Spherical silicon micro-powder is mainly used for large-scale integrated circuit packaging, and also has applications in high-tech fields such as aviation, aerospace, fine chemicals, erasable optical disks, large-area electronic substrates, special ceramics, daily cosmetics and so on, with broad market prospects. Experts predict that by 20 10, the demand for spherical silicon powder in China alone will reach 20,000-30,000 tons, and the high-purity silicon powder will reach 654.38+10,000 tons, with an average annual increase of more than 20%. The global demand for spherical silicon powder will exceed 300,000 tons, worth tens of billions of yuan. With the rapid development of China's microelectronics industry, large-scale and ultra-large-scale integrated circuits require higher and higher packaging materials, not only ultra-fine, but also high purity, especially spherical particle shape. However, the preparation of spherical silicon powder is an interdisciplinary problem. At present, only a few countries in the world, such as the United States, Japan, Germany, Canada and Russia, have mastered this technology. As we all know, at present, spherical silica purchased in China mainly comes from Japan and South Korea, and imported spherical silica has high price and long transportation cycle. Domestic production of high-quality spherical silica has the advantage of localization and can completely replace imports.

Spherical silicon micro-powder is mainly used for large-scale integrated circuit packaging, and also has applications in high-tech fields such as aviation, aerospace, fine chemicals, erasable optical disks, large-area electronic substrates, special ceramics, daily cosmetics and so on. When it is used as filler in epoxy resin system, a lot of epoxy resin can be saved.

Main uses and properties of spherical powder

Why spheroidize? First of all, the surface fluidity of the ball is good, and it is evenly mixed with resin to form a film. The amount of resin added is small, and the fluidity is the best. The filling amount of powder is the highest, and the weight ratio can reach 90.5%. So spheroidization means that the filling rate of silicon powder increases. The higher the filling rate of silicon powder is, the smaller its thermal expansion coefficient is, the lower its thermal conductivity is, and the closer it is to the thermal expansion coefficient of monocrystalline silicon, the better the service performance of electronic components produced by this method is. Secondly, the spherical powder plastic packaging material has the smallest stress concentration and the highest strength. When the stress concentration of corner powder plastic packaging material is 1, the stress of spherical powder is only 0.6. Therefore, when packaging integrated circuit chips with spherical powder plastic packaging materials, the yield is high, and mechanical damage is not easy to occur during transportation, installation and use. Thirdly, the spherical powder has small friction coefficient, little wear on the mold and long service life of the mold. Compared with corner powder, the service life of the die can be doubled. The packaging molds of plastic packaging materials are expensive, and some of them need to be imported, which is also very important for packaging factories to reduce costs and improve economic benefits.

Spherical silicon micropowder is mainly used for packaging large-scale and ultra-large-scale integrated circuits. Whether spherical silicon powder is used or not depends on the integration level (the number of standard components in each integrated circuit). When the integration degree is 1M to 4M, the spherical powder has been partially used, and when the integration degree is 8M to 16M, the spherical powder has been completely used. At the level of 250M, the line width of the integrated circuit is 0.25μm, and at the level of 1G, the line width of the integrated circuit has been as small as 0.18μ m. At present, the CPU chip of the computer P ⅳ processor has reached this level. At this time, the spherical powder used is more advanced, which mainly uses the waste of polysilicon to make ethyl orthosilicate and silicon tetrachloride to hydrolyze to get silicon dioxide, and can also make spherical powder with adjustable particle size of-(10 ~ 20) μ m. The spherical silicon micropowder synthesized by chemical method is10 times more expensive than the spherical powder made from natural raw materials, because this powder is basically not polluted by radioactive alpha rays. The uranium content can reach below 0.02PPb. When the integration is high, the lead spacing between VLSI is very small. When the packaging material is radioactive, the integrated circuit will produce source errors, which will affect the reliability of VLSI, so strict requirements must be put forward for radioactivity. It is better when the natural seasonal raw materials reach (0.2 ~ 0.4) ppb. At present, the spherical powder used in China is mainly natural raw materials and imported powder. Integrated circuits are generally formed by etching circuits on monocrystalline silicon wafers, then connecting leads and tube corners, and then encapsulating them with epoxy plastic sealant. The closer the thermal expansion coefficient of plastic packaging materials is to monocrystalline silicon, the better the working thermal stability of integrated circuits. The melting point of monocrystalline silicon is 14 15℃, the expansion coefficient is 3.5PPM, the fused quartz powder is (0.3 ~ 0.5) ppm, and the epoxy resin is (30 ~ 50) ppm. When molten spherical quartz powder is added to epoxy resin in high proportion to make plastic packaging material, its thermal expansion coefficient can be adjusted to about 8PPM, and the more it is added, the closer it is to monocrystalline silicon wafer. Crystalline powder, commonly known as raw powder, has a thermal expansion coefficient of 60PPM and a timely melting point of 1996℃, which cannot replace fused quartz powder (i.e. fused silica micropowder). Therefore, when spherical powder is not used in high-end integrated circuits, fused angular silicon powder should also be used. This is also the reason why high-grade spherical powder can't be shaped into a nearly spherical shape with crystalline powder. Japan also walked this road in the 1980s, and the effect was not good. 10 years ago, including now, people in our country still took this road. From the above theory, it is proved that this method is not feasible. That is to say, high-grade plastic packaging powder cannot be replaced by crystalline powder.

Which is better to produce high-purity spherical quartz powder by melting or crystallization? According to experiments, experts think this problem is very clear. Spherical quartz powder can be prepared from natural silica by high temperature melting and spraying. A ball made of natural crystalline powder and then dispersed by plasma flame is a molten ball. The ball made of flame sintered powder has a smooth surface and a smaller volume, so it is better to use. The powder provided by Japan is completely flat by X-ray spectrum analysis, and it is also completely melted spherical quartz powder. However, domestic melting time, such as Lianyungang melting time spectrum analysis, the amorphous content is 95%, and the spectral line can still be seen, with a peak value of 5. Therefore, as long as the purity of spherical quartz powder can meet the requirements, it is best to use natural crystal as raw material, with the lowest production cost and simpler process route.