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Figure out the difference between vacuum plating and water plating

Nov 14, 2018

Figure out the difference between vacuum plating and water plating

 

If someone asks you, what is electroplating? What would you say? Some say water plating, some say vacuum plating. Which is right? In fact, "electroplating" means different things in different industries. For example, in the current mobile phone industry, there are few applications of water electroplating. In many people's minds, electroplating generally refers to vacuum plating, while in the sanitary ware industry, water electroplating is widely applied, of course, common electroplating refers to water electroplating. Both water electroplating and vacuum plating belong to electroplating film. Let's start from the classification of coating film, and see the difference between different types of coating.

 

Electroplating products are classified as follows according to the forming method:

 

 1. Solid phase method: --- > chemical change;

2. Liquid phase method: --- > chemical change

3. Meteorological method: -- > chemical and physical changes

 

The classified as follows:

 

 

The common coating methods include: water plating, anodization, vacuum evaporation, vacuum spatter and ion plating.

 

Water plating:

Keywords: anodic dissolution, cathode attachment, electrochemical reaction

The water electroplating method is mainly used to create high reflector effect and increase adhesion layer, etc. Its advantages are large area of plating, low cost, high toxicity of electrolyte and large industrial pollution.

 

Water-plating line


Anodic oxidation process:

Keywords: metal oxide film, electrochemical reaction

Anodic oxidation can also be made into Ta2O2, TiO2, ZrO2, Nb2O5, HfO2, WO3, etc., mainly used as protective film or coloring decorative film.

 

Anodized product

Vacuum evaporation is also called thermal evaporation

Process key words: high temperature dissolved evaporation, deposition after covering film

According to the different heating methods of film materials, vacuum evaporation can be divided into indirect heating type and direct heating type.

 1. Indirect heating type: only for the evaporation source, indirectly causing the film material on it to evaporate due to heat; 

2. Direct heating type: use high-energy particles (electron beam, plasma or laser) or high frequency to directly heat up the film material on the evaporation source and evaporate; *


 To avoid evaporation of the source (container) along with the film material, the melting point of the source material must be higher than the boiling point of the film material.

 

Evaporation principle


Resistance heating and evaporation

The film material is indirectly heated by the thermal energy generated by the electric current passing through the resistance. The device is as follows:

 

Resistance heating and evaporation

Disadvantages of resistance heating:

1. It is necessary to heat the evaporation source before transferring heat to the film material. The evaporation source is easy to act on the material or lead impurities;

2. The heating temperature of evaporation source is limited, and most of the oxide at high melting point cannot be melted and evaporated;

 3. Limited evaporation speed;

4. If the coating material is a compound, it may be decomposed;

5. The film is not hard, with low density and poor adhesion.

 

Sputtering coating

Keywords: ionized inert gas, target bombardment, target peeling, deposition, cooling, film formation

Principle of sputtering coating machine is cavity pumping air into vacuum state, directly by the membrane material (target) as electrodes, using electrodes see electricity 5 kv ~ 15 kv plasma bombardment of target material, ventilation with gas at the same time, gas ionization, moving particles within the plasma, ion impact target material and the material atoms from which deposited on the substrate surface, cooling the condensed into a film.

 

Magnetron Sputtering Deposition

The electrode structure is improved on the basis of dc or radio frequency sputtering, that is, a permanent magnet is arranged on the inner side of the cathode, and the magnetic field is perpendicular to the direction of the electric field in the dark area, so as to restrain the operation of charged particles with magnetic field. This sputtering method is called magnetron sputtering.

Magnetron sputtering schematic diagram

As the force of the magnetic field is perpendicular to the direction of the electrons, the centripetal force of electron cyclogenesis will be formed. At this time, the probability of collision between neutral species is increased, and thin films can be made at low pressure.

Besides low pressure, the other two advantages of magnetron sputtering are high speed and low temperature.

But magnetron sputtering also has some problems, such as for planar magnetic control electrode magnetic control electrode, the central and peripheral target material is not perpendicular to the magnetic field component of the power plant more and more small, i.e. parallel to target surface of magnetic field component is small, in a circular area on the surface of the target material by sputtering unusually fast, while the central and edge sputtering less, so it will be a w-shaped erosional valley, reduce the utilization rate of target material, and may affect the film uniformity.

 

Ion plating principle

Ion Plating

Keywords: vacuum gas discharge, dissociation target, bombardment base material

The main principle is to dissociate the film material into an ion state by using the gas discharge phenomenon and then deposit it on the substrate.

The basic electroplating system for ion plating is the PVD system, which only adds reactive gases to make it react with the film material after evaporation and then deposits on the substrate to form compounds. Therefore, the composition of the film coating is different from the original film material, and it is a compound of the base material.

Ion plating basically consists of three steps:

1. Transforming solid atoms into gaseous atoms: various evaporation sources and various sputtering mechanisms can be vacuum evaporation to achieve this purpose;

2. Turn gaseous atoms into ionic states to increase the degree of ionization of the raw material (usually up to 1). Various of ion elements can be used to transfer energy to the raw material atoms to achieve the degree of ionization at the beginning;

3. Increase the energy of the ionic material to improve the quality of the film: the capacity of accelerating the ions can be achieved by basically adding appropriate negative bias.

 

The characteristics of ion plating are as follows :

1. Ion plating can be carried out at a lower temperature of 600 degrees;

 2.  Good adhesion;

3. Good diffracted - charged atomic energy reaches all the basic surface and deposits the coating;

 4. The deposition speed is fast, reaching 1~5um, while the sputtering speed of the secondary plate is only 0.01~1.0um/min;

5. The processing property and the selectivity of thin film materials are wide. Besides metals, ceramics, glass and plastics can be processed.

 

PVD three categories of technical characteristics comparison

 

Above is the simple combing of common coating process. If you want to share more interesting contents, you can leave a message at the end of the article.

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