CN115747907B - Multifunctional composite electroplated layer of optocoupler lead frame and preparation method - Google Patents
Multifunctional composite electroplated layer of optocoupler lead frame and preparation method Download PDFInfo
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- CN115747907B CN115747907B CN202211603089.1A CN202211603089A CN115747907B CN 115747907 B CN115747907 B CN 115747907B CN 202211603089 A CN202211603089 A CN 202211603089A CN 115747907 B CN115747907 B CN 115747907B
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- 239000002131 composite material Substances 0.000 title claims abstract description 20
- 238000002360 preparation method Methods 0.000 title claims abstract description 8
- 238000007747 plating Methods 0.000 claims abstract description 296
- 239000010410 layer Substances 0.000 claims abstract description 224
- 229910052709 silver Inorganic materials 0.000 claims abstract description 101
- 239000004332 silver Substances 0.000 claims abstract description 101
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 95
- 229910052802 copper Inorganic materials 0.000 claims abstract description 68
- 239000010949 copper Substances 0.000 claims abstract description 68
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 66
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 58
- 238000009713 electroplating Methods 0.000 claims abstract description 26
- 239000002346 layers by function Substances 0.000 claims abstract description 17
- KERTUBUCQCSNJU-UHFFFAOYSA-L nickel(2+);disulfamate Chemical compound [Ni+2].NS([O-])(=O)=O.NS([O-])(=O)=O KERTUBUCQCSNJU-UHFFFAOYSA-L 0.000 claims abstract description 15
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 184
- 229910052759 nickel Inorganic materials 0.000 claims description 94
- 238000000034 method Methods 0.000 claims description 29
- 239000002253 acid Substances 0.000 claims description 24
- 239000003795 chemical substances by application Substances 0.000 claims description 23
- 230000004913 activation Effects 0.000 claims description 20
- 238000005282 brightening Methods 0.000 claims description 20
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 18
- 239000011248 coating agent Substances 0.000 claims description 17
- 238000000576 coating method Methods 0.000 claims description 17
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 16
- 230000037452 priming Effects 0.000 claims description 16
- NNFCIKHAZHQZJG-UHFFFAOYSA-N potassium cyanide Chemical compound [K+].N#[C-] NNFCIKHAZHQZJG-UHFFFAOYSA-N 0.000 claims description 14
- LFAGQMCIGQNPJG-UHFFFAOYSA-N silver cyanide Chemical compound [Ag+].N#[C-] LFAGQMCIGQNPJG-UHFFFAOYSA-N 0.000 claims description 14
- 229940098221 silver cyanide Drugs 0.000 claims description 14
- 239000000654 additive Substances 0.000 claims description 13
- 230000000996 additive effect Effects 0.000 claims description 11
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 11
- 239000004327 boric acid Substances 0.000 claims description 11
- 238000005406 washing Methods 0.000 claims description 11
- AFVFQIVMOAPDHO-UHFFFAOYSA-N Methanesulfonic acid Chemical compound CS(O)(=O)=O AFVFQIVMOAPDHO-UHFFFAOYSA-N 0.000 claims description 10
- 229910021586 Nickel(II) chloride Inorganic materials 0.000 claims description 10
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 claims description 10
- 229910000365 copper sulfate Inorganic materials 0.000 claims description 8
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 claims description 8
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 230000003287 optical effect Effects 0.000 claims description 7
- LGQLOGILCSXPEA-UHFFFAOYSA-L nickel sulfate Chemical compound [Ni+2].[O-]S([O-])(=O)=O LGQLOGILCSXPEA-UHFFFAOYSA-L 0.000 claims description 6
- 229910000363 nickel(II) sulfate Inorganic materials 0.000 claims description 6
- -1 silver ions Chemical class 0.000 claims description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 claims description 5
- 230000002378 acidificating effect Effects 0.000 claims description 5
- KXZJHVJKXJLBKO-UHFFFAOYSA-N chembl1408157 Chemical compound N=1C2=CC=CC=C2C(C(=O)O)=CC=1C1=CC=C(O)C=C1 KXZJHVJKXJLBKO-UHFFFAOYSA-N 0.000 claims description 5
- 238000006243 chemical reaction Methods 0.000 claims description 5
- AICMYQIGFPHNCY-UHFFFAOYSA-J methanesulfonate;tin(4+) Chemical compound [Sn+4].CS([O-])(=O)=O.CS([O-])(=O)=O.CS([O-])(=O)=O.CS([O-])(=O)=O AICMYQIGFPHNCY-UHFFFAOYSA-J 0.000 claims description 5
- 239000011241 protective layer Substances 0.000 claims description 5
- 239000000758 substrate Substances 0.000 claims description 5
- DOBRDRYODQBAMW-UHFFFAOYSA-N copper(i) cyanide Chemical compound [Cu+].N#[C-] DOBRDRYODQBAMW-UHFFFAOYSA-N 0.000 claims description 4
- 238000005238 degreasing Methods 0.000 claims description 4
- PGGZKNHTKRUCJS-UHFFFAOYSA-N methanesulfonic acid;tin Chemical compound [Sn].CS(O)(=O)=O PGGZKNHTKRUCJS-UHFFFAOYSA-N 0.000 claims description 3
- 230000003213 activating effect Effects 0.000 claims description 2
- 238000002955 isolation Methods 0.000 claims description 2
- 238000004806 packaging method and process Methods 0.000 abstract description 19
- 230000001965 increasing effect Effects 0.000 abstract description 11
- 239000000243 solution Substances 0.000 description 107
- 239000000463 material Substances 0.000 description 65
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 35
- 239000008367 deionised water Substances 0.000 description 32
- 229910021641 deionized water Inorganic materials 0.000 description 32
- 238000005507 spraying Methods 0.000 description 28
- 238000011010 flushing procedure Methods 0.000 description 21
- 238000012360 testing method Methods 0.000 description 18
- 238000005187 foaming Methods 0.000 description 16
- 230000008569 process Effects 0.000 description 15
- UJAXHWXDLUXGII-UHFFFAOYSA-N [Ni].[Cu].[Ag].[Ni] Chemical compound [Ni].[Cu].[Ag].[Ni] UJAXHWXDLUXGII-UHFFFAOYSA-N 0.000 description 11
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 9
- IEXGYCVLNVITKV-UHFFFAOYSA-N [Ni].[Ni].[Cu].[Sn] Chemical compound [Ni].[Ni].[Cu].[Sn] IEXGYCVLNVITKV-UHFFFAOYSA-N 0.000 description 9
- 239000007788 liquid Substances 0.000 description 7
- 238000005476 soldering Methods 0.000 description 7
- 238000003466 welding Methods 0.000 description 7
- 239000003792 electrolyte Substances 0.000 description 5
- 230000001681 protective effect Effects 0.000 description 5
- 238000005452 bending Methods 0.000 description 4
- 238000004140 cleaning Methods 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- OPXJEFFTWKGCMW-UHFFFAOYSA-N copper nickel Chemical compound [Ni].[Ni].[Cu] OPXJEFFTWKGCMW-UHFFFAOYSA-N 0.000 description 4
- 239000000203 mixture Substances 0.000 description 4
- 239000000843 powder Substances 0.000 description 4
- XPFCXIKQEQOMMW-UHFFFAOYSA-N 2-[(3,4-dichlorophenyl)methyl]-1h-benzimidazole Chemical group C1=C(Cl)C(Cl)=CC=C1CC1=NC2=CC=CC=C2N1 XPFCXIKQEQOMMW-UHFFFAOYSA-N 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound 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 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 238000001035 drying Methods 0.000 description 3
- 239000008151 electrolyte solution Substances 0.000 description 3
- 238000007602 hot air drying Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012858 packaging process Methods 0.000 description 3
- 229940083256 peripheral vasodilators nicotinic acid and derivative Drugs 0.000 description 3
- 229920000136 polysorbate Polymers 0.000 description 3
- 238000012805 post-processing Methods 0.000 description 3
- 239000003223 protective agent Substances 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 239000007921 spray Substances 0.000 description 3
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 3
- PQJKKINZCUWVKL-UHFFFAOYSA-N [Ni].[Cu].[Ag] Chemical compound [Ni].[Cu].[Ag] PQJKKINZCUWVKL-UHFFFAOYSA-N 0.000 description 2
- VRUVRQYVUDCDMT-UHFFFAOYSA-N [Sn].[Ni].[Cu] Chemical compound [Sn].[Ni].[Cu] VRUVRQYVUDCDMT-UHFFFAOYSA-N 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000002452 interceptive effect Effects 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000002035 prolonged effect Effects 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- JKEOXMAHHRTVEX-UHFFFAOYSA-J [Ni++].[Ni++].NS([O-])(=O)=O.NS([O-])(=O)=O.NS([O-])(=O)=O.NS([O-])(=O)=O Chemical compound [Ni++].[Ni++].NS([O-])(=O)=O.NS([O-])(=O)=O.NS([O-])(=O)=O.NS([O-])(=O)=O JKEOXMAHHRTVEX-UHFFFAOYSA-J 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- DLDJFQGPPSQZKI-UHFFFAOYSA-N but-2-yne-1,4-diol Chemical compound OCC#CCO DLDJFQGPPSQZKI-UHFFFAOYSA-N 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000003487 electrochemical reaction Methods 0.000 description 1
- 238000005868 electrolysis reaction Methods 0.000 description 1
- 230000001804 emulsifying effect Effects 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000006260 foam Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 150000002815 nickel Chemical class 0.000 description 1
- CLDVQCMGOSGNIW-UHFFFAOYSA-N nickel tin Chemical compound [Ni].[Sn] CLDVQCMGOSGNIW-UHFFFAOYSA-N 0.000 description 1
- 239000002736 nonionic surfactant Substances 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- XSUMSESCSPMNPN-UHFFFAOYSA-N propane-1-sulfonate;pyridin-1-ium Chemical compound C1=CC=NC=C1.CCCS(O)(=O)=O XSUMSESCSPMNPN-UHFFFAOYSA-N 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000007670 refining Methods 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 125000005504 styryl group Chemical group 0.000 description 1
- 239000008399 tap water Substances 0.000 description 1
- 235000020679 tap water Nutrition 0.000 description 1
- DZXKSFDSPBRJPS-UHFFFAOYSA-N tin(2+);sulfide Chemical compound [S-2].[Sn+2] DZXKSFDSPBRJPS-UHFFFAOYSA-N 0.000 description 1
- 239000000080 wetting agent Substances 0.000 description 1
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/50—Manufacturing or production processes characterised by the final manufactured product
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- Electroplating Methods And Accessories (AREA)
Abstract
The invention discloses a multifunctional composite electroplated layer of an optocoupler lead frame and a preparation method thereof, and relates to the technical field of electroplated layers of optocoupler lead frames. The functional layers of the conductive functional area of the optocoupler lead frame are silver layers, and the functional layers of the non-conductive functional area of the optocoupler lead frame are tin layers. According to the invention, the nickel sulfamate layer is plated between the copper plating layer and the silver plating layer and between the copper plating layer and the tin plating layer, so that the binding force between the plating layers can be increased, the plating layers are not easy to fall off, the high-temperature resistance stability of the plating layers is increased, and the quality of the plating layers is improved. According to the invention, silver plating of the conductive functional area and tin plating of the pins are completed before packaging, so that damage to an optocoupler product caused by secondary electrotinning after packaging is avoided, the problem of low efficiency caused by repeated reciprocating packaging factories and electroplating factories is avoided, the delivery period is shortened, and the labor and time cost is saved.
Description
Technical Field
The invention relates to the technical field of electroplating layers of optocoupler lead frames, in particular to a multifunctional composite electroplating layer of an optocoupler lead frame and a preparation method thereof.
Background
Existing optocoupler lead frame plating processes typically include pretreatment processes (electrolytic degreasing and activation) and nickel and silver plating; as the lead frame base material is developed from copper base material to iron base material, the surface smoothness of the base material is inconsistent, the plating layer is few in variety, the surface brightness is low, the cost is increased by improving the thickness of the nickel plating layer, the weldability is affected, and the quality requirement of high-end electronic products is difficult to adapt.
After silver plating is finished, the lead frame is delivered to a packaging factory for completing products such as surface mounting, bonding wires, dispensing, curing packaging and the like, then delivered to an electroplating factory for tinning pins, and then returned to the packaging factory for testing, so that the production efficiency is reduced for two places in a round-trip manner for a plurality of times, the delivery period is prolonged, and potential damage to the optocoupler products is generated in the electroplating process after packaging.
Disclosure of Invention
The invention aims to provide a multifunctional composite electroplated layer of an optocoupler lead frame and a preparation method thereof, so as to solve the problems in the prior art. The coating prepared by the method is full and smooth, and meets the quality requirement of high-end electronic products; the silver plating and the pin tin plating are completed before packaging, so that the damage to an optocoupler product in the electroplating process after packaging is avoided, and the problem of low efficiency caused by repeated reciprocating packaging factories and electroplating factories is also avoided.
In order to achieve the above object, the present invention provides the following solutions:
according to one of the technical schemes, the multifunctional composite electroplated layer of the optocoupler lead frame sequentially comprises a nickel layer, a copper layer, a nickel layer and a functional layer according to the direction of the substrate layer to the surface of the electroplated layer, wherein the functional layer of the conductive functional area of the optocoupler lead frame is a silver layer, and the functional layer of the non-conductive functional area of the optocoupler lead frame is a tin layer.
Further, according to the direction of the substrate layer to the surface of the electroplated layer, a nickel layer with the thickness of 1-3 mu m, a copper layer with the thickness of 3-8 mu m, a nickel layer with the thickness of 1-3 mu m and a functional layer with the thickness of 1.6-8 mu m are sequentially arranged; when the functional layer is a silver layer, the thickness of the functional layer is 1.6-5 mu m; when the functional layer is a tin layer, the thickness of the functional layer is 5-8 μm.
The second technical scheme of the invention is that the preparation method of the multifunctional composite electroplated layer of the optocoupler lead frame comprises the following steps:
step 1, priming nickel plating is carried out on an optocoupler lead frame to obtain an optocoupler lead frame with a plated priming nickel layer;
step 2, pre-plating alkaline copper on the optocoupler lead frame plated with the bottoming nickel layer to obtain the pre-plated alkaline copper optocoupler lead frame;
step 3, carrying out acid copper plating on the pre-plated alkaline copper optocoupler lead frame to obtain an electroplated copper optocoupler lead frame;
step 4, nickel plating is carried out on the optocoupler lead frame with the electroplated copper layer, so that the optocoupler lead frame with the electroplated nickel layer is obtained; the nickel plating solution comprises 60-90g/L of nickel sulfamate, 8-15g/L of nickel chloride, 40-50g/L of boric acid, 0.5-2mL/L of nickel plating main brightening agent and 60-120mL/L of nickel plating softener according to the concentration;
step 5, pre-plating silver on the photo-coupler lead frame with the electroplated nickel layer to obtain a pre-plated photo-coupler lead frame;
step 6, silver plating is carried out on the conductive functional area of the pre-silver plated optocoupler lead frame, and an electroplated silver optocoupler lead frame is obtained;
step 7, carrying out desilvering treatment (desilvering treatment is pre-silvering) on the non-conductive functional area of the electroplated silver optocoupler lead frame to obtain the desilvered optocoupler lead frame;
and 8, carrying out non-conductive functional area tin plating on the optical coupler lead frame subjected to silver removal treatment to obtain the optical coupler lead frame with the multifunctional composite electroplated layer.
In the step 4, the reason for adopting the nickel sulfamate is that the electroplated layer formed by the nickel sulfamate has small stress and good flexibility, and the nickel sulfamate layer is additionally plated between the copper layer and the silver layer and between the copper layer and the tin layer, so that the fullness of the electroplated layer can be enhanced, the electroplated layer is smooth and clean, and the quality of the electroplated layer is improved; meanwhile, the binding force between the plating layers can be increased, so that the plating layers are not easy to fall off, and the high-temperature resistance stability of the plating layers is improved. If nickel sulfate commonly used in the field is used for replacing nickel sulfamate in the step, the plating layer has larger stress and insufficient flexibility, and the bonding force between the plating layers and the high-temperature resistance stability are affected.
In the step 4, the concentration of each component in the plating solution is defined to be 60-90g/L, 8-15g/L and 40-50g/L of boric acid, which are determined by repeated experiments, the concentration of each component is higher than that of the middle nickel plating layer, the crystallization speed is accelerated, the particles are coarse, the stress is increased, the flexibility is poor, the stability of the silver layer is affected, the nickel salt in the plating solution is increased along with the loss of a plated product, the waste is caused, the plating layer is thinner, the electroplating time is required to be increased when the plating layer is thinner, and the plating layer cannot be formed when the plating layer is too low.
Further, in the step 1, according to the concentration, the plating solution for priming nickel plating comprises 150-180g/L of nickel sulfate, 45-50g/L of nickel chloride, 45-50g/L of boric acid, 0.5-2mL/L of nickel plating main brightening agent and 60-120mL/L of nickel plating softener; the temperature of the plating solution for priming nickel plating is 55-65 ℃ and the pH value is 3.8-4.4; the current density of the priming nickel plating is 2-6A/dm 2 The thickness of the plating layer of the priming nickel plating is 1-3 mu m.
Further, in the step 2, according to the concentration, the plating solution for preplating the alkaline copper comprises 15-30g/L of cuprous cyanide and 80-120g/L of sodium cyanide; the plating solution temperature of the preplating alkaline copper is 35-45 ℃; the current density of the preplating alkaline copper is 4-10A/dm 2 The thickness of the preplating alkaline copper coating is 1-3 mu m.
Further, in the step 3, according to the concentration, the plating solution of the acid copper plating comprises 180-220g/L of copper sulfate, 30-40mL/L of sulfuric acid, 80-120mg/L of chloride ion, 5-8mL/L of acid copper cylinder opener and 0.4-0.8mL/L of brightening agent (A); the temperature of the plating solution for acidic copper plating is 22-28 ℃; the current density of the acid copper plating is 2-6A/dm 2 The thickness of the acid copper plating layer is 2-5 μm.
Further, in the step 4, the temperature of the plating solution for nickel plating is 60-65 ℃, the pH value is 3.8-4.4, and the current density of the nickel plating is 2-6A/dm 2 The thickness of the nickel plating layer is 1-3 mu m.
Further, in the step 5, the plating solution for pre-silver plating contains potassium cyanide and silver cyanide; the concentration of the potassium cyanide is 80-120g/L; the concentration of the silver cyanide in the plating solution is 4-8g/L according to silver ions; the plating solution temperature of the pre-silver plating is 20-35 ℃; the current density of the pre-silver plating is 2-6A/dm 2 The thickness of the plating layer of the pre-silver plating is 0.1-0.2 mu m.
Further, in the step 6, the plating solution for plating silver on the conductive functional area comprises potassium cyanide, silver cyanide and additives; the concentration of the potassium cyanide is 80-120g/L; the concentration of the silver cyanide is 10-20g/L according to silver ions; the concentration of the additive is 5-10mL/L; the temperature of the plating solution is 20-35 ℃; the silver plating current density of the conductive functional area is 100-150A/dm 2 The thickness of the silver plating layer of the conductive functional area is 1.5-4 mu m.
The additive is 2 (3, 4-dichlorobenzyl) benzimidazole: nicotinic acid and derivatives thereof: tween 40: sodium hydroxymethylene sulfonate (EHS): a mixture of potassium hydroxide in a mass ratio of 15-65:5-15:3-8:0.6-1.6:50-100.
The main function of the 2 (3, 4-dichlorobenzyl) benzimidazole, nicotinic acid and derivatives thereof in the additive is to increase the brightness of the coating; the tween 40 has the main function of improving the fine crystallization of the coating and expanding the range of a low current density area; the main function of sodium styryl sulfonate (EHS) is to adjust the surface tension of the plating solution; the main function of potassium hydroxide is to increase conductivity and stabilize the PH of the bath.
Further, the plating solution for plating silver on the conductive functional area also contains a brightening agent and an additive; the brightening agent is a mixture solution of pyridinium propane sulfonate, 1, 4-butynediol, nonionic surfactant and the like, and can improve the brightness of the silver plating layer; the additive comprises a running agent, a finishing agent and the like, and has the main functions of increasing the brightness of the low-current density area, refining crystal particles, improving the compactness of the crystals, improving the plating layer to be uniform and fine, and simultaneously increasing the stability of the plating solution (the finishing agent in the plating solution is a wetting agent and has the main functions of improving the surface tension of the plating solution and maintaining the stability of the plating solution).
Further, removing silver layer of non-conductive functional region of lead frame by electrolytic reaction, wherein the electrolyte contains 60-120g/L silver removing powder, the electrolytic temperature is 20-35deg.C, and the current density is 2-6A/dm 2 The electrolytic silver stripping time is 5-15 seconds.
Further, in the step 8, the plating solution for plating tin on the non-conductive functional area comprises methylsulfonic acid and methylsulfonic acid tin; the concentration of the methylsulfonic acid is 80-100g/L; the concentration of the tin methylsulfonate is 100-150g/L according to the tin content; the temperature of the plating solution is 20-30 ℃; the current density of the non-conductive functional area tinning is 2-6A/dm 2 The plating thickness of the non-conductive functional area tinning is 3-5 mu m.
In the step 1, the optocoupler lead frame further comprises the step of degreasing and activating before the bottoming and the nickel plating; the optocoupler lead frame is an iron-based optocoupler lead frame or a copper-based optocoupler lead frame;
in the step 8, the step of acid activation is further included before the tin plating of the non-conductive functional area, and the step of electroplating a tin protective layer is further included after the tin plating of the non-conductive functional area is completed;
in the step 1-8, the method further comprises the step of washing 3-5 times after each electroplating is completed; the water for the first flushing is recycled, the second/third flushing can be recycled, and the last flushing can be performed with pure RO deionized water, so that water resources can be saved.
Because the optocoupler lead frame is of a planar structure, different plating layers are difficult to plate on one plane in a region dividing way, the prior art generally comprises the steps of firstly electroplating silver layers on a conductive functional region, then delivering to a packaging factory to complete product such as surface mounting, bonding wires, dispensing, curing and packaging, delivering to an electroplating factory to tin the pins, and then testing and packaging in the packaging factory. The repeated reciprocating packaging factory and electroplating factory waste manpower and physics, and the construction period is prolonged. The technical difficulty that different plating layers are difficult to plate on a plane in a zoned manner is that the functional requirements of the electronic fitting are very precise, the original silver plating layer cannot be damaged when the electronic fitting is partially plated with silver after silver plating, and the tin plating liquid formula is reasonably configured to achieve the performance (oxidation resistance, high temperature resistance, electrical performance and the like) of the silver plating layer of the finished product, and the good solderability and high temperature resistance of the tin plating layer are considered. The invention designs the nickel sulfamate nickel plating layer under the silver plating layer, reduces internal stress, improves bonding force and high temperature resistance, and lays a solid foundation for the following electroplated layer. The silver plating additive enhances the oxidation resistance and high temperature resistance of the silver layer and avoids damaging the silver layer after tinning. The invention preferably tinning the tin methylsulfonate system, reduces the acidity of the tinning liquid, and avoids the damage of the strong acidity of the stannous sulfide tinning to the silver layer.
The invention discloses the following technical effects:
(1) According to the invention, the nickel sulfamate layer is plated between the copper plating layer and the silver plating layer and between the copper plating layer and the tin plating layer, so that the binding force between the copper plating layer and the silver plating layer and between the copper plating layer and the tin plating layer can be increased, the plating layer is not easy to fall off, and the high-temperature resistance stability of the plating layer is increased; the nickel sulfamate layer can also increase the plumpness of the coating, so that the coating is smooth and clean, and the quality of the coating is improved.
(2) According to the invention, silver plating on the conductive functional area and pin tin plating are completed before packaging, so that damage to an optocoupler product (such as potential corrosion of chemical liquid medicine to a packaged product) caused by secondary electroplated tin after packaging is avoided, the problem of low efficiency caused by repeated reciprocating packaging factories and electroplating factories is avoided, the packaging efficiency of the optocoupler lead frame product is greatly improved, the delivery period is shortened, and the labor cost and the time cost are saved. (3) The conductive functional area plating layer prepared by the method has good weldability and conductivity, and the non-conductive functional area plating layer has higher binding force, high temperature resistance and weldability.
(4) The invention adopts various electroplating processes to form the composite electroplated layer, can meet the collinear electroplating of the iron-based material and the copper-based material, improves the conductivity and the binding force of the electroplated layer, and has the characteristics of fine crystallization, low internal stress, good ductility and excellent soldering tin property.
(5) The silver-nickel-copper-nickel coating prepared by the method has excellent high temperature resistance, has no bubble under the baking condition of 300+/-10 ℃/5 minutes, even has no bubble under the short-time (5 s) baking condition of 350 ℃, and is obviously superior to the high temperature resistance of 260-270 ℃/5 minutes commonly in the prior art.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings can be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a physical photograph of a material strip to be plated (an iron-based optocoupler lead frame);
FIG. 2 is a plan view of a plating layer according to the present invention; in the figure, the A/B/F/G points are conductive functional areas, and the functional layers are silver layers; the D/I point is a non-conductive functional area, and the functional layer is a tin layer; the C/H point is only provided with a nickel-copper-nickel coating, which separates silver and tin connection and prevents tin from interfering the electrical performance of the silver layer due to tin whisker generated when the tin layer is placed for a long time; point E is the reference point for high temperature testing.
FIG. 3 is a schematic view showing the structure of a plating layer according to examples 1 to 3 of the present invention; in the figure, 1-a material belt (substrate) to be plated; a 2-nickel layer; a 3-copper layer; a 4-nickel layer; a 5-tin layer; 6-silver layer;
FIG. 4 is a flow chart of the plating process of the present invention.
Detailed Description
Various exemplary embodiments of the invention will now be described in detail, which should not be considered as limiting the invention, but rather as more detailed descriptions of certain aspects, features and embodiments of the invention.
It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In addition, for numerical ranges in this disclosure, it is understood that each intermediate value between the upper and lower limits of the ranges is also specifically disclosed. Every smaller range between any stated value or stated range, and any other stated value or intermediate value within the stated range, is also encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference for the purpose of disclosing and describing the methods and/or materials associated with the documents. In case of conflict with any incorporated document, the present specification will control.
It will be apparent to those skilled in the art that various modifications and variations can be made in the specific embodiments of the invention described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from consideration of the specification of the present invention. The specification and examples of the present invention are exemplary only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are intended to be inclusive and mean an inclusion, but not limited to.
In the embodiment of the invention, the lead frame is an iron-based optocoupler lead frame, and the copper-based lead frame is also applicable to the invention.
The raw materials used in the examples of the present invention, unless otherwise specified, were obtained from commercial sources.
A physical photograph of the material tape to be plated (the iron-based optocoupler lead frame) used in the embodiment of the invention is shown in FIG. 1.
The plane distribution diagram of the electroplated layer is shown in figure 2; in the figure, the A/B/F/G points are conductive functional areas, and the functional layers are silver layers; the D/I point is a non-conductive functional area, and the functional layer is a tin layer; the C/H point is only provided with a nickel-copper-nickel coating (the thickness of the nickel-copper-nickel coating of the copper conductive functional area and the non-conductive functional area) which separates silver and tin connection, so that tin whisker is prevented from interfering the electrical performance of the silver layer when the tin layer is placed for a long time; the E point is a reference point for high temperature test, the temperature measuring point in high temperature test is the E point, and A/B/C/D/F/G/H represents a reference point for measuring the thickness of the coating. The structure and thickness of the three layers of plating layers (nickel-copper-nickel plating layers) in front of the optocoupler lead frame are the same whether the optocoupler lead frame is a conductive functional area or a non-conductive functional area.
The schematic structure of the electroplated layer of the embodiment 1-3 of the invention is shown in FIG. 3; in the figure, 1-a material belt (substrate) to be plated; a 2-nickel layer; a 3-copper layer; a 4-nickel layer; a 5-tin layer; 6-silver layer.
The flow chart of the electroplating layer processing of the invention is shown in figure 4.
The additive in the plating solution used for the local silver plating in the embodiment of the invention is specifically 2 (3, 4-dichlorobenzyl) benzimidazole: nicotinic acid and derivatives thereof: tween 40: sodium hydroxymethylene sulfonate (EHS): a mixture of potassium hydroxide in a mass ratio of 24:11:5:1.2:58.8.
Example 1
Step 1, leading out a material belt to be plated from a discharging frame, passing through a high-temperature chemical ultrasonic groove along with a traction belt, emulsifying and removing greasy dirt on the surface of the material belt by using high-temperature degreasing liquid, and removing metal burrs and slag scraps attached during blanking of the material belt by using ultrasonic vibration. And then the material belt enters an electrolytic oil removing groove, and a large amount of oxygen is generated on the surface of the material belt by utilizing electrochemical reaction, so that putty on the surface of the material belt is further cleaned. And then cleaning for three times (three to five times) by using clean tap water for spray rinsing, and removing the surface electrolyte.
And 2, feeding the material belt into a sulfuric acid activation tank, removing an oxide layer on the surface of the material belt, and enhancing the binding force between the metal matrix and the priming nickel plating layer. And after the sulfuric acid activation is finished, the sulfuric acid is sprayed, washed and washed three times by RO deionized water, and sulfuric acid solution is removed.
Step 3, the material belt enters a priming nickel plating tank, the plating solution consists of 180g/L of nickel sulfate, 50g/L of nickel chloride, 50g/L of boric acid, 1.2mL/L of nickel plating main brightening agent and 120mL/L of nickel plating softener, the temperature is 60 ℃, the pH value is 4.2, the plating solution is continuously filtered and auxiliary circularly stirred, and the current density is 4A/dm 2 The thickness of the bottoming electroplated nickel layer is 1.5 mu m. And after the nickel plating is finished, spraying and washing four times by RO deionized water, and removing the nickel plating solution.
Step 4, the material belt enters a preplating alkaline copper tank, the plating solution consists of 30g/L of cuprous cyanide and 120g/L of sodium cyanide, the temperature is 40 ℃, the plating solution is continuously filtered and assisted and circularly stirred, and the current density is 7A/dm 2 The thickness of the preplated copper layer was 1.5. Mu.m. And then spraying and flushing with RO deionized water four times to thoroughly remove the alkaline copper plating solution.
Step 5, the material belt enters a copper sulfate bright acidic copper plating tank, the plating solution consists of 200g/L of copper sulfate, 35mL/L of sulfuric acid, 100mg/L of chloride ion, 6mL/L of acid copper cylinder opener and 0.6mL/L of brightening agent, the temperature is 25 ℃, the plating solution is continuously filtered and assisted and circularly stirred, and the current density is 6A/dm 2 The thickness of the bright electroplated copper layer was 2.5 μm. And then, spraying and flushing with RO deionized water for four times to thoroughly remove the residual plating solution.
Step 6, the material belt enters a nickel sulfamate plating tank, the plating solution consists of 80g/L of nickel sulfamate, 12g/L of nickel chloride, 45g/L of boric acid, 1.5mL/L of nickel plating main brightening agent and 100mL/L of nickel plating softener, the temperature is 63 ℃, the pH value is 4.2, the plating solution is continuously filtered and assisted and circularly stirred, and the current density is 5A/dm 2 The thickness of the electroplated nickel layer is 2 μm. And then spraying and flushing with RO deionized water four times to remove the nickel plating solution.
Step 7, the material belt enters a pre-silver plating tank, and the pre-silver plating solution is prepared from 100g/L of potassium cyanide and 8g/L of silver cyanide (containing silver)Composition, solution temperature 30 ℃, current density 5A/dm 2 A 0.3 μm silver layer was formed on the nickel layer. And then spraying and flushing with RO deionized water for three times to remove the plating solution.
Step 8, the material belt enters a local silver plating tank, passes through a rotating wheel die, shields a non-conductive functional area, continuously sprays plating solution, wherein the silver plating solution consists of 120g/L of potassium cyanide and 16g/L of silver cyanide (containing silver), 10mL/L of additive and 10mL/L of brightening agent, the solution temperature is 30 ℃, and the current density is 100A/dm 2 A 3 μm silver layer was formed on the pre-silver layer of the conductive functional region. And then spraying and flushing for five times by RO deionized water, and removing the plating solution to obtain the silver-nickel-copper-nickel plating layer.
And 9, feeding the material belt into an electrolytic stripping tank, stripping the thin silver layer of the non-conductive functional area of the lead frame through electrolytic reaction, and forming a nickel layer isolation belt between the silver plating area of the conductive functional area and the tin plating area of the non-conductive functional area to prevent the tin layer from generating fine whiskers during the placing process to influence the conductive performance of the silver layer. The electrolyte contains 100g/L silver-removing powder, the electrolysis temperature is 30 ℃, and the current density is 4A/dm 2 The electrolytic desilverization time was 15 seconds. And then the electrolytic solution is removed by spraying and flushing three times with RO deionized water.
Step 10, the material belt enters an acid activation tank, the acid activation solution contains 100g/L of methyl sulfonic acid, the activation temperature is 30 ℃, and the activation time is 15 seconds, (the purpose of activation is to eliminate oxides on a nickel layer and increase the binding force between a tin plating layer and the nickel layer). And then, washing for three times by using RO deionized water in a spraying way, and removing the activated acid solution.
Step 11, the material belt enters a tinning tank, a tinning solution consists of 100g/L of methylsulfonic acid and 120g/L of tin methylsulfonate, the temperature of the solution is 25 ℃, and the current density is 4A/dm 2 And a 7 mu m tin layer is formed on the nickel layer of the non-conductive functional area, so that good solderability can be provided for the packaged optocoupler pins. After tinning, the material strip needs to be sprayed and washed four times by RO deionized water, so that the residual plating solution is thoroughly removed. A tin-nickel-copper-nickel plating layer is obtained.
Step 12, the material belt enters a tin protection tank, a tin protection solution consists of 100g/L of a tin protective agent, the temperature of the solution is 25 ℃, and the current density is 4A/dm 2 Forming a 0.06 μm protective layer on the tin layer to obtain an optical coupler after encapsulationThe pins provide good shielding properties. And then, spraying, washing and cleaning for three times by using RO deionized water, and thoroughly removing residual protective liquid.
And 13, feeding the material belt into a dewatering tank, and blowing off water on the surface of the material belt by using oil-free and water-free air by using a blowing device.
And 14, the material belt passes through a hot air drying box, the drying temperature is 150 ℃, the time is 30 seconds, the surface of the material belt is thoroughly dried, and the material is received and packaged, so that the electroplating process is completed.
The plating prepared in the embodiment is subjected to a firm plating binding force test, and is bent for 90 degrees for 5 times under the test condition of 20 ℃ and relative humidity of 85 percent, the straight insert is twisted for 360 degrees for 5 circles, and the plating is free from falling off; 100% of the plating layer of the surface-mounted planar piece drawing method is free from falling off, and the requirement of the post-processing bending process of the product is met.
The silver-nickel-copper-nickel plating layer and the tin-nickel-copper-nickel plating layer prepared by the embodiment are smooth and clean and have good plumpness.
The silver-nickel-copper-nickel coating prepared by the embodiment has excellent high temperature resistance, no foaming at 350 ℃/5s under the high temperature baking test condition, and can meet the requirements of wire bonding and wave soldering; no foaming occurs at 300 ℃/5 minutes, and the requirements of welding wires and wave soldering can be met; the foaming is avoided at 175 ℃/3 hours and 150 ℃/8 hours, and the curing engineering requirement of the packaging process can be met.
The tin-nickel-copper-nickel plating layer prepared by the embodiment has no foaming and peeling at 200 ℃/10 minutes, and meets the tin-plating property and firmness of pin welding.
Example 2
Step 1, step 1 is the same as in example 1.
Step 2, the same as step 2 of example 1.
Step 3, the material belt enters a priming nickel plating tank, the plating solution consists of 170g/L of nickel sulfate, 48g/L of nickel chloride, 50g/L of boric acid, 0.8mL/L of nickel plating main brightening agent and 80mL/L of nickel plating softener, the temperature is 65 ℃, the pH value is 4.2, the plating solution is continuously filtered and auxiliary circularly stirred, and the current density is 4A/dm 2 The thickness of the bottoming electroplated nickel layer is 1 mu m. And after the nickel plating is finished, spraying and washing four times by RO deionized water, and removing the nickel plating solution.
Step 4, the material belt enters a preplating alkaline copper tank, and the plating solution is prepared from 25g of cuprous cyanideL and sodium cyanide 100g/L, the temperature is 40 ℃, the plating solution is continuously filtered and assisted in circulating stirring, and the current density is 4A/dm 2 The thickness of the preplated copper layer was 1.2. Mu.m. And then spraying and flushing with RO deionized water four times to thoroughly remove the alkaline copper plating solution.
Step 5, the material belt enters a copper sulfate bright acidic copper plating tank, the plating solution consists of 220g/L of copper sulfate, 40mL/L of sulfuric acid, 120mg/L of chloride ion, 6mL/L of acid copper cylinder opener and 0.5mL/L of brightening agent, the temperature is 28 ℃, the plating solution is continuously filtered and assisted and circularly stirred, and the current density is 5A/dm 2 The thickness of the bright electroplated copper layer was 4. Mu.m. And then, spraying and flushing with RO deionized water for four times to thoroughly remove the residual plating solution.
Step 6, the material belt enters a nickel sulfamate plating tank, the plating solution consists of 90g/L of nickel sulfamate, 15g/L of nickel chloride, 45g/L of boric acid, 0.8mL/L of nickel plating main brightening agent and 60mL/L of nickel plating softener, the temperature is 65 ℃, the pH value is 4.0, the plating solution is continuously filtered and auxiliary circularly stirred, and the current density is 3A/dm 2 The thickness of the electroplated nickel layer is 2 μm. And then spraying and flushing with RO deionized water four times to remove the nickel plating solution.
Step 7, the material belt enters a pre-silver plating tank, the pre-silver plating solution consists of 80g/L potassium cyanide and 5g/L silver cyanide (containing silver), the solution temperature is 35 ℃, and the current density is 4A/dm 2 A 0.2 μm silver layer was formed on the nickel layer. And then spraying and flushing with RO deionized water for three times to remove the plating solution.
Step 8, the material belt enters a local silver plating tank, passes through a rotating wheel die, shields a non-conductive functional area, continuously sprays plating solution, wherein the silver plating solution consists of 120g/L of potassium cyanide and 20g/L of silver cyanide (containing silver), 5mL/L of additive and 5mL/L of brightening agent, the solution temperature is 35 ℃, and the current density is 100A/dm 2 A 4 μm silver layer was formed on the pre-silver layer of the conductive functional region. And then spraying and flushing with RO deionized water for five times to remove the plating solution. A silver-nickel-copper-nickel plating layer is obtained.
Step 9, the material belt enters an electrolytic stripping tank, the silver layer of the non-conductive functional area of the lead frame is stripped through electrolytic reaction, the electrolyte contains 120g/L silver stripping powder, the electrolytic temperature is 30 ℃, and the current density is 6A/dm 2 Electrolytic desilverization time was 10 seconds. And then the electrolytic solution is removed by spraying and flushing three times with RO deionized water.
Step 10, the material belt enters an acid activation tank, the acid activation solution contains 120g/L of methyl sulfonic acid, the activation temperature is 25 ℃, and the activation time is 10 seconds, (the purpose of activation is to increase the binding force between a tinning layer and a nickel layer). And then, washing for three times by using RO deionized water in a spraying way, and removing the activated acid solution.
Step 11, the material belt enters a tinning tank, a tinning solution consists of 100g/L of methylsulfonic acid and 150g/L of tin methylsulfonate, the temperature of the solution is 26 ℃, and the current density is 5A/dm 2 And a 6 mu m tin layer is formed on the nickel layer of the non-conductive functional area, so that good solderability can be provided for the packaged optocoupler pins. After tinning, the material strip needs to be sprayed and washed four times by RO deionized water, so that the residual plating solution is thoroughly removed. A tin-nickel-copper-nickel plating layer is obtained.
Step 12, the material belt enters a tin protection tank, a tin protection solution consists of 120g/L of a tin protective agent, the temperature of the solution is 30 ℃, and the current density is 3A/dm 2 A0.1 mu m tin protective layer is formed on the tin layer, so that good protective performance can be provided for the packaged optocoupler pins. And then, spraying, washing and cleaning for three times by using RO deionized water, and thoroughly removing residual protective liquid.
Step 13, the same as step 13 of example 1.
And 14, the material belt passes through a hot air drying box, the drying temperature is 180 ℃, the time is 30 seconds, the surface of the material belt is thoroughly dried, and the material is received and packaged, so that the electroplating process is completed.
The plating prepared in the embodiment is subjected to a firm plating binding force test, and is bent for 90 degrees for 5 times under the test condition of 25 ℃ and relative humidity of 85 percent, the straight insert is twisted for 360 degrees for 5 circles, and the plating is free from falling off; 100% of the plating layer of the surface-mounted planar piece drawing method is free from falling off, and the requirement of the post-processing bending process of the product is met.
The silver-nickel-copper-nickel plating layer and the tin-nickel-copper-nickel plating layer prepared by the embodiment are smooth and clean and have good plumpness.
The silver-nickel-copper-nickel coating prepared by the embodiment has excellent high temperature resistance, no foaming at 350 ℃/5s under the high temperature baking test condition, and can meet the requirements of wire bonding and wave soldering; no foaming occurs at 300 ℃/5 minutes, and the requirements of welding wires and wave soldering can be met; the foaming is avoided at 175 ℃/3 hours and 150 ℃/8 hours, and the curing engineering requirement of the packaging process can be met.
The tin-nickel-copper-nickel plating layer prepared by the embodiment has no foaming and peeling at 200 ℃/10 minutes, and meets the tin-plating property and firmness of pin welding.
Example 3
Step 1, step 1 is the same as in example 1.
Step 2, the same as step 2 of example 1.
Step 3, the material belt enters a priming nickel plating tank, the plating solution consists of 160g/L of nickel sulfate, 45g/L of nickel chloride, 45g/L of boric acid, 1.0mL/L of nickel plating main brightening agent and 100mL/L of nickel plating softener, the temperature is 62 ℃, the pH value is 4.0, the plating solution is continuously filtered and auxiliary circularly stirred, and the current density is 4A/dm 2 The thickness of the bottoming electroplated nickel layer is 1 mu m. And after the nickel plating is finished, spraying and washing four times by RO deionized water, and removing the nickel plating solution.
Step 4, the material belt enters a preplating alkaline copper tank, the plating solution consists of 20g/L of cuprous cyanide and 100g/L of sodium cyanide, the temperature is 40 ℃, the plating solution is continuously filtered and assisted and circularly stirred, and the current density is 8A/dm 2 The thickness of the preplated copper layer was 1.5. Mu.m. And then spraying and flushing with RO deionized water four times to thoroughly remove the alkaline copper plating solution.
Step 5, the material belt enters a copper sulfate bright acidic copper plating tank, the plating solution consists of 200g/L of copper sulfate, 40mL/L of sulfuric acid, 90mg/L of chloride ion, 5mL/L of acid copper cylinder opener and 0.5mL/L of brightening agent, the temperature is 28 ℃, the plating solution is continuously filtered and assisted and circularly stirred, and the current density is 4A/dm 2 The thickness of the bright electroplated copper layer was 2.5 μm. And then, spraying and flushing with RO deionized water for four times to thoroughly remove the residual plating solution.
Step 6, the material belt enters a nickel sulfamate plating tank, the plating solution consists of 70g/L of nickel sulfamate, 12g/L of nickel chloride, 45g/L of boric acid, 1.5mL/L of nickel plating main brightening agent and 100mL/L of nickel plating softener, the temperature is 62 ℃, the pH value is 4.2, the plating solution is continuously filtered and assisted and circularly stirred, and the current density is 5A/dm 2 The thickness of the electroplated nickel layer is 1.6 μm. And then spraying and flushing with RO deionized water four times to remove the nickel plating solution.
Step 7, the material belt enters a pre-silver plating tank, the pre-silver plating solution consists of 80g/L of potassium cyanide and 8g/L of silver cyanide, the solution temperature is 28 ℃, and the current density is highDegree 6A/dm 2 A 0.25 μm silver layer was formed on the nickel layer. And then spraying and flushing with RO deionized water for three times to remove the plating solution.
Step 8, feeding the material belt into a local silver plating tank, matching with a special rotating wheel die, continuously spraying plating solution, wherein the silver plating solution consists of 100g/L of potassium cyanide, 18g/L of silver cyanide, 5mL/L of additive and brightening agent, the solution temperature is 25 ℃, and the current density is 4A/dm 2 A 3 μm silver layer was formed on the pre-silver layer of the conductive functional region. And then spraying and flushing with RO deionized water for five times to remove the plating solution. A silver-nickel-copper-nickel plating layer is obtained.
Step 9, the material belt enters an electrolytic stripping tank, the silver layer of the non-conductive functional area of the lead frame is stripped through electrolytic reaction, the electrolyte contains 80g/L silver stripping powder, the electrolytic temperature is 25 ℃, and the current density is 4A/dm 2 The electrolytic desilverization time was 15 seconds. And then the electrolytic solution is removed by spraying and flushing three times with RO deionized water.
Step 10, the material belt enters an acid activation tank, the acid activation solution contains 120g/L of methyl sulfonic acid, the activation temperature is 25 ℃, and the activation time is 15 seconds, (the purpose of activation is to increase the binding force between a tinning layer and a nickel layer). And then, washing for three times by using RO deionized water in a spraying way, and removing the activated acid solution.
Step 11, the material belt enters a tinning tank, a tinning solution consists of 100g/L of methylsulfonic acid and 120g/L of methylsulfonic acid tin, the temperature of the solution is 26 ℃, and the current density is 4A/dm 2 And a 5.5 mu m tin layer is formed on the nickel layer of the non-conductive functional area, so that good solderability can be provided for the packaged optocoupler pins. After tinning, the material strip needs to be sprayed and washed four times by RO deionized water, so that the residual plating solution is thoroughly removed. A tin-nickel-copper-nickel plating layer is obtained.
Step 12, the material belt enters a tin protection tank, a tin protection solution consists of 100g/L of a tin protective agent, the temperature of the solution is 25 ℃, and the current density is 4A/dm 2 A0.08 mu m tin protective layer is formed on the tin layer, so that good protective performance can be provided for the packaged optocoupler pins. And then, spraying, washing and cleaning for three times by using RO deionized water, and thoroughly removing residual protective liquid.
Step 13, the same as step 13 of example 1.
And 14, the material belt passes through a hot air drying box, the drying temperature is 160 ℃, the time is 30 seconds, the surface of the material belt is thoroughly dried, and the material is received and packaged, so that the electroplating process is completed.
The silver-nickel-copper-nickel plating layer and the tin-nickel-copper-nickel plating layer prepared by the embodiment are smooth and clean and have good plumpness.
The plating prepared in the embodiment is subjected to a firm plating binding force test, and is bent for 90 degrees for 5 times under the test conditions of 25 ℃ and relative humidity of 85-95%, the straight insert is twisted for 360 degrees for 5 circles, and the plating is free from falling off; 100% of the plating layer of the surface-mounted planar piece drawing method is free from falling off, and the requirement of the post-processing bending process of the product is met.
The silver-nickel-copper-nickel coating prepared by the embodiment has excellent high temperature resistance, no foaming at 350 ℃/5s under the high temperature baking test condition, and can meet the requirements of wire bonding and wave soldering; no foaming occurs at 300 ℃/5 minutes, and the requirements of welding wires and wave soldering can be met; the foaming is avoided at 175 ℃/3 hours and 150 ℃/8 hours, and the curing engineering requirement of the packaging process can be met.
The tin-nickel-copper-nickel plating layer prepared by the embodiment has no foaming and peeling at 200 ℃/10 minutes, and meets the tin-plating property and firmness of pin welding.
Comparative example 1
The only difference from example 1 is that step 6 was omitted.
The silver-copper-nickel plating layer, tin-copper-nickel plating layer prepared in this comparative example were inferior in flatness and fullness to those of example 1.
The plating prepared in this comparative example was subjected to a firm test of the binding force of the plating, and was bent at 90 ° for 5 times under the test conditions of 25 ℃ and relative humidity of 85-95%, the straight insert was twisted 360 ° for 5 turns, and cracks were locally generated in the plating; the plating layer of the surface-mounted planar piece falls off by 2% in the grid drawing method, and the requirement of post-process processing and bending processes of customer products is not met.
The silver-copper-nickel coating prepared in the comparative example has excellent high temperature resistance and foams at 350 ℃/5s under the high temperature baking test condition; foaming at 300 ℃/5 minutes; 175 ℃/3 hours without foaming; no foaming occurred at 150 ℃/8 hours.
The tin-copper-nickel plating layer prepared in the embodiment has a slight foaming phenomenon at 200 ℃/10 minutes, and does not meet the firmness of pin welding.
The electroplating process of the optocoupler lead frame (the preparation method of the multifunctional composite electroplated layer of the optocoupler lead frame) is suitable for the iron-based optocoupler lead frame and the copper-based optocoupler lead frame, and the thickness of the electroplating layer can be adjusted according to the increase and decrease of electroplating procedures (the electroplating layer comprises but is not limited to nickel-copper-nickel-silver/tin combination) of the product characteristics. Such modifications are intended to fall within the scope of the invention as defined in the appended claims without undue burden to those skilled in the art.
The above embodiments are only illustrative of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention, and various modifications and improvements made by those skilled in the art to the technical solutions of the present invention should fall within the protection scope defined by the claims of the present invention without departing from the design spirit of the present invention.
Claims (8)
1. The multifunctional composite electroplated layer of the optocoupler lead frame is characterized by sequentially comprising a nickel layer, a copper layer, a nickel layer and a functional layer according to the direction of a substrate layer to the surface of the electroplated layer, wherein the functional layer of a conductive functional area of the optocoupler lead frame is a silver layer, and the functional layer of a non-conductive functional area of the optocoupler lead frame is a tin layer;
the preparation method of the multifunctional composite electroplated layer of the coupled lead frame comprises the following steps:
step 1, priming nickel plating is carried out on an optocoupler lead frame to obtain an optocoupler lead frame with a plated priming nickel layer;
step 2, pre-plating alkaline copper on the optocoupler lead frame plated with the bottoming nickel layer to obtain the pre-plated alkaline copper optocoupler lead frame;
step 3, carrying out acid copper plating on the pre-plated alkaline copper optocoupler lead frame to obtain an electroplated copper optocoupler lead frame;
step 4, nickel plating is carried out on the optocoupler lead frame with the electroplated copper layer, so that the optocoupler lead frame with the electroplated nickel layer is obtained; the nickel plating solution comprises 60-90g/L of nickel sulfamate, 8-15g/L of nickel chloride, 40-50g/L of boric acid, 0.5-2mL/L of nickel plating main brightening agent and 60-120mL/L of nickel plating softener according to the concentration;
step 5, pre-plating silver on the photo-coupler lead frame with the electroplated nickel layer to obtain a pre-plated photo-coupler lead frame;
step 6, silver plating is carried out on the conductive functional area of the pre-silver plated optocoupler lead frame, and an electroplated silver optocoupler lead frame is obtained;
step 7, carrying out desilvering treatment on the non-conductive functional area of the electroplated optical coupler lead frame to obtain a desilvered optical coupler lead frame;
step 8, tin plating is carried out on the non-conductive functional area of the optical coupler lead frame subjected to silver removal treatment, and the optical coupler lead frame with the multifunctional composite electroplated layer is obtained;
the silver removing treatment in the step 7 is electrolytic reaction to remove the thin silver layer of the non-conductive functional area in the lead frame, and a nickel layer isolation belt is formed between the silver plating area of the conductive functional area and the tin plating area of the non-conductive functional area;
in the step 1, according to the concentration, the plating solution for priming nickel plating comprises 150-180g/L of nickel sulfate, 45-50g/L of nickel chloride, 45-50g/L of boric acid, 0.5-2mL/L of nickel plating main brightening agent and 60-120mL/L of nickel plating softener; the temperature of plating solution for priming nickel plating is 55-65 ℃ and the pH value is 3.8-4.4; the current density of the priming nickel plating is 2-6A/dm 2 The thickness of the plating layer of the priming nickel plating is 1-3 mu m.
2. The multifunctional composite electroplated layer of the optocoupler lead frame according to claim 1, wherein in the step 2, the plating solution of the preplating alkaline copper comprises 15-30g/L of cuprous cyanide and 80-120g/L of sodium cyanide according to concentration; the plating solution temperature of the preplating alkaline copper is 35-45 ℃; the current density of the preplating alkaline copper is 4-10A/dm 2 The thickness of the preplating alkaline copper coating is 1-3 mu m.
3. The multifunctional composite electroplated layer of the optocoupler lead frame according to claim 1, wherein in the step 3, the plating solution of the acid copper plating comprises 180-220g/L of copper sulfate, 30-40mL/L of sulfuric acid, 80-120mg/L of chloride ions, 5-8mL/L of acid copper cylinder opener and 0.4-0.8mL/L of brightening agent according to concentration; the temperature of the plating solution for acidic copper plating is 22-28 ℃; the current density of the acid copper plating is 2-6A/dm 2 Plating thickness of acid copper platingThe degree is 2-5 μm.
4. The multifunctional composite electroplated layer of an optocoupler lead frame according to claim 1, wherein in step 4, the plating solution temperature of the nickel plating is 60-65 ℃, the pH value is 3.8-4.4, and the current density of the nickel plating is 2-6A/dm 2 The thickness of the nickel plating layer is 1-3 mu m.
5. The multifunctional composite electroplated layer of the optocoupler lead frame according to claim 1, wherein in the step 5, the plating solution of the pre-silver plating contains potassium cyanide and silver cyanide; the concentration of the potassium cyanide is 80-120g/L; the concentration of the silver cyanide in the plating solution is 4-8g/L according to silver ions; the current density of the pre-silver plating is 2-6A/dm 2 The thickness of the plating layer of the pre-silver plating is 0.1-0.2 mu m.
6. The multifunctional composite plating layer of an optocoupler lead frame of claim 1, wherein in step 6, the plating solution for plating silver on the conductive functional areas comprises potassium cyanide, silver cyanide and additives; the concentration of the potassium cyanide is 80-120g/L; the concentration of the silver cyanide is 10-20g/L according to silver ions; the concentration of the additive is 5-10mL/L; the silver plating current density of the conductive functional area is 100-150A/dm 2 The thickness of the silver plating layer of the conductive functional area is 1.5-4 mu m.
7. The multifunctional composite plating layer of an optocoupler lead frame according to claim 1, wherein in step 8, the plating solution for plating tin on the non-conductive functional region comprises methylsulfonic acid and methylsulfonic acid tin; the concentration of the methylsulfonic acid is 80-100g/L; the concentration of the tin methylsulfonate is 100-150g/L according to the tin content; the current density of the non-conductive functional area tinning is 2-6A/dm 2 The plating thickness of the non-conductive functional area tinning is 3-5 mu m.
8. The multifunctional composite electroplated layer of the optocoupler lead frame according to claim 1, wherein in the step 1, the optocoupler lead frame further comprises the steps of degreasing and activating before being subjected to bottoming and nickel plating; the optocoupler lead frame is an iron-based optocoupler lead frame or a copper-based optocoupler lead frame;
in the step 8, the step of acid activation is further included before the tin plating of the non-conductive functional area, and the step of electroplating a tin protective layer is further included after the tin plating of the non-conductive functional area is completed;
in the step 1-8, the method further comprises the step of washing 3-5 times after each electroplating is completed.
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Inventor after: Zhang Limin Inventor after: Han Hongliang Inventor after: Luo Pei Inventor after: Liu Zhongli Inventor after: Xiang Fujiu Inventor after: Zhang Jinping Inventor before: Zhang Limin Inventor before: Wang Ailiang Inventor before: Han Hongliang Inventor before: Luo Pei Inventor before: Liu Zhongli Inventor before: Xiang Fujiu Inventor before: Zhang Jinping |
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Denomination of invention: A multifunctional composite electroplating layer and preparation method for optocoupler lead frame Granted publication date: 20231107 Pledgee: Guangdong Huaxing Bank Co.,Ltd. Jiangmen Branch Pledgor: DINGXIANG (JIANGMEN) ELECTRONIC TECHNOLOGY Co.,Ltd. Registration number: Y2024980033297 |