CN118539897A - Bulk acoustic wave filter and electronic equipment - Google Patents

Abstract

The present invention discloses a bulk acoustic wave filter and an electronic device, wherein the bulk acoustic wave filter comprises a metal cover, a substrate and a packaging substrate, wherein the metal cover comprises a sidewall metal layer and a bottom metal layer, wherein the sidewall metal layer and the bottom metal layer constitute a containing space; the substrate is located in the containing space, and the surface of the substrate on the side away from the bottom metal layer comprises a resonator setting area; the resonator setting area is provided with an input pad, an output pad and a plurality of bulk acoustic wave resonators electrically connected between the input pad and the output pad; the packaging substrate is located on the side of the substrate away from the bottom metal layer, the packaging substrate comprises a ground terminal, and the metal cover is electrically connected to the ground terminal. The technical solution provided by the present invention can improve the out-of-band suppression on the left and right sides of the passband, and improve the working reliability of the bulk acoustic wave filter.

Description

Bulk acoustic wave filter and electronic device

Technical Field

The present invention relates to the technical field of filters, and in particular to a bulk acoustic wave filter and electronic equipment.

Background Art

With the rapid development of mobile communication technology, a large number of RF filters will be needed on terminal devices, mainly used to filter out unnecessary RF signals, improve communication quality, and enhance user experience.

BAW filters use the piezoelectric effect of piezoelectric crystals to produce resonance. Since its resonance is generated by mechanical waves (bulk acoustic waves) rather than electromagnetic waves as the source of resonance, the wavelength of mechanical waves is much shorter than that of electromagnetic waves. Therefore, the volume of BAW resonators and filters composed of them is greatly reduced relative to the size of traditional electromagnetic filters. On the other hand, since the crystal growth of piezoelectric crystals can be well controlled at present, the loss of the resonator is extremely small, the quality factor is high, and it can cope with complex design requirements such as steep transition bands and low insertion loss. Due to the small size, high roll-off, and low insertion loss of BAW filters, filters with this as the core have been widely used in communication systems.

At present, communication systems are developing in the direction of multi-band, multi-system and multi-mode, and the used frequency bands are becoming more and more dense. In order to improve the communication quality and reduce the interference between the frequency bands, the out-of-band suppression degree of the filter is required to be higher. Usually, the out-of-band suppression is improved by increasing the number of filter stages. However, the disadvantage is that it will worsen the in-band insertion loss and increase the size of the filter, which is not conducive to the miniaturization of the device. Therefore, how to improve the out-of-band suppression of the bulk acoustic wave filter without worsening the filter insertion loss and increasing the filter size is still a problem that needs to be solved urgently.

Summary of the invention

The present invention provides a bulk acoustic wave filter and an electronic device to improve the out-of-band suppression on the left and right sides of a passband and to enhance the working reliability of the bulk acoustic wave filter.

In a first aspect, the present invention provides a bulk acoustic wave filter, comprising:

A metal cover, comprising a side wall metal layer and a bottom metal layer, wherein the side wall metal layer and the bottom metal layer form a receiving space;

A substrate, the substrate is located in the accommodation space, and a surface of the substrate on one side facing away from the bottom metal layer includes a resonator setting area; the resonator setting area is provided with an input pad, an output pad, and a plurality of bulk acoustic wave resonators electrically connected between the input pad and the output pad;

The packaging substrate is located on a side of the substrate away from the bottom metal layer. The packaging substrate includes a ground terminal, and the metal cover is electrically connected to the ground terminal.

Optionally, the BAW filter further comprises a peripheral region located on a surface of the substrate facing away from the bottom metal layer;

The peripheral area surrounds the resonator setting area, and a metal structure is provided in the peripheral area. The metal structure includes a connecting portion and an opening portion. The connecting portion is disconnected at the opening portion, and the connecting portion is electrically connected to the ground terminal.

Optionally, the metal cover is electrically connected to the ground terminal through the connecting portion.

Optionally, the BAW filter further comprises a conductive structure;

The conductive structure is electrically connected between the metal cover and the connecting portion.

Optionally, the BAW filter further comprises a bonding layer;

The metal cover is attached to the substrate through the adhesive layer.

Optionally, the conductive structure penetrates the bonding layer, and two ends of the conductive structure are in contact with the sidewall metal layer and the connecting portion respectively.

Optionally, the conductive structure penetrates the substrate and the bonding layer, and two ends of the conductive structure are electrically connected to the bottom metal layer and the connecting portion respectively.

Optionally, the thickness of the sidewall metal layer and/or the bottom metal layer of the metal cover is d;

Where, d≥2μm.

Optionally, the BAW filter further comprises at least two conductors;

The conductor is located in the resonator setting area, and the conductor is electrically connected to the connecting portion and the ground end respectively.

In a second aspect, the present invention provides an electronic device comprising the bulk acoustic wave filter described in the first aspect.

The technical solution provided by the present invention is that an input pad, an output pad and a plurality of BAW resonators electrically connected between the input pad and the output pad are arranged in a resonator arrangement area in a BAW filter, so that a radio frequency signal input to the input pad can be resonated and filtered by the BAW resonator and then output to the output pad. In addition, a packaging substrate and a metal cover electrically connected to the ground end of the packaging substrate are arranged, and the substrate is located in a containing space formed by a side wall metal layer and a bottom metal layer. During the operation of the BAW filter, the side wall metal layer or the bottom metal layer forms an inductive coupling with the resonator arrangement area, so as to reduce the electromagnetic coupling effect between the input pad and the output pad, improve the out-of-band suppression on the left and right sides of the passband, and improve the working reliability of the BAW filter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic cross-sectional view of a bulk acoustic wave filter provided by an embodiment of the present invention;

FIG2 is a schematic diagram of a top view of a substrate provided in an embodiment of the present invention;

3 is a schematic cross-sectional view of another bulk acoustic wave filter provided by an embodiment of the present invention;

FIG4 is a schematic cross-sectional view of another BAW filter provided by an embodiment of the present invention;

FIG5 is a schematic top view of another substrate provided by an embodiment of the present invention;

FIG6 is a passband performance curve diagram of a comparative example and an embodiment provided by the present invention;

FIG7 is a schematic structural diagram of a bulk acoustic wave resonator in the prior art;

FIG8 is a schematic cross-sectional structure diagram of a bulk acoustic wave resonator in the prior art;

FIG9 is a schematic cross-sectional view of another BAW resonator of the prior art;

10 is a schematic cross-sectional view of another bulk acoustic wave filter provided in an embodiment of the present invention;

FIG11 is a schematic cross-sectional view of another bulk acoustic wave filter provided by the present invention;

FIG12 is a passband performance curve diagram of another comparative example and an embodiment provided by the present invention;

13 is a schematic cross-sectional view of another bulk acoustic wave filter provided in an embodiment of the present invention;

14 is a schematic cross-sectional view of another BAW filter provided by an embodiment of the present invention;

15 is a schematic cross-sectional view of another bulk acoustic wave filter provided in an embodiment of the present invention;

FIG16 is a schematic cross-sectional view of a bulk acoustic wave filter provided by the present invention;

FIG17 is a passband performance curve diagram of another comparative example and an embodiment provided by the present invention;

FIG18 is a passband performance curve diagram of a comparative example and an embodiment provided by the present invention;

FIG. 19 is a schematic diagram of a top view of another substrate provided by an embodiment of the present invention.

DETAILED DESCRIPTION

The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

FIG1 is a schematic diagram of the cross-sectional structure of a bulk acoustic wave filter provided by an embodiment of the present invention, and FIG2 is a schematic diagram of the top view structure of a substrate provided by an embodiment of the present invention. Referring to FIG1 and FIG2 , the bulk acoustic wave filter 100 includes a metal cover 10, a substrate 20 and a packaging substrate 30, the metal cover 10 includes a sidewall metal layer 11 and a bottom metal layer 12, and the sidewall metal layer 11 and the bottom metal layer 12 constitute a receiving space; the substrate 20 is located in the receiving space, and the surface of the substrate 20 on one side away from the bottom metal layer 12 includes a resonator setting area 21; the resonator setting area 21 is provided with an input pad 23, an output pad 24 and a plurality of bulk acoustic wave resonators 25 electrically connected between the input pad 23 and the output pad 24; the packaging substrate 30 is located on the side of the substrate 20 away from the bottom metal layer 12, the packaging substrate 30 includes a ground terminal GND, and the metal cover 10 is electrically connected to the ground terminal GND.

Among them, the metal cover 10 includes metal materials such as copper, titanium or iron, the substrate 20 includes materials such as a silicon substrate, a silicon carbide substrate or a sapphire substrate, and the packaging substrate 30 includes at least two metal layers 31 and a dielectric layer 32 located between adjacent metal layers 31, so as to transmit electrical signals to the solder pads of the resonator setting area 21 through the metal layers 31 in the packaging substrate 30, so as to enable the bulk acoustic wave resonator 25 in the resonator setting area 21 to work. The number of metal layers in the packaging substrate 30 can be set according to actual needs and is not specifically limited here.

Specifically, the resonator setting area 21 is used to set the input pad 23, the output pad 24 and the BAW resonator 25 for resonant filtering of the BAW filter 100. The specific electrical connection method of each BAW resonator 25 can be set according to actual needs. For example, the resonator setting area 21 includes a plurality of BAW resonators 25 connected in series and a plurality of BAW resonators 25 connected in parallel. The input pad 23 is electrically connected to the output pad 24 through the plurality of BAW resonators 25. Since the setting area of the resonator setting area 21 is small, the distance between each BAW resonator 25 is small. When the RF signal is input from the input pad 23, the BAW resonator 25 is electrically connected to the output pad 24. Electromagnetic coupling will occur between the resonators 25, and then parasitic capacitance will be generated, resulting in different degrees of deterioration of the out-of-band suppression of the BAW filter 100 passband. By setting a metal cover 10 electrically connected to the ground terminal GND, the side wall metal layer 11 surrounds the resonator setting area 21, and the bottom metal layer 12 is located on the side of the substrate 20 away from the resonator setting area 21. The metal cover 10 can introduce parasitic inductance, which can be coupled with the parasitic capacitance in the resonator setting area 21 to suppress the electromagnetic coupling effect between the input pad 23 and the output pad 24, improve the out-of-band suppression of the passband, and improve the working reliability of the BAW filter 100.

It can be understood that the metal cover 10 itself can effectively isolate the interference of the external environment on the internal electronic components, prevent dust, water vapor, electromagnetic waves, etc. from entering the resonator setting area 21, and improve the working reliability of the resonator setting area 21, as well as the packaging reliability of the bulk acoustic wave filter 100. Figure 3 is a schematic diagram of the cross-sectional structure of another bulk acoustic wave filter provided by an embodiment of the present invention. As shown in Figure 3, the bulk acoustic wave filter 100 also includes a protective layer 50 located on the side of the metal cover 10 away from the substrate 20. The protective layer 50 includes a curing glue or epoxy resin glue sealing material, which further improves the sealing protection effect of the substrate 10 and the resonator setting area 11, and improves the working reliability of the bulk acoustic wave filter 100.

The technical solution of the present invention is to provide an input pad, an output pad and a plurality of BAW resonators electrically connected between the input pad and the output pad in a resonator setting area in a BAW filter, so that a radio frequency signal input to the input pad can be resonated and filtered by the BAW resonator and then output to the output pad. In addition, by providing a packaging substrate and a metal cover electrically connected to the ground end of the packaging substrate, the substrate is located in a containing space formed by a side wall metal layer and a bottom metal layer. During the operation of the BAW filter, the side wall metal layer or the bottom metal layer forms an inductive coupling with the resonator setting area to reduce the electromagnetic coupling effect between the input pad and the output pad, improve the out-of-band suppression on the left and right sides of the passband, and improve the working reliability of the BAW filter.

Optionally, Figure 4 is a schematic diagram of the cross-sectional structure of another BAW filter provided in an embodiment of the present invention, and Figure 5 is a schematic diagram of the top view structure of another substrate provided in an embodiment of the present invention. Referring to Figures 4 and 5, the BAW filter 100 also includes a peripheral area 22 located on the surface of the substrate 20 facing away from the bottom metal layer 12; the peripheral area 22 surrounds the resonator setting area 21, and the peripheral area 22 is provided with a metal structure 26, the metal structure 26 includes a connecting portion 261 and an opening portion 262, the connecting portion 261 is disconnected at the opening portion 262, and the connecting portion 261 is electrically connected to the ground terminal GND.

The connection part 261 includes metal materials such as copper or iron, and can be set according to actual needs, which is not specifically limited here. The opening part 262 is not provided with metal materials, so the connection part 261 is disconnected at the opening part 262.

Specifically, when an RF signal is input to the input pad 23, electromagnetic coupling will be generated between the input pad 23 and the output pad 24, thereby generating parasitic capacitance. The input pad 23 will also generate parasitic capacitance with the connecting portion 261 in the peripheral area 22 near the input pad 23, and the output pad 24 will also generate parasitic capacitance with the connecting portion 261 in the peripheral area 22 near the output pad 24, thereby causing the out-of-band suppression of the passband of the bulk acoustic wave filter 100 to deteriorate to varying degrees. Since the connecting portion 261 is grounded, the connecting portion 261 can introduce a parasitic inductance, which can be coupled with the parasitic capacitance in the resonator setting area 11, thereby further suppressing the coupling between the input pad 23 and the output pad 24 and improving the out-of-band suppression. In addition, by setting the metal structure 26 to include an opening portion 262, the capacitive coupling between the connecting portion 261 and the input pad 23 or the output pad 24 is weakened, and the electromagnetic coupling effect between the input port 23 and the output port 24 is improved, so as to improve the out-of-band suppression on the left and right sides of the passband and improve the working reliability of the bulk acoustic wave filter.

It should be noted that FIG6 is a passband performance curve diagram of a comparative example and an embodiment provided by the present invention, FIG7 is a structural schematic diagram of a BAW resonator in the prior art, FIG8 is a cross-sectional structural schematic diagram of a BAW resonator in the prior art, and FIG9 is a cross-sectional structural schematic diagram of another BAW resonator in the prior art. Referring to FIG4 and FIG6-9, the structure of the BAW filter corresponding to comparative example 1 in FIG6 can refer to FIG7, and the BAW filter in FIG7 is not provided with a metal structure 26 and a metal cover 10; the structure of the BAW filter corresponding to comparative example 2 can refer to FIG8, and the BAW filter in FIG8 includes a metal structure 26, and the metal structure 26 includes a connecting portion 261 and an opening portion; the structure of the BAW filter corresponding to comparative example 3 can refer to FIG9, and FIG. The BAW filter in 9 includes a metal structure 26 and a metal cover 10, and the metal structure 26 includes a connecting portion 261 and an opening portion, and the metal cover 10 is not electrically connected to the ground terminal GND; the structure of the BAW filter corresponding to Example 1 can refer to Figure 4, and it can be seen from Figure 6 that when the metal cover 10 and the metal structure 26 are simultaneously provided in the BAW filter 100, and the metal structure 26 includes a connecting portion 261 and an opening portion, the connecting portion 261 is electrically connected to the ground terminal GND, and the metal cover 10 is not electrically connected to the ground terminal GND, the parasitic inductance generated by the metal structure 26 and the resonator setting area 21 can be coupled with the parasitic capacitance generated by the resonator setting area 21, but the resonator setting area 21 will generate a new parasitic capacitance with the metal cover 10, resulting in the deterioration of the out-of-band suppression of the passband. By setting the connection part 261 to be electrically connected to the ground terminal GND, and the metal cover 10 to be electrically connected to the ground terminal GND, so that the metal cover 10 and the connection part 261 are coupled with the resonator setting area 21 at the same time to generate parasitic inductance, the out-of-band suppression on the right side of the passband can be improved by 40db, and the out-of-band suppression on the left side of the passband can be improved by 10db. At the same time, the insertion loss within the passband is less affected, thereby improving the working reliability of the bulk acoustic wave filter.

It can be understood that the above description only takes the example that the metal cover 10 is directly electrically connected to the ground terminal GND, and the connecting part 261 is directly electrically connected to the ground terminal GND. In an optional embodiment, Figure 10 is a schematic diagram of the cross-sectional structure of another bulk acoustic wave filter provided in an embodiment of the present invention. As shown in Figure 10, the metal cover 10 is electrically connected to the ground terminal GND through the connecting part 261.

Specifically, a conductive material such as tin paste can be coated on the peripheral area 22 of the connecting portion 261 near the sidewall metal layer 11 to electrically connect the metal cover 10 to the connecting portion 261, and then electrically connect the metal cover 10 to the ground terminal GND through the connecting portion 261, so as to change the electromagnetic coupling effect of the metal cover 10, the connecting portion 261 and the resonator setting area 21, thereby improving the out-of-band suppression of the passband and improving the working reliability of the bulk acoustic wave filter.

It should be noted that Figure 11 is a schematic diagram of the cross-sectional structure of another bulk acoustic wave filter provided by the present invention, and Figure 12 is a passband performance curve diagram of another comparative example and embodiment provided by the present invention. Referring to Figures 7, 8, 10-12, the structure of the bulk acoustic wave filter corresponding to comparative example 1 in Figure 12 can refer to Figure 7, and the bulk acoustic wave filter in Figure 7 is not provided with a metal structure 26 and a metal cover 10; the structure of the bulk acoustic wave filter corresponding to comparative example 2 in Figure 12 can refer to Figure 8, and the bulk acoustic wave filter in Figure 8 includes a metal structure 26, and the metal structure 26 includes a connecting portion 261 and an opening portion; the structure of the bulk acoustic wave filter corresponding to embodiment 2 in Figure 12 can refer to Figure 10, and the structure of the bulk acoustic wave filter corresponding to embodiment 3 in Figure 12 can refer to Figure 11, the bulk acoustic wave filter in Figure 11 includes a metal structure 26 and a metal cover 10, the metal structure 26 includes a connecting portion 261 and an opening portion, the connecting portion 261 and the metal cover 10 are electrically connected to the ground terminal GND respectively, and the connecting portion 261 is electrically connected to the metal cover 10; as can be seen from Figure 12, by setting the connecting portion 261 to be electrically connected to the ground terminal GND, and the metal cover 10 to be electrically connected to the ground terminal GND through the connecting portion 261, the parasitic inductance generated by the metal cover 10 and the connecting portion 261 being coupled with the resonator setting area 21 at the same time is adjusted, so that the out-of-band suppression on the right side of the passband can be improved by 45db, and the out-of-band suppression on the left side of the passband can be improved by 15db, and at the same time, the insertion loss in the passband is less affected, thereby improving the working reliability of the bulk acoustic wave filter.

Optionally, referring to FIG. 10 , the BAW filter 100 further includes a conductive structure 13 , and the conductive structure 13 is electrically connected between the metal cover 10 and the connecting portion 261 .

The conductive structure 13 includes metal wires, conductive through holes or conductive columns, etc. The material of the conductive structure 13 includes conductive materials such as copper or tungsten, which can be set according to actual needs and is not specifically limited here.

Specifically, a conductive structure 13 is provided between the metal cover 10 and the connecting part 261 so that the ground signal received by the connecting part 261 can be transmitted to the metal cover 10 through the conductive structure 13, thereby improving the inductive coupling effect of the metal cover 10 and the connecting part 261 on the resonator setting area 21, improving the out-of-band suppression of the passband, and improving the working reliability of the bulk acoustic wave resonator.

Optionally, FIG13 is a schematic cross-sectional structure diagram of another BAW filter provided in an embodiment of the present invention. As shown in FIG13 , the BAW filter 100 further includes an adhesive layer 40 , and the metal cover 10 is bonded to the substrate 20 via the adhesive layer 40 .

The bonding layer 20 includes materials such as silicon oxide, silicon nitride or aluminum oxide, and can be configured according to actual needs, which is not specifically limited here.

Specifically, by providing an adhesive layer 40 between the metal cover 10 and the substrate 20 , the metal cover 10 is bonded to the substrate 20 through the adhesive layer 40 , thereby improving the adhesion firmness and stability of the metal cover 10 and the substrate 20 , and improving the service life of the BAW filter 100 .

Optionally, Figure 14 is a schematic cross-sectional structure diagram of another BAW filter provided in an embodiment of the present invention. As shown in Figure 14, the conductive structure 13 penetrates the adhesive layer 40, and the two ends of the conductive structure 13 are in contact with the sidewall metal layer 11 and the connecting portion 261 respectively.

Specifically, the distance between the sidewall metal layer 11 located on the side of the connecting portion 261 away from the resonator setting area 21 is shorter, and a conductive structure 13 penetrating the adhesive layer 40 can be set in this shorter distance area. The conductive structure 13 may include a metal wire to reduce the setting length of the metal wire and save materials.

Optionally, Figure 15 is a schematic diagram of the cross-sectional structure of another bulk acoustic wave filter provided in an embodiment of the present invention. As shown in Figure 15, the conductive structure 13 passes through the substrate 20 and the bonding layer 40, and the two ends of the conductive structure 13 are electrically connected to the bottom metal layer 12 and the connecting portion 261, respectively.

Specifically, the conductive structure 13 including a conductive through hole or a conductive column that penetrates the adhesive layer 40 of the substrate 20 is provided to improve the stability and reliability of the ground signal transmitted from the connection portion 261 to the bottom metal layer 12 .

It should be noted that Figure 16 is a schematic diagram of the cross-sectional structure of a bulk acoustic wave filter provided by the present invention, Figure 17 is a passband performance curve diagram of another comparative example and an embodiment provided by the present invention, and Figure 18 is a passband performance curve diagram of a comparative example and an embodiment provided by the present invention. Referring to Figures 7, 8, 15-18, the structure of the bulk acoustic wave filter corresponding to comparative example 1 in Figure 17 can refer to Figure 7, and the bulk acoustic wave filter in Figure 7 is not provided with a metal structure 26 and a metal cover 10; the structure of the bulk acoustic wave filter corresponding to comparative example 2 in Figure 17 can refer to Figure 8, and the bulk acoustic wave filter in Figure 8 includes a metal structure 26, and the metal structure 26 includes a connecting portion 261 and an opening portion; the structure of the bulk acoustic wave filter corresponding to embodiment 4 in Figure 17 can refer to Figure 15; the structure of the bulk acoustic wave filter corresponding to embodiment 5 in Figure 17 can refer to Figure 16, and the bulk acoustic wave filter in Figure 16 includes a metal structure 26 and The metal cover 10 and the metal structure 26 include a connecting portion 261 and an opening portion, the connecting portion 261 and the metal cover 10 are electrically connected to the ground terminal GND respectively, and the connecting portion 261 is electrically connected to the metal cover 10 through a conductive structure 13 that penetrates the substrate 20 and the bonding layer 40; as shown in FIG17 , by setting a conductive structure 13 that penetrates the substrate 20 and the bonding layer 40, so that the connecting portion 261 is electrically connected to the metal cover through the conductive structure 13, so as to improve the stability and reliability of the connecting portion 261 providing the grounding electrical signal to the metal cover 10, so as to improve the parasitic inductance generated by the coupling between the connecting portion 261 and the metal cover 10 and the resonator setting area 21, so that the out-of-band suppression on the right side of the passband can be improved by 30db, and the out-of-band suppression on the left side of the passband can be improved by 5db~15db. While improving the out-of-band suppression of the passband, as shown in FIG18 , the insertion loss in the passband can also be improved, thereby improving the working reliability of the bulk acoustic wave filter.

In an optional embodiment, referring to FIG1 , the thickness of the sidewall metal layer 11 and/or the bottom metal layer 12 of the metal cover 10 is d; wherein d ≥ 2 μm, so as to improve the left and right out-of-band suppression of the passband, so as to improve the working reliability of the BAW filter. On the premise that the thickness d of the sidewall metal layer 11 and/or the bottom metal layer 12 is greater than or equal to 2 μm, the thickness d of the sidewall metal layer 11 and/or the bottom metal layer 12 can be set to a thinner thickness according to actual needs, so as to reduce the overall weight of the BAW filter 100, make the BAW filter 100 lighter and thinner as a whole, and reduce the production cost at the same time.

It should be noted that when the BAW filter 100 operates in different environments, the difference in thickness between the sidewall metal layer 11 and the bottom metal layer 12 in the metal cover 10 has different coupling effects on the resonator setting 21. At this time, according to the actual application environment, a BAW filter in which only the bottom metal layer 12 is set to have a thickness greater than or equal to 2 microns can be selected, or a BAW filter in which only the sidewall metal layer 11 is set to have a thickness greater than or equal to 2 microns can be selected, or a BAW filter in which the thickness of both the bottom metal layer 12 and the sidewall metal layer 11 are set to be greater than or equal to 2 microns can be selected to adapt to different usage requirements.

Optionally, Figure 19 is a schematic diagram of a top view structure of another substrate provided in an embodiment of the present invention. As shown in Figure 19, the BAW filter 100 also includes at least two conductors 27; the conductors 27 are located in the resonator setting area 21, and the conductors 27 are electrically connected to the connecting portion 261 and the ground terminal GND respectively.

Among them, the conductor 27 includes metal materials such as gold, silver or copper, and the shape of the conductor 27 can be set according to actual needs. Exemplarily, the conductor 27 includes a cylindrical metal pad or a metal implant ball, etc., and can also be other shapes, which are not specifically limited here.

Specifically, by providing at least two conductors 27, a ground signal can be transmitted in a partial connection portion 261 that forms a current loop with the two conductors 27, thereby coupling the partial connection portion 261 with the input pad 23 or the output pad 24 to generate a parasitic inductance, thereby suppressing the degree of deterioration of the passband suppression caused by the parasitic capacitance between the input pad 23 and the output pad 24, improving the out-of-band suppression of the passband, and enhancing the working reliability of the BAW filter 100.

It can be understood that FIG. 19 only shows the arrangement of the resonator arrangement area 21 including two conductors 27. On the premise that the number of conductors 27 is greater than 2, the number of conductors 27 can also be other, which is not specifically limited here. In addition, the specific arrangement position of the conductor 27 in the resonator arrangement area 21 can be set according to actual needs. When the resonator arrangement area 21 includes two conductors 27, FIG. 19 only shows that one of the conductors 27 is located near the central axis of the resonator arrangement area 21 along the X direction and close to the side of the connecting portion 161, and the other conductor 27 is located on the side of the resonator arrangement area 21 away from the input pad 23 along the X direction. By adjusting the position of the conductor 27 in the resonator arrangement area 21, the length of the current path formed by the conductor 27 in the connecting portion 261 can be adjusted, and then the coupling degree of the connecting portion 21 with the input pad 23 or the output pad 24 can be adjusted, so that the bulk acoustic wave filter 100 produces different out-of-band suppression effects.

It is necessary, referring to Fig. 19, that the resonator setting area 21 further includes a ground pad 28, and the ground pad 28 is electrically connected to a part of the BAW resonator 25, and the ground pad 28 can be electrically connected to the ground terminal GND in the package substrate 30 to receive a ground signal. In an optional embodiment, the ground pad 28 can be reused as a conductor 27 to increase the area of the BAW resonator 25 in the resonator setting area 21, increase the number of BAW resonators 25, and improve the filtering effect of the BAW filter.

Based on the same inventive concept, an embodiment of the present invention further provides an electronic device, which includes a bulk acoustic wave filter provided by any embodiment of the present invention. The electronic device has the technical features of the bulk acoustic wave filter provided by the embodiment of the present invention and can achieve the beneficial effects of the bulk acoustic wave filter provided by the embodiment of the present invention. The similarities can be referred to the above description of the bulk acoustic wave filter provided by the embodiment of the present invention, and will not be repeated here.

Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims (10)

1. A bulk acoustic wave filter, comprising:

The metal cover comprises a side wall metal layer and a bottom metal layer, and the side wall metal layer and the bottom metal layer form an accommodating space;

a substrate positioned in the accommodating space, wherein one side surface of the substrate facing away from the bottom metal layer comprises a resonator arrangement area; the resonator setting area is provided with an input pad, an output pad and a plurality of bulk acoustic wave resonators electrically connected between the input pad and the output pad;

the packaging substrate is positioned on one side of the substrate, which is away from the bottom metal layer, and comprises a grounding end, and the metal cover is electrically connected with the grounding end.

2. The bulk acoustic wave filter of claim 1, further comprising: the peripheral area is positioned on one side surface of the substrate, which is away from the bottom metal layer;

The peripheral region surrounds the resonator arrangement region, the peripheral region is provided with a metal structure, the metal structure comprises a connecting portion and an opening portion, the connecting portion is disconnected at the opening portion, and the connecting portion is electrically connected with the grounding end.

3. The bulk acoustic wave filter according to claim 2, wherein the metal cap is electrically connected to the ground terminal through the connection portion.

4. A bulk acoustic wave filter according to claim 3, further comprising: a conductive structure;

the conductive structure is electrically connected between the metal cover and the connecting part.

5. The bulk acoustic wave filter of claim 4, further comprising: a bonding layer;

The metal cover is attached to the substrate through the adhesive layer.

6. The bulk acoustic wave filter of claim 5, wherein the conductive structure extends through the adhesive layer and both ends of the conductive structure are in contact with the sidewall metal layer and the connection portion, respectively.

7. The bulk acoustic wave filter of claim 5, wherein the conductive structure extends through the substrate and the adhesive layer, and wherein both ends of the conductive structure are electrically connected to the bottom metal layer and the connection portion, respectively.

8. The bulk acoustic wave filter according to claim 1, wherein the sidewall metal layer and/or the bottom metal layer of the metal cap has a thickness d;

Wherein d is not less than 2 μm.

9. The bulk acoustic wave filter of claim 2, further comprising: at least two electrical conductors;

The electric conductor is located in the resonator setting area, and is electrically connected with the connecting portion and the grounding end respectively.

10. An electronic device comprising a bulk acoustic wave filter as claimed in any one of claims 1-9.