Product Name: RO4450F Blind Via Four-Layer RF Board
Material Properties: RO4003C, Dielectric Constant 3.38, Dielectric Thickness RO4003C 1.524mm + RO4450F + RO4003C 1.524mm, 

Total Thickness 3.4mm, Surface ENIG 2U, 1-2 Layer Blind Vias, 

Resin Plugged Vias, Dimensions 300x300mm High-Frequency PCB Board, i.e., High-Frequency Circuit Board.
Definition: High-frequency circuit boards refer to special circuit boards specifically designed for use in electromagnetic frequencies that are relatively high. 

They are primarily applied in high-frequency (frequencies exceeding 300MHz, corresponding to wavelengths less than 1 meter) and microwave (frequencies exceeding 3GHz, corresponding to wavelengths less than 0.1 meter) fields. 

These PCB boards are manufactured using standard rigid circuit board production processes or special processing techniques on microwave RF-grade copper-clad laminates. 

Generally, high-frequency boards can be defined as circuit boards with frequencies reaching or exceeding 1GHz.