1. Specific application of silicon wafer production process

In the photovoltaic industry chain, diamond wire multi wire cutting machines are mainly used in two key links of silicon wafer manufacturing: silicon ingot square cutting and silicon wafer slicing. Silicon ingot square cutting is the process of cutting a grown single crystal silicon rod or polycrystalline silicon ingot in a specific crystal direction to form a silicon billet with precise dimensions; Silicon wafer slicing is the process of further cutting silicon billets into uniformly thick silicon wafers for subsequent battery cell manufacturing.

The application of diamond wire cutting technology in the production of photovoltaic silicon wafers has become very mature. By high-speed grinding (with a line speed of 1800-2200 meters per minute), diamond wires can reduce the thickness of silicon wafers to below 150 μ m, while reducing surface damage layers and improving silicon wafer yield. At present, diamond wire multi wire cutting technology has become the mainstream process for photovoltaic silicon wafer production, occupying over 90% of the market share.

In specific applications, diamond wire cutting technology exhibits excellent performance. During the cutting process, the diamond wire runs at an extremely high speed, and material removal is achieved through the interaction between diamond particles and silicon material. The cutting fluid system synchronously sprays cutting media containing polyethylene glycol and silicon carbide micro powder, achieving efficient cooling and abrasive delivery, significantly reducing silicon material loss and accurately suppressing subsurface damage.

2. Technical advantages and performance improvement

Diamond wire cutting technology has revolutionary advantages compared to traditional mortar cutting processes. Firstly, there has been a significant improvement in cutting efficiency, with the cutting speed increasing from 1-2mm/min in traditional mortar cutting to 5-10mm/min, a 5-10 fold increase. In actual production, when diamond wire cutting polycrystalline silicon wafers, the average cutting time per wafer is reduced by 30% compared to traditional methods.

Secondly, there is a significant improvement in material utilization efficiency. The loss rate of silicon material in traditional mortar cutting is about 40%, while diamond wire cutting can reduce the loss of silicon material to below 20% and increase material utilization by 15% -20%. This is mainly due to the narrower saw gap of diamond wire cutting. The saw gap width of traditional mortar cutting is usually between 350-400 μ m, while the saw gap of diamond wire cutting can be controlled within the range of 150-200 μ m.

The third is the comprehensive improvement of silicon wafer quality. The surface damage layer of silicon wafers cut by diamond wire cutting decreased from 20 μ m in mortar process to below 5 μ m, and the cutting surface roughness was less than 0.5 μ m. This not only improves the mechanical strength of the silicon wafer, but also facilitates subsequent battery manufacturing processes, significantly enhancing the photoelectric conversion efficiency of the battery.

The fourth is the improvement of the production environment. Traditional mortar cutting requires the use of a large amount of silicon carbide abrasive and cutting fluid, which not only incurs high costs but also generates a large amount of waste, putting great pressure on environmental protection. Diamond wire cutting completely abandons the mortar system and uses water-based cutting fluid, making the production process cleaner and significantly reducing waste disposal costs.

3. Market size and development trend

The photovoltaic industry is the largest application market for diamond wire multi wire cutting machines, accounting for 76.4% of the overall demand. According to the latest market data, the market size of China's solar photovoltaic wafer diamond wire saw will reach 4.73 billion yuan in 2024, a year-on-year increase of 18.5% compared to 2023, and is expected to increase to 5.68 billion yuan in 2025, a year-on-year increase of 20.1%.

From a global market perspective, the revenue scale of photovoltaic diamond wires worldwide is expected to reach approximately 17.72 billion yuan in 2024, and is projected to approach 81.26 billion yuan by 2031, with a compound annual growth rate of 22.8% from 2025 to 2031. According to QYResearch statistics, the global photovoltaic diamond wire market sales are expected to reach 82.17 billion yuan in 2031, with a compound annual growth rate of 24.3%.

On the demand side, the global demand for diamond wires in the photovoltaic silicon wafer field reached 81.6 million kilometers in 2021, and it is expected that the demand will reach 158.4 million kilometers by 2025. As the world's largest photovoltaic manufacturing base, China's demand for diamond wire exceeds 80% of the global total.

In terms of technological development trends, with the rapid development of N-type battery technology, higher requirements have been put forward for the quality of silicon wafers. The silicon wafers used in N-type TOPCon and HJT batteries are accelerating towards 130 μ m or even 120 μ m, which poses higher requirements for the wire diameter, tensile strength, and cutting stability of diamond wires. It is expected that by 2030, the proportion of products with a wire diameter of less than 30 μ m will exceed 60%. With the help of intelligent cutting equipment, the digital control of all elements of human machine, material, method, and environment will be achieved, promoting the reduction of cutting costs to below 0.03 yuan/W.

4. Application in the production of N-type battery cells

With the continuous advancement of photovoltaic technology, N-type battery technology is becoming the mainstream route for the next generation of high-efficiency batteries. Diamond wire cutting technology plays a key role in the production of N-type solar cells, especially in the two main technical routes of TOPCon and HJT.

In TOPCon battery production, the thickness requirements for N-type silicon wafers are more stringent. The average thickness of N-type silicon wafers currently used for TOPCon batteries is 165 μ m, and it is predicted to decrease to 155 μ m by 2025 and further to 145 μ m by 2030. Diamond wire cutting technology, with its high precision and low damage characteristics, can meet the strict requirements of TOPCon cells for silicon wafer quality.

HJT batteries have more stringent requirements for silicon wafers, not only requiring a thinner thickness (currently around 150 μ m, expected to decrease to 140 μ m by 2025 and 135 μ m by 2030), but also requiring the silicon wafer surface to have extremely high flatness and low damage layers. Diamond wire cutting technology can provide a surface roughness of Ra<0.3 μ m, fully meeting the production requirements of HJT batteries.

Another important application of diamond wire cutting in the production of N-type solar cells is half wafer and tile stacking technology. These advanced technologies require silicon wafers to have higher mechanical strength and more precise size control. Diamond wire cutting technology can significantly improve the yield and mechanical properties of silicon wafers by optimizing cutting parameters and tension control.

5. Comparative analysis with traditional mortar cutting

From the perspective of cutting principles, diamond wire cutting uses a fixed abrasive method, where diamond particles are fixed to steel wires through electroplating or resin bonding, while traditional mortar cutting uses a free abrasive method, where silicon carbide particles are suspended in the cutting fluid and driven by the high-speed motion of the steel wire to cut.

In terms of cutting efficiency, the speed of diamond wire cutting is 5-10 times that of traditional mortar cutting, mainly due to the advantage of fixed abrasives. More diamond particles are involved in cutting, and the mutual wear between abrasives is reduced.

In terms of material utilization, the advantage of diamond wire cutting is more obvious. Due to the narrower saw gap, more silicon wafers can be cut from the same length of silicon ingot. Taking a silicon wafer with a specification of 156mm × 156mm as an example, using traditional mortar cutting, a 1-meter-long silicon ingot can cut approximately 250 silicon wafers, while using diamond wire cutting can cut more than 300 wafers.

Cost benefit analysis shows that although the unit price of diamond wire is relatively high (about 10 times that of mortar steel wire), considering factors such as improved cutting efficiency, reduced material loss, and decreased subsequent processing costs, the comprehensive cost of diamond