KR100636826B1 - Noise-suppression flexible films, electromagnetic shielded circuit boards and including the same - Google Patents

Abstract

Provided are a noise reducing soft film which is used to reduce effectively the noise in a range of radio frequency, and a circuit board and a polymer film containing the noise reducing soft film at the surface or the inside. The noise reducing soft film(4) comprises a multilayered hybrid thin film which comprises a Co-Fe-based or Co-Fe/Ni-Fe-based magnetic layer(2) and a polyimide layer. Preferably the multilayered hybrid thin film comprises a polyimide layer; a magnetic layer(2); and a polymer layer(5). The molar ratio of Co/Fe in the Co-Fe-based magnetic layer is 10-90 %; the molar ratio of Ni-Fe-based magnetic layer is 10-90 %; and the polyimide layer is formed by the thermal reaction or photoreaction of a coated poly(amic acid) layer.

Description

Noise reduction flexible film and electromagnetic shielding circuit board including same {NOISE-SUPPRESSION FLEXIBLE FILMS, ELECTROMAGNETIC SHIELDED CIRCUIT BOARDS AND INCLUDING THE SAME}

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view of a circuit board or film in which a multilayer thin film noise attenuation layer composed of a granular magnetic layer / polyimide layer is formed on a silicon circuit board or a polyimide circuit board or a polymer film.

FIG. 2 is a schematic cross-sectional view of a circuit board or film in which a multilayer thin film noise attenuation layer composed of a polyimide / granula magnetic layer is formed on a silicon circuit board or a polyimide circuit board or a polymer film. FIG.

3 is a schematic cross-sectional view of a circuit board or film in which a multilayer thin film noise attenuation layer composed of a polyimide / granular magnetic layer / polyimide layer is formed on a silicon circuit board or a polyimide circuit board or a polymer film.

4 is a schematic cross-sectional view of a multilayer flexible circuit board or film incorporating a noise attenuation layer composed of a granular magnetic layer, a transmission line, and a polyimide layer on a silicon substrate or a polyimide film.

5 is a schematic cross-sectional view of an embedded multilayer flexible circuit board or film composed of a polyimide layer, a granular magnetic layer, a transmission line, and a polyimide layer on a silicon substrate or polyimide film.

6 is a schematic cross-sectional view of a multilayer flexible circuit board or film embedded with a noise attenuation layer composed of a granular magnetic layer, a polyimide layer, a transmission line, a granular magnetic layer, and a polyimide layer on a silicon wafer or polyimide film.

FIG. 7 is a graph showing a loss power / input power ratio of a multilayer thin film noise attenuator composed of a polyimide / Co—Fe magnetic layer / polyimide layer.

8 is a graph showing a loss power / input power ratio of a multilayer thin film noise attenuator composed of polyimide / (Co-Fe / Ni-Fe magnetic layer) / polyimide layer.

*** Explanation of symbols for main parts of drawing ***

1: silicon circuit board 2: magnetic layer

3: polymer layer 4: flexible circuit board

5: transmission line 6: transmission line

The present invention not only shields electromagnetic waves emitted from an external electronic device or prevents the electromagnetic waves generated from the inside of the electronic device from being discharged to the outside, as well as interference between transmission circuits inside the device or malfunctions caused by external radio waves. The present invention relates to a silicon circuit board, a flexible circuit board and a film for noise countermeasure, and a method for manufacturing the same, which are designed to reduce the effects of the noise.

According to the present invention, a noise attenuating circuit board or a film is formed on or inside a silicon circuit board. In addition, the noise reduction layer of the granular magnetic layer / dielectric polymer layer is embedded in the flexible polymer film or the flexible circuit board, or characterized in that the noise reduction layer is formed on the top.

In recent years, digital electronic devices have increased the demand for high speed, high frequency, high functionality, miniaturization, and ultra-thin product type of circuit signal processing speed of electronic devices. In particular, flexible electronic devices have high demands for flexibility. It is increasing. In order to meet these demands, there is a tendency to mix active elements and passive elements that emit dielectric noise as circuits become denser with semiconductor elements or the like. As a result, capacitive coupling, increase of line coupling by inductive coupling, interference by radiation noise, etc. occur, and the equipment often does not operate normally and malfunctions. In some cases, these noises may affect external devices.

In electronic devices of high speed, high performance, and high density, noise countermeasures, electromagnetic interference countermeasures, and particularly, low frequency filters in the 100 MHz to 20 GHz band include a low pass filter and a shielding method. The countermeasures against noise by components require not only the mounting space but also considerations from the design stage for miniaturization and thinning, so it is not suitable as an urgent countermeasure against the short product life. Inductance components are still inadequate for use in the radio-frequency (RF) band due to the low frequency characteristics of real permeability.

With the trend toward miniaturization of digital electronic devices, ultra-thinning for noise countermeasure films used in the above-described RF band is required and further increased. Sheet-shaped electromagnetic shielding materials using conventional ferrite, copper, permalloy, and sandast alloys use the noise reduction effect due to magnetic loss, and are sheets or fabrics of thickness of 100 microns or more, mainly 1 mm or more, and high frequency. In addition, the permeability is insufficient to limit the thinning, and the spectral permeability of the imaginary part is also low, resulting in low noise reduction effect. Therefore, although components such as coils and filters can be used in the frequency bands lower than several 10 to several 100 MHz and higher frequency bands, there are no noise countermeasure parts that are convenient to use in the aforementioned RF band. Even if there are passive components corresponding to this, enormous cost is required to change the design of the substrate or the like.

In order to solve such a problem, the invention of the noise countermeasure circuit board or film that can be applied to a wider frequency than the magnetic sheet and has a noise reduction effect even in a thin film form is required. Especially in flexible display, electronic devices or flexible printed circuits (FPC), the noise reduction method by a large amount of passive components is difficult to mount the passive components and due to the size limitation of the passive components, Not only that, but also low stability against repeated bending. Therefore, there is an urgent need for the development of an embedded noise attenuator which is advantageous for stability against bending and thinning.

Accordingly, an object of the present invention is to provide a thin noise attenuator that can be used in the RF band and a noise attenuating circuit board or film including the same.

In addition, the present invention provides a flexible noise reduction flexible substrate or film that is stable against repetitive warpage.

In order to achieve the above object, the present invention provides a noise reduction sheet made of a multilayer hybrid film including a magnetic layer and a polyimide layer.

The multilayer hybrid film may be composed of a polyimide layer, a magnetic layer, and a polymer layer, and a composite layer including a Co-Fe-based or Co-Fe magnetic layer and a Ni-Fe magnetic layer may be used as the magnetic layer. The Co / Fe molar ratio or Ni / Fe molar ratio of the magnetic layer is preferably in the range of 10-90%.

In addition, the microstructure of the magnetic layer may be a nano granular layer, because the thickness of the magnetic layer is nanometer level, and the polymer material used to form the polyimide and the metal thin film layer of the magnetic layer react with each other. This is because the nucleus layer (particle layer) is formed. Since the initial magnetic layer is on the order of nanometers, for example about 10 nm, the resulting granular layer is also about 10 nm thick. When the granular layer is formed, the electrical resistance is increased, thereby improving the reflection loss characteristic.

The noise reduction sheet is a thin laminate formed on or embedded in a surface of a rigid circuit board, a flexible circuit board, and other polymer films such as silicon, and is effective in reducing noise and exhibiting flexibility.

More specifically, the noise attenuating circuit board or film according to the present invention is mounted inside an electronic device such as a mobile phone, a wireless telephone, a digital camera, an office automation device, and prevents an interference caused by electromagnetic noise, an unwanted signal interference due to crosstalk, and a malfunction. can do.

Various structures of the circuit board to the film to which the noise reduction sheet according to the present invention is applied are exemplarily illustrated in FIGS. 1 to 6.

1 shows a nano granular magnetic layer 2 formed on a silicon wafer or a silicon circuit board 1 or on a flexible circuit board 4 on which a polymer matrix film or a circuit is formed, and an insulating polymer layer 3 thereon. A circuit board or film having a noise attenuation layer made of an organic and inorganic hybrid thin film having a multi-layer structure formed thereon is shown.

2 shows a multilayer structure in which an insulating polymer layer 3 and a nano granular magnetic layer 2 are sequentially formed on a silicon wafer or a silicon circuit board 1 or on a flexible circuit board 4 on which a polymer matrix film or a circuit is formed. A circuit board or film having an organic, inorganic hybrid thin film noise reduction layer is shown.

1 and 2, reference numeral 6 denotes a transmission line such as a metal wire.

3 shows an insulating polymer layer 3, a nano granular magnetic layer 2, and an insulating polymer layer 3 formed on a silicon wafer or a silicon circuit board 1 or on a polymer matrix film or a flexible circuit board 4. A circuit board or film having an organic, inorganic hybrid thin film noise reduction layer having a multilayer structure is shown.

4 is a multilayer thin film noise having a structure in which a magnetic layer is embedded by stacking a granular magnetic layer 2, a transmission line 5, and a polyimide layer 3 on a silicon wafer 1 or a polyimide film 4. A circuit board to a film having a damping layer is shown.

FIG. 5 illustrates a multilayer thin film noise attenuation layer composed of a polyimide layer 3, a granular magnetic layer 2, a transmission line 5, and a polyimide layer 3 on a silicon wafer 1 or a polyimide film 4. It shows a circuit board or a film having.

6 shows a granular magnetic layer 2, a polyimide layer 3, a transmission line 5, a granular magnetic layer 2, and a polyimide layer 3 on a silicon wafer 1 or a polyimide film 4. A circuit board to a film having a multilayer thin film noise reduction layer constructed is shown.

As described above, the noise attenuating circuit board or the film according to the present invention can not only make the thickness thinner by arranging the organic and inorganic hybrid thin film noise attenuation layer on the circuit where the noise is radiated or under the wiring or the upper wiring, but also the flexible circuit. When applied to a substrate, the adhesion to the polyimide polymer matrix is excellent, and the bending property is improved.

An example of the manufacturing method of the thin film noise reduction circuit board to the film according to the present invention will be described.

RF band noise attenuation circuit board or film according to the present invention to form a magnetic thin film on a silicon circuit board or a flexible circuit board using a DC macronetron type spatter device, and to form a polymer dielectric layer such as polyimide thereon Are manufactured.

As a device for manufacturing a magnetic thin film, a high vacuum spattering device equipped with a magnetic alloy target and an ion milling device in a main chamber was used. As a thin film manufacturing condition, 99.999% Ar gas is used as the spattering gas, and the vacuum in the chamber is reduced to 1.0 × 10 ^-8 torr or less in the main chamber to minimize the influence of residual gas. load-lock chamber) was maintained at 5 × 10 ⁻⁷ torr or less. Co-Fe alloy was used as the magnetic layer, and the formation of the magnetic thin film was controlled by the deposition conditions such as gas flow rate, deposition pressure, and deposition power so that the deposition rate was 1.5 to 2.5 Å / sec. And a specimen holder capable of generating a uniform magnetic field of 100 ± 5 Oe in the specimen to induce the exchange bias fixation direction. Ni-Fe magnetic thin film used as another magnetic layer was prepared by adjusting the deposition conditions such as gas flow rate, deposition pressure and deposition power so that the deposition rate is 1 ~ 2 Å / sec. Co-Fe or Co-Fe / Ni-Fe magnetic thin films were formed on the silicon wafer, and the polyamic acid solution was coated on the silicon wafer at 2500 rpm for 30 seconds using a spin coater, followed by drying. The dried samples were heat-treated in an oxidizing atmosphere, a hydrogen atmosphere, and a vacuum atmosphere from 100 degrees Celsius to 450 degrees to obtain a granular magnetic thin film.

The polymer matrix of the present invention is a polyimide film having excellent insulation properties and is coated with a polyamic acid solution reacted using N-methyl pyrrolidine (NMP) as a pyromellitic dianhydride (PMDA) and an oxydianiline (ODA) solvent to heat at 250 to 450 degrees Celsius. Curing to prepare a polyimide film. In applications requiring a reaction at a low temperature, a polyimide film may be prepared using a photosensitive polyamic acid solution reacted by adding a photosensitive monomer. The thickness of the polyimide film was adjusted from 1 nm to 1000 nm by controlling the concentration of polyamic acid, and could be changed to more than that as needed.

The magnetic layer was able to change the Co-Fe or Ni-Fe composition ratio from 10-90, and the thickness of one layer could be adjusted from 1 nm to 200 nm or more. There is a difference in the shape and size of the granules made according to the thickness of the magnetic layer, and thus it is possible to produce magnetic films of various characteristics.

The thin film manufactured by the above method forms a noise reduction layer of 20 × 10 mm on a microstrip line formed on a dielectric substrate using a network analyzer (HP 8720) to transmit between transmission lines. The coefficient S ₂₁ and the reflection coefficient S ₁₁ were measured. The reduction effect of electromagnetic wave was evaluated by the loss power and input power ratio (P _loss / P _in )

Loss of the microstrip line itself / input power ratio difference in the absence of loss / input power ratio and the noise reduction of the noise attenuation layer layer, _loss △ P / P _in is calculated as follows.

△ P _loss / P _in = [ P _loss / P _in ] _{Magnetic layer-} [ P _loss / P _in ] _{Without magnetic layer}

The following examples will describe specific examples of the present invention, but the present invention is not limited to the following examples.

Example 1

Co-Fe magnetic thin films are formed on the silicon circuit board, the flexible circuit board, and the flexible film using a DC magnetron-type spatter device to a thickness of 100 Å and spin-coated polyamide acid diluted with N-methyl pyrrolidine is formed thereon. After drying, the resultant was heat-treated at 300 ° C. for 1 hour in air to obtain a noise attenuating circuit board or film having a granular magnetic layer and a polyimide layer.

Example 2

In the same manner as in Example 1, a Co-Fe magnetic thin film was formed to a thickness of 100 mm, spin-coated polyamide acid diluted in N-methyl pyrrolidine, dried and heat-treated at 400 degrees Celsius for 1 hour in air. A noise attenuating circuit board or a film having a cannula magnetic layer and a polyimide layer was obtained.

Example 3

In the same manner as in Example 1, a Co-Fe magnetic thin film was formed to a thickness of 100 mm, spin-coated polyamide acid diluted in N-methyl pyrrolidine, dried and heat-treated in vacuum at 300 ° C. for 1 hour. A noise attenuating circuit board or a film having a cannula magnetic layer and a polyimide layer was obtained.

Example 4

In the same manner as in Example 1, a Co-Fe magnetic thin film was formed to a thickness of 100 mm, spin-coated polyamide acid diluted in N-methyl pyrrolidine, dried and heat-treated in vacuum at 400 ° C. for 1 hour. A noise attenuating circuit board or a film having a cannula magnetic layer and a polyimide layer was obtained.

Example 5

Polyamide acid diluted in N-methyl pyrrolidine was spin-coated on a silicon circuit board, a flexible flexible circuit board, and a flexible film, dried, and thermally cured at 300 degrees Celsius for 1 hour to form a polyimide thin film. Co-Fe and Ni-Fe magnetic thin films were formed to each 50 Å thickness by using a DC magnetron-type spatter apparatus, spin-coated polyamide acid diluted in N-methyl pyrrolidine, dried and air-dried thereon. Heat treatment was performed at 300 degrees Celsius for 1 hour to obtain a noise attenuating circuit board or film having a granular magnetic layer and a polyimide layer.

Example 6

In the same manner as in Example 5, Co-Fe and Ni-Fe magnetic thin films were formed to a thickness of 50 각각, respectively, and spin-coated polyamic acid diluted in N-methyl pyrrolidine thereon, dried, and then dried in air at 400 degrees Celsius. Heat treatment was performed for a period of time to obtain a noise attenuating circuit board or film having a granular magnetic layer and a polyimide layer.

Example 7

In the same manner as in Example 5, Co-Fe and Ni-Fe magnetic thin films were formed to have a thickness of 50 각각, respectively, and spin-coated polyamide acid diluted in N-methyl pyrrolidine thereon, dried, and dried at 1,300 degrees Celsius in vacuum. Heat treatment was performed for a period of time to obtain a noise attenuating circuit board or film having a granular magnetic layer and a polyimide layer.

Example 8

In the same manner as in Example 5, Co-Fe and Ni-Fe magnetic thin films were formed to a thickness of 50 Å, respectively, and spin-coated polyamide acid diluted in N-methyl pyrrolidine thereon, dried, and dried at 400 degrees Celsius in vacuum. Heat treatment was performed for a period of time to obtain a noise attenuating circuit board or film having a granular magnetic layer and a polyimide layer.

FIG. 7 is a graph showing a loss power / input power ratio of a multilayer thin film noise attenuator composed of a Co-Fe magnetic layer and a polyimide layer according to Examples 1 to 4, and FIG. 8 shows Co-Fe / according to Examples 5 to 8. It is a graph showing the loss power / input power ratio of a multilayer thin film noise attenuator composed of a Ni-Fe magnetic layer and a polyimide layer. The heat dissipation in air showed higher power loss in the frequency band of 45 GHz to 3 GHz than in heat treatment in air, whereas the specimens heat-treated in air showed higher characteristics at frequencies above 3 GHz. By heat treatment in air and at high temperature, the frequency characteristics tended to be high frequency. The thin film noise attenuator of the present invention exhibited an attenuation effect despite the extremely thin magnetic layer thickness of 10 nm than the conventional sheet.

As described above, the noise attenuating circuit board or the film according to the present invention has a polyimide layer and a nano granular magnetic layer mixed inside or on a printed circuit board, a silicon integrated circuit board, a polymer film, or a flexible board to which noise is radiated. By inserting the organic or inorganic composite noise reduction layer in the form of a thin film or in the form of a film, it has an effective noise reduction characteristic in the radio frequency (RF) band. In addition, according to the present invention can be applied to the thin film and built-in type without mounting the passive element in the form of a component it is effective in reducing the electromagnetic wave interference for ultra-small elements such as highly integrated circuit element. This effect enabled rapid noise countermeasures and avoided the downsizing and miniaturization of circuits. In addition, due to organic and inorganic complexation, the adhesive property of the metal and the polymer having poor adhesion is improved, and the bending property is also improved.

Claims (7)

Noise reduction film of a multilayer hybrid thin film comprising a Co-Fe-based or Co-Fe / Ni-Fe-based magnetic layer and a polyimide layer. The noise attenuation film of claim 1, wherein the multilayer hybrid thin film comprises a polyimide layer, a magnetic layer, and a polymer layer. The noise reduction film of claim 1, wherein a Co / Fe molar ratio of the Co—Fe-based magnetic layer is in a range of 10 to 90%. The noise reduction film of claim 1, wherein the polyimide layer is formed by thermal or photoreaction of the coated polyamic acid layer. The noise damping film of claim 1, wherein a Ni / Fe molar ratio of the Ni—Fe magnetic layer is in a range of 10 to 90%. The circuit board of claim 1, wherein the noise reduction film is formed on a surface or embedded therein. The polymer film of claim 1, wherein the noise reduction film is formed on a surface or embedded therein.

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