Silicon wafer manufacturers will gradually transition to diamond wire cutting

       Why are most mainstream manufacturers still using mortar wafer cutting instead of diamond wire cutting technology?

       Currently, the production of photovoltaic modules includes four key components: polysilicon production, ingot slicing, battery production and component production. This article will focus on the slicing process, which can be done in one or two processes.

       First, the production of primary polycrystalline silicon required for ingots (including square ingots and round bars) in the photovoltaic industry. Ingots consist of three key processes, and the ingots produced by each process have different qualities. Monocrystalline silicon is the purest of the three, higher cost, but also more efficient after being fabricated into a battery. Polycrystalline silicon is relatively more impurity, the cost is not high, and the efficiency is also general. There is also a new type of silicon called "single crystal", which is between the single crystal silicon and polycrystalline silicon, but has not been popularized.

       The slicing process is mainly to cut the polycrystalline silicon ingot into thin slices. Slicing is performed by passing a thin steel wire (SW) coated with silicon carbide and a slurry through a silicon ingot. The ingot is similar to the diamond wire (DW), but in this case, the diamond is attached to the cutting line by electroplating.

In recent years, the diamond wire is expected to replace steel wire and mortar slicing has been widely discussed, but there has been little substantive progress. In September 2012, the author participated in the EUPVSEC conference to find out why the technology was delayed, whether the market would turn to the diamond line, when this transition occurred, and to what extent.

In fact, all wafers are currently cut by wire technology. In the past decade or so, this process has hardly changed, and the opportunities to reduce costs and increase production efficiency seem to be minimal. In the past three to five years, with the expansion of industry scale and the pressure of cost growth, the industry has begun to seek alternatives to slicing tools.

Compared to steel wire technology, the gold-plated diamond wire has three key advantages: its cutting speed can be 2-3 times faster, and the machine productivity is increased by more than 1.5 times; the expensive and difficult-to-handle mortar is not used; the single-piece consumables are far lower.

Lack of economy

The conclusions presented in this paper are based on interviews with more than 50 market participants, including the world's largest silicon wafer manufacturers, equipment manufacturers, diamond wire and wire producers, and industry experts and analysts. Discussions have shown that, in fact, all large silicon wafer manufacturers are experimenting with diamond wire technology at different capacities, but there are few manufacturers operating in Japan except for Japan. Why is this?

There are two key factors. First, until recently, the economics of the Diamond Line was revealed. Although the diamond wire is more durable, it increases productivity and does not require mortar, but its unit price is too high. This difference was particularly evident 12 to 18 months ago: the price of the diamond wire exceeded $250-$300km, compared to the wire price of only about $1.28/km.

At present, the cost difference between the two has slightly narrowed. Because the proportion of diamond wire in the non-silicon processing cost (greater than 80%) is much higher than that of steel wire (30%), the price drop of the diamond wire has a greater impact on the total cost than the wire.

Although it is difficult to make a partial description of this change in a single production line, we generally think that instead of steel wire, switching to diamond wire can now reduce the cost by about $0.10 per piece (assuming the line is The diamond line is specially designed).
This will be a big absolute value. For example, for Jingao, its annual silicon wafer production capacity is about 2.4GW, and the potential profit after technological transformation can reach as high as 65 million US dollars per year. However, we will also discuss later, the current situation is that Jingao will only transform its single crystal and monocrystalline production capacity.

In addition, the market currently lacks the desire and capacity to capital expenditures. Switching to the diamond wire requires major refurbishment, in other words, the slicer needs to be replaced in most cases. For every $1 million machine, this will be a big expense. There is also a need to replace cleaning and etching equipment, which is another cash expense for battery manufacturers – different for different companies.

The business reality is that even if there is cash flow in the market, any technological transformation that requires such a large capital expenditure will face some lag. After all, manufacturers are waiting to prove the process and products.

Supplier risk

Another key factor limiting the replacement of the diamond wire is the deadline. Whether the diamond wire is an efficient cutting tool has not been proven. It causes a certain degree of disconnection during the slicing process and the downtime, which greatly offsets its production efficiency and cost advantages.

However, the diamond wire has been proven to be more efficient at cutting single crystals - as evidenced by Japan - it is now widely expected to perform on single crystals.

This makes the different silicon in the market become an important driving force for accepting the diamond wire, but predicting which kind of silicon will be favored by the market is a rough estimate. We agree that the market will favor the idea of ​​single crystal and monocrystalline silicon wafers. Compared with the current 40% market share, it is estimated that it will rise to about 60% by 2017 or 2018.

Another issue often mentioned by silicon wafer manufacturers is that if the industry makes technical changes to the diamond line, then whether the diamond line manufacturers can meet the demand. In general, this is not a problem. Although Asahi is currently the only manufacturer that can provide a high volume of commercial lines (we assume that its market share is greater than 60%), it is rumored that it still has a lot of idle capacity.

In addition, there are other Japanese manufacturers that can produce high-quality products that can expand capacity, including JFS, Noritake, Read, and ALMT. By 2014, the market will be more competitive. MeyerBurger, Switzerland, has a clear roadmap that will be a major player in this market regardless of the quality of its products.

Other European manufacturers, including Bekaert, SaintGobain, Schmid and Log-o-Matic, are potential entrants, as well as Chinese and Taiwanese manufacturers DIAT and MDWEC.

With the return of capital to the market, the adoption of the Diamond Line will really begin around 2014. We predict that by 2020, 69% of the wafers will be cut from the diamond wire, and the diamond wire will be used every year to 25 to 34 million kilometers.

As mentioned above, the diamond line is still an emerging market. We predict that its market share will not exceed 5%, and it will not change much until 2014. At that time, the capital expenditure budget will return to the current chaotic market, and the market will be quickly reversed.

We forecast that the market share of the diamond line market will reach 11%, 43% and 69% in 2014, 2017 and 2020, respectively. Most of the twisting will occur in the single crystal and monocrystalline markets, and by 2020, almost all diamond threads will be used. In contrast, we predict that the Diamond Line will account for less than 30% of the polysilicon market.

In the overall transaction period, under the dual drive of replacing the diamond wire and the potential PV market, it will lead to a significant increase in the use of diamond wire. According to forecasts, the global PV market demand for the Diamond Line in 2011 is about 300,000 kilometers (mainly in the Japanese market), reaching 2.7 million kilometers in 2014, about 11 million to 14 million kilometers in 2017, and 34 million kilometers by 2020. .

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