Copper deposition is a self catalytic redox reaction, which can be deposited on a non-conductive substrate. The function of copper deposition is to realize the hole metallization, so that the double-sided board and the multi-layer board can realize the interconnection between layers. Copper deposition is applicable to the chemical copper deposition of printed circuit board holes, as well as the chemical copper deposition of iron, steel, stainless steel, zinc alloy and copper alloy surfaces, as well as ceramic copper plating, glass copper plating, resin copper plating, plastic copper plating, diamond copper plating, leaf copper plating, etc.

Copper deposition process equipment: desmear, PTH and PP three in one automatic production line.

Operation safety matters of copper sinking process:

1. During the operation of adding liquid medicine, you must wear rubber gloves resistant to strong acid and strong alkali, gas mask, protective eye mask, protective mask, work shoes resistant to strong acid and strong alkali, work apron and other corresponding safety labor protection articles.

2. The discharge of liquid medicine shall be treated accordingly, and the recovered and reused ones shall be recovered, so as to make full use of renewable resources and meet the national standard discharge standards.

3. There are no, NO2, HCHO and other irritant toxic gases in the air of copper sinking. The workshop staff must wear the corresponding labor protection articles and the air extraction in the workshop should be turned on all day.

4. Always check whether the liquid level of the liquid medicine is normal (in accordance with the liquid level indication in the tank).

5. Always pay attention to the temperature indication on the control panel and whether the filter circulating pump is normal.

6. Before starting the sinking copper wire each time, the first cylinder shall be started by plate. If the plate is to be made for a long time, the dummy plate dragging cylinder shall be made first when the production is resumed.

7. The copper sinking cylinder must be regularly inflated, and all chemical liquid cylinders must be kept clean to avoid dust and other pollution.

8. Pay special attention to backlight test during production, and analyze and adjust the backlight immediately if it is found to be abnormal.

9. Regularly check whether the swing, automatic dosing, regeneration device and fire cow operate well.

Steps of copper deposition process: including the following steps

1. Treatment before copper deposition;

2. Activation treatment;

3. Chemical copper deposition.

Treatment before copper deposition in copper deposition process:

1. Deburring: the base plate goes through the drilling process before copper sinking. Although burr is easy to be generated in this process, it is the most important hidden danger of metallization of inferior holes. It must be solved by deburring process. Mechanical method is usually used to make the hole edge and inner hole wall free of burr or blocking

2. Degreasing:

(1) Source of oil contamination: oil contamination caused by hand contact of the drill bit, handprint during substrate removal and others.

(2) Types of oil pollution: animal and vegetable oils, minerals, etc. The former belongs to saponified oil; The latter belongs to non saponified oils.

(3) Characteristics of oils and fats: animal and vegetable oils belong to saponified oils. The main component is higher fatty acid, which reacts with alkali to produce water-soluble fatty acid salts and glycerol; The chemical structure of mineral oil is mainly a mixture of paraffin, alkene, cycloalkane and chloride, which is insoluble in water and does not react with alkali.

(4) Selection basis of oil removal treatment method: according to the nature of oil and the degree of oil contamination.

(5) Methods: organic solvent and chemical and electrochemical alkaline degreasing were used.

(6) Function and principle: □ saponifiable oil reacts with alkali solution to produce water-soluble fatty acid salt and glycerol. The reaction formula is as follows:

(c17h35coo) 3 + 3 naoh3c17h35coona + C2H5 (OH) 2

□ non saponified oil: mainly depends on surfactants such as OP emulsifier, sodium dodecyl sulfonate, sodium silicate, etc. There are two groups in the structure of these substances, one is hydrophobic; One is hydrophilic. First of all, the emulsifier is adsorbed on the interface between oil and water, and the hydrophobic group has affinity with the oil stain on the surface of the matrix, while the hydrophilic group points to the degreasing liquid. Water is a very strong polar molecule, which reduces the gravitational force between the oil stain and the surface of the matrix. By the convection and agitation of the degreasing liquid, the oil stain leaves the surface of the matrix, achieving the ultimate goal of degreasing.

3. Roughening treatment:

(1) The purpose of roughening is to ensure the good bonding strength between the metal coating and the substrate.

(2) Principle of coarsening: Micro concave pits are generated on the surface of the substrate to increase its surface contact area and form mechanical button bonding with the copper deposit layer to obtain high bonding strength.

(3) Roughening methods and selection: there are basically the following methods, mainly playing the role of acid corrosion and strong oxidation.

Ammonium persulfate sodium persulfate copper chloride solution hydrogen peroxide / sulfuric acid.

Activation treatment of copper deposition process:

1. Purpose of activation: mainly form "initiation center" to make copper deposition uniform.

2. Basic principle of activation: deposit a layer of uniform activation center core particles on the plated non-metallic surface

3. Activation method and selection:

Step activation method: it is proved from production practice that colloidal palladium (one-step activation method) has excellent activation performance, which makes the obtained deposition layer have good binding strength and long service time, but the preparation conditions are strict. The activation solution is light brown.

A. There are three types of colloidal palladium: acidic colloidal palladium, basic colloidal palladium and basic colloidal palladium.

B. Preparation of colloidal palladium: dissolve 1 g of palladium dichloride in 100 ml of hydrochloric acid and 200 ml of aqueous solution. After all the solution is dissolved, put the beaker in a constant temperature water bath at 30 ℃± 1 ℃. Under the condition of stirring, add 2.54 g of tin dichloride (SnCl2 · 2H2O) for reaction for 12 minutes, Then, the two solutions (A and b) are mixed (the composition of solution B is 75 g / L of tin dichloride, 7 g / L of sodium silver oxide nasno447h2o and 200 ml / L of hydrochloric acid) and kept under constant temperature water bath at 40-50 ℃ for 3 hours (capping). The principle of this process is that the catalytic performance of palladium particles is related to the aging temperature. It is known from practice that the best condition is 60 ℃± 5 ℃, and the heat preservation for 4-6 hours can not only improve the catalytic activity of palladium particles, but also prolong their service life.

C. Activation mechanism: the micelle structure of "colloidal palladium" is an electric double layer, and [pd0] m is a colloidal core. During activation, SN2 + is first adsorbed in the pores, and then the divalent tin ions are adsorbed to c1-1, forming the [nsn2 + · 2 (N-X) Cl -] adsorption layer, forming a colloidal group. Such micelles are negatively charged, and will not settle due to collision in aqueous solution. 2xcl-1 outside the adsorption layer is a diffusion layer.

D. Maintenance of activation solution: because the preparation of activation solution is complex and the cost is high, the following points should be paid attention to during use

In order to avoid bringing water into the activation solution, the following solution shall be treated for 2-3 minutes before activation: SnCl2 · 2h2o40g / L hcl100ml / L this process is called pre leaching, and then the activation treatment is carried out to filter the water dry.

The photographed substrate shall be cleaned repeatedly in the recovery tank as little as possible, and the water shall be used to supplement the consumption of the activation solution or to prepare a new solution.

After the activation solution is used for a period of time, when the delamination phenomenon is found, 10-20 grams of stannous chloride can be added per liter according to the actual capacity of the activation solution, and the delamination phenomenon can disappear.

When the temperature is lower than 15 ℃, the activation effect is poor, and heating shall be adopted. Water bath jacket is required for heating.

E. Degumming treatment: remove the excess residual activation solution to prevent it from being brought into the copper settling tank and causing solution decomposition. NaOH 50 g / L for 1.5 minutes.

Source: Copper micro media

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