JP2004221602A - Emi-countermeasure component and active element provided therewith - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an EMI-countermeasure component which has full shielding efficiency to transmission of electromagnetic waves radiated to the outside, and further, in which mutual interference between peripheral components and malfunction due to electromagnetic induction to a signal line, etc. are suppressed, without damaging circuit function, and to provide an active element provided therewith. <P>SOLUTION: The EMI-countermeasure component is constituted by a compound magnetic substance, which contains a soft magnetic substance powder and an organic bonding material, having an oxide skin on its surface, and related to the active element provided therewith, a part of the active element is coated with the EMI-countermeasure component. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to an EMI (Electro-Magnetic Interference) countermeasure component and an active element having the same, and particularly to an EMI countermeasure component for suppressing electromagnetic radiation such as external radiation, performance degradation, and abnormal resonance caused by unnecessary electromagnetic waves in a high-frequency region. And an active element including the same.

  2. Description of the Related Art In recent years, electronic devices using high frequencies, such as digital electronic devices, have been reduced in size. In digital electronic devices having a high component mounting density on a wiring board, LSIs and ICs such as a central processing unit (CPU) and an image processor arithmetic logic unit (IPLU) are mounted on the wiring board. These LSIs and ICs are composed of a large number of semiconductor elements, and these semiconductor elements are generally referred to as active elements because they receive an external energy supply and perform operations such as amplification or oscillation. Such active elements often generate inductive noise. This inductive noise induces a high-frequency magnetic field on the same surface as the device mounting surface of the wiring board and on the opposite surface. Problems here include phenomena such as increased line-to-line coupling due to electrostatic coupling and electromagnetic coupling, performance degradation and abnormal resonance due to electromagnetic interference due to radiation noise.

  Conventionally, for such a so-called electromagnetic interference, a means of inserting a low-pass filter in a circuit, separating a problematic circuit, or performing shielding or the like is used to reduce electromagnetic coupling and unnecessary radiation noise that cause electromagnetic interference. Restrained.

  However, among the conventional measures against electromagnetic interference, the method of inserting a noise filter and the method of performing shielding require a mounting space, and cannot be said to be effective measures for realizing high density. Similarly, the method of keeping the problematic circuit away is against the densification. Furthermore, the so-called shielding method in which a problematic circuit is surrounded by a conductor such as a metal plate or conductive plating is a method that has been conventionally performed, but this method prevents leakage of radiated noise generated inside from leaking to the outside. The purpose is to prevent radiation noise from outside from entering the inside, and if the distance of the metal plate for shielding is too close, attenuation of transmission can be expected, but from unnecessary radiation sources Electromagnetic coupling due to the reflection of light is promoted, and as a result, secondary electromagnetic interference is often caused.

  Therefore, an object of the present invention is to provide a sufficient shielding effect against the transmission of electromagnetic waves radiated to the outside without impairing the original circuit function, as well as mutual interference with peripheral components and electromagnetic interference to signal lines. An object of the present invention is to provide an EMI countermeasure component capable of suppressing a malfunction or the like due to induction and an active element including the same.

  According to the first aspect of the present invention, there is provided an EMI suppression component for suppressing inductive noise radiated from an active element such as a semiconductor element, wherein the EMI suppression component is combined with a soft magnetic material powder having an oxide film on a surface by organic bonding. EMI countermeasure component characterized by being composed of a composite magnetic material containing an agent.

  According to the second aspect of the present invention, the soft magnetic powder having an oxide film on the surface has a flat shape and / or a needle shape. Is obtained.

  According to the third aspect of the present invention, the EMI countermeasure component according to the second aspect is characterized in that the flat or / and acicular soft magnetic material powders are oriented and arranged in the composite magnetic material. can get.

  According to the fourth aspect of the present invention, an exposed portion for exposing a part of the surface of the active element is formed to radiate heat from the active element. The EMI countermeasure component described in any one of the above is obtained.

  According to a fifth aspect of the present invention, there is provided an EMI suppression component, wherein any one of the EMI suppression components according to the first to fourth aspects is arranged on the upper surface of an active element such as a semiconductor. Active element is obtained.

  According to a sixth aspect of the present invention, there is provided an EMI suppression component characterized in that one of the EMI suppression components according to the first to fourth aspects is arranged on a side surface of an active element such as a semiconductor. Active element is obtained.

  According to a seventh aspect of the present invention, there is provided an EMI suppression component, wherein one of the EMI suppression components according to the first to fourth aspects is arranged on the bottom surface of an active element such as a semiconductor. Active element is obtained.

  According to an eighth aspect of the present invention, in the active element having the EMI suppression component according to the fifth aspect, the upper part of a lead wire connecting the active element and a wiring on a substrate on which the active element is mounted is formed. An active element including the EMI suppression component is obtained by disposing the EMI suppression component from the upper surface to the side surface of the active element so as to surround the EMI suppression component.

  According to the ninth aspect of the present invention, in the active element including the EMI suppression component according to the sixth aspect, a lead wire connecting the active element and a wiring on a substrate on which the active element is mounted is formed so as to surround a lead wire. An active element provided with the EMI countermeasure component, wherein the EMI countermeasure component is disposed, is obtained.

  According to the tenth aspect of the invention, by using any one of the EMI countermeasure components according to the first to fourth aspects, inductive noise radiated from an active element such as a semiconductor element is suppressed. An EMI countermeasure method characterized by the above is obtained.

  According to the EMI countermeasure component of the present invention and the active device including the same, unnecessary radiation noise generated from an active device such as a semiconductor device is generated by a composite magnetic material including a soft magnetic material powder having an oxide film on its surface and an organic binder. It is greatly suppressed by the body. This soft magnetic powder is made by finely pulverizing a soft magnetic metal, which is originally a conductive substance, and kneading it with an insulating organic binder to disperse the soft magnetic powder in the organic binder. It forms a membrane. In particular, if the shape of the soft magnetic material powder is at least one of a flat shape and a needle shape, a shape magnetic anisotropy appears, and a complex magnetic permeability based on magnetic resonance increases in a high frequency region, whereby In addition, unnecessary radiation components can be efficiently absorbed and suppressed.

  By mounting the EMI suppression component composed of the composite magnetic material of the present invention on an active element such as a semiconductor element, it is possible to effectively suppress mutual interference due to electromagnetic induction and unnecessary electromagnetic waves, and furthermore, the mounting space is reduced. Since it is not necessary, miniaturization can be achieved, which is very effective for EMI countermeasures in high-frequency devices such as mobile communication devices.

  The present invention will be described with reference to the following examples.

  Hereinafter, an EMI suppression component according to an embodiment of the present invention and an active device including the same will be described with reference to the drawings.

  FIG. 1 shows a first embodiment of the present invention. In the present embodiment, an EMI countermeasure component 2 composed of a composite magnetic material composed of a soft magnetic material powder having an oxide film on its surface and an organic binder covers from the upper surface of the LSI 1 to a portion above the lead wire (pin) 1a on the side surface. It has such a structure.

  FIG. 2 shows a second embodiment of the present invention. This embodiment is an EMI countermeasure component 2 composed of a composite magnetic body composed of a soft magnetic powder having an oxide film on its surface and an organic binder, from the peripheral portion of the upper surface of the LSI 1 to the portion above the lead wire (pin) 1a on the side surface. Are arranged so as to surround.

  In this case, the difference from the embodiment of FIG. 1 is that a notch (exposed portion) 2 a is provided in a part of the EMI countermeasure component 2 provided on the upper surface of the LSI 1 so that the inductive radiated noise is not impaired. Can be suppressed.

FIG. 3 shows a third embodiment of the present invention. In the present embodiment, an EMI countermeasure component 2 composed of a soft magnetic powder having an oxide film on its surface and a composite magnetic material composed of an organic binder is provided so as to surround a lead wire (pin) 1a on the side surface of the LSI 1. Have been. In this case, the EMI countermeasure component 2 is provided with a lead-out window 2b for the lead wire 1a at an interval such that the lead wire 1a is not in contact with the lead wire 1a of the LSI 1. Further, since the surface resistance of the composite magnetic material is as high as 10 ⁶ to 10 ⁸ Ω, it can be integrally formed with the LSI 1.

  As described above, when the EMI countermeasure component 2 is provided, the EMI countermeasure component 2 generates heat in a high frequency magnetic field generated from the back surface of the LSI 1 and the lead wire (pin) 1a by the imaginary part magnetic permeability μ ″ of the composite magnetic body. As a result, the inductive coupling between the LSI 1 and peripheral components such as a printed circuit board on which the LSI 1 is mounted and passive components is weakened, and unnecessary electromagnetic waves can be efficiently suppressed.

  Here, the composite magnetic body 2 'constituting the above-described EMI suppression component 2 will be described with reference to FIG. The composite magnetic body 2 ′ contains a soft magnetic powder 3 having an oxide film on the surface and an organic binder 4. Specifically, the soft magnetic material powder 8 is uniformly dispersed in the organic binder 4. Here, the shape of the soft magnetic powder 3 is flat or / and acicular.

  Examples of the flat (or acicular) soft magnetic powder 3 include iron aluminum silicon alloy (Sendust) and iron nickel alloy (Permalloy) having high high frequency magnetic permeability as typical materials. It is desirable that the aspect ratio of the soft magnetic powder 3 is sufficiently large (about 5: 1 or more).

  Examples of the organic binder 4 include thermoplastic resins such as polyester resin, polyvinyl chloride resin, polyvinyl butyral resin, polyurethane resin, cellulose resin, nitrile-butadiene rubber, styrene-butadiene rubber, and copolymers thereof. And thermosetting resins such as an epoxy resin, a phenol resin, an amide resin, and an imide resin.

  The thickness, constituent material, and the like of the composite magnetic body are determined so as to realize an optimal electromagnetic environment in consideration of the use state of the active element, the electromagnetic field strength, and the like.

  In order to verify the effect of the above-described embodiment on the EMI countermeasure component and the LSI having the same against electromagnetic interference, a soft magnetic paste having the composition shown in Table 1 below was prepared, and this was formed into a film by the doctor blade method. After the hot pressing, curing was performed at 85 ° C. for 24 hours to produce a first sample having a thickness of 1 mm, and its characteristics were evaluated.

When the obtained first sample was analyzed using a vibrating magnetometer and a scanning electron microscope, the easy axis of magnetization and the orientation direction of the magnetic particles were all in-plane directions of these layers. Further, when the surface resistance was measured, it was 4 × 10 ⁷ Ω.

  The EMI countermeasure component composed of the composite magnetic material of the above-described first sample is formed into the shape shown in FIGS. 1, 2, and 3, and mounted, and then the LSI is operated by a test circuit, and the upper part of the LSI is operated. The effect was confirmed by measuring the electromagnetic field intensity with a spectrum analyzer.

  Note that the measurement was also performed under the same conditions as described above even when no EMI countermeasure parts were mounted.

  5, 6, and 7 show the measurement results. FIG. 5 shows the frequency characteristics of the electromagnetic field strength above the LSI to which no EMI suppression component is mounted. FIG. 6 shows the frequency characteristics of the electromagnetic field strength on the upper part of the LSI on which the EMI suppression component having the shape of the embodiment shown in FIG. 1 is mounted. FIG. 7 shows the frequency characteristics of the electromagnetic field strength above the LSI on which the EMI suppression component having the shape of the embodiment shown in FIG. 2 is mounted. The measurement position is the same as in FIG. 5 for both FIGS.

  From the above results, it can be seen that the radiation noise from the LSI on which the EMI suppression component is mounted is greatly attenuated.

  Further, the binding level of the first sample was measured using a test apparatus shown in FIG. As a comparative sample, a copper foil of 35 μm was used as a second sample.

  The test apparatus connects an electromagnetic field transmitting micro-loop antenna 7 having a loop diameter of 2 mm or less and an electromagnetic field receiving micro-loop antenna 8 to an electromagnetic wave source oscillator 5 and an electromagnetic field strength measuring device (receiving element) 6, respectively. Device. The measurement was performed with the small loop antenna 7 for electromagnetic field transmission and the small loop antenna 8 for electromagnetic field reception facing one surface of the sample 9. Note that a spectrum analyzer (not shown) is connected to the electromagnetic field strength measuring device 6, and the electromagnetic field strength in a state where no sample exists is used as a reference.

  FIG. 9 shows the measurement results in FIG.

  Compared to the second sample (copper foil 35 μm), the first sample, which is a composite magnetic material composed of a soft magnetic powder having an oxide film on the surface and an organic binder, does not show an increase in the bonding level.

  As described above, inductive noise radiated from an active element such as a semiconductor element can be reduced by mounting an EMI countermeasure component composed of a composite magnetic material including a soft magnetic material powder having an oxide film on its surface and an organic binder. It can be suppressed effectively.

  The present invention relates to an electronic device utilizing high frequency, a central processing unit (CPU) and an image processor arithmetic logic unit (IPLU) of a digital electronic device having a high component mounting density on a wiring board, and an LSI or an IC mounted on the wiring board. It is implemented and used above.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a first embodiment of an LSI including an EMI suppression component constituted by a composite magnetic body according to an embodiment of the present invention. FIG. 7 is a perspective view showing a second embodiment of an LSI including an EMI suppression component constituted by a composite magnetic body according to an embodiment of the present invention. FIG. 11 is a perspective view illustrating a third embodiment of an LSI including an EMI suppression component constituted by a composite magnetic body according to an embodiment of the present invention. FIG. 4 is a partially enlarged cross-sectional view of a composite magnetic body constituting the EMI suppression component shown in FIGS. 1 to 3. FIG. 4 is a diagram illustrating frequency characteristics of electromagnetic field strength on the upper surface side of an LSI (active element) on which a composite magnetic body is not mounted. FIG. 2 is a diagram illustrating a frequency characteristic of an electromagnetic field intensity on an upper surface side of an LSI (active element) on which an EMI suppression component is mounted as illustrated in FIG. 1. FIG. 3 is a diagram illustrating a frequency characteristic of an electromagnetic field intensity on an upper surface side of an LSI (active element) on which an EMI suppression component is mounted as illustrated in FIG. 2. It is a figure for explaining the measuring method for verifying the characteristic of the composite magnetic body which constitutes the EMI measures part, and is a schematic diagram showing the evaluation system of the coupling level. FIG. 9 is a graph showing a result of measuring characteristics using the evaluation system of FIG. 8, and is a frequency characteristic diagram of a coupling level.

Explanation of reference numerals

1 Active device (LSI)
1a Lead wire (pin)
2 EMI countermeasure parts 2 'Composite magnetic body 2a Notch (exposed part)
2b Take-out window 3 Soft magnetic powder having oxide film on surface 4 Organic binder 5 Oscillator for electromagnetic wave source 6 Electromagnetic field strength measuring instrument 7 Micro loop antenna for transmitting electromagnetic field 8 Micro loop antenna for receiving electromagnetic field 9 Sample

Claims (10)

  An EMI countermeasure component for suppressing inductive noise radiated from an active element such as a semiconductor element, wherein the EMI countermeasure component is made of a composite magnetic material containing a soft magnetic material powder having an oxide film on its surface and an organic binder. An EMI countermeasure component characterized in that:   The EMI countermeasure component according to claim 1, wherein the soft magnetic material powder having an oxide film on the surface has a flat shape and / or a needle shape.   The EMI countermeasure component according to claim 2, wherein the flat or / and needle-shaped soft magnetic material powder is oriented and arranged in the composite magnetic material.   The EMI suppression component according to any one of claims 1 to 3, wherein an exposed portion for exposing a part of the surface of the active element is formed to radiate heat from the active element.   An active element having an EMI suppression component, wherein one of the EMI suppression parts according to claim 1 is arranged on an upper surface of an active element such as a semiconductor.   5. An active element having an EMI suppression component, wherein one of the EMI suppression parts according to claim 1 is arranged on a side surface of an active element such as a semiconductor.   An active element having an EMI suppression component, wherein one of the EMI suppression parts according to claim 1 is arranged on a bottom surface of an active element such as a semiconductor.   6. An active element comprising the EMI suppression component according to claim 5, wherein the EMI suppression component surrounds a lead wire connecting the active element and a wiring on a substrate on which the active element is mounted. An active element provided with an EMI suppression component, wherein the EMI suppression component is arranged from an upper surface to a side surface of the element.   7. An active element comprising the EMI suppression component according to claim 6, wherein the EMI suppression component is arranged so as to surround a lead wire connecting the active element and a wiring on a substrate on which the active element is mounted. An active element provided with a EMI countermeasure component. 5. An EMI countermeasure method characterized by suppressing inductive noise radiated from an active element such as a semiconductor element by using any one of the EMI countermeasure components according to claim 1.

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