5G high frequency high speed and microwave board
Summary：A national high-tech enterprise specializing in R&D, production and sales of printed circuit boards. The company has become one of the leading printed circuit board manufacturers in China with its strong manufacturing capacity, modern management system and one-stop, multi-variety business characteristics.
Key words：Circuit boards, high-precision multilayer boards, metal substrates
The design of the high-frequency microwave type multilayer board made of high-frequency base material mixed with FR-4 has a higher density than the low-frequency board. Generally, high-frequency boards are used in circuits with frequencies above 1G. Its dielectric constant is the key, the DK value is very small and stable, the dielectric loss is small, and it has excellent properties such as not easy to absorb water and moisture, heat resistance, and corrosion resistance.
Main process features
① Low loss, high reliability;
② high frequency characteristics;
③ High frequency PCB structure;
Type: Tu M series high frequency sheet
Technical indicators: high frequency sheet, low dielectric constant, low dielectric loss
Finished plate thickness: 1.6+/-0.1mm
Copper foil thickness: 70um
Surface treatment: thick gold process 15u''
Shape accuracy: 0.05mm
The characteristics of microwave printed board manufacturing
The characteristics of microwave printed board manufacturing are mainly reflected in the following aspects:
1. Diversified substrates:
For a long time, the most widely used domestic glass cloth reinforced PTFE copper clad laminate. However, due to its single variety and poor uniformity of dielectric properties, it has become more and more unsuitable for some high-performance requirements. After entering the 1990s, the RT/ Duroid series and TMM series microwave substrate boards produced by Rogers Company in the United States were gradually applied, mainly including glass fiber reinforced PTFE copper clad laminate, ceramic powder filled PTFE copper clad laminate and ceramic powder. Although the thermosetting resin-filled copper clad laminate is expensive, its excellent dielectric properties and mechanical properties still have considerable advantages over domestic microwave printed board substrates. At present, such microwave substrates, especially those with aluminum substrates, are being widely used.
2. The design requires high precision:
The graphic manufacturing accuracy of microwave printed boards will gradually improve, but due to the limitations of the printed board manufacturing process itself, this precision improvement cannot be unlimited, and will enter a stable stage after a certain level. The design content of the microwave board will be greatly enriched. In terms of types, there will be not only single-sided, double-sided, but also microwave multilayer boards. For the grounding of microwave boards, higher requirements will be put forward, such as generally solving the hole metallization of PTFE-based boards and solving the grounding of microwave boards with aluminum substrates. Plating requirements are further diversified, with special emphasis on the protection and plating of aluminum substrates. In addition, higher requirements will be put forward for the overall three-proof protection of microwave boards, especially the three-proof protection of PTFE-based boards.
3. Computer control:
Computer technology is rarely used in the production of traditional microwave printed boards, but with the wide application of CAD technology in design, as well as the high precision and large quantities of microwave printed boards, computer technology is widely used in the manufacture of microwave printed boards. has become an inevitable choice. The design and manufacture of high-precision microwave printed board templates, the numerical control processing of the shape, and the batch production inspection of high-precision microwave printed boards are inseparable from computer technology. Therefore, it is necessary to connect the CAD of the microwave printed board with CAM and CAT, and through the data processing and process intervention of the CAD design, the corresponding numerical control processing files and numerical control inspection files are generated, which are used for the process control, Process inspection and finished product inspection.
4. Specialization in high-precision graphics manufacturing:
Compared with traditional rigid printed boards, the high-precision pattern manufacturing of microwave printed boards is developing in a more specialized direction, including the production and production of high-precision stencil manufacturing, high-precision pattern transfer, high-precision pattern etching and other related processes. Process control technology also includes reasonable manufacturing process routing. According to different design requirements, such as hole metallization, type of surface plating, etc., a reasonable manufacturing process method is formulated. After a large number of process experiments, the process parameters of each related process are optimized, and the process margin of each process is determined.
5. Diversified surface coating:
With the expansion of the application range of microwave printed boards, the environmental conditions of its use are also complicated. At the same time, due to the large number of aluminum substrates used, the surface plating and protection of microwave printed boards are not in the original chemical immersion silver and electroplating. On the basis of tin-cerium alloy, higher requirements are put forward. First, the plating and protection of the surface of the microstrip pattern must meet the welding requirements of microwave devices, and the process technology of electroplating nickel and gold is used to ensure that the microstrip pattern is not damaged in harsh environments. In addition to the solderability coating on the surface of the microstrip pattern, the most important thing is to solve the three-proof protection technology that can effectively protect and not affect the microwave performance. The second is the protection and plating technology of aluminum lining. If the aluminum lining is not protected, it will be corroded quickly when exposed to humidity and salt spray environment. Therefore, with the large-scale application of aluminum lining, its protection technology should be paid enough attention. In addition, it is necessary to study and solve the electroplating technology of aluminum plates. The demand for electroplating silver, tin and other metals on the surface of aluminum lining plates for microwave device welding or other special purposes is gradually increasing. This not only involves the electroplating technology of aluminum plates, but also has microstrip patterns. protection issues.
6. CNC shape processing:
The shape processing of microwave printed boards, especially the three-dimensional shape processing of microwave printed boards with aluminum linings, is a technology that needs to be solved in batch production of microwave printed boards. In the face of thousands of microwave printed boards with aluminum linings, the traditional shape processing method can neither guarantee the manufacturing accuracy and consistency, nor the production cycle, but must adopt advanced computer-controlled numerical control processing technology. . However, the shape processing technology of microwave printed boards with aluminum linings is different from both metal material processing and non-metallic material processing. Due to the coexistence of metal materials and non-metal materials, its processing tools, processing parameters, and processing machines have great particularity, and there are also a large number of technical problems to be solved. The shape processing process is the process with the longest cycle in the manufacturing process of the microwave printed board. Therefore, the quality of the shape processing technology is directly related to the length of the processing cycle of the entire microwave printed board, and affects the development or production cycle of the product.
7. Batch production inspection equipment:
Unlike ordinary single and double-sided boards and multi-layer boards, microwave printed boards not only play the role of structural parts and connectors, but more importantly, they function as signal transmission lines. That is to say, the electrical testing of microwave printed boards for the transmission of high-frequency signals and high-speed digital signals should not only measure whether the "on", "off" and "short-circuit" of the line (or network) meet the requirements, but also should Measure whether the characteristic impedance value is within the specified acceptable range.
In addition, high-precision microwave printed boards have a large amount of data to be tested, such as graphic accuracy, position accuracy, coincidence accuracy, coating thickness, and three-dimensional dimensional accuracy. At present, the domestic microwave printed board batch production inspection technology is very backward. The current method is basically based on manual visual inspection, supplemented by some simple measurement tools. This primitive and simple inspection method is difficult to deal with the batch production requirements of microwave printed boards with hundreds or thousands of data, not only the inspection cycle is long, but also there are many errors and omissions, thus forcing the manufacturing of microwave printed boards toward batch production inspection equipment direction of development.