CN101521985A - Shielding structure and flexible printed circuit board with same - Google Patents

Abstract

A shielding structure and flexible printed circuit board with the shielding structure comprise a flexible printed circuit board and a shielding structure arranged on the flexible printed circuit board, wherein the shielding structure comprises a metal layer and a polyimide layer, the thickness of the metal layer is 1-20 μm, and the thickness of the polyimide layer is 1-15 μm. The shielding structure has excellent flexibility and flexibility, and is particularly suitable for electronic products such as flip phones, slide phones and the like.

Description

Shielding structure and flexible printed circuit board with the shielding structure

field of invention

The present invention relates to a shielding structure, and more particularly, to a shielding structure for a flexible printed circuit board.

Background technique

As electronic products are becoming thinner, smaller, more functional, and faster, most of their wiring materials are flexible printed circuit boards (FPC) with high design freedom and good bendability. However, different electronic products will generate different electromagnetic waves, which will easily cause electromagnetic interference (EMI) and cause damage to electronic products, and even endanger human health. In this case, the film-type flexible printed circuit board with shielding film is applied to mobile phones , digital cameras, digital video cameras and other electronic products have been widely used.

In the known technology, plastic materials are used as shielding films for electromagnetic interference, and the manufacturing method can be to dope conductive fibers or particles in plastic materials to form conductive plastic materials, or by foil pasting method, ion beam Plating conductive metals on the surface of plastic materials, such as vacuum evaporation, electroplating, etc., to reduce electromagnetic interference through the shielding efficiency of conductive metals to electromagnetic waves.

Although the shielding layer of electronic products is formed by adding conductive metal to plastic materials or plating conductive metal on its surface, it has the advantages of simple processing, light weight, beautiful appearance, etc. However, due to the expansion coefficient of plastic materials and conductive metals, Different characteristics such as glass transition temperature (Tg) may easily cause problems such as poor bonding, reduced electrical conductivity, and poor flexibility.

Therefore, how to propose a shielding material that can overcome various defects of the prior art has become a difficult problem to be overcome urgently.

Contents of the invention

In view of the various shortcomings of the above-mentioned known technologies, the main purpose of the present invention is to provide a shielding structure with high flexibility and good flexibility.

Another object of the present invention is to provide a flexible printed circuit board with high flexibility and a good flexible shielding structure.

In order to achieve the above and other objects, the present invention discloses a shielding structure, comprising a metal layer and a polyimide layer formed on the metal layer, and the thickness of the metal layer is between 1-20 μm, the polyimide The thickness of the layer is between 1-15 μm. The above-mentioned shielding structure has excellent softness and good flexibility, and is especially suitable for electronic products such as clamshell and slide mobile phones.

The present invention also discloses a flexible printed circuit board with the above-mentioned shielding structure, including a flexible printed circuit board and a shielding structure arranged on the flexible printed circuit board, wherein the above-mentioned shielding structure includes a metal layer and a polyimide layer, and the The thickness of the metal layer is between 1-20 μm, and the thickness of the polyimide layer is between 1-15 μm.

Description of drawings

Fig. 1 is the schematic diagram of shielding structure of the present invention; And

FIG. 2 is a schematic diagram of a flexible printed circuit board with a shielding structure according to the present invention.

110, 210 shielding structure

112, 212 metal layer

114, 214 polyimide layer

200 flexible printed circuit boards

220 conductive adhesive

Detailed ways

The implementation of the present invention will be described below through specific specific examples.

Fig. 1 shows a specific embodiment of the shielding structure of the present invention. The shielding structure 110 includes a metal layer 112 and a polyimide layer 114 formed on the metal layer. In the above specific embodiments, copper is used as the metal layer, and examples of the copper metal include electrolytic copper, rolled copper, and the like. In the shielding structure of the present invention, the thickness of the above-mentioned metal layer is usually in the range of 1-20 μm, preferably in the range of 1-6 μm; the thickness of the above-mentioned polyimide layer is usually between 1-15 μm, preferably 3- in the range of 10 μm.

The above-mentioned shielding structure 110 may be formed by a coating method. For example, using copper foil as the base material, polyamic acid is coated on the copper foil, dried in an oven and imidized (Imidization) to form a single-sided adhesive-free double-layer copper-clad foil film .

FIG. 2 shows a specific embodiment of a flexible printed circuit board with a shielding structure according to the present invention, including a flexible printed circuit board 200 ; and a shielding structure 210 disposed on the flexible printed circuit board. The shielding structure 210 includes a metal layer 212 and a polyimide layer 214 , and is disposed on the above-mentioned flexible printed circuit board through a conductive glue 220 . Usually, the thickness of the metal layer in the above-mentioned shielding structure is in the range of 1-20 μm, preferably in the range of 1-6 μm; the thickness of the above-mentioned polyimide layer is usually between 1-15 μm, preferably in the range of 3-10 μm Inside.

Example

The carrier plates used in the Examples and Comparative Examples are detailed as follows:

Examples 1 to 6:

The polyimide precursor (Precursor) - polyamic acid (PAA), or polyimide coating (Polyimide Varnish) is evenly coated on the copper foil by the coating method to form a semi-finished shielding structure layer. Put the above-mentioned semi-finished shielding structure layer into a closed nitrogen oven, the oxygen content of the nitrogen oven needs to be controlled at less than 0.5%, and optimally, it can be kept below 0.2% or lower, and its heating temperature is 50°C to 350°C degree (℃), baking time is 15 to 240 minutes. Then, perform dehydration drying and imidization (Imidization), or directly dry to make a double-layer copper-clad foil film. Copper clad foil films of different thicknesses are completed through the above process, so that the anisotropic conductive film (ACF) can be directly used on the flexible printed circuit board with the layout of the circuit part to form a carrier with different thickness and shielding structure. plate, and the results are shown in Table 1.

Comparative example 1:

The plastic material is used as the shielding structure layer, and it is glued on the printed circuit board through an anisotropic conductive adhesive film.

Table 1

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Comparative example 1 Polyimide layer (μm) 13 13 13 8 5 5 Plastic layer (μm) 5 Metal layer (μm) 18 12 9 5 3 1 0.1 Conductive plastic 17 17 17 17 17 17 17

(μm) Circuit board (μm) 34.2 34.2 34.2 34.2 34.2 34.2 34.2 Total thickness (μm) 82.2 73.2 73.2 74.2 59.2 57.2 56.3

The circuit board samples made above with different thicknesses were cut into test pieces of appropriate size, and softness, sliding table test and bending test were carried out, and the resistance value change rate was calculated after the sliding table test and bending test. The softness (gf) of the sample is tested by the reaction force softness tester. The test conditions are AC220V, the measurement range is 410 grams, the readability is 0.001 grams, and the test R angle is 2.35 millimeters (mm); through the sliding table test Calculate the resistance value change rate of the test piece by the bending machine. The test conditions are AC220V, 3.0mm spacing, 1.5mm at the R angle and speed = 400 (rotational speed) rpm; the resistance value change rate is calculated by testing the sample piece by the bending test machine. The test conditions are AC220V voltage, bending angle of 0 to 160 degrees, bending speed of 40 times/min and bending R angle of 1.5 mm (radius). The results are shown in Table 2.

Table 2

From the test results in Table 2, it can be seen that the flexible printed circuit board with shielding structure of the present invention has high flexibility and flexibility, and the resistance value change rate of the slide table test is lower than the standard of 3.1%. In the bending test, the resistance value change rate of the bending test can be lower than 2.9%, that is, the resistance value change rate of the bending test can be lower than the standard value of 15%.

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Any person skilled in the art can modify and change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be as listed in the preceding claims.

Claims (10)

1. A flexible printed circuit board with a shielding structure, comprising: flexible printed circuit boards; and The shielding structure arranged on the flexible printed circuit board is characterized in that the shielding structure includes a metal layer and a polyimide layer, and the thickness of the metal layer is between 1-20 μm, and the polyimide layer The thickness of the amine layer is between 1-15 μm. 2. The flexible printed circuit board according to claim 1, wherein the thickness of the metal layer is between 1-6 μm. 3. The flexible printed circuit board according to claim 1, wherein the thickness of the polyimide layer is between 3-10 μm. 4. The flexible printed circuit board according to claim 1, wherein the metal is copper. 5. The flexible printed circuit board according to claim 1, wherein the metal is rolled copper or electrolytic copper. 6. A shielding structure, comprising: metal layer; and a polyimide layer formed on the metal layer; It is characterized in that the thickness of the metal layer is between 1-20 μm, and the thickness of the polyimide layer is between 1-15 μm. 7. The shielding structure according to claim 6, wherein the thickness of the metal layer is between 1-6 μm. 8. The shielding structure according to claim 6, wherein the thickness of the polyimide layer is between 3-10 μm. 9. The shielding structure of claim 6, wherein the metal is copper. 10. The shielding structure according to claim 6, wherein the metal is rolled copper or electrolytic copper.

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