CN116346070A

CN116346070A - Filtering module, circuit board assembly and electronic equipment

Info

Publication number: CN116346070A
Application number: CN202111597525.4A
Authority: CN
Inventors: 代翔宇; 叶润清; 姚明军
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2021-12-24
Filing date: 2021-12-24
Publication date: 2023-06-27

Abstract

The embodiment of the application provides a filter module, a circuit board assembly and electronic equipment. The filtering module comprises a piezoelectric substrate, and a transducer layer is arranged on one side of the piezoelectric substrate; the packaging layer is connected with the piezoelectric substrate and provided with a groove with an opening facing the piezoelectric substrate, and the transducer layer is arranged in the groove; the first matching layer is arranged on one side of the piezoelectric substrate, which is far away from the transducer layer; and the first electric connector is connected with the first matching layer and penetrates through the piezoelectric substrate and the packaging layer. By providing the first matching layer on the piezoelectric substrate, miniaturization and integration of the filter module and the like can be improved.

Description

Filtering module, circuit board assembly and electronic equipment

Technical Field

The embodiment of the application relates to the field of electronic equipment and the field of radio frequency. And more particularly to a filter module, a circuit board assembly, an electronic device.

Background

The filter module is widely applied to the wireless communication scene of the electronic equipment. The filtering module may include a filter. The filter module can also comprise a matching element corresponding to the filter, and the performance of the filter is improved under the action of the matching element. The matching element may be, for example, a capacitive/inductive element or the like. The matching element may be integrated onto a silicon substrate, which is electrically connected to the piezoelectric substrate of the filter by wafer bonding and packaged. However, to reduce warpage of the silicon substrate due to wafer bonding, the silicon substrate generally requires a larger thickness, which in turn increases the thickness of the overall filter module. Therefore, how to further miniaturize and highly integrate the filter module is one of the problems to be solved.

Disclosure of Invention

The embodiment of the application provides a filter module, a circuit board assembly and electronic equipment, and aims to improve miniaturization and integration of the filter module and the like.

In a first aspect, a filter module is provided, including:

a piezoelectric substrate, one side of which is provided with a transducer layer;

the packaging layer is connected with the piezoelectric substrate and provided with a groove with an opening facing the piezoelectric substrate, and the transducer layer is arranged in the groove;

the first matching layer is arranged on one side of the piezoelectric substrate, which is far away from the transducer layer;

and the first electric connector is connected with the first matching layer and penetrates through the piezoelectric substrate and the packaging layer.

The first matching layer is arranged on one side, far away from the transducer layer, of the piezoelectric substrate, so that the thickness of the filter module is reduced, the area of the circuit board is reduced, and the miniaturization and integration degree of the whole module are higher.

With reference to the first aspect, in certain implementations of the first aspect, the filter module further includes a second electrical connector, where the second electrical connector is connected to the transducer layer and penetrates the encapsulation layer.

The second electrical connector penetrates through the packaging layer, so that the first matching layer far away from the packaging layer can be electrically connected with a circuit close to the packaging layer. Through setting up the second electrical connector and running through the encapsulation layer, can make the encapsulation more stable, it is higher to integrate.

With reference to the first aspect, in certain implementations of the first aspect, the first electrical connector and the second electrical connector are both located outside the recess.

By arranging the first electric connector and the second electric connector outside the groove, the processing steps of the electric connectors are simplified.

With reference to the first aspect, in certain implementation manners of the first aspect, the first electrical connector and the second electrical connector pass through the groove, the encapsulation layer includes a support wall and a support layer that are stacked, the support wall is connected with the piezoelectric substrate and has a cavity, the support wall is a wafer bonding ring, and a material of the support layer is silicon.

The supporting wall is arranged to be a silicon substrate material, and the supporting wall is arranged to be a wafer bonding ring, so that packaging is more stable.

With reference to the first aspect, in certain implementation manners of the first aspect, the filter module further includes a second matching layer and a third electrical connector, where the second matching layer is disposed on a side of the encapsulation layer near the piezoelectric substrate and is located in the groove, the third electrical connector is connected to the second matching layer, and the third electrical connector penetrates through the support layer.

Through setting up the second matching layer at the encapsulation layer, be favorable to increasing the matching component that the filter module can hold, be favorable to taking into account miniaturization when promoting the filter module integration.

With reference to the first aspect, in certain implementations of the first aspect, the third electrical connector is part of the first electrical connector or the second electrical connector.

Through with third electric connector and first electric connector or second electric connector integrated into one piece, can save step and cost, the integrated level of whole module is also higher.

With reference to the first aspect, in certain implementations of the first aspect, the second electrical connector is part of the first electrical connector.

Through first electric connector and second electric connector integrated into one piece, can save process and cost, the degree of integrating simultaneously is higher.

With reference to the first aspect, in certain implementations of the first aspect, the first matching layer includes a capacitance and/or an inductance.

By using capacitors and/or inductors, a better co-operation of the filter is achieved. The type of device used for the first matching layer may be relatively flexible.

With reference to the first aspect, in certain implementations of the first aspect, the piezoelectric substrate includes a substrate base layer and a piezoelectric layer that are stacked, the substrate base layer is located on a side of the piezoelectric substrate away from the transducer layer, the piezoelectric layer is located on a side of the piezoelectric substrate away from the first matching layer, and the piezoelectric layer has a lower resistivity than the substrate base layer.

By providing a substrate base layer, the emission of acoustic waves of the transducer layer to a space remote from the encapsulation layer can be reduced.

With reference to the first aspect, in certain implementations of the first aspect, the material of the substrate base layer is high-resistance silicon.

By setting the substrate base layer as a high-resistance silicon substrate, the property of high sound velocity of the high-resistance silicon substrate can be well utilized to reduce the emission of sound waves of the transducer layer to a space far away from the packaging layer.

With reference to the first aspect, in certain implementation manners of the first aspect, the filter module is a thin film surface acoustic wave filter module.

The filter module is a film surface acoustic wave filter module, so that the performance of the filter module is better.

With reference to the first aspect, in certain implementations of the first aspect, the first matching layer is fabricated by integrated passive device technology.

The matching layer may be made integral with the substrate layer by processing the matching layer using integrated passive device technology.

In a second aspect, a circuit board assembly is provided, comprising a filter module as described in any one of the implementations of the first aspect.

With reference to the second aspect, in certain implementations of the second aspect, the circuit board assembly further includes: the third matching element is arranged on the circuit board and is positioned outside the filtering module.

Through setting up the matching element outside the filter module, can make the matching element's that cooperates the filter work the number more, simultaneously, the position of planning different grade type matching element that can be better is favorable to carrying out nimble matching to the filter module.

In a third aspect, an electronic device is provided, including a filter module as described in any one of the above first aspects.

In a fourth aspect, there is provided an electronic device comprising a circuit board assembly as described in any of the above second aspects.

Drawings

Fig. 1 is a schematic structural view of an electronic device.

Fig. 2 is a schematic block diagram of a radio frequency module.

Fig. 3 is a schematic structural diagram of a filter.

Fig. 4A is a schematic structural diagram of a filter module provided in an embodiment of the present application.

Fig. 4B is a schematic block diagram of a transducer layer provided in an embodiment of the present application.

Fig. 4C is a schematic structural diagram of a matching layer provided in an embodiment of the present application.

Fig. 5 is a schematic block diagram of another filter module according to an embodiment of the present application.

Fig. 6 is a schematic structural diagram of a circuit board assembly according to an embodiment of the present application.

Fig. 7 is a schematic structural diagram of yet another circuit board assembly provided in an embodiment of the present application.

Fig. 8 is a schematic flowchart of a processing method of a filter module according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

The electronic device 100 may be, for example, an end consumer product or a 3C electronic product (computer), a communication, a consumer (consumer) electronic product, such as a wristwatch, an earphone, a mobile phone, a mobile power supply, a portable device, a tablet computer, an electronic reader, a notebook computer, a digital camera, a car computer, a wearable device, etc. The embodiment shown in fig. 1 is illustrated with an electronic device 100 being a mobile phone. It should be understood that the structure of the electronic device 100 shown in fig. 1 is only some embodiments, and that different embodiments of the electronic device 100 are possible.

As shown in fig. 1, the electronic device 100 may be, for example, a cell phone. The electronic components within the electronic device 100 may include, for example, the radio frequency module 20. The rf module 20 may be a circuit board assembly or the rf module 20 may be part of a circuit board assembly. In the embodiment shown in fig. 1, the rf module 20 may be disposed on a motherboard inside a mobile phone, for example.

Fig. 2 is a schematic block diagram of a radio frequency module.

As shown in fig. 2, the rf module 20 includes an antenna, a switch 203, a filter 204, a filter 205, an amplifying circuit 206, an amplifying circuit 207, and a transceiver.

The antenna is used for sending the radio frequency signal processed by the baseband chip to the outside, or receiving the radio frequency signal from the outside, and the switch 203 is used for switching the antenna to receive or transmit the radio frequency signal.

The filter is used for filtering noise signals and other unwanted frequency signals in the radio frequency signal. For example, the filter 204 filters the rf signal processed through the baseband chip, and the filter 205 filters the external rf signal.

The amplifying circuit is used for amplifying the radio frequency signal. For example, the amplification circuit 206 is used to amplify radio frequency signals from a transceiver. The amplifying circuit 207 is for amplifying a radio frequency signal from the outside. In some embodiments, the amplification circuit 207 may include a low noise amplifier (low noise amplifier, LNA). In some embodiments, the amplifying circuit 206 includes a Power Amplifier (PA)

The transceiver is connected with the baseband chip and is used for receiving the radio frequency signals from the baseband chip or transmitting the radio frequency signals to the baseband chip. The antenna and filter 204, the amplifying circuit 206 and the transceiver constitute a transmitting circuit of the radio frequency front end, and the antenna and filter 205, the amplifying circuit 207 and the transceiver constitute a receiving circuit of the radio frequency front end.

The working principle of the receiving circuit is as follows: the antenna is connected to one port of the switch 203, the radio frequency signal received by the antenna is sent to the filter 205, the filter 205 is used for filtering the received radio frequency signal, the other end of the filter circuit 205 is connected to one port of the amplifying circuit 207, and the amplifying circuit 207 is used for amplifying the received radio frequency signal. The other end of the amplifying circuit 207 is connected to a transceiver for receiving the radio frequency signal and transmitting it to a baseband chip for further processing.

The working principle of the transmitting circuit is as follows: the transceiver receives the rf signal from the baseband chip, and the other port of the transceiver is connected to an amplifying circuit 206, and the rf signal can be amplified by the amplifying circuit 206, and the other end of the amplifying circuit 206 is connected to one end of a filter 205, so that the rf signal is sent to the filter 205 for filtering, and the other end of the filter 205 is connected to the other end of a switch 203, so that the rf signal is sent to an antenna, and thus the rf signal is emitted via the antenna.

In some embodiments, the rf module 20 further includes an antenna tuner (not shown) connected to the antenna and the switch 203 for matching the transmitted rf signal with the antenna.

The above-described individual components are electrically connected to each other by being electrically connected to a circuit board (not shown in the figure). The circuit board may be referred to as a substrate. In some embodiments, the above components are each processed with PINs, also referred to as PIN PINs, which may correspond to the ports described above, to make electrical connection with the circuit board.

In other embodiments, the components of rf module 20 may be arranged in a different manner than that of fig. 2, which is not limited in any way herein.

Fig. 3 shows a schematic structural diagram of a filter 300.

First, several concepts referred to hereinafter will be briefly described.

A. Matching element

The matching element is an inductive or capacitive element, which may be connected in parallel or in series with a filter for filtering the radio frequency signal.

B. Surface acoustic wave filter

Surface acoustic wave (surface acoustic wave, SAW) filters, simply SAW filters, are filtered primarily by the process of electro-surface acoustic wave-acoustic conversion. A surface acoustic wave is an elastic wave that propagates along the surface of an object. An elastic wave that is generated and propagated at the surface of a piezoelectric material and whose amplitude decreases rapidly with increasing depth into the substrate material. The basic structure of SAW filters is to make one or more resonators on a polished surface of a substrate material having piezoelectric properties, which may be composed of a plurality of interdigital transducers (interdigital transducer, IDTs) which typically cross each other.

In order to realize a specific filtering function, different numbers of resonators may be provided, and the plurality of resonators may be connected in series/parallel, which is not limited in the embodiment of the present application.

Taking a SAW filter as an example, the SAW filter has 2 resonators, wherein 1 of the 2 resonators is a transmitting resonator for converting a radio frequency signal into a surface acoustic wave, the surface acoustic wave propagates on the surface of a piezoelectric material, and after passing through a certain delay, the other 1 is a receiving resonator for converting the acoustic signal into an electrical signal for output. The filtering process is implemented in the electrical to acoustic and acoustic to electrical conversion so that the SAW filter can be equivalent to a two port passive network.

C. Interdigital transducer

The interdigital transducer can be a metal pattern formed on the surface of a piezoelectric material, which functions to effect acoustic-electrical transduction. The working principle of the surface acoustic wave device is as follows: when the transmitting resonator on the piezoelectric material is excited by the alternating electric signal, a periodically distributed electric field is generated, and corresponding elastic deformation is excited near the surface of the piezoelectric material due to the inverse piezoelectric effect, so that the vibration of solid particles is caused, and the surface acoustic wave propagating along the surface of the piezoelectric material is formed. When the surface acoustic wave is transmitted to the other end of the piezoelectric material, electric charges are generated at the two ends of the metal electrode due to the positive piezoelectric effect, so that an alternating electric signal can be output.

As shown in fig. 3, the filter 300 includes a piezoelectric substrate 310, a transducer layer 313, and an encapsulation layer 320. The encapsulation layer 320 has a recess opening towards the piezoelectric substrate 310, wherein the transducer layer 313 is arranged at one side of the piezoelectric substrate 310 and is located within the recess.

In some embodiments, piezoelectric substrate 310 includes a substrate base layer 311 and a piezoelectric layer 312 that are stacked, substrate base layer 311 being located on a side of piezoelectric substrate 310 remote from transducer layer 313, and piezoelectric layer 312 being located on a side of piezoelectric substrate 310 proximate to encapsulation layer 320. The transducer layer 313 may be disposed on a side of the piezoelectric substrate 310 proximate to the piezoelectric layer 312. In some embodiments, the substrate layer 311 is a high-resistance-resistivity silicon (HRS) material, which has the characteristics of high sound speed, good heat dissipation, and the like, and the resistivity is typically greater than 10000 Ω×cm. The substrate base layer 311 serves primarily to block the diffusion of energy from the piezoelectric layer 312 into the space away from the circuit board. In some embodiments, the material of the piezoelectric layer 312 may be silicon dioxide, siO ₂ Lithium tantalate LiTaO ₃ Lithium niobate LiNbO ₃ Etc. The resistivity of the piezoelectric layer 312 is lower than the substrate base layer 311.

One side of the piezoelectric substrate 310 is provided with a transducer layer 313. The transducer layer 313 comprises a first port 3131, a resonator 3132, a first electrical connection line 3133. One end of the first electrical connection line 3133 is in physical contact with the first port 3131 and the other end is in physical contact with a port of the resonator 3132. In some possible implementations, the first port 3131 may be part of the first electrical connection line 3133. In other possible implementations, the first port 3131 may be a device made of a metallic material.

The encapsulation layer 320 is connected to the piezoelectric substrate 310 and has a recess opening towards the piezoelectric substrate 310, in which recess the transducer layer 313 is arranged. In some embodiments, the encapsulation layer 320 includes a support wall 321 and a support layer 322 that are stacked, wherein the support wall 321 is connected to the piezoelectric substrate 310, and the support wall 321 has a cavity, a side surface of the cavity is a sidewall surface of the groove, a top surface of the cavity is a top surface of the groove, a bottom surface of the cavity is a bottom surface of the groove, and the cavity can accommodate the transducer layer 313 for protecting the resonator 3132. In some embodiments, the support wall 321 may be a Polyimide (PI) material. In some embodiments, the support layer 322 is also PI material. The support walls 321 and the support layers 322 are adhered to each other to realize sealing protection of the resonator 3132.

In some embodiments, the filter 300 may further include a second electrical connector 330, one end of the second electrical connector 330 is connected to the first port 3133, and the second electrical connector 330 penetrates the encapsulation layer 320, and the other end may be in physical contact with a second pin (not shown) disposed on a side of the encapsulation layer 320 away from the piezoelectric substrate 310, which may be disposed on a signal layer or a ground layer of the circuit board, thereby implementing access to the circuit by the transducer layer 313. In some possible embodiments, the second electrical connector 330 passes through a recess of the encapsulation layer 320, and the first electrical connector 450 includes a portion that passes through the recess of the encapsulation layer 320 and a portion that passes through the encapsulation layer 320 that is not a recess. In other possible implementations, the second electrical connector 330 is located outside the recess of the encapsulation layer 320, and the second electrical connector 330 includes only a portion that passes through the non-recess of the encapsulation layer 320, so that the processing of the electrical connector is simpler and easier to implement. In some embodiments, the portion of the second electrical connector 330 that passes through the encapsulation layer 320 that is not a recess may be a conductive via. In some embodiments, the portion of the second electrical connector 330 that passes through the recess of the encapsulation layer 320 may be a copper wire or a copper pillar.

In some embodiments, the filter 300 may be a thin film surface acoustic wave filter.

The piezoelectric layer 312 and the transducer layer 313 are used for filtering. Since the resonator includes a plurality of pairs of crossing electrodes forming a comb-like structure, the spacing between the combs determines the SAW wavelength, and a plurality of resonators may also be connected in series/parallel to achieve different filtering requirements. In this way, the filter 300 may filter the radio frequency signal.

The received signal filtering principle is as follows: the resonator 3132 connected to the input signal terminal receives the excitation of the alternating electric signal, and generates a periodically distributed electric field, and due to the inverse piezoelectric effect, corresponding elastic deformation is excited near the surface of the piezoelectric substrate 310 near the transducer layer 313, so as to cause vibration of solid particles, and the formed surface acoustic wave is transmitted along the surface of the piezoelectric substrate 310 near the transducer layer 313.

The filtering principle of the transmitting signal is as follows: the resonator 3132 connected to the output signal terminal receives the surface acoustic wave because the positive piezoelectric effect generates electric charges across the metal electrode, thereby outputting an alternating electric signal.

The filter module can also comprise a matching element corresponding to the filter, and the performance of the filter is improved under the action of the matching element. The matching element may be, for example, a capacitive/inductive element or the like. The matching element may be integrated onto a silicon substrate, which is electrically connected to the piezoelectric substrate of the filter by wafer bonding and packaged. However, to reduce warpage of the silicon substrate due to wafer bonding, the silicon substrate generally requires a larger thickness, which in turn increases the thickness of the overall filter module.

In combination with the embodiment shown in fig. 3, the technical scheme provided by the application aims to promote miniaturization and integration of the filter module through reasonable structural design of the filter module.

Fig. 4A-4C, 5, 6 and 7 illustrate schematic structural diagrams of a filter module 400 according to an embodiment of the present application. The filter module 400 may be used in either a radio frequency receiving circuit or a radio frequency transmitting circuit.

A filter module 400 according to an embodiment of the present application is described with reference to fig. 4A-4C.

As shown in fig. 4A, the filter module 400 includes a piezoelectric substrate 310, a package layer 320, a transducer layer 313, a first matching layer 440, and a first electrical connection 450. The piezoelectric substrate 310 is connected to an encapsulation layer 320, the encapsulation layer 320 having a recess opening towards the piezoelectric substrate 310, the transducer layer 313 being located on one side of the piezoelectric substrate 310 and within the recess. The first matching layer 440 is located on the side of the piezoelectric substrate 310 remote from the transducer layer 313. One end of the first electrical connector 450 is connected to the first matching layer 440 and penetrates the piezoelectric substrate 310 and the encapsulation layer 320.

In some embodiments, piezoelectric substrate 310 includes a substrate base layer 311 and a piezoelectric layer 312 that are stacked, substrate base layer 311 being located on a side of piezoelectric substrate 310 remote from transducer layer 313, and piezoelectric layer 312 being located on a side of piezoelectric substrate 310 remote from first matching layer 440. In some embodiments, the substrate layer 311 is a high-resistance silicon material, which has the characteristics of high sound speed, good heat dissipation, and the like, and the resistivity is typically greater than 10000 Ω×cm. The substrate base layer 311 serves primarily to block the diffusion of energy from the piezoelectric layer 312 into the space away from the circuit board. In some embodiments, the piezoelectric layer 312 may be silicon dioxide, siO ₂ Lithium tantalate LiTaO ₃ Lithium niobate LiNbO ₃ Etc. The resistivity of the piezoelectric layer 312 is lower than the substrate base layer 311.

As shown in fig. 4B, the transducer layer 313 includes a first port 3131, a resonator 3132, and a first electrical connection line 3133. One end of the first electrical connection line 3133 is in physical contact with the first port 3131 and the other end is in physical contact with a port of the resonator 3132. In some possible implementations, the first port 3131 may be part of the first electrical connection line 3133. In other possible implementations, the first port 3131 may be a metallic material device.

The encapsulation layer 320 is connected to the piezoelectric substrate 310 and has a recess opening towards the piezoelectric substrate 310, in which recess the transducer layer 313 is arranged. In some embodiments, the encapsulation layer 320 includes a support wall 321 and a support layer 322 that are stacked, wherein the support wall 321 is connected to the piezoelectric substrate 310, and the support wall 321 has a cavity, a side surface of the cavity is a sidewall surface of the groove, a top surface of the cavity is a top surface of the groove, a bottom surface of the cavity is a bottom surface of the groove, and the cavity can accommodate the transducer layer 313 for protecting the resonator 3132. In some embodiments, the support wall 321 may be PI material. In some embodiments, the support layer 322 may also be a PI material. The supporting wall 321 and the supporting layer 322 are adhered to each other to realize sealing protection of the resonator 3132.

In some embodiments, the filter 300 may further include a second electrical connector 330, one end of the second electrical connector 330 is connected to the first port 3133, and the second electrical connector 330 penetrates the encapsulation layer 320, and the other end may be in physical contact with a second pin 402 disposed on a side of the encapsulation layer 320 remote from the piezoelectric substrate 310, and the second pin 402 may be disposed on a signal layer or a ground layer of a circuit board, thereby implementing access to a circuit by the transducer layer 313. In some possible embodiments, the second electrical connector 330 passes through a recess of the encapsulation layer 320, and the first electrical connector 450 includes a portion that passes through the recess of the encapsulation layer 320 and a portion that passes through the encapsulation layer 320 that is not a recess. In other possible implementations, the second electrical connector 330 is located outside the recess of the encapsulation layer 320, and the second electrical connector 330 includes only a portion that is not recessed through the encapsulation layer 320. In some embodiments, the portion of the second electrical connector 330 that passes through the encapsulation layer 320 that is not a recess may be a conductive via. In some embodiments, the portion of the second electrical connector 330 that passes through the recess of the encapsulation layer 320 may be a copper wire or a copper pillar.

The first matching layer 440 is disposed on a side of the piezoelectric substrate 310 remote from the transducer layer 313. In some possible implementations, the first matching layer 440 may be processed through an integrated passive device (integrated passive device, IPD) process on the side of the piezoelectric substrate 310 remote from the transducer layer 313, in other words, the first matching layer 440 and the piezoelectric substrate 310 may be considered as a whole. As shown in fig. 4C, the first matching layer 440 includes a plurality of second ports 4401, one or more first matching elements 4402, and second electrical connection lines 4403. One end of the second electrical connection line 4403 is in physical contact with the second port 4401 and the other end is in physical contact with the port of the first mating element 4402. The one or more first matching elements 4402 are primarily used to filter the radio frequency signal, improving the performance of the filter 300. In one possible implementation, portions of the first matching elements 4402 are electrically connected to each other by second electrical connection lines 4403. In some embodiments, the first matching element 4402 may be a semiconductor capacitor, such as a metal oxide semiconductor (metal oxide semiconductor, MOS) capacitor, a metal-insulator-metal (metal insulator metal, MIM) capacitor, or a metal oxide metal (metal oxide metal, MOM) capacitor, wherein the MIM capacitor and MOM capacitor may be fabricated on a silicon substrate by IPD techniques. In some embodiments, the first matching element 4402 may be a semiconductor inductor. In some embodiments, the second electrical connection line 4403 may be a wire. In some embodiments, the second port 4401 may be part of the second electrical connection line 4403.

One end of the first electrical connector 450 is connected to the first matching layer 440, and the first electrical connector 450 penetrates through the piezoelectric substrate 310 and the encapsulation layer 320. In some embodiments, the first electrical connector 450 is coupled to the second port 4401. In some possible embodiments, the first electrical connector 450 extends through a recess of the encapsulation layer 320, the first electrical connector 450 including a portion that extends through the piezoelectric substrate 310, a portion that extends through the recess of the encapsulation layer 320, and a portion that extends through the encapsulation layer 320 that is not the recess. In other possible implementations, the first electrical connector 450 is located outside the recess of the encapsulation layer 320, and the first electrical connector 450 includes a portion that passes through the piezoelectric substrate 310 and a portion that passes through the encapsulation layer 320 without the recess, so that the electrical connector is simpler and easier to manufacture. In some embodiments, the other end of the first electrical connector 450 is connected to a first pin 401 disposed on a side of the encapsulation layer 320 remote from the piezoelectric substrate 310, the first pin 401 may be disposed on a signal layer or a ground layer of a circuit board, and thus, the first matching layer 440 may be implemented in an access circuit. In some embodiments, the portion of the first electrical connector 450 that passes through the piezoelectric substrate 310 may be a via that may be fabricated by way of through silicon via technology (through silicon via, TSV), with an electrically conductive material coated or filled therein. In some embodiments, the portion of the first electrical connector 450 that passes through the recess may be a copper post, a copper wire, or the like. In some embodiments, the portion of the first electrical connector 450 that passes through the non-recess of the encapsulation layer 320 may be a conductive via, which may be processed in a similar manner to the TSV process.

In other embodiments, the first electrical connector 450 is located outside the filter 300, and the first electrical connector 450 may be, for example, a wire, and one end of the wire is in physical contact with the second port 4401, and the other end is connected to the first pin 401 disposed on the side of the encapsulation layer 320 away from the piezoelectric substrate 310.

In some embodiments, the first electrical connector 450 is independent of the second electrical connector 330, it being understood that at this point the first matching layer 440 and the transducer layer 313 each make electrical connection with the circuit board 460 such that the first matching layer 440 and the transducer layer 313 make electrical connection through the circuit board 460.

In other embodiments, the first electrical connector 450 is connected to the second electrical connector 330, i.e., the second electrical connector 330 may be part of the first electrical connector 450, but care should be taken to locate the first electrical connector 450 at a position corresponding to the position of the first port 3131. The first electrical connector 450 may be integrally formed with the second electrical connector 330, so as to save processing steps and costs, and it should be understood that the first pin 401 and the second pin 402 are the same component. Since the first matching layer 440 and the transducer layer 313 are both connected to the second electrical connector 330, the first matching layer 440 is connected in series or parallel with the transducer layer 313, and the integration degree of the whole module is higher.

By disposing the first matching layer 440 on the side of the piezoelectric substrate 310 away from the transducer layer 313, the thickness of the filter module is advantageously reduced, and the area of the circuit board is also advantageously reduced, so that the overall module is miniaturized and integrated to a higher degree.

Fig. 5 shows a schematic structural diagram of a further filter module 400.

In some embodiments, the encapsulation layer 320 includes a support wall 321 and a support layer 322 that are stacked, wherein the support wall 321 is connected to the piezoelectric substrate 310, and the support wall 321 has a cavity, a side surface of the cavity is a sidewall surface of the groove, a top surface of the cavity is a top surface of the groove, a bottom surface of the cavity is a bottom surface of the groove, and the cavity can accommodate the transducer layer 313 for protecting the resonator 3132. The support layer 322 may be a portion of a silicon wafer, and the support wall 321 is a wafer bonding ring, and the material of the wafer bonding ring may be a metal material.

The first electrical connector 450 and the second electrical connector 330 each extend through the recess, i.e., the first electrical connector 450 and the second electrical connector 330 extend through the recess and the support layer 322.

As shown in fig. 5, the filter module 400 further includes a second matching layer 560 and a third electrical connector 570.

In addition to providing the first matching layer 440 on the side of the piezoelectric substrate 310 remote from the transducer layer 313, a second matching layer 560 may be provided on the side of the support layer 322 proximate to the piezoelectric substrate 310, with the second matching layer 560 being located within the recess.

The second matching layer 560 may include a third port 5601, a second matching element 5602, and a third electrical connection line 5603. In some embodiments, the second matching element 5602 may be a semiconductor capacitor, such as a metal oxide semiconductor (metal oxide semiconductor, MOS) capacitor, a metal-insulator-metal (metal insulator metal, MIM) capacitor, or a metal oxide metal (metal oxide metal, MOM) capacitor, wherein the MIM capacitor and MOM capacitor may be fabricated on a silicon substrate by IPD techniques. In some embodiments, the second matching element 5602 may be a semiconductor inductance. In some embodiments, the port of the second matching element 5602 is coupled to the third port 5601. In some embodiments, the port of the second matching element 5602 is connected to a third electrical connection 5603.

One end of the third electrical connector 570 is connected to the second matching layer 560 and penetrates the encapsulation layer 320. In some possible implementations, one end of the third electrical connector 570 is connected to the third port 5601. In some embodiments, the other end of the third electrical connector 570 may be connected to a third pin 501 disposed on a side of the encapsulation layer 320 remote from the piezoelectric substrate 310. In some embodiments, the third electrical connection 570 may be a via, which may be processed through a TSV process.

In some embodiments, the third electrical connector 570 is part of the second electrical connector 330, in other words, the third electrical connector 570 is integrally formed with the second electrical connector 330, it being understood that the third pin 501 is now the same component as the second pin 402. In some embodiments, the third electrical connector 570 is part of the first electrical connector 450, in other words, the third electrical connector 570 is integrally formed with the first electrical connector 450, and it should be understood that the third pin 501 is the same component as the first pin 401. In some embodiments, the third electrical connector 570 and the second electrical connector 330 are all part of the first electrical connector 450, in other words, the third electrical connector 570, the second electrical connector 330 and the first electrical connector 450 are integrally formed, and it should be understood that the first pin 401 is the same component as the second pin 402 and the third pin 501. Thus, the processing steps of the whole module can be simplified, and the integration degree is higher.

The circuit board assembly provided in the embodiments of the present application is described with reference to fig. 4, 5, 6 and 7.

The circuit board assembly 40 of fig. 4 and 5 may include a circuit board 460 in addition to the filter module 400. That is, the circuit board assembly 40 may include the aforementioned piezoelectric substrate 310, encapsulation layer 320, transducer layer 313, matching layer 440, first electrical connector 450, and circuit board 460. The filter module 400 including the above components can be connected to the circuit board 460 by providing the first pin 401 on the side of the encapsulation layer 320 away from the piezoelectric substrate 310 to be connected to the signal layer or the ground layer of the circuit board 460.

As shown in fig. 5, the circuit board assembly 40 may further include a second mating layer 560 and a third electrical connector 570.

Fig. 6 shows a schematic structural diagram of a further circuit board assembly 40.

The matching element of the filter 300 may include the third matching element 60 provided in addition to the first matching element 4402 provided in the first matching layer 440. As shown in fig. 6, the third matching element 60 is disposed on the circuit board 460 near the filter module 400 and on the same side of the circuit board 460 as the filter module 400. The surface of the third matching element 60 may be provided with pins to be plugged into the circuit board 460. In some embodiments, the third matching element 60 may comprise a discrete capacitive element. In some embodiments, the third mating element 60 may include a discrete inductive element.

In some embodiments, the third matching element 60 may be connected to the filter module 400 through an electrical connection 470 embedded in the circuit board 460.

Fig. 7 shows a schematic structural view of yet another circuit board assembly 40.

The matching elements of the filter module may include the first matching element 4402, the second matching element 5602, and the third matching element 60 of the previous embodiments. And the first matching element 4502 is disposed on the first matching layer 440, the second matching element 5602 is disposed on the second matching layer 560, and the third matching element 60 is disposed outside the filter 300.

The description of the first matching element 4402, the second matching element 5602, and the third matching element 60 is the same as that of the previous embodiment, and will not be repeated here.

The method of manufacturing the filter module 400 described above is described below with reference to fig. 8.

Fig. 8 is a schematic flow chart of a processing method of the filter module 400. The order of execution of the steps is not limited in this application.

801, a piezoelectric substrate 810 is obtained.

The wafer containing the piezoelectric substrate 810 may be obtained directly by purchase and then diced, or diced after other components and packaging are fabricated. Typically, the wafer comprises a substrate base 811 and a piezoelectric layer 312, which are stacked, the substrate base 811 is typically made of high-resistance silicon, and the piezoelectric layer is typically made of silicon oxide SiO ₂ Lithium tantalate LiTaO ₃ Lithium niobate LiNbO ₃ Etc.

802, thinning the piezoelectric substrate 810.

802 may be an optional step. In some embodiments, the thickness of the substrate base layer 811 is tailored to block the release of energy from the piezoelectric layer 312 into a space away from the piezoelectric layer 312. In addition, the reasonable design of the thickness of the substrate base 811 is also beneficial to further processing the TSV through-hole. Piezoelectric substrate 310 may be obtained after thinning piezoelectric substrate 810.

This step process may be, for example, grinding, lapping, dry polishing, and the like.

803, a transducer layer 313 is fabricated on the surface of the piezoelectric substrate 310.

Devices such as resonators may be formed on the surface of the piezoelectric substrate 310 by a photolithography process using a metal whose main component is aluminum or copper material.

At 804, a first portion 451 of the first electrical connection is fabricated through the piezoelectric substrate 310.

Typically, after the circuit is designed, the locations of the vias are determined according to the locations where the pins are to be processed, and the vias are processed on the piezoelectric substrate 310 using a TSV process. In some embodiments, the TSV through hole is sequentially formed from inside to outside by a conductive layer, a barrier layer and an insulating layer, where the conductive layer may be an electroplated copper layer for electrically connecting devices at two ends of the through hole, the barrier layer may be Ti, ta or TaN for preventing copper atoms from diffusing during annealing to penetrate the insulating layer, and the insulating layer may be silicon dioxide for isolating and insulating the conductive layer from the wafer. The steps may be: firstly, manufacturing a through hole by laser etching or deep reactive ion etching; the through holes are then filled by electroplating, chemical vapor deposition, polymer coating, or the like, and the filled material may be the material used for the three layers.

In other embodiments, the order of S730 may be reversed with S720.

805, processing the first matching layer 440.

This step may be performed, for example, by integrated passive device technology.

806, machining the supporting wall 321 and the supporting layer 322.

In some embodiments, the support wall 321 is formed around the resonator using PI material on the side of the piezoelectric substrate 310 where the transducer layer 313 is provided, and then the support layer 322 is formed on the side of the support wall 321 away from the piezoelectric substrate 310.

The process of fabricating the support wall 321 and the support layer 322 may be, for example, high temperature curing, compression molding, etc. of PI material.

807, the second electrical connector 330 and the second portion 452 of the first electrical connector are processed on the encapsulation layer.

The vias may be fabricated first and then conductive material deposited/coated over the vias, a process similar to the TSV process.

The foregoing is merely specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily think about changes or substitutions within the technical scope of the present application, and the changes and substitutions are intended to be covered by the scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A filter module (400), comprising:

a piezoelectric substrate (310), one side of the piezoelectric substrate (310) being provided with a transducer layer (313);

an encapsulation layer (320), the encapsulation layer (320) being connected to the piezoelectric substrate (310), the encapsulation layer (320) having a recess opening towards the piezoelectric substrate (310), the transducer layer (313) being arranged in the recess;

a first matching layer (440) disposed on a side of the piezoelectric substrate (310) remote from the transducer layer (313);

-a first electrical connection (450), said first electrical connection (450) being connected to said first matching layer (440) and penetrating said piezoelectric substrate (310) and said encapsulation layer (320).

2. The filter module (400) of claim 1, wherein the filter module (400) further comprises a second electrical connection (330), the second electrical connection (330) being connected to the transducer layer (313) and extending through the encapsulation layer (320).

3. The filter module (400) of claim 2, wherein the first electrical connector (450) and the second electrical connector (330) are both located outside the recess.

4. The filter module (400) according to claim 2, wherein the first electrical connector (450) and the second electrical connector (330) pass through the groove, the encapsulation layer (320) includes a support wall (321) and a support layer (322) that are stacked, the support wall (321) is connected to the piezoelectric substrate (310) and has a cavity, the support wall (321) is a wafer bonding ring, and the material of the support layer (322) is silicon.

5. The filter module (400) of claim 4, wherein the filter module (400) further comprises a second matching layer (560) and a third electrical connector (570), the second matching layer (560) is disposed on a side of the encapsulation layer (320) near the piezoelectric substrate (310) and in the recess, the third electrical connector (570) is connected to the second matching layer (560), and the third electrical connector (570) extends through the support layer (322).

6. The filter module (400) of claim 5, wherein the third electrical connection (570) is part of the first electrical connection (450) or the second electrical connection (330).

7. The filter module (400) of any of claims 2-6, wherein the second electrical connection (330) is part of the first electrical connection (450).

8. The filter module (400) according to any of claims 1 to 7, wherein the first matching layer (440) comprises a capacitance and/or an inductance.

9. The filter module (400) according to any of claims 1 to 8, wherein the piezoelectric substrate (310) comprises a substrate base layer (311) and a piezoelectric layer (312) arranged in a stack, the substrate base layer (311) being located on a side of the piezoelectric substrate (310) remote from the transducer layer (313), the piezoelectric layer (312) being located on a side of the piezoelectric substrate (310) remote from the first matching layer (440), the piezoelectric layer (312) having a lower electrical resistivity than the substrate base layer (311).

10. The filter module (400) of claim 9, wherein the material of the substrate base layer (311) is high-resistance silicon.

11. The filter module (400) according to any of claims 1 to 10, wherein the filter module (400) is a thin film surface acoustic wave filter module.

12. The filter module (400) of any of claims 1 to 11, wherein the first matching layer (440) is fabricated by integrated passive device technology.

13. A circuit board assembly (40) comprising a filter module (400) according to any of claims 1 to 12 and a circuit board (460).

14. The circuit board assembly (40) of claim 13, wherein the circuit board assembly (40) further comprises a third matching element (60), the third matching element (60) being disposed on the circuit board (460) and outside the filter module (400).

15. An electronic device (100) comprising a filter module (400) as claimed in any one of claims 1 to 12.

16. An electronic device (100) comprising a circuit board assembly (40) according to claim 13 or 14.