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Poor plating (mildew) causes and solutions
- Apr 18, 2017 -

We often find some small white spots on the plated parts, and it is difficult to wipe off, affecting the appearance of the product, and even lead to scrap. This is a relatively common problem of electroplating parts, called electroplating parts.


Through a series of research and analysis, Chunwang found that there are two reasons for the mildew of the electroplated parts. On the one hand, it is caused by irregularities in the electroplating process, that is, the reasons for the production stage. On the other hand, the irregularity of the electroplated parts during transportation and storage, that is, the reason of the logistics storage stage.

(1) Production stage:

In the production process of electroplating parts, it is easy to adhere to mold and microorganisms, so that the electroplated parts form mildew. The electroplating project will generally pass: top hanger → degreasing → water washing → hydrophilic → roughening → water washing → neutralization → water washing → pre-dip → catalysis → water washing → degumming → water washing → electroless nickel plating → water washing → acid activation → flash Copper 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→water washing→drying→downing tools→inspection→packaging→warehouse The cumbersome process. In this process, the raw materials, water, personnel, dust, etc. entering the electroplating workshop may be brought into the mold microorganisms and their spores, and the mold microorganisms as long as there is sufficient moisture (humidity), even if there is no external nutrients, as long as the humidity Conditions such as humidity and pH are suitable, and mold spores can be developed to a certain extent by their own stored nutrients. Therefore, the electroless nickel plating tank, the electroless nickel plating water washing tank, the bright chrome water washing tank, the insufficient drying products, the gloves of the inspection and packaging workers, the packaging and the storage supplies are all important places and stages for the effective adhesion of the mold and rot. Once moldy microorganisms or their spores are present and survived in these places, it will cause mildew on the plated parts.

In the production stage, it is necessary to prevent the occurrence of mildew spots in the electroplated parts by controlling the source of the microbial microorganisms, and sterilizing them at the stage and place where they are effectively adhered, thereby eliminating the survival conditions of the mold microorganisms as much as possible.

The specific solution is as follows:

1. Pay attention to the ventilation, dust removal and sterilization of workshops and warehouses, and minimize or eliminate the source of microbial contamination.

2. Keep the raw materials clean and hygienic. For example, the sodium citrate solution for electroless nickel plating should be heated to about 80 ° C for sterilization after the addition.

3. The water used should be sterilized. The ion exchange resin in the water treatment device should be cleaned regularly with formaldehyde or ethanol; after chemical nickel plating, the appropriate amount of formaldehyde should be added to the washing tank every day, and ethanol should be applied to each cylinder; the water for washing after bright chrome plating must be ultraviolet light. The lamp is sterilized.

4. The temperature and time for plating the plating must be sufficient. It is absolutely forbidden to have water on the workpiece after baking.

5. Inspection of white gauze gloves used by packaging workers must be dry and clean, and plastic film gloves should be worn inside.

6. The electroplated parts should not be placed in the high temperature and high humidity workshop for too long, and the packaging should be quickly moved into the warehouse.

(2) Logistics storage stage:

The electroplating parts are caused by mildew and high temperature in the stage of logistics storage. When the relative humidity is greater than 65%, the metal surface will produce a uniform and thin water film by capillary adsorption, and the periodic change of humidity will form condensation, which will form a micro-battery, which is electrochemical corrosion. That is, the plating layer is oxidized and corroded.

The logistics storage stage prevents the occurrence of mildew on the plated parts mainly by controlling the relative humidity. The specific solution is as follows:

1. The plating parts are best packaged in vacuum packaging bags, which directly insulate the influence of the external environment. The bag should be placed with a small amount of Chunwang desiccant.

2. During the transportation and transportation process, keep the interior of the transportation vehicle clean and dry, and hang the appropriate amount of Chunwang container desiccant according to the space.

3. During the storage process, ensure that the storage environment is dry and ventilated.

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