TWM594790U - Insulating soft magnetic film - Google Patents

Abstract

This creation proposes an insulating soft magnetic film that includes an insulating soft magnetic film that includes a resin layer, wherein the insulating soft magnetic film directly covers a circuit pattern provided on the surface of a circuit board and contacts the circuit pattern. The insulating soft magnetic film is an electrically insulating wave absorbing layer, especially when covered on the circuit pattern of the circuit board, it will not cause a short circuit of the circuit, and has a large wave absorbing effect in the high frequency band, making the circuit covered with the wave absorbing layer The board can effectively eliminate the electromagnetic interference in the high frequency band.

Description

Insulated soft magnetic film

This creation is about an insulating soft magnetic film, especially refers to an insulating soft magnetic film used to prevent electromagnetic interference (Electromagnetic Interference, EMI).

Most of the motherboards (usually printed circuit boards) installed on the currently used host devices have electronic components such as a central processor that are prone to emit high-frequency noise, as well as many other components (such as chips) and other components that are susceptible to external interference. Circuit. In order to prevent electronic components from interfering with the operation of other components and circuits, as well as avoiding mutual interference between electronic components and other components and circuits, electromagnetic interference prevention is needed to protect electronic components and other components and circuits.

The motherboard is usually equipped with a large number of circuits to form a circuit pattern. One of the ways to prevent electromagnetic interference is to directly cover the circuit of the motherboard with the shielding layer and set it between high-frequency electronic components and other components. One of the currently known shielding methods for electromagnetic interference prevention is to use conductive ink, usually composed of conductive particles, resin and solvent, to cover the entire electronic component or wafer to form a conductive layer to serve as an electromagnetic interference shielding layer . However, the electromagnetic wave shielded by the electromagnetic interference shielding layer in the high frequency band (not less than 1 GHz) is not absorbed and eliminated, so high-frequency electronic components and other components will interfere with each other, which instead forms a new electromagnetic interference . Moreover, it is difficult to avoid that the electromagnetic interference shielding layer formed by the conductive layer can easily cover two adjacent circuits around the electronic component or the wafer at the same time, which causes a short circuit of the circuit and causes the motherboard to report Waste. Furthermore, according to the test of international standard IEC62333, the S21 parameter is the transmission coefficient and the S11 parameter is the reflection coefficient. Although the test results of the electromagnetic interference shielding layer have a large S21 shielding effect in the high frequency band (not less than 1.0 GHz), S11 approaches At zero, this means that the electromagnetic wave is not completely attenuated by the electromagnetic interference shielding layer, 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 band.

This creative department considers the above situation and aims to provide an insulating soft magnetic film. 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 there is a large attenuation signal in the high frequency band (not less than 1.0 GHz), so that the circuit board covered with the insulating soft magnetic film (wave absorbing layer) can effectively eliminate the electromagnetic interference received in the high frequency band.

This creation proposes an insulating soft magnetic film, which includes a resin layer, wherein the insulating soft magnetic film directly covers a circuit pattern disposed on the surface of a circuit board and contacts the circuit pattern.

The aforementioned insulating soft magnetic film, wherein the insulating soft magnetic film further includes a plurality of insulating soft magnetic particles distributed on the resin layer, each of the insulating soft magnetic particles has a core portion and a shell portion surrounding the core portion, the insulating soft magnetic film The shape of the particles is spherical, and the particle size is between 1 μm and 50 μm . The core part is a ferrosilicon chromium alloy ball, and the shell part is a phosphate film, a silicate film, or a silicon dioxide film. The shell insulation resistance value larger than the portion of 5x10 ⁹ Ω; of the shell portion of the resin layer and the different-based material formed, wherein 1% to 10% by weight for the weight of the shell portion of the core portion.

In the aforementioned insulating soft magnetic film, wherein the plurality of insulating soft magnetic particles and the resin layer are measured at 100 wt%, the insulating soft magnetic film includes a plurality of 55.56~95.74 wt% of the plurality of insulating soft magnetic particles.

In the aforementioned soft magnetic insulating film, the resin layer is composed of a first resin and a second resin, the material of the shell, 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%. 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 system is a phenol epoxy resin, and the second resin system is a polymer of phenol and formaldehyde glycidyl ether.

The insulating soft magnetic film provided by this work, for the electromagnetic waves radiated in the high frequency band (not less than 1GHz), the electromagnetic wave will be absorbed and attenuated by the magnetic material contained in the insulating soft magnetic film, so in the high frequency band (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 of about 1~15dB; when the thickness of the insulating soft magnetic film is 2.6mm, S11 (reflection Coefficient) presents a reflection attenuation effect of up to 20dB at 2.64GHz. Therefore, the host board covered with the insulating soft magnetic ink and the insulating soft magnetic film provided by this creation can effectively eliminate the electromagnetic interference received in the high frequency band. However, the conventional electromagnetic interference shielding layer shows that S11 is almost zero at a high frequency band (not less than 1 GHz), indicating that it is a total reflection of electromagnetic waves without 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 1.0 GHz), but because S11 is approaching zero, this means that the electromagnetic wave is not completely attenuated by the electromagnetic interference shielding layer, but instead Because it is close to total reflection of electromagnetic waves, 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 band.

1: Insulated soft magnetic particles

11: Core

12: Shell

100: Insulated soft magnetic film

2: resin layer

3: circuit board

31: Circuit pattern

Figure 1 is a schematic diagram of the structure of insulating soft magnetic particles in the creation.

Figure 2 is a schematic diagram of the structure of the insulated soft magnetic film.

In order to make it easier for reviewers to understand the technical content, characteristics and effects of this creation, the presentation of the examples and comparative examples will make it clearer, but this creation is not limited by these examples. In addition, the use of "~" in this specification and the scope of patent application means that the numerical range refers to the range covering the numerical values described before and after "~" as the lower limit and the upper limit; "wt%" is used 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 patent application refers to the particle size measured by the laser particle size analyzer.

An insulating soft magnetic film in this creation is made of an insulating soft magnetic ink, the insulating soft magnetic ink contains: a plurality of insulating soft magnetic particles of 50wt% ~ 90wt%, a first resin of 3wt% ~ 30wt%, 1wt% ~ 10wt% A second resin and a solvent of 1wt% ~ 10wt%.

Please refer to FIG. 1, the aforementioned insulated soft magnetic particle 1 has a core portion 11 and a shell portion 12 surrounding the core portion. Wherein, the core 11 is a soft magnetic core composed of a soft magnetic material (ferromagnetic alloy material), and the core 11 may 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), iron-silicon-chromium alloy (Fe-Si-Cr alloy) or ferrite, etc. In terms of the magnetic properties of the original composition, iron-silicon-chromium alloy (Fe-Si-Cr alloy) is preferred. The shell 12 is made of an insulating material. The shell 12 may be a phosphate film, a silicate film, or a silicon dioxide film. The shell 12 is made up of 1% of the weight of the core 11 10% is formed by performing a surface insulation treatment, for example, the shell portion 12 is completed by phosphating the core portion 11 or coating the core portion 11 with sodium silicate salt. That is, the weight of the shell 12 is 1% to 10% of the weight of the core. The phosphating treatment uses a phosphoric acid or phosphate solution to perform a conversion reaction with iron atoms on the surface of the alloy listed in the core portion 11 to form a phosphate film. In addition, a water glass insulating material formed of sodium silicate may be directly added to the surface of the core portion 11 (Overlay Coating), and dried to remove water to form a silicate film. Furthermore, silane monomers can 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 shell portion 12 is greater than 5 GΩ (5× ^{10 9} Ω). The shape of the above-mentioned insulating soft magnetic particles 1 may be spherical, flat or fibrous, which is preferably spherical in this creation, and the particle size is between 1 μm and 50 μm, that is to say, the core 11 may be iron silicon Chromium alloy balls; and, based on the iron-silicon-chromium alloy as 100wt%, the core includes 85wt%~95wt% iron, 1wt%~10wt% silicon and 1wt%~5wt% chromium.

The aforementioned first resin may be a phenolic epoxy resin or an O-Methyl phenolic epoxy resin. Preferably, the first resin is a phenolic 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 type epoxy resin or novolak epoxy resin.

The first resin and the second resin system are different, and the material of the shell, 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 acetate or 1,1,3-trimethylcyclohexenone .

In order to improve the dispersibility of the plurality of insulating soft magnetic particles in the insulating soft magnetic ink, the insulating soft magnetic ink system may contain a dispersant. A plurality of the insulating soft magnetic particles, the first resin, the second resin, and the solvent are measured at 100 wt%, and the dispersant is 0.001 wt% to 0.01 wt%. The dispersant system can be vinyl trimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-propenyloxypropyltrimethoxysilane or 3- Mercaptopropylmethyldimethoxysilane.

In order to reduce the amount of bubbles generated by the insulating soft magnetic ink during stirring, the insulating soft magnetic ink system may contain a defoamer. A plurality of the insulating soft magnetic particles, the first resin, the second resin, and the solvent are measured at 100 wt%, and the defoamer is 0.1 wt% to 0.2 wt%. The defoamer system can be an organic silicon defoamer or a polymer defoamer.

Preparation of the insulating soft magnetic ink in this creation:

The insulating soft magnetic ink of the present creation can be manufactured by a method of manufacturing an insulating soft magnetic ink including the following steps: (1) according to the set plural pluralities of the insulating soft magnetic particles, the first resin, the second resin and the Prepare the material by weight percentage of the solvent; (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 Mix well, and optionally add appropriate dispersant and/or defoamer additives to complete the insulating soft magnetic ink.

Preparation of the insulating soft magnetic film in this creation:

The insulating soft magnetic film is prepared by the following preparation method of an insulating soft magnetic film: using a screen printing method or a doctor blade coating method of a stainless steel plate on a host circuit board without assembled wafers and components and having a circuit pattern, Apply the insulating soft magnetic ink on the circuit pattern of the host circuit board to form a coating of a predetermined size and shape, and then use an oven to dry at a predetermined temperature (for example, 150°C) for a predetermined time (for example, 30 minutes) In order to evaporate the solvent and form the sheet-shaped insulating soft magnetic film, 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. In particular, the insulating soft magnetic film 100 includes a resin layer 2, wherein the insulating soft magnetic film 100 directly covers a circuit pattern 31 provided on the surface of a circuit board 3 and In contact with the circuit pattern 31; wherein, the resin layer 2 is composed of the first resin and the second resin, and the material of the shell portion 12, the first resin, and the second resin system are different from each other.

The effect evaluation and test of the insulating soft magnetic film made by using this insulating soft magnetic ink in this creation:

The insulating soft magnetic film is evaluated by a film forming test to evaluate the film forming property; the insulating soft magnetic film is evaluated by surface resistance to assess whether the insulating soft magnetic film is electrically insulated; the insulating soft magnetic film is by absorbing baud The S11 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 cracking is found, it is determined that the film formation has failed and marked as "X"; if there is no cracking, but the surface is warped If it is bent, it is judged that the film-forming property is acceptable and marked as "△"; if there is no cracking phenomenon and no warpage, it is flat and the adhesion is good, it is judged that the film-forming property is good and marked as "○".

Surface resistance measurement:

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

Measurement of wave absorption characteristics:

The Keysight E-5071C network analyzer is used to connect two pyramid antennas with a transmission line to perform the measurement of the S21 parameter (or transmission coefficient) and S11 parameter (or reflection coefficient) at the electromagnetic wave frequency range of 2-18 GHz. 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 is the S11 parameter, the thickness of the insulating soft magnetic film is 2.6mm; The measured S11 parameters in the examples and comparative examples are negative numbers, and the negative numbers represent the electromagnetic waves 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 described later Table 1. The measurement of the S21 parameter is to place two pyramid antennas on opposite sides of the insulating soft magnetic film, and the transmission attenuation value of each frequency of the electromagnetic wave is measured as the S21 parameter, and the thickness of the insulating soft magnetic film is 1.0 mm; similarly, described later The measured S21 parameters in the examples and comparative examples in Table 1 are negative numbers. The negative numbers represent the electromagnetic waves absorbed. The maximum and minimum absolute values of the S21 parameters in this frequency band are recorded in Table 1 described later. The S11 parameter is a negative number, and the negative number represents the electromagnetic wave is absorbed, so the larger the absolute value of the S11 parameter, the table Shows that the greater the amount of electromagnetic waves absorbed by the insulating soft magnetic film, the greater the degree of electromagnetic wave reflection and attenuation by the insulating soft magnetic film. The more effectively the insulating soft magnetic film absorbs electromagnetic waves and eliminates the electromagnetic interference; similarly, the S21 parameter It is a negative number. The negative number represents the electromagnetic wave is absorbed. Therefore, the greater the maximum value of the absolute value of the S21 parameter, the greater the attenuation of the electromagnetic wave in this frequency band by the insulating soft magnetic film. The more effectively the insulating soft magnetic film shields the Electromagnetic interference. When the maximum value of the absolute value in the S21 parameter is less than 8dB, it is judged that the insulating soft magnetic film has a poor ability to shield electromagnetic waves and is marked as "X"; when the maximum value of the absolute value in the S21 parameter is greater than or equal to 8dB and less than 13.5 When dB, the ability of the insulating soft magnetic film to shield electromagnetic waves is acceptable and marked as "△"; when the maximum value of the absolute value in 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 Is good and marked as "○".

Overall evaluation results:

In the same embodiment or comparative example, if "X" appears in any of the film-forming test, surface resistance measurement, and absorption characteristic measurement, the overall evaluation result is bad, and is recorded as "X"; If "△" appears in any of the film-forming test, surface resistance measurement and wave-absorbing characteristic measurement, the overall evaluation result is acceptable and recorded as "△"; film-forming test, surface resistance During the measurement and the measurement of the absorption characteristics, if "○" appears, the overall evaluation result is good and recorded as "○".

According to the manufacturing method of the insulating soft magnetic ink described above, the insulating soft magnetic ink corresponding to the respective embodiments (Example 1 to Example 9) described in Table 1 below is first prepared, and then the Preparation method of insulating soft magnetic film The insulating soft magnetic film is prepared, and then the effect evaluation and testing 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 It is a phenolic epoxy resin; the second resin is a polymer of phenol and formaldehyde glycidyl ether; the solvent is ethylene glycol butyl ether acetate. Table 1 additionally describes Comparative Example 1 and Comparative Example 2. Comparative Example 1 and Comparative Example 2 are the manufacturing method of imitating the insulating soft magnetic ink, the manufacturing method of the insulating soft magnetic film, and the evaluation and testing of the effect of the insulating soft magnetic film, in which Except that Comparative Example 2 replaces the insulating soft magnetic particles of the embodiments with conductive particles, the same points will not be repeated.

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; and 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 is a total reflection of electromagnetic waves without the effect of 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 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) or even as high as 20.69dB (Example 6), indicating that the electromagnetic wave is affected by the insulating soft magnetic of Examples 1-9 The degree of film reflection attenuation is large. The insulating soft magnetic films of Examples 1 to 9 can effectively eliminate the electromagnetic interference received, so no new electromagnetic interference will be generated.

In addition, the electromagnetic interference shielding layer of Comparative Example 2 and the insulating soft magnetic film of Comparative Example 1 have cracks on the surface, and the cracks are likely to cause electromagnetic wave leakage, which may lead to the risk of failure of electromagnetic interference prevention. The insulating soft magnetic films of Examples 1 to 9 have no cracks, thus reducing the risk of electromagnetic wave leakage.

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

Of course, it can be known from the S11 parameters of Examples 1-9 in Table 1 that the insulating soft magnetic film has different contents of the insulating soft magnetic particles, and can be at different frequencies (from 2.0 GHz in Examples 7-9 to Example 1). 5.60GHz) exhibits a reflection attenuation effect. Therefore, the insulating soft magnetic ink with different contents of the insulating soft magnetic particles and the insulating soft magnetic film made using the insulating soft magnetic ink have the effect of absorbing electromagnetic waves.

In particular, the aforementioned preparation method of the insulating soft magnetic film evaporates the solvent of the insulating soft magnetic ink in the coating to form the insulating soft magnetic film, so after removing the solvent from the embodiments in Table 1, The proportions of the plurality of 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.

Based on Table 2, the plurality of insulating soft magnetic particles, the first resin and the second resin are measured at 100 wt%. The insulating soft magnetic film contains: 55.56~95.74 wt% of the plural 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 absolute The edge soft magnetic film contains 55.56~95.74wt% of the plurality of insulating soft magnetic particles and 4.07~44.44wt% of the resin layer.

The above is only the preferred embodiment of this creation, and it should not be used to limit the scope of implementation of this creation. Any simple and equivalent modifications and changes made in accordance with the scope of the patent application for this creation and the content of the new specification shall still fall within the scope of this patent for creation.

100: Insulated soft magnetic film

2: resin layer

3: circuit board

31: Circuit pattern

Claims (5)

An insulating soft magnetic film includes a resin layer, wherein the insulating soft magnetic film directly covers a circuit pattern disposed on a surface of a circuit board and contacts the circuit pattern. The insulating soft magnetic film as described in item 1 of the patent application range, wherein the insulating soft magnetic film further includes an insulating soft magnetic particle distributed on the resin layer, the insulating soft magnetic particle has a core portion and a surrounding portion surrounding the core portion The shell part, the shape of the insulating soft magnetic particles is spherical, the particle size is between 1 μ m ~ 50 μ m, the core part is iron silicon chromium alloy ball, the shell part is phosphate coating, silicate coating or two silicon oxide film, the insulation resistance of the shell portion is larger than 5x10 ⁹ Ω; of the shell portion of the resin layer and the different-based material formed, wherein the weight of the shell portion that 1% to 10% by weight of the core. The insulating soft magnetic film as described in item 2 of the patent application scope, wherein a plurality of the insulating soft magnetic particles and the resin layer are measured at 100 wt%, the insulating soft magnetic film includes a plurality of 55.56~95.74 wt% of the plurality of insulating soft magnetic films Particles. The insulating soft magnetic film as described in item 3 of the patent application range, wherein the resin layer is composed of a first resin and a second resin, and the material of the shell portion, the first resin and the second resin are not mutually The same; and the plurality of the insulating soft magnetic particles, the first resin and the second resin are measured as 100wt%, the insulating soft magnetic film contains 3.06~33.33wt% of the first resin and 1.01~11.11wt% of the Second resin. The insulating soft magnetic film as described in item 4 of the patent application range, wherein the first resin is a phenol epoxy resin, and the second resin is a polymer of phenol and formaldehyde glycidyl ether.

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