JP2785753B2 - High frequency shield structure and method of manufacturing printed board used for high frequency shield structure - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-density high-frequency shield structure used for a radio communication device and the like, and a method of manufacturing a printed board used for the high-frequency shield structure.

[0002]

2. Description of the Related Art Conventionally, as a mounting structure of a high-frequency circuit used in a radio communication device of this kind, Japanese Patent Application Laid-Open No.
Some of them have been proposed in Japanese Patent Application Laid-Open No. 200, Japanese Patent Application Laid-Open No. 5-251584, and the like. For example, JP-A 1-2252
As shown in FIG. 10 and FIG. 11, a mounting structure proposed in Japanese Patent Publication No. 00 is a printed board 82 on which various electric / electronic components 81 are mounted, and a front cover mounted on the front side of the printed board 81. 83, a shield plate 84 and a back cover 85 mounted on the back side of the printed board 81 are fixed through by screws 86. Here, the front cover 83 is formed as a housing of the unit, and houses the electric / electronic components 81 of the printed board 82.

[0003]

The above-mentioned conventional mounting structure of a high-frequency circuit is preferable because it is easy to assemble and process. However, since the shielding effect is determined by the contact between the printed board and the cover, the flatness of both the printed board and the cover is necessary, but the contact is sufficient only around the screwed portion. . Therefore, the contact between the printed board and the cover in places where shielding is actually required is insufficient, and the shielding effect is reduced by half, or the parts attached to the cover such as connectors are not sufficiently contacted with the printed board, and high-frequency characteristics are poor. There was a problem that it became worse.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has a simple structure capable of sufficiently exhibiting a shielding effect, and ensuring high contact between a component mounted on a case and a printed board by using a high frequency. It is an object of the present invention to provide a high-frequency shield structure in which characteristics are not deteriorated, and to provide a printed circuit board used for a high-frequency shield structure that can be manufactured extremely simply and at low cost.

[0005]

In order to achieve the above object, a high frequency shield structure according to the present invention comprises a base layer and a base layer.
Through holes drilled in the
The formed copper foil layer and the base layer are partially laminated and partially laminated.
With prepreg layer protruding through through holes
That the printed circuit board electrical and electronic components are mounted, and a front casing mounted on the surface side of the printed circuit board, a back casing mounted on the back side of the printed circuit board, these printed circuit board, the front casing and the back A screw that is integrally fixed through the case, and a plating layer is formed on at least one of the front and back surfaces of the printed board on a protruding portion of the prepreg layer.
Subjected conductive small projection is formed on the printed board integrally, there the small projection a structure in contact with at least one of the front case and back case.

When an RF connector is used as an input / output of a printed board on which the conductive small projections are formed, the small projections are brought into contact with a case near the RF connector.

[0007] the high frequency shield structure when applied to the RF amplifier, the small protrusion of the conductive is formed on the printed circuit board, it is constituted to contact with the case at the emitter vicinity of the transistor of the RF amplifier.

A method of manufacturing a printed board used in a high-frequency shield structure according to claim 1, 2 or 3, wherein a prepreg layer is projected from a copper foil layer on the surface of the printed board. Apply a plating layer to the layer,
It is configured to manufacture a printer plate having the conductive small protrusions.

[0009] A prepreg layer is laminated on the back surface of the base layer of a printed board having through holes, the prepreg layer is projected to the surface through the through holes, and then the base surface is polished to smooth the prepreg layer. The prepreg layer is made to protrude from the surface copper foil layer of the printed board by etching the foil layer.

[0010]

According to the high-frequency shield structure of the present invention having the above-described structure, the small conductive protrusion formed on the printed board surely contacts at least one of the front case and the back case,
A good shielding effect is achieved, and good contact between the parts to be mounted on the case and the printed board is achieved.

[0011] In the high-frequency shield structure of the present invention,
According to the printed circuit board, blind via hole projection
Improves the contact with the case, and the normal SVH method
In the same manner as a printed circuit board
India via hole protrusions can be formed.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a high-frequency shield structure of the present invention and a method of manufacturing a printed board used for the high-frequency shield structure will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of one embodiment of a high-frequency shield structure according to the present invention, FIG. 2 is a plan view of a printed board used in the high-frequency shield structure according to the present invention, and FIG. FIG. 4 shows an enlarged partial cross-sectional view. In FIG. 1, reference numeral 1 denotes a multilayer printed board manufactured by a surface via hole (hereinafter referred to as SVH) method. A front case 2 is provided on the front side of the multilayer printed board 1 and a rear case 3 is provided on the back side. These are integrally fixed by screws 4.

The multilayer printed board 1 has various electric and
An electronic component 5 is mounted. As shown in FIG. 2, the multilayer printed circuit board 1 has a through hole 12 formed in a base layer 11, and a copper foil layer 13 is plated on the entire surface of the base layer 11 and the through hole 12 to form a blind via.
A hole (hereinafter, referred to as BVH) is formed. A prepreg layer 14 is laminated inside the base layer 11, and a part of the prepreg layer 14 projects through the through hole 12 to the surface of the base layer 11.

A plating layer 15 is formed on the protruding portion of the prepreg layer 14 and the copper foil layer 13, and the protruding portion of the prepreg layer 14 is a small projection (BVH projection) 16. As shown in FIG. 3, such small protrusions 16 are regularly formed on the front and back surfaces (not shown) of the multilayer printed circuit board 1 where the electric and electronic components 5 (not shown) are not mounted. They are provided at substantially equal intervals.

In the above-described high-frequency shield structure, when the multilayer printed board 1 is sandwiched between the front case 2 and the back case 3 and fixed with the screws 4, the small projections 16 completely contact the front case 2 and the back case 3. As in the conventional case, the entire surface of the multilayer printed board 1 is brought into contact with the front case 2 and the back case 3 as well as in the vicinity of the screwing. Therefore, it is possible to satisfactorily shield a portion where a shield is required, and to improve the contact of components such as a connector.

Next, a method for producing the multilayer printed board 1 will be described with reference to FIGS. 4 (a), (b), (c), (d) and (e). 4 (a), (b),
(C), (d) and (e) are each a view showing a manufacturing process of a printed board used for the high-frequency shield structure of the present invention. First, as shown in FIG.
The base layer 11 on which the base layer 2 is formed is prepared.
A copper foil layer 13 having a thickness of about 18 μm is plated on the entire surface of the substrate 1 and the through hole 12 to form a BVH.

Next, as shown in FIG. 4B, a prepreg layer 14 is laminated on the back surface of the base layer 11, and the resin of the prepreg layer 14 is made to protrude through the through holes 12 to the surface. As shown in (), the surface of the base layer 11 is polished by several μm to make the protruding portion of the prepreg layer 14 smooth. Then, as shown in FIG. 4D, the copper foil layer 13 on the surface is dissolved by an etchant by 2 to 3 μm to protrude the prepreg layer 14 by 2 to 3 μm, and further, as shown in FIG. Then, a plating layer 15 is applied to the protruding portion of the prepreg layer 14 and the copper foil layer 13 to form conductive small projections 16. Then, two sheets of the above are prepared, and the prepreg layers 14 are bonded to each other to complete the multilayer printed board 1 as shown in FIG.

In order to form a circuit pattern on the base layer 11, FIGS. 4A, 4B, 4C and 4D are used.
4E, the plating layer 1 shown in FIG.
5 is formed by protecting the circuit pattern with a mask or the like so as not to be plated. In FIG. 4E, a plating layer 15 may be formed on the entire surface of the copper foil layer 13 and then a circuit pattern may be formed by etching.

In the above embodiment, two small protrusions 16 having conductive small protrusions 16 formed on only one surface were prepared, and the small protrusions 16 were formed on the front surface and the back surface by overlapping them. Although the multilayer printed board 1 was produced, two base layers may be prepared in advance and laminated so as to sandwich the prepreg layer 14 (other steps are the same as those in the above embodiment). Manufacturing by such a method can save material cost and simplify the manufacturing operation.

An embodiment in which the high-frequency shield structure of the present invention is applied to connection with an RF connector will be described with reference to FIGS. FIG. 5 is a partial cross-sectional view of the high-frequency shield structure, and FIG. 6 is a partial vertical cross-sectional view of the high-frequency shield structure.
In these figures, reference numeral 61 denotes a printed board, on which a small conductive protrusion 62 is formed on the front side and the back side, and a microstrip line 63 is formed on the front side. And this printed board 6
1 is sandwiched between the front case 64 and the back case 65, and is integrally fixed by screws (not shown). Table case 64
An RF connector 66 is attached to the back case 65.

When the RF connector 66 is used as the input / output of the printed board 61, if the connection between the RF connector 66 and the microstrip line 63 is not good, the return loss becomes poor and the high-frequency characteristics become poor. Therefore, since the RF connector 66 is attached to the front case 64 and the back case 65, the connection between the front case 64 and the back case 65 becomes important.

In this embodiment, since the printed board 61 and the back case 65 are in contact with each other via the small protrusion 62 and are sandwiched between the front case 64 and the back case 65, the RF connector 6
6, sufficient contact can be obtained, and good RF characteristics can be obtained.

An embodiment in which the high-frequency shield structure of the present invention is applied to an RF amplifier will be described with reference to FIGS. 7, 8 and 9. 7 is a circuit diagram of the RF amplifier, FIG. 8 is a partial cross-sectional view of the high-frequency shield structure, and FIG. 9 is a partial vertical cross-sectional view of the high-frequency shield structure. In FIG. 7, reference numeral 71 denotes a transistor.
3 and the capacitor 74 and the resistor 75
Is connected. Such a circuit is mounted as shown in FIGS.

In FIGS. 8 and 9, reference numeral 76 denotes a printed board, on which small conductive projections 77 are formed in the vicinity of the place where the transistor 71 is mounted. A case 78 is fixed to the printed board 76 with screws 79. In an RF amplifier operating at such a high frequency, if the ground of the emitter of the transistor 71 is not sufficient, a gain cannot be obtained or abnormal oscillation occurs. However, in this embodiment, since the printed board 76 and the cover 78 are in contact with each other via the small projection 77 arranged near the transistor 71, good grounding can be obtained at high frequencies,
An RF amplifier with good characteristics can be constructed.

[0025]

As described above, the high-frequency shield structure of the present invention has a structure in which a BVH projection is formed on a printed board, and the printed board is sandwiched between the front case and the back case. And a good shielding effect can be obtained, and the contact between the components mounted on the case and the printed board becomes good, so that good high frequency characteristics can be obtained. Also,
The printed board of the present invention can make good contact with the case,
Further, it can be manufactured by the same operation as that manufactured by the normal SVH method, and can be manufactured easily and inexpensively.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of a high-frequency shield structure according to the present invention.

FIG. 2 is a plan view of a printed board used for a high-frequency shield structure according to the present invention.

FIG. 3 is an enlarged partial sectional view of a printed board used for a high-frequency shield structure according to the present invention.

FIG. 4 (a), (b), (c), (d) and (e)
4A to 4C show steps of manufacturing a printed board used in the high-frequency shield structure according to the present invention.

FIG. 5 is a partial cross-sectional view of an embodiment in which the high-frequency shield structure according to the present invention is applied to connection with an RF connector.

FIG. 6 is a partial longitudinal sectional view of an embodiment in which the high-frequency shield structure according to the present invention is applied to connection with an RF connector.

FIG. 7 shows a circuit diagram of an RF amplifier.

FIG. 8 is a partial cross-sectional view of an embodiment in which the high-frequency shield structure according to the present invention is applied to an RF amplifier.

FIG. 9 is a partial longitudinal sectional view of an embodiment in which the high-frequency shield structure according to the present invention is applied to an RF amplifier.

FIG. 10 is an exploded perspective view of a conventional high-frequency shield structure.

FIG. 11 shows a cross-sectional view of a conventional high-frequency shield structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Printed board 2 Front case 3 Back case 4 Screw 5 Electric / electronic component 11 Base layer 12 Through hole 13 Copper foil 14 Prepreg layer 15 Plating layer 16 Small protrusion

Claims (5)

(57) [Claims] 1. A base layer and a hole formed in the base layer.
The through-hole and the copper foil formed in this through-hole
Layer and a part of the base layer,
And a prepreg layer which projects I, and the printed board electrical and electronic components are mounted, and a front casing mounted on the surface side of the printed circuit board, a back casing mounted on the back side of the printed circuit board, These printed boards, having a screw that penetrates the front case and the back case and is integrally fixed, at least one of the front and back surfaces of the printed board
And wherein the electrically conductive small protrusions plated layer on the protruding portions of the prepreg layer is formed integrally with the printed circuit board and the small projection structure in contact with at least one of the front case and back case High frequency shield structure. 2. The high-frequency shield structure according to claim 1, wherein when the RF connector is used as an input / output of the printed board on which the conductive small protrusion is formed, the small protrusion is brought into contact with a case near the RF connector. Wherein said RF shield structure when applied to the RF amplifier, claim a small projection of the conductive is formed on the printed circuit board is contacted with the case at the emitter vicinity of the transistor of the RF amplifier 1 Or the high-frequency shield structure according to 2 . 4. A method of manufacturing a printed board used in a high-frequency shield structure according to claim 1, 2 or 3, wherein a prepreg layer is projected from a surface copper foil layer of the printed board, and thereafter, the prepreg layer has a projecting portion. A method of manufacturing a printed board for use in a high-frequency shield structure, comprising applying a plating layer to a copper foil layer to manufacture a printer board having the conductive small protrusions. 5. A prepreg layer is laminated on a back surface of a base layer of a printed board having a through hole, the prepreg layer is projected to the surface through the through hole, and the base surface is polished to smooth the prepreg layer. 5. The method for manufacturing a printed board used in a high-frequency shield structure according to claim 4 , wherein the prepreg layer is projected from the surface copper foil layer of the printed board by etching the copper foil layer.