TWI718628B - Insulating soft magnetic ink and insulating soft magnetic film - Google Patents

Abstract

The present invention provides an insulating soft magnetic ink, comprising: a plurality of insulating soft magnetic particles of 50wt% to 90wt%, a first resin of 3wt% to 30wt%, a second resin of 1wt% to 10wt%, and a resin of 1wt% to 10wt% A solvent; wherein the insulating soft magnetic particles have a core and a shell surrounding the core; the shell material, the first resin and the second resin are different from each other. The insulating soft magnetic ink is used to make an insulating soft magnetic film. The insulating soft magnetic film is an electrically insulating wave-absorbing layer, especially when it is covered on the circuit pattern of the circuit board, it will not cause the short circuit of the circuit, and has a large frequency in the high frequency range. The wave-absorbing effect makes the circuit board covered with the wave-absorbing layer can effectively eliminate the electromagnetic interference in the high frequency range.

Description

Insulating soft magnetic ink and insulating soft magnetic film

The present invention relates to an insulating soft magnetic ink formed by dispersing insulating soft magnetic particles in a resin and a solvent, and an insulating soft magnetic film prepared after the insulating soft magnetic ink is coated and the solvent is removed, in particular, it refers to a type for electromagnetic interference ( Electromagnetic Interference, EMI) anti-control insulating soft magnetic ink and insulating soft magnetic film.

At present, the motherboard (usually a printed circuit board) mounted on a commonly used host device usually has electronic components such as a central processing unit that are prone to high-frequency noise, as well as many other components (such as chips) that are susceptible to external interference. Circuit. In order to prevent electronic components from interfering with the operation of other components and circuits, and to avoid mutual interference between electronic components and other components and circuits, electromagnetic interference prevention is required to protect the electronic components and other components and circuits.

Motherboards are usually equipped with many circuits to form circuit patterns. One of the ways to prevent electromagnetic interference is to directly cover the circuit of the motherboard with a shielding layer and set it between high-frequency electronic components and other components. One of the currently known ways to set up a shielding layer for electromagnetic interference prevention is to use a conductive ink usually composed of conductive particles, resin and solvent, and cover the entire electronic component or chip to form a conductive layer as an electromagnetic interference shielding layer. . However, the electromagnetic waves shielded by the electromagnetic interference shielding layer in the high frequency range (not less than 1GHz) are not absorbed and eliminated, so high-frequency electronic components and other components will interfere with each other, which instead forms a new electromagnetic interference. . What's more, it is difficult to avoid that the conductive ink can easily cover two adjacent circuits around the electronic component or chip at the same time, which causes a short circuit of the circuit and causes the motherboard to be scrapped. For the same reason, the conductive ink cannot cover a large area on the circuit pattern. Therefore, the conductive ink has limitations on its use. In fact, it is not completely suitable for the electromagnetic interference prevention of the circuit pattern. Furthermore, according to the test of the international standard IEC62333, the S21 parameter is the transmission coefficient and the S11 parameter is the reflection coefficient. The test result of the electromagnetic interference shielding layer formed by conductive ink, although there is a large S21 in the high frequency band (not less than 1.0GHz) The shielding effect, but S11 is close to zero, which means that the electromagnetic wave is not attenuated by the electromagnetic interference shielding layer at all, but because it is close to total reflection, new electromagnetic interference may be formed. Therefore, the motherboard covered with the aforementioned electromagnetic interference shielding layer cannot effectively eliminate the electromagnetic interference received in the high frequency range.

The present invention takes the above situation into consideration, and aims to provide an insulating soft magnetic ink and an insulating soft magnetic film made by using the insulating soft magnetic ink. When the insulating soft magnetic film is an electrical insulation system (the surface resistance value of not less than 1.0x10 ⁹ ohms / square (Ω / □)) of the electromagnetic wave absorbing layer, in particular a large area covering the circuit pattern on the circuit board, not It causes a short circuit of the circuit and a large attenuation signal in the high frequency band (not less than 1.0GHz), so that the circuit board covered with the insulating soft magnetic film (wave-absorbing layer) can effectively eliminate the electromagnetic interference in the high frequency band.

The present invention provides an insulating soft magnetic ink, comprising: a plurality of insulating soft magnetic particles of 50wt% to 90wt%, a first resin of 3wt% to 30wt%, a second resin of 1wt% to 10wt%, and a resin of 1wt% to 10wt% A solvent; wherein the insulating soft magnetic particles have a core and a shell surrounding the core; the shell material, the first resin and the second resin are different from each other. In this specification and the scope of patent application, "wt%" is used to refer to weight percentage.

In the aforementioned insulating soft magnetic ink, the second resin is a polymer of phenol and formaldehyde glycidyl ether.

In the aforementioned insulating soft magnetic ink, the solvent is ethylene glycol butyl ether acetate.

In the aforementioned insulating soft magnetic ink, the core is iron-silicon-chromium alloy, and the iron-silicon-chromium alloy is 100wt% as the measurement. The core contains 85wt%~95wt% iron, 1wt%~10wt% silicon and 1wt%~ 5wt% chromium.

In the aforementioned insulating soft magnetic ink, the shell part is a phosphate film, a silicate film or a silicon dioxide film.

In the aforementioned insulating soft magnetic ink, the insulation resistance value of the shell portion is greater than 5× ^{10 9} Ω.

In the aforementioned insulating soft magnetic ink, the shape of the insulating soft magnetic particles is spherical, and the particle diameter is between 1 μm and 50 μm.

In the aforementioned insulating soft magnetic ink, the insulating soft magnetic ink may contain a dispersant, and the amount of the dispersant is 0.001 by taking a plurality of the insulating soft magnetic particles, the first resin, the second resin, and the solvent as 100% by weight. wt%~0.01wt%, the dispersant is 3-glycidoxypropyltrimethoxysilane.

In the aforementioned insulating soft magnetic ink, the insulating soft magnetic ink may contain a defoaming agent, and the defoaming agent is based on a plurality of the insulating soft magnetic particles, the first resin, the second resin, and the solvent being 100% by weight. The defoamer is 0.1wt%~0.2wt%. The defoamer can be an organosilicon defoamer or a polymer defoamer.

In the aforementioned insulating soft magnetic ink, the shell portion is formed by performing a surface insulation treatment of about 1%-10% of the weight of the core portion 11.

The present invention further provides an insulating soft magnetic film, which includes a resin layer and a plurality of insulating soft magnetic particles dispersed in the resin layer; wherein the insulating soft magnetic particles have a core and a shell surrounding the core, The shape of the insulating soft magnetic particles is spherical, with a particle size ranging from 1 μm to 50 μm. The core part is an iron-silicon-chromium alloy ball. The shell part is a phosphate film, a silicate film or a silicon dioxide film. The insulation resistance value of is greater than 5x10 ⁹ Ω; the shell and the resin layer are made of different materials.

In the aforementioned insulating soft magnetic film, the weight of the shell portion is 1%-10% of the weight of the core portion.

In the aforementioned insulating soft magnetic film, a plurality of the insulating soft magnetic particles and the resin layer are 100 wt% as a measurement, and the insulating soft magnetic film contains 55.56 to 95.74 wt% of the plurality of insulating soft magnetic particles.

In the aforementioned insulating soft magnetic film, wherein the resin layer is composed of a first resin and a second resin, the material of the shell part, the first resin and the second resin are different from each other; and a plurality of the insulating The soft magnetic particles, the first resin, and the second resin are measured at 100 wt%, and the insulating soft magnetic film includes 3.06 to 33.33 wt% of the first resin and 1.01 to 11.11 wt% of the second resin.

In the aforementioned insulating soft magnetic film, the first resin is a novolac epoxy resin, and the second resin is a polymer of phenol and formaldehyde glycidyl ether.

The insulating soft magnetic film provided by the present invention, for electromagnetic waves radiated in the high frequency range (not less than 1GHz), the electromagnetic waves will be absorbed and attenuated by the magnetic material contained in the insulating soft magnetic film, so in the high frequency range (not less than 1GHz) ) Shows excellent S21 (transmission coefficient) shielding effect. When the thickness of the insulating soft magnetic film is 1mm, S21 has a shielding attenuation effect of about 1~15dB; when the thickness of the insulating soft magnetic film is 2.6mm, S11 (reflective Coefficient) exhibits a reflection attenuation effect that can reach more than 20dB at 2.64GHz. Therefore, the motherboard covered with the insulating soft magnetic ink and the insulating soft magnetic film provided by the present invention can effectively eliminate the electromagnetic interference suffered in the high frequency range. However, the conventional electromagnetic interference shielding layer shows that S11 is almost zero in the high frequency band (not less than 1 GHz), which means that it totally reflects electromagnetic waves without having the effect of absorbing (not absorbing electromagnetic waves). Although the electromagnetic interference shielding layer has a large S21 shielding effect in the high frequency band (not less than 1.0GHz), because S11 is close to zero, this means that the electromagnetic wave is not attenuated by the electromagnetic interference shielding layer at all, but because it is close to the total reflection of the electromagnetic wave It may form a new electromagnetic interference. Therefore, the motherboard covered with the aforementioned electromagnetic interference shielding layer cannot effectively eliminate the electromagnetic interference received in the high frequency range.

In order to make it easier for the examiner to understand the technical content, features and effects of the present invention, it will be explained more clearly in conjunction with the presentation of the embodiments and comparative examples, but the present invention is not limited by these embodiments. In addition, the use of "~" in this specification and the scope of patent application indicates that the numerical range refers to the range that covers the values before and after the "~" as the lower limit and upper limit; the use of "wt%" in this specification and the scope of patent application , Refers to the weight percentage; the "particle size" used in this specification and the scope of the patent application refers to the particle size measured by a laser particle size analyzer.

This creation is an insulating soft magnetic ink, which contains: 50wt%~90wt% of a plurality of insulating soft magnetic particles, 3wt%~30wt% of a first resin, 1wt%~10wt% of a second resin and 1wt%~10wt% of One solvent.

Please refer to Figure 1. The aforementioned insulating soft magnetic particle 1 has a core 11 and a shell 12 surrounding the core. Wherein, the core 11 is a soft magnetic core composed of a soft magnetic material (ferromagnetic alloy material), and the core 11 can be: magnetic stainless steel (Fe-Cr-Al-Si alloy), iron-silicon aluminum alloy (Fe -Si-Al alloy), nickel-iron alloy (Fe-Ni alloy), iron-silicon-copper alloy (Fe-Cu-Si alloy), iron-silicon alloy Fe-Si alloy, iron-silicon chromium-nickel alloy (Fe-Si-Cr-Ni) Alloy), Fe-Si-Cr alloy (Fe-Si-Cr alloy) or ferrite, etc., and in terms of the magnetic characteristics of the present invention, Fe-Si-Cr alloy (Fe-Si-Cr alloy) is preferred. The shell portion 12 is made of an insulating material. The shell portion 12 can be: a phosphate film, a silicate film or a silicon dioxide film. The shell portion 12 is made of 1% of the weight of the core 11~ 10% is formed by performing a surface insulation treatment, for example, the shell part 12 is formed by phosphating the core part 11 or coating the core part 11 with sodium silicate. In other words, the weight of the shell portion 12 is 1%-10% of the weight of the core portion. The aforementioned phosphating treatment utilizes phosphoric acid or a phosphate solution to carry out a conversion reaction (Conversion Reaction) reaction with the iron atoms on the surface of the alloy listed in the aforementioned core portion 11 to form a phosphate film. In addition, the water glass insulating material formed by sodium silicate salt can be directly added to overlay (Overlay Coating) on the surface of the core 11 and dried to remove water to form a silicate film. Furthermore, silane monomers can also be polymerized to form polysiloxane molecules, which are then directly added to coat the surface of the core 11, and dried to remove water to form a silicon dioxide film. In particular, the insulation resistance value of the aforementioned shell portion 12 is greater than 5 GΩ (5× ^{10 9} Ω). The shape of the aforementioned insulating soft magnetic particles 1 can be spherical, flat or fibrous. In the present invention, the shape is preferably spherical, and the particle size is between 1 μm and 50 μm. That is to say, the core 11 can be ferrosilicon. Chromium alloy ball; and, based on the iron-silicon-chromium alloy as 100wt%, the core contains 85wt%~95wt% iron, 1wt%~10wt% silicon and 1wt%~5wt% chromium.

The aforementioned first resin may be phenolic epoxy resin or O-Methyl phenolic epoxy resin. Preferably, the first resin is novolac epoxy resin.

The aforementioned second resin may be a polymer of phenol and formaldehyde glycidyl ether (CAS Number: 28064-14-4) (Phenol polymer with formaldehyde glycidyl ether), bisphenol F epoxy resin or linear aldehyde epoxy resin.

The first resin and the second resin system are different, and the material of the shell part, the first resin and the second resin system are different from each other.

The aforementioned solvent can be ethylene glycol butyl ether acetate, ethylene glycol ethyl ether acetate, diethylene glycol butyl ether acetate, diethylene glycol ethyl ether acetic acid or 1,1,3-trimethylcyclohexenone .

In order to improve the dispersibility of the insulating soft magnetic particles in the insulating soft magnetic ink, the insulating soft magnetic ink may contain a dispersant. Taking a plurality of the insulating soft magnetic particles, the first resin, the second resin, and the solvent as 100 wt% as a measurement, the dispersant system is 0.001 wt% to 0.01 wt%. The dispersant system can be vinyl trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, p-styryl trimethoxysilane, 3-propenoxypropyl trimethoxysilane or 3- Mercaptopropylmethyldimethoxysilane.

In order to reduce the amount of bubbles generated in the insulating soft magnetic ink during the stirring process, the insulating soft magnetic ink may contain a defoaming agent. Taking a plurality of the insulating soft magnetic particles, the first resin, the second resin, and the solvent as 100 wt%, the defoaming agent is 0.1 wt% to 0.2 wt%. The defoaming agent can be an organosilicon defoaming agent or a polymer defoaming agent.

The preparation of the insulating soft magnetic ink of the present invention:

The insulating soft magnetic ink of the present invention can be manufactured by a manufacturing method of insulating soft magnetic ink including the following steps: (1) According to a set of a plurality of the insulating soft magnetic particles, the first resin, the second resin and the The weight percentage of the solvent to prepare the material; (2) Mix a plurality of the insulating soft magnetic particles, the first resin, the second resin and the solvent at room temperature with a planetary mixer to stir and mix evenly, and optionally add appropriate Dispersant and/or defoamer additives to complete the insulating soft magnetic ink.

The preparation of the insulating soft magnetic film of the present invention:

The insulating soft magnetic film is prepared by the following preparation method of the insulating soft magnetic film: using a screen printing method or a stainless steel plate scraper coating method on a host circuit board that has not assembled chips and components and has a circuit pattern, The insulating soft magnetic ink is coated on the circuit pattern of the host circuit board to form a coating of a predetermined size and shape, and then dried in an oven at a predetermined temperature (such as 150 ^o C) for a predetermined time (such as 30 minutes) ) To volatilize the solvent to form the insulating soft magnetic film in a sheet shape, the thickness of the insulating soft magnetic film is 100 μm ~ 2.6 mm; preferably, the thickness of the insulating soft magnetic film is 100 μm ~ 300 μm. Please refer to FIG. 2 together. It is particularly noted that the insulating soft magnetic film 100 includes a resin layer 2 and a plurality of the insulating soft magnetic particles 1 dispersed in the resin layer; wherein, the resin layer 2 is formed by the first resin layer 2 It is composed of a resin and the second resin, and the material of the shell portion 12, the first resin and the second resin are different from each other.

The effect evaluation and test of the insulating soft magnetic film made by using the insulating soft magnetic ink of the present invention:

The insulating soft magnetic film is evaluated by film-forming property test; the insulating soft magnetic film is measured by surface resistance to evaluate whether the insulating soft magnetic film is electrically insulated; the insulating soft magnetic film is evaluated by attracting The S11 parameters and S21 parameters are measured to evaluate the amount of electromagnetic waves absorbed by the insulating soft magnetic film.

Film formation test:

Observe the surface of the insulating soft magnetic film by visual inspection: if cracks are found, it is judged as film-forming failure and marked as "X"; if there is no cracking, but the surface is warped, it is judged as film-forming Acceptable and marked as "△"; if there is no cracking, no warpage, flat and good adhesion, it is judged as good film formation and marked as "○".

Surface resistance measurement:

The surface resistance of the insulating soft magnetic film is measured by a four-point probe measurement method for the above-mentioned insulating soft magnetic film. After measuring a total of 5 points on the insulating soft magnetic film, the average value is taken as the recorded surface resistance value. When the surface resistance value is not less than 1.0x10 ⁹ ohm/square (Ω/□), it is judged as electrical insulation and marked as "○"; when the surface resistance value is not less than 1.0 ohm/square (Ω/□), it is judged It is non-electrically insulated and marked as "X", which means that it does not meet the electrical insulation conditions of the insulating soft magnetic film.

Absorption characteristics measurement:

The Keysight E-5071C network analyzer is used to connect two pyramid antennas with a transmission line to perform the measurement of S21 parameters (or transmission coefficient) and S11 parameters (or reflection coefficient) in the electromagnetic wave frequency band of 2-18GHz. Among them, the measurement of the S11 parameter is to place two pyramid antennas on the same side of the insulating soft magnetic film to measure the electromagnetic wave reflection attenuation value as the S11 parameter. The thickness of the insulating soft magnetic film is 2.6mm; The measured S11 parameter in the embodiment and the comparative example is a negative number, which means electromagnetic waves are absorbed. The frequency value (GHz) at which the S11 parameter reaches the maximum value and the absolute value of the S11 parameter value (dB) at this time are recorded in the following Table one. The measurement of S21 parameter is to place two pyramid antennas on the opposite side of the insulating soft magnetic film to measure the transmission attenuation value of each frequency of the electromagnetic wave, which is the S21 parameter. The thickness of the insulating soft magnetic film is 1.0mm; similarly, described later The measured S21 parameters in the examples and comparative examples in Table 1 are negative numbers, which represent electromagnetic waves are absorbed. The maximum and minimum absolute values of the S21 parameters in this frequency band are recorded in Table 1 below. The S11 parameter is a negative number. A negative number means electromagnetic waves are absorbed. Therefore, the larger the absolute value of the S11 parameter, the greater the amount of electromagnetic waves absorbed by the insulating soft magnetic film, and the greater the degree of reflection and attenuation of electromagnetic waves by the insulating soft magnetic film. The more effective the insulating soft magnetic film absorbs electromagnetic waves and eliminates electromagnetic interference. Similarly, the S21 parameter is a negative number, which means electromagnetic waves are absorbed. Therefore, the greater the absolute value of the S21 parameter, the greater the maximum value of the electromagnetic wave in this frequency band. The greater the degree of shielding attenuation of the insulating soft magnetic film, the more effectively the insulating soft magnetic film shields the electromagnetic interference received. When the maximum value of the absolute value of the S21 parameter is less than 8dB, it is determined that the insulating soft magnetic film has poor electromagnetic shielding ability and marked as "X"; when the maximum value of the absolute value of the S21 parameter is greater than or equal to 8dB and less than 13.5 dB, the ability of the insulating soft magnetic film to shield electromagnetic waves is determined to be acceptable and marked as "△"; when the maximum absolute value of the S21 parameter is greater than or equal to 13.5dB, the ability of the insulating soft magnetic film to shield electromagnetic waves is determined It is good and marked as "○".

Overall assessment results:

In the same embodiment or comparative example, if an "X" appears in any of the film formation test, the surface resistance measurement, and the measurement of the wave absorption characteristic, the overall evaluation result is bad and recorded as "X"; If “△” appears in any of the film formation test, surface resistance measurement, and absorption characteristic measurement, the overall evaluation result is acceptable and recorded as “△”; film formation test, surface resistance In the measurement and the measurement of the absorption characteristics, if both "○" appear, the overall evaluation result is good and recorded as "○".

According to the manufacturing method of the insulating soft magnetic ink of the present invention, the insulating soft magnetic ink is firstly prepared into the insulating soft magnetic ink corresponding to the respective embodiments (Example 1 to Example 9) described in Table 1 below, and then by the Preparation method of insulating soft magnetic film The insulating soft magnetic film is prepared, and then the effect evaluation and test of the insulating soft magnetic film are performed, and the results are recorded in Table 1. Among them, the core of the insulating soft magnetic particles in Table 1 is iron-silicon-chromium alloy, and the shell is a phosphate film; the first resin is a phenolic epoxy resin; the second resin is a polymerization of phenol and formaldehyde glycidyl ether物; The solvent is ethylene glycol butyl ether acetate. Table 1 additionally records Comparative Example 1 and Comparative Example 2. Comparative Example 1 and Comparative Example 2 imitate the manufacturing method of the insulating soft magnetic ink, the preparation method of the insulating soft magnetic film, and the evaluation and testing of the effect of the insulating soft magnetic film. Except that Comparative Example 2 uses conductive particles to replace the insulating soft magnetic particles of each embodiment, the remaining similarities will not be repeated.

Table I project Composition of insulating soft magnetic ink (wt%) The characteristics of the insulating soft magnetic film (Comparative Example 1 and Examples 1-9) The characteristics of the electromagnetic interference shielding layer (Comparative Example 2) Conductive particles Insulating soft magnetic particles The first resin Second resin Solvent Add up Film forming Surface resistance Ω/□ Absorption characteristics@2~18GHz Overall assessment result S11 absolute frequency value (GHz) parameter value (dB) S21 absolute value minimum (dB) ~ maximum (dB) Example 1 0 50 30 10 10 100 △ ○ greater than 10 ¹⁰ 5.60GHz 8.39dB △ 1.17~8.23 △ Example 2 0 60 20 10 10 100 △ ○ greater than 10 ¹⁰ 4.30GHz 10.16dB △ 1.41~9.88 △ Example 3 0 70 10 10 10 100 △ ○ greater than 10 ¹⁰ 3.20GHz 12.56dB △ 1.64~11.5 △ Example 4 0 80 3 10 7 100 △ ○ greater than 10 ¹⁰ 2.50GHz 16.33dB △ 1.88~13.1 △ Example 5 0 84 9 4 3 100 △ ○ greater than 10 ¹⁰ 2.75GHz 18.12dB ○ 1.95~13.7 △ Example 6 0 85 9 3 3 100 ○ ○ 1x10 ¹⁰ 2.64GHz 20.69dB ○ 2.0~14.0 ○ Example 7 0 90 3 1 6 100 ○ ○ 5x10 ⁹ 2.0GHz 18.1dB ○ 2.1~14.7 ○ Example 8 0 90 3 5 2 100 ○ ○ 5x10 ⁹ 2.0GHz 18.3dB ○ 2.1~14.7 ○ Example 9 0 90 8 1 1 100 ○ ○ 5x10 ⁹ 2.0GHz 18.2dB ○ 2.1~14.7 ○ Comparative example 1 0 95 3 1 1 100 X ○ 5x10 ⁹ 1.56GHz 12.6dB △ 2.4~12.5 X Comparative example 2 90 0 8 1 1 100 X X 1x10 ⁰ 5.60GHz 0.56dB X 2.15~7.30 X

As shown in Table 1, the overall evaluation results are: the overall evaluation results of Comparative Examples 1 and 2 are bad; the overall evaluation results of Examples 1 to 5 are acceptable; the overall evaluation results of Examples 6 to 9 are good.

Comparative example 2 is a conventional electromagnetic interference shielding layer. Under high frequency electromagnetic waves, the electromagnetic interference shielding layer shows that the absolute value of the S11 parameter is almost zero (0.56dB), which means that it totally reflects electromagnetic waves without absorbing electromagnetic waves. , It also means that the electromagnetic wave is not attenuated by the electromagnetic interference shielding layer at all, but because it is close to the total reflection of the electromagnetic wave, new electromagnetic interference may be formed. The absolute value of the S11 parameter of the insulating soft magnetic film of Examples 1-9 is at least 8.39dB (Example 1) and even as high as 20.69dB (Example 6), indicating that electromagnetic waves are affected by the insulating soft magnetic film of Examples 1-9. The degree of film reflection attenuation is large, and the insulating soft magnetic film of Examples 1-9 can effectively eliminate the electromagnetic interference received, so no new electromagnetic interference will be generated.

Furthermore, the surface of the electromagnetic interference shielding layer of Comparative Example 2 and the insulating soft magnetic film of Comparative Example 1 have cracks, and the cracks are likely to cause electromagnetic wave leakage, which may lead to the risk of failure of electromagnetic interference control. The insulating soft magnetic films of Examples 1-9 have no cracks, so the risk of electromagnetic wave leakage is reduced.

In addition, the surface resistance value of Comparative Example 2 is 1x10 ⁰ Ω/□, which has conductive properties. Therefore, when it is directly covered on the circuit pattern on the host circuit board, the circuit will be short-circuited and the host circuit board will be scrapped. The surface resistance of the insulating soft magnetic film of Examples 1-9 is at least 5× ^{10 9} Ω/□, so it can directly cover the circuit pattern on the host circuit board without causing short circuit of the circuit.

Of course, from the S11 parameters of Examples 1 to 9 in Table 1, the insulating soft magnetic film has a different content of the insulating soft magnetic particles and can operate at different frequencies (from 2.0 GHz in Examples 7 to 9 to Example 1 (5.60GHz) shows the reflection attenuation effect, so the insulating soft magnetic ink with different contents of the insulating soft magnetic particles and the insulating soft magnetic film made by using the insulating soft magnetic ink have the effect of absorbing electromagnetic waves.

In particular, the aforementioned method for preparing the insulating soft magnetic film is to volatilize the solvent of the insulating soft magnetic ink in the coating to form the insulating soft magnetic film. Therefore, after removing the solvent from the examples in Table 1, The proportions of the insulating soft magnetic particles, the first resin and the second resin in the insulating soft magnetic film are calculated and listed in Table 2 below.

Table II project Composition of insulating soft magnetic film (wt%) Insulating soft magnetic particles The first resin Second resin Example 1 55.56 33.33 11.11 Example 2 66.67 22.22 11.11 Example 3 77.78 11.11 11.11 Example 4 86.02 3.23 10.75 Example 5 86.60 9.28 4.12 Example 6 87.63 9.28 3.09 Example 7 95.75 3.19 1.06 Example 8 91.84 3.06 5.10 Example 9 90.91 8.08 1.01

Based on Table 2, taking a plurality of the insulating soft magnetic particles, the first resin and the second resin as 100wt%, the insulating soft magnetic film contains: 55.56~95.74wt% of the plurality of insulating soft magnetic particles, 3.06~ 33.33wt% of the first resin and 1.01-11.11wt% of the second resin. In other words, taking a plurality of the insulating soft magnetic particles and the resin layer as 100% by weight, the insulating soft magnetic film contains: 55.56 to 95.74% by weight of the plurality of insulating soft magnetic particles and 4.07 to 44.44% by weight of the resin layer.

The above are only preferred embodiments of this creation, and should not be used to limit the scope of implementation of this creation. All simple and equivalent modifications and changes made in accordance with the scope of the patent application for this creation and the content of the description of the invention shall still fall within the scope of the patent for this creation.

1: Insulating soft magnetic particles 11: Core 12: Shell 100: Insulating soft magnetic film 2: Resin layer

Figure 1 is a schematic diagram of the structure of insulating soft magnetic particles in the present invention. Figure 2 is a schematic diagram of the structure of the insulating soft magnetic film of the present invention.

1: Insulating soft magnetic particles

11: Core

12: Shell

100: Insulating soft magnetic film

2: Resin layer

Claims (12)

An insulating soft magnetic ink, comprising: a plurality of insulating soft magnetic particles of 50wt% to 90wt%, a first resin of 3wt% to 30wt%, a second resin of 1wt% to 10wt%, and a solvent of 1wt% to 10wt%; Wherein, the insulating soft magnetic particle has a core and a shell surrounding the core; the shell material, the first resin and the second resin are different from each other; the shell is formed by the About 1%~10% of the weight of the core is formed by a surface insulation treatment; the shell is a phosphate film, a silicate film or a silicon dioxide film; and the insulation resistance value of the shell is greater than 5x10 ⁹ Ω. The insulating soft magnetic ink described in the first item of the scope of patent application, wherein the first resin is phenolic epoxy resin. The insulating soft magnetic ink described in item 2 of the scope of patent application, wherein the second resin is a polymer of phenol and formaldehyde glycidyl ether. The insulating soft magnetic ink described in item 3 of the scope of patent application, wherein the solvent is ethylene glycol butyl ether acetate. The insulating soft magnetic ink described in item 4 of the scope of the patent application, wherein the core is iron-silicon-chromium alloy, and the iron-silicon-chromium alloy is 100wt% as the measurement, and the core contains 85wt%~95wt% iron, 1wt%~ 10wt% silicon and 1wt%~5wt% chromium. The insulating soft magnetic ink described in item 5 of the scope of patent application, wherein the insulating soft magnetic particles are spherical in shape and the particle size is between 1 μm and 50 μm. The insulating soft magnetic ink described in item 6 of the scope of patent application, wherein the insulating soft magnetic ink may contain a dispersant, and a plurality of the insulating soft magnetic particles, the first resin, the The amount of the second resin and the solvent is 100% by weight, the dispersant is 0.001% to 0.01% by weight, and the dispersant is 3-glycidoxypropyltrimethoxysilane. The insulating soft magnetic ink described in item 7 of the scope of patent application, wherein the insulating soft magnetic ink may contain a defoaming agent, and a plurality of the insulating soft magnetic particles, the first resin, the second resin and the solvent are 100wt% For measurement, the defoaming agent is 0.1wt% to 0.2wt%, and the defoaming agent can be an organosilicon defoaming agent or a polymer defoaming agent. An insulating soft magnetic film comprising a resin layer and a plurality of insulating soft magnetic particles dispersed in the resin layer; wherein the insulating soft magnetic particle has a core and a shell surrounding the core, the insulating soft magnetic particle The shape is spherical, the particle size is between 1 μm ~50 μm , the core is iron-silica-chromium alloy ball, the shell is phosphate film, silicate film or silicon dioxide film, and the shell The insulation resistance value of is greater than 5x10 ⁹ Ω; the shell and the resin layer are made of different materials; the weight of the shell is 1%-10% of the weight of the core. The insulating soft magnetic film described in item 9 of the scope of patent application, wherein a plurality of the insulating soft magnetic particles and the resin layer are 100wt% as the measurement, and the insulating soft magnetic film contains 55.56~95.74wt% of the plurality of the insulating soft magnetic Particles. The insulating soft magnetic film described in claim 10, wherein the resin layer is composed of a first resin and a second resin, and the material of the shell part, the first resin and the second resin are different from each other. The same; and taking a plurality of the insulating soft magnetic particles, the first resin and the second resin as 100wt%, the insulating soft magnetic film contains 3.06~33.33wt% of the first resin and 1.01~11.11wt% of the The second resin. The insulating soft magnetic film described in item 11 of the scope of patent application, wherein the first resin is a novolac epoxy resin, and the second resin is a polymer of phenol and formaldehyde glycidyl ether.

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