White copper and tin plating layer structure with polythiocyanate plated copper as bottom plating layer

Abstract

The utility model discloses a cupronickel-tin plating layer structure taking polythiocyanate plated copper as a bottom plating layer, which comprises a zinc alloy substrate, and a polythiocyanate plated copper layer, a pyrophosphate plated copper layer, an acid copper plating layer, a cupronickel-tin plating layer and a rare earth electrolytic protective film which are sequentially prepared on the zinc alloy substrate from inside to outside. According to GB / T 5270-2005 Metal Covering Layer Electro-Deposition and Chemical Deposition Layer Adhesion Strength Test Method on Metal Matrix, the binding force of a plating layer is tested by a thermal shock method, the binding force meets the standard requirement, an acetate fog test is carried out for 60 hours according to GB / T 10125-2021 Artificial Atmosphere Corrosion Test Salt Spray Test, no corrosives are generated on the surface of a plating piece, and the plating piece has good corrosion resistance. And the prepared plating layer has good corrosion resistance.

Description

TECHNICAL FIELD

[0001] The utility model belongs to metal surface treatment technical field, concretely relates to a kind of white copper tin plating layer structure with polythionic acid salt copper plating as bottom plating layer. BACKGROUND

[0002] Zinc alloy die casting preparation process is simple, low in production cost, and is applied in hardware products and other industries in large quantities. Traditional method adopts copper + nickel + chromium process to prepare protective decorative coating on the surface of zinc alloy die casting, but white people have skin allergic reaction to metal nickel.

[0003] Electroplated high-tin copper-tin alloy is known as electroplated white copper tin in the industry, and does not cause skin allergic reaction, in line with RoHS requirements. Research results show that white copper tin can completely achieve the effect of electroplated nickel in performance, and has similar luster to bright nickel plating layer, good corrosion resistance and wear resistance.

[0004] According to traditional process, zinc alloy die casting adopts cyanide copper plating process to prepare pre-plated copper layer, and then performs pyrophosphate copper plating, acid copper plating and the like. Since cyanide has high pollution problem, the industry is actively developing new cyanide-free copper plating process to replace cyanide copper plating. Polythionic acid salt copper plating is the latest developed cyanide-free copper plating process in the industry, which has performance close to cyanide copper plating, and is currently in the development trial stage.

[0005] According to traditional electroplating process, white copper tin plating layer needs to be protected by chromate electrolytic protection method to improve its discoloration resistance and corrosion resistance, but the use of hexavalent chromium has high pollution problem.

[0006] Reference: [1], Guo Chongwu, electroplated white copper tin process with acid zinc-nickel alloy plating as bottom layer [J], electroplating and finishing, 2018, 37 (12): 536-537. [2], Qin Zuozu, Li Jian San, Xu Jinlai, research progress of cyanide-free copper plating process at home and abroad [J], electroplating and finishing, 2015, 34 (3): 149-152. UTILITY MODEL CONTENTS

[0007] In order to solve the high pollution problem of traditional cyanide pre-plated copper and chromate electrolytic protection, the utility model provides a white copper tin plating layer structure with polythionic acid salt copper plating as bottom plating layer. In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0008] A white copper tin plating layer structure with polythionic acid salt copper plating as bottom plating layer, comprising zinc alloy base body, and polythionic acid salt copper plating layer, pyrophosphate copper plating layer, acid copper plating layer, white copper tin plating layer and rare earth electrolytic protection film prepared in sequence from inside to outside on the zinc alloy base body;

[0009] The thickness of the white copper tin plating layer is 3-7 μm.

[0010] Preferably, the thickness of the polythiocyante copper plating layer is 3-6 μm.

[0011] Preferably, the thickness of the pyrophosphate copper plating layer is 4-9 μm.

[0012] Preferably, the thickness of the acid copper plating layer is 10-22 μm.

[0013] The polythiocyante copper plating process is used to prepare a pre-copper plating layer on the surface of the zinc alloy pressure casting, and the plating layer can form a good bonding force with the substrate. The white copper tin is plated on the copper plating layer, and the electrode potential of the white copper tin plating layer is obviously negative to the electrode potential of the copper plating layer, so that the copper plating layer has an electrochemical protection effect. The plating layer structure can better block the corrosion medium from corroding the substrate.

[0014] Compared with the prior art, the plating white copper tin plating layer structure has the following beneficial effects:

[0015] 1. The plating white copper tin plating layer structure disclosed by the utility model takes polythiocyante copper plating as a bottom plating layer, and uses the polythiocyante copper plating process to prepare a pre-copper plating layer on the surface of the zinc alloy, so that the problem of high pollution caused by the cyanide pre-copper plating process is overcome.

[0016] 2. The plating white copper tin plating layer structure disclosed by the utility model takes polythiocyante copper plating as a bottom plating layer, and uses the rare earth electrolytic protection method to post-process the white copper tin plating layer, so that the problem of high pollution caused by the chromate electrolytic protection is overcome. DRAWINGS

[0017] The drawings described herein are used to provide a further understanding of the utility model, constitute a part of this application, and do not constitute an improper limitation on the utility model, and in the drawings:

[0018] Figure 1 It is the plating layer structure schematic view of the utility model embodiment 1 and embodiment 2. CONCRETE IMPLEMENTING METHOD

[0019] The utility model will be described in detail below by combining with the drawings and specific embodiments, and the illustrative embodiments and the description of the utility model are used to explain the utility model, but do not serve as a limitation on the utility model.

[0020] A plating white copper tin plating layer structure taking polythiocyante copper plating as a bottom plating layer comprises a zinc alloy substrate and a polythiocyante copper plating layer, a pyrophosphate copper plating layer, an acid copper plating layer, a white copper tin plating layer and a rare earth electrolytic protection film prepared on the zinc alloy substrate from inside to outside in sequence.

[0021] According to the current pretreatment process, the zinc alloy pressure casting substrate is subjected to wax removal, oil removal and activation.

[0022] The zinc alloy pressure casting is pretreated, and then a polythionic acid salt copper plating layer is prepared by using a polythionic acid salt copper plating process.

[0023] Preferably, the thickness of the polythionic acid salt copper plating layer is 3-6 μm.

[0024] Preferably, the polythionic acid salt copper plating layer is prepared by using the HT-810 polythionic acid salt copper plating process of Weizhi Huatong:

[0025] Polythionic acid cuprous 17-23 g / L, polythionic acid sodium 100-160 g / L, potassium sodium tartrate 8-12 g / L, HT-810 brightener 1-2 mL / L, HT-810 running agent 2-4 mL / L, plating bath temperature 45-55 ℃, plating solution pH value 12-13, cathode current density 0.5-1.0 A / dm 2 , cathode moving speed 4-6 m / min, anode current density ≤0.5 A / dm 2 , and using oxygen-free electrolytic copper horn (or copper particle) as anode.

[0026] The zinc alloy pressure casting is pretreated, and then a polythionic acid salt copper plating layer is prepared by using a polythionic acid salt copper plating process.

[0027] Preferably, the thickness of the polythionic acid salt copper plating layer is 3-6 μm.

[0028] The zinc alloy pressure casting is pretreated, and then a polythionic acid salt copper plating layer is prepared by using a polythionic acid salt copper plating process.

[0029] Preferably, the thickness of the polythionic acid salt copper plating layer is 3-6 μm.

[0030] The zinc alloy pressure casting is pretreated, and then a polythionic acid salt copper plating layer is prepared by using a polythionic acid salt copper plating process.

[0031] Preferably, the thickness of the polythionic acid salt copper plating layer is 3-6 μm.

[0032] Preferably, the polythionic acid salt copper plating layer is prepared by using the HT-810 polythionic acid salt copper plating process of Weizhi Huatong:

[0033] Potassium cyanide 60~95g / L, cuprous cyanide 12~20g / L, potassium hydroxide 5~20g / L, ASEL Y CTA-604 white copper tin tin salt 50~65g / L, ASEL Y CTA-602 zinc supplement 12~25mL / L, ASEL Y CTA-535 Initial white copper tin cylinder opening agent 20~50mL / L, ASEL Y CTA-535 Bri white copper tin brightener 2~6mL / L, ASEL Y CTA-535 WA white copper tin wetting agent 0.5~5mL / L, plating solution pH 12.5~13.5, plating bath temperature 45~55℃, cathode current density 1.5~2.5A / dm 2 , cathode moving 4~6m / min.

[0034] The white copper tin plated zinc alloy die casting is prepared into a rare earth electrolytic protection film by using a rare earth electrolytic protection process.

[0035] Preferably, the rare earth electrolytic protection film is prepared by using a rare earth electrolytic protection process developed by Super Bond Chemical.

[0036] Cerium acetate 1~5g / L, HEDP complexing agent 5~30g / L, sodium molybdate 5~10g / L, anhydrous sodium carbonate 100~150g / L, bath pH 11.5~12.5, cathode current density 0.5~1.5A / dm 2 , room temperature operation, using the plated part as the cathode and a titanium plate as the anode, electrolysis for 60~120s.

[0037] The white copper tin plated zinc alloy die casting is prepared into a rare earth electrolytic protection film by using a rare earth electrolytic protection process. Example 1

[0038] As shown in Figure 1 , a white copper tin plated layer structure with a polythiocyanate copper plating as a bottom plating layer comprises a zinc alloy substrate 1, and a polythiocyanate copper plating layer 2, a pyrophosphate copper plating layer 3, an acid copper plating layer 4, a white copper tin plating layer 5, and a rare earth electrolytic protection film 6 prepared in sequence from inside to outside on the zinc alloy substrate 1.

[0039] 1. Pretreatment:

[0040] The zinc alloy die casting substrate 1 is subjected to "chemical dewaxing → water washing → ultrasonic dewaxing → water washing → ultrasonic degreasing → water washing → activation → water washing".

[0041] 2. Polythiocyanate copper plating:

[0042] The polythiocyanate copper plating layer 2 is prepared by using HT-810 polythiocyanate copper plating process of Zunyi Huatong after the pretreatment of the zinc alloy die casting, and the plating layer thickness is 4μm.

[0043] Polymeric cuprous thiocyanate 18 g / L, polymeric sodium thiocyanate 120 g / L, potassium sodium tartrate 10 g / L, HT-810 brightener 1.5 mL / L, HT-810 running agent 3 mL / L, bath temperature 53 °C, bath pH 12.3, cathode current density 0.7 A / dm 2 , cathode moving speed 5 m / min, anode current density 0.4 A / dm 2 , using oxygen-free electrolytic copper horn as anode.

[0044] 3. Pyrophosphate copper plating:

[0045] After polymeric thiocyanate copper plating of zinc alloy die castings, a pyrophosphate copper layer 3 is prepared by using the current pyrophosphate copper plating process, and the plating layer thickness is 7 μm.

[0046] 4. Acid copper plating:

[0047] After pyrophosphate copper plating of zinc alloy die castings, an acid copper plating layer 4 is prepared by using the current acid copper plating process, and the plating layer thickness is 15 μm.

[0048] 5. White copper tin plating:

[0049] After acid copper plating of zinc alloy die castings, a white copper tin plating layer 5 is prepared by using ASELY CTA-535 white copper tin plating process of Superbond Chemicals, and the plating layer thickness is 5 μm.

[0050] Potassium cyanide 75 g / L, cuprous cyanide 15 g / L, potassium hydroxide 12 g / L, ASELY CTA-604 white copper tin tin salt 55 g / L, ASELY CTA-602 zinc supplement 16 mL / L, ASELY CTA-535 Initial white copper tin tank opening agent 35 mL / L, ASELY CTA-535 Bri white copper tin brightener 4 mL / L, ASELY CTA-535 WA white copper tin wetting agent 3 mL / L, bath pH 12, bath temperature 50 °C, cathode current density 1.9 A / dm 2 , cathode moving speed 5 m / min.

[0051] 6. Rare earth electrolytic protection:

[0052] After white copper tin plating of zinc alloy die castings, a rare earth electrolytic protection film 6 is prepared by using the rare earth electrolytic protection process developed by Superbond Chemicals.

[0053] Cerium acetate 4 g / L, HEDP complexing agent 25 g / L, sodium molybdate 10 g / L, anhydrous sodium carbonate 130 g / L, bath pH 12 (pH is adjusted by sodium hydroxide solution), cathode current density 1 A / dm 2 , room temperature operation, using plated part as cathode and titanium plate as anode, electrolysis for 90 s.

[0054] 7. Drying:

[0055] After rare earth electrolytic protection, zinc alloy die castings are subjected to "water washing → pure water washing → drying". Example 2

[0056] like Figure 1 As shown, a white copper tin plating structure with polythiocyanate copper plating as the base plating layer includes a zinc alloy substrate 1, and a polythiocyanate copper plating layer 2, a pyrophosphate copper plating layer 3, an acid copper plating layer 4, a white copper tin plating layer 5, and a rare earth electrolytic protective film 6 prepared on the zinc alloy substrate 1 from the inside to the outside.

[0057] 1. Pre-treatment:

[0058] The zinc alloy die-casting substrate 1 undergoes "chemical dewaxing → water washing → ultrasonic dewaxing → water washing → ultrasonic degreasing → water washing → activation → water washing".

[0059] 2. Polythiocyanate copper plating:

[0060] After pretreatment of the zinc alloy die casting, the polythiocyanate copper plating layer 2 was prepared using the HT-810 polythiocyanate copper plating process of Zunyi Huitong, and the coating thickness was 4 μm.

[0061] Polythiocyanate cuprous acid 22g / L, polythiocyanate sodium 150g / L, potassium sodium tartrate 10g / L, HT-810 brightener 1.5mL / L, HT-810 moving agent 3mL / L, plating tank temperature 52℃, plating solution pH 12.2, cathode current density 0.8A / dm 2 , cathode movement 5m / min, anode current density 0.3A / dm 2 , using oxygen-free electrolytic copper particles as anode.

[0062] 3. Pyrophosphate copper plating:

[0063] After the zinc alloy die casting is subjected to polythiocyanate copper plating, a pyrophosphate copper plating layer 3 is prepared using the existing pyrophosphate copper plating process, and the coating thickness is 7 μm.

[0064] 4. Acid copper plating:

[0065] After the zinc alloy die casting is subjected to pyrophosphate copper plating, an acid copper plating layer 4 is prepared using the current acid copper plating process, and the coating thickness is 15 μm.

[0066] 5. White copper tin plating:

[0067] After the zinc alloy die casting is plated with acid copper, a white copper tin coating 5 is prepared using the ASELY CTA-535 white copper tin coating process of Chaobang Chemical, with a coating thickness of 5 μm.

[0068] Potassium cyanide 80 g / L, cuprous cyanide 17 g / L, potassium hydroxide 12 g / L, ASEL Y CTA-604 white copper tin tin salt 60 g / L, ASEL Y CTA-602 zinc supplement 19 mL / L, ASEL Y CTA-535 Initial white copper tin cylinder opening agent 35 mL / L, ASEL Y CTA-535 Bri white copper tin brightener 4 mL / L, ASEL Y CTA-535 WA white copper tin wetting agent 3 mL / L, plating solution pH is 12, plating bath temperature is 50℃, cathode current density is 2.2 A / dm 2 , cathode moves at 5 m / min.

[0069] 6、Rare earth electrolytic protection:

[0070] After the white copper tin plating of the zinc alloy die casting, a rare earth electrolytic protection film 6 is prepared by using the rare earth electrolytic protection process developed by Super Chemical Industry.

[0071] Cerium acetate 3 g / L, HEDP complexing agent 20 g / L, sodium molybdate 8 g / L, anhydrous sodium carbonate 120 g / L, bath pH is 12 (pH is adjusted by sodium hydroxide solution), cathode current density is 0.8 A / dm 2 , room temperature operation, using plated parts as cathode and titanium plate as anode, electrolysis for 100 s.

[0072] 7、Drying:

[0073] After the rare earth electrolytic protection of the zinc alloy die casting, water washing, pure water washing and drying are carried out.

[0074] Test Example 1:

[0075] The white copper tin plated sample of the zinc alloy die casting prepared in Example 1 and Example 2 is subjected to acetate salt spray test for 60 h according to GB / T 10125-2021 “Artificial Atmosphere Corrosion Test Salt Spray Test”, and the surface of the plated part is free of rust, which is higher than the requirement of GB / T 9797-2005 “Metallic Coating Nickel+Chromium and Copper+Nickel+Chromium Electroplated Layer” standard.

[0076] Test Example 2:

[0077] The white copper tin plated sample of the zinc alloy die casting prepared in Example 1 and Example 2 is subjected to constant humidity test under the condition of temperature 40℃ and relative humidity 93% for 1000 h according to GB / T 2423.3-2016 “Electrical and Electronic Products Basic Environmental Test Procedure Test Ca: Constant Humidity Test Method”, and the plated layer has no visible change. The test shows that the discoloration resistance of the plated layer prepared by the utility model fully meets the customer's requirements.

[0078] Test Example 3:

[0079] The zinc alloy pressure casting prepared in the embodiment 1 and the embodiment 2 is plated with white copper tin sample, and the coating adhesion is tested by a thermal shock method according to GB / T 5270-2005 "Metallic Coatings on Metal Substrates - Test Methods for Adhesion - Review" so as to test the coating adhesion. The plated sample is heated to 150 DEG C in a heating furnace and kept for 30 min, and then is taken out and suddenly cooled in water at room temperature. The coating does not appear to bubble and fall off. The test shows that the coating structure prepared by the utility model has good adhesion.

[0080] The above describes the technical solutions provided by the embodiments of the utility model in detail, and the principles and implementation manners of the embodiments of the utility model are described by applying specific examples. The above embodiment description is only applicable to helping understand the principles of the embodiments of the utility model. It should be pointed out that, for those skilled in the art, without departing from the concept of the utility model, a number of modifications and improvements can be made, which all belong to the protection scope of the utility model.

Claims

1. A white tin copper plating layer structure with a polymeric thiocyanate copper strike layer, characterized in that: The zinc alloy base, a polymeric thiocyanate copper plating layer, a pyrophosphate copper plating layer, an acid copper plating layer, a white copper tin plating layer and a rare earth electrolytic protective film are prepared on the zinc alloy base from inside to outside. The thickness of the white copper tin plating layer is 3-7 μm.

2. The white tin copper plating layer structure with a copper plating layer as a base plating layer by using polymeric thiocyanate according to claim 1, characterized in that: The thickness of the polymeric thiocyanate copper plating layer is 3-6 μm.

3. The white tin copper plating layer structure with a copper plating layer as a base plating layer by using polymeric thiocyanate according to claim 1, characterized in that: The thickness of the pyrophosphate copper plating layer is 4-9 μm.

4. The white tin copper plating layer structure with a copper plating layer as a base plating layer by using polymeric thiocyanate according to claim 1, characterized in that: The thickness of the acid copper plating layer is 10-22 μm.

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