High-frequency covering film with high electromagnetic shielding function and preparation method thereof

Abstract

The invention discloses a high-frequency covering film with a high electromagnetic shielding function and a preparation method thereof. The high-frequency covering film sequentially comprises an insulating layer, a bonding layer, a copper foil layer, a first high-frequency bonding layer, a high-frequency insulating layer and a second high-frequency bonding layer from top to bottom, the high-frequency insulating layer is an insulating layer of which the dielectric coefficient is lower than 4.0 and the dielectric loss is lower than 0.015 (@ 10GHz); and the first high-frequency bonding layer andthe second high-frequency bonding layer are both resin adhesive layers with the dielectric coefficient being lower than 4.0, the dielectric loss being 0.002-0.010 (@ 10 GHz) and the water absorption being 0.001-0.5%. According to the invention, the shielding rate can be up to more than 100dB; the dielectric property is good, the dielectric loss is 0.003-0.010 at 10 GHz, and the dielectric coefficient is lower than 4.0; the mechanical property is good, and machining processes such as drilling and hole filling can be coped with; a thick dielectric layer can be designed within a large thickness range, so that signal transmission loss under high frequency is reduced; and soldering tin is good in heat resistance, plate explosion is avoided in the FPC and PCB assembling process, and gas escape is facilitated and plate explosion is avoided through drilling, hole filling and other process designs.

Description

technical field [0001] The invention belongs to the technical field of covering films for printed circuit boards, in particular to a high-frequency covering film with high electromagnetic shielding function, which is suitable for high-frequency and high-speed transmission circuit boards. Background technique [0002] Under the market demand that electronic and communication products tend to be multi-functional and complex, the structure of circuit substrates needs to be lighter, thinner, shorter, and smaller; and in terms of functions, powerful and high-speed signal transmission is required. Therefore, the line density is bound to increase, the distance between the carrier board lines is getting closer and closer, and the operating frequency is moving towards high broadband. In addition, if the line layout and wiring are unreasonable, the electromagnetic interference (Electromagnetic Interference, EMI) will become more serious. It is becoming more and more serious, so it is ...

AI Technical Summary

Problems solved by technology

[0004] The shielding rate of conventional EMI shielding film is generally around 55dB, and it is difficult to reach 70dB

As 5G high-frequency applications even require higher shielding effects, in 5G application scenarios where the shielding rate is required to be greater than 75dB, 80dB or even 100dB, it is difficult to achieve the current EMI shielding film on the market. The thickness of the metal layer and the thickness of the conductive adhesive can meet the performance requirements of high shading rate, but it often encounters the problem of plate explosion in the process

[0005] In addition, the use of EMI shielding film in the processing of FPC board factory has many processes and is quite complicated. It is necessary to paste the cover film on the line and then paste the EMI shielding film on the opening. This is because the conventional cover film only has an insulating effect and does not Does not have the function of electromagnetic shielding after the EMI shielding film is turned on

Images