What types of anti-corrosion inks are there?

Resist inks are inks that are resistant to chemical corrosion. Its function is to pre-print professionally on the part of the workpiece that does not need to be treated (corrosion, electroplating, welding, etc.) to form a corrosion-resistant (or electroplating-resistant, solder-resistant) film layer. Some inks need to be removed after processing, such as electroplating inks, etc., and some inks are not removed after processing, such as solder resist inks. These inks should have good image reproducibility, good printing suitability, good ink adhesion, large color difference from the color of the printing material to detect printing errors, can be removed with organic solvents or lye, and should not contain silk that can dissolve Net solvent and other properties. Representative inks include corrosion-resistant inks, plating-resistant inks, and solder resist inks used to make printed circuit boards.

1. Corrosion-resistant ink

Inks for corrosion resistance. The surface of the printing material is copper, aluminum, stainless steel and other metal plates. After printing the circuit diagram, it is generally used to corrode and remove the metal not covered by the ink with solutions such as ferric chloride, copper chloride, and sulfuric acid dumplings. Therefore, this type of ink should have The ability to resist the corrosion of these agents. After corrosion, it should be cleaned with 1%~3% dilute lye, or with organic solvents such as trichlorethylene to expose the original metal layer, so it is also required that the ink can be dissolved in the cleaning solution.

This kind of anti-corrosion ink uses pigments with a large contrast between the color and the printing material, such as carbon black, cyanine blue, titanium dioxide, etc., which are used for color development. Improve the printability of the ink and the properties of the ink film.

Rosin-modified maleic acid resin, alcohol-soluble phenolic resin, etc. are used as the linking material of the ink, and these linking materials are soluble in dilute lye. In order to dissolve these resins, solvents such as butyl cellosolve, butyl carbitol, and aromatic monsters are used.

The selected solvent should have a moderate volatilization speed. If it volatilizes too fast, it will easily cause pinholes. If it volatilizes too slowly, the ink will dry slowly and the acid resistance will decrease.

In addition, some auxiliary agents, such as silica, organic bentonite, plasticizer and paraffin, are added to the ink to improve the printability and adjust the viscosity of the oil plastic.

2. Resistant to electroplating ink

When making printed circuit boards, in the electroplating process, electroplating oil is printed on the parts that do not need electroplating. This type of ink includes solvent-based electroplating inks and W-type electroplating inks. The linking materials of the ink include vinyl chloride and vinyl acetate copolymer, chlorinated rubber, chlorinated polypropylene, phenolic resin, etc.

3. Solder resist ink

Solder resist ink is ink printed on circuit boards with lines and graphics. Its function is to prevent circuit corrosion, prevent insulation performance degradation caused by moisture, prevent solder from adhering to unnecessary parts, and prevent copper from being damaged by solder tanks. pollution etc.

The ink is required to have resistance to soldering, that is, under the action of solder at 240~260°C for 30s, the ink film shall not swell or peel off. The ink also needs to have solder resistance, and it should not be soluble in trichlorethylene and ethanol, which are used to clean circuit boards.

There are two types of solder resist inks: thermosetting inks (melamine resin and alkyd resin are used as linking materials, and epoxy resins can also be used as linking materials) and ultraviolet curable inks (acrylic polymer monomers are used as linking materials).

Melamine-alkyd inks have good printability and short hardening time, but formaldehyde is generated during hardening, and the coating film is not resistant to collisions. Epoxy resin ink has poor printability, drying is carried out by baking, and the coating film is not resistant to collision. The baking temperature is high and the baking time is long, but it has no odor, no harmful gas, and the coating film is firmly combined with the substrate. .

UV curable ink will not dry on the screen when printing, high printing precision, short hardening time (only a few seconds), and less temperature rise, so the shrinkage of the substrate is small, no bad smell, but it is difficult to print thick ink film and Highly concentrated tones that don't bond well enough to the substrate.