Electroplating Plastic And the Affects of F, B, and H Type Graphite
The purpose of our research project was to determine what effect different types
of pencil graphite had on the ability to electroplate copper. We used three different types
of graphite, each having their own purpose (one for points, one for blackness, and one for
hardness). We electroplated each type five times keeping all of our variables the same
except for what type of graphite we used. We calculated theoretical yield of copper
plated using plating duration and amps. We also drew conclusions from the visual aspect
of the plating based on how much surface area was copper plated. We compared our
experimental yield of copper with our theoretical and drew conclusions from that.
In our project we electroplated copper onto plastic where positive copper ions,
Cu+2, were platted onto a cathode, which was negatively charged. In our project two
solid copper anodes oxidized into copper ions that were reduced and then platted onto the
cathode (1). The solid copper anodes oxidized as follows: Cu° (s) Cu+2 (aq) + 2e-. The
copper anode loses mass during the plating process because it oxidized to copper ions
replenish the copper ions lost in the sulfate solution (1).
The solution that we used to plate our cathode was mainly made up of copper (II)
sulfate (Cu+2SO4-2). The copper ions within the solution were reduced from a copper
Cu+2 ion to Cu0 on the cathode. The reduction reaction for this is Cu+2 (aq) + 2e-
Sulfuric acid, H2SO4, was also put into the bath solution to increase conductivity
and to prevent precipitation of copper (II) sulfate. Brighteners were used during the
plating process and had to be replenished. The brightener gives the copper being plated
onto the cathode a smooth lustrous deposit (2).
There was a current running through this whole system where electrons were
flowing from the anode to the cathode as seen in Figure 1 (3). The ions then travel
through the solution to complete the circuit (3). This is shown in Figure 1.
The flow of current was measured in amperes where 1 amp equals the passage of
1 coulomb which is 6.24x1018 per second (3). Our current was equal to 0.8A which
equals 0.8 coul/sec. We plated for 10 minutes at 0.8 amps. So the equation for calculating
theoretical yield of copper platted is:
0.8 coul/sec x 600 sec x 1F/96500coul x 1 mole e- /1F x 1 molCu/2mole e- x 63.6g Cu/1
The quantity of copper platted was proportional to the amount of coulombs passed
through the wire during the plating process (3).
In our project we used different types of graphite as a plating surface. We used F,
B, H, type pencil graphite. The composition of the graphite is measured by F which is
used to measure how fine a point can be used, and B which determines the blackness of
the pencil graphite, and H which is the hardness of the graphite in the pencil. In our
project we compared how well each different type of graphite plated. Manufacturers mix
different amounts of powdered clay into the graphite to achieve different hardness of
pencils. Carbon black is also used to create pencils with different darkness (6).
Question: How will using different types of graphite: H, B, and F affect how well copper
plates onto the graphite design on the plastic.
We began by buffing up a small 7 x 7 cm plastic sheet with a piece of coarse
sandpaper keeping the buffing technique constant. Matt buffed the plastic using ten
strokes in each direction with equal pressure using 100-c sandpaper. We then weighed
the plastic and recorded the initial weight. Using a soft-graphite pencil, we drew a design
on the plastic card (a 5 x 5 cm design) making sure the design was bold and connected in
all places. We then attached a copper wire electrode to the plastic. We placed the plastic
on a paper towel in the fume hood and brushed silver conducting paint (Electrode #415)
on the plastic in order to connect the copper wire electrode joint to the graphite drawing.
We then re-weighed the plastic and recorded the final mass. After that we hooked up the
plating bath as shown in the picture below and added 5 mL of brightener to the solution:
Copper sulfate, 6 M sulfuric acid, 0.1 M hydrochloric acid. We attached the wire on the
plastic to the alligator clip. We started the aquarium bubbler and set the current to 0.80
amperes. We then plated for 10 minutes maintaining a constant current. When the
plating was complete we washed the plastic to remove the excess solution and weighed
the final product. We then calculated the theoretical yield and compared our
experimental yield to that. From observing the different varieties of graphite we
electroplated we analyzed the difference of different types of graphite on the
Figure 2 Comparison of Mass of Copper Plated to
Total Mass before plating
Mass (g) Mass before plating
0.6 Mass Cu
F B H F B H F B H F B H F B H
Test 2 Test 3 Test 5
Test 1 Test 4
Type of graphite
This graph compares the mass differences between copper plated and total mass
before plating. The total mass before plating includes the mass of the plastic, graphite,
silver paint, and copper wire. We subtracted the mass before plating from the final mass
that we recorded to get the mass of the copper. This graph helps determine whether or
not the mass of our cathode being plated has to do with how much copper is plated onto
it. In this graph all of the masses before plating were relatively the same and the copper
plated onto them had no direct relation to their similarities in mass. In test 3 however the
mass of the copper plated onto the cathode was almost two times the amount of any of
the other tests.
Figure 3 Comparison of Theoretical Yield to
Experimental Yield of Copper
Mass (g) Theoretical Yield of
0.15 Mass Cu
F B H FBH FBH FBH F B H
Test 2 Test 3
Test 1 Test 4 Test 5
Type of Graphite
Figure 3 compares the theoretical yield of copper platted onto the plastic surface
to the experimental yield that we recorded. In tests 1 and 2 and 4 the experimental yield
was relatively close to the theoretical yield that was calculated. The calculated yield was
0.158g of copper. Another thing that all of these tests had in common was that every
single test was lower than the theoretical yield except for the H pencil used in test 2
which was only a little above the theoretical yield. Test 4 stands out the most with the
experimental yield being drastically different than the theoretical. The B pencil alone
was more than double the weight of the theoretical yield. In test 2 our B pencil graphite
was plated with 0.131g of copper, while in test 3 was plated with 0.333g of copper.
Before we did test 5 we added 5 mL of brightened which could have effected the amount
of copper plated onto the graphite which gave us a recording of experimental yield of a
higher mass than the theoretical yield with every kind of pencil graphite.
Figure 4 Electroplated Plastic
Graphite F Graphite B Graphite H
Figure 4 is shows plated pieces of plastic arranged by which test they were done
during, and which type of graphite we used. The first column is all of the F graphite
tests, the second is the B, and the third is the H. The first row shows all three of each
different pencil graphite in Test 1. The second row shows all three of each different
pencil graphite in Test 2 and so on down to Test 5. The one type of pencil graphite that
always plated very well was the B pencil in the second column which always plated at
least half of the graphite surface, while the other graphite types in columns one and three
most often plated more than a tenth of the surface. Test 1 of H also plated the graphite
area almost completely. Test 1 of F also plated most of the surface, but the rest of the
tests barely plated any surface onto the plastic.
The purpose of our research project was to determine whether or not the different types
of pencil graphite: F, B, and H, had an effect on how each different type plated copper.
As shown in Figure 3, the results were not conclusive, but further testing could be done to
achieve a more accurate result. We determined through five different electroplating tests
that F, B, and H graphite pencils plated about the same amount of copper. Figure 3
clearly shows experimental yield of copper plated was very close to theoretical yield.
However, Test 3 for all three types of graphite did not follow the theoretical trend. Test 3
showed copper masses of almost double all of the other tests in every case. The data in
Test 3 seem so off that conclusions couldn’t be drawn from the data collected. However,
the only variable that could have made a difference is that I was not there on that testing
day, so my partner may have done something different than we did together. On the
visual aspect of our plating, the B graphite pencil always plated more surface area than
any of the other pencils during that particular test. Throughout all of the tests the B
graphite pencil plated at least half of the graphite design while the others did not even
though the time and amps were kept the same for all. Although the mass of copper plated
onto each piece of plastic was relatively similar, the B graphite consistently plated more
surface area than any of the other types of graphite. The B graphite was more conductive
than the F and the H and clearly is a different kind of graphite. Further electroplating
tests could be done with copies pencils or maybe all H type pencils which have different
harnesses H, H2, H4, H6 as well as comparing real graphite which Mrs. Fruen has to that
which is put into pencils.
(1) Weil, Rolf, "Electroplating of Metals,” (2001) http://www.accessscience.com
Available from Access Science Date Accessed 21 April 2005.
This article discusses the process of electroplating and some of the uses.
Essentially a circuit is sent through a power-source, in our case an amp meter, a
cathode, anode, and some sort of electric conducting solution. The thing being
plated is hooked up so that negative charges can flow through it, while the anode
is positive. The solution in which all of this is placed has to contain ions of the
metal that need to be deposited onto the cathode. Some instances where
electroplating is used in circuit boards, jewelry and plating in general because of
its wear resistance and hard coating, and conductive abilities.
(2) J. Hill, Chemistry For Changing Times. MacMillian Publishing Company, New
York, (1992), : 210-211. Date Accessed 21 April 2005.
These pages discuss electrochemical cells and describe how oxidation occurs.
The electrode where oxidation occurs is called the anode, and reduction occurs in
the cathode. In the example in the book there is a zinc anode which is oxidizing
and a copper cathode which is reducing with copper ions. This example shows
how the solution of copper sulfate conducts the current through which the power
source is sent through, and therefore has the ability to run a light bulb.
(3) Allen J. Bard, "Electrolysis,” (2001) http://www.accessscience.com Available from
Access Science Date Accessed 21 April 2005.
This article discusses how current travels through reactions at electrodes with an
electrolyte. The power supply is connected to the electrolysis cells, in our case
it’s the two copper anodes, which is immersed in a liquid that can conduct
electricity through ion movement. This article also discusses the oxidation-
reduction reaction occurring in the electroplating process. Reduction reactions
occur where substances add electrons, the cathode, and oxidation reactions where
species lose electrons, the anode. Some applications of this process are: industrial
synthesis of chemicals, electroplating of metal, metallurgical extraction, refining
of metals, and metal finishing. This article discusses further about the current
which is measured in amperes which flow through the electrolysis cell, and that
the quantity of a substance produced or consumed in an electrode reaction is
proportional to the quantity of electricity.
(4) Chin, Barry, “Barrier and Seed Layers for Damascene Copper Metallization,” Solid
State Technology (1998)
http://search.epnet.com/login.aspx?direct=true&db=aph&an=848929 Available from
EBSCO Date Accessed 21 April 2005.
This article discusses the benefits of electroplating over copper etching and other
processes. The process of electroplating is used for many different purposes but
such purposes as computer circuit boards is particularly efficient because circuit
can be produced directly instead of etching. It discusses that copper has low
resistivity and high electromigration resistance which are beneficial for its uses.
Copper filling however is a much harder process in which variables must be
controlled more carefully and technique must be flawless because of build up
possibilities and possible gap formations to disconnect a circuit.
(5) Alvin J. Salkind, "Wet cell,” (2000) http://www.accessscience.com Available from
Access Science Date Accessed 21 April 2005.
This article discusses the uses of wet cells in which cells such as copper would be
places in a copper sulfate solution, and an outer cell of zinc would be placed out
side of the copper electrode. The outer zinc shell would dilute the copper solution
to a more suitable copper sulfate distribution. In Lalande-Chaperon cell there is a
zinc anode and a cupric oxide cathode placed in an aqueous solution of sodium
hydroxide as the electrolyte. The same reaction occurs in this process as does in
our electroplating, but instead the cupric oxide cathode is converted into metallic
copper within the sodium hydroxide, and the zinc anode reduce the hydrogen
evolution to control the aqueous solution that the cupric oxide is reacting with.
(6) Chemical and Engineering News, “Pencils and Pencil Lead,” (2001), p.1-4,
This article discusses what the different types of pencil graphite mean.
Specifically this article discusses what F, B, and H pencils are used for. F pencil
graphite is used for fine points. B pencil graphite is used for different blackness
of the graphite. And the H pencil graphite determines how hard the pencil
graphite is. Manufactures can change these qualities with different amounts of
clay and carbon.