JP2009164243A - Electromagnetic wave shielding resin molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To actualize more effective protection of an electronic component by protection step in cooperation of resin and metal mesh in a mounting substrate provided with loaded electronic components or the like. <P>SOLUTION: The electromagnetic wave shielding resin molding 11 is provided with a metal mesh 32 for core at the core part 31a of a printed circuit board 21 mounting electronic components 41 and is also provided with a metal mesh 39 at a part covering the upper surface and the circumferential surface of the mounted electronic components 41. Moreover, a resin layer 31b and a resin part 61 including these metal meshes 32, 39 are also provided. The resin part 61 is provided directly to cover the mounted electronic components 41. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin molded product used as, for example, a housing of a device on which electronic components are mounted, a printed wiring board, a printed circuit board, and the like, and more specifically, shields electromagnetic waves and externally mounts the mounted electronic components. The present invention relates to an electromagnetic wave shielding resin molded product that can protect against electromagnetic waves and prevent leakage of electromagnetic waves emitted from electronic components.

  Sealing molding is generally performed to protect electronic components mounted on a printed circuit board from dust, moisture, and the like. For example, as disclosed in FIG. 5 of Patent Document 1 below, sealing molding is performed by setting a printed circuit board mounted with electronic components in a mold and then injecting a thermoplastic resin into the mold. The electronic component is sealed.

  The resin used for sealing is flexible in order to avoid damage such as deformation and peeling of electronic parts and bonding wires due to molding pressure during molding, and to obtain shock absorption. Is preferred.

  Furthermore, in the case of a power system mounting board, the component thermally expands due to the heat generated by the electronic component. Therefore, the resin is preferably a flexible resin so that the expansion can be absorbed.

  On the other hand, it is preferable to use a hard resin in order to protect the electronic component by strengthening the external force.

  In this regard, although potting can avoid the above-mentioned inconveniences, potting generally uses a liquid thermosetting resin, so that it takes a long time to cure. In addition, a container is necessary for molding, and there are problems that the number of parts increases, the manufacturing process becomes complicated, and the manufacturing cost increases.

  By the way, shielding electromagnetic waves from inside and outside is also important in protecting electronic components. For shielding electromagnetic waves, for example, a method of covering a metal mesh as disclosed in Patent Document 2 below is known.

JP 2003-133703 A JP 2005-294313 A

  However, the metal mesh only has an electromagnetic wave shielding effect and cannot provide a protective effect as in the case of using a resin.

  In view of the above, an object of the present invention is to realize more effective protection of an electronic component by cooperation between a resin and a metal mesh.

  Means for this is an electromagnetic wave shielding resin molded product in which a metal mesh is provided in a portion surrounding a portion where an electronic component is mounted, and a resin portion is formed by molding a resin so as to enclose the metal mesh. .

The resin part may be one that directly covers and seals the electronic component.
Moreover, the said resin part is a hollow box-shaped housing | casing, Comprising: The said metal mesh may be provided in thickness.

  When the electromagnetic wave shielding resin molded product is a printed wiring board or a printed circuit board, the metal member may be provided in the core portion of the printed wiring board on which the electronic component is mounted.

In this case, the metal mesh surrounding the electronic component mounting portion of the printed wiring board further has a conductive portion inserted into a through hole provided in the printed wiring board, and the conductive portion is a core of the printed wiring board. It may be electrically connected to the metal member of the part through a through hole.
For the metal member, for example, a metal mesh can be used.

  As described above, according to the present invention, the resin part is made of a resin that encloses the metal mesh, and the resin part surrounds the electronic part. Therefore, the electronic part is covered with the resin and the metal mesh. In addition to having the effect of shielding electromagnetic waves, protection from dust, moisture and impact can be achieved. Moreover, since the resin part contains the metal mesh, even if the resin is soft, impact resistance can be obtained in cooperation with the metal mesh.

  Further, since the metal mesh surrounding the electronic component in the resin portion transmits and emits heat generated from the electronic component, the electronic component can be protected also in this respect. In addition, the metal mesh covering the electronic component can also have a function as a ground.

An embodiment for carrying out the present invention will be described below with reference to the drawings.
1 is a cross-sectional view of an electromagnetic wave shielding resin molded article 11 (hereinafter referred to as “molded product”) obtained by overmolding (sealing all around) a printed circuit board 21 (mounting board) on which electronic components 41... Are mounted. It is. FIG. 7 is a perspective view of the molded product 11 in which the mounting substrate itself functions as a casing of the electronic component mounting device. As shown in these drawings, the part surrounding the portion where the electronic component 41 is mounted is intended to realize more effective protection of the electronic component 41 by the cooperation of the resin and the metal mesh. This is realized by a configuration in which a metal mesh 39 is provided, and a resin portion 61 formed by molding a resin so as to enclose the metal mesh 39 is provided.

  The above-mentioned Go means not only covering all four sides of the electronic components 41, but also covering a part thereof. Further, the resin portion 61 may cover the electronic components 41... Directly or in a non-contact manner. That is, the electronic component 41 is directly covered and sealed as in the molded product 11 shown in FIG. 1, or a part of the periphery of the electronic component 41 is surrounded as in the molded product 11 shown in FIG. Can also be covered.

  This will be specifically described below.

  The molded product 11 shown in FIG. 1 is obtained by sealing the entire printed circuit board 21 as described above. That is, the printed circuit board 21 on which the electronic component 41 is mounted as shown in FIG. 3 is sealed and formed on the printed wiring board 31 manufactured as shown in FIG. 2 (see FIGS. 4 and 5). Manufactured.

First, the printed wiring board 31 will be described.
The printed wiring board 31 is a metal core substrate, and the core is composed of a core metal mesh 32 having conductivity as a metal member. As schematically shown in FIG. 2, the manufacturing is performed by cutting and punching a sheet-like metal mesh for core 32 (see FIG. 2 (a)) (see FIG. 2 (b)), and a laminated integration process (see FIG. 2). (See FIGS. 2C and 2D) and necessary steps (not shown) such as through-hole formation, through-hole plating, wiring pattern formation, laminated integration of prepreg and copper foil, wiring pattern formation, solder resist, etc. The desired printed wiring board 31 is obtained.

  The core metal mesh 32 is woven with copper wire, nickel wire, aluminum wire, silver wire or the like. It can also be composed of expanded metal or punched metal.

  The above-described cutting and drilling step is a step of cutting the core metal mesh 32, which is a material, into a predetermined size and shape and opening the through holes 33 at necessary positions. The through-hole 33 is formed by appropriate means such as metal processing using a die and a punch, drilling, and the like, whereby a perforated base material 34 as a core is obtained.

  The lamination integration step is a step of heat-pressing the prepreg 35 and the copper foil 36 in order on both surfaces of the perforated base material 34 serving as a core. The hot press is performed by applying heat and pressure in a vacuum atmosphere, filling the melted resin of the prepreg 35 into the through-holes 33 of the perforated base material 34, etc., and achieving adhesion between the resin and the perforated base material 34. . By this lamination integration, a copper-clad laminate 37 in which a resin layer 31b for insulation and a conductive layer 31c made of copper foil 36 are disposed on both surfaces of a core 31a made of a perforated base material 34 is obtained. A part of the copper foil 36 later becomes a wiring pattern 36a (see FIGS. 1 and 2E).

In this integration, the resin of the prepreg 35 melted by heat flows into the mesh of the core metal mesh 32 as well as the through-holes 33, and the inflowed resin fills the gaps between the metal wires. It is connected from both the front and back surfaces in a state, and is integrated with a perforated base material 34 interposed. For this reason, since the adhesion is good and the anchor effect is high, roughening treatment such as blackening treatment becomes unnecessary. In addition, the spread of the resin to the side is suppressed, no voids due to insufficient resin content occur, and the thickness becomes uniform.
The core 31a can be made of a copper plate or other materials.

  The through hole 38 is formed at the position corresponding to the required through hole 33 among the through holes 33 of the perforated base material 34, and is formed to be the same as or smaller than the through hole 33, and the through hole plating 38a is performed later. When conductivity is imparted to the inner surface of the through hole 38, the conductive layers 31c on the front and back sides can be electrically connected (see FIG. 2E).

  As shown in FIG. 3, on the printed wiring board 31 manufactured in this manner, necessary electronic components 41 are mounted, and an upper side and an outer peripheral side of a portion where the electronic components 41 are mounted are arranged. A conductive metal mesh 39 is attached to the surrounding portion. The metal mesh 39 is woven with nickel wire, aluminum wire, silver wire, etc. in addition to copper wire. It can also be composed of expanded metal or punched metal.

  The electronic parts 41 on the printed wiring board 31 are entirely surrounded by the metal mesh 39 and the core metal mesh 32 of the core 31a.

  In addition, when attaching the metal mesh 39, the core metal mesh 32 is formed into a predetermined shape in advance, and a part of the metal mesh 39 is inserted into the through-hole 38 that is electrically connected to the core metal mesh 32 serving as the core 31a. The conducting portion 39a is provided. That is, the metal mesh 39 is connected to the core metal mesh 32 serving as the core 31a by the through hole 38, and can be used as a ground. At the same time, the metal mesh 39 and the core metal mesh 32 as the core 31a also serve to transmit and release heat generated from the electronic components 41.

  The printed circuit board 21 on which the electronic components 41... Are mounted and the metal mesh 39 is attached is held in a mold 53 including an upper mold 51 and a lower mold 52 as shown in FIG. 5), a resin is injected and molded. Molding is performed by hot melt molding. As the resin, for example, a thermoplastic polyamide hot melt, a polyolefin hot melt, a polyester hot melt, or the like can be used. In addition, although it is a thermosetting resin, an epoxy resin or a urethane resin can also be used.

  The resin directly contacts the upper surface of the printed circuit board 21 and the electronic components 41 through the metal mesh 39 and is molded into a shape corresponding to the mold 51 so as to enclose the metal mesh 39. Become.

  After molding, if the mold is released, the molded product 11 in which the entire printed circuit board 21 is sealed in the resin portion 61 as shown in FIG. 1 is obtained.

When the molded article 11 thus obtained was subjected to (1) water-stop test, (2) impact drop test, (3) heat resistance test, and (4) electromagnetic wave shielding test, the following evaluation was obtained. It was.
(1) Water-stop test
A 3000 cycle temperature impact test at −30 to 120 ° C. was performed on the molded product 11. Then, after being immersed in a water tank filled with ink-colored water and kept at a depth of 1 m for 24 hours, the molded product was taken out and the cross section was observed. As a result, it was confirmed that water did not enter. The resin part 61 was molded using Henkel hot melt, “shore D48” hardness.
(2) Impact drop test
The molded product 11 was dropped from a height of 1 m. It was confirmed that there was no problem in the operation of electronic components after dropping.
(3) Heat resistance test
The molded article 11 was continuously operated for 3 months in an environment of 85 ° C. and a humidity of 85%. As a result, no functional loss was observed.
Electromagnetic wave shielding test
In the molded product 11 using a metal mesh made of copper wire for the core metal mesh 32 in the core 31a portion and the metal mesh 39 in the portion covering the electronic component mounting portion, the difference in opening between the core metal mesh 32 and the metal mesh 39 The first test (see FIG. 6 (a)) that tests the shielding effect by the second test, and the second test that tests the difference in shielding effect when the materials constituting the core metal mesh 32 and the metal mesh 39 are different (FIG. 6 ( b)).

  In the test, the shielding effect against electromagnetic waves in the frequency band of 10 MHz to 10 GHz was examined using the KEC (Kansai Electronics Industry Promotion Center) method. The wire diameter is the thickness of the metal wire, and the opening is the interval between the metal wires. The mesh of the core metal mesh 32 and the metal mesh 39 is formed in a square shape.

  According to the results of the first test, it can be seen that the smaller the opening, the higher the electromagnetic shielding effect (see FIG. 6A).

  According to the result of the second test, it can be seen that even if the wire diameter and the opening are the same, the electromagnetic wave shielding effect varies depending on the material (see FIG. 6B). Moreover, it turns out that it is preferable to use copper and silver as a conductive metal.

  As described above, since the electronic components 41 are entirely surrounded by the core metal mesh 32 serving as the core 31a and the metal mesh 39, an electromagnetic wave shielding effect can be obtained. As a result, electronic components can be protected from external electromagnetic waves, and leakage of electromagnetic waves emitted from the electronic components can be prevented. In addition, since the resin part 61 includes the metal mesh 39, the metal mesh 39 performs a reinforcing function even if the resin is soft, and the rigidity is increased and impact resistance can be obtained. Further, the electronic components 41 can be protected from dust and moisture.

  Moreover, since the resin portion 61 molded so as to take in the metal mesh 39 directly covers and seals the electronic components 41, the electronic components 41 are protected from intrusion of dust, moisture, impact, and the like. Since the effect is extremely high and a flexible resin can be suitably used as described above, the electronic parts 41 and bonding wires are prevented from being damaged by the molding pressure at the time of molding, and shock absorption and thermal expansion of the electronic parts 41 are prevented. This is advantageous in that it can be absorbed.

  Further, the core metal mesh 32 and the metal mesh 39 surrounding the electronic components 41 in the resin layer 31b and the resin portion 61 transmit and emit heat generated from the electronic components 41. Therefore, it is possible to protect the electronic components 41 from the viewpoint of heat dissipation.

  In addition, the metal mesh 39 covering the electronic components 41... Also functions as a ground, and thus has an effect of suppressing noise.

  Next, the molded product 11 shown in FIG. 7 will be described. In this description, parts that are the same as or equivalent to the structure described above are given the same reference numerals, and detailed descriptions thereof are omitted.

  The molded product 11 shown in FIG. 7 is a casing of an electronic device such as a mobile phone. The molded product 11 is not mounted with a printed circuit board having electronic components mounted on a printed wiring board, but directly with necessary electronic components 41.

  In addition, the molded product 11 before mounting the electronic components 41 has a function as a printed wiring board. In FIG. 7, the wiring pattern 36a and the electronic components 41... On the inner bottom surface 11a of the molded product 11 are appropriately omitted for convenience. 7 and 10, a portion indicated by a broken line indicates a metal mesh 39 surrounding a portion where the electronic components 41 are mounted.

  The molded product 11 serving as a housing is manufactured, for example, in the shape of a bottomed box by molding a copper-clad laminate 37 as shown in FIG. The copper clad laminate 37 is manufactured so that the copper foil 36 exists on the surface corresponding to the inner bottom surface 11a of the housing after molding. That is, as shown in FIG. 9, the prepregs 35 and 35 and the copper foil 36 are disposed on one surface of the metal mesh 39 located at the middle portion in the thickness direction, and the other surface. The prepregs 35 and 35 are positioned on the substrate, and these are laminated and integrated by hot pressing. In the laminated copper-clad laminate 37, the metal mesh 39 is included in the resin portions 61 on both sides, and the conductive layer 31c made of the copper foil 36 is provided on one side of the resin layer 31b.

  Although the prepreg 35 is impregnated with a resin, a thermoplastic resin or an elastomer may be used as the resin. Also, instead of using a prepreg, a metal mesh 39 impregnated with a resin can be used.

  The molding is performed by raising the temperature to the softening temperature between a pair of dies 73 including a male die 71 and a female die 72 as shown in FIG. And do it. After molding, the copper foil 36 surrounded by the metal mesh 39 is etched to form a wiring pattern 36a (see FIG. 7), and unnecessary portions such as the outer periphery may be cut off.

  Even in the molded article 11 configured as described above, an electromagnetic wave shielding effect can be obtained without using a separate electromagnetic wave shielding sheet material or the like, as in the case of Example 1. Moreover, since the member surrounding the electronic component is not a metal plate but a metal mesh 39, it is easy to perform heat compression molding as described above, and various housings can be obtained. It is lighter than that.

  Since the electronic parts 41 are surrounded by the metal mesh 39, an electromagnetic wave shielding effect can be obtained. In addition, since the resin part 61 includes the metal mesh 39, the electronic components 41 can be protected from dust, moisture, and impact, and the resin constituting the resin part 61 is soft. In addition, the metal mesh 39 performs a reinforcing function, and the rigidity is increased to obtain impact resistance.

  Further, the metal mesh 39 surrounding the electronic components 41 in the resin portion 61 transmits heat emitted from the electronic components 41 to release it. Therefore, it is possible to protect the electronic components 41 from the viewpoint of heat dissipation.

In the correspondence between the configuration of the present invention and the configuration of the above-described embodiment,
The metal member of the present invention corresponds to the metal mesh 32 for the core,
The present invention is not limited to the above-described configuration, and other forms can be adopted.

  For example, the formation of the resin portion by sealing molding may be performed partially instead of the entire printed circuit board.

Sectional drawing of an electromagnetic wave shielding resin molded product. Sectional drawing which shows the outline manufacturing process of a printed wiring board. Sectional drawing which shows the mounting state to a printed wiring board. Sectional drawing which shows the metal mold | die for mounting, and a mounting substrate. Sectional drawing of the state which accommodated the mounting board | substrate in the cavity of the metal mold | die for shaping | molding. The test result which shows an electromagnetic wave shielding effect. The perspective view of an electromagnetic wave shielding resin molded product. Sectional drawing which shows the copper clad laminated board before shaping | molding. Sectional drawing of the decomposition | disassembly state of a copper clad laminated board. Sectional drawing which shows a formation process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Electromagnetic shielding resin molded product 21 ... Printed circuit board 31 ... Printed wiring board 31a ... Core 31b ... Resin layer 32 ... Metal mesh for core 38 ... Through hole 39 ... Metal mesh 39a ... Conductive part 41 ... Electronic component 61 ... Resin part

Claims (6)

A metal mesh is provided in the part surrounding the part where the electronic component is mounted,
An electromagnetic wave shielding resin molded product provided with a resin portion formed by molding a resin so as to enclose the metal mesh. The electromagnetic wave shielding resin molded product according to claim 1, wherein the resin portion directly covers and seals the electronic component. The electromagnetic wave shielding resin molded product according to claim 1, wherein the resin portion is a hollow box-shaped housing, and the metal mesh is provided in a wall thickness. The electromagnetic wave shielding resin molded product according to claim 1 or 2, wherein a metal member is provided in a core portion of a printed wiring board on which an electronic component is mounted. The metal mesh surrounding the electronic component mounting portion of the printed wiring board has a conductive portion inserted into a through hole provided in the printed wiring board,
The electromagnetic wave shielding resin molded product according to claim 4, wherein the conductive portion is electrically connected to the metal member of the core portion of the printed wiring board through a through hole. The electromagnetic wave shielding resin molded product according to claim 4, wherein the metal member is made of a metal mesh.

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