Introduction of ink in PCB printing

Refers to the colored gelatinous substance used for printed boards. It is often composed of synthetic resins, volatile solvents, oils and fillers, desiccants, pigments and diluents. Often called ink.

(1) Composition of ink:

1. Resin: Resin is an important component that forms the ink film and determines the performance of the ink. Famous PCB ink brands have their own patented formulas. What we usually call the excellent performance of the brand’s ink. In fact, the resin plays a very important role in it. It determines the operability, gloss, adhesion, hardness, water resistance, solvent resistance, acid and alkali resistance, temperature resistance and so on of the ink.

2. Solvent:

The function of the solvent:

① Dissolve resin. Make it a good linking material;

②Dissolving pigments and additives;

③Adjust ink viscosity;

④Adjust the drying speed of the ink;

⑤ Dissolve and penetrate the substrate to enhance adhesion.

The solvent of the ink is not a single species and a single component. In consideration of solubility and drying speed, most of the solvents are mixtures. Different inks, different uses, have different solvents. So ink manufacturers have several different types of solvents. For one ink, only one or two types of solvents can be used. Generally speaking, for the same ink manufacturer, the resin system used in its research and development is basically determined.

Random use of diluents will lead to ink gelation (caking), peeling, uneven color, chemical resistance, thermal shock resistance, adhesion decline and other undesirable problems. No matter what kind of ink, it is incorrect to add “anti-white water” and “783” as a universal solvent.

3. Pigment: mainly use pigment. Pigments are classified by category and can be divided into organic pigments and inorganic pigments. Organic pigments refer to non-mineral pigments, which are brilliant in color and have a complete color spectrum, but usually have poor hiding power. Inorganic pigments refer to minerals. Such as: titanium dioxide, zinc white, iron blue, carbon black, etc., they have good covering power, strong light resistance and aging resistance, and PCB inks are mostly such inks.

In addition to being used as a colorant, pigments also play a certain role in the light resistance, heat resistance, flux resistance and chemical resistance of the ink.

4. Auxiliary: The purpose of adding auxiliary to the ink is to improve the physical properties of the ink, enhance the printing suitability of the ink, and improve the printing effect. Auxiliaries include: defoamer, dispersant, diluent, homogenizer, micronized amide wax rheology modifier suppliers,  firming agent, color separation inhibitor, precipitation inhibitor, plasticizer, coupling agent, ultraviolet absorber, catalyst, thickener, etc.