Microsilica powder (silicon dioxide powder) is an important basic raw material for the electronic information industry. It is non-toxic, tasteless, and pollution-free, and belongs to inorganic non-metallic materials. Microsilica powder can be divided into two categories: crystalline form and amorphous form. It must undergo special processing technology before it can be made into spherical microsilica powder that meets the requirements of electronic packaging materials.
General integrated circuits use photolithography to engrave the circuit on the single crystal silicon wafer, then connect the connecting leads and pins, and then encapsulate it with epoxy plastic compound. In the field of microelectronic packaging, amorphous or fused silica powder is usually used, and the size is on the order of microns. According to its shape, fused silica powder can be further divided into two types: angular silica powder and spherical silica powder.
With the rapid development of the electronic information industry, large-scale and ultra-large-scale integrated circuits have higher and higher requirements for silicon micropowder, not only requiring it to be ultra-fine, but also requiring it to have high purity and low content of radioactive elements, especially for particle shapes A spheroidization requirement is proposed. The higher the integration level of integrated circuits, the higher the purity of silicon micropowder in epoxy molding compound, the finer the particles, and the better the spheroidization. Spherical silicon micropowder should be partially used in large-scale integrated circuits, and in ultra-large-scale and ultra-large-scale integrated circuits , when the degree of integration reaches 8M or more, all spherical silicon micropowder must be used.
Why must use spherical silica powder?
(1) The surface of the ball has good fluidity, and it can be stirred with resin to form a uniform film. The amount of resin added is small, and the filling amount of powder can reach the highest level, and the mass ratio can reach 90.5%. Therefore, spheroidization means an increase in the filling rate of silicon micropowder. The higher the filling rate of silicon micropowder is, the smaller its thermal expansion coefficient is, and the lower its thermal conductivity is, the closer it is to the thermal expansion coefficient of single crystal silicon. The performance of the device is also better.
(2) The stress concentration of the molding compound formed by spheroidization is the smallest and the strength is the highest. When the stress concentration of the molding compound of the angular powder is 1, the stress of the spherical powder is only 0.6. High, and it is not easy to cause mechanical damage during transportation, installation and use.
(3) Spherical powder has a small friction coefficient and less wear on the mold. Compared with angular powder, the service life of the mold can be doubled. The price of the packaging mold of the plastic sealing compound is very high, and some need to be imported. This is very important for the packaging factory. It is also important to reduce costs and improve economic efficiency.