Reflective electromagnetic shielding film for FPC and preparation method thereof

Abstract

The invention provides a preparation method of a reflective electromagnetic shielding film for FPC, comprising the following steps: first, preparing a coating of a first insulating coating layer, a second insulating coating layer and an electromagnetic wave reflecting coating; 2, coat; The first insulating coating layer is an abrasion-resistant coating, and the abrasion resistance is more than 1000 times; The second insulating coating layer is a coating with high filling and high toughness, and the bending resistance is more than 80000; The coating of electromagnetic wave reflective coating comprises a base resin and a metal filler, wherein the metal filler is sheet silver-coated glass or sheet silver-coated copper powder or leaf silver-coated copper powder or dendritic silver-coated copper powder; The carrier membrane is matte photoionization membrane. The metal filler has a size of 1 to 2 [mi]m in the thickness direction, a planar size of 3 to 9 [mu]m, and 3 to 5 bifurcations on theleaf-shaped metal filler; the ratio of the matrix resin to the metal filler of the electromagnetic wave reflective coating is 1:1.5 to 1 :5 The invention has better flexibility, bending resistance, product flatness and shielding effect.

Description

technical field [0001] The invention relates to the technical field of electromagnetic shielding, in particular to a reflective electromagnetic shielding film for FPC 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 insulatin...

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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 or a conductive layer. In the subsequent complex high-temperature and high-pressure operation process of FPC, the metal layer is prone to cracks, oxidation, etc., which will reduce the shielding performance. , and even lose the shielding performance, and at the same time, it is easy to bubble and delaminate in the subsequent reflow soldering process

(3) The shielding film made of ordinary conductive adhesive is difficult to meet the needs of the FPC industry because of its low conductivity, poor continuous conduction, and poor shielding performance.

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