Application of high-precision thick film screen printing process in surface metallization of ceramic dielectric filters

Ceramic dielectric filter is a filter based on ceramic materials. As an important part of radio frequency devices in mobile communications, it is responsible for filtering sent and received signals, that is, it can selectively transmit or block specific frequency ranges. signals to ensure the accuracy of sending and receiving signals.With the advent of the 5G era, ceramic dielectric filters have gradually become mainstream applications because they can meet the development trend of miniaturization and low cost.However, its process is not yet fully mature. Today we will take a look at the key link of ceramic dielectric filters: ceramic metallization process.
1. Ceramic dielectric filter production process
The production process of ceramic dielectric filters mainly includes powder manufacturing, press molding, sintering, grinding, metallization, assembly and debugging, etc. The metallization process accounts for 35% of the entire process and is a key link in the production of ceramic dielectric filters. .
2. Ceramic dielectric filter metallization process
Ceramic metallization is to make the insulating material of ceramic conductive. By coating silver paste on the front and back of the ceramic substrate, it is polarized by DC high voltage to produce a piezoelectric effect, thereby shielding electromagnetic waves.The better the conductivity, the better the shielding effect and the smaller the insertion loss.Therefore, in order to ensure conductive performance, silver paste coating plays a key role in filter production, directly affecting the quality and performance of the product, and determining whether the product yield can be guaranteed and mass production can be achieved.Currently commonly used metallization processes include silver spraying, thick film screen printing, etc.

(1) Silver spray
Silver spraying is to spray the ceramic substrate through silver spraying equipment, dry it and then continue spraying. After multiple sprayings, it is sintered.After spraying silver, the surface bonding force of the silver layer is very good, but the silver paste is wasted seriously.Moreover, it requires multiple spraying and drying processes, which results in complex work procedures and high labor costs. This not only increases the company's costs, but also fails to improve mass production efficiency.
(2) Thick film screen printing
Thick film screen printing uses a high-precision thick film screen printing machine to print on the surface of the ceramic substrate, and then sinters it at high temperature to complete the metallization.It has simple operation, high printing efficiency, uniform coating thickness, and can achieve mass production.The process flow is as follows:
1. High-precision thick film screen printing machine
Choose a precision thick film screen printing machine with high printing accuracy, high film thickness consistency, high printing efficiency, high degree of automation, and easy operation to ensure stability and accuracy during the printing process.
2. Prepare ceramic substrate
Make sure the surface of the ceramic substrate is flat and clean.

3. Prepare screen version
Select the appropriate mesh number and film thickness according to product requirements. The particle size of the slurry matches the screen. It has good compatibility and strong adhesion with the ceramic substrate to avoid clogging the screen and causing other quality problems.
4. Prepare slurry
Choose a silver paste with moderate consistency, uniform particles, and stable performance to ensure that problems such as board blocking and string drawing will not occur during the printing process.In addition, physical parameters such as the viscosity of the silver paste need to be adjusted and optimized based on actual production conditions.
5. Silk screen printing
The screen is installed on a high-precision thick film screen printing machine, and then the silver paste is poured onto the screen. Under the action of the scraper, the silver paste is deposited on the ceramic substrate through the holes on the screen to complete printing.
6. Dry
After printing, the ceramic substrate needs to be dried to remove the solvent from the ink.Usually, drying equipment or natural air drying is used, and the drying time is 20-30 minutes.
7. Sintering
The sintering temperature of silver paste is generally between 750℃-850℃, and the sintering time also varies depending on the process.The stability of temperature and time must be maintained during the sintering process to ensure that the silver paste is fully solidified and obtains good conductive properties.
In general, in the metallization process of ceramic dielectric filters, although the silver layer adhesion of the silver spray process is very good, its many processes and the waste of silver paste seriously limit its application in mass production.Relatively speaking, the thick film screen printing process has the advantages of simple operation and uniform coating thickness. It can quickly achieve mass production with a fully automatic production line. The perfect process also provides a reliable method for the metallization of ceramic dielectric filters. solution.In the future, with the continuous advancement of technology and the growing demand, this process is expected to continue to play an important role in the filter industry and help promote the development of mobile communications and other fields.