flat bottomed holes, arranged in a
than 1:1 is used the enlargement/reduction factor may be pattern as illustrated in Fig. 1 must be drilled from the back
determined f
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