1. A Novel Device for Plating Process Diagnostics
‘L-Cell’
A Novel Device for Plating Process Diagnostics
L-Chem, Inc.
Shaker Heights, OH 44120

2. Introducing a novel, multi-purpose device that provides:
Process parameters
Process diagnostics
Fully automated
No expertise required
Fast (2 min./test)

3. OUTLINE Rationalle and need Current tecnology and its defficiencies
The L-Cell - principles and description
Examples
Conclusions

4. Issues in Plating Predictive Design Meeting Specs., Optimization
Process Control and Maintenance
Environmental and Health
New Materials

5. } L-Cell Available Tools FUTURE: PAST: Predictive Design
Optimization
Process Control }
Computer Aided Design Software - ‘Cell-Design’
PAST:
L-Cell
FUTURE:
Hull-Cell
Electroanalytical Techniques-
Polarization studies
Conductivity
Titration (reactant conc.)

6. Limitations of CAD Software
INPUT
Cell configuration
Cell
Anodes
Racks and Shields
OUTPUT
Current distribution
Deposit thickness distribution
Potential distribution
Overpotential (polarization)
Parasitic reaction rates
Alloy composition
Part’s evolving shape
Deposit texture
Operating Conditions
current or voltage
(DC or Periodic)
temperature
flow
Numerical
‘Solver’
Process Properties
Electrode polarization
Electrolyte conductivity
Diffusivity
Often Missing

7. 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
Rotating disk electrode ~ $ 10,000
PhD investigator ~ $ 100K/yr i V

8. Limitations of the Hull-Cell
Qualitative
Current distribution is inherently inaccurate – varies with material
No quantitative data

9. 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

10. 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

11. The L-Cell: Table-top design

12. The multi-pin connector

13. The L-Cell: Table-top design

14. The L-Cell: Table-top design
Watts Nickel Testing

15. Design of the L-Cell ‘Cell-Design’ Modeling Top View (cross-section):
Anode: oxygen evolution
Segmented cathode (plated cartridge)
Current distribution – different between segments but uniform on each segment
Potential distribution:
Reference electrode

16. 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)

17. DATA ANALYSIS Butler-Volmer: Mass transport included: CE = CB CB CE
(pure kinetics, No transport limitations) CE
= CB
Mass transport included: CB CE
Here, i0 is measured at CB and:

18. DATA ANALYSIS Tafel approximation:
Equivalent mass transport boundary layer thickness

19. DATA ANALYSIS
ik = Equivalent pure ‘kinetics‘ current derived from the measured current density, i

20. The L-Cell System

21. DATA AQUISITION
0.18
1.25
1.09
29.0
18.1
14.2
8.3
5.0
22. 6
3.02

22. Cu deposition Copper sulfate 0.5 M pH=2 Polarization curve
Kinetics Parameters

23. Cu deposition
Copper sulfate
0.5 M
pH=2
100 ppm PEG

24. Comparing two tests Cu deposition Copper sulfate 0.5 M pH=2
Compare with:
100 ppm PEG
Pure Cu
w/PEG

25. Specification of acceptable deviation
w/PEG

26. Copper deposition from copper sulfate No additives; pH=2

27. Copper deposition from copper sulfate pH=2
No PEG
100 ppm PEG
Log i [mA/cm2]

28. Nickel Deposition from a standard Nickel Watts Electrolyte
Overpotential, η [V]

29. Nickel Deposition from a standard Nickel Watts Electrolyte
Overpotential, η [V]

30. Wagner Number

31. Throwing Power

32. 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