JP2001035711A - Synthetic resin substrate for wave absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve radio wave absorbing characteristics of a wave absorber by constituting a synthetic resin substrate, having a thickness that falls within the specific range of a composite material of magnetic powder and a synthetic resin, and forming dividing grooves into the substrate to depths, which have specific ratios as depth with respect to the thickness of the substrate. SOLUTION: A synthetic resin substrate 10 for wave absorber has orthogonal primary dividing grooves 11 and secondary dividing grooves 12 on its surface, and a thickness T of the substrate 10 is adjusted to be 0.1-3.0 mm. The depths of the primary grooves 11 are adjusted to 30-70% of the thickness T of the substrate 10. The grooves 11 and 12 are formed by pressing a slitting blade against the substrate 10. The depths D1 and angles θ1 of the primary grooves 11 are made greater than the depths D2 and angles θ2 of the secondary grooves 12. Since the first parted primary dividing grooves 11 are made deeper than the secondary dividing grooves 12, the cracking of the second grooves 12 is prevented at dividing of the grooves 11. In addition, since the angles θ1 on the groove 11 side are made greater than those θ2 on the secondary groove 11 side, sticking of the substrate 10 to the slitting blade can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio wave absorber to be mounted on an electronic device to be miniaturized, and has a substrate shape that can be attached to a housing of the electronic device and has a predetermined size by having a dividing groove. The present invention relates to a synthetic resin substrate that can be divided into chips, printed with a conductor such as a metal, divided into chips, and mounted in a circuit.

[0002]

2. Description of the Related Art In recent years, with the advancement of functions and digital circuits in personal computers and portable telephones, radiated electromagnetic noise generated by circuits has an effect on high-frequency circuits, thereby deteriorating terminal sensitivity. ing. In addition, with the demand for higher functionality, by installing a high-speed microprocessor,
There is a possibility that radiated electromagnetic noise with a frequency close to the operating frequency of high-frequency circuits may be generated from circuits around the microprocessor. To counter these EMI measures, an electromagnetic wave absorbing sheet made of rubber mixed with a magnetic material is used. Was attached to the housing or ferrite beads were used.

[0003]

However, when an electromagnetic wave absorbing sheet in which a magnetic material is mixed with rubber is adhered to a housing, the electromagnetic wave absorbing sheet in which a magnetic material is mixed with rubber has a problem. The mixing ratio of the magnetic material is 3 to
As low as about 70% by volume (see the back of Japanese Patent Application Laid-Open No. 4-213803), when the thickness of the sheet is reduced, the absorptivity of electromagnetic waves is reduced.

Further, in such an electromagnetic wave absorbing sheet, a dividing groove for dividing the sheet into a predetermined shape may be provided. However, since the rubber is used as a base material, the dividing groove is 95% or more of the sheet thickness. You can't divide unless you put it deeply.
However, since the dividing groove is too deep, there is a problem that the handleability is poor and the liquid crystal is divided into single pieces while being carried. Therefore, an adhesive tape is attached to the back surface of the sheet to prevent division during handling. However, when dividing into a predetermined size, there is a problem that the adhesive tape must be cut.

[0005] Further, when a radio wave absorber in which a magnetic material is mixed with a synthetic resin is manufactured in a planar shape, it is individually molded in a tile shape or cut out from a rod-shaped molded body. It was very time-consuming.

Further, in the case of using ferrite beads or the like, and in the case of a portable telephone terminal or the like where the demand for reduction in size and weight is severe,
It is difficult to insert extra components such as ferrite beads into a designed circuit, and components such as ferrite beads are also being miniaturized. For example, the size of ferrite beads is 1.
6 x 0.8 x 0.8 mm, and 1.0 x 0.5 x 0.
It is extremely small at 5 mm, making it extremely difficult to manufacture. In addition, the effect of ferrite material is attenuated at high frequencies. There was a problem that the absorption effect could not be obtained.

On the other hand, when a synthetic resin substrate provided with a dividing groove is divided, if the dividing groove is not appropriate in depth and shape, it cannot be divided along the dividing groove, cracks may occur in the middle of the unit, Burrs were generated on the end face of the substrate later.

Further, when a metal conductor or the like is printed on a synthetic resin substrate, there is a problem that the conductor paste flows into the dividing groove, and the dividing property is deteriorated depending on the angle of the dividing groove.

[0009]

According to the present invention, by using a synthetic resin substrate made of a composite material containing 70 to 99% by weight of magnetic powder dispersed therein, the thickness of the radio wave absorber can be reduced to 0.1 to 100%. Since it can be freely designed in accordance with the frequency of the electromagnetic wave to be absorbed as 3.0 mm, it is suitably used as a radio wave absorber to be attached to a housing or the like, and defines the depth of the dividing groove and its angle with respect to the thickness of the substrate. By doing so, even if it is a very small size, after printing the metal conductor, the occurrence of burrs and the like when dividing into a predetermined shape, the occurrence rate of cracks in the middle of a single body, etc. are reduced, and it is possible to divide appropriately. As a result, a synthetic resin substrate for a radio wave absorber that can be suitably used as a component to be mounted on a circuit requiring strict downsizing is obtained.

That is, the thickness of the synthetic resin substrate is set to 0.1 to 3.
By setting it to 0 mm, the amount of radio wave absorption can be adjusted, and by having a dividing groove having a depth of 30 to 70% of this thickness, the occurrence of burrs, cracks, and the like can be reduced. The reason why the thickness of the substrate is set to 0.1 mm or more is that if the thickness is less than 0.1 mm, the strength of the substrate is reduced and the substrate is easily broken during handling. If the thickness is 3.0 mm or more, the shape becomes too large, and the demand for reduction in size and weight cannot be met. The reason why the depth of the dividing groove is set to 30% or more with respect to the thickness of the substrate is that if it is less than 30%, the dividing property is deteriorated and burrs and cracks are easily generated. Also, if the depth of the dividing groove is 70% or more with respect to the substrate thickness, cracks and cracks are generated along the dividing groove during handling, and the handling property is deteriorated.

[0011] Furthermore, by having vertical and horizontal primary division grooves and secondary division grooves, the depth and angle of the primary division grooves are made deeper than the secondary division grooves, thereby preventing the substrate from sticking to the mold during molding. As a result, cracks and cracks that occur during molding can be prevented.

It is preferable that the difference between the depth of the primary dividing groove and the depth of the secondary dividing groove is in the range of 0.03 to 0.1 mm.

Further, the angle of the primary dividing groove is 30 to 6
0 °, the angle of the secondary division groove is characterized by 25 ~ 40 °, the difference between the angle of the primary division groove and the secondary division groove is 5 ~
Preferably, it is in the range of 25 °. Here, the reason why the angle of the secondary division groove is set to 25 ° or more is that,
This is because, because a fracture line is generated downward from the cutting edge of the slit blade that forms the dividing groove during molding, cracks occur, and stable dividing properties cannot be obtained, and the angle of the primary dividing groove is 30 ° or more. The reason for this is that if it is less than this, if the secondary division groove is 25 °, the angle difference is too small, so that the substrate sticks to the slit blade forming the division groove during molding and cannot be released. Further, when the angle of the primary dividing groove is set to 60 ° or less, since the width of the dividing groove becomes too large, the compressive stress on the substrate becomes large when the thickness of the substrate becomes thin, and the angle of the primary dividing groove becomes large. This is because a difference in density is generated, so that cracks easily occur and cracks easily occur during handling.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

The synthetic resin substrate 10 shown in FIG. 1 has a primary division groove 11 and a secondary division groove 12 which are orthogonal to each other on the surface. The thickness of the synthetic resin substrate 10 is 0.1 to 3.0 mm.
And the depth D of the primary (secondary) division groove is set to the thickness T.
30 to 70%. For this reason, burrs and cracks are less likely to occur, and it can be divided into a predetermined shape with high dimensional accuracy.
Therefore, it can be mounted on an IC such as a CPU, or between other ICs, inside a metal housing or a lid, or on a cable such as an interface between a liquid crystal display of a notebook computer and a keyboard, and the like. As in a mobile phone terminal, a synthetic resin substrate for a radio wave absorber can be obtained which can be mounted in various sizes suitable for the shape of a circuit or a housing or the like, which has a very high density and is required to be miniaturized.

Here, the depth of the dividing groove is determined by adjusting the depth of the synthetic resin substrate 10.
30% to 70% of the depth of the thickness is 30%
This is because burrs are generated on the single body when the synthetic resin substrate 10 is divided. Further, the reason why the ratio is set to 70% or less is that above this, when the thickness of the substrate is reduced to 0.1 mm, the mechanical strength of the substrate is reduced, and when printing conductors on the upper surface of the substrate, the substrate is damaged by printing pressure, This is because handling properties deteriorate during the transportation. still. The difference between the depth D1 of the primary division groove 11 and the depth D2 of the secondary division groove 12 is 0.03 to
It is desirable to set the range to 0.1 mm.

Further, the synthetic resin substrate 10 of the present invention is shown in FIG.
As shown in (a) and (b), the primary blade 11 and the secondary groove 12 were formed by pressing a slit blade. At this time, the depth D1 and the angle θ1 of the primary division groove 11 are larger than the depth D2 and the angle θ2 of the secondary division groove 12, respectively.

This is to prevent the primary divisional groove 11 to be divided first from being broken by the secondary divisional groove 12 at the time of division by the primary divisional groove 11 by making it deeper. In addition, by increasing the angle θ1 on the side of the primary division groove 11, it is possible to prevent sticking to the slit blade during division groove formation processing.

That is, as shown in FIG. 2 (c), when the blade 19 is pressed against the green sheet 10 'to form a dividing groove, the stress F is transmitted in the lateral direction as the cutting edge angle .theta. The synthetic resin substrate 10 ′ is pressed against the blade 19,
Sticking to the slit blade is likely to occur. Therefore, as the cutting edge angle θ is increased, the sticking of the synthetic resin substrate 10 ′ can be prevented.

In the above embodiment, the synthetic resin substrate 1
Although the example in which the dividing grooves are formed on one surface side of No. 0 is shown, these dividing grooves can be formed on both surfaces. In this case, the sum of the depths on both sides is defined as the depth D of the dividing groove, and this depth D may be set in the range of 30 to 70% of the thickness T of the synthetic resin substrate 10.

As shown in FIG. 3, the electromagnetic wave absorber of the present invention is a synthetic resin substrate made of a composite material in which 70 to 99% by weight of magnetic powder 41 is substantially uniformly dispersed and contained in a synthetic resin 40. By using, the thickness of the radio wave absorber is 0.1 to
Since it can be freely designed in accordance with the frequency of the electromagnetic wave to be absorbed as 3.0 mm, it is suitably used as a radio wave absorber to be attached to a housing or the like, and the depth and angle of the dividing groove with respect to the thickness of the substrate. By defining, even if it is a very small size, after the metal conductor is printed, the occurrence of burrs and the like when dividing into a predetermined shape and the incidence of cracks in the middle of a single unit are reduced, and the division is performed appropriately. As a result, the present invention is characterized in that a synthetic resin substrate for a radio wave absorber that can be suitably used as a component to be mounted on a circuit that requires strict miniaturization is characterized.

Here, the magnetic powder 41 is included for adjusting the amount of radio wave absorption of the radio wave absorber, and the radio wave absorption amount of the radio wave absorber can be increased by increasing the content.

However, the reason why the blending amount of the magnetic powder 41 is set to 70 to 99% by weight is that if the blending amount of the magnetic powder is less than 70% by weight, the thickness of the synthetic resin substrate is required to be sufficient to absorb radio waves. Must be made thicker, which cannot contribute to downsizing, and even if a dividing groove is provided, good dividing property cannot be obtained.
Since it is necessary to mold it alone, the cost increases. Conversely, if the blending amount of the magnetic powder is more than 99% by weight, it is difficult to secure the electrical independence of the magnetic powder, and the electrical resistivity of the absorber decreases, so that it does not function as a radio wave absorber.

Here, synthetic resins constituting such a radio wave absorber include epoxy resin, phenol resin, melamine resin, urea resin, unsaturated polyester resin, polyimide resin, furan resin, polybutadiene resin, ionomer resin, and EEA resin. Resin, AAS resin (ASA resin), AS resin, ACS resin, ethylene vinyl acetate copolymer, ethylene vinyl alcohol copolymer resin, ABS resin, vinyl chloride resin,
Chlorinated polyethylene resin, cellulose acetate resin, fluorine resin, polyacetal resin, polyamide resin 6,66, polyamide resin 11,12, polyarylate resin, thermoplastic polyurethane elastomer, liquid crystal polymer, polyetheretherketone, polysulfone resin, polyether Resins such as sulfone resins can be used, and among these, phenol resins are preferred from the viewpoints of heat resistance, dimensional stability, strength and the like.

On the other hand, as the magnetic powder, high permeability amorphous magnetic metal alloys such as Fe-B-Si, Fe-B-Si-C
System, Fe-B-Si-Cr system, Fe-Co-B-Si system, Fe-Ni-Mo-B system, Co-F
Magnetic metal alloys such as e-Ni-Mo-B-Si, Co-Fe-Ni-B-Si
Ni-Fe alloys such as 36-permalloy, 45-permalloy,
μ-metal, 78-permalloy, Cr-permalloy, Supermalloy
Magnetic metal alloys such as pure iron, mild steel, Fe-Si alloy, Fe-Al alloy, Fe-Si-Al alloy, Co-Fe alloy, Mn-Zn ferrite, Ni-Zn ferrite, Cu-Zn Ferrite, Cu-Zn-
Mg ferrite, Mn-Mg-Al ferrite, Ba ferrite, ferromagnetic sprayer, etc. can be used, but high permeability amorphous magnetic metal alloys and Ni-Fe alloys (permalloy) are particularly preferably used.

It is known that the shape of the magnetic powder has an important effect on the magnetic loss and the like of the radio wave absorber.
Flakes, plates, flats, needles, and fibers having a large aspect ratio are preferably used. In addition, the magnetic powder, even in the high filling state, to ensure insulation,
Desirably, at least the surface is oxidized or the individual particles are completely electrically isolated by the synthetic resin.

The above-mentioned synthetic resin and magnetic powder are mixed in the above-mentioned weight ratio, and the obtained raw materials are mixed with each other by a conventionally known molding method such as a doctor blade method, a rolling method, a hot press molding method, a cast molding method. By pressing a slit blade against a synthetic resin substrate formed into a substrate shape by a powder pressing method or the like to form a dividing groove, a synthetic resin substrate for a radio wave absorber that can be divided into arbitrary shapes with high dimensional accuracy is obtained.

[0028]

Embodiment 1 Hereinafter, the present invention will be described more specifically with reference to embodiments. However, the present invention is not limited to the following examples unless it exceeds the gist.

An electromagnetic wave absorber having a different blending amount of magnetic powder was manufactured, and an experiment was conducted for examining the absorption characteristics with respect to radio waves of 1 GHz to 20 GHz.

In this experiment, a resol type phenol resin was used as the thermosetting resin forming the composite material, and permalloy was used as the magnetic powder. After mixing the phenolic resin and permalloy at various mixing ratios, changing the thickness, forming into a substrate, pressing a slit blade to form a dividing groove,
It was cured by heating at 80 ° C to 250 ° C to prepare a test piece.

As shown in Table 1, various ratios of the depth D and the thickness T of the dividing groove were prepared, and the dividing property of each substrate was evaluated. Cracks, burrs, cracks and burrs on the single unit after splitting, cracks in the middle of the single unit, etc. were found.No cracks were found during handling.を for those that did not have
Indicated by

As a result, if the thickness was less than 0.1 mm, the substrate cracked during handling and the strength of the substrate itself was low, so that many single cracks occurred. On the other hand, if the thickness exceeds 3.0 mm, the division cannot be performed unless the depth of the dividing groove with respect to the substrate is increased, and burrs are generated on the substrate alone. Therefore, it is understood that the thickness of the substrate is preferably 0.1 to 3.0 mm. Further, in this range, the ratio D / D of the division groove depth D to the substrate thickness T
When T (%) is 30 to 70%, the splitting property is good, no burrs are generated on the single piece, no crack is generated in the middle of the single piece, and a single piece with good dimensional accuracy can be obtained with good yield.

[0033]

[Table 1]

Example 2 Next, in the synthetic resin substrate manufactured in the same manner as in Example 1, the depth D1 of the primary division groove was set to 60% of the thickness T, and the depth D2 of the secondary division groove was set to 50% of the thickness T. Then, one in which the angle θ1 of the primary division groove was variously changed was prepared. In each case, the angle θ2 of the secondary division groove was smaller than θ1.

When forming the dividing grooves in the respective synthetic resin substrates, the releasability from the slit blade was evaluated. Next, the splitting property was evaluated, and the presence or absence of the obtained single crack was examined. Regarding the adhesion to the slit blade, those where the synthetic resin substrate does not adhere to the blade are indicated by ○ and those which adhere to the slit blade are indicated by x. Regarding the dividability, those that were correctly broken along the dividing grooves are indicated by ○, and those that were not broken are indicated by x. In the inspection of cracks, even if one out of 1,000 single cracks, a crack is indicated by x, and a crack is not indicated by ○.

As shown in Table 2, the angle θ1 of the primary dividing groove is set to 3
It can be seen that if the angle is set to 0 to 60 °, there is no adhesion to the blade, the dividing property is good, and the occurrence of cracks can be prevented.

[0037]

[Table 2]

Example 3 Next, as in Example 2, various secondary grooves having different angles θ2 were manufactured, and the presence / absence of adhesion, division property, and cracks were confirmed. In each case, the angle of the primary dividing groove was set to 50 °.

As shown in Table 3, the angle θ2 of the secondary dividing groove is set to 2
It is understood that if the angle is set to 5 to 45 °, there is no adhesion to the blade, the dividing property is good, and the occurrence of cracks can be prevented.

[0040]

[Table 3]

Embodiment 4 Next, the amount of radio wave absorption was measured using a waveguide and a coaxial tube.
The test piece was short-circuited on one side with a metal, and a radio wave of 0.1 GHz to 12 GHz was incident on the other side. Table 4 shows the results.

According to Table 4, when Permalloy is less than 70% by weight, the radio wave absorption characteristics are poor, while those within the range of the present invention (No. 6 to No. 10) have a radio wave absorption of 20 dB or more. Properties could be given.

[0043]

[Table 4]

[0044]

According to the present invention, a composite material of 70 to 99% by weight of a magnetic powder and a synthetic resin has a thickness of 0.1 to 100%.
A radio wave absorber having excellent radio wave absorption characteristics can be obtained by using a synthetic resin substrate for a radio wave absorber having a dividing groove having a depth of 3.0 mm and a depth of 30 to 70% of this thickness. Can be used for various applications.

[Brief description of the drawings]

FIG. 1A is a perspective view showing a synthetic resin substrate of the present invention, and FIG. 1B is a cross-sectional view.

2A is a cross-sectional view along a primary division groove of the synthetic resin substrate of the present invention, FIG. 2B is a cross-sectional view perpendicular to the primary division groove,
(C) is sectional drawing which shows the processing method of a division groove | channel.

FIG. 3 is a diagram schematically showing a cross section of a radio wave absorber of the present invention.

[Explanation of symbols]

 10: Synthetic resin substrate 11: Primary division groove 12: Secondary division groove 19: Slit blade 40: Synthetic resin 41: Magnetic powder

Claims (5)

[Claims] 1. A synthetic resin substrate containing magnetic powder, having a thickness of 0.1 to 3.0 mm, and having a dividing groove having a depth of 30 to 70% of the thickness. Synthetic resin substrate for radio wave absorbers. 2. The method according to claim 1, wherein the dividing groove has a primary dividing groove to be divided first and a secondary dividing groove to be divided later, and a depth and an angle of the primary dividing groove are respectively made larger than those of the secondary dividing groove. The synthetic resin substrate for a radio wave absorber according to claim 1. 3. The synthetic resin substrate for a radio wave absorber according to claim 3, wherein the angle of the primary division groove is 30 to 60 ° and the angle of the secondary division groove is 25 to 40 °. 4. The synthetic resin substrate for a radio wave absorber according to claim 1, wherein a conductor such as a metal is printed on said substrate. 5. The synthetic resin substrate for a radio wave absorber according to claim 1, wherein the magnetic powder contains 70 to 99% by weight of the dispersion.