Introduction to diamond grinding wheel used in photovoltaic industry

Monocrystalline silicon and polysilicon

Silicon belongs to hard and brittle material, mohs hardness is 6.5, can make polycrystalline silicon, monocrystalline silicon according to the use.

Monocrystalline silicon (MONocrystalline silicon) is a relatively active nonmetallic element. With a basically complete lattice structure, monocrystalline silicon (MONocrystalline silicon) is a good semiconductor material with a purity of 99.9999%. It is mainly used for manufacturing semiconductor devices and solar cells.

Monocrystalline silicon  is usually manufactured by first producing polycrystalline silicon or amorphous silicon and then growing rod-like monocrystalline silicon from the melt by the direct pull or suspension zone fusion method.

Polycrystalline silicon  is a form of elemental silicon. When molten elemental silicon solidifies under the condition of supercooling, the silicon atoms are arranged into many crystal nuclei in the form of diamond lattice. For example, these crystals grow into grains with different orientations on the crystal surface, and these grains combine to crystallize into polycrystalline silicon.

Polysilicon is the direct raw material of monocrystalline silicon, and it is the electronic information basic material of artificial intelligence, automatic control, information processing, photoelectric conversion and other semiconductor devices.

It is called "the cornerstone of the microelectronics building".

Machining process

The processing process of monocrystalline silicon mainly includes: truncation, spherification, cutting, grinding, chamfering, grinding, chemical corrosion, polishing and other steps.

In contrast, polysilicon has no truncation and spherification steps and only needs to be cut square and sliced after the ingot preparation is completed.

In the whole preparation process of monocrystalline silicon and polycrystalline silicon from rod  to chip, diamond tools of different USES are required to participate in the processing, and the processing precision is relatively high.

Monocrystalline silicon rod grinding wheel

Single crystal roller grinding wheel, general size is 1A1 300*25 (35,40) *127*7, in the form of single chip and combination.

It is a composite grinding wheel with multi-granularity (D 120/140, 200/230, W40), which can achieve high machining efficiency and surface quality simultaneously.

Supporting machine tools include Wuxi on-machine WSK003, Wuxi open source WX-7321/2 and so on

Surface chamfering wheel

Chamfering of mono-crystal silicon grinding surface and polycrystalline silicon grinding surface also requires a large amount of diamond grinding wheel. The processing procedures are divided into coarse grinding and fine grinding, with the diamond particle size of 120/140, W40, W28, W20, etc. The main dimensions are 6A2 220*65*130*5*5, 6A2 200*60*80*5*5, 11A2 100*28(40)*31.75(20)*5*5, etc.

Domestic related machine equipment more, part of the surface chamfering all-in-one machine can be single polycrystalline arc or Angle, surface polishing.

Main supporting machine tools, grinding surface  : Wuxi Upper machine WSK-009, WSK-011, WSK-015, Wuxi open source WX-7422, etc.

Chamfering : Wuxi Computer WSK-007, WSK-013, Wuxi open source WX-7511, WX-7522, Shijiazhuang Weifeng, etc.

Conclusion

(1) As an "industrial tooth", diamond grinding wheel shows its superior performance more and more in many emerging industrial material processing fields. Especially in recent years, China has paid more and more attention to this strategic material.

With the improvement of raw material performance, serialization of product specifications, specialization of production equipment and standardization of testing means, diamond tools will develop towards a higher level, and product quality will be significantly improved.

(2) some high precision high precision diamond tools, such as photovoltaic industry ultrafine grain size of diamond grinding wheel, high precision bit of sapphire industry, high precision diamond grinding wheel, CMP dresser and so on, there is still a gap compared with foreign products, domestic products are mainly in the performance is bad or unstable, domestic large and medium-sized enterprises will be more willing to purchase expensive foreign products, to guarantee the quality of production.

This has also posed a new challenge to domestic relevant tool manufacturing enterprises, that is, to improve the product performance as much as possible and maintain the stability of the product performance under the condition that the precision of the product meets the use requirements.

(3) Domestic products should aim at high-grade and precise diamond tools. In the process of product production, strict product standards and technological procedures should be formulated to ensure the performance stability of the products;

In addition, it shall be equipped with high-precision CNC machine tools, electric spark, wire cutting and other equipment to carry out subsequent finishing and improvement of the products.

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