Physics Procedia 63 ( 2015 ) 2 – 10
Available online at www.sciencedirect.com
1875-3892 © 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Peer-review under responsibility of the Ultrasonic Industry Associationdoi: 10.1016/j.phpro.2015.03.002
ScienceDirect
43rd Annual Symposium of the Ultrasonic Industry Association, UIA Symposium 2014
Advanced bode plot techniques for ultrasonic transducers
D. A. DeAngelis and G. W. Schulze Mechanical Engineering, Ultrasonics Group, Kulicke & Soffa Industries, 1005 Virginia Drive, Fort Washington, PA 19034, USA
Abstract
The Bode plot, displayed as either impedance or admittance versus frequency, is the most basic test used by ultrasonic transducer designers. With simplicity and ease-of-use, Bode plots are ideal for baseline comparisons such as spacing of parasitic modes or impedance, but quite often the subtleties that manifest as poor process control are hard to interpret or are nonexistence. In-process testing of transducers is time consuming for quantifying statistical aberrations, and assessments made indirectly via the workpiece are difficult. This research investigates the use of advanced Bode plot techniques to compare ultrasonic transducers with known “good” and known “bad” process performance, with the goal of a-priori process assessment. These advanced techniques expand from the basic constant voltage versus frequency sweep to include constant current and constant velocity interrogated locally on transducer or tool; they also include up and down directional frequency sweeps to quantify hysteresis effects like jumping and dropping phenomena. The investigation focuses solely on the common PZT8 piezoelectric material used with welding transducers for semiconductor wire bonding. Several metrics are investigated such as impedance, displacement/current gain, velocity/current gain, displacement/voltage gain and velocity/voltage gain. The experimental and theoretical research methods include Bode plots, admittance loops, laser vibrometry and coupled-field finite element analysis. © 2014 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Ultrasonic Industry Association.
Keywords: Ultrasonic transducer; Wire bonding; Bode plots; Piezoelectric; PZT8; Vibrometer; Coupled-field FEA; ANSYS
1. Introduction
The Bode plot, displayed as impedance or admittance versus frequency, is the most basic test used by ultrasonic transducer designers. With simplicity and ease-of-use, Bode plots are ideal for baseline comparisons such as spacing of parasitic modes and impedance. But, quite often the subtleties that manifest as poor process control are hard to interpret or are nonexistent from standard Bode plots. In-process testing of transducers is time consuming for quantifying statistical aberrations, and assessments made indirectly via the workpiece are difficult for identifying
© 2015 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Peer-review under responsibility of the Ultrasonic Industry Association
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D.A. DeAngelis and G.W. Schulze / Physics Procedia 63 ( 2015 ) 2 – 10 3
cause and effect relationships. Transducer modal surveys require an expensive scanning laser vibrometer and interpretation is esoteric. Advanced bode plot techniques are needed for a-priori process assessment of ultrasonic transducers.
2. Specific transducer application
Kulicke & Soffa Industries is the leading manufacturer of semiconductor wire bonding equipment. This “back-end” type of equipment provides ultrasonically welded interconnect wires between the wafer level semiconductor circuitry (die) and the mounting package (frame) as shown in Fig. 1. The ultrasonic transducer delivers energy to a capillary tool for welding tiny gold or copper wires, typically on the order of .001 inches in diameter. Fig. 2 shows the primary steps of the wire bond cycle used to produce the interconnect wires, and how the ultrasonic energy from the transducer is delivered in a “scrubbing motion” to make the welded bonds. Fig. 1(d) shows the on-machine configuration. The single-piece construction “Unibody” transducer uses four diced, rectangular PZT8 piezoceramics, and is ideal for research studies (DeAngelis et al., 2006, 2009, 2010). Portability across 100’s of machines is required for the same customer device in production operations.
Fig. 1. (a) K&S “Unibody” ultrasonic transducer, (b) Ceramic capillary tool tip with fine gold wire compared to sewing needle, (c) Actual wire
bonds from multi-tier package, (d) On-machine configuration of “Unibody” transducer during device wire bonding.
Fig 2. Primary steps 1, 2 and 3 of the wire bond cycle
3. Assessment methodology
What aspects of transducer performance are important for ideal process control (Stansfield, 1991, Wilson, 1991, Sherman et al., 2007, Uchino et al., 2003)? The mechanical interfaces must behave linearly in vicinity of the operating mode, such that there is no separation or “gapping” with drive level or frequency change (DeAngelis et al., 2009, 2010); the critical interfaces are tool-to-clamp and the piezoceramic stack. The displacement gain of all surfaces must behave linearly in vicinity of the operating mode and proportional to drive level: the displacement/current gain should be linear in vicinity of resonance, and the displacement/voltage gain should be linear in vicinity of antiresonance (DeAngelis et al., 2006). The tool motions must be consistent in all directions above and below the operating mode: in-plane motions remain in-plane, and linear motions remain linear and in same direction. No local parasitic resonances should be competing with the operating mode; parasitic coupling has a 180° phase change when driven through the operating mode. The usual suspects are shim electrodes, tool clamps, screws and tools. Shim electrode resonances are hard to detect since their manifestation can vary wildly with slight
CapillaryTool
1¢ US
TransducerBody
Piezo Stack
New IConnTransducer
CapillaryDeviceDie
Transducer
On IConn Machine
EFO (Spark)
(a) (b) (c) (d)
4 D.A. DeAngelis and G.W. Schulze / Physics Procedia 63 ( 2015 ) 2 – 10
change of operating frequency. There should be no hysteresis in frequency or displacement gain with sweep direction; the phase lock loop (PLL) can approach arbitrarily from either side, and thus hysteresis can cause phase/amplitude oscillation or failure of PLL to lock at resonance. Interface gapping can change with phase of parasitic coupling above and below operating mode, causing hysteresis in gain and frequency. Internal self-heating effects from impedance are different above and below operating mode due to antiresonance and sweep start direction.
4. Research summary
Advanced Bode plot techniques were developed from the basic constant voltage versus frequency sweep; this included constant current and constant velocity interrogated locally on transducer (Uchino et al., 2003, Ural et al., 2009), with added up and down directional frequency sweeps to quantify hysteresis effects (Umeda et al., 2000). Selected transducers with known “good” and known “bad” process control were studied, and a linear coupled-field FEA model was correlated to the “good” transducer. The advanced Bode plot methodology for a-priori process assessment was established based on these comparisons.
5. Experimental methods and metrics
Fig. 3 shows the hardware setup for the advanced Bode plot technique. Fig. 4 shows the methodology for velocity interrogation. The tool is the “business end” of the transducer and should be a starting point. The tool clamp is a close second for interrogation, since it may exhibit more non-linearities than tool with free-air assessment (i.e., off work). As shown in Fig. 5, the piezoceramic stack should also be another target area, and especially for Langevin or sandwich transducers which are prone to uneven preload stress. High power piezo stacks can rely on adhesives in tension which can fail, and shims and preload bolts are dynamic components that are prone to resonate.
Fig. 3. Advanced Bode plot technique hardware setup.
Fig. 4. Methodology for velocity interrogation.
Laser Vibrometer Polytec OFV 056
USB I/O
Laser BeamTransducer
Network Analyzer HP E5100A
Amp 10:1
Attenuator
Ultrasonics Power Amp 4:1
Function Generator HP 33120A
USB/GPIB Interface Agilent 82357B
100Ω Resistor
Oscilloscope Tektronics DPO7054
PC Command Center(Visual Basic Program)
GPIB I/O
GPIB I/O
GPIB I/O
NA
OS
LV
VB
Vel-in
V-ref
I-inV-out
Four LCD Monitors
LV
NA
OS
Laser Dot
I-Probe
V-Probe
Vel
Top or Tip of Tool in X DirectionTop or Tip of Tool in -Y Direction
(Operating Mode Direction) Tip of Tool in Z Direction
Tool Clamp in -X Direction Piezo Stack in Z Direction
Laser Dot(X-Top) Laser Dot
(Y-Top)
Laser Dot(Z-Tip)
Laser Dot(X-Clamp)
Laser Dot(Z-Stack)
Shim Electrode in -Y Direction
Laser Dot(Y-Shim)
Laser Dot(X-Tip)
Laser Dot(Y-Tip)Y
Z
X
Z
Y
Z
X
Y
X
Y
X
Z
D.A. DeAngelis and G.W. Schulze / Physics Procedia 63 ( 2015 ) 2 – 10 5
Fig 5. Velocity interrogation target areas for typical transducers.
6. Finite element modeling
Fig. 6 shows the piezoelectric coupled-field finite element model from the ANSYS software with coupling via “stiffness” matrix which includes the piezoelectric properties for PZT8 material. The nodes have structural (X, Y, Z displacements) and electric (volt) degrees of freedom. The linear model was created without interface gapping (i.e., no gap elements) to correlate to the “good” transducer, and a constant damping ratio of 0.2% was used for all materials. The forced response was generated using a sine-sweep voltage input to the piezoceramic stack. Fig. 7 shows the FEA derived Bode results for clamp and top of capillary tool in the X-Clamp, X-Top and Y-Top directions as shown in Fig. 4; there is no hysteresis with the linear model, so results are independent of sweep direction. Fig. 8 shows the FEA derived gain ratio results for these same directions. The current and velocity gains are the same with a FEA linear model.
Fig. 6. Piezoelectric coupled-field finite element model in ANSYS software.
Fig. 7. FEA derived Bode results for clamp and top of capillary.
Preload Bolt
Piezo Stack Driver(Thru Bolted)
Wedge Tool(Long and
Heavy WC)
K&S Orthodyne Large Wire Wedge Bond Transducer(Langevin Style with Bolted Piezo Stack Driver)
K&S Maxum Ultra Transducer(Previous Model Transducer for Ball Bonding)
Piezo Stack
Ceramic Tool
Preload Wedge (3Pc.)
ToolClamp(Set
Screw)
ToolClamp(Split)
Screw
Shim Electrodes
Piezo Ceramics
Green: -Y Poled
Yellow: +Y Poled
Orange: Electrode
X-Top Y-Top
X-Clamp
CapillaryTool
6 D.A. DeAngelis and G.W. Schulze / Physics Procedia 63 ( 2015 ) 2 – 10
Fig. 8. FEA derived gain ratio results for clamp and top of capillary.
7. Experimental results
Figs. 9-12 show the advanced Bode technique results for the “good” transducer with the expected or “good” process response. As shown in Fig. 4, the velocity interrogation locations are X-Clamp, X-Top and Y-Top. The gain ratio results presented in Fig. 12 are for comparison to the linear FEA model, to demonstrate that a “good” process response is inherently a linear response. Figs. 13-17 show the advanced Bode technique results for the “bad” transducer with poor process response (i.e., inconsistent shears). The velocity interrogation locations are the same as the “good” transducer.
Fig. 9. Constant current Bode for “good” transducer with X-Clamp velocity.
X-Top Y-Top
X-Clamp
CapillaryTool
Constant Current Feedback SF5505-13 IConn
0.00
0.15
0.30
0.45
0.60
0.75
0.90
1.05
1.20
1.35
1.50
1.65
1.80
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Dis
pla
ce
me
nt/
Cu
rre
nt
(um
/A)
-100
-80
-60
-40
-20
0
20
40
60
80
100
Ad
mit
tan
ce
Ph
as
e (
De
g)
Constant Current Feedback SF5505-13 IConn
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
0.050
0.055
0.060
0.065
0.070
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Dis
pla
ce
me
nt/
Vo
lta
ge
(u
m/V
)
-105
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
105
Ad
mit
tan
ce
Ph
as
e (
De
g)
Tool Clamp in -X Direction
Laser Dot
- Hysteresis Gets Worse for Increasing Current (Normal Due to Heating)
- Fairly Constant Current Gain with Sweep Direction and Drive Level
- Some Degradation in Tool Clamping for Higher Current (Typical)
SlopeChange
Hysteresis
Constant Current Feedback SF5505-13 IConn
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
0.050
0.055
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Ad
mit
tan
ce
Ma
g (
S)
-100
-80
-60
-40
-20
0
20
40
60
80
100
Ad
mit
tan
ce
Ph
as
e (
De
g)
D.A. DeAngelis and G.W. Schulze / Physics Procedia 63 ( 2015 ) 2 – 10 7
Fig. 10. Constant current/velocity Bode for “good” transducer with X-Top velocity.
Fig. 11. Constant current/velocity Bode for “good” transducer with Y-Top velocity.
Fig. 12. Gain ratios with X and Y velocities for “good” transducer.
Constant Velocity Feedback SF5505-14 IConn
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Dis
plac
emen
t/Cur
rent
(um
/A)
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
Adm
ittan
ce P
hase
(Deg
)
Constant Current Feedback SF5505-14 IConn
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Dis
plac
emen
t/Cur
rent
(um
/A)
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
105
Adm
ittan
ce P
hase
(Deg
)
Feedback VibrometerVoltage Range Up Down
Red 7V 5 mm/s/V Solid DashedGreen 5V 25 mm/s/V Solid DashedBlue 8V 25 mm/s/V Solid Dashed
LegendSweep
Constant Velocity Feedback SF5505-14 IConn
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Dis
pla
cem
ent/V
olta
ge
(um
/V)
-80
-60
-40
-20
0
20
40
60
80
100
Ad
mitt
ance
Ph
ase
(Deg
)
- Fairly Constant Gain With Current/Velocity- X-Clamp/X-Top Current Gain Nearly 1:1
Constant Current Feedback SF5505-14 IConn
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
0.050
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Dis
pla
cem
ent/V
olta
ge
(um
/V)
-100
-80
-60
-40
-20
0
20
40
60
80
100
Ad
mitt
ance
Ph
ase
(Deg
)
Tool Top in -X Direction
Laser Dot
~Same Gain as Clamp
Constant Current Feedback SF5505-16 IConn
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Dis
plac
emen
t/Cur
rent
(um
/A)
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
105
Adm
ittan
ce P
hase
(Deg
)
Constant Current Feedback SF5505-16 IConn
0.000
0.025
0.050
0.075
0.100
0.125
0.150
0.175
0.200
0.225
0.250
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Dis
pla
cem
ent/V
olta
ge
(um
/V)
-100
-80
-60
-40
-20
0
20
40
60
80
100
Ad
mitt
ance
Ph
ase
Constant Velocity Feedback SF5505-16 IConn
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
5.50
6.00
6.50
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Dis
pla
cem
ent/C
urr
ent (
um
/A)
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
105
Ad
mitt
ance
Ph
ase
(Deg
)
Constant Velocity Feedback SF5505-16 IConn
0.000
0.025
0.050
0.075
0.100
0.125
0.150
0.175
0.200
0.225
0.250
0.275
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Dis
pla
cem
ent/V
olta
ge
(um
/V)
-85
-70
-55
-40
-25
-10
5
20
35
50
65
80
Ad
mitt
ance
Ph
ase
(Deg
)
Frequency (Hz)
C t t V l it F db k SF5
Feedback VibrometerVoltage Range Up Down
Red 8V 25 mm/s/V Solid DashedGreen 5V 125 mm/s/V Solid DashedBlue 8V 125 mm/s/V Solid Dashed
LegendSweep
- Very Consistent Gain With Current/Velocity- Overall Great Performance
Tool Top in -Y Direction
Laser Dot
Constant Current Feedback SF5505-14-16 IConn
10%
11%
12%
13%
14%
15%
16%
17%
18%
19%
20%
21%
22%
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Curre
nt G
ain
Ratio
X-T
op/Y
-Top
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
Adm
ittan
ce P
hase
(Deg
)
Constant Current Feedback SF5505-14-16 IConn
0%2%4%6%8%
10%12%14%16%18%20%22%24%26%28%30%32%
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Volta
ge G
ain
Rat
io X
-Top
/Y-T
op
-80-70-60-50-40-30-20-1001020304050607080
Adm
ittan
ce P
hase
(Deg
)
Constant Current Feedback SF5505-13-14 IConn
100%
105%
110%
115%
120%
125%
130%
135%
140%
145%
150%
155%
160%
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Curre
nt G
ain
Ratio
X-C
lam
p/X-
Top
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
Adm
ittan
ce P
hase
(Deg
)
Constant Current Feedback SF5505-13-14 IConn
0%
25%
50%
75%
100%
125%
150%
175%
200%
225%
250%
275%
300%
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Volta
ge G
ain
Rat
io X
-Cla
mp/
X-To
p
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
Adm
ittan
ce P
hase
(Deg
)
Constant Current Feedback SF5505-13-16 IConn
15%
16%17%
18%19%
20%
21%22%
23%
24%25%
26%27%
28%
29%30%
31%
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Cur
rent
Gai
n R
atio
X-C
lam
p/Y-
Top
-80
-70-60
-50-40
-30
-20-10
0
1020
3040
50
6070
80
Adm
ittan
ce P
hase
(Deg
)
Constant Current Feedback SF5505-13-16 IConn
0%
3%
6%
9%
12%
15%
18%
21%
24%
27%
30%
33%
36%
39%
121700 121800 121900 122000 122100 122200 122300 122400 122500 122600 122700
Frequency (Hz)
Volta
ge G
ain
Rat
io X
-Cla
mp/
Y-To
p
-90-80-70-60-50-40-30-20-100102030405060708090100
Adm
ittan
ce P
hase
(Deg
)
FEA Predicted
20%
FEA Predicted
25%
FEA Predicted
130%
X-TopY-Top
Gain Ratio
X-ClampY-Top
Gain Ratio
X-ClampX-Top
Gain Ratio
8 D.A. DeAngelis and G.W. Schulze / Physics Procedia 63 ( 2015 ) 2 – 10
Fig. 13. Standard Bode for “bad” transducer with X-Clamp velocity.
Fig. 14. Constant current Bode for “bad” transducer with X-Clamp velocity.
Fig. 15. Constant velocity Bode for “bad” transducer with X-Clamp velocity.
Velocity/Current 083006-1 Maxum
-40
-30
-20
-10
0
10
20
30
40
50
60
100 102 104 106 108 110 112 114 116 118 120 122 124 126 128 130 132 134 136 138 140
Frequency (kHz)
Un
it V
elo
city
/Am
ps
(dB
)
-400
-200
0
200
400
600
800
1000
1200
Ph
ase
(Deg
)
Mag Mag Down
Phase Phase Down
Velocity/Voltage 083006-1 Maxum
-80
-70
-60
-50
-40
-30
-20
-10
0
10
20
100 102 104 106 108 110 112 114 116 118 120 122 124 126 128 130 132 134 136 138 140Frequency (kHz)
Un
it V
elo
city
/Vo
lts (d
B)
-400
-200
0
200
400
600
800
1000
1200
Ph
ase
(Deg
)
Mag Mag Down
Phase Phase Down
Current/Voltage 083006-1 Maxum
0
5
10
15
20
25
30
35
40
45
50
55
60
100 102 104 106 108 110 112 114 116 118 120 122 124 126 128 130 132 134 136 138 140
Frequency (kHz)
Ad
mitt
ance
Mag
(mS
)
-120
-100
-80
-60
-40
-20
0
20
40
60
80
100
120
Ad
mitt
ance
Ph
ase
(Deg
)
Mag
Mag Down
Phase
Phase Down
Tool Clamp in -X Direction
Laser Dot
Normal Bode Response
Suspect-25dB Down
Current/Voltage Admittance Loop
-40
-30
-20
-10
0
10
20
30
40
-10 0 10 20 30 40 50 60
G (mS)
B (
mS
)
Constant Current Feedback 083006-4 Maxum Ultra
0.00
0.25
0.50
0.75
1.00
1.25
1.50
1.75
2.00
2.25
123600 123700 123800 123900 124000 124100 124200 124300 124400 124500 124600
Frequency (Hz)
Dis
pla
ce
me
nt/
Cu
rre
nt
(um
/A)
-80
-60
-40
-20
0
20
40
60
80
100
Ad
mit
tan
ce
Ph
as
e (
De
g)
Constant Current Feedback 083006-4 Maxum Ultra
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
123600 123700 123800 123900 124000 124100 124200 124300 124400 124500 124600
Frequency (Hz)
Dis
pla
ce
me
nt/
Vo
lta
ge
(u
m/V
)
-100
-80
-60
-40
-20
0
20
40
60
80
100
Ad
mit
tan
ce
Ph
as
e (
De
g)
Constant Current Feedback 083006-4 Maxum Ultra
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
0.050
0.055
0.060
123600 123700 123800 123900 124000 124100 124200 124300 124400 124500 124600
Frequency (Hz)
Ad
mit
tan
ce
Ma
g (
mS
)
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
Ad
mit
tan
ce
Ph
as
e (
De
g)
- Hysteresis Gets Worse for Increasing Current (Normal Due to Heating)
- Fairly Constant Current Gain with Sweep Direction and Drive Level
- Some Degradation in Tool Clamping for Higher Current (Normal)
Tool Clamp in -X Direction
Laser Dot
Constant Velocity Feedback 083006-4 Maxum Ultra
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
2.2
123600 123700 123800 123900 124000 124100 124200 124300 124400 124500 124600
Frequency (Hz)
Dis
pla
cem
ent/C
urr
ent (
um
/A)
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
Ad
mitt
ance
Ph
ase
(Deg
)
Feedback VibrometerVoltage Range Up Down
Red 12V 5 mm/s/V Solid DashedGreen 8V 25 mm/s/V Solid DashedBlue 14V 25 mm/s/V Solid Dashed
LegendSweep
- Fairly Consistent Gain with Sweep Direction and Velocity Level
- Little Hysteresis with Sweep Direction
- No Serious Issues at Interface from Parasitic Modes
Tool Clamp in -X Direction
Laser Dot
Constant Velocity Feedback 083006-4 Maxum Ultra
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
123600 123700 123800 123900 124000 124100 124200 124300 124400 124500 124600
Frequency (Hz)
Dis
pla
ce
me
nt/
Vo
lta
ge
(u
m/V
)
-100
-80
-60
-40
-20
0
20
40
60
80
100
Ad
mit
tan
ce
Ph
as
e (
De
g)
Constant Velocity Feedback 083006-4 Maxum Ultra
0.000
0.005
0.010
0.015
0.020
0.025
0.030
0.035
0.040
0.045
0.050
0.055
0.060
123600 123700 123800 123900 124000 124100 124200 124300 124400 124500 124600
Frequency (Hz)
Ad
mit
tan
ce
Ma
g (
S)
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
Ad
mit
tan
ce
Ph
as
e (
De
g)
D.A. DeAngelis and G.W. Schulze / Physics Procedia 63 ( 2015 ) 2 – 10 9
Fig. 16. Constant current/velocity Bode for “bad” transducer with X-Top velocity.
Fig. 17. Constant current/velocity Bodes for “bad” transducer with Y-Top velocity.
8. Conclusions
The transducer with “good” process performance conforms to behavior as predicted by the ideal linear FEA model with glued interfaces (i.e., no gap elements). Non-linear behavior in the tool was shown to be the root cause of poor process (i.e., low shear force): manufacturing error exacerbated inherent design problem in the tool clamp. Phase changes from closely spaced parasitic modes can lead to hysteresis effects due to interface gapping as seen from the non-sinusoidal velocity profile; heating effects can also cause hysteresis. Velocity based Bode plots can pick-up subtleties typically overlooked without a full laser vibrometer modal survey. A unique set of interrogation locations and assessment criteria is required for each specific transducer design and process application; wire bonding is inordinately sensitive to tool motions due to delicate balance of forces exerted on tiny ball and micro bond pad structure; inconsistent energy delivery to the tool is a root cause of poor process.
- Displacement Stability Issues with Current & Velocity Feedback- Velocity Feedback Unstable Above 2V Due to Oscillation (Non-Sinusoidal Velocity Waveform)- X-Clamp/X-Top Current Gain >10 (Gapping)
Constant Current Feedback 083006-2 Maxum Ultra
0.000
0.025
0.050
0.075
0.100
0.125
0.150
0.175
0.200
0.225
123600 123700 123800 123900 124000 124100 124200 124300 124400 124500 124600
Frequency (Hz)
Dis
pla
cem
ent/C
urr
ent (
um
/A)
-80
-60
-40
-20
0
20
40
60
80
100
Ad
mitt
ance
Ph
ase
(Deg
)
Constant Current Feedback 083006-2 Maxum Ultra
0.000
0.001
0.002
0.003
0.004
0.005
0.006
0.007
0.008
0.009
123600 123700 123800 123900 124000 124100 124200 124300 124400 124500 124600
Frequency (Hz)
Dis
plac
emen
t/Vol
tage
(um
/V)
-80
-60
-40
-20
0
20
40
60
80
100
Adm
ittan
ce P
hase
(Deg
)
Constant Velocity Feedback 083006-5 Maxum Ultra
0.00
0.01
0.02
0.03
0.04
0.05
0.06
0.07
0.08
0.09
0.10
123700 123800 123900 124000 124100 124200 124300 124400 124500
Frequency (Hz)
Dis
pla
cem
ent/C
urr
ent (
um
/A)
-100
-80
-60
-40
-20
0
20
40
60
80
100
Ad
mitt
ance
Ph
ase
(Deg
)
Constant Velocity Feedback 083006-5 Maxum Ultra
0.000
0.001
0.001
0.002
0.002
0.003
0.003
0.004
0.004
0.005
123700 123800 123900 124000 124100 124200 124300 124400 124500
Frequency (Hz)
Dis
plac
emen
t/Vol
tage
(um
/V)
-80
-60
-40
-20
0
20
40
60
80
100
Adm
ittan
ce P
hase
(Deg
)
q
Feedback VibrometerVoltage Range Up Down
Red .5V 5 mm/s/V Solid DashedGreen 1V 5 mm/s/V Solid DashedBlue 2V 5 mm/s/V Solid Dashed
LegendSweep
Phase Changes
Seen
Tool Top in –X Direction
Laser Dot
Constant Current Feedback 083006-2 Maxum Ultra
0.00.5
1.01.52.02.5
3.03.54.04.5
5.05.56.06.5
7.07.5
123600 123700 123800 123900 124000 124100 124200 124300 124400 124500 124600
Frequency (Hz)
Dis
pla
cem
ent/C
urr
ent (
um
/A)
-105-90
-75-60-45-30
-1501530
45607590
105120
Ad
mitt
ance
Ph
ase
(Deg
)
Constant Current Feedback 083006-2 Maxum Ultra
0.00
0.03
0.05
0.08
0.10
0.13
0.15
0.18
0.20
0.23
0.25
0.28
0.30
0.33
123600 123700 123800 123900 124000 124100 124200 124300 124400 124500 124600
Frequency (Hz)
Dis
pla
cem
ent/V
olta
ge
(um
/V)
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
105
Ad
mitt
ance
Ph
ase
(Deg
)
Constant Velocity Feedback 083006-2 Maxum Ultra
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
7.0
123600 123700 123800 123900 124000 124100 124200 124300 124400 124500 124600
Frequency (Hz)
Dis
pla
ce
me
nt/
Cu
rre
nt
(um
/A)
-105
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
105
Ad
mit
tan
ce
Ph
as
e (
De
g)
Feedback VibrometerVoltage Range Up Down
Red 8V 25 mm/s/V Solid DashedGreen 5V 125 mm/s/V Solid DashedBlue 8V 125 mm/s/V Solid Dashed
LegendSweep
Frequenc
Constant Velocity Feedback 083006-2 Maxum Ultra
0.000
0.025
0.050
0.075
0.100
0.125
0.150
0.175
0.200
0.225
0.250
0.275
0.300
0.325
123600 123700 123800 123900 124000 124100 124200 124300 124400 124500 124600
Frequency (Hz)
Dis
pla
ce
me
nt/
Vo
lta
ge
(u
m/V
)
-90
-75
-60
-45
-30
-15
0
15
30
45
60
75
90
105
Ad
mit
tan
ce
Ph
as
e (
De
g)
Tool Top -Y Direction
Laser Dot
- Inconsistent Gain With Current/Velocity (∆10%)- Overall Fair Performance- Root Cause: Found MFG Error in Tool Hole- Difficult to Detect with Incoming Inspection
10% Increase
10 D.A. DeAngelis and G.W. Schulze / Physics Procedia 63 ( 2015 ) 2 – 10
References
C. H. Sherman and J. L. Butler, Transducers and Arrays for Underwater Sound. New York, NY: Springer Science, 2007. D. A. DeAngelis and D. C. Schalcosky, “The Effect of PZT8 Piezoelectric Crystal Aging on Mechanical and Electrical Resonances in Ultrasonic
Transducers,” 2006 IEEE Ultrasonics Symposium, Session P2O-10. D. A. DeAngelis, G. W. Schulze, “Optimizing Piezoelectric Ceramic Thickness in Ultrasonic Transducers,” 2010 UIA Symposium Proceedings,
IEEE XPlore. D. A. DeAngelis, G. W. Schulze, “Optimizing Piezoelectric Crystal Preload in Ultrasonic Transducers,” 2009 UIA Symposium Proceedings,
IEEE XPlore. D. Stansfield, Underwater Electroacoustic Transducers. Los Altos, CA: Peninsula Publishing, 1991. K. Uchino and J. R. Giniewicz, Micromechatronics. New York, NY: Marcel Dekker, 2003. M. Umeda, K. Nakamura, S. Takahashi, S. Ueha, “An Analysis of Jumping and Dropping Phenomena of Piezoelectric Transducers using the
Electrical Equivalent Circuit Constants at High Vibration Amplitude Levels,” Japanese Journal of Applied Physics Vol. 39 (2000) pp. 5623-5628.
O. B. Wilson, Introduction to Theory and Design of Sonar Transducers. Los Altos, CA: Peninsula Publishing, 1991. S. O. Ural, S. Tuncdemir, Y. Zhuang, K. Uchino, “Development of a High Power Piezoelectric Characterization System and Its Application for
Resonance/Antiresonance Mode Characterization,” Japanese Journal of Applied Physics 48 (2009) 056509.
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