And what process are these colors applied to the PCB? The answer is the solder mask process, and the traditional solder mask process includes spraying, coating and silk screen printing.

Then let's talk about silk screen printing in detail.

The full name of silk screen printing refers to screen printing. Compared with spraying and coating, silk screen printing has higher ink uniformity and precision on the surface of PCB. Therefore, on some high-standard circuit board products, most of them are made by silk screen printing. Solderproof process. Silk screen printing has irreplaceable process advantages and cost advantages. An ordinary semi-automatic screen printing machine only needs tens of thousands to hundreds of thousands of equipment costs, is simple to operate, takes up less space, and can meet very good quality requirements.

What is the purpose of the solder mask process?

As the mother of electronics, the circuit board is inseparable from all electronic products and mechanization. So in such a highly integrated and high-precision electronic environment, how to ensure that the PCB circuit is not short-circuited, oxidized, or scratched? How to protect the circuit from short circuit when the PCB goes through wave soldering? At present, PCB has higher and higher requirements for stability. After years of development and progress of PCB, the mature PCB process incorporates the solder mask process into the fixed process of PCB process, and covers a layer of ink on the surface of the PCB to form a protective layer, which is effective Cutting off the direct contact between the air and the copper surface circuit greatly protects the integrity of the PCB circuit and reduces the risk of short circuit and short circuit.

So, what are the processes of anti-soldering?

1. Pre-treatment for welding resistance: pickling - water washing - frosting - medium pressure washing - ultrasonic washing - air drying - drying.

2. Screen printing (screen printing): Ink mixing-screening-printing-board receiving.

3. Pre-baking: drying the printing ink to make it semi-cured.

4. Exposure: align the film and PCB, and fix the ink pattern.

5. Development: Dissolve the ink other than the ink pattern with weak alkali.

6. Post-baking: The ink is completely cured to complete the solder mask process.

So, let’s take a closer look at the process of screen printing: Facing the increasingly high requirements of PCB manufacturing process, the solder mask process is also gradually updated. At present, there are many types of screen printing equipment for solder mask process, mainly for different process requirements. .

According to the degree of automation, it can be divided into: semi-automatic screen printing machine and fully automatic screen printing machine . At present, the semi-automatic screen printing machines in the industry include: semi-automatic oblique arm screen printing machines, which are mainly used for plugging holes in the solder resist process. With stable downforce, simple structure, and convenient operation, the plug hole work is well completed.

Semi-automatic vertical screen printing machine, this type of machine is mainly used for printing oil on the surface of solder resist process. Its advantages are high efficiency, quickness and simplicity, and it can be well completed in terms of precision and higher-demand stop printing.

Semi-automatic double-table screen printing machine, which combines the advantages of the above two machines, and increases the table to upper and lower double tables, which greatly improves production efficiency. At the same time, the four-column lifting structure also inherits and optimizes the stability of the inclined arm type. , so its versatility is very wide.

Faced with the demand for more and more advanced intelligent chemical factories, a fully automatic screen printing machine has also appeared in recent years. This machine has been updated and improved in combination with all semi-automatic equipment based on years of deep cultivation of the solder mask process. Industrial camera, servo drive, human-machine interface, automatic loading and unloading and other functions can realize the future industrial trend of full automation of unmanned factories. For the sake of PCB customers, equipment manufacturers save site costs for customers, connect loading and unloading, printing and baking in series, and design and develop a one-stop production process: a fully automatic three-machine connection screen printing machine was born. It is connected by a plug hole screen printing machine and two ink screen printing machines, and at the same time, it takes into account all the printing work of solder mask. While the efficiency is improved, the failure rate is also greatly reduced. This kind of equipment is used in major manufacturers to protect PCB and make an indelible contribution to Industry 4.0.