JP2002094410A - Antenna switch module equipped with saw filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an antenna switch module which can be further reduced in height as compared to the conventional modules and easily mounted with a cap on its top. SOLUTION: A high-frequency antenna switch module 1 is composed of a multilayer board 10, diodes D1 to D4 mounted on the board 10, at least a high- frequency SW1 (SW2) composed of inductors and capacitors built in the board 10, at least a low-pass filter LPF1 (LPF2) composed of inductors and capacitors built in the board 10, a SAW filter SAW1 (SAW2) mounted on the board 10, and a cap 7. An opening 6 is provided to the cap 7 of the high-frequency antenna switch 1, with which the antenna switch 1 can be reduced in height, and a time required for putting the cap 7 on the top of the board 10 can be shortened, to enable reducing of the antenna switch price.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antenna switch module having a SAW filter used for a mobile communication device, for example, an automobile telephone, a portable telephone and the like.

[0002]

2. Description of the Related Art It is expected that a mobile communication device equipped with an antenna switch module will be further downsized while further improving its function in order to achieve further miniaturization of the mounted antenna switch module. Becomes indispensable.

For example, as a conventional antenna switch module, Japanese Unexamined Patent Application Publication No. 7-99420 discloses that a SAW filter and other active and passive elements are mounted on a multilayer substrate, and these elements are collectively made of metal. An antenna switch module hermetically sealed with one cap is disclosed.

[0004]

In a conventional antenna switch module, a SAW filter, a passive element, and an active element mounted on a multilayer substrate are collectively covered with a metal cap. The height depends on the height of the SAW filter, which is the largest electric element among the elements mounted on the multilayer substrate, and the higher the height of the SAW filter, the higher the height of the cap itself. For this reason, in order to reduce the size of the entire antenna switch module, it is necessary to reduce the size of the SAW filter itself. It was difficult.

On the other hand, in the antenna switch module, each electric element is mounted at a predetermined position on the multilayer substrate, and after confirming the electrical connection between the wiring formed on the multilayer substrate and each electric element, the cap is closed. It has been manufactured by covering the multilayer substrate and bonding and sealing the cap by reflow.

However, in the process of attaching the cap to the multilayer board, the antenna switch module itself is a very small part, so that the operation of attaching the cap is very difficult and a great deal of time is required for the operation. There is also a problem that the manufacturing cost is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an antenna switch module which is smaller in size, especially lower in height, and less expensive to manufacture.

[0008]

Means for Solving the Problems and Effects of the Invention In order to achieve the above object, an antenna switch module according to the present invention comprises a multilayer substrate having a plurality of dielectric layers laminated, and a multilayer substrate mounted on the multilayer substrate. A diode, at least one high-frequency switch including an inductor and a capacitor built in the multilayer substrate, a filter circuit built in the multilayer substrate and connected to the high-frequency switch, and the multilayer circuit connected to the high-frequency switch. A high-frequency antenna switch module including a SAW filter mounted on a substrate and a cap attached so as to cover the multilayer substrate, wherein an opening is provided in the cap, and the opening is provided in the opening. Is characterized in that the SAW filter is inserted.

It is preferable that the antenna switch module of the present invention is provided with a concave portion for mounting the SAW filter on the multilayer substrate.

In the antenna switch module of the present invention, it is preferable that an inductor and a capacitor constituting a branching circuit are built in the multilayer substrate.

Further, in the antenna switch module of the present invention, it is preferable to use a low-temperature fired ceramic substrate as the multilayer substrate.

According to the antenna switch module of the present invention, since the cap is provided with an opening as a guide when the cap is mounted on the multilayer substrate, the cap mounting operation is facilitated, and the conventional antenna switch module is provided. Compared with the module, the cap mounting operation time is shorter, the manufacturing time is shortened, and the manufacturing cost is reduced.

[0013] In addition, by inserting the SAW filter into the opening, the height of the cap itself and, consequently, the overall height of the antenna switch module can be reduced by at least the thickness of the member forming the cap. Become.
The SAW filter used in the present invention desirably has a configuration in which a surface acoustic wave element is packaged. In such a configuration, even if the cap has an opening, the airtightness of the SAW filter is not impaired.

For example, in the conventional antenna switch module, if the height is the lowest, a cap formed at a height that abuts a SAW filter (packaged with a surface acoustic wave element) mounted on a multi-layer substrate is multi-layered. This is a case where it is attached to a substrate. However, according to the antenna switch module of the present invention, the height can be reduced by the thickness of the member forming the cap as compared with the above-described case of the lowest height.

However, in practice, since there is a height tolerance of the SAW filter and a tolerance of the height of the cap, the cap and the SAW filter are prevented from coming into contact with the SAW filter so as to prevent problems such as poor floating of the cap. Since a gap of at least about 0.1 mm is formed between them, according to the antenna switch module of the present invention, it is expected that the height of the cap forming member itself is reduced by the thickness or more.

Furthermore, even when the size of the SAW filter itself, especially the height, is increased, since the concave portion is provided in the multilayer substrate, the height of the cap is increased even if the SAW filter itself is increased. It is not necessary, that is, the height of the antenna switch module itself can be reduced.

Further, a capacitor and an inductor for constituting a demultiplexing circuit for demultiplexing a signal to a plurality of transmission / reception systems are incorporated by printing in a predetermined pattern on a plurality of dielectric layers forming a multilayer substrate. Therefore, the overall size of the antenna switch module of the present invention is smaller than that in which the capacitor chip and the inductor chip are mounted,
It is possible to cope with a plurality of transmission / reception systems having different pass bands, and higher performance can be expected as compared with the related art.

In addition, according to the antenna switch module of the present invention, impedance matching of each electronic element component such as a high-frequency switch, a filter circuit, a demultiplexing circuit, and a SAW filter can be performed in the module. Since it is not necessary to newly provide an impedance matching circuit between element parts and the number of parts is smaller than in the conventional case, it is possible to reduce the cost and further reduce the size of the entire antenna switch module.

Further, since a low-temperature fired ceramic substrate is used as the multilayer substrate, a plurality of dielectric layers and electrodes forming inductors and capacitors on the dielectric layers can be integrally fired. Therefore, the manufacturing process can be shortened, and the cost can be further reduced.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a block diagram of the antenna switch module according to the present invention, and FIG. 4 is a circuit diagram thereof. The antenna switch module 1 includes a diplexer DP, high-frequency switches SW1 and SW2, low-pass filters LPF1 and LPF2 as low-pass filters, and S as a band-pass filter.
It is composed of AW filters SAW1 and SAW2.

The diplexer DP has a role of combining TX1 and TX2 transmission signals having different frequencies when transmitting, and distributing RX1 and RX2 reception signals having different frequencies at the time of reception. The diplexer DP includes capacitors C1D, C2D, C4DA, C4DB, C5D,
It is composed of inductors L1D and L5.

The high-frequency switch SW1 (SW2) transmits /
Diodes D1, D2 (D
3, D4), inductors L1, L2 (L3, L4), capacitors C1 to C5 (C6 to C10), and a resistor R1 (R
2) and control power supplies Vc11 and Vc12 (Vc21, Vc
c22).

The low-pass filter LPF1 (LPF2), which is a low-pass filter, includes capacitors 1C12 and 1C3.
4, 1C56 (2C12, 2C34, 2C56) and an inductor 1L1 (2L1) are connected between the high-frequency switch SW1 (SW2) and the transmitting unit TX1 (TX2).

[0025]

Embodiment 1 FIG. 1 shows a sectional view of an embodiment of an antenna switch module according to the present invention.

The multilayer substrate 10 is a low-temperature fired ceramic substrate that can be fired at 780 ° C. to 860 ° C. and mainly contains barium oxide, aluminum oxide, silica and the like. The multilayer substrate 10 is formed by sequentially stacking 14 dielectric layers from above.

As the low-temperature firing ceramic used for the multilayer substrate, other than a material mainly containing barium oxide, aluminum oxide, silica, etc., a material mainly containing barium oxide, strontium oxide, silica, etc., and calcium zirconium oxide And a material mainly composed of glass.

The inductors L1 and L2 (L3 and L4) and the capacitors C1 to C5 (C6 to C10) constituting the high-frequency switch SW1 (SW2) are formed by printing a conductive paste on the surface of each dielectric layer constituting the multilayer substrate. Then, a desired pattern electrode is formed, these are appropriately laminated, and formed by integrally firing.

As the conductive paste, there is a paste mainly composed of copper other than a paste mainly composed of silver. The use of a paste mainly composed of copper has advantages of low resistance, no migration, and low material cost.

The diodes D1, D2 (D3, D4) and the resistor R, which constitute the high-frequency switch SW1 (SW2),
1 (R2) is mounted at a predetermined position on the surface of the multilayer substrate via solder, and is electrically connected to the inductor and the capacitor.

The low-pass filter LPF1 (LPF2), which is a low-pass filter, is similar to the high-frequency switch circuit.
The inductor 1L1 (2
L1) and the capacitors 1C12, 1C34, 1C5
6 (2C12, 2C34, 2C56) are formed by printing a conductive paste on the surfaces of the plurality of dielectric layers, forming desired pattern electrodes, appropriately laminating them, and integrally firing them. Built-in.

In this embodiment, a low-pass filter is used as the filter circuit. However, for example, a band-pass filter may be used.

The demultiplexing circuit DP is configured such that the inductors L1D and L5 and the capacitors C1D, C2D, C4DA, C4DB and C5D which constitute the demultiplexing circuit DP are formed by printing a conductive paste on the surface of a plurality of dielectric layers. A desired pattern electrode is formed, laminated appropriately, and fired integrally, and is built in the multilayer substrate 10.

The SAW filter SAW1 (SAW2)
The surface acoustic wave element is hermetically sealed by a metal case, and electromagnetic shielding is sufficiently performed. The SAW filter SAW1 (SAW2) is covered with a case,
It is mounted on the multilayer substrate via solder bumps, and is connected between the high-frequency switch and the receiver RX1 (RX2).

The cap 7 is formed of a metal member, and has an opening 6 as a guide used for attaching the cap 7 to the multilayer substrate 10. The cap is manufactured by pressing a metal plate having a thickness of 0.1 to 0.12 mm into a concave shape and forming an opening by punching. The cap 7 surrounds the multilayer substrate 10 and the diodes D1 and D2 (D3 and D4) collectively, and the SAW filter SAW1
(SAW2) is attached to the multilayer substrate 10 via an adhesive layer in a state where it is inserted. Therefore, the height is reduced by at least the thickness of the member forming the cap as compared with the conventional antenna switch module.

The cap 7 may be mounted on the multilayer board with the SAW filter SAW1 (SAW2) inserted from the opening 6 protruding. However, according to such a configuration, the antenna switch module is mounted on an automatic mounting machine or the like. When mounting on a printed circuit board, there is a possibility that a suction error of the automatic mounting machine may occur and a problem may occur.
It is desirable that the upper surface of the W filter SAW1 (SAW2) and the outer surface of the cap 7 be arranged at the same height.

When the cap 7 is connected to the ground electrode pattern of the multi-layer substrate via a conductive adhesive layer made of solder, conductive resin, or the like, the cap 7 can sufficiently provide electromagnetic shielding. An antenna switch module having better characteristics can be obtained.

The shape of the opening 6 as a guide is substantially the same as that of the SAW filter SAW1 (SAW2) and is rectangular. Further, the size of the opening is formed to have a gap of about 0.1 to 0.45 mm when the SAW filter SAW1 (SAW2) is inserted into the cap 7, so that the opening is covered by the case. SAW
The filter SAW1 (SAW2) can be easily inserted into the opening 6.

The opening 6 is provided with the SAW filter SA.
Two are separately formed corresponding to W1 and SAW2.
However, it is not always necessary to provide one opening for one SAW filter. When a plurality of SAW filters are collectively mounted on a multilayer substrate, a plurality of SAW filters can be inserted at a time. An opening may be formed in a shape and a size.

The shape of the opening 6 is not limited to a square, but may be any shape such as a circle, an ellipse, or a triangle into which a SAW filter can be inserted.

In the reflow process for attaching the cap to the multilayer substrate, the cap 7 and the SAW
Since a gap is formed between the filter and the filter SAW1 (SAW2), there is no possibility that the internal pressure will increase even if the air in the cap 7 expands as the temperature rises, and the cap 7 will blow off. There is no fear.

[0042]

Embodiment 2 FIG. 2 is a sectional view showing the configuration of a second embodiment of the antenna switch module 1 according to the present invention. In the first embodiment, the flat type multilayer substrate 10 is used. However, in the second embodiment, the size of the SAW filter SAW1 (SAW2), particularly, the height is high, and the overall height of the antenna switch module 1 is 1.8 mm. In the case where the number of the SAW filters SAW1 (SAW2) was exceeded, a multilayer substrate 11 having a concave portion 8 in the mounting portion of the SAW filter SAW1 (SAW2) was used. In the case of such a configuration, the same effect as in the first embodiment can be obtained.

In the above embodiment, a dual band type antenna switch module in which a plurality of SAW filters and diodes are mounted on a multilayer substrate has been described.
The present invention is not limited to such a case, and one S
The same effects as those described above can be obtained for a single-band antenna switch module in which an AW filter and a diode are mounted on a multilayer substrate.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of an antenna switch module according to the present invention.

FIG. 2 is a sectional view of another embodiment of the antenna switch module according to the present invention.

FIG. 3 is a block diagram of an antenna switch module according to the present invention.

FIG. 4 is a circuit diagram of the antenna switch module according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Antenna switch module 6 Opening 7 Cap 8 Depression 10 Multilayer substrate 11 Multilayer substrate with depression SAW1, SAW2 SAW filter D1, D2, D3, D4 Diode SW1, SW2 High frequency switch LPF1, LPF2 Low pass filter DP Demultiplexer C1-C10, 1C12-2C56 Capacitor L1-L10, 1L1, 2L1 Inductor

Claims (4)

[Claims] A multi-layer substrate formed by laminating a plurality of dielectric layers, a diode mounted on the multi-layer substrate, and at least one high-frequency switch including an inductor and a capacitor built in the multi-layer substrate; A filter circuit built in the multilayer substrate and connected to the high-frequency switch; a SAW filter connected to the high-frequency switch and mounted on the multilayer substrate; and a cap mounted to cover the multilayer substrate. A high frequency antenna switch module, wherein an opening is provided in the cap, and the SAW filter is inserted into the opening. 2. The high frequency antenna switch module according to claim 1, wherein the multilayer substrate is provided with a concave portion, and the concave portion is provided with the SAW filter. 3. The high frequency antenna switch module according to claim 1, wherein a branching circuit comprising an inductor and a capacitor and connected to the high frequency switch is built in the multilayer substrate. . 4. A low-temperature fired ceramic substrate is used as said multilayer substrate.
The high frequency antenna switch module according to any one of the above.