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Spherical Silicon Powder for Microelectronic Packaging

wallpapers Industry 2020-11-05
Microelectronics Technology and the microelectronics industry represented by integrated circuits are the core and foundation of the information industry. At present, the world's microelectronics industry has surpassed heavy metals, automobiles, and agriculture to become the world's largest industry.
 
The three primary electronic packaging materials are substrate materials, plastic packaging materials, lead frames, and solders. Among plastic packaging materials, epoxy plastic packaging (EMC) is the mainstream of integrated circuit packaging at home and abroad. At present, more than 95% of microelectronic devices are epoxy plastic packaging devices. In EMC, the content of silicon powder accounts for 60% to 90%.
 
Silicon powder can be divided into two categories: crystalline and amorphous. Generally, integrated circuits are engraved on monocrystalline silicon wafers by lithography, then connected to lead wires and pins, and then packaged with an epoxy molding compound. In microelectronic packaging, amorphous or fused silica powder is mainly used, with a size in the order of micrometers. According to its shape, fused silica powder can be further divided into angular silica powder and spherical silica powder.
 
With the development of large-scale and very large-scale integrated circuits, the higher the degree of integration, the higher the silicon powder's purity in the epoxy molding compound, the finer the particles, and the better the spheronization. In particular, the requirements for the spheronization of the particle shape are put forward. Spherical silicon micro-powder should be used partially in large-scale integrated circuits. All spherical silicon micro-powders must be used in super-large and very large-scale integrated circuits when the integration degree exceeds 8M. This is because:
 
(1) The ball's surface has good fluidity, and it is uniformly stirred with the resin to form a film. The amount of resin added is small, the filling amount of powder can reach the highest, and the mass ratio can get 90.5%. Therefore, spheroidization means an increase in the filling rate of silicon powder. The higher the filling rate of silicon micro powder, the smaller the thermal expansion coefficient, and the lower the thermal conductivity, the closer the thermal expansion coefficient of monocrystalline silicon is. The better the performance of electronic components produced from that place.
 
(2) The plastic molding compound formed by spheroidization has the smallest stress concentration and the highest strength. When the stress concentration of the angular powder molding compound is 1, the spherical powder's stress is only 0.6. Therefore, when the spherical powder molding compound encapsulates the integrated circuit chip, the yield rate High, and it is not easy to produce mechanical damage during transportation, installation, and use.
 
(3) The friction coefficient of spherical powder is small, and the wear on the mold is little. Compared with the angular powder, the service life of the mold can be doubled. The price of the plastic compound's packaging mold is very high, and some still need to be imported. This is important to the packaging factory. It is also essential to reduce costs and improve economic efficiency.
 
The spherical silicon powder produced by the chemical method can reach 100% sphericity, spheroidization rate, and amorphous rate. It can get a shallow radioactivity index, but because of its low bulk density, when this kind of spherical powder is ultimately used When the epoxy resin molding compound is made, the compactness, strength, and linear expansion rate of the molding compound block are affected by it, so in actual use, it can only add 40% at most.


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