WO2013092312A1 - Deposition of copper-tin-zinc alloys from an electrolyte - Google Patents
Deposition of copper-tin-zinc alloys from an electrolyte Download PDFInfo
- Publication number
- WO2013092312A1 WO2013092312A1 PCT/EP2012/075111 EP2012075111W WO2013092312A1 WO 2013092312 A1 WO2013092312 A1 WO 2013092312A1 EP 2012075111 W EP2012075111 W EP 2012075111W WO 2013092312 A1 WO2013092312 A1 WO 2013092312A1
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- WO
- WIPO (PCT)
- Prior art keywords
- electrolyte
- copper
- zinc
- tin
- range
- Prior art date
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- 239000003792 electrolyte Substances 0.000 title claims abstract description 80
- 230000008021 deposition Effects 0.000 title claims abstract description 27
- PDYXSJSAMVACOH-UHFFFAOYSA-N [Cu].[Zn].[Sn] Chemical group [Cu].[Zn].[Sn] PDYXSJSAMVACOH-UHFFFAOYSA-N 0.000 title claims description 11
- 229910001297 Zn alloy Inorganic materials 0.000 title claims description 10
- 239000010949 copper Substances 0.000 claims abstract description 64
- 239000011701 zinc Substances 0.000 claims abstract description 50
- 229910052802 copper Inorganic materials 0.000 claims abstract description 44
- 239000011135 tin Substances 0.000 claims abstract description 41
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 40
- 235000011180 diphosphates Nutrition 0.000 claims abstract description 35
- 238000000034 method Methods 0.000 claims abstract description 31
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 25
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 claims abstract description 22
- 229910052718 tin Inorganic materials 0.000 claims abstract description 22
- 229910052725 zinc Inorganic materials 0.000 claims abstract description 21
- -1 zinc (II) ions Chemical class 0.000 claims abstract description 21
- PTFCDOFLOPIGGS-UHFFFAOYSA-N Zinc dication Chemical compound [Zn+2] PTFCDOFLOPIGGS-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229940071182 stannate Drugs 0.000 claims abstract description 12
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical compound [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 claims abstract description 6
- 229910001431 copper ion Inorganic materials 0.000 claims abstract description 6
- XPPKVPWEQAFLFU-UHFFFAOYSA-J diphosphate(4-) Chemical compound [O-]P([O-])(=O)OP([O-])([O-])=O XPPKVPWEQAFLFU-UHFFFAOYSA-J 0.000 claims abstract 2
- 229910045601 alloy Inorganic materials 0.000 claims description 24
- 239000000956 alloy Substances 0.000 claims description 24
- 229910052751 metal Inorganic materials 0.000 claims description 22
- 239000002184 metal Substances 0.000 claims description 22
- 125000005402 stannate group Chemical group 0.000 claims description 15
- 150000001875 compounds Chemical class 0.000 claims description 11
- 150000002500 ions Chemical class 0.000 claims description 11
- 239000000463 material Substances 0.000 claims description 9
- 150000002739 metals Chemical class 0.000 claims description 8
- 239000005864 Sulphur Substances 0.000 claims description 7
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 5
- 239000002253 acid Substances 0.000 claims description 4
- 150000003467 sulfuric acid derivatives Chemical class 0.000 claims description 4
- 229910000597 tin-copper alloy Inorganic materials 0.000 claims description 4
- 229910007610 Zn—Sn Inorganic materials 0.000 claims description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-N carbonic acid Chemical class OC(O)=O BVKZGUZCCUSVTD-UHFFFAOYSA-N 0.000 claims description 3
- 238000006243 chemical reaction Methods 0.000 claims description 3
- TVZPLCNGKSPOJA-UHFFFAOYSA-N copper zinc Chemical compound [Cu].[Zn] TVZPLCNGKSPOJA-UHFFFAOYSA-N 0.000 claims description 3
- 239000000758 substrate Substances 0.000 claims description 3
- 239000010409 thin film Substances 0.000 claims description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 3
- 229910000881 Cu alloy Inorganic materials 0.000 claims description 2
- 229910019142 PO4 Inorganic materials 0.000 claims description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 2
- LSNNMFCWUKXFEE-UHFFFAOYSA-N Sulfurous acid Chemical class OS(O)=O LSNNMFCWUKXFEE-UHFFFAOYSA-N 0.000 claims description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 2
- 238000010521 absorption reaction Methods 0.000 claims description 2
- 150000007513 acids Chemical class 0.000 claims description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 claims description 2
- 150000001991 dicarboxylic acids Chemical class 0.000 claims description 2
- 150000004820 halides Chemical class 0.000 claims description 2
- 150000004679 hydroxides Chemical class 0.000 claims description 2
- 229910003455 mixed metal oxide Inorganic materials 0.000 claims description 2
- 150000002763 monocarboxylic acids Chemical class 0.000 claims description 2
- 150000002823 nitrates Chemical class 0.000 claims description 2
- 150000002826 nitrites Chemical class 0.000 claims description 2
- 235000021317 phosphate Nutrition 0.000 claims description 2
- 150000003013 phosphoric acid derivatives Chemical class 0.000 claims description 2
- 229910052698 phosphorus Inorganic materials 0.000 claims description 2
- 239000011574 phosphorus Substances 0.000 claims description 2
- 229940065287 selenium compound Drugs 0.000 claims description 2
- 150000003343 selenium compounds Chemical class 0.000 claims description 2
- 239000010936 titanium Substances 0.000 claims description 2
- 229910052719 titanium Inorganic materials 0.000 claims description 2
- 230000000087 stabilizing effect Effects 0.000 claims 1
- 229910002058 ternary alloy Inorganic materials 0.000 abstract description 13
- 229940048084 pyrophosphate Drugs 0.000 description 26
- 239000000203 mixture Substances 0.000 description 20
- XPPKVPWEQAFLFU-UHFFFAOYSA-N diphosphoric acid Chemical compound OP(O)(=O)OP(O)(O)=O XPPKVPWEQAFLFU-UHFFFAOYSA-N 0.000 description 19
- 238000004519 manufacturing process Methods 0.000 description 10
- GEHJYWRUCIMESM-UHFFFAOYSA-L sodium sulfite Chemical compound [Na+].[Na+].[O-]S([O-])=O GEHJYWRUCIMESM-UHFFFAOYSA-L 0.000 description 10
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 description 9
- 229910001128 Sn alloy Inorganic materials 0.000 description 8
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 8
- 229910021653 sulphate ion Inorganic materials 0.000 description 8
- 229910001369 Brass Inorganic materials 0.000 description 6
- VMQMZMRVKUZKQL-UHFFFAOYSA-N Cu+ Chemical class [Cu+] VMQMZMRVKUZKQL-UHFFFAOYSA-N 0.000 description 6
- 239000010951 brass Substances 0.000 description 6
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 6
- 239000011734 sodium Substances 0.000 description 6
- 229910000906 Bronze Inorganic materials 0.000 description 5
- 239000000654 additive Substances 0.000 description 5
- 239000010974 bronze Substances 0.000 description 5
- QCPTVXCMROGZOL-UHFFFAOYSA-L dipotassium;oxalate;hydrate Chemical compound O.[K+].[K+].[O-]C(=O)C([O-])=O QCPTVXCMROGZOL-UHFFFAOYSA-L 0.000 description 5
- 238000005868 electrolysis reaction Methods 0.000 description 5
- 235000010265 sodium sulphite Nutrition 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- ZPWVASYFFYYZEW-UHFFFAOYSA-L dipotassium hydrogen phosphate Chemical compound [K+].[K+].OP([O-])([O-])=O ZPWVASYFFYYZEW-UHFFFAOYSA-L 0.000 description 4
- 239000010408 film Substances 0.000 description 4
- 239000007787 solid Substances 0.000 description 4
- RYCLIXPGLDDLTM-UHFFFAOYSA-J tetrapotassium;phosphonato phosphate Chemical compound [K+].[K+].[K+].[K+].[O-]P([O-])(=O)OP([O-])([O-])=O RYCLIXPGLDDLTM-UHFFFAOYSA-J 0.000 description 4
- BRLQWZUYTZBJKN-UHFFFAOYSA-N Epichlorohydrin Chemical compound ClCC1CO1 BRLQWZUYTZBJKN-UHFFFAOYSA-N 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- 150000001412 amines Chemical class 0.000 description 3
- 239000007795 chemical reaction product Substances 0.000 description 3
- 230000003647 oxidation Effects 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 2
- 229920000388 Polyphosphate Polymers 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 2
- 235000010299 hexamethylene tetramine Nutrition 0.000 description 2
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 description 2
- 125000001997 phenyl group Chemical class [H]C1=C([H])C([H])=C(*)C([H])=C1[H] 0.000 description 2
- 239000001205 polyphosphate Substances 0.000 description 2
- 235000011176 polyphosphates Nutrition 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000011669 selenium Substances 0.000 description 2
- 229910052711 selenium Inorganic materials 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical class [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 229910017518 Cu Zn Inorganic materials 0.000 description 1
- 229910017755 Cu-Sn Inorganic materials 0.000 description 1
- 229910017752 Cu-Zn Inorganic materials 0.000 description 1
- 229910002475 Cu2ZnSnS4 Inorganic materials 0.000 description 1
- 229910017927 Cu—Sn Inorganic materials 0.000 description 1
- 229910017943 Cu—Zn Inorganic materials 0.000 description 1
- XFXPMWWXUTWYJX-UHFFFAOYSA-N Cyanide Chemical compound N#[C-] XFXPMWWXUTWYJX-UHFFFAOYSA-N 0.000 description 1
- FEWJPZIEWOKRBE-JCYAYHJZSA-N Dextrotartaric acid Chemical compound OC(=O)[C@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-JCYAYHJZSA-N 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical class C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical class [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- ABLZXFCXXLZCGV-UHFFFAOYSA-N Phosphorous acid Chemical compound OP(O)=O ABLZXFCXXLZCGV-UHFFFAOYSA-N 0.000 description 1
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical class [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 1
- BUGBHKTXTAQXES-UHFFFAOYSA-N Selenium Chemical compound [Se] BUGBHKTXTAQXES-UHFFFAOYSA-N 0.000 description 1
- FEWJPZIEWOKRBE-UHFFFAOYSA-N Tartaric acid Natural products [H+].[H+].[O-]C(=O)C(O)C(O)C([O-])=O FEWJPZIEWOKRBE-UHFFFAOYSA-N 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229910000147 aluminium phosphate Inorganic materials 0.000 description 1
- 239000011575 calcium Chemical class 0.000 description 1
- 229910052791 calcium Chemical class 0.000 description 1
- 239000003093 cationic surfactant Substances 0.000 description 1
- 235000015165 citric acid Nutrition 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 150000001879 copper Chemical class 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- IOUCSUBTZWXKTA-UHFFFAOYSA-N dipotassium;dioxido(oxo)tin Chemical compound [K+].[K+].[O-][Sn]([O-])=O IOUCSUBTZWXKTA-UHFFFAOYSA-N 0.000 description 1
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 description 1
- TVQLLNFANZSCGY-UHFFFAOYSA-N disodium;dioxido(oxo)tin Chemical compound [Na+].[Na+].[O-][Sn]([O-])=O TVQLLNFANZSCGY-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000004312 hexamethylene tetramine Substances 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000011777 magnesium Chemical class 0.000 description 1
- 229910052749 magnesium Inorganic materials 0.000 description 1
- 229960004011 methenamine Drugs 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 150000007524 organic acids Chemical class 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 238000007747 plating Methods 0.000 description 1
- 239000011591 potassium Chemical class 0.000 description 1
- 229910052700 potassium Inorganic materials 0.000 description 1
- 229940005657 pyrophosphoric acid Drugs 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 235000002639 sodium chloride Nutrition 0.000 description 1
- 239000001488 sodium phosphate Substances 0.000 description 1
- 229910000162 sodium phosphate Inorganic materials 0.000 description 1
- 229940079864 sodium stannate Drugs 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 239000011975 tartaric acid Substances 0.000 description 1
- 235000002906 tartaric acid Nutrition 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical compound [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/56—Electroplating: Baths therefor from solutions of alloys
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/56—Electroplating: Baths therefor from solutions of alloys
- C25D3/58—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of copper
-
- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
- C25D3/00—Electroplating: Baths therefor
- C25D3/02—Electroplating: Baths therefor from solutions
- C25D3/56—Electroplating: Baths therefor from solutions of alloys
- C25D3/60—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of tin
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L31/0248—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies
- H01L31/0256—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by their semiconductor bodies characterised by the material
- H01L31/0264—Inorganic materials
- H01L31/032—Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312
- H01L31/0326—Inorganic materials including, apart from doping materials or other impurities, only compounds not provided for in groups H01L31/0272 - H01L31/0312 comprising AIBIICIVDVI kesterite compounds, e.g. Cu2ZnSnSe4, Cu2ZnSnS4
Definitions
- the present invention relates to a cyanide-free, pyrophosphate-containing electrolyte and a process for the electrolytic deposition of a ternary alloy of the elements copper, tin and zinc.
- the electrolyte and the process are characterized in that not only zinc (II) ions and stannate anions but also copper ions are present in the electrolyte used.
- the copper and zinc ions are present in a particular molar ratio relative to one another and to the pyrophosphate anions.
- the solderability of the resulting layer and possibly its mechanical strength are the critical properties of the layer to be produced.
- the appearance of the layers is generally less important than their functionality for use in this field.
- the decorative effect and also durability of the layer with an ideally unchanged appearance are the important target parameters in the production of bronze or brass layers on consumer goods.
- Cyanide-free electrolytic baths for the deposition of brass layers may be found, for example, in EP 790332. There, not only the copper and zinc, which can be added as pyrophosphate salts to the electrolyte, but also metal polyphosphates are added to the electrolyte. Possible metal polyphosphates are pyrophosphate salts of sodium, potassium, magnesium or calcium. The deposition of copper-zinc-tin layers is not described here.
- EP 1 146148 describes a cyanide-free copper-tin electrolyte which contains the reaction product of an amine and an epichlorohydrin in a molar ratio of 1 :1 and also a cationic surfactant.
- the amine can be hexamethylene tetramine.
- JP 10102278 and US 6416571 describe baths for the deposition of copper-tin alloys.
- Cyanide-free electrolytic baths for the deposition of bronze layers are likewise adequately known.
- WO 2009109271 reports that copper and tin can be deposited together from appropriate baths which have a large excess of pyrophosphate ions. All these teachings disclose exclusively the deposition of bronzes, i.e. copper-tin alloys.
- a ternary alloy consisting of copper, tin and zinc from a cyanide-free electrolyte is disclosed, for example, in EP 21 16634.
- a high concentration of pyrophosphate anions in the electrolyte but also a specific reaction product of hexamethylene tetramines and epichlorohydrin at a virtually neutral pH of the electrolyte are used.
- US20010014407 mentions in passing the deposition of a ternary alloy of Cu/Sn/Zn on copper surfaces as corrosion protection. Relatively low-tin alloys are obtained from the pyrophosphate-containing electrolyte.
- US20100147696 discloses the deposition of Cu-Zn-Sn alloy from electrolytes containing phosphonic acid. The deposition processes described here give white coatings which are, however, relatively low in zinc.
- a cyanide-free, pyrophosphate-containing electrolyte for the deposition of ternary copper-zinc-tin alloys is described in Thin Solid Films, 517 (2009) 251 1 -2514.
- a layer which is not defined in more detail is deposited from an alkaline electrolyte containing the metals copper in the oxidation state +2, zinc in the oxidation state +2 and tin in the oxidation state +4.
- the electrolyte described here is said to contain a tenfold excess of tin and lead only to low-copper deposits.
- EP 2037006 describes the electrolytic deposition of copper-tin-zinc alloys in a very particular atom ratio.
- the layers deposited have a composition which is said to be close to the formula Cu2ZnSn.
- the layers obtained in this way serve as base layer for the production of kesterite (CZTS or Cu2ZnSn(S,Se)4) which is a promising material for the production of photovoltaically active molecules (Solar Energy Materials & Solar Cells 201 1 , 95, 2136-2140; Chemical Physics Letters 201 1 , 501 , 619-622).
- a correspondingly produced Cu2ZnSn layer is subsequently converted by reaction with sulphur or sulphur-containing compounds at elevated temperatures into the corresponding kesterite phase (e.g.: Thin Solid Films 2009, 517, 2465-2468).
- sulphur or sulphur-containing compounds at elevated temperatures into the corresponding kesterite phase
- Such a procedure is likewise addressed in EP 2037006.
- the specific electrolytically produced Cu2ZnSn deposits are obtained from an electrolyte to which particular disubstituted benzene derivatives have been added.
- the copper and zinc ions can be added as pyrophosphates to the electrolyte.
- the tin is preferably used as stannate.
- the electrolytes described for the deposition of the ternary alloy of copper, tin and zinc all have only a low ability to deposit a desired ternary alloy composition of this type when, for example, specific additional additives are not added to the electrolyte or extremely high tin-IV concentrations are not present in the electrolyte.
- the electrolyte should ideally have a simple composition.
- the process and the electrolyte according to the invention should also be superior to the processes and electrolytes known from the prior art from ecological and economic points of view.
- an aqueous, cyanide-free, pyrophosphate-containing electrolyte containing the metals copper and zinc to be deposited in dissolved form and tin as dissolved stannate where the electrolyte has a molar ratio of pyrophosphate anions to total copper and zinc ions in the range from >1 :2 to 20:1 and the molar ratio of copper ions to zinc ions in the electrolyte is in the range from 3:1 to 1 :4, for the electrolytic deposition of a copper-tin-zinc alloy leads, extremely surprisingly but no less advantageously, to achievement of the stated object.
- an advantageous ternary alloy composition can be achieved using the electrolyte described here when the pyrophosphate ions are present in excess over the copper and zinc ions in the electrolyte, when at the same time a particular ratio of copper to zinc ions is set and at the same time Sn is present as Sn 4+ .
- the electrolyte described here is noteworthy for the fact that obviously no further substances which influence the deposition of the ternary alloy have to be added to the electrolyte in order to bring about an appropriately composed deposition of copper-zinc-tin.
- reaction products of amines with epichlorohydrin as proposed in EP 21 16634 (mentioned at the outset) and the addition of disubstituted benzene derivatives known from EP 2037006 can be dispensed with.
- the composition of the ternary alloy of copper, tin and zinc can obviously be controlled in a simple manner via the abovementioned features alone. This has not yet been proposed in the prior art.
- the cyanide-free electrolyte it is advantageous for the cyanide-free electrolyte to have a certain concentration of stabilizers.
- This task can be performed solely by the pyrophosphate anions present in the electrolyte.
- a person skilled in the art is free to add further stabilizers to the electrolyte.
- the concentration of pyrophosphate anions can be adjusted as desired within the abovementioned limits by a person skilled in the art and, as indicated above, dependent on the amount of copper and zinc ions used.
- a person skilled in the art will in this task be guided by, firstly, an optimal alloy composition being formed and, secondly, by the smallest possible amount of starting materials having to be employed for the deposition.
- the preferred range for the molar ratio of pyrophosphate anions to the sum of Cu and Zn ions addressed here should therefore be in the range from 1 :1.6 to 4:1. Particular preference is in this context given to a range from 1 :1 .4 to 2:1 .
- the metals copper and zinc are present in ionically dissolved form in the present electrolyte.
- the copper can be added in the form of copper (I) salts or in the form of divalent copper salts or mixtures thereof to the electrolyte.
- Zinc will be present in the form of 2-valent ions in the electrolyte.
- the molar ratio of copper ions to zinc ions is preferably in the range from 2:1 to 1 :3. Very particular preference is given to a value of about 1 :1 - 1 :2.
- the tin is added as stannate salt, i.e. in the 4-valent form, to the electrolyte. Such stannate salts are well known to those skilled in the art.
- Particularly suitable stannate salts here are, for example, sodium stannate and potassium stannate.
- the ratios of the concentrations of copper and zinc ions relative to one another and also of the sum of these two ions to pyrophosphate anions are critical in determining the composition of the alloy deposited. It is naturally also necessary for the tin used to be present in a particular ratio to the copper and zinc ions.
- the molar ratio of stannate salt used to the sum of copper and zinc ions should be 1 :1 - 6:1 , preferably 1 .5:1 - 4:1 and particularly preferably from 2:1 to 3:1.
- the concentration ranges of the metal in the electrolyte can be selected by a person skilled in the art. It has been found to be advantageous for the ion concentration of copper to be in the range from 0.1 to 10 g/l of electrolyte, the concentration of tin to be in the range from 0.5 to 20 g/l of electrolyte and the ion concentration of zinc to be in the range from 0.2 to 20 g/l of electrolyte.
- the concentration of copper is particularly preferably 0.3 - 5 g/l, very preferably 0.5 - 1 .0 g/l.
- the concentration of zinc is particularly preferably 0.3 - 10 g/l, very preferably 0.5 - 2.0 g/l.
- the concentration of tin is particularly preferably 2 - 15 g/l, very preferably 3.5 - 10 g/l.
- Copper is present in a concentration of 0.5 - 1 g/l
- Zinc is present in a concentration of 0.5 - 2 g/l
- Tin is present in a concentration of 3.5 - 7.5 g/l
- the copper and zinc ions are present in dissolved form in the electrolyte.
- compounds of these metals to be deposited which are soluble in water under the reaction conditions indicated, it is possible to employ compounds selected from the group consisting of pyrophosphates, carbonates, hydrogencarbonates, sulphites, sulphates, phosphates, nitrites, nitrates, halides, hydroxides, oxide- hydroxides, oxides and combinations thereof.
- the electrolyte is operated in the slightly acidic to strongly alkaline range.
- the pH of the electrolyte is preferably in the range from 6 to 13, more preferably from 7.5 to 12 and very particularly preferably from 8 to 1 1 .5.
- the pH of the electrolyte according to the invention is especially preferably about 1 1.
- Preferred buffer substances are salts of weak organic or inorganic acids selected from the group consisting of phosphoric acid and citric acid.
- additives selected from the group consisting of monocarboxylic and dicarboxylic acids, alkanesulphonic acids, betaines and aromatic nitro compounds can be added to the electrolyte.
- additives are adequately known for the present type of baths, in particular in the field of deposition of brass or bronze.
- Such additives are particularly preferably selected from the group consisting of oxalic acid, tartaric acid, citric acid and salts thereof.
- the present invention likewise provides a process for the electrolytic deposition of Cu- Zn-Sn alloy layers, in which the substrate to be coated is dipped as cathode into an electrolyte according to the invention and a flow of current is established between the anode and the cathode.
- the embodiments of the electrolyte mentioned as preferred are analogously likewise preferred for the process.
- the proportion of copper in the ternary alloy deposited is advantageous for the proportion of copper in the ternary alloy deposited to be in the range from 38 to 44% by weight, the proportion of tin to be in the range from 34 to 42% by weight and the proportion of zinc to be in the range from 16 to 26% by weight.
- alloys containing 39 - 42% by weight of Cu very preferably about 40 - 41 % by weight.
- the sum of the alloy constituents should be 100% by weight.
- the alloy deposited should have a thickness of 0.4 - 5 ⁇ , preferably 0.5 - 3 m and very particularly preferably 1 - 2 ⁇ . It may be pointed out that the alloy composition can likewise change with the temperature prevailing during the electrolysis.
- the electrolysis is therefore carried out in the range from 20 to 90°C, preferably from 30 to 60°C and very preferably about 45°C.
- the composition of the ternary alloy of copper, tin and zinc can likewise change with the current density set during the electrolysis. It is advantageous to set a current density in the range from 0.1 to 5 ampere per square decimetre.
- the current density is preferably from 0.2 to 1 .0 ampere per square decimetre, very preferably from 0.3 to 0.8 ampere per square decimetre.
- anode it is possible to use any electrode which comes into question for this purpose to a person skilled in the art. Preference is given to using insoluble anodes (e.g. platinated titanium anodes or mixed metal oxide anodes).
- insoluble anodes e.g. platinated titanium anodes or mixed metal oxide anodes.
- soluble anodes composed of a material selected from the group consisting of electrolytic copper, phosphorus-containing copper, tin, tin-copper alloy, zinc-copper alloy and zinc- tin-copper alloy or combinations of these anodes are likewise advantageous.
- the alloy composition achieved by means of electrolysis preferably very closely approximates that corresponding to the alloy base material in the material kesterite (Cu2ZnSnS4).
- the layer produced by the process of the invention very preferably consists of a composition close to the formula Cu2ZnSn. From this, the desired compound Cu2ZnSn(SeS)4 (CZTS) is produced by action of sulphur, selenium and/or appropriate compounds using appropriate processes as discussed in the literature.
- Electrolyte composition according to the invention (Cu:Zn
- Electrolyte composition according to the invention (Cu:Zn)
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Abstract
The present invention relates to a cyanide-free, pyrophosphate-containing electrolyte and a process for the electrolytic deposition of a ternary alloy of the elements copper, tin and zinc. The electrolyte and the process are characterized in that not only zinc (II) ions and copper ions but also stannate anions are present in the electrolyte used. The copper and zinc ions are present in a particular molar ratio relative to one another and to the pyrophosphate anions.
Description
Deposition of copper-tin-zinc alloys from an electrolyte
Description
The present invention relates to a cyanide-free, pyrophosphate-containing electrolyte and a process for the electrolytic deposition of a ternary alloy of the elements copper, tin and zinc. The electrolyte and the process are characterized in that not only zinc (II) ions and stannate anions but also copper ions are present in the electrolyte used. The copper and zinc ions are present in a particular molar ratio relative to one another and to the pyrophosphate anions.
The electrolytic deposition of brass (Cu-Zn alloy) and bronzes (Cu-Sn alloy) on consumer goods or decorative goods has been known for a long time. They serve, inter alia, as a replacement for nickel-containing finishing layers and are, for example, applied inexpensively to appropriate substrates in electrochemical barrel or rack plating processes.
In the production of brass and bronze layers for the electronics industry, the solderability of the resulting layer and possibly its mechanical strength are the critical properties of the layer to be produced. The appearance of the layers is generally less important than their functionality for use in this field. On the other hand, the decorative effect and also durability of the layer with an ideally unchanged appearance are the important target parameters in the production of bronze or brass layers on consumer goods.
In the production of brass or bronze layers, known processes are not only the conventional processes using cyanide-containing and thus highly toxic, alkaline baths but also various electrochemical processes which can mostly be assigned according to the composition of their electrolytes to one of two main groups found in the prior art: processes using electrolytes based on organosulphonic acid or processes using baths based on disphosphoric acid (pyrophosphoric acid).
Cyanide-free electrolytic baths for the deposition of brass layers may be found, for example, in EP 790332. There, not only the copper and zinc, which can be added as pyrophosphate salts to the electrolyte, but also metal polyphosphates are added to the electrolyte. Possible metal polyphosphates are pyrophosphate salts of sodium,
potassium, magnesium or calcium. The deposition of copper-zinc-tin layers is not described here.
EP 1 146148 describes a cyanide-free copper-tin electrolyte which contains the reaction product of an amine and an epichlorohydrin in a molar ratio of 1 :1 and also a cationic surfactant. The amine can be hexamethylene tetramine. JP 10102278 and US 6416571 describe baths for the deposition of copper-tin alloys. Cyanide-free electrolytic baths for the deposition of bronze layers are likewise adequately known. Thus, for example, WO 2009109271 reports that copper and tin can be deposited together from appropriate baths which have a large excess of pyrophosphate ions. All these teachings disclose exclusively the deposition of bronzes, i.e. copper-tin alloys.
The deposition of a ternary alloy consisting of copper, tin and zinc from a cyanide-free electrolyte is disclosed, for example, in EP 21 16634. There, not only a high concentration of pyrophosphate anions in the electrolyte but also a specific reaction product of hexamethylene tetramines and epichlorohydrin at a virtually neutral pH of the electrolyte are used. US20010014407 mentions in passing the deposition of a ternary alloy of Cu/Sn/Zn on copper surfaces as corrosion protection. Relatively low-tin alloys are obtained from the pyrophosphate-containing electrolyte.
US20100147696 discloses the deposition of Cu-Zn-Sn alloy from electrolytes containing phosphonic acid. The deposition processes described here give white coatings which are, however, relatively low in zinc.
A cyanide-free, pyrophosphate-containing electrolyte for the deposition of ternary copper-zinc-tin alloys is described in Thin Solid Films, 517 (2009) 251 1 -2514. Here, a layer which is not defined in more detail is deposited from an alkaline electrolyte containing the metals copper in the oxidation state +2, zinc in the oxidation state +2 and tin in the oxidation state +4. The electrolyte described here is said to contain a tenfold excess of tin and lead only to low-copper deposits.
EP 2037006 describes the electrolytic deposition of copper-tin-zinc alloys in a very particular atom ratio. The layers deposited have a composition which is said to be close to the formula Cu2ZnSn. The layers obtained in this way serve as base layer for the production of kesterite (CZTS or Cu2ZnSn(S,Se)4) which is a promising material for the production of photovoltaically active molecules (Solar Energy Materials & Solar Cells 201 1 , 95, 2136-2140; Chemical Physics Letters 201 1 , 501 , 619-622).
In a production process for such modules, a correspondingly produced Cu2ZnSn layer is subsequently converted by reaction with sulphur or sulphur-containing compounds at elevated temperatures into the corresponding kesterite phase (e.g.: Thin Solid Films 2009, 517, 2465-2468). Such a procedure is likewise addressed in EP 2037006. There, the specific electrolytically produced Cu2ZnSn deposits are obtained from an electrolyte to which particular disubstituted benzene derivatives have been added. The copper and zinc ions can be added as pyrophosphates to the electrolyte. The tin is preferably used as stannate.
The electrolytes described for the deposition of the ternary alloy of copper, tin and zinc all have only a low ability to deposit a desired ternary alloy composition of this type when, for example, specific additional additives are not added to the electrolyte or extremely high tin-IV concentrations are not present in the electrolyte. The additional complexity caused thereby makes the production and processing of the electrolytes unattractive. It was therefore an object of the present invention to provide an electrolyte and a corresponding process for the deposition of a ternary alloy of copper, tin and zinc, which are able to bring about the indicated deposition with a preferred stochiometry in a very optimal way. The electrolyte should ideally have a simple composition. The process and the electrolyte according to the invention should also be superior to the processes and electrolytes known from the prior art from ecological and economic points of view.
These objects and further objects which can be derived in an obvious manner from the prior art by a person skilled in the art are achieved by an electrolyte having the features of the present Claim 1 and by a corresponding process according to Claim 9. Preferred embodiments of the present invention may be found in the claims dependent on these two claims.
The use of an aqueous, cyanide-free, pyrophosphate-containing electrolyte containing the metals copper and zinc to be deposited in dissolved form and tin as dissolved stannate, where the electrolyte has a molar ratio of pyrophosphate anions to total copper and zinc ions in the range from >1 :2 to 20:1 and the molar ratio of copper ions to zinc ions in the electrolyte is in the range from 3:1 to 1 :4, for the electrolytic deposition of a copper-tin-zinc alloy leads, extremely surprisingly but no less advantageously, to achievement of the stated object. It has been found that an
advantageous ternary alloy composition can be achieved using the electrolyte described here when the pyrophosphate ions are present in excess over the copper and zinc ions in the electrolyte, when at the same time a particular ratio of copper to zinc ions is set and at the same time Sn is present as Sn4+. The electrolyte described here is noteworthy for the fact that obviously no further substances which influence the deposition of the ternary alloy have to be added to the electrolyte in order to bring about an appropriately composed deposition of copper-zinc-tin. In particular, the addition of reaction products of amines with epichlorohydrin as proposed in EP 21 16634 (mentioned at the outset) and the addition of disubstituted benzene derivatives known from EP 2037006 can be dispensed with. The composition of the ternary alloy of copper, tin and zinc can obviously be controlled in a simple manner via the abovementioned features alone. This has not yet been proposed in the prior art.
It is advantageous for the cyanide-free electrolyte to have a certain concentration of stabilizers. This task can be performed solely by the pyrophosphate anions present in the electrolyte. However, a person skilled in the art is free to add further stabilizers to the electrolyte. The concentration of pyrophosphate anions can be adjusted as desired within the abovementioned limits by a person skilled in the art and, as indicated above, dependent on the amount of copper and zinc ions used. A person skilled in the art will in this task be guided by, firstly, an optimal alloy composition being formed and, secondly, by the smallest possible amount of starting materials having to be employed for the deposition. The preferred range for the molar ratio of pyrophosphate anions to the sum of Cu and Zn ions addressed here should therefore be in the range from 1 :1.6 to 4:1. Particular preference is in this context given to a range from 1 :1 .4 to 2:1 .
According to the invention, the metals copper and zinc are present in ionically dissolved form in the present electrolyte. The copper can be added in the form of copper (I) salts or in the form of divalent copper salts or mixtures thereof to the electrolyte. Zinc will be present in the form of 2-valent ions in the electrolyte. The molar ratio of copper ions to zinc ions is preferably in the range from 2:1 to 1 :3. Very particular preference is given to a value of about 1 :1 - 1 :2. The tin is added as stannate salt, i.e. in the 4-valent form, to the electrolyte. Such stannate salts are well known to those skilled in the art. Particularly suitable stannate salts here are, for example, sodium stannate and potassium stannate. The ratios of the concentrations of copper and zinc ions relative to one another and also of the sum of these two ions to pyrophosphate anions are critical in determining the composition of the alloy deposited.
It is naturally also necessary for the tin used to be present in a particular ratio to the copper and zinc ions. The molar ratio of stannate salt used to the sum of copper and zinc ions should be 1 :1 - 6:1 , preferably 1 .5:1 - 4:1 and particularly preferably from 2:1 to 3:1. As regards the metals copper and zinc to be deposited, which are, as indicated, present in ionically dissolved form in the electrolyte, and the tin which is present in dissolved form as stannate, the concentration ranges of the metal in the electrolyte can be selected by a person skilled in the art. It has been found to be advantageous for the ion concentration of copper to be in the range from 0.1 to 10 g/l of electrolyte, the concentration of tin to be in the range from 0.5 to 20 g/l of electrolyte and the ion concentration of zinc to be in the range from 0.2 to 20 g/l of electrolyte. The concentration of copper is particularly preferably 0.3 - 5 g/l, very preferably 0.5 - 1 .0 g/l. The concentration of zinc is particularly preferably 0.3 - 10 g/l, very preferably 0.5 - 2.0 g/l. The concentration of tin is particularly preferably 2 - 15 g/l, very preferably 3.5 - 10 g/l. In a particularly advantageous embodiment, use is made of an electrolyte in which:
Copper is present in a concentration of 0.5 - 1 g/l,
Zinc is present in a concentration of 0.5 - 2 g/l,
Tin is present in a concentration of 3.5 - 7.5 g/l, and
in each case based on the metal.
As indicated above, the copper and zinc ions are present in dissolved form in the electrolyte. As compounds of these metals to be deposited which are soluble in water under the reaction conditions indicated, it is possible to employ compounds selected from the group consisting of pyrophosphates, carbonates, hydrogencarbonates, sulphites, sulphates, phosphates, nitrites, nitrates, halides, hydroxides, oxide- hydroxides, oxides and combinations thereof. Preference is given to using carbonate, hydrogencarbonates, sulphates or pyrophosphates. Very particular preference is given to the addition of sulphates in this context.
The electrolyte is operated in the slightly acidic to strongly alkaline range. The pH of the electrolyte is preferably in the range from 6 to 13, more preferably from 7.5 to 12 and very particularly preferably from 8 to 1 1 .5. The pH of the electrolyte according to the invention is especially preferably about 1 1. A person skilled in the art will know how to set such pH values in the electrolyte using appropriate buffer substances. Preferred
buffer substances are salts of weak organic or inorganic acids selected from the group consisting of phosphoric acid and citric acid.
Further additives (brighteners, wetting agents) selected from the group consisting of monocarboxylic and dicarboxylic acids, alkanesulphonic acids, betaines and aromatic nitro compounds can be added to the electrolyte. Such additives are adequately known for the present type of baths, in particular in the field of deposition of brass or bronze. As regards the amount and the materials used, reference may be made to the literature. Such additives are particularly preferably selected from the group consisting of oxalic acid, tartaric acid, citric acid and salts thereof. The present invention likewise provides a process for the electrolytic deposition of Cu- Zn-Sn alloy layers, in which the substrate to be coated is dipped as cathode into an electrolyte according to the invention and a flow of current is established between the anode and the cathode. It goes without saying that the embodiments of the electrolyte mentioned as preferred are analogously likewise preferred for the process. It is advantageous for the proportion of copper in the ternary alloy deposited to be in the range from 38 to 44% by weight, the proportion of tin to be in the range from 34 to 42% by weight and the proportion of zinc to be in the range from 16 to 26% by weight. Preference is given to alloys containing 39 - 42% by weight of Cu, very preferably about 40 - 41 % by weight. Preference is also given to alloys containing 19 - 23% by weight of Zn, very preferably about 21 % by weight. Preference is likewise given to alloys containing 36 - 40% by weight of Sn, very preferably about 38% by weight. The sum of the alloy constituents should be 100% by weight. The alloy deposited should have a thickness of 0.4 - 5 μηη, preferably 0.5 - 3 m and very particularly preferably 1 - 2 μηι. It may be pointed out that the alloy composition can likewise change with the temperature prevailing during the electrolysis. The electrolysis is therefore carried out in the range from 20 to 90°C, preferably from 30 to 60°C and very preferably about 45°C.
The composition of the ternary alloy of copper, tin and zinc can likewise change with the current density set during the electrolysis. It is advantageous to set a current density in the range from 0.1 to 5 ampere per square decimetre. The current density is
preferably from 0.2 to 1 .0 ampere per square decimetre, very preferably from 0.3 to 0.8 ampere per square decimetre.
As anode, it is possible to use any electrode which comes into question for this purpose to a person skilled in the art. Preference is given to using insoluble anodes (e.g. platinated titanium anodes or mixed metal oxide anodes). In this context, soluble anodes composed of a material selected from the group consisting of electrolytic copper, phosphorus-containing copper, tin, tin-copper alloy, zinc-copper alloy and zinc- tin-copper alloy or combinations of these anodes are likewise advantageous.
It is known from EP 2037006 cited at the outset that, inter alia, copper-tin-zinc alloys having a particular composition are suitable for the production of photovoltaic cells. As regards the production of thin film solar cells, reference may be made to the information given there and in EP 2336394. As regards the production of the solar cells, reference may likewise be made to the following literature:
Solar Energy Materials & Solar Cells, 95 (201 1 ) 2136-2140;
Chemical Physics Letters, 501 (201 1 ) 619-622;
Solar Energy Materials & Solar Cells, 93 (2009) 996-999;
Thin Solid Films, 517 (2009) 2465-2468;
Phys. Stat. Sol., 9 (2008) 1772-1778;
Phys. Stat. Sol., 5 (2009) 1266-1268;
Thin Solid Films, 517 (2009) 251 1 -2514.
The present invention therefore likewise provides a process for producing a thin film solar cell having a p-type absorption layer based on a CuxZnySnzSaSeb compound, where x = 1.5 - 2.5, y = 0.9 - 1 .5, z = 0.5 - 1 .1 , a = 0 - 4.2 and b = 0 - 4.2 and x + y + z and a + b are each about 4 (±0.2), wherein a CuxZnySnz alloy is produced by a process according to the invention and this layer is subsequently reacted with sulphur, a sulphur compound and/or a selenium compound in such a way that the corresponding compound is formed.
The alloy composition achieved by means of electrolysis preferably very closely approximates that corresponding to the alloy base material in the material kesterite (Cu2ZnSnS4). The layer produced by the process of the invention very preferably consists of a composition close to the formula Cu2ZnSn. From this, the desired
compound Cu2ZnSn(SeS)4 (CZTS) is produced by action of sulphur, selenium and/or appropriate compounds using appropriate processes as discussed in the literature.
In the light of the prior art, it was not possible to see that a process configured like the present process makes it possible to produce corresponding ternary alloy compositions by electrolytic deposition in such a simple way. In particular, it is surprising that the presence of particular ratios of copper and zinc ions to pyrophosphate anions and the ratio of copper ions and zinc ions relative to one another are responsible for this as long as Sn is present as Sn4+. In view of this, it appears to be particularly advantageous that the simple setting of the appropriate ratios obviously makes it possible to set the alloy composition deposited in an advantageous way. This was not to be expected in the light of the background of the known prior art.
Examples:
General procedure:
The ingredients mentioned below are dissolved in water and set to the appropriate pH. Any initial turbidity in the electrolyte disappears again after addition of the stannates. An electrolysis is subsequently carried out under the conditions indicated (e.g. 45°C, pH=1 1 , 0.8 A/dm2).
. Electrolyte composition according to the invention (Cu:Zn
90 g/l dipotassium hydrogenphosphate
15 g/l dipotassium oxalate monohydrate 0. .081 mol
1 .5 g/l sodium sulphite
7.5 g/l Sn as Na stannate 0. .063 mol
10 g/l potassium pyrophosphate (330.34 g/mol) 0. .030 mol
1 .0 g/l Cu (as Cu sulphate) (63.5 g/mol) 0. .016 mol
2.0 g/l Zn (as Zn sulphate) (65.3 g/mol) 0. .031 mol
0. .030 mol K pyrophosphate
0. .047 mol metal
Ratio of metal (Cu+Zn): K pyrophosphate = 1.6 : 1 pH 1 1 .0 45°C
0.8 A/dm2 -» Alloy 42% by weight Cu
36% by weight Sn
22% by weight Zn
2. Electrolyte composition according to the invention (Cu:Zn
90 g/l dipotassium hydrogenphosphate
15 g/l dipotassium oxalate monohydrate 0. .081 mol
1 .5 g/l sodium sulphite
7.2 g/l Sn as Na stannate 0. .060 mol
10 g/l potassium pyrophosphate (330.34 g/mol) 0. .030 mol
0.3 g/l Cu (as Cu sulphate) (63.5 g/mol) 0. .005 mol
1 .0 g/l Zn (as Zn sulphate) (65.3 g/mol) 0. .015 mol
0. .030 mol K pyrophosphate
0. .020 mol metal
Ratio of metal (Cu+Zn): K pyrophosphate = 1 : 1.5
pH 1 1 .0 45°C
0.7 A/dm2 -» Alloy 38% by weight Cu
37% by weight Sn
25% by weight Zn
3. Comparative experiment 2 as per EP2336394 (no additives):
95 g/l sodium phosphate x 12 H20
67 g/l disodium hydrogenphosphate x 7 H20
13.4 g/l dipotassium oxalate monohydrate 0.073 mol
1 .3 g/l sodium sulphite
3.22 g/l Sn as Na stannate 0.027 mol Sn
0.43 g/l Cu 0.0068 mol
= 1 .2 g/l Cu2P207 x 3H20 (M=354.8) 0.0034 mol pyrophosphate 0.28 g/l Zn 0.0042 mol
= 0.76 g/l Zn2P207 x 3H20 (M=358.4) 0.0021 mol pyrophosphate
0.0055 mol pyrophosphate 0.01 1 mol metal
Ratio of metal (Cu+Zn): pyrophosphate = 2 : 1
pH 1 1 .2 - 1 1 .8 45°C
Potentiostatic 1 .8 V
= Estimated current density: about 0.3 A/dm2
-» Alloy 52.6 atom% Cu = 46.3% by weight
16.7 atom% Sn = 26.7% by weight 30.7 atom% Zn = 27.0% by weight
4. Electrolyte composition according to the invention (Cu:Zn
90 g/l dipotassium hydrogenphosphate
15 g/l dipotassium oxalate monohydrate 0. .081 mol
1 .5 g/l sodium sulphite
3.6 g/l Sn as Na stannate 0. .030 mol Sn
10 g/l potassium pyrophosphate (330.34 g/mol) 0. .030 mol
0.5 g/l Cu (as Cu sulphate) (63.5 g/mol) 0. .008 mol
0.5 g/l Zn (as Zn sulphate) (65.3 g/mol) 0. .008 mol
0. .030 mol K pyrophosphate
0. .016 mol metal
Ratio of metal (Cu+Zn): K pyrophosphate = 1 : 1.9
pH 1 1 .0 45°C
0.4 A/dm2 Alloy 43% by weight Cu
41 % by weight Sn
16% by weight Zn
5. Electrolyte composition according to the invention (Cu :Zn = 2:1 ):
90 g/l dipotassium hydrogenphosphate
15 g/l dipotassium oxalate monohydrate 0.081 mol
1 .5 g/l sodium sulphite
3.6 g/l Sn as Na stannate 0.030 mol Sn
10 g/l potassium pyrophosphate (330.34 g/mol) 0.030 mol
1 .0 g/l Cu (as Cu sulphate) (63.5 g/mol) 0.016 mol
0.5 g/l Zn (as Zn sulphate) (65.3 g/mol) 0.008 mol
0.030 mol K pyrophosphate 0.024 mol metal
Ratio of metal (Cu+Zn): K pyrophosphate
pH 1 1 .0 45°C
1 .0 A/dm2 Alloy
Claims
Patent claims
Aqueous, cyanide-free, pyrophosphate-containing electrolyte for the electrolytic deposition of a copper-tin-zinc alloy, which contains the metals copper and zinc to be deposited in ionically dissolved form and tin as dissolved stannate, wherein the electrolyte has a molar ratio of pyrophosphate anions to total copper and zinc ions in the range from >1 :2 to 20:1 and the molar ratio of copper ions to zinc ions in the electrolyte is in the range from 3:1 to 1 :4.
Electrolyte according to Claim 1 ,
characterized in that
the molar ratio of pyrophosphate anions to Cu and Zn ions is from 1 :1.4 to 2:1 .
Electrolyte according to Claim 1 and/or 2,
characterized in that
the molar ratio of Cu ions to Zn ions is in the range from 2:1 to 1 :3.
Electrolyte according to one or more of Claims 1 to 3,
characterized in that
the metals copper and zinc to be deposited are present in ionically dissolved form and the tin is present as stannate, where the ion concentration of copper is in the range from 0.1 to 10 g/l of electrolyte, the ion concentration of tin is in the range from 0.5 to 20 g/L of electrolyte and the ion concentration of zinc is in the range from 0.2 to 20 g/l of electrolyte.
Electrolyte according to one or more of Claims 1 to 4,
characterized in that
the compounds of the metals to be deposited which are soluble in water under the given reaction conditions are selected from the group consisting of pyrophosphates, carbonates, hydrogencarbonates, sulphites, sulphates, phosphates, nitrites, nitrates, halides, hydroxides, oxide-hydroxides, oxides and combinations thereof.
6. Electrolyte according to one or more of Claims 1 to 5,
characterized in that
the pH of the electrolyte is in the range from 6 to 13.
7. Electrolyte according to one or more of Claims 1 to 6,
characterized in that
one or more stabilizing compounds selected from the group consisting of monocarboxylic and dicarboxylic acids, alkanesulphonic acids, betaines and aromatic nitro compounds are present.
8. Process for the electrolytic deposition of Cu-Zn-Sn alloy layers, wherein the
substrate to be coated is dipped as cathode into an electrolyte according to one or more of Claims 1 to 7 and a flow of current is established between the anode and the cathode. 9. Process according to Claim 8,
characterized in that
the proportion of copper in the alloy is in the range from 38 to 44% by weight, the proportion of tin is in the range from 34 to 42% by weight and the proportion of zinc is in the range from 16 to 26% by weight. 10. Process according to Claim 8 and/or 9,
characterized in that
the electrolyte temperature is maintained in the range from 20 to 90°C.
1 1 . Process according to one or more of Claims 8 to 10,
characterized in that
a current density in the range from 0.1 to 5 ampere per square decimetre is set.
12. Process according to one or more of Claims 8-1 1 ,
characterized in that insoluble anodes, e.g. platinated titanium anodes or mixed metal oxide anodes, or soluble anodes composed of a material selected from the group consisting of electrolytic copper, phosphorus-containing copper, tin, tin- copper alloy, zinc-copper alloy and zinc-tin-copper alloy or combinations of these anodes are used.
13. Process for producing a thin film solar cell having a p-type absorption layer based on a CuxZnySnzSaSeb compound, where x = 1 .5 - 2.5, y = 0.9 - 1.5, z = 0.5 -
1 .1 , a = 0 - 4 and b = 0 - 4 and x + y + z and a + b are each about 4 (±0.2), characterized in that a CuxZnySnz alloy is produced by a process according to one or more of Claims 8-12 and this layer is subsequently reacted with sulphur, a
sulphur compound and/or a selenium compound in such a way that the desired CuxZnySnzSaSeb compound is formed.
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DE102013226297B3 (en) * | 2013-12-17 | 2015-03-26 | Umicore Galvanotechnik Gmbh | Aqueous, cyanide-free electrolyte for the deposition of copper-tin and copper-tin-zinc alloys from an electrolyte and process for the electrolytic deposition of these alloys |
EP3144415A4 (en) * | 2014-05-15 | 2018-01-10 | Nippon Steel & Sumitomo Metal Corporation | Plating solution for pipe threaded coupling and manufacturing method for pipe threaded coupling |
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DE102021117095A1 (en) | 2021-07-02 | 2023-01-05 | Umicore Galvanotechnik Gmbh | Bronze layers as a substitute for precious metals |
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DE102013226297B3 (en) * | 2013-12-17 | 2015-03-26 | Umicore Galvanotechnik Gmbh | Aqueous, cyanide-free electrolyte for the deposition of copper-tin and copper-tin-zinc alloys from an electrolyte and process for the electrolytic deposition of these alloys |
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CN105829583A (en) * | 2013-12-17 | 2016-08-03 | 优美科电镀技术有限公司 | Deposition of copper-tin and copper-tin-zinc alloys from an electrolyte |
US20160348259A1 (en) * | 2013-12-17 | 2016-12-01 | Umicore Galvanotechnik Gmbh | Deposition of copper-tin and copper-tin-zinc alloys from an electrolyte |
EP3144415A4 (en) * | 2014-05-15 | 2018-01-10 | Nippon Steel & Sumitomo Metal Corporation | Plating solution for pipe threaded coupling and manufacturing method for pipe threaded coupling |
Also Published As
Publication number | Publication date |
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DE102011121799B4 (en) | 2013-08-29 |
DE102011121799A1 (en) | 2013-06-27 |
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