Why is surface modification necessary for non-metallic mineral powder used in copper-clad laminates?

Non metallic mineral powder materials are the main inorganic fillers in the copper-clad laminate industry, and manufacturers mainly choose the corresponding fillers based on the functionality of the copper-clad laminate. The commonly used inorganic fillers include talc powder, aluminum hydroxide, aluminum oxide, iron dioxide, silicon micro powder (silica), etc. Currently, the FR-4 copper clad laminate with high production mainly uses silicon micro powder as a filler.

In recent years, powder surface modification has been one of the active and rapidly developing technologies in the field of powder processing technology. The mechanism and methods of powder surface modification, surface modifiers, modification processes and equipment, surface modification process control, and product testing technology are all the main research directions.

The demand for powder in the copper-clad laminate industry is increasing year by year, and has become the fourth largest raw material. The functional requirements for powder in the copper-clad laminate industry are significantly different from those in industries such as coatings and rubber. The application trend of powder in the copper-clad laminate industry is mainly reflected in:

The particle size requirement is getting smaller and smaller;

The types of powders are increasing;

The functional requirements are becoming increasingly strong.

This places high demands on the modification technology of powders. How to further research on modification processes, modifier selection, modification equipment, process control, and product testing to meet the needs of the copper-clad laminate industry has become a research focus for powder processing enterprises.

There are many purposes for surface modification of powders, such as in coatings, inks, engineering plastics, rubber, packaging adhesives, etc. Each industry has different purposes and functions, but in the copper-clad laminate industry, there are mainly the following aspects:

1. Improving the dispersibility and compatibility of inorganic powders in organic material systems

During the process of crushing and destruction, inorganic minerals can disrupt their original crystalline state and cause partial bond breakage, resulting in the generation of new free radicals or ions on the surface of the powder, increasing the surface energy of the powder and easily causing agglomeration between powders, which is not conducive to the dispersion of the powder in resins and solvents.

The smaller the particle size, the greater the surface energy of the powder, making it easier to form clusters and increasing the difficulty of dispersion. Surface modification chemical reactions can be used to reduce the surface energy of powders, improve their dispersibility, and enhance their compatibility with resins.

2. Improving the activity of inorganic powders in organic material systems

After surface modification, the powder surface is coated with a layer of silane coupling agent, which forms stable chemical bonds with the surface of the powder. Some unreacted coupling agents are physically wrapped on the surface of the powder.

Due to the good compatibility between coupling agents and organic resins, which can lead to a decrease in the viscosity of the adhesive, the activity of the powder in the adhesive increases

On the one hand, it is convenient for customers of copper-clad laminates to adjust the characteristics of the adhesive solution to meet the requirements of the gluing process;

On the other hand, during the compression bonding of the semi cured sheet, the good mobility of the powder results in better uniformity of the cured sheet.

3. Enhance the interfacial bonding between inorganic powders and organic polymer materials

The free radicals or ions on the surface of the powder will form certain functional groups that react with organic matter under the action of water and air. For example, in common silicate materials, Si and Al easily form active functional groups such as Si OH and Al OH. These functional groups react with modifiers to form relatively stable chemical bonds such as Si-O-R and Al-O-R, which enable strong bonding between the powder and coupling agent. Another functional group of the coupling agent then combines with the organic resin to produce a relatively stable structure.

4. Improve certain characteristics of copper-clad laminates, such as hydrophobicity, heat resistance, etc

Choosing coupling agents with different functional groups can improve certain properties of copper-clad laminates, such as amino coupling agents that can increase the curing reaction of epoxy resins; Modifiers with hydrophobic groups such as alkyl groups can improve the moisture resistance of the board.

In short, due to the increasing demand for finer particle size, more diverse types of powders, and diversified functional requirements in the copper-clad laminate industry, surface modified powders have become a trend in their use.

At present, almost all powders with a particle size of less than 11 μ m that have emerged in the market are treated with surface modification, otherwise they cannot be stored and used well.