Double-layer electromagnetic shielding film and preparation method thereof

Abstract

The invention discloses double-layer electromagnetic shielding film. The shielding film comprises carrier film, a first insulating coating layer coated on the barrier film, a second insulating coatinglayer coated on the first insulating coating layer, a metal layer compounded on the metal layer, an electromagnetic wave shielding coating layer coated on the metal layer and release type protectivefilm arranged on the electromagnetic wave shielding coating layer; the carrier film is matt release film; coating of the first insulating coating layer is wear-resisting acrylate coating or polyurethane coating, the abrasive resistance performance is greater than 1000 times, and the thickness is 1-2 microns; coating of the second insulating coating layer is high-filling high-toughness acrylate coating or polyurethane coating or rubber coating, the number of bending resistance times is greater than 80000, and the thickness is 2-7 microns; the metal layer is thin film prepared from rolled metalfoils, and the thickness of the metal layer is 3-9 microns. The film has better toughness, bending resistance performance and product smoothness and a better shielding effect.

Description

technical field [0001] The invention relates to the technical field of electromagnetic shielding, in particular to a double-layer electromagnetic shielding film and a preparation method thereof. Background technique [0002] In the flexible printed circuit board (FPC) industry, with the upgrading of electronic devices such as smart phones and Ipads, the requirements for electromagnetic shielding are also getting higher and higher. Due to the processing technology and use requirements of FPC, the electromagnetic shielding film used on FPC must meet the following requirements: high temperature resistance (180°C, several hours, 270°C, short time), high pressure (12MPa), flexibility and bending resistance, 1000h constant temperature Constant humidity (85℃ temperature, 85% humidity), chemical resistance (acid, alkali, organic solvent), ultrasonic cleaning resistance. [0003] In the prior art, the electromagnetic shielding film has the following problems: (1) the insulating laye...

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Problems solved by technology

[0003] In the prior art, the electromagnetic shielding film has the following problems: (1) the insulating layer of the electromagnetic shielding film adopts ink, because the ink molecular weight is low, the filler ratio is high, and the crosslinking density is large, the ink is printed on the common carrier film, and the volume of the curing reaction Large shrinkage, due to the brittle and hard characteristics of the ink itself, will cause the electromagnetic shielding film produced with ink to be hard and brittle, and not resistant to bending; used in the FPC industry, resulting in the flexibility and bending resistance of the electromagnetic shielding film Poor stability and product flatness; when the carrier film is torn off, the ink is easy to adhere to the carrier film; the ink itself is relatively brittle and prone to micro-cracks, resulting in the infiltration of the liquid medicine during the subsequent processing of the FPC, resulting in the product being scrapped

(2) The shielding layer of the electromagnetic shielding film adopts a metal shielding layer to improve the shielding effect. Usually, the method of vacuum sputtering or electroplating is used to form a metal layer on the insulating layer. The thickness of the metal layer formed by this method is limited and the efficiency is low. And The electroplated metal layer is easy to produce columnar crystals, which makes the metal layer not ductile. In the subsequent complex high-temperature and high-pressure operation process of FPC, it is prone to cracks, oxidation, etc., which will reduce the shielding performance or even lose the shielding performance. At the same time In the subsequent reflow soldering process, it is easy to foam and delaminate, which cannot meet the requirements of FPC for flexibility, high temperature and high pressure resistance, and liquid impact resistance.

(3) The shielding performance of the shielding film made of ordinary conductive adhesive is difficult to reach 60dB. With the development of information technology and the commercial application of 5G communication, the shielding performance of FPC is often required to be greater than 60dB, or even 80dB. The ordinary shielding film has been completely Impossible to meet the requirements of the FPC industry for high shielding performance

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