Patent Application
20240171150
This application claims priority to Japanese Application No. 2022-185860, filed Nov. 21, 2022, which are incorporated herein by reference, in their entirety, for any purpose.
The present invention relates to acoustic wave devices.
Mobile communication terminals typified by smartphones are required to correspond to a plurality of high-frequency bands. This has employed a front-end module mounted with a plurality of band-pass filters that allows to pass a communication in a high-frequency band.
As a front-end module, acoustic wave devices such as band-pass filters, duplexers, or quadruplexers are employed.
Patent Document 1 (JP2019-54354) discloses a technique related to an acoustic wave device.
A primary object to be solved by the present invention will be described.
A device chip such as a SAW filter is flip-chip bonded to a wiring substrate in an acoustic wave device such as a band-pass filter or a duplexer.
The resonator structuring the SAW filters forms a hollowed region for mechanical vibration and is sealed by synthetic resin or metal.
Since a resonator of an acoustic wave device generates heat by mechanical vibration or the like, a package structure superior in heat dissipation capability is desired.
In addition, it is desired that the adhesion between a sealing resin member and a wiring substrate is high in order to reduce the infiltration of moisture into the sealed hollowed region.
The sealing resin easily infiltrates between the wiring substrate and the device chip when the metal pattern formed on the outer edge of the wiring substrate is a jagged pattern oriented toward the center. It happens because the sealing resin has liquidity before the sealing process completed.
It is desirable to be considered to prevent coupling phenomenon or the like between the metal pattern which the electric signal of the desired frequency band passes through and the metal pattern which the electric signal of the desired frequency band does not pass through.
Poor heat dissipation may occur the deterioration of the characteristics, the power-resistant life, and the like. Also, poor adhesion between the sealing resin member and the wiring substrate is likely to rust the inside metal, and occurs the deterioration of the characteristics, deterioration in life, or the like. Further, the characteristics deteriorate when coupling phenomenon occurs. In addition, the possibility that the resin comes into contact with the resonator portion would be higher, when a large amount of the sealing resin infiltrates between the wiring substrate and the device chip.
The present invention is devised in view of the above problems. A purpose of the present invention is to provide an acoustic wave device superior in heat dissipation capability and adhesion between a sealing resin member and a wiring substrate, and the acoustic wave device includes excellent characteristics in which coupling between a metal pattern through which an electric signal of a desired frequency band passes and a metal pattern through which an electric signal of a desired frequency band does not pass is unlikely to occur, while an amount of infiltration of a sealing resin between the wiring substrate and a device chip is controlled.
In order to achieve the above object, according to the present invention, an acoustic wave device includes a wiring substrate, a device chip flip-chip bonded on the wiring substrate via a plurality of bumps, a metal pattern formed on an outer edge portion of the wiring substrate, the metal pattern includes an uneven portion or a jagged portion, a plurality of bump pads formed on the wiring substrate comprises an antenna pad, a transmitting pad, a receiving pad and a ground pad, a sealing resin member bonded to both the metal pattern and the wiring substrate, the sealing resin member hermetically seals the device chip, a first region which is a tip direction of the uneven portion or the jagged portion formed to orient toward the outer edge of the wiring substrate, a second region which is the tip direction of the uneven portion or the jagged portion formed to orient toward a center of the wiring substrate, and a surface acoustic wave resonator formed on the device chip and disposed in the vicinity of the first region or the second region.
Embodiments of the present invention will now be described in details hereinafter with reference to the accompanying drawings.
As shown in
In the present embodiment, an example of an acoustic wave device which is a duplexer mounted with the two device chips 5 shown, but it should be understood that, as an application object of the present invention, the acoustic wave device as a band-pass filter in which the one device chip 5 is provided or a quadruplexer in which the four device chips 5 are provided may be used. In addition, a functional element for realizing a duplexer may be formed on the one device chip.
For example, a multilayer substrate made of resin or a plurality of dielectric layers made of low-temperature co-fired ceramic (Low Temperature Co-Fired Ceramics: LTCC) is used for the wiring substrate 3. Further, the wiring substrate 3 has a plurality of external connection terminals 31.
As the device chip 5, a substrate made of, for example, a piezoelectric single crystal such as lithium tantalate, lithium niobate, or quartz, or piezoelectric ceramics can be used.
The device chip 5 may be a substrate in which a piezoelectric substrate and a support substrate are bonded to each other. As the support substrate, for example, a sapphire substrate, an alumina substrate, a spinel substrate, or a silicon substrate can be used.
A metal pattern 7 and a plurality of bump pads 9 are formed on the wiring substrate 3. The metal pattern 7 is formed in an outer edge portion of the wiring substrate 3. The bump pad 9 is formed inside the metal pattern 7. As the metal pattern 7 and the bump pad 9, for example, copper or an alloy containing copper can be used. The metal pattern 7 and the bump pad 9 may for example have the thickness of 10 μm to 35 μm.
A sealing resin member 17 is formed to cover the device chip 5. The sealing resin member 17 may be made of, for example, an insulator such as a synthetic resin, or a metal. As the synthetic resin, for example, epoxy resin, polyimide, or the like can be used, but the present invention is not limited thereto. Preferably, an epoxy resin is used to form the sealing resin member 17 with a low temperature curing process.
The device chip 5 is mounted on the wiring substrate 3 via a bump 15 by flip-chip bonding.
As the bump 15, for example, a gold bump can be used. The height of the bump 15 is, for example, 20 μm to 50 μm.
The bump pad 9 is electrically connected to the device chip 5 via the bump 15.
As shown in
The metal pattern 7 may be intermittently formed, because it is not entirely necessary to be a single metal pattern.
A region AREA17 sandwiched between a solid line indicating the outer edge of the wiring substrate 3 and a solid line indicating the outer edge of the device chip 5 indicates a region to which the sealing resin member 17 is bonded to. The region AREA 17 to which the sealing resin member 17 is bonded includes a region to be bonded to the wiring substrate 3 and a region to be bonded to the metal pattern 7 formed on the wiring substrate 3. That is, the sealing resin member 17 (not shown in
The metal pattern 7 enhances the thermal conductivity between the wiring substrate 3 and the sealing resin member 17, and improves the heat dissipation property of the acoustic wave device. The boundary line becomes long because the boundary of the region where the sealing resin member 17 is bonded to the wiring substrate 3 and the region where the sealing resin member 17 is bonded to the metal pattern 7 is uneven or jagged shape. Further, the sealing resin member 17 enters in the concave portion of the metal pattern 7 of the uneven shape, or in the valley portion of the metal pattern 7 of the jagged shape. This exerts the anchor effect, and enhances the adhesion between the sealing resin member 17 and the wiring substrate 3.
As shown in
As shown in
As shown in
Here, there is a problem that the sealing resin infiltrates between the wiring substrate 3 and the device chip 5 and comes into contact with a functional element formed on the device chip 5 in the step of forming the sealing resin member 17. In the region CENTER formed so that the direction of the tip of the uneven or the jagged shaped portion is oriented toward the center of the wiring substrate 3, the press during the sealing resin member 17 makes the metal pattern 7 a wall and the sealing resin easily infiltrates between the wiring substrate 3 and the device chip 5 since the thickness of the metal pattern 7 is considerably 10 μm to 35 μm for example.
It is desirable to make the length OUTERLENGTH as long as possible in the region R1 because the functional element is often formed relatively close to the outer edge of the device chip 5 along the short side direction of the wiring substrate 3.
It is desirable that the resonator on the device chip 5 disposed in the vicinity of the region CENTER formed so that the direction of the tip of the uneven or the jagged shaped portion is oriented toward the center of the wiring substrate 3 is formed at a position as far as possible from the outer edge of the device chip 5. Further, it is desirable that the resonator on the device chip 5 disposed in the vicinity of the region OUTER formed so that the direction of the tip of the uneven or the jagged shaped portion is oriented toward the outer edge of the wiring substrate 3 is formed close to the outer edge of the device chip 5 from the viewpoint of space-efficiency because it is unlikely that the sealing resin infiltrates and comes into contact even though it is formed close to the outer edge of the device chip 5.
As shown in
In the region R3 and the region R4 are regions between bump pads in which a length of a region formed in the region R3 and/or region R4 in the tip direction of the uneven or the jagged portion of the metal pattern 7 that is oriented toward the outer edge of the wiring substrate 3 is longer than a length of a region formed in the region R3 and/or region R4 in the tip direction of an uneven portion or a jagged portion of the metal pattern 7 that is oriented toward the center of the wiring substrate 3.
The region R3 and the region R4 are contiguous, the two regions, between the bump pads respectively, having lengths in the tip direction of the uneven or the jagged portion of the metal pattern 7 that is oriented toward the outer edge of the wiring substrate 3 are longer than lengths in the tip direction of the uneven or the jagged portion of the metal pattern 7 that is oriented toward the center of the wiring substrate 3, the regions are consecutively formed. The bump pad formed in the center of the region R3 and the region R4 is a ground pad GND97. As described above, the ground pad GND97 is electrically connected to the metal pattern 7.
As shown in
An insulator 56 is formed on the wiring pattern 54. As the insulator 56, for example, polyimide can be used. The insulator 56 is formed of a film having the thickness of, for example, 1000 nm.
The wiring pattern 54 is also formed on the insulator 56, and wiring is formed so as to three-dimensionally cross each other via the insulator 56.
The acoustic wave element 52 and the wiring pattern 54 are made of an alloy or an appropriate metal such as silver, aluminum, copper, titanium, or palladium. The metal patterns may be formed of a laminated metal film formed by laminating a plurality of metal layers. The acoustic wave element 52 and the wiring pattern 54 may have the thickness of, for example, 150 nm to 400 nm.
The wiring pattern 54 includes wiring constituting the input pad In, the output pad Out, and the ground pad GND. The wiring pattern 54 is electrically connected to the acoustic wave element 52.
As shown in
The electric signal input from the input-pad In passes through the band-pass filter, and an electric signal of a desired frequency band is output to the output-pad Out.
The electric signal output to the output pad Out is output from an external connecting terminal 31 of the wiring substrate 3 via a bump 15 and the bump pad 9.
As shown in
The comb-shaped electrode 52c has a busbar 52e connecting a plurality of electrode fingers 52d and the plurality of electrode fingers 52d. The reflector 52b are provided on both sides of IDT52a.
IDT 52a and the reflector 52b are made of, for example, aluminium-copper alloys. IDT 52a and the reflector 52b have the thickness of, for example, 150 nm to 400 nm.
IDT 52a and reflector 52b may include an appropriate metal, such as titanium, palladium, silver, or the like, and may be formed of these alloys. IDT 52a and the reflector 52b may be formed of a laminated metal film formed by laminating a plurality of metal layers.
As shown in
As the chip substrate 60, for example, a semiconductor substrate such as silicon or an insulating substrate such as sapphire, alumina, spinel, or glass can be used. For example, aluminum nitride can be used for the piezoelectric film 62.
A metal such as ruthenium can be used for the lower electrode 64 and the upper electrode 66 for example.
The acoustic wave element 52 can be appropriately employed in a multimode filter or a ladder filter so as to obtain characteristics as a desired band-pass filter.
As shown in
Here, as seen from
According to the first embodiment of the present invention described above, it is possible to provide an acoustic wave device superior in heat dissipation capability and adhesion between a sealing resin member and a wiring substrate, and the acoustic wave device includes excellent characteristics in which coupling between a metal pattern through which an electric signal of a desired frequency band passes and a metal pattern through which an electric signal of a desired frequency band does not pass is unlikely to occur, while an amount of infiltration of a sealing resin between the wiring substrate and a device chip is controlled.
Next, the second embodiment of the present invention will be described.
As shown in
The wiring substrate 130 has a plurality of external connection terminals 131. The plurality of external connection terminals 131 are mounted on a motherboard of a specific mobile communication terminal.
On the main surface of the wiring substrate 130 a first inductance 111 and a second inductor 112 are mounted for impedance matching. The module 100 is sealed by a sealing resin member 117 for sealing a plurality of electronic components including the acoustic wave device 1.
An integrated-circuit component IC is mounted inside the circuit substrate 130. Although not shown, the integrated circuit component IC includes a switching circuit SW, a first low-noise amplifier LNA1, and a second low-noise amplifier LNA2.
As shown in
A signal passing through the first band-pass filter BPF1 and a signal passing through the second band-pass filter BPF2 are separated by the switching circuit SW from the common-input terminal 101.
The signal that has passed through the first band-pass filter BPF1 is impedance-matched by the first inductor 111, amplified by the first low-noise amplifier LNA1, and output from the first output terminal 103. Alternatively, when the first band-pass filter BPF1 is a transmitting filter, the first output terminal 103 functions as an input terminal, and the signal amplified by the first low-noise amplifier LNA1 and impedance-matched by the first inductor 111 passes through the first band-pass filter BPF1 and is transmitted from the antenna terminal.
The signal that has passed through the second band-pass filter BPF2 is impedance-matched by the second inductor 112, amplified by the second low-noise amplifier LNA2, and output from the second output terminal 105. Alternatively, when the second band-pass filter BPF2 is a transmitting filter, the second output terminal 105 functions as an input terminal, and the signal amplified by the second low-noise amplifier LNA2 and impedance-matched by the second inductor 112 passes through the second band-pass filter BPF2 and is transmitted from the antenna terminal.
Other configurations are omitted because they are the same as those of the explanation in the first embodiment.
According to the second embodiment of the present invention described above, it is possible to provide a module having an acoustic wave device superior in heat dissipation capability and adhesion between a sealing resin member and a wiring substrate, and the acoustic wave device includes excellent characteristics in which coupling between a metal pattern through which an electric signal of a desired frequency band passes and a metal pattern through which an electric signal of a desired frequency band does not pass is unlikely to occur, while an amount of infiltration of a sealing resin between the wiring substrate and a device chip is controlled. It should be noted that, of course, the present disclosure is not limited to the embodiments described above, but includes the embodiments that can achieve the purpose of the present disclosure
While several aspects of at least the embodiment have been described, it is to be understood that various modifications and improvements will readily occur to those skilled in the art.
Such modifications and improvements are intended to be part of the present disclosure and are intended to be within the scope of the present disclosure. It is to be understood that the embodiments of the methods and apparatus described herein are not limited in application to the structural and ordering details of the components set forth in the foregoing description or illustrated in the accompanying drawings. Methods and apparatus may be implemented in other embodiments or implemented in various manners. Specific implementations are given here for illustrative purposes only and are not intended to be limiting.
The phraseology and terminology used in the present disclosure are for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” “having,” and variations thereof herein means the inclusion of the items listed hereinafter and equivalents thereof, as well as additional items. The reference to “or” may be construed so that any term described using “or” may be indicative of one, more than one, and all of the terms of that description. References to front, back, left, right, top, bottom, and side are intended for convenience of description. Such references are not intended to limit the components of the present disclosure to any one positional or spatial orientation. Accordingly, the foregoing description and drawings are by way of example only.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-185860 | Nov 2022 | JP | national |
