CN117684229A - Preparation of buried resistance copper foil and resistance test method thereof - Google Patents
Preparation of buried resistance copper foil and resistance test method thereof Download PDFInfo
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- CN117684229A CN117684229A CN202311513776.9A CN202311513776A CN117684229A CN 117684229 A CN117684229 A CN 117684229A CN 202311513776 A CN202311513776 A CN 202311513776A CN 117684229 A CN117684229 A CN 117684229A
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- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 title claims abstract description 131
- 239000011889 copper foil Substances 0.000 title claims abstract description 122
- 238000002360 preparation method Methods 0.000 title claims abstract description 17
- 238000010998 test method Methods 0.000 title abstract description 17
- 238000009713 electroplating Methods 0.000 claims abstract description 82
- 238000005406 washing Methods 0.000 claims abstract description 50
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 37
- 238000000034 method Methods 0.000 claims abstract description 32
- 238000001035 drying Methods 0.000 claims abstract description 19
- 238000004519 manufacturing process Methods 0.000 claims abstract description 4
- 239000000243 solution Substances 0.000 claims description 101
- 238000005530 etching Methods 0.000 claims description 60
- 229910001096 P alloy Inorganic materials 0.000 claims description 46
- OFNHPGDEEMZPFG-UHFFFAOYSA-N phosphanylidynenickel Chemical compound [P].[Ni] OFNHPGDEEMZPFG-UHFFFAOYSA-N 0.000 claims description 46
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 42
- 239000000853 adhesive Substances 0.000 claims description 25
- 230000001070 adhesive effect Effects 0.000 claims description 25
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 24
- 239000000654 additive Substances 0.000 claims description 24
- 238000005554 pickling Methods 0.000 claims description 24
- 239000002985 plastic film Substances 0.000 claims description 24
- 229920006255 plastic film Polymers 0.000 claims description 24
- 238000007747 plating Methods 0.000 claims description 24
- 238000012360 testing method Methods 0.000 claims description 24
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 20
- 239000003112 inhibitor Substances 0.000 claims description 19
- 239000003381 stabilizer Substances 0.000 claims description 19
- 239000000080 wetting agent Substances 0.000 claims description 19
- 239000011259 mixed solution Substances 0.000 claims description 18
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 15
- KWSLGOVYXMQPPX-UHFFFAOYSA-N 5-[3-(trifluoromethyl)phenyl]-2h-tetrazole Chemical compound FC(F)(F)C1=CC=CC(C2=NNN=N2)=C1 KWSLGOVYXMQPPX-UHFFFAOYSA-N 0.000 claims description 13
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 13
- 239000004327 boric acid Substances 0.000 claims description 13
- 229910001379 sodium hypophosphite Inorganic materials 0.000 claims description 13
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 claims description 10
- MHAJPDPJQMAIIY-UHFFFAOYSA-N Hydrogen peroxide Chemical compound OO MHAJPDPJQMAIIY-UHFFFAOYSA-N 0.000 claims description 10
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 10
- 229910052802 copper Inorganic materials 0.000 claims description 10
- 239000010949 copper Substances 0.000 claims description 10
- 239000001509 sodium citrate Substances 0.000 claims description 10
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 claims description 10
- RRIWRJBSCGCBID-UHFFFAOYSA-L nickel sulfate hexahydrate Chemical compound O.O.O.O.O.O.[Ni+2].[O-]S([O-])(=O)=O RRIWRJBSCGCBID-UHFFFAOYSA-L 0.000 claims description 9
- 229940116202 nickel sulfate hexahydrate Drugs 0.000 claims description 9
- 239000000523 sample Substances 0.000 claims description 9
- XMVONEAAOPAGAO-UHFFFAOYSA-N sodium tungstate Chemical compound [Na+].[Na+].[O-][W]([O-])(=O)=O XMVONEAAOPAGAO-UHFFFAOYSA-N 0.000 claims description 9
- 229920002873 Polyethylenimine Polymers 0.000 claims description 8
- 239000007864 aqueous solution Substances 0.000 claims description 8
- GSPKZYJPUDYKPI-UHFFFAOYSA-N diethoxy sulfate Chemical compound CCOOS(=O)(=O)OOCC GSPKZYJPUDYKPI-UHFFFAOYSA-N 0.000 claims description 8
- JRBPAEWTRLWTQC-UHFFFAOYSA-N dodecylamine Chemical compound CCCCCCCCCCCCN JRBPAEWTRLWTQC-UHFFFAOYSA-N 0.000 claims description 8
- 239000002904 solvent Substances 0.000 claims description 8
- 239000000758 substrate Substances 0.000 claims description 8
- 230000000996 additive effect Effects 0.000 claims description 7
- CVHZOJJKTDOEJC-UHFFFAOYSA-N saccharin Chemical compound C1=CC=C2C(=O)NS(=O)(=O)C2=C1 CVHZOJJKTDOEJC-UHFFFAOYSA-N 0.000 claims description 7
- 229940081974 saccharin Drugs 0.000 claims description 7
- 235000019204 saccharin Nutrition 0.000 claims description 7
- 239000000901 saccharin and its Na,K and Ca salt Substances 0.000 claims description 7
- 239000002202 Polyethylene glycol Substances 0.000 claims description 6
- 229920001223 polyethylene glycol Polymers 0.000 claims description 6
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 5
- 235000019270 ammonium chloride Nutrition 0.000 claims description 5
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 5
- ORTQZVOHEJQUHG-UHFFFAOYSA-L copper(II) chloride Chemical compound Cl[Cu]Cl ORTQZVOHEJQUHG-UHFFFAOYSA-L 0.000 claims description 5
- 239000000463 material Substances 0.000 claims description 5
- 239000004642 Polyimide Substances 0.000 claims description 4
- 229920001721 polyimide Polymers 0.000 claims description 4
- 239000002253 acid Substances 0.000 claims description 3
- 239000003522 acrylic cement Substances 0.000 claims description 3
- 229920006332 epoxy adhesive Polymers 0.000 claims description 3
- 229910000402 monopotassium phosphate Inorganic materials 0.000 claims description 3
- 235000019796 monopotassium phosphate Nutrition 0.000 claims description 3
- 229910000403 monosodium phosphate Inorganic materials 0.000 claims description 3
- 235000019799 monosodium phosphate Nutrition 0.000 claims description 3
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N phenol group Chemical group C1(=CC=CC=C1)O ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 claims description 3
- 229920002635 polyurethane Polymers 0.000 claims description 3
- 239000004814 polyurethane Substances 0.000 claims description 3
- 230000001105 regulatory effect Effects 0.000 claims description 3
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 claims description 3
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 claims description 2
- 238000010438 heat treatment Methods 0.000 claims description 2
- PJNZPQUBCPKICU-UHFFFAOYSA-N phosphoric acid;potassium Chemical compound [K].OP(O)(O)=O PJNZPQUBCPKICU-UHFFFAOYSA-N 0.000 claims description 2
- 239000000956 alloy Substances 0.000 abstract description 16
- 238000000151 deposition Methods 0.000 abstract description 13
- 230000008569 process Effects 0.000 abstract description 11
- 238000004544 sputter deposition Methods 0.000 abstract description 7
- 239000000126 substance Substances 0.000 abstract description 6
- 230000006698 induction Effects 0.000 abstract description 3
- 238000004886 process control Methods 0.000 abstract description 3
- 230000003647 oxidation Effects 0.000 abstract description 2
- 238000007254 oxidation reaction Methods 0.000 abstract description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 23
- 230000000052 comparative effect Effects 0.000 description 14
- 238000001723 curing Methods 0.000 description 14
- 229910052759 nickel Inorganic materials 0.000 description 11
- 229910045601 alloy Inorganic materials 0.000 description 10
- 229920002799 BoPET Polymers 0.000 description 8
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 8
- 229910052698 phosphorus Inorganic materials 0.000 description 8
- 239000011574 phosphorus Substances 0.000 description 8
- 230000001276 controlling effect Effects 0.000 description 7
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 description 6
- 239000008139 complexing agent Substances 0.000 description 6
- 230000008021 deposition Effects 0.000 description 6
- 239000001632 sodium acetate Substances 0.000 description 6
- 235000017281 sodium acetate Nutrition 0.000 description 6
- 230000003746 surface roughness Effects 0.000 description 6
- 230000007547 defect Effects 0.000 description 3
- 229920000139 polyethylene terephthalate Polymers 0.000 description 3
- 230000009467 reduction Effects 0.000 description 3
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 description 3
- 229910052721 tungsten Inorganic materials 0.000 description 3
- 239000010937 tungsten Substances 0.000 description 3
- USFZMSVCRYTOJT-UHFFFAOYSA-N Ammonium acetate Chemical compound N.CC(O)=O USFZMSVCRYTOJT-UHFFFAOYSA-N 0.000 description 2
- 239000005695 Ammonium acetate Substances 0.000 description 2
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 230000009471 action Effects 0.000 description 2
- 230000004913 activation Effects 0.000 description 2
- 229940043376 ammonium acetate Drugs 0.000 description 2
- 235000019257 ammonium acetate Nutrition 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000006172 buffering agent Substances 0.000 description 2
- 230000007797 corrosion Effects 0.000 description 2
- 238000005260 corrosion Methods 0.000 description 2
- 239000003792 electrolyte Substances 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 description 2
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 description 2
- 229940053662 nickel sulfate Drugs 0.000 description 2
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 238000002161 passivation Methods 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000012827 research and development Methods 0.000 description 2
- 238000005496 tempering Methods 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- VEQPNABPJHWNSG-UHFFFAOYSA-N Nickel(2+) Chemical compound [Ni+2] VEQPNABPJHWNSG-UHFFFAOYSA-N 0.000 description 1
- PHJJWPXKTFKKPD-UHFFFAOYSA-N [Ni+3].[O-]P([O-])[O-] Chemical compound [Ni+3].[O-]P([O-])[O-] PHJJWPXKTFKKPD-UHFFFAOYSA-N 0.000 description 1
- ACVSDIKGGNSZDR-UHFFFAOYSA-N [P].[W].[Ni] Chemical compound [P].[W].[Ni] ACVSDIKGGNSZDR-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000003486 chemical etching Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- ICHUMRJJFKQBGK-UHFFFAOYSA-N dodecyl ethoxy sulfate Chemical compound CCCCCCCCCCCCOS(=O)(=O)OOCC ICHUMRJJFKQBGK-UHFFFAOYSA-N 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000004070 electrodeposition Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000003292 glue Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- -1 hydrogen ions Chemical class 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 238000013035 low temperature curing Methods 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 229910001453 nickel ion Inorganic materials 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 1
- ACVYVLVWPXVTIT-UHFFFAOYSA-M phosphinate Chemical compound [O-][PH2]=O ACVYVLVWPXVTIT-UHFFFAOYSA-M 0.000 description 1
- 230000010287 polarization Effects 0.000 description 1
- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 description 1
- LWIHDJKSTIGBAC-UHFFFAOYSA-K potassium phosphate Substances [K+].[K+].[K+].[O-]P([O-])([O-])=O LWIHDJKSTIGBAC-UHFFFAOYSA-K 0.000 description 1
- 230000002035 prolonged effect Effects 0.000 description 1
- 238000004062 sedimentation Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
Abstract
The invention discloses a preparation method of a buried resistance copper foil and a resistance test method thereof, belonging to the technical field of printed circuit boards. So as to solve the problems of large production investment of the vacuum sputtering method and the chemical induction deposition method and large process control difficulty of the electroplating method. The preparation method of the buried resistance copper foil comprises the steps of performing oxidation pretreatment on a base copper foil, electroplating a resistance layer, washing with water and drying; the resistance test method of the buried resistance copper foil comprises the following steps: the resistor layer and the supporting layer are bonded and cured, etched, washed, baked and tested for resistance; the invention adopts the electroplating process to deposit a layer of resistance alloy material on the copper foil, and common electroplating equipment can meet the requirements.
Description
Technical Field
The invention belongs to the technical field of printed circuit boards, and particularly relates to a preparation method of a buried resistance copper foil and a resistance test method thereof.
Background
The PCB embedded resistance technology is used as a method for replacing the surface resistance patch, so that the increasingly tense surface space of the PCB can be saved, and the use of the nickel-phosphorus alloy embedded resistance copper foil is one of the ways for realizing the embedded resistance board. The structure of the nickel-phosphorus alloy embedded resistance copper foil is generally shown in fig. 1, and the structure of the nickel-phosphorus alloy embedded resistance copper foil is shown in fig. 1, wherein the nickel-phosphorus alloy embedded resistance copper foil is a special copper foil material prepared by sputtering or electroplating a layer of nickel-phosphorus alloy 2 on a copper foil 1. Wherein the thickness of the nickel-phosphorus alloy resistor layer is mostly controlled between 0.1 and 1 mu m.
The current processes for producing the buried resistor copper foil can be divided into three main types: the first method is to deposit a layer of resistance alloy material on the copper foil by adopting a vacuum sputtering mode; the second is to deposit a layer of resistance alloy material on the copper foil by using a chemical induction deposition mode; the third is to electroplate a layer of resistive alloy material on the copper foil using an electrochemical process.
Among them, the sputtering method requires the use of a vacuum sputtering apparatus, the deposition rate thereof is relatively limited, and the investment cost for the apparatus is very high. In the method disclosed in Chinese patent CN102324294A, the chemical induced deposition method is similar to the method disclosed in the method of embedded resistor material, palladium chloride activation is needed before the nickel-phosphorus alloy layer material with the porous structure is chemically plated, and then thermal tempering is needed, wherein noble metal palladium activation is needed in the whole method, the cost is high, the subsequent thermal tempering affects the speed, and the requirement of industrial production cannot be met. Finally, the electroplating process has the inherent advantages, the requirements on equipment are not high, the common electroplating equipment can meet the requirements, but the electroplating process has the defect that compared with chemical plating and sputtering, the process control difficulty is higher, the application of the electroplating process in the field of the buried copper foil is limited by the defect, and the technical problem in the research and development direction is to break through the defect of the electroplating process and obtain a stable electroplating system.
For the test method of the embedded resistance copper foil resistor produced by the method, a test area needs to be set during layout, such as a test method of a PCB with embedded resistance and embedded resistance in China patent CN104619114A, which is more complicated.
Based on the problems in the background technology, research and development personnel propose a preparation method and a resistance test method of a buried resistance copper foil.
Disclosure of Invention
The invention aims to provide a preparation method and a resistance test method of a buried resistance copper foil, which are used for solving the problems of large production investment of a vacuum sputtering method and a chemical induction deposition method and large process control difficulty of an electroplating method.
The invention also aims to provide a resistance testing method of the buried resistance copper foil, so as to solve the problem of complicated resistance testing steps of the buried resistance copper foil.
In order to solve the problems, the technical scheme of the invention is as follows:
a preparation method of a buried resistance copper foil comprises the following steps:
s1, performing deoxidation pretreatment on a base copper foil:
acid washing copper foil;
s2, electroplating a resistor layer:
firstly, preparing electroplating solution by taking pure water as a solvent and adding the following components of the electroplating solution;
secondly, adding additives, wherein the additives comprise one or more of wetting agents, inhibitors and stabilizers;
thirdly, regulating the pH of the electroplating solution;
finally, electroplating is carried out;
the thickness of the nickel-phosphorus alloy ultrathin resistor layer after electroplating is 0.1-1 mu m;
s3, washing and drying:
taking out the electroplated embedded resistance copper foil, washing with pure water, and drying to prepare the embedded resistance copper foil, wherein the roughness Rz of the embedded resistance copper foil is 0.48-9.96 mu m.
Further, the thickness of the copper foil substrate in the step S1 is 18-35 mu m;
the pickling time is 3 to 20 seconds at the pickling temperature of 20 to 40 ℃;
the pickling solution is 10-20wt% sulfuric acid aqueous solution.
Further, in the electroplating solution prepared in the step S2, the concentration of nickel sulfate hexahydrate is 90-300g/L, the concentration of sodium citrate is 30-400g/L, the concentration of sodium hypophosphite is 3-30g/L, the concentration of boric acid is 10-50g/L, the concentration of phosphoric acid is 6-50g/L, and the concentration of sodium tungstate is 0-200g/L.
Further, in S2:
the additive comprises the following components:
the wetting agent is as follows: saccharin and polyethylene glycol are selected from the following components in solution: 0.1-1g/L;
the inhibitor is as follows: one of the laurylamine ethoxysulfate and the polyethyleneimine is selected, and the content of the laurylamine ethoxysulfate and the polyethyleneimine in the solution is as follows: 0.05-0.3g/L;
the stabilizer is as follows: acetate, potassium dihydrogen phosphate, sodium dihydrogen phosphate and the like, and the contents in the solution are as follows: 0.5-10g/L;
adjusting the pH of the electroplating solution to 1-5 by sulfuric acid or sodium hydroxide;
the electroplating temperature is controlled at 40-80 ℃; the electroplating current density is 1-15A/dm 2 。
Further, the S3 is washed by pure water for 2 to 5 seconds, the washing pressure is 0.5 to 2MPa, and the baking is carried out for 5 to 20 minutes at 80 ℃.
The resistance test method for preparing the buried resistance copper foil by the method comprises the following steps:
s4, bonding and solidifying the resistance layer and the supporting layer;
bonding an ultrathin resistance layer of the embedded resistance copper foil on a plastic film, heating and curing at a curing temperature of 40 ℃ for 12 hours;
s5, etching;
completely etching the copper layer by using an etching solution;
s6, washing and baking;
taking out the plastic film, washing the plastic film cleanly, and drying the plastic film at 40-100 ℃ for 1-5min, wherein the plastic film is adhered with the nickel-phosphorus alloy resistor layer;
s7, testing the resistor;
and the four-probe sheet resistance tester is used for testing the resistance of the nickel-phosphorus alloy layer, so that the sheet resistance of the nickel-phosphorus alloy resistance layer can be obtained.
Further, in S5: the etching solution is a mixed solution of hydrogen peroxide, sulfuric acid, citric acid and pure water, and the mass ratio of the etching solution to the mixed solution is 1% -5%, 3% -10%, 1% -10% and 75% -95%, respectively;
the etching temperature is 30-60 ℃ and the etching time is 1-30 min.
Further, in S5: the etching solution can also be a mixed solution of copper chloride, ammonium chloride, ammonia water and pure water, and the mass ratio of the etching solution to the mixed solution is 5% -15%, 3% -15%, 20% -50% and 20% -72% respectively;
the etching temperature is 40-60 ℃ and the etching time is 1-30 min.
Further, in S4: the plastic film is one of PET, PI, PP, PVC materials;
the adhesive comprises one or more of epoxy adhesive, modified phenolic adhesive, polyurethane adhesive, acrylic adhesive, polyimide adhesive and UV adhesive.
The beneficial effects of the invention are as follows:
(1) The method breaks through the technical problem of the traditional electroplating process, and the method takes sodium hypophosphite as a phosphorus source, so that positive monovalent phosphorus is easy to codeposit, has high reduction potential and can promote nickel deposition. Boric acid is used as a buffering agent and a surface passivating agent of metallic nickel, and the passivation of nickel improves the content of metal oxide in the alloy resistance layer and further improves the resistivity. After the complexing agent, the wetting agent, the stabilizer and the inhibitor are reasonably matched, the electroplating solution has no impurity precipitation, can be recycled for multiple times, and the deposited alloy has small stress in the resistance layer, is uniform and compact, has no surface crack and has stable resistivity.
The preparation principle of depositing a layer of resistance alloy material on the copper foil by adopting the electroplating process has low requirements on equipment, and common electroplating equipment can meet the requirements.
(2) According to the invention, copper foils with different thicknesses and roughness are used, a layer of resistance alloy material is electroplated on the copper foils, and the prepared buried resistance copper foil can meet different binding force and downstream application requirements; standard profile copper foil (Rz about 5-10 μm) is applied to laminates of general FR-4, polyimide and the like; the low-profile copper foil (Rz is about 2-7 mu m) is mainly applied to the circuit board fields of high-frequency, high-density interconnection HDI, narrow linewidth line distance and the like; ultra low profile (Rz about 0.5-2 μm) copper foil is used in the circuit board fields of high frequency, high speed, narrow tolerance, low loss, packaging, etc.
(3) In the preparation method of the invention, the functions of each substance in the components of the electroplating solution are as follows:
the main function of nickel sulfate hexahydrate is to provide nickel ions; on the other hand, nickel chloride is used in the conventional nickel electroplating industry, and nickel sulfate is used instead of nickel chloride, so that the nickel sulfate reduces corrosion to the anode and the cathode because chloride ions corrode the anode and the cathode.
Sodium citrate is a main complexing agent, so that the concentration of free electrolyte in the plating solution is controlled, the cathode polarization is improved, and the service life of the plating solution is prolonged.
The sodium hypophosphite is used as a phosphorus source, the valence of phosphorus is positive and monovalent, and the sodium hypophosphite is easy to reduce, so that the co-deposition speed of phosphorus can be increased, and the phosphorus content in a plating layer is increased; in addition, under the acidic condition, the sodium hypophosphite has great reduction potential (the reduction potential is < -0.7V), so that the sodium hypophosphite has strong reducibility, can promote the deposition of nickel and improves the electrodeposition speed of a cathode.
The two weak acids of phosphoric acid and boric acid are used as buffering agents of the invention, and besides adjusting the pH value of the plating solution, the phosphoric acid can inhibit the oxidation of hypophosphite at the anode, inhibit the precipitation of nickel phosphite, provide hydrogen ions at the interface of the cathode and promote the deposition of phosphorus. And boric acid has passivation effect on metal nickel, and the boric acid is firstly contacted with the cathode to enable the metal nickel on the surface of the alloy resistance layer of the cathode to generate active sites, wherein the active sites can adsorb oxygen dissolved in plating solution, and the oxygen is further reduced under the action of electrons and combined with the nickel to generate oxidized nickel. The oxidized nickel is an insulator, and the resistivity of the plating layer is effectively improved by the oxidized nickel in the plating layer.
The alloy resistor layer of the invention contains not only nickel and phosphorus, but also tungsten, and sodium tungstate provides tungsten element in the invention. The sheet resistance of the resistive layer is inversely related to the thickness, and the thickness of the plating layer must be reduced in order to obtain a high sheet resistance; in the manufacturing process of the circuit board, the copper layer is subjected to chemical etching to form a circuit, tungsten has extremely strong corrosion resistance, and the resistance layer can be protected from being corroded by etching liquid, so that the sheet resistance of the resistance layer is kept stable.
Besides, complexing agent, wetting agent, stabilizer and inhibitor are added into the electroplating solution. The alloy resistor layer has very thin thickness, the surface is extremely easy to crack, a complexing agent and a wetting agent are required to be used for improving the uniformity of nickel-phosphorus co-deposition or nickel-phosphorus-tungsten co-deposition, reducing the internal stress of a plating layer and avoiding the generation of surface cracks; the stabilizer can make the current density distribution of the cathode more uniform, promote the uniform flow of electrolyte under the action of a uniform electric field, and promote the compactness and uniformity of cathode deposition; the inhibitor is added and attached to the surface of the cathode, so that abnormal rise of the current density of the micro-area is inhibited, and on one hand, sedimentation of impurity metal ions in the plating solution is reduced. The additives are matched within a certain concentration range (0.005-10 g/L), and all the components and the content thereof are compounded to form a stable electroplating system, so that the sheet resistance value of the final embedded resistance copper foil resistor layer is more stable, and the sheet resistance tolerance is less than 5%.
(4) The resistance test method provided by the invention does not need to laminate the embedded resistance copper foil board, expose, develop and etch the embedded resistance copper foil board into specific patterns, and then perform resistance test. According to the resistance testing method, an alloy resistance layer of the embedded resistance copper foil is adhered to a supporting layer in a low-temperature curing mode, then the copper layer is completely etched by using etching liquid, one surface of the alloy resistance layer, which is combined with the copper foil, is exposed, the alloy resistance layer is dried by washing, and finally the sheet resistance of the alloy resistance layer is measured by using four probes.
Drawings
FIG. 1 is a schematic diagram of a structure of a buried resistance copper foil according to the present invention;
fig. 2 is a physical photograph and an electron microscope image of the buried resistance copper foil product 3 prepared in example 3 of the present invention;
FIG. 3 is a flow chart of the present invention;
the reference numerals are as follows: 1-copper foil, 2-nickel-phosphorus alloy.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, based on the embodiments of the invention, which are apparent to those of ordinary skill in the art without inventive faculty, are intended to be within the scope of the invention.
Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention.
Example 1
The flow is as shown in fig. 3:
a preparation method of a buried resistance copper foil comprises the following steps:
s1, performing deoxidation pretreatment on a base copper foil:
taking a copper foil with the substrate thickness of 18 mu m and the surface roughness Rz of 3.5 mu m, and pickling for 20s at a pickling temperature of 25 ℃;
the pickling solution is a 10wt% sulfuric acid aqueous solution;
s2, electroplating a resistor layer:
first, a plating solution was prepared by adding the following components to pure water as a solvent.
In the prepared electroplating solution, the concentration of nickel sulfate hexahydrate is 200g/L, the concentration of sodium citrate is 230g/L, the concentration of sodium hypophosphite is 16g/L, the concentration of boric acid is 35g/L, the concentration of phosphoric acid is 30g/L, and the concentration of sodium tungstate is 110g/L.
Secondly, adding additives, wherein the additives comprise one or more of wetting agents, inhibitors and stabilizers;
the wetting agent is as follows: saccharin, its content in solution is: 0.5g/L;
the inhibitor is as follows: dodecylamine ethoxysulfate, the content of which in the solution is: 0.15g/L;
the stabilizer is as follows: sodium acetate, the content of which in solution is: 3g/L.
Again, the pH of the plating solution is adjusted to 2 with sulfuric acid or sodium hydroxide.
Finally, controlling the electroplating temperature at 65 ℃; the electroplating current density was 10A/dm 2 。
The thickness of the nickel-phosphorus alloy ultrathin resistor layer after electroplating is 0.3 mu m.
S3, washing and drying:
taking out the electroplated embedded resistance copper foil, washing with pure water for 3s, washing with water under the pressure of 0.5MPa, and baking at 80 ℃ for 20min to prepare the embedded resistance copper foil product 1.
At this time, the copper foil roughness of the product 1 was tested, and the roughness Rz thereof was 3.51 μm.
The resistance test method of the buried resistance copper foil comprises the following steps:
s4, bonding and solidifying the resistance layer and the supporting layer;
tightly adhering the resistance layer on the plastic film by using an adhesive, wherein the curing temperature is 40 ℃ and the curing time is 12 hours;
the plastic film is PET; the adhesive is an epoxy adhesive.
S5, etching;
the copper layer is completely etched away using an etching solution.
The etching solution is a mixed solution of copper chloride, ammonium chloride, ammonia water and pure water, and the mass ratio of the etching solution to the mixed solution is 10 percent to 35 percent to 45 percent respectively;
the etching temperature was 40℃and the etching time was 30min.
S6, washing and baking;
taking out the PET film, washing the PET film cleanly, and then baking the PET film at 40 ℃ for 5min, wherein the PET film is adhered with the nickel-phosphorus alloy resistor layer;
s7, testing the resistor;
the resistance of the nickel-phosphorus alloy layer is tested by using a four-probe sheet resistance tester, the sheet resistance of the nickel-phosphorus alloy resistance layer is 32.3 omega/≡, and the resistance value fluctuates by 3.5%.
Example 2
A preparation method of a buried resistance copper foil comprises the following steps:
s1, performing deoxidation pretreatment on a base copper foil:
taking a copper foil with the substrate thickness of 18-mu m and the surface roughness Rz of 3.5 mu m, and pickling for 3s at a pickling temperature of 20 ℃;
the pickling solution is a 15wt% sulfuric acid aqueous solution;
s2, electroplating a resistor layer:
first, a plating solution was prepared by adding the following components to pure water as a solvent.
In the prepared electroplating solution, the concentration of nickel sulfate hexahydrate is 150g/L, the concentration of sodium citrate is 30g/L, the concentration of sodium hypophosphite is 30g/L, the concentration of boric acid is 10g/L, the concentration of phosphoric acid is 50g/L, and the concentration of sodium tungstate is 0g/L.
Secondly, adding additives, wherein the additives comprise one or more of wetting agents, inhibitors and stabilizers;
the wetting agent is as follows: saccharin, its content in solution is: 0.1g/L;
the inhibitor is as follows: dodecylamine ethoxysulfate, the content of which in the solution is: 0.05g/L;
the stabilizer is as follows: the content of the monopotassium phosphate in the solution is as follows: 0.5g/L.
Again, the pH of the plating solution was adjusted to 3 with sulfuric acid or sodium hydroxide.
Finally, controlling the electroplating temperature at 40 ℃; the electroplating current density was 1A/dm 2 。
The thickness of the nickel-phosphorus alloy ultrathin resistor layer after electroplating is 0.1 mu m.
S3, washing and drying:
taking out the electroplated embedded resistance copper foil, washing with pure water for 2s, washing with water under the pressure of 1.8MPa, and baking at 80 ℃ for 6min to prepare the embedded resistance copper foil product 2.
At this time, the copper foil roughness of the product 2 was tested, and the roughness Rz thereof was 3.48 μm.
The resistance test method of the buried resistance copper foil comprises the following steps:
s4, bonding and solidifying the resistance layer and the supporting layer;
tightly adhering the resistance layer on the plastic film by using an adhesive, wherein the curing temperature is 40 ℃ and the curing time is 12 hours;
the plastic film is PP; the adhesive is a modified phenolic adhesive.
S5, etching;
the copper layer is completely etched away using an etching solution.
The etching solution can also be a mixed solution of copper chloride, ammonium chloride, ammonia water and pure water, and the mass ratio of the etching solution is 5 percent to 3 percent to 20 percent to 72 percent respectively;
the etching temperature was 50℃and the etching time was 5min.
S6, washing and baking;
taking out the PP film, washing the PP film cleanly, and then baking the PP film for 1min at the temperature of 100 ℃, wherein the PP film is adhered with the nickel-phosphorus alloy resistor layer;
s7, testing the resistor;
the resistance of the nickel-phosphorus alloy layer is tested by using a four-probe sheet resistance tester, the sheet resistance of the nickel-phosphorus alloy resistance layer is 96.2 omega/≡, and the resistance value fluctuates by 4.5%.
Example 3
A preparation method of a buried resistance copper foil comprises the following steps:
s1, performing deoxidation pretreatment on a base copper foil:
taking a copper foil with the substrate thickness of 18 mu m and the surface roughness Rz of 3.5 mu m, and pickling for 20s at a pickling temperature of 30 ℃;
the pickling solution is a sulfuric acid aqueous solution with the concentration of 20 weight percent;
s2, electroplating a resistor layer:
first, a plating solution was prepared by adding the following components to pure water as a solvent.
In the prepared electroplating solution, the concentration of nickel sulfate hexahydrate is 300g/L, the concentration of sodium citrate is 360g/L, the concentration of sodium hypophosphite is 4g/L, the concentration of boric acid is 50g/L, the concentration of phosphoric acid is 12g/L, and the concentration of sodium tungstate is 180g/L.
Secondly, adding additives, wherein the additives comprise one or more of wetting agents, inhibitors and stabilizers;
the wetting agent is as follows: saccharin, its content in solution is: 0.9g/L;
the inhibitor is as follows: dodecylamine ethoxysulfate, the content of which in the solution is: 0.3g/L;
the stabilizer is as follows: ammonium acetate, the content of which in solution is: 10g/L.
Again, the pH of the plating solution is adjusted to 1 with sulfuric acid or sodium hydroxide.
Finally, controlling the electroplating temperature at 60 ℃; the electroplating current density was 15A/dm 2 。
The thickness of the nickel-phosphorus alloy ultrathin resistor layer after electroplating is 0.4 mu m.
S3, washing and drying:
taking out the electroplated embedded resistance copper foil, washing with pure water for 3s, washing with water under the pressure of 0.8MPa, and baking at 80 ℃ for 15min to prepare the embedded resistance copper foil product 3.
The photo of the embedded copper foil product 3 is shown in fig. 2 (a), and the surface color is uniform; as shown in fig. 2 (b), the surface of the copper foil is uniformly distributed, so that the original appearance of the copper foil is not negatively affected in the electroplating process, and good binding force with the prepreg in the lamination process can be ensured.
At this time, the copper foil roughness of the product 3 was tested, and the roughness Rz thereof was 3.52 μm.
The resistance test method of the buried resistance copper foil comprises the following steps:
s4, bonding and solidifying the resistance layer and the supporting layer;
tightly adhering the resistance layer on the plastic film by using an adhesive, wherein the curing temperature is 40 ℃ and the curing time is 12 hours;
the plastic film is PET; the adhesive is polyurethane adhesive.
S5, etching;
the copper layer is completely etched away using an etching solution.
The etching solution can also be a mixed solution of copper chloride, ammonium chloride, ammonia water and pure water, and the mass ratio of the etching solution is 15 percent to 50 percent to 20 percent respectively;
the etching temperature was 60℃and the etching time was 1min.
S6, washing and baking;
taking out the PET film, washing the PET film cleanly, and then baking the PET film for 3min at the temperature of 70 ℃, wherein the PET film is adhered with the nickel-phosphorus alloy resistor layer;
s7, testing the resistor;
the resistance of the nickel-phosphorus alloy layer is tested by using a four-probe sheet resistance tester, the sheet resistance of the nickel-phosphorus alloy resistance layer is 24.8Ω/≡, and the resistance value fluctuates by 3.0%.
Example 4
A preparation method of a buried resistance copper foil comprises the following steps:
s1, performing deoxidation pretreatment on a base copper foil:
taking a copper foil with the substrate thickness of 35 mu m and the surface roughness Rz of 5.5 mu m, and pickling for 10s at a pickling temperature of 35 ℃;
the pickling solution is a 10wt% sulfuric acid aqueous solution;
s2, electroplating a resistor layer:
first, a plating solution was prepared by adding the following components to pure water as a solvent.
In the prepared electroplating solution, the concentration of nickel sulfate hexahydrate is 250g/L, the concentration of sodium citrate is 260g/L, the concentration of sodium hypophosphite is 16g/L, the concentration of boric acid is 40g/L, the concentration of phosphoric acid is 30g/L, and the concentration of sodium tungstate is 150g/L.
Secondly, adding additives, wherein the additives comprise one or more of wetting agents, inhibitors and stabilizers;
the wetting agent is as follows: polyethylene glycol, which is present in the solution in an amount of: 0.4g/L;
the inhibitor is as follows: polyethyleneimine, the content of which in solution is: 0.15g/L;
the stabilizer is as follows: ammonium acetate, the content of which in solution is: 3g/L.
Again, the pH of the plating solution was adjusted to 3 with sulfuric acid or sodium hydroxide.
Finally, controlling the electroplating temperature at 70 ℃; the electroplating current density was 12A/dm 2 。
The thickness of the nickel-phosphorus alloy ultrathin resistor layer after electroplating is 0.2 mu m.
S3, washing and drying:
taking out the electroplated embedded resistance copper foil, washing for 4s by pure water, and baking for 10min at 80 ℃ under the water washing pressure of 1.5MPa to prepare the embedded resistance copper foil product 4.
At this time, the copper foil roughness of the product 4 was tested, and the roughness Rz thereof was 5.46.
The resistance test method of the buried resistance copper foil comprises the following steps:
s4, bonding and solidifying the resistance layer and the supporting layer;
tightly adhering the resistance layer on the plastic film by using an adhesive, wherein the curing temperature is 40 ℃ and the curing time is 12 hours;
the plastic film is PI; the adhesive is an acrylic adhesive.
S5, etching;
the copper layer is completely etched away using an etching solution.
The etching solution is a mixed solution of hydrogen peroxide, sulfuric acid, citric acid and pure water, and the mass ratio of the etching solution to the mixed solution is respectively 3 percent to 7 percent to 5 percent to 85 percent;
the etching temperature was 60℃and the etching time was 10min.
S6, washing and baking;
taking out the PI film, washing with water, and baking at 50 ℃ for 4min, wherein the PI film is adhered with the nickel-phosphorus alloy resistor layer;
s7, testing the resistor;
the resistance of the nickel-phosphorus alloy layer is tested by using a four-probe sheet resistance tester, the sheet resistance of the nickel-phosphorus alloy resistance layer is 49.5 omega/≡, and the resistance value fluctuates by 3.5%.
Example 5
A preparation method of a buried resistance copper foil comprises the following steps:
s1, performing deoxidation pretreatment on a base copper foil:
taking a copper foil with the substrate thickness of 35 mu m and the surface roughness Rz of 0.5 mu m, and pickling for 3s at a pickling temperature of 40 ℃;
the pickling solution is a 15wt% sulfuric acid aqueous solution;
s2, electroplating a resistor layer:
first, a plating solution was prepared by adding the following components to pure water as a solvent.
In the prepared electroplating solution, the concentration of nickel sulfate hexahydrate is 90g/L, the concentration of sodium citrate is 50g/L, the concentration of sodium hypophosphite is 30g/L, the concentration of boric acid is 10g/L, the concentration of phosphoric acid is 50g/L, and the concentration of sodium tungstate is 0g/L.
Secondly, adding additives, wherein the additives comprise one or more of wetting agents, inhibitors and stabilizers;
the wetting agent is as follows: polyethylene glycol, which is present in the solution in an amount of: 0.2g/L;
the inhibitor is as follows: polyethyleneimine, the content of which in solution is: 0.05g/L;
the stabilizer is as follows: sodium dihydrogen phosphate, the content of which in the solution is: 0.5g/L.
Again, the pH of the plating solution was adjusted to 3 with sulfuric acid or sodium hydroxide.
Finally, controlling the electroplating temperature at 75 ℃; the electroplating current density was 2A/dm 2 。
The thickness of the nickel-phosphorus alloy ultrathin resistor layer after electroplating is 0.1 mu m.
S3, washing and drying:
taking out the electroplated embedded resistance copper foil, washing for 5s by pure water, washing under the pressure of 2MPa, and baking at 80 ℃ for 5min to prepare the embedded resistance copper foil product 5.
At this time, the copper foil roughness of the product 5 was tested, and the roughness Rz thereof was 0.48 μm.
The resistance test method of the buried resistance copper foil comprises the following steps:
s4, bonding and solidifying the resistance layer and the supporting layer;
tightly adhering the resistance layer on the plastic film by using an adhesive, wherein the curing temperature is 40 ℃ and the curing time is 12 hours;
the plastic film is PVC; the adhesive is polyimide adhesive.
S5, etching;
the copper layer is completely etched away using an etching solution.
The etching solution is a mixed solution of hydrogen peroxide, sulfuric acid, citric acid and pure water, and the mass ratio of the etching solution to the mixed solution is 1 percent to 3 percent to 1 percent to 95 percent respectively;
the etching temperature was 40℃and the etching time was 30min.
S6, washing and baking;
taking out the PVC film, washing the PVC film cleanly, and then baking the PVC film at 80 ℃ for 2min, wherein the PVC film is adhered with the nickel-phosphorus alloy resistor layer;
s7, testing the resistor;
the resistance of the nickel-phosphorus alloy layer is tested by using a four-probe sheet resistance tester, the sheet resistance of the nickel-phosphorus alloy resistance layer is 97Ω/≡, and the resistance value fluctuates by 4.8%.
Example 6
A preparation method of a buried resistance copper foil comprises the following steps:
s1, performing deoxidation pretreatment on a base copper foil:
taking copper foil with the substrate thickness of 35 mu m and the surface roughness Rz of 10 mu m, and pickling for 20s at a pickling temperature of 25 ℃;
the pickling solution is a sulfuric acid aqueous solution with the concentration of 20 weight percent;
s2, electroplating a resistor layer:
first, a plating solution was prepared by adding the following components to pure water as a solvent.
In the prepared electroplating solution, the concentration of nickel sulfate hexahydrate is 300g/L, the concentration of sodium citrate is 400g/L, the concentration of sodium hypophosphite is 3g/L, the concentration of boric acid is 50g/L, the concentration of phosphoric acid is 6g/L, and the concentration of sodium tungstate is 200g/L.
Secondly, adding additives, wherein the additives comprise one or more of wetting agents, inhibitors and stabilizers;
the wetting agent is as follows: polyethylene glycol, which is present in the solution in an amount of: 1g/L;
the inhibitor is as follows: polyethyleneimine, the content of which in solution is: 0.3g/L;
the stabilizer is as follows: sodium acetate, the content of which in solution is: 6g/L.
Again, the pH of the plating solution was adjusted to 1.5 with sulfuric acid or sodium hydroxide.
Finally, controlling the electroplating temperature at 80 ℃; the electroplating current density was 8A/dm 2 。
The thickness of the nickel-phosphorus alloy ultrathin resistor layer after electroplating is 0.5 mu m.
S3, washing and drying:
taking out the electroplated embedded resistance copper foil, washing with pure water for 3s, washing with water under the pressure of 1MPa, and baking at 80 ℃ for 18min to prepare the embedded resistance copper foil product 6.
At this time, the copper foil roughness of the product 6 was tested, and the roughness Rz thereof was 9.96 μm.
The resistance test method of the buried resistance copper foil comprises the following steps:
s4, bonding and solidifying the resistance layer and the supporting layer;
tightly adhering the resistance layer on the plastic film by using an adhesive, wherein the curing temperature is 40 ℃ and the curing time is 12 hours;
the plastic film is PI; the adhesive is a UV glue.
S5, etching;
the copper layer is completely etched away using an etching solution.
The etching solution is a mixed solution of hydrogen peroxide, sulfuric acid, citric acid and pure water, and the mass ratio of the etching solution to the mixed solution is 5 percent to 10 percent to 75 percent respectively;
the etching temperature was 30℃and the etching time was 10min.
S6, washing and baking;
taking out the PI film, washing with water, and baking at 60 ℃ for 4min, wherein the PI film is adhered with the nickel-phosphorus alloy resistor layer;
s7, testing the resistor;
the resistance of the nickel-phosphorus alloy layer is tested by using a four-probe sheet resistance tester, the sheet resistance of the nickel-phosphorus alloy resistance layer is 20Ω/≡, and the resistance value fluctuates by 3.3%.
Comparative example 1
The difference from example 1 is that:
s2, electroplating a resistor layer:
when the additive is added, saccharin and dodecyl ethoxysulfate are removed, and only sodium acetate is added, wherein the content of the sodium acetate in the solution is also as follows: 3g/L.
The thickness of the nickel-phosphorus alloy ultrathin resistor layer after electroplating is 1 mu m.
S3, washing and drying:
and washing and drying to obtain the comparative buried resistance copper foil product 1.
At this time, the copper foil roughness of the comparative buried resistance copper foil product 1 was tested, and the roughness Rz thereof was 3.53 μm.
And finally, carrying out resistance test on the resistance-embedded copper foil, wherein the sheet resistance of the nickel-phosphorus alloy resistance layer is 8.6Ω/≡and the resistance value fluctuation is 5.3%.
The sheet resistance of this comparative example was significantly reduced and the fluctuation in resistance was increased as compared with example 1.
Comparative example 2
The difference from example 4 is that:
s2, electroplating a resistor layer:
in the prepared electroplating solution, the concentration of boric acid is 0g/L.
The polyethyleneimine is removed from the added additive, and only the polyethylene glycol and the sodium acetate are remained.
The thickness of the nickel-phosphorus alloy ultrathin resistor layer after electroplating is 1 mu m.
S3, washing and drying:
and washing and drying to obtain the comparative buried resistance copper foil product 2.
At this time, the copper foil roughness of the comparative buried resistance copper foil product 2 was tested, and the roughness Rz thereof was 5.48 μm.
And finally, carrying out resistance test on the resistance-embedded copper foil, wherein the sheet resistance of the nickel-phosphorus alloy resistance layer is 8.7 omega/≡and the resistance value fluctuates by 5.1%.
The sheet resistance of this comparative example was significantly reduced and the fluctuation in resistance was increased as compared with example 4.
Comparative example 3
The difference from example 1 is that:
s2, electroplating a resistor layer:
in the prepared electroplating solution, the concentration of sodium citrate is 0g/L.
The dodecylamine ethoxysulfate was removed from the additive, and only saccharin and sodium acetate remained.
The thickness of the nickel-phosphorus alloy ultrathin resistor layer after electroplating is 1 mu m.
S3, washing and drying:
and washing and drying to obtain the contrast buried resistance copper foil product 3.
At this time, the copper foil roughness of the comparative buried resistance copper foil product 3 was tested, and the roughness Rz thereof was 5.49 μm.
And finally, carrying out resistance test on the buried copper foil, wherein the sheet resistance of the nickel-phosphorus alloy resistance layer is 8.3 omega/≡and the resistance value fluctuates by 5.5%.
The sheet resistance of this comparative example was significantly reduced and the fluctuation in resistance was increased as compared with example 1.
Comparative verification of the above examples with the comparative examples can be seen:
the electroplating uniformity of the alloy resistance layer can be adjusted by regulating and controlling the amounts of the complexing agent and the additive in the electroplating system, so that the fluctuation of the sheet resistance is controlled. Proper complexing agent and additive are favorable for stabilizing the electroplating system and reducing the fluctuation of sheet resistance.
In a word, the invention truly establishes a stable electroplating system, and the square resistance value of the produced resistance-embedded copper foil resistance layer is more stable, and the resistance tolerance is 4.8% at the highest and is obviously lower than that of each comparative example.
Claims (9)
1. The preparation method of the buried resistance copper foil is characterized by comprising the following steps:
s1, performing deoxidation pretreatment on a base copper foil:
acid washing copper foil;
s2, electroplating a resistor layer:
firstly, preparing electroplating solution by taking pure water as a solvent and adding the following components of the electroplating solution;
secondly, adding additives, wherein the additives comprise one or more of wetting agents, inhibitors and stabilizers;
thirdly, regulating the pH of the electroplating solution;
finally, electroplating is carried out;
the thickness of the nickel-phosphorus alloy ultrathin resistor layer after electroplating is 0.1-1 mu m;
s3, washing and drying:
taking out the electroplated embedded resistance copper foil, washing with pure water, and drying to prepare the embedded resistance copper foil, wherein the roughness Rz of the embedded resistance copper foil is 0.48-9.96 mu m.
2. The method for producing a buried resistor copper foil according to claim 1, wherein the thickness of the copper foil substrate in S1 is 18 to 35 μm;
the pickling time is 3 to 20 seconds at the pickling temperature of 20 to 40 ℃;
the pickling solution is 10-20wt% sulfuric acid aqueous solution.
3. The method according to claim 2, wherein the plating solution prepared in S2 has a nickel sulfate hexahydrate concentration of 90 to 300g/L, a sodium citrate concentration of 30 to 400g/L, a sodium hypophosphite concentration of 3 to 30g/L, a boric acid concentration of 10 to 50g/L, a phosphoric acid concentration of 6 to 50g/L, and a sodium tungstate concentration of 0 to 200g/L.
4. The method for preparing a buried resistor copper foil and testing the resistance thereof according to claim 3, wherein in S2:
the additive comprises the following components:
the wetting agent is as follows: saccharin and polyethylene glycol are selected from the following components in solution: 0.1-1g/L;
the inhibitor is as follows: one of the laurylamine ethoxysulfate and the polyethyleneimine is selected, and the content of the laurylamine ethoxysulfate and the polyethyleneimine in the solution is as follows: 0.05-0.3g/L;
the stabilizer is as follows: acetate, potassium dihydrogen phosphate, sodium dihydrogen phosphate and the like, and the contents in the solution are as follows: 0.5-10g/L;
adjusting the pH of the electroplating solution to 1-5 by sulfuric acid or sodium hydroxide;
the electroplating temperature is controlled at 40-80 ℃; the electroplating current density is 1-15A/dm 2 。
5. The method for preparing a buried resistor copper foil and a resistance test thereof according to claim 4, wherein the pure water in S3 is used for 2-5S, the water washing pressure is 0.5-2MPa, and the copper foil is baked at 80 ℃ for 5-20min.
6. The method for testing the resistance of the buried resistance copper foil prepared by the method according to any one of claims 1 to 5, wherein the method comprises the following steps:
s4, bonding and solidifying the resistance layer and the supporting layer;
bonding an ultrathin resistance layer of the embedded resistance copper foil on a plastic film, heating and curing at a curing temperature of 40 ℃ for 12 hours;
s5, etching;
completely etching the copper layer by using an etching solution;
s6, washing and baking;
taking out the plastic film, washing the plastic film cleanly, and drying the plastic film at 40-100 ℃ for 1-5min, wherein the plastic film is adhered with the nickel-phosphorus alloy resistor layer;
s7, testing the resistor;
and the four-probe sheet resistance tester is used for testing the resistance of the nickel-phosphorus alloy layer, so that the sheet resistance of the nickel-phosphorus alloy resistance layer can be obtained.
7. The method for testing the electrical resistance of a buried copper foil according to claim 6, wherein in S5: the etching solution is a mixed solution of hydrogen peroxide, sulfuric acid, citric acid and pure water, and the mass ratio of the etching solution to the mixed solution is 1% -5%, 3% -10%, 1% -10% and 75% -95%, respectively;
the etching temperature is 30-60 ℃ and the etching time is 1-30 min.
8. The method for testing the electrical resistance of a buried copper foil according to claim 6, wherein in S5: the etching solution can also be a mixed solution of copper chloride, ammonium chloride, ammonia water and pure water, and the mass ratio of the etching solution to the mixed solution is 5% -15%, 3% -15%, 20% -50% and 20% -72% respectively;
the etching temperature is 40-60 ℃ and the etching time is 1-30 min.
9. The method for testing the electrical resistance of a buried copper foil according to claim 7 or 8, wherein in S4: the plastic film is one of PET, PI, PP, PVC materials;
the adhesive comprises one or more of epoxy adhesive, modified phenolic adhesive, polyurethane adhesive, acrylic adhesive, polyimide adhesive and UV adhesive.
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| CN202311513776.9A CN117684229A (en) | 2023-11-14 | 2023-11-14 | Preparation of buried resistance copper foil and resistance test method thereof |
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