The Copper Sulfate is widely used in industrial production and is a chemical process that has existed for more than 100 years. All kinds of products around us, such as: hardware furniture, lighting, electrical appliances, digital products, jewelry, etc. have experienced the process of the copper sulfate .
Therefore, the copper sulfate is a very important chemical process. The important feature of the acid copper is that the plating solution contains sulfuric acid and copper sulfate, and the s are plated with a metallic copper layer.
In recent decades, the research on the copper sulfate has focused on the development of plating solutions and light agents: while the anode and copper ion supplement research is relatively rare. In the following, the author combines more than 10 years of work experience to introduce the production process of the most commonly used copper sulfate anode-phosphorus copper, and also discusses some insoluble anodic acid copper system.
02
Copper Sulfate Soluble Anode – Phosphorus Copper
Copper sulphate , widely used in hardware decoration and printed circuit board (PCB) industry, the anode of these process is mainly based on phosphor bronze. Phosphorus copper is added 0.025%-0.065% phosphorus in metallic copper.
Phosphorus Copper continuously electrolyzed a large amount of Cu and a trace amount of Cu3P, while Cu entered the plating solution to supplement the copper ions, Cu3P became a dark brown anode mud deposited on the bottom of the anode bag, and the cathode was coated with bright metallic copper. The process reaches a balanced state by adjusting the parameters.
Phosphorus copper was first proposed by NeversIi-2] in the United States in 1954. In the second or third year after the second year, the industrial production of phosphorous copper in the United States was extensively used in the copper sulfate industry.
Phosphorus copper production technology entered China in the early 1990s and blossomed throughout the past 20 years. At present, among the phosphor bronze used in the printed circuit board industry, Chinese manufacturing has accounted for more than 70% of the world’s production.
The large-scale production of phosphorous copper has been in the country for more than 20 years. In these years, the manufacturing process of phosphor bronze can be roughly divided into three stages.
Stage 1. In the early 1990s, the production method of phosphorus copper was horizontal continuous casting. The pellets were cleaned and packaged. Horizontal continuous casting. It is based on the copper horizontal continuous casting process, and this process has many shortcomings:
(1) The energy consumption is large, and the power consumption per ton of phosphor bronze is more than 500 kWh.
(2) The output is low. Because it is a batch production method, the primary molten copper is only about 2 tons. After the discharge, it needs to be reheated and the production capacity is low.
(3) The phosphorus content is difficult to control, because at that time, the horizontal continuous casting used in the horizontal continuous casting furnace, the phosphorus element is easily volatilized, and the uniformity in the copper solution is poor.
In the first few years of the introduction of phosphorous copper production technology, its batch molding products only have cylindrical phosphor bronze particles of 025mm~25mm. At present, some hardware manufacturers are also using them.
Phosphorus copper particles have obvious shortcomings in the process, such as:
(1) It is easy to play a role of “bridge” in the course of the .
(2) Dissolution unevenness during use. It is difficult to predict and calculate the specific surface area and the amount of copper ions added, resulting in an imbalance of copper ions in the plating solution.
(3) Phosphorus copper particles need to use lubricating oil during shearing to increase the strength of subsequent product cleaning and the pressure of sewage treatment.
Phase II. With the great development of the PCB industry and the hardware in China, the early stage phosphorus copper manufacturing process cannot meet the requirements for use.
Therefore, in the early 21st century, the production technology of phosphor bronze ushered in the first big leap.
The production process of phosphor bronze changed to: continuous casting, mechanical molding, cleaning, packaging. The upper lead casting is a phosphorus copper casting process that is still popular today. The advantages of this process are obvious:
(1) Low energy consumption, the power consumption per ton of phosphorus copper is below 320 degrees. With the increase of single furnace output and the improvement of crystallizer, the energy consumption is still decreasing.
(2) The output is high. Because it is continuous production, the power parameters can be adjusted according to the requirements. The output can be adjusted and controlled. The basic daily output of the upper furnace for producing phosphorous copper is above 20 tons.
(3) The low work intensity, thanks to the advantage of continuous production of the upper process, the work of the workers is an average continuous process, so the work intensity is greatly reduced.
(4) Control the stability of phosphorus. The upper induction furnace is a closed system. The copper water is not exposed. The convection in the furnace is strong. After adding phosphorus, it will spread and evenly distribute in the furnace. At the same time, when the copper water is led out of the furnace, Immediately cool the crystal, not in contact with the air, and there will be no loss of phosphorus.
(5) The quality of the copper rods cast on the upper lead is good, which is conducive to the subsequent processing of the dead sequence.
In addition to the improvement of the casting process, the mechanical processing of phosphor bronze has also been upgraded, not only to produce phosphor bronze, but also to produce phosphor bronze balls.
At that time, the production of phosphor bronze balls were small and large-size products, small-sized phosphor bronze balls were 31 mm and below, and large-size phosphor bronze balls were 31 mm or more, and the largest size was 55 mm.
The small-sized phosphor bronze ball is made by a cold heading process: the large-sized phosphor bronze ball is produced by a pressing process. The process of cold heading and pressing can be adapted to the production needs of the time, but there are some disadvantages.
The cold heading process uses a large amount of fuselage lubricating oil and product release oil, and some oil stains are brought into the product, resulting in high-strength copper ball cleaning and sewage treatment work:
At the same time, the cold-rolling process is used to cast copper rods, and the surface of the copper balls produced by the tantalum is rough, and there are obvious equatorial rings, which affect the calculation of specific surface area and the degree of uniform dissolution in the ;
In addition, the output of the tanning system is only about 2.3 tons per machine per 8 hours, which is noisy during production. The pressing process produces large-size phosphor bronze balls, which are pressed by a vertical press and trimmed one by one with a lathe to achieve a relatively good spherical shape.
At that time, the pressing process was mainly based on manual pressing, and the risk was great: Moreover, the production of each machine in the pressing process was only about 2 tons per 8 hours, and the output was low: and, in order to obtain a better spherical shape, it was necessary to configure personnel. The trimming operation greatly increases the work intensity and personnel input.
Therefore, these two machining methods must be improved in the future. In order to achieve a better anti-oxidation and brightening effect, the cleaning of phosphor bronze begins to introduce copper brighteners and antioxidants. However, these things are not publicly available and cannot be applied to the , so there is a great potential risk to downstream, especially PCB users.
Stage 3: Due to fierce competition in the industry, in the first decade of the 21st century, the technology of various manufacturers continued to evolve, and the production of phosphorous copper had a big leap a few years ago.
At this time, the production process of phosphor bronze is adjusted to: continuous casting, microcrystalline processing, mechanical processing, cleaning, packaging. The technical focus of this leap is microcrystalline processing, which has undergone several years of research and development, including the creation, industrialization and marketization of microcrystalline processes.
The microcrystalline process achieves the following advantages by refining and optimizing the phosphor bronze metal crystal:
(1) Under the effect of the same , less phosphorus is incorporated, and the phosphorus content decreases from 0.04% to 0.065% to 0.025% to 0.05%.
(2) The phosphorous film produced by Phosphorus Copper during the process is thinner, denser and stronger.
(3) The utilization rate of phosphorus copper is higher. According to a large number of statistical data of many manufacturers, the utilization rate of phosphorus copper can be increased by more than 3%.
(4) Producing less anode mud, which is one-fifth of the original, reducing the frequency and time of cleaning the tank and anode bag to save manpower and resources.
(5) In the course of the , the quality of the s can be effectively improved, especially in the field of high-end PCBs.
(6) Since the plasticity is enhanced after microcrystallization, it is advantageous for subsequent mechanical forming processing. With the development of microcrystalline technology, the mechanical processing of phosphor bronze has also developed. The molding of small-sized phosphor bronze balls has been changed to be mainly oblique rolling. The advantage of cross-rolling is that water is used instead of lubricating oil for lubrication and demoulding. Reduce the pollution caused by the use of lubricating oil;
At the same time, the surface of the phosphor bronze ball produced by the cross-rolling process is smooth: roundness is sufficient; 118 stocks are low and can be copied in large quantities; the output of each machine is more than 4 tons in 8 hours.
The production of large-size copper balls is processed by cold heading process, and the more backward pressing process is eliminated. The benefits are sufficient:
(1) The output is large, and each machine can produce more than 15 tons of 55mm phosphor bronze balls every 8 hours.
(2) It is convenient to change production. It only needs to change a set of molds.
(3) The operator has low work intensity, and one person can operate one 118 library.
In the aspect of product cleaning, in order to prevent unnecessary risks to customers and reduce the intensity of sewage treatment, the process of using brighteners and antioxidants is eliminated, only weak acid deoxidation layer, weak alkali neutralizing residual acid, and polishing process Improvements to avoid problems such as oxidation of the copper ball.
Today, the process of upgrading copper phosphate is still in progress. At present, the continuous casting process of the upper lead is developed towards a larger output and a higher degree of automation, which can further reduce energy consumption, reduce labor intensity and save manpower.
Mechanical forming is carried out in the direction of rolling large-size copper balls, thereby reducing the use of lubricating oil and mold release oil, reducing the risk of unfriendly to the environment, making the whole production greener and lower carbon. Cleaning and packaging are also moving towards full automation and refinement.
03
Introduction of Copper Ion Supplement System of Insoluble Aluminium Sulfate
The Copper Sulfate has an insoluble anode system in addition to a soluble anode system.
The insoluble anode system uses an anode made of an inert material, mainly lrO2/Ti. During the process, the anode does not lose mass, and the copper ions in the plating solution are supplemented by other means.
In the of the PCB industry, one of the complementary forms of copper ions is supplemented with high purity copper. The characteristic of the process is that a conventional copper tank is suspended in the slot, and the two forums of the forum solution are continuously circulated. The reaction between the dissolved copper tank and the electrolytic tank is:
Molten bath: 2Fe + cu-Cu + 2Fe
Electrolytic tank: anode: Fe2 – Fe3 + e
Cathode: Cu+2e_÷Cu; Fe3+e-Fe2
In the above reaction, the copper-soluble tank continuously converts the copper metal into copper by the ferric iron. After the liquid enters the tank, the main reaction of copper plating is performed on the cathode , and a small amount of ferric iron is converted into the second price. The side reaction of iron; while the reaction of divalent iron to ferric iron is carried out on the anode, the ferric iron is circulated into the copper-dissolving tank to continue to dissolve copper, and the whole system reaches a benign circulation balance. When the amount of copper is insufficient, only High-purity copper is added to the copper bath.
Compared with the traditional process, the advantage of this process is that there is no need to exclusively use phosphor bronze or anode mud. The coating quality of the is good. In my opinion, this process is not limited to use in the , but also as a good way to recycle copper resources.
For example, the copper-clad headstock produced in large quantities in the PCB industry is a two-sided sticky copper foil with a scrap of epoxy resin insulation.
At present, the treatment of such waste is: crushing, washing and flotation. The copper-containing material is smelted into copper ingots and electrolyzed with copper.
The disadvantages of this type of processing are obvious: (1) There are four cumbersome steps.
(2) A large amount of hazardous waste is generated when it is broken – epoxy resin powder.
(3) A large amount of harmful toxic fumes need to be treated when smelting copper ingots.
If it is recycled by the above method, it can be placed in one step, and only a large enough copper bath is needed to put the waste into the copper bath. When the copper is completely dissolved, the epoxy resin sheet can be taken out.
The epoxy resin sheet can be made into various insulating gaskets, and the cathode is plated with high-purity cathode copper for recycling.
Insoluble Aluminium Sulfate , in addition to the use of high-purity copper as a supplemental source of copper, copper oxide powder is also used as a supplement source in the PCB industry, and concentrated in some high-demand applications.
This form of the system is also composed of a copper-dissolving tank and a 118-chamber tank, and the dissolution tank is added with copper oxide powder. The reaction between the dissolution tank and the electrolytic cell is:
Copper bath: CuO+2H-Cu+H20
Electrolyzer: Anode: 2H2O-O2+4H
Cathode: Cu+2e-Cu
In this reaction, the copper-soluble tank turns the copper oxide into copper ions by the sulfuric acid in the plating solution, and after the liquid enters the tank, the copper plating reaction is performed on the cathode: the oxygen generated on the anode is discharged, and the hydrogen element and the plating liquid are The sulphate is combined to form sulfuric acid again, and the plating solution continues to circulate to dissolve the copper oxide powder in the copper lysing tank, and the whole system reaches a cycle equilibrium. This kind of supplementary form does not produce anode mud, the speed of copper dissolution is fast, the quality of plated parts is good, and it has certain advantages;
However, this process requires the use of copper oxide powder, and the high-quality copper oxide powder has a high production cost; compared with pure copper, the same quality copper oxide powder can only produce 80% of copper ions of pure copper, so it is not available in the market. Promotion.
Similarly, this processing method can also be used as a method for resource recycling, which can specifically recover metal oxide resources, such as: recovering metal resources of spent metal oxide catalysts; recovering low-level metal oxide powder resources, etc. .
04
in conclusion
As a production worker of phosphorus-phosphorus anodes, I hope to make a summary of the development of phosphorus-phosphorus anodes in China in the past 30 years. At the same time, we explored some other processes and proposed new ideas and methods for solving problems in related industries.