What is Electroplating Intermediate?

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1 February 2023
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Electroplating intermediates refer to a class of fine chemicals used as electroplating additives. Unlike the salt used in the plating production process, the electroplating intermediate is an additive material for electroplating modification in terms of grain size, gloss, thickness, and plating speed.

How Can Electroplating Intermediates be Classified?
According to the different plating types, electroplating intermediates can be divided into nickel plating intermediates, copper plating intermediates, tin plating intermediates, gold plating intermediates, silver plating intermediates, etc. Meanwhile, according to different functions, electroplating intermediates can be further divided into surfactants, brighteners, wetting agents, softeners, anti-fog agents, and alike.

Introduction to Zinc Electroplating Intermediates
Zinc electroplating intermediates include potassium chloride acidic zincs, cyanide-free and cyanide basic zincs, as well as trivalent chromium passivation products of zincs.

Potassium Chloride Acidic Zinc Intermediates include: Bianzacetone (BAR), Bianzadiacetone (BZA), O-chlorobenzaldehyde (OCBA), high temperature carrier (OCT-5/15).

Cyanide-free and Cyanide-free Basic Zinc Intermediates include: benzyl nicotinic acid inner salt (BPC), imidazole propoxy condensate (IMZE), hexamethylene triquaternary ammonium chloride (HETM), and DPE-III.

Trivalent Chromium Passivation Intermediates of Zinc include: basic chromium sulfate, chromium nitrate, complexing agent, and accelerator.

Bianzadiacetone (BZA) is a potassium chloride acid zinc plating brightener, which is an alternative to benzylidene acetone and o-chlorobenzaldehyde. It consists of the passivation effect and white and bright coating. OCT-5/15, made by sulfonation of alkylphenol polyoxyethylene ether, is a carrier for potassium chloride galvanizing. Because its structure contains a benzene ring group and according to the principle of compatibility of those with similar chemical structures, the emulsification effect of OCT-5/15 with BAR, BZA, and OCBA that also contain a benzene ring structure should be better than that of fatty alcohol polyols that do not contain a benzene ring structure.

Cyanide-free alkaline galvanizing is an environmentally friendly electroplating process due to the lack of highly toxic cyanide within the electroplating bath, and the related electroplating wastewater can be treated easily. Some galvanizing intermediates are: Bianyl nicotinic acid inner salt (BPC), Imidazole propoxy condensate (IMZE), and DPE-III, which can be used to prepare cyanide-free alkaline zinc plating additives. Among them, BPC, IMZE, and hexamethylene triquaternary ammonium chloride (HETM) are used as cyanide alkaline zinc plating additives, while HETM, also referred to as ETP, can also be used in electroless copper plating additives.

The trivalent chromium blue-white passivation intermediates of zinc include: basic chromium sulfate, complexing agent, and accelerator B. The trivalent chromium color passivation intermediates of zinc include: chromium nitrate, complexing agent, and accelerator C. The passivation solution is prepared by the addition of the nickel salt, cobalt salt, and the abovementioned intermediates in a specific proportion.

Introduction to Copper Electroplating Intermediates
Copper electroplating intermediates include the alkali copper CB series and acid copper series. Meanwhile, the CB series of alkali copper consists of four intermediates: CB-1, CB-4, CB-5 and CB-6. The acid copper series intermediates include: sodium polydithiodipropane sulfonate (SPS), sodium 3-mercaptopropane sulfonate (MPS), sodium N,N-dimethyldithiocarbonylpropane sulfonate (DPS), isothioureapropanesulfonic acid inner salt (UPS), 3-(benzothiazole-2-mercapto)-propanesulfonate sodium (ZPS), tetrahydrothiazole-2-thione (H1), polyethyleneimine quaternary ammonium salt (PNP), 2-mercaptobenzimidazole (M), ethylenethiourea (N), and polyethylene glycol (P-6000).

Furthermore, SPS is mainly used as an additive in electroplating acid copper plating. As an acidic copper plating intermediate, it is the major additive that can refine the crystallization of plating layers and effectively increase the current density.

SPS is also the major brightener agent in the traditional M and N system acid copper plating.

MPS is an acid copper intermediate, which can enhance the anti-corrosion ability of the copper surface, and it can be used in conjunction with polyether to obtain a bright and ductile coating.

DPS is an acid copper brightener, which can be used in combination with surfactants, such as polyether and wetting agents, or used in combination with sulfur-containing brighteners to obtain bright and ductile coatings. At the same time, it can also be used for the electroless plating of precious metals or as an electroplating stabilizer.

UPS is an acid copper brightener that can be used in combination with polyethylene glycol and anionic surfactants or with other acidic plating solutions such as silver plating and palladium plating.

ZPS is a brightener for copper plating that can be used in combination with polyether and wetting agents or with other sulfur-containing brighteners.

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