1. Diamond wire is mainly used in the photovoltaic industry
The current mainstream process is electroplating diamond wire, which is to coat a layer of diamond powder on the metal wire to cut hard and brittle materials such as photovoltaic crystal silicon, crystal, magnetic materials, sapphire, etc. In recent years, diamond wire cutting technology has played an important role in the cutting industry. It plays an important role, and its application range is also extremely wide. It is mainly used in the current hot photovoltaic field, such as in the manufacture of silicon wafers, for cutting silicon rods, cutting squares, and slicing silicon wafers. The demand for silicon wafer cutting diamond wire accounts for more than 90% of the total demand.
2. Advantages of diamond wire
Diamond wire was mainly used in the field of sapphire at the earliest, and it began to be applied in the photovoltaic field in 2015. Before photovoltaics were cut by mortar. When the Chinese people developed the mortar cutting technology to the extreme, there was no room for "cost reduction", and the diamond wire technology entered the field of vision of photovoltaic people.
What are the advantages of diamond wire?
1. It can realize high-speed cutting. Compared with the traditional mortar cutting method, the speed is increased by 2-3 times, and the time-consuming is greatly reduced;
2. The traditional mortar cutting environment is harsh and not environmentally friendly, and a large amount of mortar needs to be recycled, which consumes a lot of manpower and financial costs. However, the diamond wire process does not require mortar, only water or water-based cooling cleaning fluid is needed. Yes, so diamond wire cutting has the advantages of environmentally friendly production and manufacturing;
3. The loss of silicon material is smaller than that of traditional cutting, and the overall cost of wire consumption is low;
4. The diameter of diamond wire can be adjusted, and different wire diameters are used for different materials, which greatly reduces the consumables and cutting accuracy;
5. Space saving, the diamond wire cutting machine occupies a small space, which can save a lot of space.
3. Technological innovation and challenges faced by diamond wire
For the photovoltaic industry, reducing costs and increasing efficiency is an eternal topic, especially in the past two years when the price of silicon materials has soared and swallowed downstream profits. How to reduce cutting losses and reduce the cost of silicon wafers is an urgent need for silicon wafer companies to solve.
1. The inevitable result of silicon wafer thinning is the thinning of diamond wires
Wafer thinning is the direction of the silicon wafer industry's efforts to reduce the cost of a single wafer in the past two years. Accompanied by the thinning of silicon wafers is the thinning of diamond wires.
Advantages of thinning lines
(1) Diamond wire thinning can reduce the loss of silicon during cutting. During the slicing process, the fragmentation rate of silicon wafers is reduced to improve the yield of silicon wafers. The high price of silicon material promotes the reduction of diamond wire diameter and reduces silicon consumption, which is the most direct and effective benefit.
(2) After the diamond wire is thinned, it can cut thinner silicon wafers. It's like cutting vegetables with an ax and cutting vegetables with a kitchen knife. Both of these reasons help to cut the same length of silicon rod into a greater number of silicon wafers.
(3) After the diamond wire is thinned, the amount of busbar material will be greatly reduced. As the diameter of the wire becomes smaller, the cross-sectional area becomes smaller, and the mass of the busbar becomes smaller, which shows that there is a saving in materials.
Downsides of Thinning Lines
(1) The thinner the wire, the more difficult it is to process the busbar drawing, nickel plating, and diamond powder application, and more cost is required;
(2) The thinner the wire, the smaller the pulling force, the cutting speed and efficiency will be reduced, and time cost is required;
(3) The thinner the wire, the smaller the diameter, and the smaller the amount of diamond powder attached to the same length. Cutting the same silicon wafer requires a longer diamond wire;
(4) The thinner the wire, the easier it is to break under the same material, and the slicing process requires multiple wires to work together, and the wiring after the wire breaks takes a long time.
2. The busbar is facing the challenge of replacing the diamond wire itself and the tungsten wire itself.
Although the cost of steel wire is lower than that of tungsten wire, the problem is that the breaking force is lower than that of tungsten wire, and the current 38-42 micron is close to the limit of steel wire. Tungsten wire substitution has become a new direction.
Comparing steel wire and tungsten diamond wire from the perspective of service life, the usage times of tungsten diamond wire is 10-20 times that of steel wire. But the disadvantages are: first, the price of tungsten is higher than that of steel wire, and the price of tungsten wire of the same length is several times the price of steel wire; second, the winding length of tungsten wire is at most 100km, while steel wire can reach 300km, so transportation and use The cost is also higher than that of steel wire; third, the yield of the current tungsten wire busbar is lower than that of steel wire, thus increasing the cost of tungsten wire
Therefore, there are both advantages and disadvantages of diamond wire thinning and busbar replacement, and trade-offs are required.
From the perspective of historical development, the threshold for diamond wire is relatively low, which has also resulted in fierce competition for diamond wire for a period of time. At this point in time, we believe that the technology and production of diamond wires are being comprehensively improved. The development of wire thinning is accelerating, and at the same time, under the bottleneck of traditional high-carbon steel wire thinning, the busbar material is facing the possibility of replacement. Coupled with the continuous trend of large size and thinning of silicon wafers, the technical barriers of diamond wire are expected to be strengthened. In terms of production and manufacturing, leading enterprises have stepped up the transformation of one machine and multiple lines to greatly improve production efficiency.
4. Annual Demand Outlook for Diamond Wire
The profitability of diamond lines in the photovoltaic industry chain is at the forefront. In 2021, the profit rate will be second only to silicon materials. The average gross profit rate will reach about 35%, and enterprises that extend upward to the busbar or further upstream can reach more than 50%.Thinning, thinning and large size are expected to increase the wire consumption of the slicing process. In terms of downstream demand, under the background of grid parity and carbon neutrality, the demand for photovoltaics has increased, and the expansion of superimposed silicon wafers has accelerated, making the demand for diamond wires expected to exceed industry growth.
As the industry structure tends to stabilize, the price of diamond wire has gradually stabilized, and the thinner wire may bring a certain possibility of price increase. According to estimates, in 2021, the diamond wire consumed per GW will consume 340,000 kilometers, and in 2022, the diamond wire consumed per GW will reach 500,000 kilometers.
It is estimated that by 2025, the market space for diamond wire in the photovoltaic field will reach more than 15 billion, and the compound growth rate will be more than 40% from 2021 to 2025.