JP2003060483A - Surface acoustic wave device and manufacturing method therefor, and communication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an elastic surface wave device which is superior in filter properties and has improved yield, and to provide its manufacturing method and a communication device. SOLUTION: This device is provided with surface acoustic wave filters 5 and 6; an antenna terminal 13, which is a common terminal connected to the elastic surface wave filters 5 and 6; capacitors 7 and 8 for impedance matching of the antenna terminal 13, and a coil 9; a cover material 1, which covers the surface acoustic wave filters 5 and 6, the capacitors 7 and 8, and the coil 9. The cover member 1 is provided with an opening 1a for enabling the coil 9 to be transformed from the outside.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplexer used when transmitting and receiving at the same time using a single antenna, and more particularly to a surface acoustic wave device which is a surface acoustic wave duplexer and a device therefor. The present invention relates to a manufacturing method and a communication device.

[0002]

2. Description of the Related Art With the recent reduction in size and weight of communication devices such as mobile phone terminals, various electronic parts used in communication devices have elasticity that can be made smaller and lighter than conventional dielectric filters. Surface wave filters (hereinafter referred to as SAW filters) have come to be used. Further, in the above electronic parts, a composite part in which peripheral parts such as a plurality of SAW filters, capacitors and coils are put together is being promoted.

For example, in a duplexer (DPX) as an electronic component having a function of distributing a signal input from an antenna to a terminal and a signal output from a terminal to an antenna, there are two components, one for transmission and one for reception. There is known a surface acoustic wave demultiplexer (hereinafter referred to as SAWDPX) in which a capacitor and a coil for impedance matching are added to a SAW filter (JP-A-9-181567).

In this SAWDPX, it is necessary to perform impedance matching between each of the transmitting and receiving SAW filters, but a method using the above-described matching circuit using a capacitor and a coil for the impedance matching (Japanese Patent Laid-Open No. Hei 10-1999) (See FIG. 6 of JP-A-9-181567) or a method using a delay circuit with a delay line is used.

On the other hand, although it is not an example of DPX, an impedance matching coil is formed on a sub-board, laser trimming is performed to adjust the characteristics of the coil, and then the coil is sealed with a metallic lid for magnetic shielding. A method for manufacturing a surface acoustic wave element module is also known (Japanese Patent Laid-Open No. 5-152).
881).

[0006]

However, in the above-mentioned conventional method, the yield of the obtained SAWDPX is deteriorated, which causes a problem of cost increase.

That is, the characteristics of the matching circuit and the delay circuit are unique when they are manufactured, and they do not have a function of adjusting the characteristics after manufacturing. Therefore, conventionally, if a SAWDPX is configured by adding the matching circuit and the delay circuit to a SAW filter having characteristic variations due to processing variations, many SAWDPXs are formed.
Can get the required characteristics, while some SAWDP
In X, there are some that do not meet the required characteristics,
There is a problem that the yield of DPX is lowered and the cost is increased.

Further, in order to reduce the cost of the SAWDPX, it is necessary to eliminate some SAWDPX which does not satisfy the required characteristics to improve the yield, but it is difficult with the conventional method.

As a method for solving this, there is a method called laser trimming described above. However, SAWD
In the case of the PX, in particular, when the counterpart attenuation amount is required, the characteristics change before and after attachment of the metal lid, so that accurate adjustment is difficult in the above example.

In order to solve the above problems, the present invention provides SA
A surface acoustic wave device as a small and inexpensive SAWDPX and a method for manufacturing the same, which has a structure that can be adjusted in a completely assembled state in a WDPX and has no special equipment, and uses the surface acoustic wave device. The purpose of the present invention is to provide a communication device.

[0011]

In order to solve the above problems, a surface acoustic wave device of the present invention includes a plurality of SAW filters and a common terminal in which at least one terminal of each SAW filter is shared. In a surface acoustic wave device having at least one impedance matching passive element connected to a common terminal and a cover for covering the SAW filters and the passive elements, for adjusting the impedance of the passive element with respect to the cover. It is characterized in that an opening is formed.

According to the above structure, since the cover for covering the SAW filters and the passive elements is provided, each component such as each SAW filter can be protected mechanically and electromagnetically, and moreover, by the cover. It can be easily transported,
For example, mounting of a communication device such as a mobile phone on the motherboard can be simplified.

Further, in the above-mentioned structure, since the opening for adjusting the impedance of the passive element is formed in the cover, the passive element can be passed through the opening even after all the above-mentioned constituent members and the cover are attached. Since the impedance can be adjusted, it is possible to avoid the characteristic change caused by attaching the cover after the adjustment without the cover, and it is possible to surely improve the characteristic of the obtained configuration. Therefore, in the above configuration, the characteristics can be improved and the non-defective rate (yield) can be improved.

In the surface acoustic wave device, the passive element is preferably an air core coil. According to the above-mentioned configuration, the coreless coil can deform the wound conductive wire, for example, widen the interval between the adjacent conductive wires, as compared with the cored coil in which the conductive wire is wound around the high magnetic permeability core. Since it is easy, the above adjustment can be simplified.

In order to solve the above problems, a method of manufacturing a surface acoustic wave device according to the present invention includes a plurality of SAW filters,
A common terminal in which at least one terminal of each SAW filter is made common, at least one passive element for impedance matching connected to the common terminal, and each SAW
A method of manufacturing a surface acoustic wave device having a filter and a cover that covers the passive element is characterized in that the impedance of the passive element is adjusted in the cover through an opening formed in the cover.

According to the above method, since the impedance of the passive element is adjusted in the cover through the opening formed in the cover, the characteristic change caused by attaching the cover after the adjustment without the cover is avoided. It is possible to ensure the improvement of the characteristics of the obtained structure. Therefore, in the above method, the characteristics of the obtained surface acoustic wave device can be improved and the non-defective rate (yield) can be improved.

In the above manufacturing method, the coil may be deformed in order to adjust the impedance of the coil as the passive element. According to the above method, as compared with a coil with a core in which a conductive wire is wound around a core having a high magnetic permeability, the air-core coil can deform the wound conductive wire, for example, widen the interval between adjacent conductive wires. Since it is easy, the above adjustment can be simplified.

In order to solve the above problems, the communication device of the present invention is characterized by having any one of the surface acoustic wave devices described above. According to the above configuration, since the surface acoustic wave device having excellent characteristics and improved yield and reduced cost is provided, it is possible to improve the characteristics and reduce the cost.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 shows an embodiment of the present invention.
The following is a description with reference to FIG.

SA as a surface acoustic wave device according to the present invention
An embodiment of the WDPX is shown in FIG. SAWDPX above
As shown in FIGS. 1 (a) and 2, the SAW filter 5 for transmission (Tx) and the SAW filter 5 for transmission (Tx) are formed on the substrate 2 made of glass fiber reinforced epoxy resin (glass epoxy) and having a substantially rectangular plate shape. A SAW filter 6 for reception (Rx) is provided in parallel.

The SAW filters 5 and 6 are provided with a SAW filter section in which a comb-shaped electrode pair or electrode pad is formed on a piezoelectric substrate such as LT (lithium tantalate) or LN (lithium niobate) by photolithography. There is.
Therefore, each of the SAW filters 5 and 6 has a filter function in which the pass band and the outside of the pass band other than that are set by the setting of the comb-shaped electrode pair.

The SAW filters 5 and 6 are respectively SA
It has a substantially square plate-shaped package for accommodating and mounting the W filter portion, which is made of alumina or the like. External terminals for input / output with the outside are formed on the package.

On the substrate 2, the SAW filters 5 and 6 are arranged such that the lateral direction of the SAW filters 5 and 6 is along the longitudinal direction of the substrate 2 and both ends of the SAW filters 5 and 6 in the longitudinal direction. At least one of the surfaces is arranged on the same line.

An antenna terminal 13 is provided at the center of one of the side faces and bottom face of the substrate 2 (opposite to the mounting face of the SAW filters 5 and 6) on each of the short-side end faces of the substrate 2.
One terminal of each SAW filter 5 and 6 (antenna (A
(NT) terminal) so as to be a common terminal.

Input / output terminals 11 for the SAW filter 5 are provided on the side surface and the bottom surface of the substrate 2 on the SAW filter 5 side.
Are arranged. S of the side surface and the bottom surface of the substrate 2
An input / output terminal 12 for the SAW filter 6 is arranged on the AW filter 6 side.

Further, on the substrate 2, the capacitors (passive elements) 7 and 8 and the coil (passive element) 9 for impedance matching at the antenna terminal 13 are provided on the antenna terminal 13 and the SAW filters 5 and 6, respectively. It is implemented between and.

The capacitors 7, 8 and the coil 9 are
It is inserted to achieve matching on the Rx side between the antenna terminal 13 and Rx. Each capacitor 7,
Examples of the multilayer capacitor 8 include a multilayer capacitor formed by interposing a plurality of internal electrodes in a substantially rectangular parallelepiped chip-shaped dielectric ceramic.

Further, although not shown, each S is provided on the substrate 2.
For wiring between the constituent members such as the AW filters 5 and 6,
A wiring pattern made of aluminum foil or copper foil is preferably formed in multiple layers in the thickness direction of the substrate 2.

Each of the capacitors 7 and 8 may be formed by using the above wiring pattern instead of the multilayer capacitor and sandwiching an insulator (dielectric) between the multilayer wiring patterns in the thickness direction of the substrate 2. . Further, when the wiring pattern of the substrate 2 is a single layer, each of the capacitors 7 and 8 is formed by providing a pair of electrodes made of copper or the like with a predetermined gap at positions facing each other (the surface direction of the substrate 2). It may have been done.

Examples of the coil 9 include a conductor wire (conductor) such as a copper wire covered with an insulator such as enamel wound in a cylindrical coil shape. The coil 9 is mounted on the substrate 2 such that the central axis of the coil 9 is substantially parallel to the surface of the substrate 2 and is connected to the wiring pattern. Therefore, the coil 9 is installed such that the distance between the adjacent conductors of the coil 9 can be changed from the outside, that is, the coil 9 can be deformed.

Further, as shown in FIGS. 1A and 1B, the substrate 2 is made of a metal plate so as to cover the SAW filters 5 and 6, the capacitors 7 and 8, and the coil 9. The cover material 1 is provided with a substantially rectangular parallelepiped outer shape. As the material of the cover material 1, it is preferable to have conductivity in order to exert an electromagnetic shielding function, and a conductive plastic plate or the like can be used in addition to the metal plate.

The SAW to which the cover material 1 is attached
When the DPX is mounted on a motherboard of a communication device such as a mobile phone, the DPX is mounted on the motherboard by chucking (absorption of the tip of the tube by suction) from above the SAWDPX (that is, the surface side of the cover material 1). The method of doing is generally used. Therefore, it is preferable that the cover material 1 has a planar shape at the chucking position, for example, the central portion thereof, and further preferably is substantially parallel to the surface of the substrate 2.

In addition, the cover material 1 is provided at a plurality of corners of the substrate 2.
Is mounted on the substrate 2 and the mounting portion 4 is a SAWD
It is connected to the GND of the PX. The mounting section 4
Thus, the cover material 1 is also set to be GND. Therefore, in the SAWDPX, the cover material 1 can strengthen the GND and can have a shielding function against electromagnetic waves from the outside and the inside.

In the cover material 1, an opening 1a for operating and deforming at least a part of the coil 9 from the outside is formed at a position corresponding to the installation portion of the coil 9, that is, in the vicinity of the antenna terminal 13. Has been done.

The opening 1a has such a size that at least a part of the coil 9 can be manipulated and deformed from the outside.
The coil 9 is formed to have a size substantially according to the size of the coil 9 (the size of the cross section including the central axis), and is formed in the peripheral portion of the cover material 1. Therefore, even if the opening 1a is formed in the cover material 1, it is possible to avoid impairing the function of covering and protecting the internal components of the cover material 1, the chucking function, and the shield function.

By providing the opening 1a as described above, after the SAW filters 5, 6 and the capacitors 7, 8 and the coil 9 have been attached to the SAWDPX, the coil 9 is externally passed through the opening 1a. Therefore, the impedance characteristic of the coil 9 can be finely adjusted by deforming the coil 9 with, for example, a minus driver.

The coil 9 described in the present embodiment uses an air-core coil in which the core of the coil 9 is a space. The coil 9 made of an air-core coil has a low loss due to the coil 9, so that a low-loss DPX characteristic can be obtained.
As compared with a coil in which a conductive wire is wound around a core having a high magnetic permeability, the winding of the coil 9 can be easily deformed, so that fine adjustment can be easily performed.

As described above, FIG. 1 schematically shows these, but the actual appearance when the cover material 1 is removed is as shown in FIG. Further, FIG. 3A shows an equivalent circuit showing the connection of these mounted components. Here, the numbers indicating the same parts are the same.

Next, the operation and effect of the above configuration will be described. In the above configuration, the inductance of the coil 9:
When L changes, the DPX characteristic changes accordingly.
When coil 9 with different L is mounted, AN of SAWDPX
5 and 6 show examples in which the pass characteristic of T → Rx changes. The SAWDPX shown here has a pass band on the Tx side of 8
24 to 849 MHz, the pass band on the Rx side is 869
.About.894 MHz.

For changes in L, Tx of DPX → AN
The characteristics of the T characteristic, ANT → Rx characteristic, and isolation characteristic change subtly, but here, the transmission characteristic of the ANT → Rx characteristic with the largest change (in-band loss, VSWR (Voltage Standing Wave Ratio, voltage standing) Wave ratio)) is described. The largest change in the ANT → Rx characteristic is that the coil 9 is the antenna terminal 13 of the SAWDPX.
It is because it is inserted between each ANT terminal of each SAW filter 5 and 6. From FIGS. 5 and 6, by changing the inductance value of the coil 9, the ANT
→ It can be seen that the pass characteristic of the Rx characteristic greatly changes.

On the other hand, the coil 9 is made by winding a conductive wire made of copper or the like a plurality of times. Is changed, for example, by mechanically changing so as to widen the coil 9
Set to a. At this time, since the magnetic flux formed changes before and after the deformation, the inductance value (impedance value) of the coil 9a after the deformation changes with respect to the coil 9 before the deformation. As in this example, when the space between the mutually adjacent conducting wires is widened, the inductance value decreases, and when the space is narrowed, the inductance value increases. In fact, Figure 4
Due to the deformation from (a) to FIG. 4 (b), the inductance value of 1.2 nH or more changes. Therefore, the inductance value is changed by deforming the coil 9,
This change can change the DPX characteristics.

As described above, by deforming the coil 9 after attachment with the cover material 1 attached, D
It can be seen that the PX characteristics can be adjusted. On the other hand, SAW filters are produced in large quantities at once by using the photolithography technology as described above, but due to various factors such as the distribution within the wafer that is the piezoelectric substrate and the change in processing conditions with time. Not all SAW filters can exhibit the same characteristics as each other.

Similarly, the capacitors 7 and 8, the coil 9 and the substrate 2 which form the SAWDPX also have variations. Therefore, some SAWDPXs assembled using these may not satisfy the required characteristics.

For example, the Smith chart shown in FIG. 7 shows the reflection characteristics on the ANT side in ANT → Rx before and after the deformation of the coil 9. Here, in FIG. 7, the center is 50Ω.
It is a Smith chart when, and the closer to the center, the better the matching and the smaller VSWR.

The alternate long and short dash line in the Smith chart above is
ANT in SAWDPX that does not meet the required characteristics
→ Rx passband on ANT side of Rx characteristics (869MHz to 8
It is a reflection characteristic of 94 MHz), and it can be seen that it is deviated from 50Ω. At this time, VSWR was 2.12.

By deforming the coil 9 of this DPX to form the coil 9a with L adjusted, the characteristics could be improved as shown by the thick line in FIG. VSW after improvement
R = 1.88.

In this way, if the cover member 1 is provided with the opening 1a for adjusting the coil 9, the coil 9 after the attachment is mounted.
It is possible to adjust the DPX characteristics by deforming the coil 9 through the opening 1a and adjusting it to the coil 9a without removing the cover material 1 or the cover material 1.

In the above embodiment, the coil 9 is deformed, but a part of the capacitors 7 and 8 shown in FIG. 3 are formed by copper electrodes on the substrate 2 made of glass epoxy. The same effect can be obtained by trimming the copper electrode from the opening 1a of the cover material 1 with a laser.

Furthermore, the impedance matching circuit is not limited to that shown in FIG.
Similar effects can be obtained with a duplexer in which the coils 9 are connected in parallel as shown in FIG. Further, in the above, the example applied to the SAWDPX has been described, but if the electronic component has a passive element such as a coil and a capacitor exposed on the substrate and that covers the passive element, it is an electronic component. , As well as applicable.

Next, a communication device 100 equipped with the surface acoustic wave device according to this embodiment will be described with reference to FIG. The communication device 100 includes an antenna 101, an antenna common part / RFTop filter 102, an amplifier 103, and an R as a receiver side (Rx side) for receiving.
x interstage filter 104, mixer 105, 1stIF filter 106, mixer 107, 2ndIF filter 10
8, 1st + 2nd local synthesizer 111, TC
XO (temperature compensated crystal oscillator)
(Temperature compensated crystal oscillator) 112, divider 113,
It is configured to include a local filter 114. Rx
It is preferable to transmit each balanced signal from the interstage filter 104 to the mixer 105 in order to secure balance, as shown by the double line in FIG.

Further, the communication device 100 uses the antenna 101 as a transceiver side (Tx side) for transmission.
And the antenna common part / RFTop filter 102
And TxIF filter 121, mixer 122, Tx interstage filter 123, amplifier 124, coupler 125, isolator 126, APC (automatic power).
er control (automatic output control) 127.

The surface acoustic wave device according to the present embodiment described above is the same as the Rx interstage filter 104, 1s.
tIF filter 106, TxIF filter 121, Tx
It can be suitably used for the interstage filter 123 and the antenna common part / RFTop filter 102, particularly for the antenna common part / RFTop filter 102.

Therefore, in the above communication device, the surface acoustic wave device used is downsized, the variation in characteristics is suppressed, and the cost is reduced, especially in the GHz band or higher, and the reliability and cost are reduced. It can be achieved.

[0054]

As described above, the surface acoustic wave device and the method of manufacturing the same according to the present invention have a structure in which an opening for adjusting the impedance of the passive element is formed in the cover. Is a method of adjusting inside the cover through the opening.

Therefore, the above configuration and method do not satisfy the required characteristics due to the characteristic variations of the components.
Can be adjusted to a satisfactory characteristic by the deformation of the passive element. At this time, since the cover has an opening,
It is possible to make adjustments with the assembled finished product, and it is possible to make sure adjustments.

The adjustment can also be performed by a simple method of deforming a passive element such as a coil. This allows
This has the effect of contributing to the improvement of the yield rate of the surface acoustic wave device, and eventually to the cost reduction of the surface acoustic wave device.

As described above, the communication device of the present invention has the above-mentioned surface acoustic wave device. Therefore, the above-described configuration has an effect that it is possible to improve the characteristic variation by ensuring the adjustment and reduce the cost by improving the non-defective rate.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a SAWDPX according to an embodiment of the present invention, (a) is an exploded perspective view, and (b) is a perspective view.

FIG. 2 is a plan view of the SAWDPX without a cover material.

3A and 3B are circuit diagrams of an impedance matching circuit in the SAWDPX, where FIG. 3A is a circuit diagram of an embodiment and FIG. 3B is a circuit diagram of a modified example.

FIG. 4 is an explanatory view showing a state where the coil in the SAWDPX is deformed, (a) shows before deformation,
(B) shows after deformation.

FIG. 5 is a graph showing a change in in-band loss with respect to a change in inductance according to a deformation of a coil in the SAWDPX.

FIG. 6 is a graph showing changes in VSWR with respect to changes in inductance according to coil deformation in the SAWDPX.

FIG. 7 is a Smith chart showing changes in DPX characteristics of the SAWDPX before and after deformation of the coil.

FIG. 8 is a block diagram of a main part of a communication device using the SAWDPX.

[Explanation of symbols]

1 cover material 1a opening 5, 6 SAW filter (surface acoustic wave filter) 7, 8 Capacitor (passive element) 9 coil (passive element) 13 Antenna terminal (common terminal)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tatsuro Nagai             2-10-10 Tenjin, Nagaokakyo, Kyoto Stock             Murata Manufacturing Co., Ltd. F term (reference) 5J097 AA12 AA32 AA34 BB15 HB00                       JJ01 LL01

Claims (5)

[Claims] 1. A plurality of surface acoustic wave filters, a common terminal in which at least one terminal of each surface acoustic wave filter is shared, and at least one passive element for impedance matching, which is connected to the common terminal. A surface acoustic wave device having the surface acoustic wave filters and a cover covering the passive element, wherein the cover has an opening for adjusting impedance of the passive element. . 2. The surface acoustic wave device according to claim 1, wherein the passive element is an air-core coil. 3. A plurality of surface acoustic wave filters, a common terminal in which at least one terminal of each surface acoustic wave filter is made common, and at least one passive element for impedance matching, which is connected to the common terminal. In the method of manufacturing a surface acoustic wave device having each of the surface acoustic wave filters and a cover that covers the passive element, the impedance of the passive element is adjusted in the cover via an opening formed in the cover. Method of manufacturing surface acoustic wave device. 4. The method of manufacturing a surface acoustic wave device according to claim 3, wherein the coil is deformed in order to adjust the impedance of the coil as a passive element. 5. A communication device comprising the surface acoustic wave device according to claim 1.