Compact Discs: Music, Data, Lithography?
Matthew Javener, Dr. John Kirk
Department of Chemistry, University of Wisconsin-Stout
Background
Polymer Advantages and Disadvantages
• This experiment was designed to determine whether or not simple adhesives could be used in combination
with a compact disc as a soft lithography method
• Soft lithography is an expensive process which leads to many young students never learning how it is done
• The nature of this process makes it unique and useful in many aspects of life such as:
Polymer
Cost
Wood Glue
Biotechnology, Electronics, Optics, and Biochemistry
White Glue
Introduction to Compact Discs
• Compact discs have many different uses such
as music and data storage
• The information stored on the disc is done so in
small pits stamped into the polycarbonate layer
• Soft lithography is a low cost method for the
formation of nanostructures
• The process involves stamping nano- or microstructures into a polymer to form a pattern
Graphic layer – above data layer
Lacquer layer – above data layer
Reflective layer – above data layer
Polycarbonate layer – data layer is on top
$1.67
• Degrades at high
magnification with SEM
$0.97
• Easily removable
• Low Cost
• Low viscosity
• Degrades at high
magnification with SEM
• Slow curing (3 hr. approx.)
$1.97
• Low Cost
• High viscosity
• Fast curing (30 min approx.)
Successful vs. Unsuccessful
Start with master
Polyvinyl Acetate (PVA)
• Wood glue is a
Soft lithography process
There are several layers to a compact disc
Disadvantages
• Fast curing (1 hr. approx.)
• Easily removable
• Low Cost
Introduction to Soft Lithography
Tacky Glue
Advantages
possible polymer to
use for lithography
• This image shows
that the wood glue
forms the reverse
image of the disc
Pour on elastomer
Vinyl acetate monomer
Polyvinyl acetate polymer
• PVA is the polymer that is present in each of
the three glues that were used in this
experiment
Wood glue magnified 3000x
• White glue is a
Remove polymer
possible polymer to
use for lithography
Allow to polymerize
• This image shows
that the white glue
forms the reverse
image of the disc
Uses for soft lithography
Biotechnology – this process gives people the
ability to pattern complex molecules that are
associated with biology
Electronics – this process allows people to
reproduce very small features on electronics
quickly and with little cost
Data Layer of Compact Disc magnified 3000x
Step 1 – Removing
Protective Layers
• Duct tape was pressed firmly
against the top layers and then
peeled off
Step 2 – Applying
Different Polymers
• Common adhesives
(polymers) were applied to the
exposed surface of the disc
Elmer’s Glue
Wood Glue
Tacky Glue
• Each polymer was allowed to
cure overnight
Outer layers removed using duct tape
• After the polymers were cured
they were removed from the
surface
• This process was done several
times to obtain the clearest
surface possible
• Care was taken to avoid
scratching the features on the
polymer
• The polymers that were
peeled off were coated with
gold and examined under the
microscope
• The polymers had to be
examined at slow scan speeds
and lower magnification to
avoid destruction of the
surface
• Once images were taken they
were compared to determine
whether or not the polymer
produced a reverse image of
the disc
• Cross-links form when one polymer chain is
connected to another chain
Elmer’s glue magnified 2370x
• Tacky glue was an
unsuccessful polymer
to use for lithography
• This image shows
no sign of the data
layer from the disc
due to the high
viscosity of the
polymer
Step 3 – Examining
Products
• The disc was coated with a
thin layer of gold and
examined under a scanning
electron microscope
• Although these glues are each made of the
same polymer they act differently because of
the formation of cross-links
Tacky glue magnified 3000x
Cross-linking between two polymer chains
• Cross-links can form at different rates
depending on what other chemicals are
present in the glue
• The more cross-linking that is present the more
dense the material will become
Conclusion
• Soft lithography can be done using a compact disc and readily available polymers
• With a more viscous polymer the chance is greater that the lithography will work
• Care should be taken when imaging these types of polymers to avoid damaging the structure
• The process done throughout this experiment would be an excellent way to teach young students about
lithography
Acknowledgments
I would like to extend a special thanks to the follow people for their help on this experiment
Dr. Ray for his help on experimental design
Jack Stransky for his help teaching me how to use the SEM