Microwave Tech - Evaluation and selection of substrate materials for high-speed and high-frequency PCBs

Evaluation and selection of substrate materials for high-speed and high-frequency PCBs

The basic right materials occupy a more and more important position in the development of high-speed and high-frequency PCB technology and products. Low dielectric constant teaching.fl and low dielectric loss are the high-level PCB basic materials. *The important energy item for high frequency is W, the dielectric constant of substrate materials of different resins.

Fi is compared with low dielectric loss due to teaching, and the relationship between them and frequency car 1 temperature*humidity, characteristic impedance control accuracy, etc. is discussed, so that it is difficult to achieve correct and reasonable substrate materials in PCB manufacturing. choose.

Dielectric loss factor of printed circuit board substrate materials

Current + Development and production of high-speed and high-frequency PCBs has become a new trend in the world PCB industry. Substrate material manufacturers develop such substrates, PCB manufacturers research, understand, and select such substrates, and they are becoming the world's substrate material manufacturers. An important issue for PCB manufacturers.

They are all faced with a total of 14 questions: how to make a comprehensive and correct price for the performance of a class of substrate materials used in high-speed and high-frequency PCBs.

1 The base plate occupies the high-speed and high-frequency PCB manufacturing

The development of high-speed and high-frequency PCB products will bring new business opportunities to the PCB industry, from its product design to the selection of substrate materials. Product manufacturing, product inspection, etc. contain new technologies and new levels, and its application fields are also It has been promoted to a new high level: Therefore, the PCB industry with A as the high-speed and high-frequency PCB industry is an industry with added value and a "knowledge economy".

We have noticed that: In the development of the "differentiation strategy", the former U.S. industry puts the development of fast-paced and high-frequency PCB manufacturing technology in a very important position.

The same is true in Taiwan: many large-scale PCB manufacturers in Taiwan have focused on the development of this type of PCB manufacturing technology in the past few years.

In the development of high-speed island frequency PCB industry, the substrate material used is more prominent to the important position^ It is mainly manifested in the following two aspects: Choosing the appropriate substrate material is an important aspect of achieving high-speed and high-frequency PCB.

The high-speed and high-frequency characteristics of PCB are mainly based on two technical approaches: On the one hand, it is to make this kind of PCB become high-density wiring (fine wires and inter-runs, micro-aperture U#-shaped and conductive Reliability of communication and insulation.

In this way, the distance of short message transmission is reduced to reduce the loss in transmission. On the other hand, it is necessary to use high-speed, high-frequency characteristics of PCB substrate materials.

The realization of the latter requires the PCB industry to carry out a more in-depth understanding and research work on this type of substrate material: to find and control the process method for accurate control to achieve the selected substrate material and the manufacturing process and performance of the PCB. And cost requirements can achieve reasonable matching of H.

The substrate material plays an important role in ensuring the performance and reliability of the PCB and improving competitiveness. Sanyu substrate materials have a prominent and important position in the development of high-speed and high-frequency PCB technology products.

Therefore, many %3 manufacturers are developing such PCB products. The focus of their research and experiments is on the selected substrate material.

Many Japanese PCB manufacturers are working to develop the world's high-speed rSf frequency PCB market, to accelerate the application of this high-level substrate material as a "favorable weapon" and achieve; T is very effective, 2 high-speed high-frequency PCB main characteristics and substrate The relationship between the dielectric properties of materials

2,1 The characteristics of high-speed and high-frequency PCB The characteristics of high-speed and high-frequency PCB are mainly manifested in three aspects:

(1) It has the characteristics of transmission loss (small 〇0, short transmission delay time (Tpd), and low distortion of signal transmission;

(2) It has excellent dielectric characteristics. Moreover, the dielectric characteristics (mainly refers to £r, tanS) can still maintain its stability under environmental changes of frequency, humidity, and temperature; U) has a characteristic impedance (A ) High m degree control.

To achieve the above-mentioned characteristics, it is necessary for the substrate material to have a low dielectric constant (er, hereinafter referred to as "dielectric constant" represented by e), low dielectric loss factor (hnS h high-precision characteristic impedance control h_previously also become high-speed An important characteristic requirement of high-frequency PCB, and the thickness of the insulating layer between taiiA and the substrate material, the shape of the conductive circuit pattern (the width of the main guide line) and so on.

Together they constitute the three most important factors for high-precision control of the characteristic ffi resistance value. The performance requirements of the substrate used for high-speed and high-frequency PCB boards. In addition to the following dielectric characteristics, it should also have other main characteristics . Such as excellent heat resistance, processability, formability, and adaptability to the manufacture of high-density roofing boards (such as 30 layers with t) and other characteristics.