CN114448379A

CN114448379A - Acoustic device packaging structure

Info

Publication number: CN114448379A
Application number: CN202210088699.6A
Authority: CN
Inventors: 王阳; 吴洋洋; 曹庭松; 陆彬
Original assignee: Beijing Super Material Information Technology Co ltd
Current assignee: Beijing Super Material Information Technology Co ltd
Priority date: 2022-01-25
Filing date: 2022-01-25
Publication date: 2022-05-06

Abstract

The invention provides a surface acoustic wave filter device, which comprises a piezoelectric substrate, a first electrode and a second electrode, wherein the piezoelectric substrate is provided with an upper surface and a lower surface which are opposite; a filter circuit including a plurality of surface acoustic wave resonators connected by a signal wire, the surface acoustic wave resonators and the signal wire being formed on an upper surface of the piezoelectric substrate; at least one ground conductor formed on the upper surface of the piezoelectric substrate and electrically connected to at least one of the plurality of surface acoustic wave resonators; at least a portion of the ground conductor is provided with a ground serration structure that is electrostatically coupled to the signal conductor. The invention optimizes and improves the conventional grounding wire and signal wire, and realizes the surface acoustic wave filter device with high reliability through electrostatic protection.

Description

Acoustic device packaging structure

Technical Field

The invention relates to a filter used in wireless communication equipment, in particular to a surface acoustic wave filter device with antistatic discharge capacity.

Background

In a high-frequency front-end module of a mobile communication device such as a mobile phone, a surge (ESD: electrostatic discharge, frequency of about 300 MHz) enters from an antenna. For this reason, the anti-surge element is generally disposed between the antenna terminal and the ground, and the prior art generally solves the ESD problem by disposing an inductive element or disposing a nonlinear resistor. However, the anti-surge element provided directly to the antenna end has a fundamental problem of increasing the loss of the transmission or reception signal.

Surface acoustic wave filters (SAW) are widely used as core components for frequency signal processing up to the GHz band. In particular, since the SAW filter has excellent characteristics such as mass productivity, selectivity, stability, etc., it can be applied to a wide range of applications in RF mobile communication. Currently, SAW filters tend to continue to be miniaturized in size and are therefore produced in chip scale package type (CSP). The more miniaturized semiconductor integrated circuits are, the more sensitive to electrostatic discharge pulses and are more susceptible to physical damage from the high voltages and currents generated by electrostatic discharge pulses. Therefore, it is very urgent and necessary to develop a SAW filter against electrostatic discharge.

Disclosure of Invention

In order to solve the related problems in the prior art, the present invention provides a surface acoustic wave filter device, including: a piezoelectric substrate having opposing upper and lower surfaces; a filter circuit including a plurality of surface acoustic wave resonators connected by a signal wire, the surface acoustic wave resonators and the signal wire being formed on an upper surface of the piezoelectric substrate; at least one ground conductor formed on the upper surface of the piezoelectric substrate and electrically connected to at least one of the plurality of surface acoustic wave resonators; at least a portion of the ground conductor is provided with a ground serration structure that is electrostatically coupled to the signal conductor.

Further, at least a portion of the signal conductor is provided with a signal saw tooth structure, and the ground saw tooth structure is electrostatically coupled with the signal saw tooth structure.

The grounding sawtooth structure comprises a grounding protrusion, the signal sawtooth structure comprises a signal protrusion, and the grounding protrusion and the signal protrusion are arranged in a right-to-right mode.

Wherein, the angle between the inner included angle theta 1 of the grounding protrusion and the inner included angle theta 2 of the signal protrusion is smaller than 80 degrees.

Further, a minimum distance L between an outer edge of the ground protrusion and an outer edge of the signal protrusion is set to be less than 150 um.

The minimum distance L between the outer edge of the ground protrusion and the outer edge of the signal protrusion is set to be less than 10 um.

Wherein the ground serration structure has a ground protrusion width d1, the signal serration structure has a signal protrusion width d2, and the ground protrusion width d1 is similar in value to the signal protrusion width d 2.

Wherein the ground protrusion width d1 or the signal protrusion width d2 is greater than a wavelength of a surface acoustic wave excited by one or more of the surface acoustic wave resonators.

Further, the surface acoustic wave filter device further includes: an input terminal and an output terminal, the filter circuit coupled to the input and output terminals and the ground conductor to provide input signals to and output signals from the surface acoustic wave device.

Wherein the signal sawtooth structure is disposed between the input terminal and the filter circuit.

Wherein the signal sawtooth structure is disposed between the output terminal and the filter circuit.

Still further, the signal saw tooth structure is disposed between the surface acoustic wave resonators.

Wherein the filtering means is a band pass filter.

Still further, the present invention provides a method of manufacturing a surface acoustic wave filter device, including: providing a piezoelectric substrate, wherein the piezoelectric substrate is provided with an upper surface and a lower surface which are oppositely arranged, a filter circuit is formed on the upper surface of the piezoelectric substrate, the filter circuit comprises a plurality of surface acoustic wave resonators, and the surface acoustic wave resonators are connected through signal wires; forming at least one ground conductor on an upper surface of the piezoelectric substrate, the ground conductor being electrically connected to at least one of the plurality of surface acoustic wave resonators; a ground saw tooth structure is formed on at least a portion of the ground conductor and a signal saw tooth structure is formed on at least a portion of the signal conductor such that the ground saw tooth structure is electrostatically coupled to the signal saw tooth structure.

According to the surface acoustic wave filter device of the present invention, a high suppression degree or a high isolation degree can be provided within a predetermined frequency band by electrostatic protection, so that the operational stability of the surface acoustic wave filter device is improved, the safety performance thereof is improved, and the service life thereof is prolonged.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:

fig. 1 is a schematic structural diagram of a surface acoustic wave filter device according to a first embodiment of the present invention.

Fig. 2 is a circuit topology diagram of a surface acoustic wave filter device according to a first embodiment of the invention.

Fig. 3 is a schematic circuit diagram of a surface acoustic wave filter device according to a first embodiment of the invention.

Fig. 4 is a schematic plan view of a surface acoustic wave filter device according to a second embodiment of the present invention.

Fig. 5 is a schematic plan view of a surface acoustic wave filter device according to a third embodiment of the present invention.

Fig. 6 is a schematic plan view of a saw-tooth structure in a surface acoustic wave filter device according to a third embodiment of the present invention.

Fig. 7 is a schematic plan view of a surface acoustic wave filter device according to a fourth embodiment of the present invention.

Fig. 8 is a flowchart of a process for manufacturing a surface acoustic wave filter device according to still another embodiment of the present invention.

Reference numerals:

1. 10, 100, 110-piezoelectric substrate

2-filter circuit

11. 12, 13, 14, 21, 22, 23, 101, 102, 103, 104, 201, 202, 203, 111, 112, 113, 114, 211, 212, 213-surface acoustic wave resonator

3. 5, 40, 41, 42-signal line

4. 43, 44, 45-ground conductor

32. 34, 302, 304, 312, 316, 314-ground serration structures

301. 303, 311, 313, 315-signal sawtooth structure

3001-ground lug

3002-Signal projection

Detailed Description

So that the manner in which the above recited objects, features and advantages of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are illustrated in the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited by the specific embodiments disclosed below.

Example one

As shown in fig. 1 and 2, the present embodiment provides a surface acoustic wave filter device including: a piezoelectric substrate 1 having opposing upper and lower surfaces; a filter circuit 2 including a plurality of surface acoustic wave resonators connected by

signal wires

3 and 5, the surface acoustic wave resonators and the signal wires being formed on an upper surface of the piezoelectric substrate 1; at least one ground conductor 4 is also formed on the upper surface of the piezoelectric substrate 1 and electrically connected to at least one of the plurality of surface acoustic wave resonators. The surface acoustic wave filter device further includes: input and output terminals (labeled "In", "Out", respectively), the filter circuit 2 being coupled to the input and output terminals and the ground conductor to provide input signals to and output signals from the surface acoustic wave device to implement a bandpass function. According to different connection modes of the internal circuits of the filter circuit 2, the invention can also realize high-pass and low-pass functions. At least a part of the ground conductor 4 is provided with a ground serration which is electrostatically coupled to the

signal conductors

3, 5.

The filter circuit 2 includes a plurality of surface acoustic wave resonators S1, S2, S3, S4, P1, P2, and P3, as shown in fig. 3, wherein S1, S2, S3, and S4 are connected in series between the input and output terminals, and are series resonators, and P1, P2, and P3 are connected in parallel between the series line and the ground, and are parallel resonators. The series resonators are electrically connected to each other through

signal wires

40, 41, and 42, the parallel resonators are electrically connected to each other through

ground conductors

43, 44, and 45, and the ground conductor 4 includes the

ground conductors

43, 44, and 45. At least a part of the

ground conductors

43, 44, 45 is provided with a ground serration structure which is electrostatically coupled to the

signal conductors

3, 5, and may be electrostatically coupled to the

signal conductors

40, 41, 42.

The surface acoustic wave resonator can be SAW, XBAR and the like, and the surface acoustic wave filter device is packaged in a flip chip or WLP packaging mode, so that sealing materials such as resin and the like or a substrate surface are prevented from being in contact with IDT electrodes of the filter circuit, and further sensitive IDT electrodes are prevented from being influenced. Wherein the circuit substrate is a commonly used circuit board such as a PCB or other form of multi-layer wiring circuit board, but the invention is not limited thereto.

Example two

As shown in fig. 4, which is a schematic plan view of the surface acoustic wave filter device of the present embodiment, the present embodiment is similar to the first embodiment, and the grounding saw-tooth structure will be described in detail in the present embodiment. A surface acoustic wave filter device comprising: a piezoelectric substrate 10 having opposing upper and lower surfaces; a filter circuit includes a plurality of surface

acoustic wave resonators

11, 12, 13, 14, 21, 22, 23, wherein 11, 12, 13, 14 are connected in series between input and output terminals and are series resonators, 21, 22, 23 are connected in parallel between a series line and grounds GND1, GND2 and are parallel resonators, and GND1, GND2 are provided in common and constitute a part of a ground conductor. The series resonators are electrically connected to each other through a signal wire, and the parallel resonators are electrically connected to each other through a ground conductor.

The

ground serration structures

32 and 34 are disposed on at least a portion of the ground conductors GND1 and GND2, wherein the

ground serration structures

32 and 34 may be disposed on at least a portion of the ground conductors GND1 and GND2, as shown in the present embodiment, or disposed on all the trace portions of the ground conductors GND1 and GND2, so as to obtain better electrostatic protection effect, but may bring about complexity of the manufacturing process and increase of the cost, but the present invention is not limited thereto. In this embodiment, the grounding saw tooth structure 32 is electrostatically coupled to the signal conductor of the input terminal, and the grounding saw tooth structure 34 is electrostatically coupled to the signal conductor of the output terminal. Of course, any one of the grounding saw-

tooth structures

32 and 34 can be optionally selected, and is electrostatically coupled to the input end or the output end, and if all the trace portions of the grounding conductors GND1 and GND2 are provided with the grounding saw-tooth structures, the grounding conductor is electrostatically coupled to as many signal wires as possible, which also belongs to the design idea of the present invention. Wherein the

ground serration structures

32, 34 comprise ground projections disposed opposite the signal conductors of the input or output terminals as shown in fig. 4. The isolation of the surface acoustic wave filter device is important to the performance of the surface acoustic wave filter device, the interference of external electric signals, magnetic field signals and the like can cause interference to the filter, and static electricity generated by an internal static electricity source can also affect the frequency characteristic and the safety performance of a product.

EXAMPLE III

Fig. 5 is a schematic plan view of a surface acoustic wave filter device according to a third embodiment, which is similar to the second embodiment, but is a design further improved from the second embodiment. A surface acoustic wave filter device comprising: a piezoelectric substrate 100 having opposing upper and lower surfaces; a filter circuit includes a plurality of surface

acoustic wave resonators

101, 102, 103, 104, 201, 202, and 203, wherein 101, 102, 103, and 104 are connected in series between input and output terminals, and are series resonators, 201, 202, and 203 are connected in parallel between a series line and grounds GND3 and GND4, and are parallel resonators, and GND3 and GND4 are provided in common, and constitute a part of a ground conductor, as shown in fig. 5 (a). In the present embodiment, the

parallel resonators

201, 202, and 203 may be connected to the respective grounds GND3, GND8, and GND4, and the potentials of GND3, GND8, and GND4 may be the same, and they may constitute a part of the ground conductor, as shown in fig. 5 (b). Some of the parallel resonators may be connected in common and the remaining parallel resonators may be connected to another ground to minimize signal interference, but the invention is not limited thereto. The series resonators are electrically connected to each other through a signal wire, and the parallel resonators are electrically connected to each other through a ground conductor.

The ground saw

tooth structures

302 and 304 are disposed on at least a portion of the ground conductors GND3 and GND4, wherein the ground saw

tooth structures

302 and 304 may be disposed on at least a portion of the ground conductors GND3 and GND4, as shown in the present embodiment, or disposed on all the trace portions of the ground conductors GND3 and GND4, so as to obtain better electrostatic protection effect, but this may cause complexity of the manufacturing process and increase of the cost, but the present invention is not limited thereto.

Unlike the second embodiment, at least a portion of the signal conductor is provided with a signal saw tooth structure, illustratively an input signal saw tooth structure 301 and an output signal saw tooth structure 303. The grounding sawtooth structure 302 is electrostatically coupled with the input end signal sawtooth structure 301, the grounding sawtooth structure 304 is electrostatically coupled with the output end signal sawtooth structure 303, and in the specific design, the grounding sawtooth structure 302 is just opposite to the protruding structure of the input end signal sawtooth structure 301, and the grounding sawtooth structure 304 is just opposite to the protruding structure of the output end signal sawtooth structure 303. Of course, any one of the grounding saw-

tooth structures

302 and 304 may be optionally selected, or electrostatically coupled to the signal saw-tooth structure at the input end, or electrostatically coupled to the signal saw-tooth structure at the output end, and if all the trace portions of the grounding conductors GND3 and GND4 are provided with the grounding saw-tooth structures, the signal wires may also be correspondingly provided with as many signal saw-tooth structures as possible, so that the grounding saw-tooth structures are electrostatically coupled to as many signal saw-tooth structures as possible, which also belongs to the design idea of the present invention.

The ground saw

tooth structures

302 and 304 include a plurality of ground protrusions 3001, the signal saw

tooth structures

301 and 303 include a plurality of signal protrusions 3002, and the ground protrusions 3001 are disposed opposite to the signal protrusions 3002, as shown in fig. 6. In addition, the inner included angle of the ground protrusion 3001 is set to θ 1, the inner included angle of the signal protrusion 3002 is set to θ 2, the angles θ 1 and θ 2 may be set to an obtuse angle, or may be set to a right angle or an acute angle, and the ground protrusion 3001 may have an inner included angle of a different value, and the signal protrusion 3002 may have an inner included angle of a different value. The present invention preferably sets the angle θ 1 and the angle θ 2 to less than 80 ° based on the best electrostatic discharge effect. Meanwhile, considering that the different pitches of the ground protrusion 3001 and the signal protrusion 3002 will affect the discharging effect, the present invention sets the minimum pitch L between the outer edge of the ground protrusion 3001 and the outer edge of the signal protrusion 3002 to be less than 150um, preferably less than 10um, to obtain the best electrostatic discharging effect.

In this embodiment, the ground saw tooth structure has a ground protrusion width d1, the signal saw tooth structure has a signal protrusion width d2, and the ground protrusion width d1 is similar to the signal protrusion width d2, so that the filter signal terminal and the ground terminal have the most complete discharging effect when the electrostatic strength is similar. As to the specific values of d1 or d2, without further limitation, the ground serration structures may have different values of ground protrusion width and the signal serration structures may have different values of signal protrusion width. In the present invention, the value of d1 or d2 is set to be greater than the wavelength of the surface acoustic wave excited by one or more of the surface acoustic wave resonators to further reduce the undesirable acoustic wave coupling between the different resonators.

Example four

As shown in fig. 7, a schematic plan view of a surface acoustic wave filter device according to a fourth embodiment is similar to the third embodiment, but is a design further improved from the third embodiment. A surface acoustic wave filter device comprising: a piezoelectric substrate 110 having opposing upper and lower surfaces; a filter circuit includes a plurality of surface

acoustic wave resonators

111, 112, 113, 114, 211, 212, 213, wherein 111, 112, 113, 114 are connected in series between input and output terminals and are series resonators, 211, 212, 213 are connected in parallel between a series line and a ground GND5, GND6, GND7, respectively, are parallel resonators, and GND5, GND6, GND7 have the same potential and constitute a part of a ground conductor. The series resonators are electrically connected to each other through a signal wire, and the parallel resonators are electrically connected to each other through a ground conductor.

At least a part of any one of the ground conductors GND5, GND6 and GND7 is provided with a ground saw tooth structure, for example, a ground saw tooth structure 312 may be provided at least a part of the ground conductor GND5, a ground saw tooth structure 316 may be provided at least a part of the ground conductor GND6, and a ground saw tooth structure 314 may be provided at least a part of the ground conductor GND7, wherein the ground saw tooth structures may also be provided at all trace portions of the ground conductor to obtain a better electrostatic protection effect. At least a portion of the signal conductor is provided with a signal saw tooth structure, for example, the signal saw tooth structure may be provided between the input terminal and the filter circuit, the signal saw tooth structure may also be provided between the output terminal and the filter circuit, or the signal saw tooth structure may also be provided between the surface acoustic wave resonators. For example, the signal saw tooth structure 311 is an input end signal saw tooth structure 311, the signal saw tooth structure 313 is an output end signal saw tooth structure 315, and the signal saw tooth structure is arranged on a middle serial or parallel line, wherein the signal saw tooth structure can also be arranged on all the trace portions of the signal conducting wire, so as to better cooperate with the grounding saw tooth structure to obtain a better electrostatic protection effect. In the specific design, the protruding structure of the ground saw-tooth structure 312 is opposite to the protruding structure of the input-end signal saw-tooth structure 311, the protruding structure of the ground saw-tooth structure 316 is opposite to the protruding structure of the filter circuit internal line signal saw-tooth structure 315, and the protruding structure of the ground saw-tooth structure 314 is opposite to the protruding structure of the output-end signal saw-tooth structure 313. If all the routing portions of the ground conductors GND5, GND6 and GND7 are provided with the ground saw-tooth structures, the signal wires can also be correspondingly provided with the signal saw-tooth structures as many as possible, so that the ground saw-tooth structures are electrostatically coupled with the signal saw-tooth structures as many as possible, and the design idea of the invention also belongs to. As a modified implementation manner, similar to the second and third embodiments, this embodiment may also selectively provide the grounding saw tooth structure and the signal saw tooth structure, which are coupled electrostatically, at any one or two of the input end, the output end, and the signal transmission portion of the filtering apparatus according to the actual situation of the electrostatic source, for example, at the input end and the output end of the filtering apparatus, or at the input end and the signal transmission portion, and so on, which belong to the design idea of the present invention.

The fifth embodiment provides an exemplary technical solution related to the manufacturing process of the surface acoustic wave filter device:

EXAMPLE five

The present invention also provides a method of manufacturing a surface acoustic wave filter device, as shown in fig. 8, including the steps of: providing a piezoelectric substrate, wherein the piezoelectric substrate is provided with an upper surface and a lower surface (a1) which are oppositely arranged, a filter circuit is formed on the upper surface of the piezoelectric substrate, the filter circuit comprises a plurality of surface acoustic wave resonators, the surface acoustic wave resonators are connected through signal wires, and at least one part of the signal wires form a signal sawtooth structure (a 2); forming at least one ground conductor on an upper surface of the piezoelectric substrate, at least a portion of the ground conductor forming a ground saw tooth structure, the ground conductor being electrically connected to at least one of the plurality of surface acoustic wave resonators (a 3).

When the surface acoustic wave filter device is manufactured, the electrostatic coupling of the grounding sawtooth structure and the signal sawtooth structure obviously reduces the electrostatic interference when the surface acoustic wave filter device works, improves the safety, and further reduces the undesirable acoustic coupling among different resonators, thereby integrally improving the reliability and the working stability of the surface acoustic wave filter device.

In the present invention, the terms "first", "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance; the term "plurality" means two or more. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A surface acoustic wave filter device comprising: a piezoelectric substrate having opposing upper and lower surfaces;

a filter circuit including a plurality of surface acoustic wave resonators connected by a signal wire, the surface acoustic wave resonators and the signal wire being formed on an upper surface of the piezoelectric substrate;

at least one ground conductor formed on the upper surface of the piezoelectric substrate and electrically connected to at least one of the plurality of surface acoustic wave resonators; the method is characterized in that:

at least a portion of the ground conductor is provided with a ground serration structure that is electrostatically coupled to the signal conductor.

2. The surface acoustic wave filter device according to claim 1, wherein:

at least a portion of the signal conductor is provided with a signal saw tooth structure, and the ground saw tooth structure is electrostatically coupled with the signal saw tooth structure.

3. The surface acoustic wave filter device according to claim 2, wherein:

4. A surface acoustic wave filter device according to claim 3, wherein:

the angle between the inner included angle theta 1 of the grounding protrusion and the inner included angle theta 2 of the signal protrusion is smaller than 80 degrees.

5. The surface acoustic wave filter device according to claim 3, wherein:

the minimum distance L between the outer edge of the ground protrusion and the outer edge of the signal protrusion is set to be less than 150 um.

6. The surface acoustic wave filter device according to claim 5, wherein:

7. The surface acoustic wave filter device according to claim 2, wherein: the ground serration structure has a ground protrusion width d1, the signal serration structure has a signal protrusion width d2, and the ground protrusion width d1 is similar in value to the signal protrusion width d 2.

8. The surface acoustic wave filter device according to claim 7, wherein:

the ground protrusion width d1 or the signal protrusion width d2 is greater than the wavelength of a surface acoustic wave excited by one or more of the surface acoustic wave resonators.

9. The surface acoustic wave filter device according to claim 2, further comprising:

an input terminal and an output terminal, the filter circuit coupled to the input and output terminals and the ground conductor to provide input signals to and output signals from the surface acoustic wave device.

10. The surface acoustic wave filter device according to claim 9, wherein:

the signal sawtooth structure is arranged between the input terminal and the filter circuit.

11. The surface acoustic wave filter device according to claim 2 or 10, wherein:

the signal sawtooth structure is arranged between the output terminal and the filter circuit.

12. The surface acoustic wave filter device according to claim 2 or 10, wherein:

the signal sawtooth structure is arranged between the surface acoustic wave resonators.

13. The surface acoustic wave filter device according to claim 2 or 10, wherein:

the filtering means is a band pass filter.

14. A method of manufacturing a surface acoustic wave filter device, comprising:

providing a piezoelectric substrate having an upper surface and a lower surface disposed opposite to each other,

forming a filter circuit on the upper surface of the piezoelectric substrate, wherein the filter circuit comprises a plurality of surface acoustic wave resonators which are connected through a signal wire;

forming at least one ground conductor on an upper surface of the piezoelectric substrate, the ground conductor being electrically connected to at least one of the plurality of surface acoustic wave resonators;

a ground saw tooth structure is formed on at least a portion of the ground conductor and a signal saw tooth structure is formed on at least a portion of the signal conductor such that the ground saw tooth structure is electrostatically coupled to the signal saw tooth structure.