Transcript ‘L-Cell’ A Novel Device for Plating Process Diagnostics L-Chem, Inc. Shaker Heights, OH 44120 www.L-Chem.com Introducing a novel, multi-purpose device that provides: • Process parameters • Process diagnostics • Fully.

‘L-Cell’
A Novel Device for Plating
Process Diagnostics
L-Chem, Inc.
Shaker Heights, OH 44120
www.L-Chem.com
Introducing a novel, multi-purpose
device that provides:
• Process parameters
• Process diagnostics
• Fully automated
• No expertise required
• Fast (2 min./test)
OUTLINE
•
•
•
•
•
Rationalle and need
Current tecnology and its defficiencies
The L-Cell - principles and description
Examples
Conclusions
Issues in Plating
 Predictive Design
 Meeting Specs., Optimization
 Process Control and Maintenance
 Environmental and Health
 New Materials
Available Tools

Predictive Design
 Optimization
}
Computer Aided Design
Software - ‘Cell-Design’
 Process Control
PAST:
o Hull-Cell
o Electroanalytical TechniquesPolarization studies
Conductivity
Titration (reactant conc.)
FUTURE:
L-Cell
Limitations of CAD Software
INPUT
Cell configuration
• Cell
OUTPUT
• Anodes
• Racks and Shields
Operating Conditions
• current or voltage
(DC or Periodic)
• temperature
• flow
Numerical
‘Solver’
Process Properties
• Electrode polarization
• Electrolyte conductivity
• Diffusivity
Often
Missing
• Current distribution
• Deposit thickness distribution
• Potential distribution
• Overpotential (polarization)
• Parasitic reaction rates
• Alloy composition
• Part’s evolving shape
• Deposit texture
Issues with Obtaining Process Data
using Conventional Approach
• Strong dependence on trace additives
• Proprietary formulations
• Lack of fundamental mechanistic understanding
• Laboratory experiments often do not duplicate process
conditions
• Flow dependence
• Cost:
• Potentiostat ~ $ 20,000 - 40,000
• Rotating disk electrode ~ $ 10,000
• PhD investigator ~ $ 100K/yr
i
V
Limitations of the Hull-Cell
• Qualitative
• Current distribution is inherently
inaccurate – varies with material
• No quantitative data
The L-Cell Provides:
 Comprehensive electrochemical process parameters
• Polarization curves
• Kinetics parameters
• Conductivity
 Process diagnostics:
• Indication of process variation due to


additives consumption
contamination
 Tool for process adjustment using a small (50 ml) volume
 Sample plated at a number of different and precisely known
current densities for visual and analytical off-line testing
•
Composition of alloy – partial currents
•
Thickness measurements – current efficiency as f(i)
Fully automated, fast (2 min.) experiment designed for non-experts
Equipment is relatively inexpensive
THE L-Cell – Principle of Operation
• Multi-electrode cartridge and a cell that allows a separate
current feed to each segment
• Electronics to provide a different and precisely measured
current density to each segment
• Automated data acquisition and analysis
Plated cartridge
with segmented
electrodes
Cross-section
The L-Cell: Table-top design
The multi-pin connector
The L-Cell: Table-top design
The L-Cell: Table-top design
Watts Nickel Testing
Design of the L-Cell
‘Cell-Design’ Modeling
Top View (cross-section):
Current distribution –
different between segments
but uniform on each segment
Potential distribution:
Reference electrode
Anode: oxygen evolution
Segmented cathode (plated cartridge)
THE L-Cell – Analytical Approach
Unknowns:
Cathodic polarization curve: iK =f (hA)
Cathodic overpotentials (i0, aC, aA)
Conductivity
Measure:
Segmental current densities
Voltages (including reference electrodes)
Conductivity
Voltage balances
Across the cell
Overpotentials
Data analysis
Butler-Volmer fit
kinetics parameters (i0, aC, aA)
DATA ANALYSIS
Butler-Volmer:
(pure kinetics,
No transport
limitations)


 RT ha
iK  i0 e
e


Mass transport
included:
aA F
a

 RT h  CE  
i  i0 e
 e
CB 



aA F
Here, i0 is measured at CB and:
C
F
RT
ha





h
RT 



a
C
CE = CB
F
h  ha hC
CB
CE
DATA ANALYSIS
Tafel approximation:
 CE  
 
i  i0   e
 CB  

a
C
F
RT
h





 CE 
i
   1
iL
 CB 
 i 
 
i  i0 1   e
 iL  

h
RT 



a
C
F
iL 
nFDCB
C
Equivalent mass transport
boundary layer thickness
DATA ANALYSIS
 i 
 
i  i0 1   e
 iL  

a
C
RT
 
iK 
 i0 e
i

1
i
lL
F
h





aC F
RT
h



ik = Equivalent pure ‘kinetics‘ current derived
from the measured current density, i
The L-Cell System
DATA AQUISITION
0.18
1.25
5.0
8.3
14.2
18.1
29.0
1.09
3.02
22. 6
Cu deposition
Copper sulfate
0.5 M
pH=2
Polarization curve
Kinetics Parameters
Cu deposition
Copper sulfate
0.5 M
pH=2
100 ppm PEG
Comparing
two tests
Cu deposition
Pure Cu
Copper sulfate
w/PEG
0.5 M
pH=2
Compare with:
100 ppm PEG
Specification of acceptable deviation
w/PEG
Copper deposition from copper sulfate
No additives; pH=2
Current density [mA/cm2]
100
80
60
40
20
0
-0.06
-0.11
-0.16
Overpotential, h [V]
-0.21
Copper deposition from copper sulfate
pH=2
2.5
No PEG
Log i [mA/cm2]
2.0
1.5
100 ppm PEG
1.0
0.5
0.0
0
-0.1
-0.2
Overpotential, h [V]
-0.3
-0.4
Nickel Deposition from a standard
Nickel Watts Electrolyte
Current density [mA/cm2]
60
40
20
0
-0.4
-0.5
-0.6
-0.7
Overpotential, η
-0.8
[ V]
-0.9
-1
Nickel Deposition from a standard
Nickel Watts Electrolyte
Log { iK [mA/cm2] }
2
1.6
1.2
0.8
0.4
0
-0.4
-0.5
-0.6
-0.7
Overpotential, η [V]
-0.8
-0.9
-1
Wagner Number
Throwing Power
Summary The L-Cell Provides:
• Process properties: Polarization, Kinetics, Conductivity
–
–
–
–
Use ‘regular production’ solution
By-pass specialized testing – no special expertise needed
No need to scan v-i, or apply transients – use steady-state data
Fast (2 min.), completely automated
• Produces deposit samples plated at different
current densities
• Process diagnostics tool