Adhesive body comprising conductive polymer-metal complex and substrate and method for forming the same, conductive polymer-metal complex dispersion liquid, method for manufacturing the same and method for applying the same, and method for filling hole using conductive material
09622346 ยท 2017-04-11
Assignee
Inventors
- Jin Kawakita (Ibaraki, JP)
- Toyohiro Chikyo (Ibaraki, JP)
- Yasuo Hashimoto (Ibaraki, JP)
- Barbara Horvath (Ibaraki, JP)
Cpc classification
C08G2261/43
CHEMISTRY; METALLURGY
C09D201/00
CHEMISTRY; METALLURGY
C08L65/00
CHEMISTRY; METALLURGY
C09J165/00
CHEMISTRY; METALLURGY
H01L23/49883
ELECTRICITY
C08L65/00
CHEMISTRY; METALLURGY
H05K1/097
ELECTRICITY
C09J2301/408
CHEMISTRY; METALLURGY
C08G2261/3223
CHEMISTRY; METALLURGY
Y10T428/24339
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
H05K1/095
ELECTRICITY
International classification
H05K1/09
ELECTRICITY
H01L21/768
ELECTRICITY
C09D201/00
CHEMISTRY; METALLURGY
Abstract
A conductive polymer-metal complex becomes to be adhered simply and strongly on the surface of a substrate such as PTFE. By subjecting a solution containing a monomer which provides a conductive polymer, an anion, and a metal ions such as Ag.sup.+, Cu.sup.2+, Cu.sup.+ and the like to an irradiation with light having an energy required for exciting an electron to an energy level capable of reducing the metal ion, such as ultraviolet light, under an appropriated condition, thereby precipitating the conductive polymer-metal complex as being dispersed in the reaction liquid. By supplying this dispersion liquid onto various substrates, the complex microparticles in the dispersion liquid enter into and mate with the narrow holes on the surface of the substrate. As a result, the complex precipitate formed on the surface of the substrate and the substrate can be adhered strongly to each other.
Claims
1. An adhesive body comprising a conductive polymer-metal complex and a plastic substrate, wherein the conductive polymer-metal complex comprises an organic conductive polymer and metal nanoparticles having a diameter of 5 nm or more and less than 100 nm, wherein at least a part of the metal nanoparticles is exposed on a surface of the organic conductive polymer; wherein the complex is adhered to a surface of the plastic substrate comprising narrow holes having a size of 5 nm or more; and the complex comprises microparticles having a diameter of 5 nm to 500 nm in the narrow holes on the surface of the plastic substrate adhering the complex to the surface of the plastic substrate.
2. The adhesive body comprising the conductive polymer-metal complex and the plastic substrate according to claim 1, wherein the narrow holes have a size of 5 nm or more and 1000 nm or less.
3. The adhesive body comprising the conductive polymer-metal complex and the plastic substrate according to claim 1, wherein the microparticles are bound to each other.
4. The adhesive body comprising the conductive polymer-metal complex and the plastic substrate according to claim 3, wherein the binding of the microparticles of the complex to each other occurs via Van der Waals' force or a hydrogen bond.
5. The adhesive body comprising the conductive polymer-metal complex and the plastic substrate according to claim 1, wherein the organic conductive polymer is an organic polymer of a straight chain, aromatic, heterocyclic compound or a heteroatom compound having a conjugation structure.
6. The adhesive body comprising the conductive polymer-metal complex and the plastic substrate according to claim 1, wherein the organic conductive polymer is a polymer of a monomer selected from the group consisting of pyrrole, 3,4-ethylenedioxythiophene and aniline.
7. The adhesive body comprising the conductive polymer-metal complex and the plastic substrate according to claim 1, wherein the metal is at least one metal selected from the group consisting of gold, platinum, palladium, ruthenium, iridium, silver, copper, nickel, iron, chromium, zinc, cadmium, tellurium, tin and lead.
8. A method for forming the adhesive body comprising the conductive polymer-metal complex and the plastic substrate according to claim 1, said method comprising adhering a conductive polymer-metal complex dispersion liquid wherein microparticles of a conductive polymer-metal complex comprising an organic conductive polymer and metal nanoparticles with at least a part of the metal nanoparticles being exposed on a surface of the organic conductive polymer is dispersed in a solvent to a substrate.
9. The adhesive body comprising the conductive polymer-metal complex and the plastic substrate according to claim 1, wherein the plastic is selected from the group consisting of an acrylonitrile butadiene styrene (ABS) copolymer, an olefin resin, polypropylene, polyimide, polytetrafluoroethylene, polyvinyl chloride and polyethylene terephthalate.
Description
BRIEF DESCRIPTION OF DRAWINGS
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DESCRIPTION OF EMBODIMENTS
(51) When synthesizing a conductive polymer-metal complex employed in the present invention, a complex of a metal and a conductive polymer is precipitated at a high rate by being assisted by light. Typically, a solution (in acetonitrile, ethanol, water and the like) containing a monomer (pyrrole and the like) serving as a starting material for the conductive organic polymer as well as an anion and a metal ion receives a substrate (silicon, germanium, III-V group semiconductor, oxide semiconductor, glass plate and the like), and is irradiated with light having an energy required for exciting an electron to an energy level capable of reducing the metal ion irradiation. By means of this light irradiation, a reaction involving simultaneous progression of oxidizing polymerization of a conductive polymer from the organic monomer and a doping anion and reducing precipitation of the metal from the metal cation is accelerated, in other words, assisted by the light. While the following example employed such an irradiation using ultraviolet light (wavelength of 400 nm or less), light having a longer wavelength may be employed depending on the excitation energy required. It is a matter of course that heat or sound may be used at the same time as far as it is a stimulus capable of exciting the electron equivalently. After a certain time period, the apparatus is taken together with the precipitate thereon from the solution and dried.
(52) As described above, in the synthesis of the conductive polymer-metal complex used in the present invention, the assistance by the irradiation such as light allows the simultaneous precipitation of the metal and the conductive polymer to be achieved at a high rate, and use of such a novel precipitation method enables production of the conductive polymer at a high rate and utilization of a relatively non-noble metal, which are advantage over the prior art technology shown in Non Patent Literature 4.
(53) Although the reaction mechanism of the conductive polymer-metal complex used in the present invention has not completely been elucidated yet, our study suggests that it is a phenomenon unknown before based on generation of a positive hole and an electron within a conductive polymer as a result of excitation by light and the like which leads to progression of potent oxidizing reaction and reducing reaction, as shown in
(54) Based on the reaction mechanism discussed above, it is understood that, when the redox potential of the metal is at an energy position lower than that a high energy rank (for example LUMO) to which the electron in the polymer can reach when excited as shown in
(55) Based on the discussion on the reaction mechanism described above and Examples described below, it is understood that the following monomers and metals can be employed as starting materials for the conductive polymer-metal complex used in the present invention. Monomers: Monomers capable of producing organic polymers of straight chain, aromatic, hetrocyclic compounds, heteroatom compound having conjugation structures. Metals: Gold, platinum, palladium, ruthenium, iridium, silver, copper, nickel, iron, chromium, zinc, cadmium, tellurium, tin, lead and alloys thereof.
(56) Since the conductive polymer-metal complex used in the present invention consists mainly of organic materials, it is expected essentially to be applied to a conductive wiring pattern onto a flexible substrate or a conductive adhesive. Accordingly, the adhesion to various substrates including plastics is one of the important properties. In addition, with regard to utilization in a three-dimensional wiring described in the background technology, the adhesion to the substrate is important. Accordingly, in Examples described below, an adhesion test (tape peel-off test) or a bending test was conducted and their data were obtained.
(57) Since this conductive polymer-metal complex can fill the inside of a TSV densely with a conductive polymer-metal complex having a high conductivity, it can readily construct an electric connection between LSI chips which is highly reliable and enables a highly dense packaging. In addition, since this conductive polymer-metal complex can precipitate the complex of the conductive polymer and the metal not only on the inside of the via but also on various surfaces and the complex thus precipitated can possesses a flexibility, use of the present invention enables formation of flexible wirings and electrodes in various fields including solar cells and EL illuminations. Furthermore, this conductive polymer-metal complex exhibits a satisfactorily adhesion to various substrates, and further enables, by being applied as its dispersion liquid onto the substrate using an inkjet device or dispenser, production of thin layers as small dots, fine wires or any other shapes on the substrate readily with high precision and arbitrariness.
EXAMPLES
Reference Example 1
(58) Using pyrrole, 3,4-ethylenedioxythiophene (EDOT) and aniline as monomers for obtaining a conductive polymer, Cu.sup.2+ and Ag.sup.+ as metal ions and chloride ion (Cl.sup.) for Cu.sup.2+ and nitrate ion (NO.sub.3.sup.) for Ag.sup.+ as anions, ultraviolet light irradiation was performed to precipitate a conductive polymer-metal complex. With varying types and concentrations of the monomers and varying types and concentration of the metal ions, 30 types of experiments were performed. It should be understood that these are merely examples and are not intended to restrict the technical scope of the present invention which is defined in Claims. These experiments were performed using the following experimental conditions and measurement conditions. Typical experimental condition Temperature: Room temperature Solvent: Acetonitrile, ethanol and water Substrate: Glass Ultraviolet light intensity: 50 mW/cm.sup.2 Wavelength: 436 nm, 405 nm, 365 nm (bright line) Precipitation time: 0.5 to 240 min Resistance measurement method Four probe method using Loresta AP MCP-T400 manufactured by Mitsubishi Chemical (While the measurement principle is well known and is not detailed here, reference can be made to Non Patent Literature 6.) Using a method in which the aforementioned substrate was place on the bottom of the container, and received a sample (conductive polymer-metal complex) as being sedimented (precipitated) thereon, the conductive polymer-metal complexes of Experimental No. 1 to 30 in Table 2 were made.
(59) The results of the experiment thus performed are shown in Table 2.
(60) TABLE-US-00002 TABLE 2 Experiment Monomer Monomer Ag.sup.+ Cu.sup.2+ Resistance No. Type mol/L mol/L mol/L 1 Pyrrole 0.5 5 OL 2 Pyrrole 0.2 2 14.14 3 Pyrrole 0.2 1 0.00067 4 Pyrrole 0.1 2 8.54 5 Pyrrole 0.1 1 4.4 6 Pyrrole 0.1 0.5 32000 7 Pyrrole 0.1 0.2 35800 8 Pyrrole 0.1 0.1 68000 9 Pyrrole 0.05 0.5 4280000 10 Aniline 0.2 2 188 11 Aniline 0.2 1 220 12 Aniline 0.1 1 0.649 13 Aniline 0.05 0.5 21 14 EDOT 0.1 1 2080000 15 EDOT 0.05 0.5 OL 16 Pyrrole 0.2 2 13.35 17 Pyrrole 0.2 1 1394 18 Pyrrole 0.1 1 5.96 19 Pyrrole 0.1 0.5 559 20 Pyrrole 0.1 0.2 16100 21 Pyrrole 0.1 0.1 913 22 Pyrrole 0.05 0.5 38.9 23 Pyrrole 0.05 0.1 100.7 24 Pyrrole 0.05 0.05 273 25 Aniline 0.2 2 49000 26 Aniline 0.2 1 OL 27 Aniline 0.1 1 OL 28 Aniline 0.05 0.5 OL 29 EDOT 0.1 1 689 30 EDOT 0.05 0.5 OL
(61) Here, the metal ions (Ag.sup.+ ion and Cu.sup.2+ ion) and the anions were given actually in the forms of CuCl.sub.2, and AgNO.sub.3. The indication OL in the column of resistances in Table 1 means that the resistance could not be determined because it was larger than the possible measurement range.
(62) The photograph of the appearance of an example of the substrate on which a conductive polymer-metal complex is precipitated as described above is shown in
Reference Example 2
(63) The conductive polymer-metal complex used in the present invention and Non Patent Literature 4 were compared in an experiment. The following experimental conditions and measurement conditions were employed. Pyrrole concentration: 0.1 mol/L Metal ion concentration: 0.1 mol/L Anion: NO.sub.3.sup., Anion concentration: 0.1 mol/L Solvent: Acetonitrile Substrate: Glass Reaction time: 60 min
(64) As a result, when using the pyrrole as a monomer and Ag.sup.+ as a metal ion, the resistance of the precipitate obtained precipitation performed for about 1 hour in the method of Non Patent Literature 4 was as substantially high as 10.sup.5 to 10.sup.7. When using Cu.sup.2+ instead of Ag.sup.+, no precipitation of the conductive polymer-metal complex was observed.
(65) On the other hand, when processing the combination of the pyrrole and Ag.sup.+ based on the manufacturing method of the conductive polymer-metal complex used in the present invention, the precipitation for a time period less than 20 minutes while being irradiated with ultraviolet light yielded a conductive polymer-metal complex having a resistance of 0.3 to 0.610.sup.1. When using Cu.sup.2+ instead of Ag.sup.+, a time period of the ultraviolet light irradiation and precipitate less than 10 minutes resulted in a resistance of 0.2 to 0.310.sup.2.
(66) As a result of a comparative control experiment, the conductive polypyrrole itself (PTS anion dope) had a resistance of 0.210.sup.2.
(67) Based on the results of the experiment shown in Table 2 and the like, preferable ranges of the monomer concentration and the metal ion concentration when using pyrrole as a monomer and Ag.sup.+ or Cu.sup.2+ as a metal ion are shown in Table 3. In Table 3, the resistances of a conventional conductive polymer, Cu formed without electrolytic plating and W formed by CVD are shown as comparative controls.
(68) In the conductive polymer-metal complex used in the present invention, the fact that the growth rate of the conductive polymer-metal complex is higher than that of other conductive bodies of the prior art is also one of the characteristics. To show this fact, Table 3 further includes the film growth rate (i.e., the growth rate in the direction of the film thickness).
(69) TABLE-US-00003 TABLE 3 Examples (Summary) Film form- ing Monomer Cation Resistivity rate mol/L Ag.sup.+ mol/L Cu.sup.2+ mol/L cm nm/s Pyrrole 0.1 or Monomer ratio 0.00018 42 more of 5 times or more and 20 times or less Pyrrole 0.05 Monomer ratio 1.8 67 or of 1 time or more more and 10 times or less Comparative Examples (Summary) Polypyrrole 0.36 11 (Note (PTS Dope) 1) Cu Plating 1.67E06 0.5-1 (Note 2) W-CVD 5.3E06 1-8 (Note 3)
(70) Note 1: Data found (the resistivity was obtained by converting the resistance measured by the method similar to that in Reference Example 1 into a resistivity.)
(71) Note 2: Data from Non Patent Literature 2
(72) Note 3: Data from Patent Literature 1 and Non Patent Literature 3
(73) The column of the resistivity of the conductive polymer-metal complex varies depending on the pyrrole concentration and the metal ion concentration. In the column of the resistivity in Table 3, those which were the best in the data in Reference Example 1 within corresponding pyrrole concentration range and metal ion concentration range are indicated. The anion which can be employed in the conductive polymer-metal complex used in the present invention in addition to NO.sub.3.sup., Cl.sup. employed in Reference Example 1 includes I.sup., BF.sub.4.sup. and the like. It is also possible to use various anions such as protonic acid ions (SO.sub.4.sup.2 or ClO.sub.4.sup. and the like in addition to NO.sub.3.sup.), halide ions (F.sup. or Br.sup., as well as its mixture in addition to the aforementioned Cl.sup. or I.sup.), Lowis acid ions (PF.sub.6.sup., AsF.sub.6.sup. and the like in addition to the aforementioned BF.sub.4.sup.), transition metal halides (anions resulting from conversion of FeCl.sub.3 or MoCl.sub.5 possibly into the forms of FeCl.sub.4.sup. or MoCl.sub.6.sup.), organic compounds (those resulting from conversion of a substituent of an organic compounds such as PSS into an anionic one such as SO.sub.3.sup. or TCNQ or TCNE, DDQ and the like in addition to PTS) and the like.
(74) As known from Table 3, the metal conductive body comprising Cu or W formed by the conventional method has an extremely low resistivity. Nevertheless, its extremely slow growth makes it completely impossible to be used in a practical TSV formation and the like.
(75) The conductive polypyrrole itself exhibits a substantially higher resistivity when compared with the conductive polymer-metal complex using Ag as a metal. Although the sensitivity was of that of the complex using Cu, the growth rate was also reflecting an extremely slow growth, which makes the use in the TSV formation impractical.
(76) On the contrary, the conductive polymer-metal complex used in the present invention has a resistivity applicable for a practical use while its growth rate is far higher than that of a conventional conductive material of this type, it enables the formation of the TSV formation and other conductive body formation at a practical speed.
(77) The reason for the smaller resistivity (0.36 cm) of the conductive polypyrrole itself in Table 3 than the resistivity (1.8 cm) of the conductive polymer-metal complex used in the present invention (polypyrrole-copper complex) using copper as a metal can be explained as follows.
(78) The resistivity of polypyrrole varies depending on the type and the concentration of the anion to be doped. Since PTS dope was reported to exhibit the lowest resistivity, it was employed here as a comparative example.
(79) On the other hand, the conductivity (resistivity) of the conductive polymer-metal complex used in the present invention is considered to be dependent on the conductivity of the polypyrrole itself and the metal content. In the polypyrrole-copper complex in Reference Example 1, it is assumed that the chloride ion was doped in the polypyrrole. The chloride ion does not provide a conductivity comparable to that by the PTS anion, and the dope level in Reference Example 1 is considered to be low. In addition, in Reference Example 1 employing copper as a metal, the low copper content (precipitated amount) is considered to be one of the reasons for the conductivity of the complex itself which was lower than that of polypyrrole (PTS dope). In any case, the aforementioned experiment examples indicate that the conductive polymer-metal complex used in the present invention was successful in achieving the aforementioned satisfactory conductivity and growth rate before optimizing the starting material and the precipitate condition sufficiently.
(80) Also for the purpose of clarifying the structure of the conductive polymer-metal complex used in the present invention at nano level, the SEM image of the surface of the precipitated conductive polymer-metal complex was investigated.
(81) Based on these microscopic observation, the growth mechanism, of the conductive polymer-metal complex used in the present invention is suggested. While a polymer tends to grow in one-dimensional direction, a metal (silver here in a typical experiment) tends to grow in three-dimensional direction as being precipitated on the polymer surface. Thus, the metal nanoparticles tend to present exclusively on the surface in a manner covering the surface of the polymer cluster (see
Reference Example 3
(82) An example of the behavior of a reaction system in which both of a light and a heat are employed as energies upon precipitating the conductive polymer-metal complex is shown below.
(83) The substrate employed was a silica glass (880.9 mm), and this substrate was immersed in an acetonitrile solution containing silver nitrate (1.0 mol-dm.sup.3) serving as sources of a metal cation and a doping anion and pyrrole (0.5 mol-dm.sup.3) as an organic monomer. The reaction system was subjected to light irradiation using an ultra high pressure mercury lamp (bright line wavelength: 436 nm, 405 nm, 365 nm) with the intensity being set at 30 mW.Math.cm.sup.2 or 60 mW-cm.sup.2. The reaction system was heated using a hot plate and the temperature was set at 50 C. or 70 C. The temperature of the reaction system when not heated was 30 C.
(84) When the light irradiation was not performed and the heating temperature was changed, the solution remained transparent at 30 C. and 50 C. regardless of the time elapsed. When heated at 70 C. without light irradiation, a black precipitate was obtained and increased along with the time. These findings are in consistent with the report that black agglomeration of silver particles covered with polypyrrole was produced (Non Patent Literature 5).
(85) On the other hand, when the intensity of the light irradiation was changed in a non-heating state (30 C.), when the light irradiation was not conducted, the solution remained transparent regardless of the time elapsed. With a light irradiation intensity of 30 mW.Math.cm.sup.2, the solution became yellowish transparent along with the time, and no change was observed after 30 minutes of the reaction time or later. With an irradiation intensity of 60 mW.Math.cm.sup.2, the time period until the yellow color became deep was short, and a black-mixed silver precipitate was observed after 10 minutes or later, and was increased until 60 minutes later, after which there was no change.
(86) When both of the light irradiation intensity and the heating temperature were changed, a black-mixed silver precipitate was observed, and its production increasing rate tended to be higher as the light irradiation intensity and/or the temperature was raised. Since the precipitate under the light irradiation has a structure in which the surface of the conductive polymer was covered with the microparticles of the metal silver, the silver precipitate was considered to be an agglomeration of such microparticles.
(87) Based on the behavior of the aforementioned reaction system, it was clarified that, in the reaction for forming a complex of a conductive polypyrrole with a metal silver and a metal, a structure in which the silver covers the polypyrrole surface can readily be formed by light irradiation. It was also clarified that the precipitation reaction rate can mainly be improved by heating under the light irradiation.
(88) While both of the light and the heat were employed in the aforementioned Reference Example as energies given for precipitating the conductive polymer-metal complex, it is possible to use both of light and sound. While any sound in general can simultaneously be employed, ultrasonic waves having a frequency of 20 kHz or more are employed preferably. It is also possible to use ultrasonic waves within the range of about 20 kHz to 100 kHz which is employed for example in an ultrasonic washing machine. Using such an irradiation with sound such as ultrasonic waves, it is possible to control the length or the aspect ratio of the polymer constituting the resultant particle as well as the particle size of the metal particle. Such a control utilizes a particle size-reducing effect which is a phenomenon observed frequently when using the ultrasonic waves for dispersing emulsion or dissolving powders in a liquid.
Reference Example 4
(89) In order to investigate the adhesion between the conductive polymer-metal complex used in the present invention and the substrate, a tape peel-off test was performed under the following condition.
(90) In order to prepare a thin sample having a small film thickness, a complex as being dispersed preliminarily in a solution (possibly having a particle size smaller than that in Reference Example 1) was made, and this solution was added dropwise onto various substrates to be subjected to the tape peel-off test and then dried.
(91) More detailed experiment conditions are described below. Solution prepared Pyrrole concentration: 0.2 mol/L Metal (Ag) ion concentration: 1.0 mol/L Anion: NO.sub.3.sup., Anion concentration: 1.0 mol/L Solvent: Acetonitrile (pyrrole was dissolved in 10 ml of acetonitrile) Polymerization processing The aforementioned solution was placed in a cell (small and thin container) having the following structure, and using a light at a bright line wavelength of 436 nm, 405 nm or 365 nm and an intensity of 60 mW/cm.sup.2, the polymerization was performed for 10 minutes at room temperature. Cell structure: Obtained by cutting a 1-mm thick Si sheet and sandwiching the circumference between a 1-mm thick optical glass. Processing for adhering complex to substrate as test subject A solution in which the complex after the polymerization processing was dispersed was added dropwise using a micropipette onto the substrate as a test subject. The volume to be added dropwise was constant at 50. The substrate after adding the solution dropwise was allowed to dry in a draft chamber. The sample was allowed to dry under a lighting condition which was not a complete darkness but an ordinary room light condition for indoor work (under a fluorescent lamp). The quantity of the illumination irradiated during drying when measured by an accumulated light meter was 1 mW or less. Tape peel-off test The tape peel-off test is one of the peel-off tests among the adhesion testing method for plating (JIS-H8504). This test examines the adhesion of a plating by bonding a tape having an adhesiveness onto a plated surface and peeling the tape off rapidly and strongly. The tape peel-off test is suitable generally to a relatively thin plating such as a noble metal plating, and not suitable to a thick plating. Nevertheless, since it is used for a verification test of a final product because it becomes a non-destructive test if the adhesive is satisfactory, this tape peel-off test was employed here for examine the adhesive between the conductive polymer-metal complex of the present invention and the substrate.
(92) The results of the test performed as described above are shown in Table 4 and
(93) TABLE-US-00004 TABLE 4 Substrate Results Remarks ABS resin Polypropylene (PP) Teflon (PTFE) Polyvinyl chloride (PVC) Olefin resin Polycarbonate (PC) Polyethylene X Acrylic resin X Substrate surface dissolution Silicone rubber Plain paper Glossy paper X Metal titanium Glass (surface blast treatment) Glass (non-surface blast X treatment)
(94) As shown in Table 4 and
(95) Some of the substrates exhibited the experimental results indicating that the adhesion was insufficient (x), or substantially poor () (
(96) In any case, the utility of this complex capable of achieving a highly adhesion even with Teflon (Trade Mark) usually exhibiting an extremely poor adhesion only by using a plain adhering method applicable simply to a wide range of the conditions in which the solution in which the complex after the polymerization processing is dispersed is just added dropwise and then dried is considered to be extremely high.
(97) It should be understood that the highly adhesion observed in the results of the adhesion test (tape peel-off test) especially when using as a substrate Teflon (Trade Mark) or polypropylene as a substrate is noteworthy. This understanding is based on the recognition that the surface energy of Teflon (Trade Mark) or polypropylene is low and its adhesion to different materials is poor. Accordingly, in order to know the adhesion of Teflon (Trade Mark), the sectional image was investigated.
(98) Focusing on the fact that in the adhesiveness the conductive polymer-metal complex used in the present invention exhibited a high adhesion to Teflon (Trade Mark) which adhesion to an ordinary material such as adhesives or various paints is known to be extremely poor, a section of the both which are in a adhesion was prepared and its microscopic photograph is shown in
(99) In the photograph, one indicated as embedding resin is one which is used for exposing the section to be observed by embedding a sample in a resin such as an epoxy resin which is then polished. Two pair of the photographs at low and high magnifications are shown because of the reason as follows. Since the material observed here is a novel material and has no established method for preparing a section thereof, no smooth surface was obtained satisfactorily throughout the entire field of vision (the entire field of vision is not focused on correctly). Accordingly, each of the two observed fields of vision was indicated as photographs at low and high magnification with its conditions of section preparation and photographing being consistent with each other as possible, thereby allowing them to be observed as comparable morphologies of the sections.
(100) In the photograph of the section, when viewing the interface between the conductive material which is the conductive polymer-metal complex used in the present invention and the substrate made from Teflon (Trade Mark), it is known that even into extremely fine protrusions and recesses of the substrate the conductive material has entered and the adhesion has been established almost to a level of integration without undergoing any peeling even when viewing the photograph in the right side which is the photograph of the section at the higher magnification. In addition, both of the 2 sections exhibited the states of the adhesion which are completely the same, which suggests that it is highly possible that any other sections are in similar conditions.
(101) It is well known that Teflon (Trade Mark) is not dissolved in an ordinary solvent, and the solvent used for applying and forming this conductive material on the substrate is not able to dissolve as a matter of course. Nevertheless the both are adhesive to each other to a level that there was no gap between the both, which should be noted.
Reference Example 5
(102) The results of a bending test of the conductive polymer-metal complex sticking on substrate of the present invention are shown in
(103) In order to clarify that even when the conductive polymer-metal complex used in the present invention was formed on a pliable material the complex can fully tolerate such a deformation of the substrate without any peeling and maintains the conductivity even in a substantially deformed condition, the conductive polymer-metal complex of the present invention was formed on a paper substrate and subjected to an experiment in which the substrate was deformed intentionally. The conductive polymer-metal complex of the present invention formed on the substrate here was one made from the polymer and the metal employed in tape peel-off test.
(104) The first photograph in
(105) This sample was folded substantially to the extent that the right and the left of the substrate are in an angle of approximately 90, but no peeling was observed as shown in the second photograph in
Example 1
(106) By applying a dispersion liquid of the conductive polymer-metal complex manufactured by the method similar to that in Reference Example 4 to a substrate using an inkjet or a dispenser, a uniform thin layer of this conductive polymer-metal complex can be formed on the substrate with a high precision. The detailed description is made below.
(107) A suspension was manufacture as described below. Solution prepared Pyrrole concentration: 0.5 mol/L Metal (Ag) ion concentration: 1.0 mol/L Anion: NO.sub.3.sup., Anion concentration: 1.0 mol/L Solvent: Acetonitrile (pyrrole was dissolved in 10 ml of acetonitrile) Polymerization processing The aforementioned solution was placed in a cell (small and thin container) having the following structure, and using light at a bright line wavelength of 436 nm, 405 nm or 365 nm and an intensity of 50 mW/cm.sup.2 or more, the polymerization was performed for 10 minutes at room temperature. Cell structure: Obtained by cutting a 1-mm thick Si sheet and sandwiching the circumference between a 1-mm thick optical glass.
(108) By performing the aforementioned processing, a transparent solution was obtained. This solution is a dispersion liquid in which the conductive polymer-metal complex is dispersed.
(109) The SEM image of this dispersion liquid (here the intensity of the irradiated light was 60 mW/cm.sup.2) when dried after being dropped was shown in
(110) While in Reference Example 1 and the like the conductive polymer-metal complex precipitated upon synthesis on the substrate, no such a precipitation occurred in this Reference Example with the dispersion in the reaction solution being maintained. When this dispersion liquid was stored in a refrigerator in 2 weeks, no change was observed, indicating a high storability and stability.
(111) The reason why the aforementioned difference is observed between this Example and Reference Example 1 etc. may exist in the manner of the light irradiation upon the reaction. Thus, in Reference Example 1 etc., the solution was placed in a container whose diameter and depth were not different extremely and then was irradiated with the light. In such a manner of the light irradiation, there is a difference in the light intensity between the solution in front and the solution in back when observed from the direction of the light irradiation, and the reaction employing the light tends to less proceed in back. As a result, the number of the nuclei formed even irradiated with the light in the same quantity is smaller in Reference Example 1 etc., and the growth of the nucleus is more preferential than the formation of the nucleus, resulting in a greater particle. On the contrary, this Example employs the container (cell) in which the reaction occurs has a thickness as extremely small as 1 mm when compared with Reference Example 1 etc., which allows each small part of the solution in the cell to receive the light irradiation at the almost similar intensity when the light is irradiated uniformly from the direction almost perpendicular to the cell plane. As a result, the nucleus is formed in every place in the solution contained in the cell. Accordingly, it is possible that the formation of the nucleus becomes more preferential than the growth of the nucleus in this Example unlike to Reference Example 1, resulting in formation of a larger number of the highly uniform fine particles.
(112) While in the aforementioned example the case employing a cell thickness, of 1 mm was described, other experiment gave the dispersion liquid similar to that described above when using a cell having a thickness of 2 mm or less. While the aforementioned example employed acetonitrile as a solvent for dissolving the starting materials of the reaction, any other solvent can be employed as a matter of course. For example, any solvent capable of dissolving the starting material, i.e., monomer, metal ion and doping anion can be employed including water and ethanol. Here, the solubility of a starting material can be raised usually by a polar solvent. On the other hand, the liquid in which the conductive polymer-metal complex is dispersed may preferably be a non-polar solvent assuming from the solvent for dispersing the metal nanoparticles. Accordingly, a solvent mixture of a polar solvent and a non-polar solvent may definitely be effective for the dispersion liquid.
(113) While the dispersion liquid prepared in this Example contained the minimum components, including the conductive polymer-metal complex, the solvent, remainders of the components added for synthesizing the conductive polymer-metal complex, reaction by-products, other impurities and the like, it is possible to add other components as required. For example, those contemplated are components for further improving the stability of the dispersion liquid such as a surfactant, components for improving or adjusting the application performance of the dispersion liquid or the properties of the dispersion liquid compatible to the requirements by an application instrument, components for preventing corrosion or other adverse effect on instruments for applying the dispersion liquid or subjects of application as well as other components for adding any desirable functions to the dispersion liquid. Also with regard to the timings of the addition of such components, addition at any time is acceptable including addition into starting material for synthesizing the conductive polymer-metal complex, addition immediately after synthesis, addition several hours after synthesis, addition immediately before use, and the like.
(114) When the conductive polymer-metal complex precipitate from the dispersion liquid applied onto the substrate, in addition to the precipitation of the complex as itself already existing in the dispersion liquid, an in-situ polymerization/precipitation of some of the components which were added for synthesizing the complex and remained in the dispersion liquid may occur. When such an in-situ polymerization/precipitation occurs, the adhesion between the substrate and the precipitated complex may be promoted because of the effects involving the growth of the complex in the deeper region of a hole on the surface of the substrate or in the circumference of a protruded part as well as the growth of the complex while being bound or adhered closely to the surface of the substrate. Also in a process of aggregation of the microparticles of the conductive polymer-metal complex in the dispersion liquid, the polymerization may proceed on the surface of such microparticles. It is also possible that, upon aggregation of the conductive polymer-metal complex microparticles in a narrow hole on the surface of the substrate, progression of such a polymerization allows the aggregate to be grown into a larger one, or, even if there is no such a growth by the polymerization, bindings due to hydrogen bond or Van der Waals' force and tangling of microparticles with each other may lead to formation of an aggregate having a shape and a size enabling a function as a closure which is difficult to be pull out of the narrow hole.
(115) While various techniques and instruments can be employed for applying the dispersion liquid thus prepared to a substrate, an inkjet (Non Patent Literature 7) and a dispenser (Non Patent Literature 8) were employed here to validate that by using the dispersion liquid a conductive polymer-metal complex thin layer (including small dots and fine wires) can be formed.
(116) First, the contact angle of this dispersion liquid was measured using several substrate materials, and was found to be 10.21 for a silica glass, 32.10 a polished silicon wafer whose surface was oxidized naturally, 59.33 for a silicone rubber and 83.78 for PTFE.
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(121) As described above, the conductive polymer-metal complex of the present invention dispersion liquid has a high compatibility with existing techniques and instruments for applying thin layers including fine wires and small dots precisely, and can apply a small and flexible conductive line pattern precisely, readily and strongly onto various substrates shown in Reference Example.
Example 2
(122) If it is possible to adhere the conductive polymer-metal complex thin layer, shown for example in Example 1, onto various substrates such as polymers strongly, utilizations in various electric instruments is achieved preferably. Accordingly, an experiment which is further detailed from the experiment in Reference Example 4 was performed, and the interface where the adhering occurs was observed further precisely using SEM and the like.
(123) Commercially available plastic plates (shown in Table 5) such as PTFE were employed as substrates. Pyrrole (manufactured by Kanto Chemical Co., Inc., reagent grade) as a monomer to be polymerized and silver nitrate (AgNO.sub.3, manufactured by Kanto Chemical Co., Inc., reagent grade) as a metal cation (Ag.sup.+) source and a doping anion (NO.sub.3.sup.) source were dissolved in acetonitrile (CH.sub.3CN, manufactured by Kanto Chemical Co., Inc., reagent grade). The concentrations of pyrrole and silver nitrate were 0.2 mol/dm.sup.3 and 1.0 mol/dm.sup.3, respectively. This solution was placed in a cubic container. This solution was irradiated via the side wall of the container made from an optical glass with an ultraviolet light for 15 minutes. As a light source, an ultra high pressure mercury lamp (manufactured by USHIO INC., bright line Wavelength: 436 nm, 405 nm and 365 nm, light quantity: 60 mW/cm.sup.2) was employed. An aliquot (50 mm.sup.3) of the resultant solution was added dropwise onto a board (surface area: 2020 mm.sup.2) and dried to obtain a precipitate.
(124) The adhesion strength between the precipitate and the substrate was evaluated by the peel-off test in accordance with Japanese Industrial Standard (JIS) Z1522. On the surface of the sample having the precipitate adhering onto the substrate, a cellophane tape was stuck and then peeled rapidly off the sample. The conditions of the surface where the tape was stuck and the test surface of the sample were observed.
(125) The surface of the sample after the peel-off test was embedded in the epoxy resin similarly to Reference Example 4, and the section was exposed by slicing and polishing. This section was observed using a scanning electron microscope (SEM, S4800 manufactured by Hitachi High-Technologies Corporation) and an optical microscope (ECLIPSE ME600 manufactured by Nikon Corporation). Furthermore, this section was analyzed by an energy dispersive X-ray spectrophotometer (EDS, EXAM Energy EX-220 manufactured by HORIBA, Ltd.).
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Adhesiveness (%)=[area of precipitate on substrate]/[total area of precipitate on substrate and tape]
(127) When a precipitate exhibits a strong adhesiveness toward the substrate, the precipitate remains on the substrate against the peeling motion of the adhesive tape, thereby exhibiting a high adhesiveness. Table 5 shows the adhesiveness of the polypyrrole-silver complex prepared as described above toward various plastic substrates and the like. A certain kind of the plastic substrate exhibited an adhesiveness of 90% or more. PTFE, which is known especially to show a low adhesiveness generally to various materials because of its low surface energy, exhibited here the adhesiveness as high as 96%. Other polymers exhibited the adhesivenesses of about 70%. The adhesiveness to the acrylic resin substrate was as relatively low as 14%. The surface of the acrylic resin exposed after the peel-off test seemed to be dissolved.
(128) TABLE-US-00005 TABLE 5 Type of substrate Adhessiveness Acrylonitrile butadiene styrene (ABS) 99 copolymer Olefin resin 99 Polypropylene (PP) 97 Polyimide (PI) 96 Polytetrafluoroethylene (PTFE) 96 Polyvinyl chloride (PVC) 94 Polycarbonate (PC) 76 Polyethylene (PE) 67 Acrylic resin 14 Silicone rubber 98
(129) In order to clarify the adhesion mechanism of the conductive polymer-metal complex as a precipitate on a substrate of a plastic etc., the interface structure between the polypyrrole-silver complex prepared as described above and PTFE was investigated below. PTFE was selected here in order to eliminate various chemical factors which may have an influence on the adhering. This is based on the fact that PTFE has generally low reactivities with various materials, and has a low solubility in CH.sub.3CN employed as a solvent in this Example.
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(131) The elemental distribution near the interface of the precipitated complex and the PTFE substrate was investigated by EDS, and the results with regard to fluorine (F) and silver (Ag) elements are shown in
(132) The narrow hole referred herein generally in conjunction with substrates is not always a round hole, and rather present in a form having a narrow and long section, which is to be expressed as a gap or crack. Thus, it should be noted that the narrow hole has various shapes. Since the significance of the discussion on the fine hole diameter relates mainly to the possibility that the microparticle or the dispersion liquid enters into the fine hole, the shorter diameter (which is generally referred to as width in cases of a gap or fissure shape) is significant than the longer diameter. Accordingly, the size or the diameter of the narrow hole, as used herein, means the shorter diameter when the section is in an oval shape, or the width when the section is in an extremely narrow and long shape such as a gap or fissure, unless otherwise specified.
(133) In case of PTFE, the measurement indicated that the sizes of the narrow holes are distributed within the range of about 5 nm to 100 nm. In case of a silicone rubber among other materials, the sizes of the narrow holes are distributed within the range of about 5 nm to 1000 nm. While it is a matter of course that smaller or larger narrow holes than the aforementioned range may exist, a too small narrow hole does not allow the complex to enter into it. Also in case of a larger narrow hole having a size exceeding 1000 nm, the aforementioned adhesion effect can surely be obtained, but in such a large narrow hole any ordinary adhesive can readily enter. Accordingly, in this application, the narrow holes within the range of 5 nm to 1000 nm are focused on.
(134) In order to clarify here that the microparticle of the complex which enters into the narrow hole of the surface of the substrate actually exists in the dispersion liquid of the complex as well as the degree of its size, the dispersion liquid employed was observed using a transmission electron microscope (TEM). The TEM image is shown in
(135) Also in order to investigate whether the Ag nanoparticle is exposed on the surface of the complex microparticle in the dispersion liquid, the dark field electron image of the complex microparticle in the dispersion liquid shown in
(136) Since the dark field electron image becomes brighter when the crystallinity is higher, these 4 gradation parts can be interpreted as described below. The white part is a part in which the Ag nanoparticle is exposed on the surface of the microparticle. The light grey part is a part in which the Ag nanoparticle can be seen via the conductive polymer, i.e., the part in which the Ag nanoparticle is covered with the conductive polymer. Almost blackish dark grey part is a part in which only the conductive polymer can be seen with no Ag nanoparticle in the background.
(137) The black part is the background region having no complex microparticle.
(138) Accordingly, at least a part of the complex microparticle allowed the exposure of the metal nanoparticle from the conductive polymer to be confirmed. This minute structure achieves such a high conductivity of the precipitate of the complex microparticle.
(139) The diameter of the primary particle in the dispersion liquid observed as described above is 5 to 20 nm, and these particles have the particle sizes which are far smaller than the wavelengths of the visible light region. Accordingly, these particles do not undergo light absorption in their nature, and the aforementioned colors should not be observed. However, the dispersion liquid here exhibited a blue color because of the color development by a surface plasmon resonance due to the metal nanoparticle present on the complex particle even in case of such a further smaller primary particle, although the presence of complex particles having larger diameters can not be eliminated.
(140) The distribution of the diameters of the primary particles present in the dispersion liquid is frequently within the range of 5 to 40 nm even when changing the conditions of preparation of the dispersion liquid. It is also possible that by allowing the growth to further proceed for example by prolonging the light irradiation time period, or by allowing the primary particles in the dispersion liquid to aggregate the size of the complex microparticles in the dispersion liquid is further increased and the diameter reaches 100 nm at maximum. Nevertheless, a diameter exceeding 100 nm is not preferable because it does not allow the dispersion liquid to maintain the colloid state, resulting in sediment or state of suspension. On the contrary, a diameter of 100 nm or less is sufficiently small for entering into the narrow holes on the surfaces of various substrates, which allows the mating-based adhesive effect of the conductive polymer-metal complex described above to be exerted.
(141) While the range of the size of the complex microparticles (primary particles) in the dispersion liquid precipitate adhering to the substrate is about 100 nm in the experiment employing PTFE as a substrate as described above, it may vary depending on the dispersion liquid employed or difference in various processing conditions. The upper limit of the range of the size is 300 nm, with about 500 nm at maximum. The lower limit is about 5 nm since the complex microparticles in the dispersion liquid entering into the narrow holes on the surface of the substrate does not become larger than the narrow holes unless it binds to other microparticles outside of the narrow hole or it grows out of the narrow hole and also since even outside of the narrow holes the complex microparticles in the dispersion liquid may remain as it is in the precipitate without binding to other microparticles because of other reasons.
(142) While the size of the metal nanoparticles contained in the complex microparticles in the dispersion liquid or in the precipitate usually does not differ substantially from the size of the complex microparticles in the dispersion liquid containing this metal nanoparticle, it is about 1 nm at minimum and the largest size is less than the size of the complex microparticles containing this metal nanoparticles in the dispersion liquid as a matter of course.
(143) In order to clarify the mating-based adhesive effect of the conductive polymer-metal complex, the aforementioned peel-off test was conducted using a glass plate as a substrate.
Variation Example
(144) In the present invention, a substrate has a cavity as a narrow hole, which serves as a mold when receiving a liquid containing a complex microparticle to allow the complex in a fine wire shape to be formed in the narrow hole. The fine wire thus formed increases the adhesiveness. Since one entering into the narrow hole here is the microparticle of the complex, the hydrogen bond attributable to the polymer in the complex is considered to contribute to the binding force between the microparticles as described above. Nevertheless, it is also possible to obtain a fine wire consisting only of the metal by removing the polymer component by a processing such as an external heating of the entire adhesive body after formation of such an adhesive body. When this heating is performed by allowing a current to run into the complex to generate the heat, the precipitate part serving as a current path (for example, a part employed as a wiring) becomes a pure metal which gives a reduced resistance, but the fine wire part of the complex entering deep into the narrow hole of the substrate does not receive the current, thereby allowing the complex structure to be maintained. In such a case, it is considered that the initial adhesiveness is maintained since the fine wire part entering deep into the substrate is not changed.
(145) When the fine wire of the complex formed by the complex microparticle entering into the substrate has a unique shape, such as a shape in which it bends inside the substrate, it is bigger inside than at entrance, it is branched inside, the fine wire becomes resistant to be pulled out from the substrate, resulting in a further improved adhering force. It is further preferable to allow a narrow hole advantageous for improving the adhesiveness to be formed or added on the substrate surface in addition to utilizing as a narrow hole of the substrate those existing initially on the substrate.
(146) As a further utility of the conductive polymer-metal complex, it is contemplated that on an elastic body such as a rubber the present complex is formed. This complex may be floated up and peeled off when being compressed strongly. Accordingly, when this complex is formed on the substrate which should be assumed to be compressed during use, the complex is formed by the processing in the state where the board of a rubber etc. has been compressed to the possible maximum compression level. By this way, no further compression occurs during use as a product, thereby avoiding problems such as peeling off.
(147) Also when the apparatus for forming a vertical wiring such as a via is one which can readily be deformed such as a rubber, by supplying the dispersion liquid while allowing the diameter of the hole for the vertical wiring to be larger by deforming the substrate, a rapid penetration deep into the substrate utilizing gravity and the like becomes possible. Since this solution undergoes relatively slow precipitation at a low temperature, such a low temperature may be employed to ensure deep penetration without precipitation while enlarging the narrow hole at the same time.
(148) While silver was exemplified in the aforementioned Example as a metal for forming a complex, the present invention poses no restriction to silver, and it is possible to use, for example, copper, platinum and gold. In this way, a copper wiring can be formed as being adhered to a film of PET and the like. When a highly reactive metal such as copper is employed, it may exist intermediately as a compound of the relevant metal in the complex as long as it becomes the metal itself finally. In case for example of copper, copper oxide, instead of the metal oxide, may exist at the time when the complex is formed as a wiring pattern etc which is adhering strongly on the substrate according to the present invention. Subsequently, this copper oxide can be converted into the metal copper having a low resistance by allowing an excessive current to run or by external heating. Although the case only of using Cu.sup.2+ as a copper ion was exemplified above, Cu.sup.+ may also be used actually instead of Cu.sup.2+ to make a conductive polymer-metal complex dispersion liquid similarly.
Example 3
(149) In this Example, an experiment employing a dispersion liquid of a polypyrrole-silver complex was performed to show that the conductive polymer-metal complex dispersion liquid is preferable for filling a narrow hole such as via.
(150) Similarly to the dispersion liquid which has already been described, 2.5 cc of the acetonitrile solution containing silver nitrate at a concentration of 1 mol/L and pyrrole at a concentration of 0.2 mol/L was subjected to ultraviolet light irradiation to prepare a polypyrrole-silver complex dispersion liquid. This dispersion liquid had a blue color as described above. This dispersion liquid was used to subject a silicon substrate having a narrow hole having a diameter of 30 m and a depth of 100 m, which reflected an almost cylindrical form having a high aspect ratio, to the two types of the filling processing described below. The same experiment was performed for holes having diameters of 20, 50 and 80 m (constant depth of 100 m), which exhibited the results similar to those obtained for a diameter of 30 m. First filling processing: An operation involving immersing the aforementioned silicon substrate in the dispersion liquid while stirring for 1 minute followed by allowing the silicon substrate to be taken out and then dried is repeated 5 times. Second filling processing: The aforementioned silicon substrate was immersed in the dispersion liquid for 5 minutes with an ultrasonic irradiation in an ultrasonic washing machine and then taken out and dried.
(151) In any of the filling processings, any particular processing for improving the penetration of the dispersion liquid into the hole, such as reducing the pressure, was not performed, and merely immersion and stirring were performed.
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(154) This SEM image is not sufficient to ensure that the hole in the center of
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(159) Because of the nature of the BSE images, a site in which silver having a high atomic density appears bright when compared with the circumference. The Region E in
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(164) In still another example shown in
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INDUSTRIAL APPLICABILITY
(170) As described above, since the present invention allows a highly adhesive conductive polymer-metal complex thin layer to be formed readily and precisely to a wide range of the substrates, a substantial industrial utility can be expected.
(171) Also according to the present invention, since the adhesion effect based on that a microparticle of the conductive polymer-metal complex enters into and mates with a narrow hall on the surface of the various substrates such as PTFE allows this complex to be adhered readily and strongly onto the substrate, a substantial industrial utility can be expected.
(172) Also according to the present invention, an extremely simple processing which is sufficient to fill the conductive material into a narrow hole such as a via also provides a high industrial utility.
CITATION LIST
Patent Literatures
(173) Patent Literature 1: JP 2010-225697 A Patent Literature 2: Japanese Patent No. 3,743,801 Patent Literature 3: JP 2004-87427 A Patent Literature 4: JP 2007-229733 A
Non Patent Literatures
(174) Non Patent Literature 1: T. Yoshinaga et al., Trend of TSV technology research and development for three dimensional LSI packaging, Science & Technology Trends April 2010, pp. 23-34 Non Patent Literature 2: Non-electrolytic copper plating bath suitable for build-up method S. Hashimoto et al, Fine Plating, No. 55, Page 51-58 (September, 1999) Non Patent Literature 3: Simulation of coverage on size exhibiting non-linear surface reaction, H. Kim et al, Report of Functional substance institute of Kyushu University, Vol. 12, No. 1, (1998), Page 15-19 Non Patent Literature 4: S. Fujii et al., J. Mater. Chem., 178 (2007) 3777. Non Patent Literature 5: Yeon Jae Jung et al., Synth. Met., 161 (2011) 1991. Non Patent Literature 6: Mitsubishi Chemical's resistivity meter series Lineup catalogue http://www.dins.jp/dins_j/6data/pdf/catalog/Lineup_catalog_J0408-LP.3000US.pdf Non Patent Literature 7: Ultramicrographic inkjet device http://www.sijtechnology.com/jp/super_fine_inkjet/index.html Non Patent Literature 8: minute droplet application system http://www.applied-micro-systems.net/b300.html