A very clear direction of 5G PCB is high-frequency and high-speed materials and boards. Traditional FR4 materials can no longer meet the needs of high-frequency transmission. In terms of material selection, the Dk (dielectric constant) and Df (dissipation factor) of PCB products must be small. 

  Generally, boards with a Dk value of less than 3.5 and a Df of less than 0.01 are selected. At the same time, multi-level HDI products and even products that are interconnected in any order will be promoted. For example, the Apple mobile phone PCB adopts 10-layer arbitrary-level hole interconnection, and the overall stacking scheme of multi-board interconnection in the Z direction. 

  The advantages of space saving and high integration are obvious in the PCB product of this sandwich stacking scheme.

Product advantages：

1. High frequency 

2. high speed, 

3. space saving, 

4. high integration, 

5. small motherboard area, 

6. high precision and strong durability 

7. uniform temperature 

8. efficient heat transfer