What should I do if plastic plating parts are prone to mildew? How to prevent it?

In some plastic electroplating plants in the south, there are often small white spots on the plated parts, which are difficult to wipe off. Affect the appearance of the product, and even lead to scrap. Although the conditions of the electroplating process are normal, it is unavoidable, and even appears in large quantities. This is a relatively special electroplating problem, which is called mildew on electroplated parts.

01▶

Process flow

Upper hanger→degreasing→washing→hydrophilic→roughening→washing→neutralization→washing→pre-soaking→catalysis→washing→degumming→washing→electroless platingNickel→water washing→acid activation→flashcopper plating→water washing→acid activation→acid copper plating→water washing→acid activation→water washing→multi-layer nickel plating→water washing→acid activation→ Bright chrome plating→washing→drying→down hanger→inspection→packing→warehousing

02▶

Analysis and discussion

The mold spots on the plastic electroplated parts are formed due to the adhesion of mold microorganisms. The source of mold microorganisms, survival conditions, and the stage and location of effective adhesion to the electroplated parts are the key to discussing the causes and prevention methods of mold spots. .

The high temperature and humidity in the south is an opportunity for the activities of mold and rotting microorganisms. The raw materials, water, personnel, dust, etc. entering the electroplating workshop may bring moldy microorganisms and their spores. As long as the moldy microorganisms have enough moisture (humidity), even other nutrients such as nitrogen compounds, carbon compounds, minerals and vitamins It can grow when there is very little material; even if there is no external nutrients at all, as long as the humidity, temperature, PH value and other conditions are suitable, mold spores can grow to a certain extent with the nutrients stored by themselves.

From the above process, we can see: chemical nickel tank, electroless nickel plating post-washing tank, bright chromium plating post-washing tank, insufficiently dried products, inspection and packaging workers The gloves, packaging and storage supplies are all important places and stages for effective adhesion of mold and rotting microorganisms. Once mold and rotting microorganisms or their spores exist and survive in these places, mold spots will appear on electroplated parts.

03▶

Prevention method

According to the above discussion, the key to preventing mildew on plastic electroplated parts is to control the source of mold and rot microorganisms, minimize the chance of contact with the product; and carry out sterilization treatment at the stage and place where it is effectively attached, and eliminate it as much as possible. Survival conditions of mold microorganisms. The following specific measures can be adopted in actual production:

(1) Pay attention to the ventilation, dust removal and sterilization of workshops and warehouses, and minimize or eliminate the source of mold and rot microorganisms;

(2) Keep the raw materials clean and hygienic. For example, the sodium citrate solution used for electroless nickel plating should be heated to about 80℃ for sterilization treatment before adding;

(3) The water used should be sterilized. The ion exchange resin in the water purification device should be sterilized and cleaned with formaldehyde or ethanol on a regular basis; after electroless nickel plating, an appropriate amount of formaldehyde should be added to the washing tank every day for sterilization, and ethanol should be used when wiping the tank every shift; the water for washing after bright chrome plating must be ultraviolet light Sterilization by lamp irradiation;

(4) The temperature and time for the drying of electroplated parts must be sufficient, and it is absolutely forbidden that there is water on the workpiece after baking;

(5) White gauze gloves used by inspection and packaging workers must be dry and clean, and plastic film gloves should be worn inside;

(6) Packaging supplies should be clean and dry, and desiccant and anti-mold agent can be put in the packaging box;

(7) Electroplated parts should not be placed in a high-temperature and high-humidity workshop for too long, and should be quickly moved into the warehouse after packaging.