The emergence and development of printed circuit board (PCB) has brought great changes to the electronic industry. PCB has become an indispensable component of various electronic devices and instruments. With the continuous development of screen printing technology, new screen printing materials, screen printing technology and testing equipment for conventional pcb fabrication industry have been improved day by day, making the current screen printing technology adapt to high density PCB production.
The application of screen printing in conventional pcb fabrication mainly includes the following three aspects:
a. Application of PCB Surface Welding Resistance Layer;
b. Graphic transfer process of PCB and application of anti-corrosion and anti-electroplating;
c. Application of PCB Surface Marking Symbols.
Screen Printing Material
Screen is the most important component of screen printing plate, because it is the key to control the fluidity of ink and printing thickness. At the same time, it determines the durability of screen plate and the wide use in the quality switch manufacturing technology. In addition, the excellent combination of screen and screen photosensitive material is also an important factor in making screen printing plate with high quality and high precision. In order to ensure the good combination of screen and photosensitive material, the traditional method is to roughen and degrease the new screen, which can ensure the quality of screen plate and prolong the service life of screen.
2. Photosensitive Material for Printing Plate
Diazo photosensitizer and photosensitive film are commonly used in plate photosensitive materials. Diazo type photosensitive emulsion is widely used in screen printing. Photosensitive diaphragm has the characteristics of uniform and controllable film thickness, high resolution, high definition, abrasion resistance, strong adhesion with screen and so on, which has been widely used in printed board character printing.
Material and cross-section shape of mesh frame are very important. Compared with a certain size of mesh frame, if the strength of mesh frame is not enough, the consistency of tension can not be guaranteed. High tension aluminium mesh frames are commonly used nowadays.
4. Screen Printing Ink
There are generally three classifications of screen printing ink.
First, according to the types of printing products, it can be divided into: paper screen printing ink (usually directly using offset printing ink), plastic screen printing ink, fabric screen printing ink, glass screen printing ink, Ceramic Decal Screen printing ink and so on.
Second, according to the composition of the linking material, it can be divided into oxidized conjunctival drying resin material, volatile drying solvent ink, two-component reactive ink and UV curing ink.
Third, according to the special uses, it can be classified as: UV ink; light-emitting, fluorescent, light-storing ink; temperature-indicating ink, microcapsule ink (Braille, fragrance, foaming, etc.); liquid crystal, conductive, magnetic ink; pearlescent ink, anti-counterfeiting ink, etc.