How to form a smooth and even metal plating layer on the surface of ABS plastic parts?

Firstly, fix the plastic part on the conductive tool, that is, the hanger, so that it can be connected to the power source to form a closed loop, so that the electroplating can proceed smoothly. This process factory is called racking.

The hanging method and the conductive nozzle are particularly critical for obtaining the required conductive effect.

Secondly, it is to remove oil, wax, and clean the grease, dust, sweat and other substances on the surface of the parts. If it is not cleaned up, it will directly affect the processing effect of the subsequent process and the appearance of electroplating on the surface of the part.

The third step is coarsening

The purpose of coarsening:

1. Make the plastic surface hydrophilic and create anchor points. The micro-holes formed are used for subsequent electroplating to form welding points to obtain maximum adhesion. The solder joints are chemically active and provide a mechanism for absorbing the palladium activator.

2. Passivate the adhesive layer of the hanger to avoid plating on the hanger.

The principle of coarsening:

The strong acidity of the roughening solution is used to dissolve the B (butadiene) component in the ABS plastic, forming a microscopic rough "dovetail" small hole on the surface of the part, which increases the contact area between the plating surface and the part. And some polar hydrophilic groups such as -OH, -SO3H, ﹥C=0 are produced on the surface of the part, which makes the surface of the part hydrophilic.

The fourth step is sensitization

Purpose of sensitization:

It provides a catalytic effect for the subsequent electroless plating, and promotes the reduction reaction of the subsequent electroless plating on the surface of the material to precipitate metal.

Principle of sensitization:

Using the reduction effect of stannous chloride on palladium chloride, a colloidal complex is formed with tetravalent tin ion and metal palladium. The metal palladium is adsorbed to the non-metal surface, and then the metal palladium is exposed during the cleaning process, and the metal core of the palladium becomes a catalyst for electroless nickel plating.

The fifth step, debonding

The purpose of debonding:

The colloidal palladium adsorbed on the surface of the plastic in the catalytic liquid does not have catalytic activity because it is surrounded by divalent tin ions (Sn2+), and the divalent tin around the palladium needs to be dissolved through the degumming process to make it exposed and truly catalytic active.

The principle of debonding:

The debonding agent removes the stannous ions on the plastic surface to expose the metal palladium. The metal palladium acts as a catalyst in the chemical nickel and promotes the production of chemical nickel.

The sixth step, chemical nickel

Purpose of chemical nickel:

All the processes before this process are prepared for the smooth progress of this process. After the chemical reaction, the surface of the part is covered with a conductive nickel/phosphorus alloy layer (about 0.2um), making the original non-conductive Plastic parts become conductors, making it a reality for a series of electroplating (copper, nickel, chromium) processes.

The principle of chemical nickel:

According to the "atomic hydrogen state theory" to explain, in the presence of a catalyst, the following series of redox reactions occur:

H2PO2 ﹣+ H2O→H++ HPO3 2 ﹣ +2H

△Ni2﹢+ 2H →Ni + 2H﹢

H2PO2 ﹣+ H →P + H2O + OH﹣

△ H2PO2 ﹣+ H2O →H + HPO3 2 ﹣+ H2↑

During the reaction, Ni-P alloy and hydrogen are mainly generated.

The seventh step, coke copper/pre-plated copper

The eighth step, acid copper/light copper

The ninth step, semi-gloss nickel

The tenth step, light nickel

The eleventh step, Bright chrome