ASTM F1512-94(2003)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:F1512–94 (Reapproved 2003)
Standard Practice for
Ultrasonic C-Scan Bond Evaluation of Sputtering
Target-Backing Plate Assemblies
This standard is issued under the fixed designation F1512; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.9 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This practice describes a method for ultrasonic mapping
responsibility of the user of this standard to establish appro-
of the soundness of a bond joining a sputtering target to its
priate safety and health practices and determine the applica-
supporting backing plate. The results of the examination may
bility of regulatory limitations prior to use.
be used in predicting the target-backing plate assembly’s
suitability for use. Accept/reject standards are not specified;
2. Referenced Documents
thesearesubjecttoagreementbetweentargetsupplieranduser,
2.1 ASTM Standards:
depending upon the application requirements.
E127 Practice for Fabricating and Checking Aluminum
1.2 This standard is intended to be used with Practice
Alloy Ultrasonic Standard Reference Blocks
E1001.
E428 Practice for Fabrication and Control of Metal, Other
1.3 The method reveals unbonded areas 0.125 in. (3 mm) in
than Aluminum, Reference Blocks Used in Ultrasonic
diameter and larger. The technique permits, for example,
Testing
unambiguous quantitative measurement of the voided area in
E1001 Practice for Detection and Evaluation of Disconti-
solder bonds.
nuities by the Immersed Pulse-Echo Ultrasonic Method
1.3.1 This technique may also show regions in which bond
Using Longitudinal Waves
integrity is marginally degraded by imperfect adhesion, for
E1316 Terminology for Nondestructive Examinations
example, areas in which oxide inclusion has inhibited the
2.2 American Society for Nondestructive Testing Standard:
development of full bond strength. Evaluation of indications of
ASNT Recommended Practice SNT-TC-1A for Personnel
degraded bond areas may vary in rigor from purely subjective
Qualification and Certification in Nondestructive Testing
to semiquantitative. Target supplier and user must agree upon
the means used to display and grade partially bonded areas.
3. Terminology
1.4 This practice is applicable to assemblies having planar
3.1 Definitions:
bonds in which the design provides at least one flat plane
3.1.1 For definitions of terms used in this practice see
parallel to the bond that may be used as the entry/exit surface
Practice E1001 and Terminology E1316.
for ultrasonic excitation.
1.5 Only the immersion pulse-echo method is covered.
4. Summary of Practice
1.6 Evaluation by this method is intended to be nondestruc-
4.1 This practice describes a preferred means of applying
tive. For target assemblies that would be degraded by immer-
PracticeE1001toobtainatwodimensionalmapoftheflawsin
sion in demineralized water, for example, for porous target
asputteringtarget-backingplatebond.Thetarget-backingplate
materials, the test should be considered a destructive one.
assembly is immersed in demineralized water, used as a
1.7 This practice is applicable to bonding methods that use
couplant, and the target-backing plate joint is scanned ultra-
a filler material to join the target and backing plate. These
sonically.
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.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
This practice is under the jurisdiction ofASTM Committee F01 on Electronics Standards volume information, refer to the standard’s Document Summary page on
and is the direct responsibility of Subcommittee F01.17 on Sputter Metallization. the ASTM website.
Current edition approved April 15, 1994. Published June 1994. DOI: 10.1520/ Available from the American Society for Nondestructive Testing, 1711 Arlin-
F1512-94R03. gate Plaza, P.O. Box 28518, Columbus, OH 43228-0518.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1512–94 (2003)
5. Significance and Use reflectedsignalissampledataratesufficienttocharacterizethe
area-modulated ultrasonic reflectance of the bond interface.
5.1 This practice supplements Practice E1001 by indicating
These data may be plotted off-line to provide an equivalent
specific equipment choices and test arrangements appropriate
C-scan map.
for evaluating sputtering target bonds.
6.1.1.2 It is intended that the C-scan plotter be set to make
5.2 The bond between sputtering target and its supporting
a full-sized map of the bonded area. If a scaling factor other
backing plate is a critical reliability element in a sputter
than 1:1 is used the enlargement/reduction factor may be
deposition system. A bond must have high thermal conductiv-
determined from the reference block scan (see 8.2.3.1, 8.3.3,
ity to provide adequate target cooling during sputtering. The
and 9.1.1).
target-backing plate joint must also have strength enough to
6.1.2 Plotter—The plotter system must be capable of re-
withstand the shear stresses caused by differential thermal
solving the reference block calibration indications (6.7) with
expansion between target and backing plate.
contrast sufficient to permit unambiguous identification by the
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.Asampling 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 E1001 (6.2).
method for visually demonstrating bond character. Practice
6.3 Search Units—Use round, immersion type, single ele-
E1001 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,
E1001.
tuned at 5 or 10 Mhz operating frequency, with focal length (in
water)of2to4in.(50to100mm)haveprovedsatisfactoryfor
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 E1001,
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
E1001 (6.5).
in a reference block (6.7) simulating the assembly under test.
6.6 Tank—Provide tank in accordance with Practice E1001
Note that for C-scan mapping of target bonds theA-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 E127 and E428.
system may be equipped with a plotter to make C-scan maps
on-line as the search unit traces a raster pattern over the test 6.7.2 Test blocks must be 1.5 in. (38 mm) square or
article’s surface. diameter, or larger. In order to duplicate the target-backing
plateassembly,testblocksmustbemadeofthesamematerials,
6.1.1.1 Suitable plotters may use an electric discharge pen
that is, having the same acoustic properties as the article under
andconductivepaper;amechanicalorelectricallinkagecauses
thetest,ofthesamethicknesses,andjoinedinthesamemanner
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
made proportional to the reflected ultrasonic pulse from the 6.7.2.1 Itiscriticalfortestblockcredibilitythatthebonding
target/backing plate interface. Alternatively, a computer-based of target and backing plate materials be sound in areas not
data acquisition system may be used in which the gated purposefully altered to provide calibration indications (6.7.4,
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