How to modify the surface of ultrafine silicon powder for copper clad laminate?

silicon powderSilicon micropowder has been used in copper clad laminates for more than ten years. Its surface treatment technology has always been a hot topic in the use of inorganic fillers in copper clad laminates. Through filler surface modification:
(1) It can interfere with the interaction between particles, effectively prevent particles from agglomeration, reduce the viscosity of the entire system, and increase the fluidity of the system;
(2) The compatibility of the particles and the resin matrix can be enhanced, so that the filler particles can be uniformly dispersed in the glue.

Generally speaking, the finer the particle size of silicon powder, the higher the specific molecular weight, and the lower the viscosity of the glue under the same filler addition. The more difficult it is to disperse, so it is particularly important for the surface modification of ultra-fine silicon powder.

Different from the conventional silicon fine powder with a fine particle size, the ultrafine silicon fine powder has a larger ratio of oil to oil, so the amount of modifier added should be exchanged accordingly. Conversion, ultrafine silicon fine powder oil absorption value penetration, not easy to disperse, should choose to reduce viscosity, improve dispersibility modifier.

The key to the surface modification of silicon micropowder is: how to disperse the modifier uniformly on the particle surface, and at the same time ensure the chemical bonding conditions between the modifier and the particle surface. Dispersion on the surface of the particles is a problem that interferes with the production of silicon powder.

Because the dry process is relatively simple and the production cost is relatively low, at present domestic silicon micropowder surface modification basically adopts this process. It is dispersed on the surface of the particles, so the effect of dry modification is relatively poor.

Wet modification is carried out under liquid phase conditions. The modifier can disperse the particle surface relatively uniformly. Generally speaking, the modification effect is better. However, the wet modification process is complicated, requiring drying and depolymerization processes, and the production cost is relatively high. High, but the effect of wet modification is better.

Dry powder modification is generally recommended for silicon powder for conventional copper clad laminates, and it has been verified that the dry modified products are on the fillers used in aluminum-based copper clad laminates. For 8μm cutting (large particle cutting point, the same below) and 6μm cutting, the dry process is recommended for comprehensive cost and performance considerations. For 5μm cutting and below products, the wet process is recommended. For finer products, surface modification has been carried out using gas-phase synthesis.



Source: Sun Xiaoyao. Technical progress of ultrafine silicon powder for copper clad laminates [C]. Proceedings of the 19th China CCL Technical Seminar, 2018.

Post time: May-22-2020
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