With the continuous development of high-frequency electronic equipment, especially in the increasing development of wireless networks and satellite communications, information products are moving towards high-speed and high-frequency, and communication products are moving towards the standardization of voice, video and data for wireless transmission with large capacity and high speed. Therefore, the new generation of products developed require high-frequency substrates, and the process technology of high-frequency PCB board production is constantly improving to meet the needs of different users. The editor has been engaged in PCB production for more than 10 years, and summarizes the matters encountered in the production process, and briefly describes the matters that should be paid attention to in the production of high-frequency microwave PCB boards.

1. Basic requirements of high frequency microwave board

1. Substrate materials of microwave printed boards When designing simulations, electronic engineers must select substrate materials with small dielectric constant and dielectric loss tangent according to the needs of actual signal transmission. Therefore, when accepting customer orders, it is necessary to carefully check the parameters of the sheet and must meet the design requirements.

2. The production accuracy of the RF line requires the transmission of high-frequency signals, and the characteristic impedance requirements of the printed RF line are very strict, that is, the tolerance requirement for the RF line is generally ±20um, and the rough edge of the RF line should be very neat, tiny burrs, No gaps are allowed.

3. Coating requirements The characteristic impedance of the high-frequency microwave board transmission line directly affects the transmission quality of the microwave signal. The characteristic impedance value has a certain relationship with the copper thickness of the finished PCB board. Especially for the microwave board with metallized holes, the thickness of the finished copper affects the tolerance of the wires after etching. Therefore, the size and uniformity of copper thickness of pattern plating should be strictly controlled.

4. Requirements for external machining The microwave printed board substrate material is very different from the conventional FR4 epoxy glass cloth material in terms of machining; secondly, the processing accuracy of the microwave printed board substrate material is much stricter than that of FR4. , the general shape tolerance is ±0.1mm (the high precision is generally ±0.05mm or 0~-0.1mm).

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2. Matters needing attention in the production of high-frequency microwave boards

1. Processing of engineering CAM data: When CAM processing the customer's files, we must follow the customer's design, pay attention to the production tolerance requirements of the transmission line, and make appropriate process compensation according to the tolerance requirements and the factory's process capabilities.

2. Cutting: Usually, automatic cutting machines are used for cutting FR4 plates, but for microwave dielectric materials, the utilization rate of the plates needs to be considered, and different cutting methods should be selected according to the different medium characteristics of the plates, mostly milling , cutting mainly, so as not to affect the flatness of the material and the quality of the board.

3. Drilling: For different high-frequency dielectric materials, adjust the drilling parameters, and have special requirements for the top angle, blade length, helix angle, etc. of the drill bit, try to use a new knife to avoid burrs.