Forming a transparent metal oxide layer on a conductive surface of a dielectric substrate

Abstract

A method and apparatus of forming a transparent metal oxide layer on a conductive surface of a dielectric substrate involves exposing first and second conductive surface portions of the conductive surface of the dielectric substrate to first and second electrolytes respectively to form first and second electrochemical cells in which the first conductive surface is part of the first electrochemical cell and the second conductive surface is part of the second electrochemical cell and wherein the electrochemical cells are electrically connected together by the conductive surface of the dielectric substrate. An electric potential applied across first and second counter electrodes in the first and second cells respectively drives an electric current through the first and second electrolytes and causes metal ions and oxygen in the second electrolyte to form the transparent metal oxide layer on the second conductive surface portion when a current is passed through the first and second electrolytes. The transparent metal oxide layer may be made non-conductive or conductive or even semi-conductive through the absence or inclusion of dopant in the second electrolyte. A conductive surface of a dielectric substrate of any length can be uniformly plated with a transparent metal oxide layer by moving the dielectric substrate relative to the first and second electrolytes while exposing the first and second surface portions to the first and second electrolytes respectively.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
         1 . A method of forming a transparent metal oxide layer on a conductive surface of a dielectric substrate, the method comprising:
 exposing first and second conductive surface portions of the conductive surface of the dielectric substrate to first and second electrolytes respectively;   forming a first electrochemical cell comprised of the first conductive surface portion in contact with said first electrolyte and a first electrode in contact with said first electrolyte and spaced apart from the first conductive surface portion;   forming a second electrochemical cell comprised of the second conductive surface portion in contact with said second electrolyte and a second electrode in contact with said second electrolyte and spaced apart from the second conductive surface portion;   wherein said first and second electrochemical cells are electrically connected together in series by the conductive surface; and   wherein said first electrolyte has first chemicals that facilitate conduction of electric current through said first electrolyte without facilitating significant electrochemical reaction at said first electrode or at the first conductive surface portion; and   wherein said second electrolyte has second chemicals that facilitate conduction of electric current through said second electrolyte, said second chemicals including a non-aqueous solvent, metal ions in a metal ion concentration at least sufficient to facilitate formation of the transparent metal oxide layer to a desired thickness and a source of oxygen suitable to facilitate formation of the transparent metal-oxide layer on the second conductive surface portion;   applying an electric potential between said first and second electrodes such that said second electrode has a positive polarity relative to said first electrode to cause an electric current to flow between said second electrode and said first electrode in series through said second electrolyte, the second conductive surface portion, the first conductive surface portion and said first electrolyte;   such that said second electrode is at a sufficiently more positive potential than the second conductive surface portion to cause an electrochemical reaction to occur at the second conductive surface portion to form said transparent metal oxide layer on the second conductive surface portion.   
     
     
         2 . The method of  claim 1  wherein said non-aqueous solvent is protic or aprotic. 
     
     
         3 . The method of  claim 1  or  2  further comprising releasing metal ions capable of forming the transparent metal oxide layer to be optically transparent in the visible region of the electromagnetic spectrum, from salts soluble in said non-aqueous solvent. 
     
     
         4 . The method of any one of  claims 1 - 3  further comprising causing said second electrolyte to include a dopant electrochemically embeddable into the transparent metal oxide layer to produce a conductive transparent metal oxide layer. 
     
     
         5 . The method of  claim 4  further comprising admitting a chemical supplement into at least one of said first and second electrolytes. 
     
     
         6 . The method of any one of  claims 1 - 5  further comprising counting coulombs of charges in said electric current and ceasing the application of said electric potential when a coulomb charge count meets a charge count criterion associated with a desired thickness of said transparent metal oxide layer. 
     
     
         7 . The method of any one of  claims 1 - 6  further comprising interrupting said current when said metal ion concentration in said second electrolyte meets a metal ion concentration criterion, replacing said second electrolyte, and re-establishing said electric current. 
     
     
         8 . The method of any one of  claims 1 - 7  further comprising moving said substrate relative to said first and second electrolytes in a direction from said first electrolyte to said second electrolyte while said electric current is flowing, to cause said transparent metal oxide layer to be formed in a lengthwise direction along the conductive surface of the substrate. 
     
     
         9 . The method of any one of  claims 1 - 7  wherein forming said first and second electrochemical cells comprises holding said first electrolyte in a first open-faced container and holding said second electrolyte in a second open-faced container. 
     
     
         10 . The method of  claim 9  further comprising defining said first and second open-faced containers by an entrance wall, an interior wall, an exit wall, first end wall portions and a first bottom wall portion, such that said first open-faced container is defined between said entrance wall, said interior wall, said first end wall portions and said first bottom wall portion and such that said second open-faced container is defined between said interior wall, said exit wall, second end wall portions and a second bottom wall portion. 
     
     
         11 . The method of  claim 10  further comprising causing said first electrode to extend through said entrance wall, a first end wall portion or said first bottom wall portion, at a first position in parallel spaced apart relation to said substrate and causing said second electrode to extend through said exit wall, a second end wall portion or said second bottom wall portion, at a second position in parallel spaced apart relation to said substrate. 
     
     
         12 . The method of any one of  claims 9 - 11  further comprising admitting the dielectric substrate having the conductive surface through an entrance opening in said entrance wall and causing said substrate to extend over said first and second open-faced containers such that said conductive surface faces said first and second open-faced containers, wherein said first conductive surface portion is a portion of the conductive surface that extends over said first container and wherein said second conductive surface portion is a portion of said conductive surface that extends over said second open-faced container and wherein the method further comprises causing a portion of said substrate to extend through an exit opening in an exit wall of said second open-faced container. 
     
     
         13 . The method of  claim 12  further comprising causing said entrance opening, and said exit opening to be sealed against the conductive layer on said dielectric substrate to prevent leakage of said first and second electrolytes respectively from said entrance and exit openings respectively. 
     
     
         14 . The method of  claim 13  further comprising causing said interior wall to be sealed against the conductive surface on said dielectric substrate to prevent exchange of said first and second electrolytes at said interior wall. 
     
     
         15 . The method of any one of  claims 9 - 14  further comprising moving said substrate relative to said first and second electrolytes in a direction from said first electrolyte to said second electrolyte while said electric current is flowing, to cause said transparent metal oxide layer to be formed in a lengthwise direction along the conductive surface of the substrate. 
     
     
         16 . The method of  claim 15  wherein moving comprises moving said substrate while holding said first and second open-faced containers stationary. 
     
     
         17 . The method of any one of  claims 9 - 11  further comprising causing the first and second open-faced containers to be placed open-face down on the conductive surface of the dielectric substrate such that the substrate extends under said entrance wall, said interior wall, said exit wall, and said first and second end wall portions such that the first and second conductive surfaces of the dielectric substrate face said first and second open-faced containers, wherein said first conductive surface portion is a portion of the conductive surface that extends under said first open-faced container and wherein the second conductive surface portion is a portion of said conductive surface that extends under said second open-faced container and wherein the method further comprises causing a portion of said conductive surface of the dielectric substrate to extend under said exit wall of said second open-faced container. 
     
     
         18 . The method of  claim 17  further comprising holding said dielectric substrate with the conductive surface face-up in a container holding an initial electrolyte and wherein causing the first and second open-faced containers to be placed open-face down on the conductive surface of the dielectric substrate comprises causing the first and second open-faced containers to be substantially submerged in said initial electrolyte and causing said entrance wall, said exit wall, and said first and second end wall portions to be sealed against said substrate to contain a first volume of said initial electrolyte in said first open-faced container and to contain a second volume of said initial electrolyte in said second open-faced container. 
     
     
         19 . The method of  claim 18  further comprising causing said interior wall to be sealed against the conductive surface of said dielectric substrate to prevent leakage of said first and second electrolytes respectively under said interior wall. 
     
     
         20 . The method of any one of  claims 9 - 12  and  17 - 19  further comprising moving said substrate relative to said first and second electrolytes in a direction from said first electrolyte to said second electrolyte while said electric current is flowing, to cause said transparent metal oxide layer to be formed in a lengthwise direction along the conductive surface of the substrate. 
     
     
         21 . The method of  claim 20  wherein moving comprises moving said first and second open-faced containers while holding said substrate stationary. 
     
     
         22 . A method of forming a transparent metal oxide layer on a first conductive surface of a first dielectric substrate, the method comprising:
 pressing a first conductive surface of the first dielectric substrate surface of a second dielectric substrate such that the frame defines a sealed space between the first conductive surface and the second conductive surface;   admitting an electrolyte having chemicals that facilitate conduction of electric current through said electrolyte into the sealed space through an opening in said frame gasket, said chemicals including a non-aqueous solvent, metal ions in a metal ion concentration at least sufficient to facilitate formation of the transparent metal oxide layer to a desired thickness and a source of oxygen suitable to facilitate formation of the transparent metal-oxide layer on the first conductive surface; and   applying an electric potential between said first and second conductive surfaces such that said first conductive surface has a negative polarity relative to said second conductive surface to cause an electric current to flow between said second conductive surface and said first conductive surface through said electrolyte to cause an electrochemical reaction to occur at the first conductive surface to form said transparent metal oxide layer on the first conductive surface.   
     
     
         23 . The method of  claim 22  wherein said non-aqueous solvent is protic or aprotic. 
     
     
         24 . The method of  claim 22  or  23  further comprising releasing metal ions capable of forming the transparent metal oxide layer to be optically transparent in the visible region of the electromagnetic spectrum, from salts soluble in said non-aqueous solvent. 
     
     
         25 . The method of any one of  claims 22 - 24  further comprising causing said second electrolyte to include a dopant electrochemically embeddable into the transparent metal oxide layer to produce a conductive transparent metal oxide layer. 
     
     
         26 . The method of  claim 25  further comprising admitting a chemical supplement into said electrolyte 
     
     
         27 . The method of any one of  claims 22 - 26  further comprising counting coulombs of charges in said electric current and ceasing the application of said electric potential when a coulomb charge count meets a coulomb charge count criterion associated with a desired thickness of said transparent metal oxide layer. 
     
     
         28 . The method of any one of  claim 22 - 26  further comprising interrupting said current when a metal ion concentration in said electrolyte meets a metal ion concentration criterion, replacing said electrolyte, and re-establishing said electric current. 
     
     
         29 . The method of any one of  claims 22 - 28  wherein said pressing comprises pressing sufficiently to compress said space-defining frame gasket to sufficiently seal said sealed space to prevent leakage of said electrolyte from said sealed space. 
     
     
         30 . The method of any one of  claims 22 - 29  wherein said applying an electric potential comprises fastening first and second conductive clamps on first and second opposite edges respectively of said first substrate to make electrical contact with said first conductive surface at opposite edges of said first substrate and fastening third and fourth of conductive clamps on third and fourth edges of said dielectric substrate to make electrical contact with said second conductive surface on said dielectric substrate and connecting said first and second clamps to a positive terminal of a current source and connecting said third and fourth clamps to a negative terminal of the current source. 
     
     
         31 . An apparatus for forming a transparent metal oxide layer on a conductive surface of a dielectric substrate, the apparatus comprising:
 means for holding a first electrolyte and a first electrode in contact with said first electrolyte;   means for holding a second electrolyte and a second electrode in contact with said second electrolyte;   means for simultaneously exposing first and second conductive surface portions of the conductive surface of the dielectric substrate to said first and second electrolytes respectively, such that the first and second conductive surface portions are spaced apart from the first and second electrodes respectively to form first and second electrochemical cells respectively and whereby said first and second electrochemical cells are electrically connected together in series by the conductive surface of the dielectric substrate;   wherein said first electrolyte has first chemicals that facilitate conduction of electric current through said first electrolyte without facilitating significant electrochemical reaction at said first electrode or at the first conductive surface portion; and   wherein said second electrolyte has second chemicals that facilitate conduction of electric current through said second electrolyte, said second chemicals including a non-aqueous solvent, metal ions in a metal ion concentration at least sufficient to facilitate formation of the transparent metal oxide layer to a desired thickness and a source of oxygen suitable to facilitate formation of the transparent metal-oxide layer on the second conductive surface portion;   means for applying an electric potential between said first and second electrodes such that said second electrode has a positive polarity relative to said first electrode to cause an electric current to flow between said second electrode and said first electrode in series through said second electrolyte, the second conductive surface portion, the first conductive surface portion and said first electrolyte;   such that said second electrode is at a sufficiently more positive potential than the second conductive surface portion to cause an electrochemical reaction to occur at the second conductive surface portion to form said transparent metal oxide layer on the second conductive surface portion.   
     
     
         32 . The apparatus of  claim 31  wherein said non-aqueous solvent is protic or aprotic solvent. 
     
     
         33 . The apparatus of  claim 31  or  32  further comprising releasing metal ions capable of forming the transparent metal oxide layer to be optically transparent in the visible region of the electromagnetic spectrum, from salts soluble said in non-aqueous solvent. 
     
     
         34 . The apparatus of any one of  claims 31 - 33  further comprising causing said second electrolyte to include a dopant electrochemically embeddable into the transparent metal oxide layer to produce a conductive transparent metal oxide layer. 
     
     
         35 . The apparatus of any one of  claims 31 - 34  further comprising means for counting coulombs of charges in said electric current and means, in communication with said means for counting coulombs, for ceasing the application of said electric potential when a coulomb charge count indicated by said means for counting coulombs meets a coulombs count criterion associated with a desired thickness of said transparent metal oxide layer. 
     
     
         36 . The apparatus of any one of  claim 31 - 35  further comprising means for interrupting said current when a metal ion concentration in said second electrolyte meets a metal ion concentration criterion, means for replacing said second electrolyte, and means for re-establishing said electric current after second electrolyte has been replaced. 
     
     
         37 . The apparatus of any one of  claims 31 - 36  further comprising means for moving said substrate relative to said first and second electrolytes in a direction from said first electrolyte to said second electrolyte while said electric current is flowing, to cause said transparent metal oxide layer to be formed in a lengthwise direction along the conductive surface of the substrate. 
     
     
         38 . The apparatus of any one of  claims 31 - 36  wherein said means for holding said first electrolyte and said first electrode comprises a first open-faced container and wherein said means for holding said second electrolyte and said second electrode comprises a second open-faced container. 
     
     
         39 . The apparatus of  claim 38  wherein said first open-faced container comprises an entrance wall and an interior wall, a pair of first end walls and a first bottom wall portion and wherein said second open-faced container comprises said interior wall and an exit wall and a pair of second end walls and a second bottom wall portion wherein said first and second open-faced containers have first and second end wall portions. 
     
     
         40 . The apparatus of  claim 39  wherein said first electrode extends through said entrance wall, at least one of said first end wall portions or said first bottom wall portion, at a first position in parallel spaced apart relation to said substrate and wherein said second electrode extends through said exit wall, at least one of said second end wall portions or said second bottom wall portion, at a second position in parallel spaced apart relation to said conductive surface of the dielectric substrate. 
     
     
         41 . The apparatus of any one of  claim 39  or  40  wherein said means for simultaneously exposing the first and second surface portions of the conductive surface of the substrate comprises an entrance opening in said entrance wall and an exit opening in said exit wall, for receiving and positioning said dielectric substrate to cause said dielectric substrate to extend over said first and second open-faced containers such that said first conductive surface portion faces said first open-faced container and such that said second conductive surface portion faces said second open-faced container. 
     
     
         42 . The apparatus of  claim 41  further comprising entrance and exit seals operably configured to seal said entrance opening and said exit opening against the conductive surface of said dielectric substrate to prevent leakage of said first and second electrolytes respectively from said entrance and exit openings respectively. 
     
     
         43 . The apparatus of  claim 42  further comprising an interior wall seal operably configured to seal said interior wall against the conductive surface of said dielectric substrate to prevent exchange of said first and second electrolytes at said interior wall. 
     
     
         44 . The apparatus of any one of  claims 38 - 43  further comprising means for moving said substrate relative to said first and second electrolytes in a direction from said first electrolyte to said second electrolyte while said electric current is flowing, to cause said transparent metal oxide layer to be formed in a lengthwise direction along the conductive surface of the substrate. 
     
     
         45 . The apparatus of  claim 44  wherein said means for moving comprises means for moving said substrate and means for holding said first and second open-faced containers stationary while said substrate is being moved. 
     
     
         46 . The apparatus of any one of  claims 39 - 40  further comprising means for positioning said first and second open-faced containers face down on the conductive surface of the dielectric substrate such that the substrate extends under said entrance wall, said interior wall, said exit wall, and said first and second pairs of end walls such that the first and second conductive surfaces of the dielectric substrate face said first and second open-faced containers. 
     
     
         47 . The apparatus of  claim 46  further comprising:
 means for holding a volume of an initial electrolyte; 
 means for holding said dielectric substrate with the conductive surface face-up in said initial electrolyte; and 
 wherein said means for positioning said first and second open-faced containers face down on the conductive surface of the dielectric substrate comprises means for causing the first and second open-faced containers to be substantially submerged in said initial electrolyte; and 
 means for sealing said entrance wall, said exit wall, and said first and second end wall portions against said substrate to contain a first volume of said initial electrolyte in said first open-faced container and to contain a second volume of said initial electrolyte in said second open-faced container. 
 
     
     
         48 . The apparatus of  claim 47  further comprising means for sealing said interior wall against the conductive surface of said dielectric substrate to prevent leakage of said first and second electrolytes respectively at said interior wall. 
     
     
         49 . The apparatus of any one of  claims 45 - 47  further comprising means for moving said substrate relative to said first and second electrolytes in a direction from said first electrolyte to said second electrolyte while said electric current is flowing, to cause said transparent metal oxide layer to be formed in a lengthwise direction along the conductive surface of the substrate. 
     
     
         50 . The apparatus of  claim 49  wherein said means for moving comprises means for moving said first and second open-faced containers and means for holding said substrate stationary while said first and second open-faced containers are being moved. 
     
     
         51 . An apparatus for forming a transparent metal oxide layer on a first conductive surface of a first dielectric substrate, the apparatus comprising:
 a space-defining frame gasket positioned on the first conductive surface of the first dielectric substrate, the gasket having an inner wall defining a space bounded by said inner wall and a portion of the first conductive surface of the first dielectric substrate;   a second substrate having a second conductive surface;   means for pressing the first conductive surface of the first substrate against the space-defining frame gasket to cause said space to be a sealed space;   an opening in said frame gasket for admitting into the sealed space an electrolyte having chemicals that facilitate conduction of electric current through said electrolyte, said chemicals including non-aqueous solvent, metal ions and a source of oxygen suitable to facilitate formation of the transparent metal-oxide layer on the first conductive surface; and   means for applying an electric potential between said second conductive surface of said second dielectric substrate and said first conductive surface of said first substrate such that said first conductive surface of said first substrate has a negative polarity relative to said second conductive surface of said second dielectric conductive surface and said first conductive surface, through said electrolyte to cause an electrochemical reaction to occur at the first conductive surface to form said transparent metal oxide layer on the first conductive surface.   
     
     
         52 . The apparatus of  claim 51  wherein said non-aqueous solvent is protic or aprotic solvent. 
     
     
         53 . The apparatus of  claim 51  or  52  further comprising releasing metal ions capable of forming the transparent metal oxide layer to be optically transparent in the visible region of the electromagnetic spectrum, from salts soluble in said non-aqueous solvent. 
     
     
         54 . The apparatus of any one of  claims 51 - 53  further comprising causing said second electrolyte to include a dopant electrochemically embeddable into the transparent metal oxide layer to produce a conductive transparent metal oxide layer. 
     
     
         55 . The apparatus of  claim 53  or  54  further comprising means for counting coulombs of charges in said electric current and means in communication with said means for counting coulombs for ceasing the application of said electric potential when a coulomb charge count indicated by said means for counting coulombs meets a coulomb count criterion associated with a desired thickness of said transparent metal oxide layer. 
     
     
         56 . The apparatus of any one of  claim 52 - 55  further comprising means for interrupting said current when a metal ion concentration in said electrolyte meets a metal ion concentration criterion, means for replacing said electrolyte, and means for re-establishing said electric current after said electrolyte has been replaced. 
     
     
         57 . The apparatus of any one of  claims 52 - 56  wherein said means for pressing is operably configured to compress said space-defining frame gasket to sufficiently seal said sealed space to prevent leakage of said electrolyte from said sealed space. 
     
     
         58 . The apparatus of any one of  claims 51 - 57  wherein said means for applying an electric potential comprises first and second conductive clamps on first and second opposite edges respectively of said first substrate in electrical contact with said first conductive coating at opposite side edges of said first substrate and third and fourth conductive clamps on third and fourth opposite edges of said dielectric substrate in electrical contact with said second conductive surface of opposite side edges of said dielectric substrate, wherein said first and second clamps are operably configured to be connected to a negative terminal of a current source and wherein said third and fourth clamps are operably configured to be connected to a positive terminal of the current source.