JP2011054888A - Shield structure and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shield structure capable of surely shielding an electronic apparatus surrounded by a shield frame even if a quantity of an adhesive agent for adhering the shield frame is large. <P>SOLUTION: A shield structure for shielding an electronic apparatus disposed on a printed board comprises a shield frame adhered on the printed board by a brazing adhesive agent while the electronic apparatus is surrounded and a shield top panel covering an upper part of the shield frame. The shield top panel comprises a strip sagging from its outer edge, and the strip is removed from a corner of the top panel corresponding to a corner of the shield frame. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a shield structure for shielding electronic components.

Shield that blocks noise from electronic components so that the noise generated by the operation of the electronic components does not affect other electronic components or is not affected by noise generated by other electronic components A structure is provided.
For example, in Patent Document 1, the electronic component that constitutes the analog circuit unit is shielded, so that the radiation noise from the semiconductor component that constitutes the digital circuit unit is prevented from being disturbed by the electronic component that constitutes the analog circuit unit. Techniques for mitigating are disclosed.

In the technique disclosed in Patent Document 1, shielding is performed for each electronic component constituting the analog circuit unit. As a conventional assembling method in such a case, there is a method of soldering a shield frame surrounding an electronic component on a printed circuit board and covering this with a shield cover.
An example of the process by this method is shown in FIG.

  First, as shown in FIG. 5A, cream solder is printed on the upper surface of the printed circuit board 130 using a metal mask. At this time, the cream solder is printed with a thickness of about 0.12 mm so that the distance after soldering (hereinafter referred to as flatness) between the upper surface of the printed circuit board 130 and the lower end of the shield frame is 0.10 mm or less. The Next, the electronic components 131A to 131D are mounted on the printed circuit board 130 on which the cream solder is printed by the chip mounter. Here, the electronic components 131A and 131B are components to be shielded.

Next, as shown in FIG. 5B, shield frames 120A and 120B for individually enclosing the electronic components 131A and 131B are mounted on the upper surface of the printed circuit board 130, and reflow is performed. The components 131A to 131D and the shield frames 120A and 120B are soldered to the printed circuit board 130 at the same time.
Finally, as shown in FIG. 5C, the shield structures 110A and 110B are covered with the shield frames 120A and 120B to form a shield structure.

  The shield covers 110A and 110B are formed of a top plate for covering the enclosed space of the shield frame and a plate piece suspended from the outer edge of the top plate to cover the upper part of the side wall of the shield frame. By covering these shield covers 110A and 110B on the shield frames 120A and 120B, the electronic components 131A and 131B surrounded by the shield frames 120A and 120B can be individually shielded.

JP 2007-95739 A

Since the technique shown above shields every electronic component to be shielded, it takes time and cost in the assembly process.
In recent years, cost reduction has been demanded in the assembly process of the shield structure. Therefore, it is conceivable to enclose a plurality of electronic components to be shielded by a single shield structure.

When a plurality of electronic components are to be shielded with a single shield structure, the shield frame surrounding the plurality of electronic components is larger than the conventional one. Hereinafter, for convenience of explanation, a shield frame surrounding a plurality of electronic components is referred to as a large shield frame, and a conventional shield frame is referred to as a small shield frame.
Therefore, when soldering a large shield frame, there is a possibility that the amount of cream solder as in the conventional case is not sufficiently bonded. Because the large shield frame is larger than the small shield frame, even if the processing accuracy is the same, the distortion of the large shield frame is larger than the distortion of the small shield frame, ensuring flatness. This is because it becomes difficult.

  Therefore, in order to perform sufficient adhesion, it is conceivable to increase the amount of cream solder from the conventional amount. However, when the amount of cream solder is increased, a phenomenon occurs in which the cream solder adheres to the upper portion of the outer wall surface of the side wall of the large shield frame as compared with the conventional case. This phenomenon is particularly noticeable at the corners of the shield frame. Therefore, if you try to cover the shield cover on the soldered large shield frame, the cream solder adhered to the outer wall surface will not interfere with the plate of the seal cover, and the shield cover must be securely placed on the shield frame. Can not be. That is, the enclosed electronic component cannot be reliably shielded.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a shield structure and an electronic apparatus that can reliably shield one or more enclosed electronic components even if the amount of the adhesive that bonds the shield frame is increased. And

  In order to achieve the above object, the present invention provides a shield structure for shielding an electronic component disposed on a printed circuit board, wherein the electronic component is brazed onto the printed circuit board while surrounding the electronic component. A shield frame bonded by an agent and a shield top plate covering an upper portion of the shield frame, the shield top plate having a plate piece suspended from the outer edge thereof, and the plate piece Are omitted at the corners of the top plate corresponding to the corners of the shield frame.

  According to this configuration, in the shield structure, the plate piece suspended from the outer edge of the shield top plate is omitted at the top plate corner corresponding to the corner portion of the shield frame. Thereby, in each corner part of the frame for shielding, even if the adhesive for brazing is applied to the upper part than the part different from these corner parts, it will be applied to each corner part. Since the contact adhesive and the plate of the shield top plate do not interfere with each other, the shield top plate can be reliably covered with the shield frame. Therefore, the enclosed electronic component can be reliably shielded.

2 is an exploded perspective view of a shield structure 1. FIG. (A) is a perspective view of the shield structure 1, (b) is a sectional view in the direction perpendicular to X-X ′, and (c) is an enlarged view of a portion B shown in (b). It is an enlarged view of the A section shown in FIG. It is a figure which shows the modification of the shape of the shield cover in a corner part. It is a figure which shows an example of the assembly process of the conventional shield structure.

1. DESCRIPTION OF EXEMPLARY EMBODIMENTS First Embodiment Hereinafter, an embodiment of a shield structure according to the present invention will be described with reference to the drawings. In this embodiment, the case where the shield structure is applied to a mobile phone as an example of the electronic apparatus of the present invention will be described.
1.1 Configuration FIG. 1 is an exploded perspective view of a shield structure 1 according to the present invention.

As shown in FIG. 1, the shield structure 1 includes a printed circuit board 30, a shield frame 20, and a shield cover 10.
(Printed circuit board 30)
The printed circuit board 30 is a circuit board mounted on a mobile phone, and is mounted with components, circuits, memory, and the like for realizing the functions of the mobile phone. In the present embodiment, components, circuits, memories, etc. are collectively referred to as electronic components. For example, the electronic components 31A to 31I shown in FIG. 1 correspond to components, circuits, memories, and the like for realizing the functions of the mobile phone.

  The electronic components 31 </ b> A to 31 </ b> F generate noise due to their own operation, or the operation is affected by noise generated by other electronic components. For example, the electronic components 31 </ b> A to 31 </ b> F are a transmission / reception wireless circuit that transmits and receives a modulated wireless signal, a basic LSI (large-scale integrated circuit), a memory, a DC / DC converter, and the like. Here, the basic LSI is a circuit for realizing a basic function of the mobile phone. This basic LSI includes a CPU, an audio circuit, a modulation / demodulation radio circuit that modulates a signal to be transmitted and a received signal, a key operation controller, a controller for USB connection, a controller for charging, and the like. It is.

The electronic components 31G to 31I generate noise or have no influence on the operation even when receiving noise generated by other electronic components. Examples of the electronic components 31G to 31I include a matching circuit that performs matching in an antenna and a light emitting diode.
(Shield frame 20)
The shield frame 20 is made of a foil, and among the electronic components 31A to 31I mounted on the printed circuit board 30, the side walls 23A to 23G surrounding the plurality of electronic components 31A to 31F that need to be shielded, and the electronic components 31A to 31F. It is formed from partition walls 22A to 22E for isolating each. Moreover, the height of the shield frame 20 is 1.5 mm, for example.

The shield frame 20 performs die cutting of a shape in which a portion where the side walls 23A to 23G are to be formed and a portion where the partition walls 22A to 22E are to be formed on the same plane from the plate-like western foil, Then, it produces | generates by bending the location corresponding in order to form side wall 23A-23G and partition wall 22A-22E.
Further, in the shield frame 20, corners 21A to 21F having an angle on the foil plate of 90 degrees are formed.

By forming the partition walls 22A to 22E for isolating the electronic components 31A to 31F, the shield frame 20 causes the electronic components 31A to 31F to affect other electronic components in the shield frame 20 with noise. It is possible not to be influenced by other electronic components.
In the present embodiment, in each of the two sides forming each of the corners 21A to 21F, a portion extending 3 mm from the corner in the side direction from the corner to the other end is referred to as a corner portion.

(Shield cover 10)
The shield cover 10 is made of a foil like the shield frame 20, and is fitted to the shield frame 20 to cover the upper portion of the shield frame 20, that is, the enclosed space.
The shield cover 10 is formed of a top plate 13 that covers the enclosed space, and plate pieces 11A to 11L that are suspended from the top plate 13 so as to contact the outer wall surfaces of the side walls 23A to 23G of the shield frame 20. Has been. A contact method between the outer wall surfaces of the side walls 23A to 23G of the shield frame 20 and the plate pieces 11A to 11L will be described later.

  In the present embodiment, each of the plate pieces 11A, 11D, 11E, 11H, and 11J close to the corners 12F, 12A, 12D, and 12E having an angle on the western foil plate of 90 degrees is from the end near the corner to the corner. The distance is about 3 to 5 mm. Further, the height of each of the plate pieces 11A to 11L is about 0.25 mm lower than the height of the shield frame 20, that is, 1.25 mm.

  As shown in FIG. 1, these plate pieces 11 </ b> A to 11 </ b> L are suspended from the edges of other portions excluding the corner portions on the top plate corresponding to the positions of the corner portions on the shield frame 20. In other words, on the top plate 13, that is, at each corner portion of the shield cover 10, plate pieces for contacting the outer wall surfaces of the side walls 23 </ b> A to 23 </ b> G of the shield frame 20 are omitted.

The shield cover 10, like the shield frame 20, performs die cutting of a shape in which the top plate 13 and the plate pieces 11 </ b> A to 11 </ b> L are formed on the same plane from a plate-like western foil, and then the plate pieces It is generated by bending a corresponding portion to form 11A to 11L.
1.2 Assembly FIG. 2A is a perspective view of the shield structure 1 after the shield cover 10, the shield frame 20, and the printed board 30 shown in FIG. 1 are assembled.

Hereinafter, a procedure for assembling the shield cover 10, the shield frame 20, and the printed board 30 will be described.
The assembly procedure is the same as that of the prior art.
First, cream solder is printed on the upper surface of the printed circuit board 30 using a metal mask. Next, the electronic components 31A to 31I are mounted on the printed circuit board 30 on which the cream solder is printed by the chip mounter. Further, the shield frame 20 is mounted on the printed circuit board 30 and reflowed to solder the electronic components 31A to 31I and the shield frame 20 to the printed circuit board 30 simultaneously.

Among the procedures so far, the point different from the conventional one is the amount of cream solder when soldering the shield frame 20 onto the printed circuit board 30, particularly the amount of cream solder in the corner portion.
Since the shield frame 20 of the present embodiment surrounds a plurality of electronic components, it is larger than the conventional shield frame that surrounds one electronic component. For this reason, the distortion of the shield frame 20 is larger than that of the conventional shield frame. Therefore, when soldering is performed with the conventional amount of cream solder, soldering is not performed at the corner portion, that is, the corner portion is not bonded to the printed circuit board 30, and a gap is formed between the corner portion and the printed circuit board 30. It will occur.

After the electronic components 31 </ b> A to 31 </ b> I and the shield frame 20 are soldered to the printed circuit board 30, the shield cover 10 is fitted over the shield frame 20.
Here, when the shield cover 10 is fitted to the shield frame 20, it is necessary to contact each plate piece and the outer wall surface of the side wall of the shield frame 20. This is because the shield structure 1 serves as a shield by covering the space surrounded by the shield frame 20.

Therefore, FIG. 2B is a cross-sectional view taken along the line XX ′ in the shield structure 1 after assembly, and the state where the plate piece 11C and the outer wall surface of the side wall 23A of the shield frame 20 are joined, and the plate The state which the piece 11H and the outer wall surface of the side wall 23F of the shield frame 20 have joined is shown.
Here, a specific method for joining the plate piece 11C and the outer wall surface of the side wall 23A of the shield frame 20 will be described with reference to FIG.

FIG.2 (c) is an enlarged view of the B section in FIG.2 (b).
The plate piece 11C has a hemispherical protrusion 14 on the inner surface.
Further, the outer wall surface of the side wall 23 </ b> A has a hemispherical concave portion 24 at a position located on the protrusion 14.
At the time of assembly, the protrusion 14 is fitted into the recess 24 so as to cover and conceal the space surrounded by the shield frame 20 and to join each plate piece to the outer wall surface of the side wall of the shield frame 20.

  Here, the joining of the shield cover 10 and the shield frame 20 has been mainly described. For this reason, in FIGS. 2A to 2C used for the description, the application of cream solder used for bonding the printed circuit board 30 to the electronic components 31G to 31I and the shield frame 20 is not shown. Actually, since the printed circuit board 30, the electronic components 31G to 31I, and the shield frame 20 are bonded with cream solder, the outer wall surfaces of the side walls 23A to 23G of the shield frame 20 and the side surfaces of the electronic components 31G to 31I are used. Is covered with cream solder. In particular, the cream solder used for bonding the printed circuit board 30 and the shield frame 20 is attached to the outer wall surfaces of the side walls 23A to 23G of the shield frame 20 so as not to interfere with the plate pieces 11A to 11L of the shield cover 10. .

The state of adhesion of cream solder in the adhesion between the printed circuit board 30 and each corner will be described later.
1.3 Effect of Shield Structure 1 FIG. 3 is an enlarged view of a portion A in FIG. 2A, and shows a state in which the cream solder 40 is attached to the corner portion of the corner 21 </ b> A of the shield frame 20.

  As described above, the amount of the cream solder 40 in the corner portion of the corner 21A is different from the corner portions of the corners 21A to 21F, for example, the amount of the cream solder in the vicinity of the center of the side wall (hereinafter referred to as the central portion). More printed. Therefore, as shown in FIG. 3, the swell of the cream solder 40 due to the surface tension at the corner portion (the amount deposited on the upper portion) is larger than the swell of the cream solder at the central portion.

Therefore, as in the present embodiment, in the shield cover 10, the plate pieces are not provided at the locations located at the respective corner portions, so that the cream solder swelled at the respective corner portions of the shield frame 20 and the shield The shield structure can be configured without interference with the cover 10.
Moreover, non-adhesion due to distortion of the shield frame 20 at the time of reflow can be prevented by increasing the amount of cream solder at each corner portion as compared with other portions.

Moreover, since the strength of adhesion to the shield frame is increased by increasing the amount of cream solder in each corner portion, the durability of impact and the static load durability are improved.
1.4 Modifications Although described above based on the embodiment, the present invention is not limited to the above embodiment. For example, the following modifications can be considered.

(1) In the said embodiment, you may provide a notch in the location located in a corner part.
For example, the corner 12A may be cut off as shown in FIG. Specifically, in the two sides forming the corner 12A, a triangle formed by connecting one point (first point) of one side to one point (second point) of the other side (see a two-dot chain line). cut out. In this case, the first point and the second point on each side are determined from the corner 12A so that a gap does not occur between the shield frame 20 and the shield cover 10 after cutting.

Thereby, even when the cream solder adheres to the upper surface of the side wall, the shield structure can be configured without interference between the cream solder and the shield cover 10.
In addition, although the shape to cut out was made into the triangle, it is not limited to this.
The shape to be cut out may be another shape. For example, a fan shape or a rectangular shape may be used. In short, the shape to be cut may be such that no gap is generated between the shield frame 20 and the shield cover 10 after cutting.

(2) In the above embodiment, each of the plate pieces 11A, 11D, 11E, 11H, and 11J close to the corners 12F, 12A, 12D, and 12E is formed with the distance from the corner to the end near the corner being about 3 to 5 mm. However, it is not limited to this.
The distance from the corner to the corner end may be changed according to the amount of cream solder to be printed.

(3) In the above embodiment, cream solder is used for bonding the printed circuit board 30, the electronic components 31A to 31I and the shield frame 20, but the present invention is not limited to this.
Any printed circuit board 30 can be used as long as it can bond the electronic components 31A to 31I and the shield frame 20 by brazing.
(4) In the above embodiment, a plurality of electronic components are surrounded by the shield frame 20, but the present invention is not limited to this. There may be one electronic component.

(5) Although the four plate pieces 11A, 11B, 11C, and 11D are formed on the edge that forms between the corner 12A and the corner 12F among the edges of the top plate 13 in the above embodiment, the invention is not limited to this. Only one plate piece may be provided at the edge that forms between the corner 12A and the corner 12F.
Similarly, only one plate piece may be provided on the edge of the top plate 13 at the edge forming the corner 12A to the corner 12F and the edge forming the corner 12E to the corner 12D.

(6) In the above embodiment, the corner portions for the corners 21A to 21F of the shield frame 20 are portions extending 3 mm from the corner, but the present invention is not limited to this.
That is, the length in the side direction from the corner toward the other end is not limited to the above 3 mm, and may be any other appropriate length such as 1 mm, 2 mm, or 4 mm.

  In addition, the length to which each corner is used as the corner portion is not necessarily the same in each corner, but may be any length that can be different in each corner. For example, when the shield frame 20 is bonded to the printed circuit board 30, the corner portion may be a portion where the cream solder adheres from the corner to a location where the cream solder adheres to a position lower than 0.25 mm from the lower portion. Good.

Moreover, the position where the board piece close | similar to corner 12F, 12A, 12D, 12E is formed is changed according to the definition of the corner part mentioned above.
(7) In the above embodiment, the corners 12A to 12F and the corners 21A to 21F are described as being 90 degrees, but the present invention is not limited to this.
The angle of the corner may be any angle that allows the surface tension to occur at the corner when the angle of the sheet is 180 degrees or less.

(8) In the above embodiment, the shield cover 10 and the shield frame 20 are made of foil, but the present invention is not limited to this. Any material can be used as long as it can shield electronic parts.
(9) The shape surrounding one or more electronic components is not limited to the shape shown in the above embodiment.

The shape surrounding one or a plurality of electronic components may be a polygonal shape in plan view.
(10) The above embodiments and modifications may be combined.
(11) The electronic device on which the shield structure 1 shown in the above embodiment is mounted is not limited to a mobile phone. It may be an arbitrary electronic device such as a PDA (Personal Digital Assistant), an electronic dictionary, or a personal computer.

(12) The shield frame in the present invention corresponds to the shield frame 20 in the above embodiment.
The shield top plate in the present invention corresponds to the shield cover 10 in the above embodiment.
1.5 Summary (1) The present invention is a shield structure for shielding an electronic component disposed on a printed circuit board, and brazes the adhesive on the printed circuit board in a state of surrounding the electronic component. And a shield top plate covering an upper part of the shield frame, the shield top plate having a plate piece suspended from the outer edge, the plate piece Further, it is characterized in that it is cut off at the corner of the top plate corresponding to the corner of the shield frame.

  According to this configuration, in the shield structure, the plate piece suspended from the outer edge of the shield top plate is omitted at the top plate corner corresponding to the corner portion of the shield frame. Thereby, in each corner part of the frame for shielding, even if the adhesive for brazing is applied to the upper part than the part different from these corner parts, it will be applied to each corner part. Since the contact adhesive and the plate of the shield top plate do not interfere with each other, the shield top plate can be reliably covered with the shield frame. Therefore, the enclosed electronic component can be reliably shielded.

(2) Here, the shield frame may have a partition wall that isolates the shield frame.
According to this configuration, the shield frame of the shield structure has the partition wall that isolates the shield frame. As a result, when the shield structure surrounds a plurality of electronic components, each of the electronic components does not affect other electronic components in the shielding frame, or is not affected by other electronic components. Can be.

(3) Here, the shield top plate may be further omitted at the corner of the top plate.
According to this structure, the shield structure is brazed to the top plate corner of the shield top plate even when the brazing adhesive is applied to the upper surface of the corner of the shield frame. Since there is no interference with the adhesive for the shield, the shield top plate can be reliably put on the shield frame. Therefore, the enclosed electronic component can be reliably shielded.

(4) Moreover, this invention is an electronic device, Comprising: The shield structure in any one of said (1) to (3) is provided, It is characterized by the above-mentioned.
According to this configuration, the shield structure reliably shields the electronic component without causing interference between the top plate corner of the shield top plate and the brazing adhesive. No malfunction will occur.

  INDUSTRIAL APPLICABILITY The present invention is useful for a shield structure and an electronic device including the shield structure when the amount of the brazing adhesive for bonding the shield frame and the printed board is increased.

DESCRIPTION OF SYMBOLS 1 Shield structure 10 Shield cover 11A-11L Board piece 12A-12F Corner 13 Top plate 20 Shield frame 21A-21F Corner 22A-22E Partition wall 23A-23G Side wall 30 Printed circuit board 31A-31I Electronic component

Claims (4)

A shield structure for shielding electronic components disposed on a printed circuit board,
In a state of surrounding the electronic component, a shield frame bonded to the printed circuit board by a brazing adhesive;
A shielding top plate covering the upper part of the shielding frame,
The shield top plate has a plate piece suspended from its outer edge,
The said board piece is missing in the top plate corner | angular part corresponded to the corner part of the said frame for shielding. The shield structure characterized by the above-mentioned. The shielding frame is
The shield structure according to claim 1, further comprising a partition wall that isolates the shield frame. The shield structure according to claim 1, wherein the top plate for shielding is further removed at the corner of the top plate.   An electronic apparatus comprising the shield structure according to any one of claims 1 to 3.

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