JP2021170604A - Box type electronic unit - Google Patents

Abstract

To provide a box-type electronic unit that can perform the desired electromagnetic wave shielding function even if relative positions of a resin case and an electromagnetic wave shielding member change due to differences in thermal expansion rates.SOLUTION: A box type electronic unit 1 comprises: an electronic circuit board 30; a resin case 10 that houses the electronic circuit board 30; electromagnetic wave shielding members 50, 60 that are formed separately from the resin case 10 using a material having a different thermal expansion coefficient from the resin case 10, are attached to the resin case 10, and are at least partially exposed; and a viscoelastic shielding layer 90 that is molded from a polymer viscoelastic material having electromagnetic wave shielding properties and is disposed over the resin case 10 and the electromagnetic wave shielding members 50, 60 in a state contacting with the resin case 10 and the electromagnetic wave shielding members 50, 60.SELECTED DRAWING: Figure 5

Description

The present invention relates to a box-type electronic unit.

Patent Document 1 describes a housing shield structure. This housing shield structure includes a case that houses an electronic circuit board and has a shielding function, and a shield cover that covers an opening of the case. The case and shield cover are formed by casting using materials such as aluminum, magnesium and zinc. Further, the housing shield structure includes a packing formed of conductive rubber which is interposed and arranged between the case and the shield cover. That is, the packing has a shielding function and a waterproof function. Therefore, a complete shield structure can be formed in the case.

Patent Document 2 describes that a gasket made of electromagnetic wave shield rubber is arranged between a circuit board and a shield plate. Further, Patent Document 2 describes that the same gasket as described above is arranged between the inner surface of the housing and the shield plate.

Japanese Unexamined Patent Publication No. 2003-069275 Japanese Unexamined Patent Publication No. 2002-185181

In recent years, in box-type electronic units, the use of resin instead of metal for the case has been increasing from the viewpoint of weight reduction and cost reduction. Here, the box-type electronic unit is required to have an electromagnetic wave shielding function with respect to the electronic circuit board. The electromagnetic wave shielding function includes a function of reflecting electromagnetic waves and a function of absorbing electromagnetic waves.

In a portion having an electromagnetic wave shielding function, an electromagnetic wave shielding member formed separately from the resin case by a material having a coefficient of thermal expansion different from that of the resin case may be arranged in the resin case. In such a structure, for example, at the connection portion between the resin case and the peripheral edge of the electromagnetic wave shield member, the relative positions of the two may change due to the difference in the coefficient of thermal expansion. Due to this change in relative position, a gap may be created and the desired electromagnetic wave shielding function may not be exhibited.

The present invention provides a box-shaped electronic unit capable of exhibiting a desired electromagnetic wave shielding function even if the relative positions of the resin case and the electromagnetic wave shielding member change due to the difference in the coefficient of thermal expansion. The purpose.

The box-shaped electronic unit is formed separately from the resin case by the electronic circuit board, the resin case accommodating the electronic circuit board, and the material having a coefficient of thermal expansion different from that of the resin case, and is attached to the resin case. The resin case and the electromagnetic wave shielding member are formed of an electromagnetic wave shielding member that exposes at least a part thereof and a polymer viscoelastic material having an electromagnetic wave shielding property, and are in contact with the resin case and the electromagnetic wave shielding member. It is provided with a viscoelastic shield layer arranged so as to straddle and.

According to the box-shaped electronic unit, a viscoelastic shield layer formed of a polymer viscoelastic material having an electromagnetic wave shielding property is arranged straddling the resin case and the electromagnetic wave shielding member in a state of being in contact with the electromagnetic wave shielding member. ing. Therefore, even if the relative positions of the resin case and the electromagnetic wave shield member change due to the resin case and the electromagnetic wave shield member being molded by materials having different coefficients of thermal expansion, the viscoelastic shield layer changes in the relative position. Can be followed. Therefore, the desired electromagnetic wave shielding function can be exhibited.

It is a perspective view which looked at the appearance of a box type electronic unit from above. It is a perspective view which looked at the appearance of the box type electronic unit from the bottom. It is an exploded perspective view of a box type electronic unit. It is a further exploded perspective view of a part structure in a box type electronic unit. It is an enlarged view of the cross section AA of FIG. It is a flowchart which shows the manufacturing method of a box type electronic unit. It is sectional drawing which shows the product in step S2 of FIG. It is sectional drawing which shows the object in the 2nd type in step S4 of FIG. It is sectional drawing which shows the product in step S5 of FIG. It is sectional drawing which shows the product in steps S6 and S7 of FIG.

(1. Applicable target)
The box-type electronic unit is a unit that houses an electronic circuit board and is required to be drip-proof and waterproof. The box-type electronic unit has a heat dissipation function in order to dissipate the heat of the electronic circuit board housed inside to the outside. Further, the box-type electronic unit has an electromagnetic wave shielding function in order to make the electronic circuit board housed inside less susceptible to electromagnetic wave noise from the outside.

The box-type electronic unit is applied to, for example, an automobile ECU (electronic control unit). The box-type electronic unit is applied to, for example, an engine ECU, a motor ECU, an air conditioner ECU, a camera ECU, a radar ECU, and the like as an automobile ECU.

(2. Appearance of box-type electronic unit 1)
The appearance of an example of the box-type electronic unit 1 will be described with reference to FIGS. 1 and 2. As shown in FIGS. 1 and 2, the box-shaped electronic unit 1 has a flat outer shape due to the resin case 10 and the lid 20. In this example, the outer shape of the box-shaped electronic unit 1 is shown as a rectangular flat shape, but it can be a flat shape having an arbitrary shape such as another polygon or a circle. An electronic circuit board 30 (shown in FIG. 3) is housed inside the resin case 10 and the lid 20. Further, the resin case 10 is provided with a heat dissipation opening 11a1 that penetrates on the back surface. Further, the resin case 10 is provided with a non-penetrating recess 11a2 on the back surface.

The box-type electronic unit 1 further includes a connector 40 that projects outward from a flat outer shape formed by the resin case 10 and the lid 20. The connector 40 is fitted into an external connector (not shown) and electrically connected. The terminals of the connector 40 are electrically connected by contacting the terminals of the electronic circuit board 30 (shown in FIG. 3). Here, in this example, the case where the box-type electronic unit 1 includes one connector 40 is given as an example, but a plurality of connectors 40 may also be provided.

The box-type electronic unit 1 further includes an electromagnetic wave shielding member 50 exposed on the back surface of the resin case 10. The electromagnetic wave shield member 50 is a heat sink having a heat dissipation function. The electromagnetic wave shield member 50 is fitted in the heat dissipation opening 11a1 of the resin case 10. The electromagnetic wave shield member 50 having a heat dissipation function includes a plurality of protrusions protruding from the back surface of the resin case 10 in order to enhance the heat dissipation effect.

(3. Configuration of each element of the box-type electronic unit)
The configuration of each element of the box-type electronic unit 1 will be described with reference to FIGS. 3 to 5. As shown in FIG. 3, the box-shaped electronic unit 1 includes a resin case 10, a lid 20, an electronic circuit board 30, a connector 40, electromagnetic wave shielding members 50 and 60, a viscoelastic joining member 70, and viscoelasticity. A seal member 80 and a viscoelastic shield layer 90 are provided.

The resin case 10 is formed in a container shape by a resin material. The resin material forming the resin case 10 is a resin material having no conductivity. That is, the resin material does not have a shielding function. The resin material is formed of, for example, general-purpose plastics, engineering plastics, super engineering plastics, and the like. Specifically, the resin material is, for example, ABS, polypropylene, polycarbonate, polybutylene terephthalate, polyphenylene sulfide and the like.

Further, as shown in FIG. 4, the resin case 10 includes a case main body 11 and a partition plate 12, and is a member in which the case main body 11 and the partition plate 12 are integrally molded. The case body 11 is formed in the shape of a container that forms the internal space A0, and has a main opening above FIG. In this example, the case body 11 is formed in a rectangular container shape. As shown in FIG. 4, the case main body 11 includes a bottom surface 11a, a peripheral wall 11b erected on the peripheral edge of the bottom surface 11a, and a connector holding portion 11c. Therefore, the case body 11 has a main opening formed by the tip of the peripheral wall 11b.

The bottom surface 11a of the case body 11 is formed, for example, in the shape of a rectangular plate. As shown in FIG. 5, the bottom surface 11a includes a heat dissipation opening 11a1 penetrating in the normal direction of the bottom surface 11a. The heat dissipation opening 11a1 is an opening for discharging the heat generated by the electronic circuit board 30 to the outside. In this example, the heat dissipation opening 11a1 is a rectangular opening. Further, as shown in FIG. 5, the bottom surface 11a of the case body 11 is provided with a non-penetrating recess 11a2 on the outer surface side of the bottom surface 11a at a position different from the heat dissipation opening 11a1.

As shown in FIG. 4, the peripheral wall 11b of the case body 11 forms a space A0 for accommodating the electronic circuit board 30 inside. In this example, the peripheral wall 11b is provided on the entire peripheral edge of the bottom surface 11a. That is, the peripheral wall 11b is formed in a rectangular frame shape. Then, a rectangular main opening is formed by the tip of the peripheral wall 11b.

Outer seating surfaces 11b1 that support the four corners of the lid 20 are formed at the four corners of the peripheral wall 11b. Further, at the four corners of the internal space A0 formed from the peripheral wall 11b, inner seating surfaces 11b2 that support the four corners of the electronic circuit board 30 are formed.

As shown in FIG. 4, the connector holding portion 11c is formed in a part of the peripheral wall 11b. In this example, the connector holding portion 11c is a hole that penetrates one side of the peripheral wall 11b in the normal direction of the bottom surface 11a. As another example, the connector holding portion 11c may be a hole or a notch on one side of the peripheral wall 11b that penetrates in the surface direction of the bottom surface 11a.

As shown in FIG. 4, the partition plate 12 is provided in the internal space A0 of the case main body 11. The partition plate 12 is formed so that the base end is connected to the bottom surface 11a and faces the peripheral wall 11b. However, a part of the partition plate 12 is connected to the peripheral wall 11b. Therefore, the partition plate 12 partitions the internal space A0 of the case body 11 into a plurality of spaces A1, A2, A3, and A4.

Each of the plurality of spaces A1, A2, A3, and A4 has an electromagnetic wave shielding function. Here, the electromagnetic wave shielding function includes a function of reflecting an electromagnetic wave and a function of absorbing an electromagnetic wave. The spaces A1-A4 may all have the same electromagnetic wave shielding function, or may have different electromagnetic wave shielding functions.

In this example, the first space A1 is an electromagnetic wave absorbing space having a function of absorbing electromagnetic waves. The second space A2, the third space A3, and the fourth space A4 have a function of reflecting electromagnetic waves. Further, as shown in FIG. 3, the first space A1 is a rectangular space located at the center of the internal space A0 of the case body 11. The first space A1 is formed by the bottom surface 11a and the partition plate 12.

The second space A2 is a large space located on the side opposite to the connector holding portion 11c in the surroundings of the case main body 11 in the internal space A0. The second space A2 is formed by a bottom surface 11a, a part of the peripheral wall 11b, and a partition plate 12. Further, a heat dissipation opening 11a1 is formed on the bottom surface 11a forming the second space A2.

The third space A3 is a space located on the connector holding portion 11c side of the periphery of the internal space A0 of the case main body 11. The third space A3 is formed by a bottom surface 11a, a part of the peripheral wall 11b, and a partition plate 12. The fourth space A4 is a space located on the connector holding portion 11c side of the periphery of the internal space A0 of the case body 11. The fourth space A4 is formed by a bottom surface 11a, a part of the peripheral wall 11b, and a partition plate 12.

As shown in FIG. 3, the lid 20 closes the main opening of the case body 11, that is, the main opening formed by the tip of the peripheral wall 11b. The lid 20 is supported by the outer seating surface 11b1 of the peripheral wall 11b of the case body 11, and is fastened by a fastening member (not shown). Further, in this example, as shown in FIG. 3, the lid 20 is formed in a plate shape, for example, a rectangular plate shape. However, the lid 20 may be formed in a shape in which the case body 11 is turned upside down, that is, a shape having a space inside.

As shown in FIG. 5, the electronic circuit board 30 has an electronic circuit component 32 mounted on a board body 31. In this example, the electronic circuit component 32 is mounted on the lower surface side of FIG. 5 of the substrate main body 31, that is, the surface on the resin case 10 side. However, the electronic circuit component 32 may also be mounted on the upper surface side of FIG. 5 of the substrate main body 31, that is, the surface on the lid 20 side. The four corners of the electronic circuit board 30 are supported by the inner seating surface 11b2 of the peripheral wall 11b of the case body 11.

Here, as shown in FIG. 5, the electronic circuit board 30 has a plurality of compartments B1, B2, B3, and B4. The electronic circuit components arranged in the first section B1 are arranged in the first space A1, and the electronic circuit parts arranged in the second section B2 are arranged in the second space A2. The electronic circuit parts arranged in the third section B3 are arranged in the third space A3, and the electronic circuit parts arranged in the fourth section B4 are arranged in the fourth space A4.

Further, the electronic circuit board 30 is supported by the tip surface of the partition plate 12 in addition to the inner seat surface 11b2 of the peripheral wall 11b of the case body 11. That is, the central portion of the electronic circuit board 30 is supported by the partition plate 12. In particular, the partition plate 12 supports the boundary surface of each compartment B1-B4.

As shown in FIGS. 3 and 5, a part of the connector 40 is held by the connector holding portion 11c of the case body 11, and the remaining part of the connector 40 projects outward from the outer surface of the case body 11. .. In this example, the connector 40 may be formed in a straight line having an angle but not having an angle. Further, when the connector 40 has an angle, it can be any angle.

The case where the connector 40 is formed separately from the resin case 10 and the lid 20 is taken as an example. In addition to this, the connector 40 may be formed in the same shape as the case body 11 of the resin case 10. In this case, the case body 11 does not have the connector holding portion 11c, and a part of the connector 40 constitutes a wall surface forming the third space A3.

The electromagnetic wave shield member 50 has an electromagnetic wave shield function and a heat dissipation function. That is, the electromagnetic wave shield member 50 is a heat sink. The electromagnetic wave shield member 50 is formed of, for example, a metal material having good heat transfer characteristics such as aluminum, copper, and iron. Of course, the electromagnetic wave shield member 50 may be formed of a material other than the metal material. Therefore, the electromagnetic wave shield member 50 is formed separately from the resin case 10 by a material having a coefficient of thermal expansion different from that of the resin case 10.

The electromagnetic wave shield member 50 is arranged in the second space A2, which is one of the shield target areas of the resin case 10. The electromagnetic wave shield member 50 is attached to the heat dissipation opening 11a1 on the bottom surface 11a forming the second space A2. In this example, the electromagnetic wave shield member 50 is arranged so as not to be detached from the bottom surface 11a of the case body 11 by being fitted into the heat dissipation opening 11a1. In particular, the electromagnetic wave shield member 50 is locked to the bottom surface 11a in both directions along the normal of the bottom surface 11a.

Further, since the electromagnetic wave shield member 50 is arranged in the heat dissipation opening 11a1, it constitutes a part of the inner wall surface of the second space A2. That is, at least a part of the electromagnetic wave shield member 50 is exposed inside the second space A2. Further, since the electromagnetic wave shield member 50 is arranged in the heat dissipation opening 11a1, it is also exposed to the outside of the bottom surface 11a of the case body 11. The electromagnetic wave shield member 50 includes a plurality of protrusions 51 projecting to the outside of the bottom surface 11a in order to enhance the heat dissipation effect.

The electromagnetic wave shielding member 60 is an electromagnetic wave absorbing member having an electromagnetic wave absorbing function as an electromagnetic wave shielding function. The electromagnetic wave shield member 60 is formed separately from the resin case 10 by using a material having a coefficient of thermal expansion different from that of the resin case 10. The electromagnetic wave shielding member 60 includes, for example, a resin absorbing layer 61 and a metal layer 62. The material, thickness, and the like of the resin absorbing layer 61 are adjusted according to the frequency to be absorbed.

In addition to the above configuration, the electromagnetic wave shield member 60 can also be formed of any one of a conductive radio wave absorbing material, a dielectric radio wave absorbing material, and a magnetic radio wave absorbing material. The conductive radio wave absorbing material absorbs the current generated by the radio wave by the resistance inside the material. The dielectric radio wave absorbing material utilizes the dielectric loss caused by the polarization reaction of molecules, and is formed by mixing, for example, carbon or the like with a dielectric material such as rubber, urethane foam, or polyurethane foam. The magnetic radio wave absorbing material absorbs radio waves by the magnetic loss of the magnetic material, and absorbs radio waves by using iron, nickel, ferrite, or the like.

The electromagnetic wave shield member 60 is arranged in the first space A1, which is one of the shield target areas of the resin case 10. The electromagnetic wave shield member 60 is arranged on a part of the inner wall surface of the first space A1. In this example, the electromagnetic wave shield member 60 is attached to the bottom surface 11a forming the first space A1. The metal layer 62 of the electromagnetic wave shielding member 60 is adhered to the bottom surface 11a, and the resin absorbing layer 61 is adhered to the surface of the metal layer 62 opposite to the bottom surface 11a.

The viscoelastic joining member 70 is formed of a polymer viscoelastic material, and joins the connector holding portion 11c and the connector 40. In this example, the viscoelastic joining member 70 is interposed between the inner peripheral surface of the connector holding portion 11c and the outer peripheral surface of the connector 40, and is interposed between the inner peripheral surface of the connector holding portion 11c and the outer peripheral surface of the connector 40. It is joined. The viscoelastic bonding member 70 is formed of, for example, silicone rubber, ethylene propylene rubber, or the like. As will be described later, the viscoelastic joining member 70 is molded by injection molding. Therefore, the viscoelastic joining member 70 can easily and surely join the connector holding portion 11c and the connector 40. When the connector 40 is molded in the same shape as the case body 11, the viscoelastic seal member 70 becomes unnecessary.

The viscoelastic sealing member 80 is formed of a polymer viscoelastic material and is joined to the tip surface of the peripheral wall 11b of the case body 11. The viscoelastic sealing member 80 has a sealing function between the case body 11 of the resin case 10 and the lid 20. The viscoelastic seal member 80 is formed of, for example, the same material as the viscoelastic joining member 70. That is, the viscoelastic seal member 80 is formed of, for example, silicone rubber, ethylene propylene rubber, or the like.

Therefore, the viscoelastic seal member 80 is joined to the peripheral wall 11b of the case body 11, and can exhibit the sealing function by being brought into contact with the lid 20 in a compressed state. Further, as will be described later, the viscoelastic seal member 80 is molded by injection molding. Therefore, the viscoelastic seal member 80 can be easily molded.

The viscoelastic shield layer 90 is formed of a polymer viscoelastic material having electromagnetic wave shielding properties. The viscoelastic shield layer 90 is arranged on the inner wall surface forming the first space A1 to the fourth space A4, which is the electromagnetic wave shielding space in the resin case 10.

However, in the first space A1 and the second space A2, the viscoelastic shield layer 90 does not cover the entire region in the region where the electromagnetic wave shield members 50 and 60 are arranged, but the electromagnetic wave shield members 50 and 60. At least a part of is exposed. On the other hand, in the third space A3 and the fourth space A4, the viscoelastic shield layer 90 covers all the inner wall surfaces formed by the bottom surface 11a, the peripheral wall 11b, and the partition plate 12. Further, the viscoelastic shield layer 90 is also arranged on the tip surface of the partition plate 12.

In this example, the viscoelastic shield layer 90 is only arranged in the resin case 10 and not in the lid 20. However, the viscoelastic shield layer 90 may also be arranged on the lid 20.

For the viscoelastic shield layer 90, for example, a material in which a conductive filler is contained in a viscoelastic main component such as rubber or an elastomer is used. As the viscoelastic main component, synthetic rubber such as EPDM, NBR, acrylic rubber, fluororubber, silicone rubber, and chloroprene rubber is used. As the conductive filler, carbon black, metal particles, or the like is used.

Therefore, the viscoelastic shield layer 90 can surely exert the electromagnetic wave shielding effect in the first space A1 to the fourth space A4 as the shield target area. However, since the viscoelastic shield layer 90 is in a state where at least a part of the electromagnetic wave shield members 50 and 60 is exposed, it is possible to maintain a state in which the electromagnetic wave shield members 50 and 60 exert their functions. That is, the heat dissipation effect can be exerted by the exposed portion of the electromagnetic wave shield member 50, and the electromagnetic wave absorption function can be exerted by the exposed portion of the electromagnetic wave shield member 60. Further, as will be described later, the viscoelastic shield layer 90 is molded by injection molding. Therefore, the viscoelastic shield layer 90 can be easily molded.

(4. Details of electromagnetic wave shielding function in the first space A1)
The details of the electromagnetic wave shielding function in the first space A1 will be described with reference to FIG. An electromagnetic wave shield member 60 having an electromagnetic wave absorbing function is arranged in the first space A1. Specifically, the electromagnetic wave shield member 60 is arranged on the bottom surface 11a forming the inner wall surface of the first space A1. In particular, the metal layer 62 constituting the electromagnetic wave shielding member 60 is adhered to the bottom surface 11a, and the resin absorbing layer 61 is laminated on the metal layer 62.

The viscoelastic shield layer 90 covers the inner wall surface of the first space A1 in a region other than the region where the electromagnetic wave shield member 60 is arranged. In this example, the viscoelastic shield layer 90 covers all the surfaces of the inner wall surface of the first space A1 except for the region where the electromagnetic wave shield member 60 is arranged. Here, the inner wall surface of the first space A1 means a surface formed by the resin case 10, and does not include the main opening side of the resin case 10, that is, the surface on which the electronic circuit substrate 30 is arranged.

Further, the viscoelastic shield layer 90 is arranged so as to straddle the resin case 10 and the electromagnetic wave shield member 60 in a state of being in contact with the resin case 10 and the electromagnetic wave shield member 60. Specifically, in the first space A1, the viscoelastic shield layer 90 straddles the bottom surface 11a or the partition plate 12 and the peripheral edge of the metal layer 62 of the electromagnetic wave shield member 60. More specifically, the viscoelastic shield layer 90 extends over the entire periphery of the metal layer 62 except for the central portion of the metal layer 62.

That is, the viscoelastic shield layer 90 is continuously arranged from the surface of the inner wall surface of the first space A1 excluding the region where the electromagnetic wave shield member 60 is arranged to the electromagnetic wave shield member 60.

Therefore, at least one of the electromagnetic wave shield member 60 and the viscoelastic shield layer 90 is present on the inner wall surface forming the first space A1. In particular, in the portion of the viscoelastic shield layer 90 that is in contact with the electromagnetic wave shield member 60, both the viscoelastic shield layer 90 and the electromagnetic wave shield member 60 are present. That is, the electromagnetic wave shielding function can be exhibited on all surfaces of the inner wall surface of the first space A1.

Further, the viscoelastic shield layer 90 is arranged so as to straddle the resin case 10 and the electromagnetic wave shield member 60 in a state of being in contact with the electromagnetic wave shield member 60. Here, the resin case 10 and the electromagnetic wave shielding member 60 are formed of materials having different coefficients of thermal expansion. Therefore, the relative position of the resin case 10 and the electromagnetic wave shield member 60 changes due to the temperature change. However, even if the relative position changes, the viscoelastic shield layer 90 can follow the change in the relative position between the resin case 10 and the electromagnetic wave shield member 60. Therefore, the desired electromagnetic wave shielding function can be exhibited.

Further, the metal layer 62 constituting the electromagnetic wave shielding member 60 includes a laminated portion 62a that is laminated and adhered to the resin absorbing layer 61, and a flange portion 62b that projects outward from the outer periphery of the laminated portion 62a. The viscoelastic shield layer 90 straddles the bottom surface 11a or the partition plate 12 and the flange portion of the metal layer 62. By making the viscoelastic shield layer 90 continuous with the metal layer 62, the electromagnetic wave reflection function can be continuously exhibited in the first space A1.

On the other hand, the viscoelastic shield layer 90 is not arranged so as to overlap the resin absorbing layer 61 having an electromagnetic wave absorbing function. Therefore, it is possible to prevent the viscoelastic shield layer 90 from adversely affecting the electromagnetic wave absorbing function of the resin absorbing layer 61. That is, it is possible to exert a desired electromagnetic wave absorption function.

(5. Details of electromagnetic wave shielding function in the second space A2)
The details of the electromagnetic wave shielding function in the second space A2 will be described with reference to FIG. An electromagnetic wave shield member 50 having a heat dissipation function is arranged in the second space A2. Specifically, the electromagnetic wave shield member 50 is fitted in the heat dissipation opening 11a1 on the bottom surface 11a.

The viscoelastic shield layer 90 covers the inner wall surface of the second space A2 in a region other than the region where the electromagnetic wave shield member 50 is arranged. In this example, the viscoelastic shield layer 90 covers all the surfaces of the inner wall surface of the second space A2 except the region where the electromagnetic wave shield member 50 is arranged. Here, the inner wall surface of the second space A2 means a surface formed by the resin case 10 and the electromagnetic wave shielding member 50, and includes the main opening side of the resin case 10, that is, the surface on which the electronic circuit board 30 is arranged. No.

Further, the viscoelastic shield layer 90 is arranged so as to straddle the resin case 10 and the electromagnetic wave shield member 50 in a state of being in contact with the resin case 10 and the electromagnetic wave shield member 50. Specifically, the viscoelastic shield layer 90 straddles the bottom surface 11a, the peripheral wall 11b or the partition plate 12, and the electromagnetic wave shield member 50. More specifically, the viscoelastic shield layer 90 straddles the entire peripheral edge of the heat dissipation opening 11a1 on the bottom surface 11a and the entire peripheral edge of the electromagnetic wave shielding member 50 excluding the central portion of the electromagnetic wave shielding member 50.

Therefore, at least one of the electromagnetic wave shield member 50 and the viscoelastic shield layer 90 exists on the inner wall surface forming the second space A2. In particular, in the portion of the viscoelastic shield layer 90 that is in contact with the electromagnetic wave shield member 50, both the viscoelastic shield layer 90 and the electromagnetic wave shield member 50 are present. That is, the electromagnetic wave shielding function can be exhibited on all surfaces of the inner wall surface of the second space A2.

Further, the viscoelastic shield layer 90 is arranged so as to straddle the resin case 10 and the electromagnetic wave shield member 50 in a state of being in contact with the electromagnetic wave shield member 50. Here, the resin case 10 and the electromagnetic wave shielding member 50 are formed of materials having different coefficients of thermal expansion. Therefore, the relative position of the resin case 10 and the electromagnetic wave shield member 50 changes due to the temperature change. However, even if the relative position changes, the viscoelastic shield layer 90 can follow the change in the relative position between the resin case 10 and the electromagnetic wave shield member 50. Therefore, the desired electromagnetic wave shielding function can be exhibited.

Further, the viscoelastic shield layer 90 is in a state where at least a part of the electromagnetic wave shield member 50 is exposed. Here, the electromagnetic wave shield member 50 is a member having a heat dissipation function. That is, the viscoelastic shield layer 90 is not arranged so as to overlap at least a part of the electromagnetic wave shield member 50. Therefore, it is possible to prevent the viscoelastic shield layer 90 from adversely affecting the heat dissipation function of the electromagnetic wave shield member 50. That is, the exposed portion of the electromagnetic wave shield member 50 can exert a heat dissipation function.

Further, the electromagnetic wave shield member 50 is fitted into the heat dissipation opening 11a1 formed on the bottom surface 11a of the case body 11 of the resin case 10. As shown in FIG. 5, in the fitted state, the bottom surface 11a of the resin case 10 and the surface of the electromagnetic wave shielding member 50 form a stepped shape. The viscoelastic shield layer 90 is arranged at a stepped portion so as to straddle the bottom surface 11a of the resin case 10 and the electromagnetic wave shield member 50.

More specifically, the layer thickness of the viscoelastic shield layer 90 is formed so that the layer thickness at the stepped step portion is thicker than the layer thickness around the stepped step portion. The thicker the layer, the higher the displacement followability. That is, by forming the layer thickness as described above, even if the relative positions of the resin case 10 and the electromagnetic wave shield member 50 change, the viscoelastic shield layer 90 more reliably secures the resin case 10 and the electromagnetic wave shield. It is possible to follow a change in the position relative to the member 50.

(6. Electromagnetic wave shielding function on the tip surface of the partition plate 12)
As shown in FIG. 5, the viscoelastic shield layer 90 is also arranged on the tip surface of the partition plate 12. That is, the viscoelastic shield layer 90 is arranged on each inner wall surface (side wall surface of the partition plate 12) forming an adjacent space and the tip surface of the partition plate 12 located at the boundary portion with each inner wall surface. ing. More specifically, the viscoelastic shield layer 90 is continuously arranged on the inner wall surface of each of the adjacent spaces and the tip surface of the partition plate 12.

For example, the viscoelastic shield layer 90 is continuously arranged on the inner wall surface forming the first space A1, the tip surface of the partition plate 12 which is the boundary of the inner wall surface, and the inner wall surface forming the second space A2. ing. First space A1 and third space A3, first space A1 and fourth space A4, second space A2 and third space A3, second space A2 and fourth space A4, third space A3 and fourth space A4 The same applies to each boundary portion.

The viscoelastic shield layer 90 arranged on the tip surface of the partition plate 12 supports the electronic circuit board 30. Therefore, even if the position of the electronic circuit board 30 with respect to the resin case 10 changes, the viscoelastic shield layer 90 can follow it. Therefore, the viscoelastic shield layer 90 can surely exert a desired electromagnetic wave shielding function between the electronic circuit board 30 and the partition plate 12. Further, the central portion of the electronic circuit board 30 is supported by the partition plate 12 via the viscoelastic shield layer 90, so that the electronic circuit board 30 can be in a stable posture.

(7. Manufacturing method of box-type electronic unit 1)
A method for manufacturing the box-type electronic unit 1 will be described with reference to FIGS. 5 to 10. As shown in FIG. 6, the electromagnetic wave shielding member 50 as an insert is arranged in the first mold (not shown) (step S1). The resin case 10 is molded by supplying the resin material into the first mold (step S2). As a result, the product 1a shown in FIG. 7 is produced. At this time, the electromagnetic wave shield member 50 is fitted into the bottom surface 11a of the case body 11 of the resin case 10. Therefore, the electromagnetic wave shield member 50 is fixed to the resin case 10.

Subsequently, the metal layer 62 of the electromagnetic wave shielding member 60 is adhered to the bottom surface 11a of the first space A1 of the resin case 10 (step S3). The metal layer 62 can also be insert-molded in step S2 together with the electromagnetic wave shielding member 50. Further, a metal layer 62 and a resin absorbing layer 61 integrated in advance may be adhered to the bottom surface 11a of the first space A1, or the integrated material may be insert-molded in step S2. Subsequently, the connector 40 as an insert is arranged in the second mold (not shown) (step S4). The object 1b in the second type at this time is as shown in FIG.

Subsequently, the viscoelastic joint member 70, the viscoelastic seal member 80, and the viscoelastic shield layer 90 are formed by supplying the viscoelastic material into the second mold (step S5). As a result, the product 1c shown in FIG. 9 is produced. Here, the viscoelastic joining member 70 and the viscoelastic sealing member 80 are formed of the same material, and the viscoelastic shield layer 90 is formed of a material different from that of the viscoelastic joining member 70 and the like. Therefore, two-color molding is performed here.

Subsequently, the resin absorbing layer 61, which is the remaining member of the electromagnetic wave shielding member 60, is arranged (step S6). Subsequently, the electronic circuit board 30 is attached (step S7). As a result, the product 1d shown in FIG. 10 is produced. Subsequently, by attaching the lid 20, the box-shaped electronic unit 1 shown in FIG. 5 is completed (step S8).

According to the above manufacturing method, in step S5, the viscoelastic joining member 70, the viscoelastic sealing member 80, and the viscoelastic shield layer 90 can be molded in one step. Therefore, the manufacturing cost is low.

(7. Others)
In the above, the example in which the viscoelastic shield layer 90 is arranged on the inner wall surface of the resin case 10 has been given. In addition, the viscoelastic shield layer 90 may be arranged on the outer wall surface of the resin case 10. In this case, the viscoelastic shield layer 90 is exposed to the outside.

1: Box type electronic unit, 10: Resin case, 11: Case body, 11a: Bottom surface, 11a1: Heat dissipation opening, 11a2: Recession, 11b: Peripheral wall, 11b1: Outer seat surface, 11b2: Inner seat surface, 11c: Connector holding part, 12: Partition plate, 20: Lid, 30: Electronic circuit board, 31: Board body, 32: Electronic circuit parts, 40: Connector, 50: Electromagnetic wave shield member, 51: Projection, 60: Electromagnetic wave shield member, 61: Resin absorbing layer, 62: Metal layer, 62a: Laminated part, 62b: Flange part, 70: Viscoelastic joining member, 80: Viscoelastic sealing member, 90: Viscoelastic shield layer, A0: Internal space, A1: First One space, A2: Second space, A3: Third space, A4: Fourth space, B1: First section, B2: Second section, B3: Third section, B4: Fourth section

Claims (8)

Electronic circuit board and
A resin case for accommodating the electronic circuit board and
An electromagnetic wave shield member formed separately from the resin case by a material having a coefficient of thermal expansion different from that of the resin case, attached to the resin case, and at least partially exposed.
A viscoelastic shield layer formed of a polymer viscoelastic material having an electromagnetic wave shielding property and arranged so as to straddle the resin case and the electromagnetic wave shielding member in contact with the resin case and the electromagnetic wave shielding member.
A box-type electronic unit equipped with. The electromagnetic wave shield member is arranged in a part of the shield target area of the resin case, and is arranged.
The viscoelastic shield layer covers the inner wall surface or the outer wall surface of the shield target region of the resin case in a region other than the region where the electromagnetic wave shield member is arranged, and further extends continuously to the electromagnetic wave shield member. The box-type electronic unit according to claim 1, which is arranged. The resin case has a through opening for heat dissipation.
The electromagnetic wave shield member is a heat sink and is fitted into the heat dissipation opening.
The box-shaped electronic unit according to claim 1 or 2, wherein the viscoelastic shield layer is arranged so as to straddle the peripheral edge of the heat dissipation opening of the resin case and the heat sink. The surface of the resin case and the surface of the heat sink form a stepped shape.
The viscoelastic shield layer is arranged so as to straddle the resin case and the heat sink at the stepped portion.
The box type according to claim 3, wherein the layer thickness of the viscoelastic shield layer is formed so that the layer thickness at the stepped portion is thicker than the layer thickness around the stepped portion. Electronic unit. The resin case has an electromagnetic wave absorption space and has an electromagnetic wave absorption space.
The electromagnetic wave shielding member is an electromagnetic wave absorbing member arranged on a part of the inner wall surface of the electromagnetic wave absorbing space of the resin case.
The viscoelastic shield layer covers the inner wall surface of the electromagnetic wave absorbing space in a region other than the region where the electromagnetic wave shielding member is arranged, and is further arranged continuously up to the electromagnetic wave absorbing member. Or the box-type electronic unit according to 2. The electromagnetic wave absorbing member includes a resin absorbing layer and a metal layer laminated on the resin absorbing layer.
The box-shaped electronic unit according to claim 5, wherein the viscoelastic shield layer is arranged so as to straddle the resin case and the metal layer of the electromagnetic wave absorbing member. The metal layer includes a laminated portion that is laminated and adhered to the resin absorbing layer, and a flange portion that projects outward from the outer periphery of the laminated portion.
The box-shaped electronic unit according to claim 6, wherein the viscoelastic shield layer is arranged so as to straddle the resin case and the flange portion of the metal layer of the electromagnetic wave absorbing member. The electronic circuit board has a first section and a second section.
The resin case is
Container-shaped case body and
A partition plate that divides the internal space of the case body into a first space and a second space, and supports a boundary surface between the first section and the second section of the electronic circuit board at the tip surface, and a partition plate.
With
The viscoelastic shield layer is continuously arranged on the inner wall surface forming the first space, the tip surface of the partition plate, and the inner wall surface forming the second space.
The box-shaped electron according to any one of claims 1-7, wherein the portion of the viscoelastic shield layer arranged on the tip surface of the partition plate is arranged in contact with the electronic circuit substrate. unit.

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