Application of laser particle size analyzer in silica powder particle size detection（2）

3. Particle size control of silica powder

With the rapid development of my country's microelectronics industry, national defense industry and other high-tech industries, it is required that microsilica powder must meet the requirements of high purity, ultra-fine and spherical shape. Therefore, the processing process of microsilica powder must meet the pollution, particle size control, purity control, radioactivity Issues such as element control need to be strictly controlled.

Microsilica powder can be classified according to different standards, and its particle size has become an important indicator of its quality. By use, microsilica powder can be divided into: microsilica powder for paints and coatings, microsilica powder for epoxy floors, microsilica powder for rubber, microsilica powder for sealants, microsilica powder for electronic and electrical grade plastic sealing materials, and precision ceramics. Microsilica powder. The particle size requirements of silica powder for different uses are also different. For example: Silica powder for paints and coatings, mesh size: 600-2500 mesh. Silica powder for epoxy flooring, mesh size: 600-1250 mesh.

By grade, silica powder can be divided into: ordinary silica powder, electrical grade silica powder, electronic grade silica powder, fused silica powder, ultrafine silica powder, and "pellet" silica powder. The particle size requirements for silica powder are different in different grades. Among them, "pellet" silica powder is made of high-quality quartz raw ore, with a fineness between 325 mesh and 5000 mesh, with a reasonable and controllable particle size range, and the appearance is White powder.

4. Sphericity detection of silica powder

Spherical silica powder is mainly used for large-scale integrated circuit packaging. It is also used in high-tech fields such as aviation, aerospace, fine chemicals, rewritable optical discs, large-area electronic substrates, special ceramics and daily cosmetics. It is used in epoxy resin systems After being used as a filler, a large amount of epoxy resin can be saved.

Why should microsilica powder be spherical? First of all, the surface fluidity of the ball is good, and the film is formed evenly when mixed with the resin. The amount of resin added is small, and the fluidity is the best. The filling amount of powder can reach the highest, and the weight ratio can reach 90.5%. Therefore, spheroidization means an increase in the filling rate of silicon powder. The higher the filling rate of silicon powder, the smaller its thermal expansion coefficient, the lower the thermal conductivity, and the closer it is to the thermal expansion coefficient of single crystal silicon. The electronic components produced thereby The performance of the device is also better.

Secondly, the stress concentration of the molding material made by spherical powder is the smallest and the strength is the highest. When the stress concentration of the plastic molding material of the angular powder is 1, the stress of the spherical powder is only 0.6. Therefore, when the integrated circuit chip is packaged with the spherical powder molding material, the yield rate is reduced. High, and it is not easy to cause mechanical damage during transportation, installation and use.

Third, the friction coefficient of spherical powder is small, and the wear on the mold is small, which makes the mold have a long service life. Compared with angular powder, it can double the service life of the mold. The price of plastic packaging molds is very high, and some It also needs to be imported, which is also very important for packaging factories to reduce costs and improve economic benefits.

Particle sphericity is one of the basic parameters of particles. The size of sphericity directly affects the fluidity and packing properties of particles. At present, the detection of sphericity mainly relies on microscopes.

5. Application of laser particle size analyzer in silica powder industry

In the preparation and application process of spherical silica powder, the detection of sphericity and particle size is crucial. Microscopic image particle analyzer, which uses image acquisition and analysis software, perfectly combines the computer with particle size and particle shape analysis theory, and can obtain the particle image while simultaneously analyzing the particle size, sphericity, aspect ratio, and bulk ratio of the particles. Characteristic parameters related to particle size and shape such as , surface, etc. are presented in the form of characteristic values and distributions. Winner99E was used for this silica powder test. The test instrument is as shown below: