High Frequency Microwave RF Board

With the high frequency PCB technology and products occupy an increasingly important position, the development of high frequency PCB board also appeared high-speed, which is more important aspect is the choice of low dielectric constant and low dielectric loss factor of the material, which is PCB high frequency board to achieve high-speed, high frequency important performance items. Article for the substrate material dielectric constant and dielectric loss relationship to discuss, and their relationship with the external environment to make the corresponding description, so that in the manufacture of PCB for a variety of substrate materials for reasonable and correct evaluation and use.

At present, there are three main types of commercialized high frequency boards: polytetrafluoroethylene (PTFE) boards; thermosetting PPO (Polyphenyl Oxide); crosslinked polybutadiene substrate and epoxy composite substrate (FR-4). PTFE substrate has the advantages of low dielectric loss, small dielectric constant and small change with temperature and frequency, and close to the coefficient of thermal expansion of the metal copper foil, etc., and the coefficient of thermal expansion is close to the metal copper foil, etc., so that it is suitable for PCB manufacturing.

The PTFE substrates prepared with glass fiber and ceramics, e.g., RO3200, RO3210, RO4003, etc., have been able to meet the requirements of dielectric constants from 2.2 to 10.8, and operating frequency bands from 30 MHz to 30 GHz.

Although, PTFE microwave board manufacturing development is rapid, but with the corresponding process is improved by the traditional FR-4 printed circuit manufacturing process. Now the high-speed development of electronic information products, especially microwave devices, integration and greatly improved digitalization, high-frequency, multifunctionality and application in special environments and other requirements have been to the general PTFE high frequency boards as well as the manufacturing process has posed a challenge. For the microwave PCB of high-speed, high frequency characteristics, mainly through two aspects of the technology path: on the one hand, the development of such a high-density wiring micro-fine wires and spacing, tiny aperture, thin shape, as well as conduction, insulation and high reliability. In this way, the signal transmission distance can be further shortened to reduce its loss in transmission.

On the other hand, the use of high-speed, high frequency characteristics of the substrate material. The realization of the latter, the industry is required to carry out a more in-depth understanding of such substrate materials, research work to find out and master the accurate control of the process, in order to achieve the chosen substrate materials and manufacturing process, performance and cost requirements can be achieved to reasonably match the purpose.