Characterization of Electrodeposited Copper Foil Surface Roughness for Accurate Conductor ...

89 Pages·2015·1.68 MB·English

by  Michael B. Griesi

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Theses and Dissertations
12-15-2014
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Michael B. Griesi
University of South Carolina - Columbia
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Griesi, M. B.(2014). Characterization of Electrodeposited Copper Foil Surface Roughness for Accurate
Conductor Power Loss Modeling. (Master's thesis). Retrieved from https://scholarcommons.sc.edu/etd/
2958
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CHARACTERIZATION OF ELECTRODEPOSITED COPPER FOIL SURFACE
ROUGHNESS FOR ACCURATE CONDUCTOR POWER LOSS MODELING

by

Michael B. Griesi

Bachelor of Science
University of South Carolina, 2013

Submitted in Partial Fulfillment of the Requirements

For the Degree of Master of Science in

Electrical Engineering

College of Engineering and Computing

University of South Carolina

2014

Accepted by:

Paul G. Huray, Director of Thesis

Olufemi B. Oluwafemi, Reader

Lacy Ford, Vice Provost and Dean of Graduate Studies
© Copyright by Michael Griesi, 2014
All Rights Reserved.
ii
DEDICATION
I dedicate this thesis to my wife Jessica. It was her love, support, understanding
and patience that made this pursuit possible. I will be forever grateful.

iii
ACKNOWLEDGEMENTS
My deepest gratitude goes to my professor, advisor and committee chair Dr. Paul
Huray. His passion for understanding the curious and nuanced intricacies of
electromagnetic phenomenon is both inspiring and enlightening. It was through this
passion I found a trusted mentor, leader and friend in our shared pursuit of understanding.
Of particular importance to the completion of this thesis were Dr. Huray’s integral
research and development of the Huray surface roughness model accompanied by his
detailed instruction provided throughout his lectures and publications.
A special thanks to my committee member Dr. Olufemi (Femi) Oluwafemi whose
contributions to developing the snowball model provided practical relevance and
legitimacy to the conclusions and impact of this thesis. Furthermore, his feedback was
both motivating and constructive.
I especially want to thank John Fatcheric and Lee Lesher of Oak-Mitsui who
contributed a significant amount of time explaining the process of manufacturing
electrodeposited copper foil and providing a plant tour. Furthermore, they supplied most
of the material and measurement tools for this research. The conclusions of this thesis are
thanks to John and Lee’s willingness to share their knowledge and resources.
I also want to thank Stephen Hall, who generously contributed constructive
feedback for focused and practical content. As well, I would like to thank Christine Jones
for graciously sharing additional VNA measurements and test board specifications that
were critical for these conclusions. Thank you all.
iv
ABSTRACT
As computer data rates have increased, designers observed that the standard
models for estimating the impact of copper foil surface roughness on conductor loss are
limited to a few GHz. The more recent snowball model (a “snowball” estimation of the
Huray Model) has demonstrated improved conductor loss predictions up to 50 GHz by
estimating the necessary parameters using reasonable assumptions about the geometric
surface features of electrodeposited copper foil. Since then, the Huray Model has been
incorporated into commercial electromagnetic field simulators. However, a standard
method of characterizing the electrodeposited copper foil used in high-speed circuits to
directly implement the snowball model has not yet been fully established. Therefore, the
primary objective of this thesis was to develop a method of more accurately
characterizing the geometric parameters of electrodeposited copper foil surfaces for
accurate conductor loss modeling as defined by the snowball model.
This thesis demonstrates the first methods of directly characterizing
electrodeposited copper foil surface roughness to obtain snowball model parameters.
Additionally, this research further legitimizes the analytic form of the snowball model as
it pertains to scattered power, demonstrates the practical impact of its parameters, and
reveals a source of existing irregularities between the estimated model parameters and
actual performance measurements.
v
PREFACE
This work is divided into six chapters. Chapter one introduces the motivation and
reasons for this research. Chapter two reviews the history of conductor loss modeling,
introduces electrodeposited copper foil and recent developments in conductor loss
modeling. Chapter three meets the primary objective of this research by demonstrating
methods for characterizing the surface of electrodeposited copper foil for accurate
conductor loss modeling with results. Chapter four demonstrates a method for
implementing the characterized parameters in commercially available simulation tools.
Chapter five considers some limitations and concerns for the characterization methods
described and alternatives measurements. Chapter six concludes with significant
takeaways and recommendations for future work.
vi
TABLE OF CONTENTS
DEDICATION ....................................................................................................................... iii
ACKNOWLEDGEMENTS ........................................................................................................ iv
ABSTRACT ............................................................................................................................v
PREFACE ............................................................................................................................. vi
LIST OF TABLES .................................................................................................................. ix
LIST OF FIGURES ...................................................................................................................x
LIST OF SYMBOLS ............................................................................................................. xiii
LIST OF ABBREVIATIONS .....................................................................................................xv
CHAPTER 1: INTRODUCTION ..................................................................................................1
CHAPTER 2: BACKGROUND ...................................................................................................3
2.1 ELECTRICAL CONDUCTOR LOSSES IN HIGH-SPEED TRANSMISSION LINES .............3
2.2 THE MORGAN-HAMMERSTAD EMPIRICAL FIT .......................................................4
2.3 PROBLEMS WITH THE MORGAN-HAMMERSTAD EMPIRICAL FIT ............................6
2.4 ELECTRODEPOSITED COPPER FOIL.......................................................................11
2.5 THE SNOWBALL MODEL ......................................................................................15
2.6 OBJECTIONS TO AND PROBLEMS WITH THE SNOWBALL MODEL ..........................17
CHAPTER 3: COPPER FOIL SURFACE CHARACTERIZATION ..................................................24
3.1 IMPACT OF SNOWBALL MODEL PARAMETERS ON CONDUCTOR LOSS ..................24
3.2 CHARACTERIZING TREATED COPPER FOIL: 𝑎 AND 𝑁⁄𝐴 ..............................27
𝑖 𝑖 𝑓𝑙𝑎𝑡
3.3 CHARACTERIZING UNTREATED COPPER FOIL: 𝐴 ⁄𝐴 ..............................34
𝑚𝑎𝑡𝑡𝑒 𝑓𝑙𝑎𝑡
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CHAPTER 4: USING CHARACTERIZED PARAMETERS IN SIMULATION TOOLS .......................42
4.1 AN EFFECTIVE SNOWBALL RADIUS .....................................................................43
4.2 PERFORMANCE EXPERIMENTS .............................................................................45
CHAPTER 5: DISCUSSION .....................................................................................................52
5.1 CONCERNS AND ALTERNATIVES ..........................................................................52
5.2 KNOWN LIMITATIONS OF THIS RESEARCH ...........................................................53
CHAPTER 6: CONCLUSION AND FUTURE WORK ..................................................................56
6.1 CONCLUSION .......................................................................................................56
6.2 FUTURE WORK ....................................................................................................57
REFERENCES .......................................................................................................................58
APPENDIX A – PERIODIC INTERPOLATION PSEUDOCODE ....................................................60
APPENDIX B – MATLAB CODE FOR OAK-MITSUI IMAGE ANALYSIS .................................61
APPENDIX C – MATLAB CODE FOR GOULD IMAGE ANALYSIS .........................................64
APPENDIX D – MATLAB CODE FOR 3D MICROSCOPE DISTRIBUTION BINNING ................67
APPENDIX E – MATLAB CODE FOR AVERAGE DISTRIBUTION BINNING ............................69
APPENDIX F – PYTHON CODE FOR COMPOSITE SIMPSON’S RULE .......................................71
APPENDIX G – DERIVATION OF EDDY CURRENT EQUATION ...............................................73

viii
LIST OF TABLES
Table 2.1 Conductor Surface Parameters of the Snowball Model .....................................16
Table 3.1 Drum Side 𝐴 ⁄𝐴 ...................................................................................39
𝑚𝑎𝑡𝑡𝑒 𝑓𝑙𝑎𝑡
Table 3.2 Matte Side 𝐴 ⁄𝐴 ...................................................................................39
𝑚𝑎𝑡𝑡𝑒 𝑓𝑙𝑎𝑡
Table 4.1 Microstrip Model Dimensions ...........................................................................46
ix