CN115747907A - Multifunctional composite electroplated layer of optical coupling lead frame and preparation method - Google Patents
Multifunctional composite electroplated layer of optical coupling lead frame and preparation method Download PDFInfo
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- CN115747907A CN115747907A CN202211603089.1A CN202211603089A CN115747907A CN 115747907 A CN115747907 A CN 115747907A CN 202211603089 A CN202211603089 A CN 202211603089A CN 115747907 A CN115747907 A CN 115747907A
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- 230000008878 coupling Effects 0.000 title claims abstract description 34
- 238000010168 coupling process Methods 0.000 title claims abstract description 34
- 238000005859 coupling reaction Methods 0.000 title claims abstract description 34
- 239000002131 composite material Substances 0.000 title claims abstract description 13
- 238000002360 preparation method Methods 0.000 title claims abstract description 11
- 238000007747 plating Methods 0.000 claims abstract description 308
- 239000010410 layer Substances 0.000 claims abstract description 229
- 229910052709 silver Inorganic materials 0.000 claims abstract description 86
- 239000004332 silver Substances 0.000 claims abstract description 86
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 83
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 claims abstract description 72
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims abstract description 68
- 239000010949 copper Substances 0.000 claims abstract description 68
- 229910052802 copper Inorganic materials 0.000 claims abstract description 68
- 238000009713 electroplating Methods 0.000 claims abstract description 21
- 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 16
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 190
- 229910052759 nickel Inorganic materials 0.000 claims description 95
- 238000000034 method Methods 0.000 claims description 33
- 239000002253 acid Substances 0.000 claims description 28
- 238000000576 coating method Methods 0.000 claims description 21
- AFVFQIVMOAPDHO-UHFFFAOYSA-N Methanesulfonic acid Chemical compound CS(O)(=O)=O AFVFQIVMOAPDHO-UHFFFAOYSA-N 0.000 claims description 20
- 230000004913 activation Effects 0.000 claims description 20
- 239000003795 chemical substances by application Substances 0.000 claims description 20
- 239000011248 coating agent Substances 0.000 claims description 19
- 230000037452 priming Effects 0.000 claims description 18
- 239000003513 alkali Substances 0.000 claims description 17
- 238000005406 washing Methods 0.000 claims description 17
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 16
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 14
- 239000000654 additive Substances 0.000 claims description 14
- 230000000996 additive effect Effects 0.000 claims description 14
- 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
- 238000005282 brightening Methods 0.000 claims description 12
- 229910021586 Nickel(II) chloride Inorganic materials 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
- QMMRZOWCJAIUJA-UHFFFAOYSA-L nickel dichloride Chemical compound Cl[Ni]Cl QMMRZOWCJAIUJA-UHFFFAOYSA-L 0.000 claims description 11
- 229940098779 methanesulfonic acid Drugs 0.000 claims description 10
- 239000004902 Softening Agent Substances 0.000 claims description 9
- 239000002585 base Substances 0.000 claims description 8
- 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 7
- 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 6
- 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
- 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
- DOBRDRYODQBAMW-UHFFFAOYSA-N copper(i) cyanide Chemical compound [Cu+].N#[C-] DOBRDRYODQBAMW-UHFFFAOYSA-N 0.000 claims description 5
- 239000011241 protective layer Substances 0.000 claims description 5
- 238000005238 degreasing Methods 0.000 claims description 3
- 230000003213 activating effect Effects 0.000 claims description 2
- PGGZKNHTKRUCJS-UHFFFAOYSA-N methanesulfonic acid;tin Chemical compound [Sn].CS(O)(=O)=O PGGZKNHTKRUCJS-UHFFFAOYSA-N 0.000 claims description 2
- 230000002378 acidificating effect Effects 0.000 claims 1
- 238000004806 packaging method and process Methods 0.000 abstract description 22
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- 229910021641 deionized water Inorganic materials 0.000 description 32
- 238000012360 testing method Methods 0.000 description 18
- 230000008569 process Effects 0.000 description 14
- UJAXHWXDLUXGII-UHFFFAOYSA-N [Ni].[Cu].[Ag].[Ni] Chemical compound [Ni].[Cu].[Ag].[Ni] UJAXHWXDLUXGII-UHFFFAOYSA-N 0.000 description 11
- 239000007921 spray Substances 0.000 description 11
- 238000005507 spraying Methods 0.000 description 11
- 238000003466 welding Methods 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
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- 238000005452 bending Methods 0.000 description 5
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- PVNIIMVLHYAWGP-UHFFFAOYSA-N Niacin Chemical compound OC(=O)C1=CC=CN=C1 PVNIIMVLHYAWGP-UHFFFAOYSA-N 0.000 description 4
- 230000005587 bubbling Effects 0.000 description 4
- 238000006243 chemical reaction 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
- 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
- 239000011247 coating layer Substances 0.000 description 3
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- QCEUXSAXTBNJGO-UHFFFAOYSA-N [Ag].[Sn] Chemical compound [Ag].[Sn] QCEUXSAXTBNJGO-UHFFFAOYSA-N 0.000 description 2
- 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
- 239000013078 crystal Substances 0.000 description 2
- 230000000670 limiting effect Effects 0.000 description 2
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- 229910052751 metal Inorganic materials 0.000 description 2
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- 229960003512 nicotinic acid Drugs 0.000 description 2
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- 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
- YMPYFFXCTQBDLV-UHFFFAOYSA-F [Sn+4].[Sn+4].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O Chemical compound [Sn+4].[Sn+4].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O YMPYFFXCTQBDLV-UHFFFAOYSA-F 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000007664 blowing Methods 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
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- 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
- 229910052760 oxygen Inorganic materials 0.000 description 1
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- 229940083256 peripheral vasodilators nicotinic acid and derivative Drugs 0.000 description 1
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- 238000012545 processing Methods 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
- 238000007670 refining Methods 0.000 description 1
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- 239000002893 slag Substances 0.000 description 1
- UNCPEAUIVGCHJJ-UHFFFAOYSA-M sodium;2-sulfoethenolate Chemical compound [Na+].OS(=O)(=O)C=C[O-] UNCPEAUIVGCHJJ-UHFFFAOYSA-M 0.000 description 1
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- 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 optical coupling lead frame and a preparation method thereof, and relates to the technical field of electroplated layers of optical coupling lead frames. The functional layer of the conductive functional area of the optical coupling lead frame is a silver layer, and the functional layer of the non-conductive functional area of the optical coupling lead frame is a tin layer. 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. The invention finishes silver plating of the conductive functional area and tin plating of the pins before packaging, avoids the damage of secondary tin plating to the optical coupling product after packaging, also avoids the problem of low efficiency caused by repeatedly returning to a packaging factory and an electroplating factory, shortens the delivery period, and saves labor and time cost.
Description
Technical Field
The invention relates to the technical field of electroplated layers of optical coupling lead frames, in particular to a multifunctional composite electroplated layer of an optical coupling lead frame and a preparation method thereof.
Background
The existing electroplating process of the optocoupler lead frame generally comprises a pretreatment process (electrolytic degreasing and activation) and nickel and silver plating; because the lead frame base material is developed from a copper base to an iron base material, the surface of the base material is smooth and uneven, the types of the plating layers are few, the surface brightness is low, the cost is increased by increasing the thickness of the nickel plating layer, the weldability is influenced, and the lead frame base material is difficult to adapt to the quality requirement of high-end electronic products.
The lead frame is delivered to a packaging factory after silver plating, products such as chip mounting, wire bonding, dispensing, curing packaging and the like are completed, then delivered to an electroplating factory for tin plating of the pins, and then returned to the packaging factory for testing, so that the production efficiency is reduced by two times of round trip, the delivery period is prolonged, and potential damage is generated to the optical coupling products 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, which are used for solving the problems in the prior art. The coating prepared by the invention is full and smooth, and meets the quality requirement of high-end electronic products; silver plating and tin plating of pins are completed before packaging, damage to the optical coupling product in the process of electroplating after packaging is avoided, and the problem of low efficiency caused by repeated package factory and electroplating factory is also avoided.
In order to achieve the purpose, the invention provides the following scheme:
according to the technical scheme, a multifunctional composite electroplated layer of the optocoupler lead frame sequentially comprises a nickel layer, a copper layer, a nickel layer and a functional layer in the direction from a base 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.
Furthermore, a nickel layer with the thickness of 1-3 μm, a copper layer with the thickness of 3-8 μm, a nickel layer with the thickness of 1-3 μm and a functional layer with the thickness of 1.6-8 μm are sequentially arranged in the direction from the substrate layer to the surface of the electroplating layer; when the functional layer is a silver layer, the thickness of the functional layer is 1.6-5 μm; when the functional layer is a tin layer, the functional layer has a thickness of 5 to 8 μm.
In the second technical scheme of the invention, the preparation method of the multifunctional composite electroplated layer of the optical coupling lead frame comprises the following steps:
step 7, performing silver stripping treatment on the non-conductive functional area of the silvered optocoupler lead frame (silver stripping treatment is performed on pre-silvered areas) to obtain the silvered optocoupler lead frame;
and 8, carrying out tin plating on the non-conductive functional area of the optical coupling lead frame subjected to the silver stripping treatment to obtain the optical coupling lead frame with the multifunctional composite electroplated layer.
In the step 4, the nickel sulfamate is adopted because 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 plumpness 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 coating layers can be increased, so that the coating layers are not easy to fall off, and the high-temperature resistance stability of the coating layers is improved. If nickel sulfate commonly used in the field is used for replacing nickel sulfamate in the step, the stress of the plating layer is large, the flexibility is insufficient, and the bonding force between the plating layers and the high-temperature resistance stability are influenced.
In the step 4, the concentration of nickel sulfamate of 60-90g/L, nickel chloride of 8-15g/L and boric acid of 40-50g/L in each component of the plating solution is determined through repeated tests, the concentration of each component is higher, the crystallization speed of the middle nickel plating layer is accelerated, the particles are rough, the stress is increased, the flexibility is deteriorated, the stability of the silver layer is influenced, the loss of nickel salt in the plating solution is increased along with the plated product, waste is caused, the concentration is low, the plating layer is thinner, the plating time is increased when the same thickness is reached, and an electroplated layer cannot be formed when the plating layer is too low.
Further, in the step 1, 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 main brightening agent for nickel plating and 60-120mL/L of softening agent for nickel plating according to concentration; 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 μm.
Further, in the step 2, the plating solution of the pre-plated alkali copper comprises 15-30g/L of cuprous cyanide and 80-120g/L of sodium cyanide according to concentration; the temperature of the plating solution for pre-plating the alkali copper is 35-45 ℃; the current density of the pre-plated alkali copper is 4-10A/dm 2 The thickness of the plating layer of the pre-plated alkali copper is 1-3 mu m.
Further, in the step 3, the plating solution for 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 a copper acid cylinder opening agent and 0.4-0.8mL/L of a brightening agent (A) by concentration; the temperature of the plating solution for acid copper plating is 22-28 ℃; the current density of the acid copper plating is 2-6A/dm 2 The thickness of the plating layer of the acid copper plating is 2-5 mu m.
Further, in step 4, the plating solution temperature of the nickel platingThe temperature 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 plating layer of the nickel plating is 1-3 μm.
Further, in step 5, the plating solution for pre-plating silver 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 calculated by silver ions; the temperature of the plating solution for pre-plating silver is 20-35 ℃; the current density of the pre-silvering is 2-6A/dm 2 The thickness of the pre-silvered coating is 0.1-0.2 μm.
Further, in step 6, the plating solution for silver plating of the conductive functional region comprises potassium cyanide, silver cyanide and an additive; the concentration of the potassium cyanide is 80-120g/L; the concentration of the silver cyanide is 10-20g/L calculated by silver ions; the concentration of the additive is 5-10mL/L; the temperature of the plating solution is 20-35 ℃; the current density of silver plating 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 its derivatives: tween 40: sodium hydroxyethenesulfonate (EHS): 15-65 of potassium hydroxide, 5-15 of.
The 2 (3, 4-dichlorobenzyl) benzimidazole, the nicotinic acid and the derivatives thereof in the additive are used together, and the main function is to increase the brightness of the coating; the main function of the Tween 40 is to improve the fine crystallization of the plating layer and expand the range of a low current density area; the main function of the sodium hydroxyvinylsulfonate (EHS) is to adjust the surface tension of the plating solution; the main functions of potassium hydroxide are to increase conductivity and stabilize the PH of the bath.
Further, the plating solution for silver plating of the conductive functional area also contains a brightener and an additive; the brightening agent is a mixture solution of pyridinium propanesulfonate, 1, 4-butynediol, a nonionic surfactant and the like, and can improve the brightness of the silver coating; the additive comprises a displacement agent, a finishing agent and the like, and the additive mainly has the functions of increasing the brightness of a low current density area, refining crystal particles, improving the compactness of crystals, improving a coating to be uniform and fine, and simultaneously increasing the stability of a plating solution (the finishing agent in the plating solution is a wetting agent and mainly has the functions of improving the surface tension of the plating solution and maintaining the stability of the plating solution).
Further, stripping the silver layer in the non-conductive functional area of the lead frame through an electrolytic reaction, wherein the electrolyte contains 60-120g/L stripped silver powder, the electrolytic temperature is 20-35 ℃, and the current density is 2-6A/dm 2 And the time for electrolytic silver stripping is 5-15 seconds.
Further, in step 8, the plating solution for plating the non-conductive functional region with tin comprises methanesulfonic acid and tin methylsulfonate; the concentration of the methanesulfonic acid is 80-100g/L; the concentration of the tin methane sulfonate is 100-150g/L according to the content of tin; the temperature of the plating solution is 20-30 ℃; the current density of the tin plating of the non-conductive functional area is 2-6A/dm 2 The thickness of the tin plating layer of the non-conductive functional area is 3-5 mu m.
Further, in the step 1, before priming nickel plating, the method also comprises the steps of degreasing and activating; the optical coupler lead frame is an iron-based optical coupler lead frame or a copper-based optical coupler lead frame;
in step 8, the step of acid activation is also included before the non-conductive functional region is tinned, and the step of electroplating a tin protective layer is also included after the non-conductive functional region is tinned;
in the steps 1-8, after each electroplating is finished, the step of washing for 3-5 times is also included; the water that washes for the first time is recycled, and the second/cubic sparge water can adopt the circulating water, and the last time is washed with pure RO deionized water, can the water economy resource.
Because the lead frame of the optical coupler is of a plane structure, different coatings are difficult to electroplate on a plane in different areas, in the prior art, a silver layer is generally electroplated in a conductive function area, then the silver layer is delivered to a packaging factory for pasting, welding wires, dispensing, curing and packaging and the like to complete products, then the products are delivered to the packaging factory for tinning pins, and then the products are tested in the packaging factory for packaging. The labor and the physical waste of the packaging factory and the electroplating factory are caused by repeated round trip, and the construction period is prolonged. The technical difficulty that different coatings are difficult to be electroplated on a plane in different areas is that the functional requirements of electronic accessories are very precise, the original silver coating cannot be damaged when the tin is partially plated after the silver is plated, the silver coating performance (oxidation resistance, high temperature resistance, electrical performance and the like) of a finished product can be achieved only by reasonably configuring the formula of a tinning solution, and the good weldability and high temperature resistance of the tin coating are considered. The nickel sulfamate nickel plating layer is designed under the silver plating layer, so that the internal stress is reduced, the binding force and the high temperature resistance are improved, and a solid foundation is laid for a subsequent electroplated layer. The silver plating additive enhances the oxidation resistance and high temperature resistance of the silver layer and avoids the silver layer from being damaged after tinning. The invention prefers tin methanesulfonate system to plate tin, reduces the acidity of tin plating solution and avoids the damage of strong acidity of tin-sulfate tin plating to a 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 plating layer, so that the plating layer is smooth and clean, and the quality of the plating layer is improved.
(2) The invention finishes silver plating on the conductive functional area and tin plating on the pins before packaging, thereby not only avoiding the damage of secondary tin plating on the optocoupler product after packaging (such as potential corrosion of chemical liquid on the packaged product), but also avoiding the problem of low efficiency caused by repeated round trip of a packaging factory and an electroplating factory, greatly improving the packaging efficiency of the optocoupler lead frame product, shortening delivery period, and saving labor and time cost. (3) The coating of the conductive functional region prepared by the invention has good weldability and conductivity, and the coating of the non-conductive functional region 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 iron-based materials and copper-based materials, improves the conductivity and the bonding force of the electroplated layer, and has the characteristics of fine crystallization, low internal stress, good ductility and excellent tin soldering property.
(5) The silver-nickel-copper-nickel plating layer prepared by the invention has excellent high temperature resistance, does not bubble under the baking condition of 300 +/-10 ℃/5 minutes, even does not 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 used 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 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 it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a photograph of a material strip to be plated (iron-based material opto-coupler lead frame);
FIG. 2 is a plan view of the plating layer of the present invention; in the figure, A/B/F/G points are conductive functional areas, and a functional layer is a silver layer; the D/I point is a non-conductive functional area, and the functional layer is a tin layer; the C/H point only has a nickel-copper-nickel coating, silver-tin connection is separated, and the tin layer is prevented from generating tin after being placed for a long time and interfering the electrical performance of the silver layer; point E is the high temperature test reference point.
FIG. 3 is a schematic diagram of a plating layer structure according to examples 1 to 3 of the present invention; in the figure, 1-strip (substrate) to be plated; 2-a nickel layer; 3-a copper layer; 4-a nickel layer; 5-a tin layer; 6-silver layer;
FIG. 4 is a flow chart of the electroplating layer process of the present invention.
Detailed Description
Reference will now be made in detail to various exemplary embodiments of the invention, the detailed description should not be construed as limiting the invention but as a more detailed description 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. Further, for numerical ranges in this disclosure, it is understood that each intervening value, between the upper and lower limit of that range, is also specifically disclosed. Every smaller range between any stated value or intervening value in a stated range and any other stated or intervening value in that stated range is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included or excluded in the range.
Unless defined otherwise, 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 herein 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 present disclosure without departing from the scope or spirit of the disclosure. Other embodiments will be apparent to those skilled in the art from consideration of the specification. The description and examples are intended to be illustrative only.
As used herein, the terms "comprising," "including," "having," "containing," and the like are open-ended terms that mean including, but not limited to.
The lead frame is an iron-based optical coupler lead frame, and the copper-based optical coupler lead frame is also applicable to the invention.
The starting materials used in the examples of the present invention were obtained from commercial sources unless otherwise specified.
A physical photograph of a strip of material to be plated (iron-based opto-coupler lead frame) used in an embodiment of the present invention is shown in fig. 1.
The plan distribution of the electroplated layer of the invention is shown in FIG. 2; in the figure, the A/B/F/G point is a conductive functional area, and the functional layer is a silver layer; the D/I point is a non-conductive functional area, and the functional layer is a tin layer; C/H point only has nickel-copper-nickel coating (coating thickness copper conductive functional area and nickel-copper-nickel coating thickness of non-conductive functional area), separate silver tin connection, prevent tin layer from standing for a long time and producing tin and must interfere silver layer electrical property; the point E is a high-temperature test reference point, the temperature measuring point during the high-temperature test is at the point E, and A/B/C/D/F/G/H represents a plating layer thickness measuring reference point. The structure and the thickness of the front three layers of plating layers (nickel-copper-nickel plating layers) are the same no matter the optical coupling lead frame is a conductive functional area or a non-conductive functional area.
The plating layer structure of the embodiments 1-3 of the invention is schematically shown in FIG. 3; in the figure, 1-strip (substrate) to be plated; 2-a nickel layer; 3-a copper layer; 4-a nickel layer; 5-a tin layer; 6-silver layer.
The processing flow chart of the electroplated layer of the invention is shown in figure 4.
The additive in the plating solution used for the partial silver plating in the embodiment of the invention is specifically 2 (3, 4-dichlorobenzyl) benzimidazole: nicotinic acid and derivatives thereof: tween 40: sodium hydroxyethenesulfonate (EHS): potassium hydroxide mass ratio 24.
Example 1
And 2, enabling the material belt to enter a sulfuric acid activation tank, removing an oxide layer on the surface of the material belt, and enhancing the bonding force between the metal matrix and the priming nickel plating layer. After the activation of the sulfuric acid is finished, the sulfuric acid solution is removed by spraying, washing and cleaning for three times by using RO deionized water.
Step 7, the material belt enters a pre-silver plating tank, the pre-silver plating solution consists of 100g/L potassium cyanide and 8g/L silver cyanide, the temperature of the solution is 30 ℃, and the current density is 5A/dm 2 And forming a silver layer of 0.3 μm on the nickel layer. And then spray-washing 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, and continuously sprays plating solution, wherein the silver plating solution consists of 120g/L potassium cyanide and 16g/L silver cyanide, the additive is 10mL/L and the brightener is 10mL/L, the solution temperature is 30 ℃, and the current density is 100A/dm 2 And forming a silver layer with the thickness of 3 mu m on the pre-plated silver layer of the conductive functional area. And then, carrying out spray rinsing for five times by using 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 off the thin silver layer in the non-conductive functional area of the lead frame through electrolytic reaction, and forming a nickel layer isolation belt between the silver plating area in the conductive functional area and the tin plating area in the non-conductive functional area to prevent the tin layer from generating fine whiskers to influence the conductivity of the silver layer during placement. The electrolyte contains 100g/L silver stripping powder, the electrolysis temperature is 30 ℃, and the current density is 4A/dm 2 And the time for electrolytic silver stripping is 15 seconds. And then spray rinsing with RO deionized water for three times to remove the electrolytic solution.
And step 10, allowing the material belt to enter an acid activation tank, wherein an acid activation solution contains 100g/L of methanesulfonic 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 bonding force between a tin plating layer and the nickel layer). And then spray-washing and cleaning with RO deionized water for three times to remove the activated acid solution.
Step 11, the material belt enters a tin plating tank, a tin plating solution consists of 100g/L methanesulfonic acid and 120g/L methanesulfonic acid tin (containing tin), the solution temperature is 25 ℃, and the current density is 4A/dm 2 And a 7-micron tin layer is formed on the nickel layer of the non-conductive functional area, so that good weldability can be provided for the packaged optocoupler pin. After tinning, the material belt needs to be sprayed and washed by RO deionized water for four times, so that the residual plating solution is thoroughly removed. And obtaining the tin-nickel-copper-nickel plating layer.
Step 12, the material belt enters a tin protective tank, tin protective solution consists of 100g/L tin protective agent, the temperature of the solution is 25 ℃, and the current density is 4A/dm 2 And a 0.06-micron protective layer is formed on the tin layer, so that good protection performance can be provided for the packaged optical coupler pin. And then, spraying, washing and cleaning the substrate for three times by using RO deionized water to thoroughly remove the residual protective solution.
And step 13, the material belt enters a dewatering tank, and the air blowing device blows water on the surface of the material belt by using oil-free and water-free air.
And step 14, passing the material belt through a hot air drying box, drying at the temperature of 150 ℃ for 30 seconds, completely drying the surface of the material belt, receiving materials, packaging and finishing the electroplating process.
The plating layer prepared in the embodiment is subjected to a plating layer binding force firmness test, the plating layer is bent for 5 times at 90 degrees under the test conditions of 20 ℃ and 85% of relative humidity, a straight plug-in unit is twisted for 5 circles at 360 degrees, and the plating layer does not fall off; the plating layer of the surface mount device plane piece by the grid drawing method has 100 percent of no falling, and meets the requirements of post-processing and bending procedures of products.
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 plating layer prepared by the embodiment has excellent high temperature resistance, does not generate bubbles at 350 ℃/5s under the high-temperature baking test condition, and can meet the requirements of welding wires and wave soldering; no bubble at 300 ℃/5 minutes, can meet the requirements of welding wire and wave soldering; no foaming at 175 deg.C/3 hr and 150 deg.C/8 hr, and can meet the curing engineering requirement of the package process.
The tin-nickel-copper-nickel plating layer prepared by the embodiment has no bubbling and peeling at 200 ℃/10 minutes, and meets the easy tin feeding property and firmness of pin welding.
Example 2
Step 7, the material belt enters a pre-silver plating groove, the pre-silver plating solution consists of 80g/L potassium cyanide and 5g/L silver cyanide,the solution temperature is 35 ℃, and the current density is 4A/dm 2 And forming a 0.2 mu m silver layer on the nickel layer. And then, carrying out spray rinsing for three times by using RO deionized water 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, and continuously sprays plating solution, wherein the silver plating solution consists of 120g/L potassium cyanide and 20g/L silver cyanide, 5mL/L additive and 5mL/L brightener, the solution temperature is 35 ℃, and the current density is 100A/dm 2 And forming a silver layer with the thickness of 4 mu m on the pre-plated silver layer of the conductive functional area. And then the plating solution is removed by spraying and washing the solution for five times by RO deionized water. Thus obtaining the silver-nickel-copper-nickel plating layer.
Step 9, the material belt enters an electrolytic stripping tank, the silver layer in the non-conductive functional area of the lead frame is stripped through electrolytic reaction, the electrolyte contains 120g/L stripping silver powder, the electrolytic temperature is 30 ℃, and the current density is 6A/dm 2 And the electrolytic silver stripping time is 10 seconds. And then spray rinsing with RO deionized water for three times to remove the electrolytic solution.
And step 10, allowing the material belt to enter an acid activation tank, wherein an acid activation solution contains 120g/L of methanesulfonic acid, the activation temperature is 25 ℃, and the activation time is 10 seconds (the activation aims to increase the bonding force between a tin plating layer and a nickel layer). And then spray-washing and cleaning with RO deionized water for three times to remove the activated acid solution.
Step 11, the material belt enters a tin plating bath, the tin plating solution consists of 100g/L of methanesulfonic acid and 150g/L of tin methanesulfonate, the solution temperature is 26 ℃, and the current density is 5A/dm 2 And a 6-micron tin layer is formed on the nickel layer of the non-conductive functional area, so that good weldability can be provided for the packaged optocoupler pin. After tinning, the material belt needs to be sprayed and washed by RO deionized water for four times, so that the residual plating solution is thoroughly removed. And obtaining the tin-nickel-copper-nickel plating layer.
Step 12, the material belt enters a tin protective tank, tin protective solution consists of 120g/L tin protective agent, the temperature of the solution is 30 ℃, and the current density is 3A/dm 2 And a 0.1-micron tin protective layer is formed on the tin layer, so that good protection performance can be provided for the packaged optical coupler pin. And then, spraying, washing and cleaning the substrate for three times by using RO deionized water to thoroughly remove the residual protective solution.
Step 13, the same as in step 13 of example 1.
And step 14, passing the material belt through a hot air drying box, drying at 180 ℃ for 30 seconds, completely drying the surface of the material belt, receiving materials and packaging, and completing the electroplating process.
The plating layer prepared in the embodiment is subjected to a plating layer binding force firmness test, the plating layer is bent for 5 times at 90 degrees under the test conditions of 25 ℃ and 85% of relative humidity, a straight plug-in unit is twisted for 5 circles at 360 degrees, and the plating layer does not fall off; the plating layer of the surface mount device plane piece by the grid drawing method has 100 percent of no falling, and meets the requirements of post-processing and bending procedures of products.
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 plating layer prepared by the embodiment has excellent high temperature resistance, does not generate bubbles at 350 ℃/5s under the high-temperature baking test condition, and can meet the requirements of welding wires and wave soldering; no bubble at 300 ℃/5 minutes, can meet the requirements of welding wire and wave soldering; no foaming at 175 deg.C/3 hr and 150 deg.C/8 hr, and can meet the curing engineering requirement of packaging process.
The tin-nickel-copper-nickel plating layer prepared by the embodiment has no bubbling and peeling at 200 ℃/10 minutes, and meets the easy tin feeding property and firmness of pin welding.
Example 3
Step 5The material belt enters a copper sulfate bright acid copper plating tank, plating solution consists of 200g/L of copper sulfate, 40mL/L of sulfuric acid, 90mg/L of chloride ions, 5mL/L of acid copper cylinder opening agent and 0.5mL/L of brightening agent, the temperature is 28 ℃, the plating solution is continuously filtered and stirred in an auxiliary circulation mode, and the current density is 4A/dm 2 The thickness of the bright electroplated copper layer is 2.5 μm. Then, the plating solution is sprayed and washed for four times by RO deionized water, and the residual plating solution is thoroughly removed.
Step 7, the material belt enters a pre-silver plating groove, the pre-silver plating solution consists of 80g/L potassium cyanide and 8g/L silver cyanide (containing silver), the temperature of the solution is 28 ℃, and the current density is 6A/dm 2 And forming a silver layer of 0.25 μm on the nickel layer. And then, carrying out spray rinsing for three times by using RO deionized water to remove the plating solution.
Step 8, the material belt enters a local silver plating tank, a special rotating wheel mould is matched, plating solution is continuously sprayed, the silver plating solution consists of 100g/L of potassium cyanide, 18g/L of silver cyanide, additive and brightener which are 5mL/L respectively, the temperature of the solution is 25 ℃, and the current density is 4A/dm 2 And forming a silver layer with the thickness of 3 mu m on the pre-plated silver layer of the conductive functional area. And then the plating solution is removed by spraying and washing the solution for five times by RO deionized water. Thus obtaining the silver-nickel-copper-nickel plating layer.
Step 9, the material belt enters an electrolytic stripping tank, the silver layer in the non-conductive functional area of the lead frame is stripped through electrolytic reaction, the electrolyte contains 80g/L stripping silver powder, the electrolytic temperature is 25 ℃, and the current density is 4A/dm 2 And the electrolytic silver stripping time is 15 seconds. And then spray rinsing with RO deionized water for three times to remove the electrolytic solution.
And step 10, the material belt enters an acid activation tank, acid activation solution contains 120g/L of methanesulfonic acid, the activation temperature is 25 ℃, the activation time is 15 seconds, (the purpose of activation is to increase the bonding force between the tin coating and the nickel coating). And then spray-washing and cleaning with RO deionized water for three times to remove the activated acid solution.
Step 11, the material belt enters a tin plating bath, the tin plating solution consists of 100g/L of methanesulfonic acid and 120g/L of tin methanesulfonate (containing tin), the solution temperature is 26 ℃, and the current density is 4A/dm 2 And a 5.5-micron tin layer is formed on the nickel layer of the non-conductive functional region, so that good weldability is provided for the packaged optical coupling pin. After tinning, the material belt needs to be sprayed and washed by RO deionized water for four times, so that the residual plating solution is thoroughly removed. And obtaining the tin-nickel-copper-nickel plating layer.
Step 12, the material belt enters a tin protective tank, tin protective solution consists of 100g/L tin protective agent, the temperature of the solution is 25 ℃, and the current density is 4A/dm 2 And a 0.08-micrometer tin protective layer is formed on the tin layer, so that good protection performance can be provided for the packaged optical coupler pin. And then, spraying, washing and cleaning the substrate for three times by using RO deionized water to thoroughly remove the residual protective solution.
Step 13, the same as in step 13 of example 1.
And step 14, passing the material belt through a hot air drying box, drying at 160 ℃ for 30 seconds, completely drying the surface of the material belt, receiving materials, packaging and finishing the electroplating process.
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 layer prepared in the embodiment is subjected to a plating layer binding force firmness test, the plating layer is bent for 5 times at 90 degrees under the test conditions of 25 ℃ and 85-95% of relative humidity, a straight plug-in unit is twisted for 5 circles at 360 degrees, and the plating layer does not fall off; the plating layer of the surface mount device plane piece lattice drawing method has no 100% falling off, and the requirement of the post-processing bending procedure of the product is met.
The silver-nickel-copper-nickel plating layer prepared by the embodiment has excellent high temperature resistance, does not generate bubbles at 350 ℃/5s under the high-temperature baking test condition, and can meet the requirements of welding wires and wave soldering; no bubble at 300 ℃/5 minutes, can meet the requirements of welding wire and wave soldering; no foaming at 175 deg.C/3 hr and 150 deg.C/8 hr, and can meet the curing engineering requirement of the package process.
The tin-nickel-copper-nickel plating layer prepared by the embodiment has no bubbling and peeling at 200 ℃/10 minutes, and meets the easy tin feeding property and firmness of pin welding.
Comparative example 1
Only differs from example 1 in that step 6 is omitted.
The silver-copper-nickel plating and the tin-copper-nickel plating prepared in this comparative example were inferior in flatness and plumpness to those of example 1.
Performing a plating layer bonding force firmness test on the plating layer prepared by the comparative example, bending the plating layer for 5 times at 90 degrees under the test conditions of 25 ℃ and 85-95% of relative humidity, and twisting the straight plug-in unit for 5 turns at 360 degrees to generate cracks on the plating layer locally; 2% of the coating of the surface-mounted piece falls off by a lattice drawing method, and the requirement of a post-process machining and bending process of a customer product is not met.
The silver-copper-nickel plating layer prepared by 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; no foaming at 175 ℃/3 hours; no foaming occurred at 150 ℃ for 8 hours.
The tin-copper-nickel plating layer prepared by the embodiment has slight bubbling phenomenon at 200 ℃/10 minutes, and does not meet the firmness of pin welding.
The electroplating process of the optocoupler lead frame (preparation method of the multifunctional composite electroplated layer of the optocoupler lead frame) is suitable for the optocoupler lead frame and the optocoupler lead frame made of the copper base material, and the electroplating process (the plating layer comprises but is not limited to nickel-copper-nickel-silver/tin combination) can be increased or decreased according to the product characteristics to adjust the thickness of the plating layer. Such modifications do not require inventive faculty to those skilled in the art, and are intended to be within the scope of the invention as defined by the claims.
The above-described embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solutions of the present invention can be made by those skilled in the art without departing from the spirit of the present invention, and the technical solutions of the present invention are within the scope of the present invention defined by the claims.
Claims (10)
1. A multifunctional composite electroplated layer of an optocoupler lead frame is characterized in that a nickel layer, a copper layer, a nickel layer and a functional layer are sequentially arranged in the direction from a base 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.
2. A method for preparing a multifunctional composite electroplated coating of an optocoupler lead frame according to claim 1, characterized by comprising the steps of:
step 1, priming nickel plating is carried out on an optocoupler lead frame to obtain an optocoupler lead frame electroplated with a primed nickel layer;
step 2, pre-plating alkali copper on the optical coupling lead frame electroplated with the priming nickel layer to obtain an optical coupling lead frame pre-plated with alkali copper;
step 3, carrying out acid copper plating on the optical coupling lead frame pre-plated with the alkali copper to obtain an optical coupling lead frame plated with a copper layer;
step 4, carrying out nickel plating on the optical coupling lead frame of the electroplated copper layer to obtain the optical coupling lead frame of the electroplated nickel layer; according to concentration, the plating solution for nickel plating comprises 60-90g/L of nickel sulfamate, 8-15g/L of nickel chloride, 40-50g/L of boric acid, 0.5-2mL/L of main brightening agent for nickel plating and 60-120mL/L of softening agent for nickel plating;
step 5, pre-silvering the optical coupling lead frame with the electroplated nickel layer to obtain a pre-silvered optical coupling lead frame;
step 6, carrying out silver plating on the pre-silvered optical coupler lead frame in a conductive function area to obtain an electroplated silver optical coupler lead frame;
step 7, performing silver stripping treatment on the non-conductive functional area of the electro-silvered optical coupling lead frame to obtain the silver-stripped optical coupling lead frame;
and 8, carrying out tin plating on the silver-removed optocoupler lead frame in a non-conductive functional area to obtain the optocoupler lead frame with a multifunctional composite electroplated layer.
3. The preparation method of claim 2, wherein in step 1, the plating solution for priming nickel plating comprises 150-180g/L nickel sulfate, 45-50g/L nickel chloride, 45-50g/L boric acid, 0.5-2mL/L main brightening agent for nickel plating, and 60-120mL/L softening agent for nickel plating; 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 μm.
4. The preparation method according to claim 2, wherein in the step 2, the plating solution for pre-plating the alkali copper comprises 15-30g/L cuprous cyanide and 80-120g/L sodium cyanide by concentration; the temperature of a plating solution for pre-plating the alkali copper is 35-45 ℃; the current density of the pre-plated alkali copper is 4-10A/dm 2 The thickness of the plating layer of the pre-plated alkali copper is 1-3 mu m.
5. The preparation method according to claim 2, wherein in step 3, the acidic copper plating bath comprises 180-220g/L copper sulfate, 30-40mL/L sulfuric acid, 80-120mg/L chloride ion, 5-8mL/L acid copper cylinder opening agent and 0.4-0.8mL/L brightener; the temperature of the plating solution of the acid copper plating is 22-28 ℃; the current density of the acid copper plating is 2-6A/dm 2 The thickness of the plating layer of the acid copper plating is 2-5 mu m.
6. The method according to claim 2, wherein in 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 plating layer of the nickel plating is 1-3 μm.
7. The method according to claim 2, wherein in step 5, the plating solution for 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 calculated by silver ions; the current density of the pre-silvering is 2-6A/dm 2 The thickness of the pre-silvered coating is 0.1-0.2 μm.
8. The method according to claim 2, wherein in step 6, the plating solution for silver plating of the conductive functional region comprises potassium cyanide, silver cyanide and an additive; the concentration of the potassium cyanide is 80-120g/L; the concentration of the silver cyanide is 10-20g/L calculated by silver ions; the concentration of the additive is 5-10mL/L; the current density of silver plating of the conductive functional area is 100-150A/dm 2 The conductive functional region being plated with silverThe thickness of the plating layer is 1.5-4 μm.
9. The method according to claim 2, wherein in step 8, the plating solution for plating the non-conductive functional regions with tin includes methanesulfonic acid and tin methanesulfonic acid; the concentration of the methanesulfonic acid is 80-100g/L; the concentration of the tin methane sulfonate is 100-150g/L according to the content of tin; the current density of the tin plating of the non-conductive functional area is 2-6A/dm 2 The thickness of the plating layer of the tin plating of the non-conductive functional area is 3-5 μm.
10. The preparation method according to claim 2, wherein in step 1, the method further comprises the steps of degreasing and activating before priming nickel plating of the optical coupling lead frame; the optical coupler lead frame is an iron-based optical coupler lead frame or a copper-based optical coupler lead frame;
in step 8, the step of acid activation is also included before the non-conductive functional region is tinned, and the step of electroplating a tin protective layer is also included after the non-conductive functional region is tinned;
in the steps 1-8, the method also comprises the step of washing for 3-5 times after each electroplating is finished.
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