4 pin 1J0919231 Composite Connector Automobile Waterproof Socket Car Gasoline Pump Wiring Plug for Audi VW

Automotive terminals are mainly made of brass or bronze materials. It is prone to oxidation and discoloration in humid or high temperature environments. The contact resistance increases and affects the terminal conductivity.

In order to solve the oxidation problem of terminals, a tin protective layer with strong oxidation resistance and good conductivity is generally used on automobile terminals.

However, the hardness of the tin plating is low and the friction coefficient is large. As a result, while improving the terminal protection capability, the insertion and extraction force of the electroplated terminal is increased. It is difficult to assemble automotive terminals. Moreover, the tin plating is prone to discoloration when zinc diffuses. Brass The substrate needs to be pre-plated with 0.5μm copper or nickel plating to prevent the diffusion of zinc in the brass substrate from causing discoloration of the tin plating.

In order to solve the problems existing in the existing technology, a chemical plating white bronze (also known as high tin bronze) process for automobile terminals was developed. The coating is silvery white and its hardness is between that of nickel and chromium. It is not easily oxidized and discolored in the atmosphere. It is also very stable in weak acids and weak alkali, and has good soldering and conductive properties. It solves the problems of excessive plug-in and pull-out force and difficult assembly after tin plating of automobile terminals. It also reduces the plating process and coating thickness, while reducing costs. It reduces the insertion and extraction force, improves the protective performance of the terminal and its ability to resist zinc diffusion and coating discoloration.

02. Plating solution composition and process parameters

The functions and effects of each component in the plating solution are as follows:

(1) Copper sulfate and stannous chloride Copper sulfate and stannous chloride are the main salts of the solution.

Their content and proportion have a certain impact on the deposition speed and composition of the coating. Increasing the content of the two will accelerate the deposition speed, but the crystallization of the coating will become coarser and the tendency of the solution to naturally decompose will also increase.

Increasing the content of copper sulfate or stannous chloride alone can increase the content of copper or tin in the coating to a certain extent.

(2) Complexing agents A and B. Complexing agent A is an amine organic substance, and complexing agent B is an organic substance containing carboxyl groups. Complexing agents A and B coordinate with copper ions and stannous ions through carboxyl groups and amine groups.

The redox potential of the two is close to achieve co-deposition of the two metals. At the same time, it prevents the self-oxidation and reduction reaction of copper ions to generate copper and cuprous oxide, improves the stability of the plating solution and improves the quality of the plating layer.

(3) Sulfuric acid ensures that the redox reaction proceeds under acidic conditions to speed up the deposition rate. When the content is low, the deposition rate is slow. If the content is too high, it will cause natural decomposition of the plating solution, reducing the quality of the plating layer and the life of the plating solution.

(4) Sodium hypophosphite The increase in sodium hypophosphite content will speed up the deposition speed of the coating, but too high a content will cause the natural decomposition of the plating solution and make the coating rough. When the sodium hypophosphite content is too low, the coating crystallizes finely, but the deposition rate decreases.

(5) During the reduction process of divalent copper, the stabilizer ZP, in addition to being directly reduced to copper, also has a side reaction to generate cuprous oxide. If co-deposited, the coating will be rough and the bonding force of the coating will be reduced: the stabilizer zP is ferrous iron Inorganic substances can inhibit the occurrence of side reactions, but excessive use will cause the deposition rate to significantly slow down and even stop the reaction.

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