Description And Causes Of Coating Defects in Plastic Plating-Electroplating Process (3)

Description and causes of coating defects in plastic plating-Electroplating process (3).
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21. Mold contamination of the plating bath (mostly seen in the nickel bath, because the environment of PH4-5 is suitable for mold growth), it can be seen that there are many molds embedded in the plating layer. In this situation, disinfection and sterilization measures should be taken. In order to avoid mold pollution, attention must be paid to the implementation of the cylinder opening procedure of the production line.
22. Moss pollutes water quality. The workpiece is rinsed in water containing moss organisms, and the moss adheres to the workpiece, which is firmly attached to the workpiece after drying, which affects the product quality. Attention should be paid to the possibility of moss pollution in spring and a sense of prevention should be established. If the moss contaminates the bath, the moss will be embedded in the coating.
23. The porosity of the coating is high. The high porosity of the coating affects the appearance of the coating, affects the protective characteristics of the coating, shortens the storage period, affects the solderability and the brittleness of the coating. Most of the reasons are dirty plating bath, many metal impurities and many organic impurities.
24. There is a regular difference in coating thickness on the same rack. This is because the projection of cathode and anode pattern is incorrect (the relative position of cathode and anode is not suitable), and the distribution of power lines is uneven.
There is a regular difference in coating thickness on the same rack. This is because the contact resistance of the hook where the workpiece is located is different. Contact with a good coating is thick, vice versa. It's the quality of the hanger.
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If the cathode and anode projection is correct, the aging degree of the two hangers is the same, but the coating thickness is thick on one side and thin on the other side, which changes regularly. This is due to the use of one side of the cathode Yuanbao corrosion or salt cream, resulting in poor electrical contact. .
There are black spots on the surface of some workpieces. There may be two reasons for this:
The main results are as follows: (1) the hanger is aged and cracked, and the acid, alkali and salt seeping from the crack are spurted by compressed gas and splashed on the workpiece, polluting the coating.
(2) the water level of the rinsing water is too low to rinse the workpieces on the upper shelf. Can not rinse the workpiece and hang teeth, drug droplets cross-contamination with each other. Therefore, the rinsing liquid level must be higher than the workpiece at the top of the rack.
(3) cross-contamination of drops.
(4) there is oil in the gas.
(5) pollution caused by manual unloading.
26. The workpiece changes color after drying after plating (yellowing) or discoloration after a short storage time. These are two possible conditions:
The main results are as follows: (1) the concentration of neutralization solution is too thin and the temperature is too low to remove the membrane.
(2) the crystallization of the coating is rough, which increases the difficulty of rinsing and removing the film.
27. There are tin nodules on the surface of the coating. This is because the anode mud pollutes the plating bath, the PP bag is leaked, and when the anode is dissolved, on the one hand, it is transferred to the plating solution in the form of ions, and some are washed into the plating solution in the form of atoms and atomic groups to pollute the plating solution. When the atomic group touches the workpiece, it is embedded in the coating to form a tin nodule.
28. Blackbody heterochromism. That is, the black plastic body becomes gray and black. This is because the frame stays in the lye for too long in the electroplating pretreatment or neutralization tank, and the blackbody has been etched by alkali. The composition of blackbody includes epoxy, leveling agent, curing agent, anti-aging agent, white filler, melanin and so on. When blackbody is corroded by alkali, filler will be exposed. White + black shows gray (heterochromatic) phenomenon.