JP2008198697A - Method for grounding electromagnetic wave shielding member formed of conductive resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To save the time required for grounding work of an electromagnetic wave shielding member in the method for grounding the electromagnetic wave shielding member formed of a conductive resin. <P>SOLUTION: An element 20 constituting a housing element as the electromagnetic wave shielding member is molded into a shape including a V-shaped channel 24 having the V-shaped cross-section on a single surface in the thickness direction with the conductive resin. Thereafter, the housing element is formed where a conductive part is exposed to a mark of crack or to a cracking part by cracking the element 20 at the V-shaped channel part 24. Thereafter, a grounding wire is connected directly or via the other conductor to the conductive part exposed in both sides of the mark of crack or cracking part of the housing element. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electromagnetic wave shield made of a conductive resin, in which a material constituting an electromagnetic wave shield member is molded from a conductive resin, and the ground wire is connected to a conductive portion directly or via another conductor in the electromagnetic wave shield member. The present invention relates to a method for grounding a member.

  Conventionally, as a measure for suppressing the influence of electromagnetic waves such as electromagnetic noise from the outside of an electric circuit part such as a printed circuit board in which electric elements are electrically connected, an electric circuit part (not shown) is provided as shown in FIG. It is conceivable that the casing 10 is disposed inside the casing 10 made of a conductive material having conductivity, and the casing 10 is grounded (grounded). With such a case 10, there is a possibility that an electromagnetic wave shielding effect can be obtained in which the case 10 has substantially the same potential as the ground 12 and the electric circuit portion is hardly affected by electromagnetic waves from the outside. On the other hand, when the casing 10 is not grounded, the voltage of the casing 10 rises, causing the casing 10 itself to generate an electromagnetic wave, and the electric circuit unit disposed inside the casing 10 is caused by the electromagnetic wave. May be adversely affected. For this reason, grounding the casing 10 made of a conductive material is preferable from the viewpoint of making it less susceptible to electromagnetic waves in the electric circuit portion.

  In order to configure the case 10 made of such a conductive material, it is considered that the case element constituting the case 10 is constituted by a member made of conductive resin called an “electromagnetic wave shielding member”. . In the entire specification and claims, the term “electromagnetic wave shielding member” means that a filler called conductive filler (copper, carbon, etc.) serving as a shielding material is mixed in a resin serving as a base material. The member which comprises by doing.

  However, when the casing element is made of a conductive resin, when the casing element is molded, a resin having a higher fluidity than the conductive filler (filler) flows into the surface of the casing element, and the skin Insulating portions called layers are easily formed on the surface of the housing element. When the insulating portion is formed on the surface of the housing element as described above, the effect of grounding the housing element cannot be sufficiently obtained even if the ground wire is directly connected to the surface of the housing element. In order to ground such a housing element, for example, by cutting the surface of the housing element or the like, the insulating portion of the surface is pierced and the conductive portion exposed on the surface is exposed. It is necessary to perform work such as connecting a conductor such as a ground wire.

  For example, conventionally, as shown in FIG. 10, the casing element 14 is made of an electromagnetic shielding member made of conductive resin, and the casing element 14 and a metal object 16 such as a metal fitting are connected by a bolt 18. Is considered. Then, one end of a ground wire (not shown) is connected to the metal object 16 or the bolt 18 and the other end of the ground wire is grounded to ground the housing element 14. In the case of the configuration shown in FIG. 10, processing is performed to form the hole 19 for breaking through the insulating portion formed on the surface when the housing element 14 is molded, and the bolt 18 is inserted into the hole 19. By screw coupling to the metal fitting 16, the conductive portion of the housing element 14 and the metal bolt 18 can be electrically connected. If the casing is configured by such a casing element 14, an electromagnetic wave shielding effect can be obtained in which the electric circuit unit installed in the casing is less susceptible to electromagnetic waves.

  Patent Document 1 describes a housing structure of an electronic device in which metal top plates and bottom plates that are housing elements are grounded. In the case of the housing structure of the electronic device described in Patent Document 1, the top plate is grounded through the grounding metal by rubbing the grounding metal against the insulating coating formed on the back surface of the metal top. Yes. Further, the bottom plate is also grounded by breaking through the insulating coating on the back surface of the top plate by a pointed projection provided at the periphery of the screw hole formed in the bottom plate.

Japanese Patent No. 2834934

  In the case of the structure shown in FIG. 10, it is necessary to perform a processing operation for forming a hole portion 19 for inserting the bolt 18 into the casing element 14 in order to ground the casing element 14 made of conductive resin. is there. Further, when such a hole 19 is not formed, it is necessary to perform a processing operation such as cutting the surface of the housing element 14 with a processing tool to break through the insulating portion on the surface of the housing element 14. However, it is necessary for the grounding work of the housing element 14 that is an electromagnetic wave shielding member to form the hole 19 or to perform the machining work such as the shaving process to break through the insulating portion on the surface of the housing element 14 in this way. Causes longer time.

  In the case of the casing structure of the electronic device described in Patent Document 1, the casing elements are a metal top plate and a bottom plate, and do not disclose a method of grounding an electromagnetic shielding member made of conductive resin. .

  An object of the present invention is to shorten the time required for the grounding work of the electromagnetic wave shielding member in the grounding method of the electromagnetic wave shielding member made of conductive resin.

  In the method for grounding an electromagnetic wave shielding member made of conductive resin according to the present invention, after forming the material constituting the electromagnetic wave shielding member into a shape having a concave portion or a step portion on the side surface by the conductive resin, the material is formed into the concave portion or step. An electromagnetic shielding member in which a conductive portion is exposed at a crack mark or a crack is formed by dividing by a portion, and the conductive portion exposed on both sides of the crack mark or the crack is grounded in the electromagnetic shielding member. A method for grounding an electromagnetic wave shielding member made of a conductive resin, characterized in that a wire is connected directly or via another conductor.

  Preferably, the recess or step provided in the material constituting the electromagnetic wave shielding member is a V-shaped groove provided in a straight line with a V-shaped cross section on the side surface of the material.

  Preferably, the recesses or stepped portions provided in the material constituting the electromagnetic wave shielding member are a plurality of recesses provided intermittently on a virtual straight line on the side surface of the material.

  Preferably, the concave portion or the step portion provided in the material constituting the electromagnetic wave shielding member is formed as two straight concave grooves provided in a state of being opposed to each other with a thin portion sandwiched between both surfaces of the material.

  Preferably, the material constituting the electromagnetic wave shielding member is plate-shaped, and the recess or step provided in the material is a linear hole penetrating in the length direction or width direction of the material.

  According to the grounding method of the electromagnetic shielding member made of conductive resin according to the present invention, in order to connect the ground wire to the electromagnetic shielding member, the conductive resin material is divided by the concave portion or the step portion, and cracks or cracks are formed. The ground wire may be connected to the conductive portions exposed on both sides of the wire directly or via other conductors, and the work of dividing the material by the concave portion or the step portion can be easily performed in a short time. That is, since the concave portion or the step portion is provided in the material, the material is easily broken at the concave portion or the step portion. For this reason, the operation | work which exposes the part which has electroconductivity to a raw material can be performed easily in a short time. Moreover, in order to break through the insulating portion of the surface of the electromagnetic wave shielding member made of conductive resin and connect the conductor, a hole for inserting a bolt into the electromagnetic wave shielding member is formed, or the surface of the electromagnetic wave shielding member is formed with a processing tool. It is not necessary to perform a long working process such as cutting. As a result, the time required for the grounding work of the electromagnetic wave shielding member can be shortened.

[First Embodiment]
Hereinafter, embodiments according to the present invention will be described in detail with reference to the drawings. 1 to 2 show a first embodiment. FIG. 1 is a partial perspective view showing a material 20 constituting a plate-shaped casing element which is an electromagnetic wave shielding member, which is grounded by a grounding method of an electromagnetic wave shielding member made of a conductive resin according to the present embodiment. 2A is a partial perspective view showing a housing element 22 formed by completely dividing the material 20 of FIG. 1, and FIG. 2B is a view of leaving the material 20 of FIG. It is a fragmentary perspective view which shows another example of the housing element 22a comprised by dividing by. The casing elements 22 and 22a are used as, for example, a top plate, a bottom plate, a horizontal plate, and the like constituting the casing 10 (see FIG. 9) of an automobile electronic device (not shown). The casing elements 22 and 22a are made of conductive resin that is conductive resin.

  Such a grounding method for grounding the casing elements 22 and 22a made of conductive resin, that is, grounding the casing elements 22 and 22a, is performed as follows. First, as shown in FIG. 1, the material 20 constituting the casing elements 22 and 22a (FIGS. 2A and 2B) is formed into a concave portion on one side in the thickness direction (upper side surface in FIG. 1) by a conductive resin. Yes, it is formed into a plate shape having a V-shaped groove 24, which is a linear slit having a V-shaped cross section. The conductive resin is configured by mixing a filler (copper, carbon, or the like) called a conductive filler serving as a shielding material into a resin serving as a base material. At the time of molding such a material 20, a resin having high fluidity flows into a portion that becomes the surface of the material 20 inside the mold, and the filling material having low fluidity conductivity is removed from the surface of the material 20. To make up part. For this reason, the surface of the molded material 20 is covered with an insulating portion. For this reason, the grounding effect cannot be obtained even if the ground wire is connected to the surface of the material 20 as it is.

  The present embodiment has been made in consideration of such circumstances, and as shown in FIG. 1, the material 20 has a thickness direction on one side (the upper side in FIG. 1) and a width direction (the front and back directions in FIG. 1). Are formed into a plate shape having V-shaped grooves 24 extending linearly. Both ends of the V-shaped groove 24 reach both side surfaces of the material 20 in the width direction.

  Next, as shown in FIG. 2A, the both sides of the length direction of the material 20 (left and right direction in FIG. 1) are bent in the same direction (downward direction in FIG. 1) in the direction indicated by the arrow A in FIG. In addition, the material 20 is divided by the V-shaped groove 24 portion, and thereby, the housing element 22 is configured by the one side portion (left side portion in FIG. 1) that is broken. Further, in this state, a conductive portion is exposed at the crack 25 of the housing element 22 (the portion indicated by the matte surface in FIG. 2A). Then, one end of the ground wire 26 is directly connected to the conductive portion exposed at the crack 25 of the housing element 22 and the other end (not shown) of the ground wire 26 is grounded (grounded). For example, in the case where a casing constituted by the casing element 22 is mounted on an automobile, the other end of the ground wire 26 is connected to the vehicle body. The housing element 22 and the ground wire 26 are connected by various methods such as soldering. It is also possible to connect the ground wire 26 to the crack 25 of the housing element 22 via another conductor such as a connector and a conductor without connecting the ground wire 26 directly to the housing element 22. The V-shaped groove 24 is formed so as to extend linearly in the length direction (left-right direction in FIG. 1) on one side in the thickness direction of the material 20, and the material 20 is divided by the V-shaped groove 24 portion. A housing element can also be configured.

  Further, as in another example shown in FIG. 2B, the material 20 (FIG. 1) is divided halfway at the V-shaped groove 24 portion, that is, the bottom of the V-shaped groove 24, and the both side portions sandwiching the V-shaped groove 24. In a state where the two are partially coupled, the casing element 22a (FIG. 2B) is configured by exposing the conductive portions on both sides of the crack 28 formed at the bottom of the V-shaped groove 24. You can also. In this case, in the housing element 22a, the ground wire 26 and the material 20 are connected in a state where one end of the ground wire 26 is sandwiched between conductive portions exposed on both sides of the crack 28, and the housing element 22a. The ground wire 26 is connected to the conductive part. It is also possible to connect the housing element 22a and the ground wire 26 via other conductors so that the other conductors connected to the ground wire 26 are sandwiched between both side portions of the crack 28 of the housing element 22a. .

  According to the grounding method of the electromagnetic shielding member made of conductive resin according to this embodiment, the conductive resin material 20 (FIG. 1) is used to connect the ground wire 26 to the casing elements 22 and 22a. Is divided by the V-shaped groove 24 portion, and the ground wire 26 may be connected to the conductive portions exposed on both sides of the crack mark 25 or the crack 28 directly or via other conductors. The division work can be easily performed in a short time. That is, since the V-shaped groove 24 is provided in the material 20, the material 20 is easily broken at the V-shaped groove 24 portion. For this reason, the operation | work which exposes the part which has electroconductivity to the raw material 20 can be performed easily in a short time.

  Further, in order to break through the insulating portion of the surface of the casing elements 22 and 22a (FIGS. 2A and 2B) made of conductive resin and connect a conductor such as the ground wire 26, bolts are connected to the casing elements 22 and 22a. There is no need to perform a long working process such as forming a hole for inserting the surface of the casing element 22 or 22a with a machining tool. As a result, the time required for the grounding work of the casing elements 22 and 22a can be shortened. Further, if the casing 10 (see FIG. 9) is configured by the casing elements 22 and 22a obtained by the present embodiment, the potential of the casing 10 is substantially the same as that of the ground 12 as shown in FIG. Therefore, it is difficult for electromagnetic waves to enter the inside of the housing 10. For this reason, if an electric circuit unit such as a printed circuit board is arranged inside the housing 10, the electric circuit unit can be hardly affected by external electromagnetic waves.

  Further, as in another example shown in FIG. 2B, the ground wire 26 is connected to the housing element 22a with the ground wire 26 or another conductor connected to the ground wire sandwiched between both sides of the crack 28. In this case, the work of connecting the ground wire 26 to the housing element 22a is made easier, and the work of grounding the housing element 22a is made easier.

[Second Embodiment]
3 to 4 show a second embodiment of the present invention. FIG. 3 is a partial perspective view of the material 20a corresponding to FIG. 1 in the present embodiment, and FIG. 4 is a portion of the housing element 22b corresponding to FIG. 2A in the present embodiment. It is a perspective view. In the case of the material 20a shown in FIG. 3 constituting the housing element 22b, a through-hole 30 having a circular or oval cross section, which is a plurality of recesses, on an imaginary straight line on one side (upper side surface of FIG. 3) of the material 20a. Are provided intermittently. The plurality of through holes 30 penetrate both side surfaces of the material 20 in the thickness direction (vertical direction in FIG. 3). As a result, a plurality of through holes 30 are formed in the material 20 in a perforated shape.

  In the case of the present embodiment, such a material 20a is used, and both sides of the material 20a in the length direction (left and right direction in FIG. 3) are directed in the same direction (downward direction in FIG. 3) in the direction of arrow A in FIG. By bending and dividing the material 20 by a plurality of through-hole 30 portions, as shown in FIG. 4, the housing element 22b is constituted by one side portion that is broken. Then, the ground wire 26 (see FIG. 2A) is directly or directly attached to the crack 25 of the housing element 22b (the portion indicated by the satin surface in FIG. 4) in the same manner as shown in FIG. The connection is made through another conductor (not shown).

  In the case of this embodiment, the casing element 22b is configured by dividing the material 20 by a plurality of through-holes 30. For this reason, the operation | work which exposes the part which has electroconductivity to the housing | casing element 22b can be easily performed in a short time. Other configurations and operations are the same as those in the first embodiment described above, and a duplicate description is omitted.

[Third Embodiment]
FIG. 5 is a partial perspective view corresponding to FIG. 2A, showing a housing element 22c according to the third embodiment of the present invention. As shown in FIG. 5, the plurality of concave portions provided in the material constituting the housing element 22 c can be concave holes that do not penetrate the other surface in the thickness direction (the lower surface in FIG. 5). Other configurations and operations are the same as those of the second embodiment shown in FIGS.

  In the second embodiment and the third embodiment shown in FIGS. 3 to 5 above, when the casing elements 22b and 22c are configured, the material 20a that configures the casing elements 22b and 22c. (FIG. 3) exposes the conductive parts on both sides of the cracks by splitting them leaving some joints so that the cracks remain in the plurality of through-hole 30 parts or the plurality of recessed hole parts. It is also possible to connect the ground wire directly or through another conductor to the exposed conductive portion.

[Fourth Embodiment]
FIG. 6 is a partial perspective view of the material 20b corresponding to FIG. 1 in the fourth embodiment of the present invention. As shown in FIG. 6, the material 20 b constituting the housing element according to the present embodiment has a V-shaped groove 24 a having a V-shaped cross section, which is a recess, opened on one side in the width direction (the front side in FIG. 6). Forming. That is, in the case of the first embodiment shown in FIG. 1, the V-shaped groove 24 provided in the material 20 has a V-shaped wide opening end on one side in the thickness direction of the material 20 (upper surface in FIG. 1). In this embodiment, the V-shaped groove 24 a provided in the material 20 is formed so that the wide opening end of the V shape opens on one side in the width direction of the material 20. . Further, both ends of the V-shaped groove 24a reach both surfaces of the material 20 in the thickness direction (vertical direction in FIG. 6).

  In the case of this embodiment, the material 20b is bent by bending both sides of the material 20b in the length direction (left-right direction in FIG. 6) in the same direction (back direction in FIG. 6) in the direction of arrow A in FIG. The casing element is formed by dividing the V-shaped groove 24a and exposing the conductive portions on both sides of the crack or the crack. And the ground wire 26 (refer FIG. 2 (a) (b)) is connected to the part which has the electroconductivity exposed to the crack mark of a housing | casing element, or both sides of a crack, directly or via another conductor. Other configurations and operations are the same as those of the first embodiment shown in FIGS.

[Fifth Embodiment]
FIG. 7 is a partial perspective view of the material 20c corresponding to FIG. 1 in the fifth embodiment of the present invention. In the case of the present embodiment, as shown in FIG. 7, each of the materials 20c constituting the housing element has a linear shape with both sides facing each other with the thin portion 32 interposed therebetween in the thickness direction (vertical direction in FIG. 7). Two concave grooves 34 are provided. Both ends of the two concave grooves 34 reach both ends in the width direction of the material 20 (front and back direction in FIG. 7). In the present embodiment, the two concave grooves 34 correspond to the concave portions, respectively.

  In the case of this embodiment, the material 20c is bent by bending both sides of the material 20c in the length direction (left and right direction in FIG. 7) in the same direction (downward direction in FIG. 7) in the direction of arrow A in FIG. The housing element is formed by dividing the two concave groove portions 34 and exposing portions having conductivity on both sides of the crack mark or the crack. And the ground wire 26 (refer FIG. 2 (a) (b)) is connected to the part which has the electroconductivity exposed to the crack mark of a housing | casing element, or both sides of a crack directly or via another conductor. Other configurations and operations are the same as those of the first embodiment shown in FIGS.

[Sixth Embodiment]
FIG. 8 is a partial perspective view of the material 20d corresponding to FIG. 1 in the sixth embodiment of the present invention. In the case of the present embodiment, as shown in FIG. 8, the material 20d constituting the housing element is formed into a plate shape, and the material 20d is penetrated in the width direction (front and back direction in FIG. 8) and has a linear shape and a rectangular cross section. A through hole 36 which is a hole having a shape is provided. Both ends of the through hole 36 reach both ends in the width direction of the material 20d. Thereby, a part of the raw material 20d is formed in a hollow shape. In the present embodiment, the through hole 36 corresponds to the recess.

  In the case of this embodiment, the material 20 is bent by bending both sides of the material 20d in the length direction (left-right direction in FIG. 8) in the same direction (downward in FIG. 8) in the direction of arrow A in FIG. The casing element is formed by dividing the through hole 36 portion and exposing portions having conductivity on both sides of the crack or the crack. And the ground wire 26 (refer FIG. 2 (a) (b)) is connected to the part which has the electroconductivity exposed to the crack mark of a housing | casing element, or both sides of a crack directly or via another conductor. Other configurations and operations are the same as those of the first embodiment shown in FIGS.

  In addition, the through-hole 36 provided in the raw material 20d can also be provided in a state of penetrating in the length direction (left-right direction in FIG. 8) of the raw material 20d. In this case, by bending both sides of the material 20d in the width direction (front and back direction in FIG. 8) in the same direction, the material 20 is divided by the through-hole 36 portion to constitute a casing element.

  In addition, although illustration is abbreviate | omitted, in each said embodiment, the step part which has a level | step difference surface instead of a recessed part can also be formed in the side surface of the raw material which comprises a housing | casing element. When the material is formed into a shape having a stepped portion as described above, a case element is formed by dividing the material by the stepped portion, thereby exposing a cracked trace or a conductive portion in the crack. In the body element, the ground wire can be connected directly or via other conductors to the conductive portions exposed on both sides of the crack or the crack. Even in such a case, since the material easily breaks at the step portion, the work of exposing the conductive portion to the casing element can be easily performed in a short time. For this reason, the time required for the grounding operation of the casing element can be shortened.

It is a fragmentary perspective view which shows the raw material which comprises the housing | casing element which is an electromagnetic wave shielding member grounded with the earthing | grounding method of the electromagnetic shielding member made from the conductive resin which concerns on embodiment of 1st invention. (A) is a fragmentary perspective view which shows the housing | casing element comprised by dividing the raw material of FIG. 1 completely, (b) is another housing element comprised by dividing the raw material of FIG. 1 leaving a crack. It is a fragmentary perspective view which shows an example. In embodiment of 2nd invention, it is the fragmentary perspective view of a raw material corresponding to FIG. FIG. 3 is a partial perspective view of a housing element corresponding to FIG. 2 (a). It is a fragmentary perspective view corresponding to Drawing 2 (a) showing a case element concerning an embodiment of the 3rd invention. In embodiment of 4th invention, it is a fragmentary perspective view of a raw material corresponding to FIG. In embodiment of 5th invention, it is a fragmentary perspective view of a raw material corresponding to FIG. In embodiment of 6th invention, it is a fragmentary perspective view of a raw material corresponding to FIG. FIG. 5 is a schematic diagram showing a state in which a casing made of a conductive material is grounded in order to make it less susceptible to external electromagnetic waves in an electric circuit unit disposed inside the casing. It is a fragmentary sectional view showing one example of the structure for grounding the case element considered conventionally.

Explanation of symbols

  10 housing, 12 ground, 14 housing element, 16 metal object, 18 bolt, 19 hole, 20, 20a, 20b, 20c, 20d material, 22, 22a, 22b, 22c housing element, 24, 24a V-shaped Groove, 25 crack mark, 26 ground wire, 28 crack, 30 through hole, 32 thin part, 34 concave groove, 36 through hole.

Claims (5)

After forming the material constituting the electromagnetic wave shielding member into a shape having a recess or a step on the side surface with a conductive resin,
By dividing the material by the recessed portion or the stepped portion, an electromagnetic shielding member in which the conductive portion is exposed at the crack mark or the crack is constituted,
A grounding method for an electromagnetic shielding member made of a conductive resin, wherein an earth wire is connected directly or via another conductor to a conductive portion exposed on both sides of a crack mark or a crack in an electromagnetic shielding member . In the grounding method of the electromagnetic shielding member made of conductive resin according to claim 1,
A method for grounding an electromagnetic shielding member made of a conductive resin, wherein the concave portion or the step portion provided in the material constituting the electromagnetic shielding member is a V-shaped groove provided in a straight shape with a V-shaped cross section on the side surface of the raw material. In the grounding method of the electromagnetic shielding member made of conductive resin according to claim 1,
A method for grounding an electromagnetic shielding member made of conductive resin, wherein the concave portions or step portions provided in the material constituting the electromagnetic shielding member are a plurality of concave portions provided intermittently on a virtual straight line on a side surface of the raw material. In the grounding method of the electromagnetic shielding member made of conductive resin according to claim 1,
The concave portion or the step portion provided in the material constituting the electromagnetic wave shielding member is made of conductive resin, characterized in that each of the concave portions or the step portion provided on both surfaces of the raw material is opposed to each other with the thin portion sandwiched therebetween. Grounding method for electromagnetic wave shielding member. In the grounding method of the electromagnetic shielding member made of conductive resin according to claim 1,
The material constituting the electromagnetic shielding member is plate-shaped, and the recess or step provided in the material is a linear hole penetrating in the length direction or width direction of the material. Grounding method of electromagnetic shielding member.

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