Filter and electronic equipment

Abstract

The invention discloses a filter and electronic equipment. The filter comprises a piezoelectric substrate; the interdigital transducer is formed on the first side of the piezoelectric substrate; the wire is formed on the first side of the piezoelectric substrate; the first insulating layer is formed on the first side of the piezoelectric substrate and covers the wires, a first opening and a second opening are formed in the first insulating layer, the interdigital transducers are exposed out of the first opening, the second opening is adjacent to the first opening, and part of the wires are exposed out of the second opening; the second insulating layer is formed on the side, away from the piezoelectric substrate, of the first insulating layer and seals the side, away from the piezoelectric substrate, of the first opening, a third opening is formed in the second insulating layer, and the third opening is communicated with the second opening; the third insulating layer is formed on the side, away from the first insulating layer, of the second insulating layer, a fourth opening is formed in the third insulating layer, and the fourth opening is communicated with the third opening; and the leading-out terminals are formed in the second opening, the third opening and the fourth opening. The filter and the electronic equipment are small in size and low in cost.

Description

Technical Field

[0001] The present application relates to the technical field of radio frequency filtering, and in particular to a filter and an electronic device. Background Art

[0002] With the development of wireless communication technology, the competition in the consumer market has intensified, which has promoted the development of filters such as surface acoustic wave (SAW) filters towards miniaturization and low cost.

[0003] In the related art, the filter substrate is usually provided with multiple traces, interdigital transducers (IDTs) and multiple contact pads (also called pads), the traces on the substrate are connected to the contact pads, and the contact pads are led out to the device surface through lead terminals. The presence of multiple contact pads will occupy a considerable area of ​​the substrate, and the contact pads are usually arranged at a position far away from the cavity where the interdigital transducers are located, resulting in a larger filter volume and higher cost.

[0004] Therefore, improvements are needed to at least partially solve the above problems. Summary of the invention

[0005] A series of simplified concepts are introduced in the Summary of the Invention, which will be further described in detail in the Detailed Description of the Invention. The Summary of the Invention does not mean to attempt to define the key features and essential technical features of the claimed technical solution, nor does it mean to attempt to determine the scope of protection of the claimed technical solution.

[0006] In order to at least partially solve the above problem, according to a first aspect of the present invention, a filter is provided, comprising:

[0007] Piezoelectric substrate;

[0008] an interdigital transducer formed on a first side of the piezoelectric substrate;

[0009] A wiring line formed on a first side of the piezoelectric substrate and connected to the interdigital transducer;

[0010] a first insulating layer, formed on a first side of the piezoelectric substrate and covering the wiring, wherein a first opening and a second opening are provided in the first insulating layer, the first opening and the second opening both penetrate the first insulating layer, the first opening exposes the interdigital transducer, and the second opening is adjacent to the first opening and exposes a portion of the wiring;

[0011] a second insulating layer formed on a side of the first insulating layer away from the piezoelectric substrate and closing a side of the first opening away from the piezoelectric substrate, wherein a third opening penetrating the second insulating layer is provided in the second insulating layer, and the third opening is connected to the second opening;

[0012] a third insulating layer, the third insulating layer being formed on a side of the second insulating layer away from the first insulating layer, the third insulating layer being provided with a fourth opening penetrating the third insulating layer, the fourth opening being connected to the third opening;

[0013] Lead-out terminals are formed in the second opening, the third opening, and the fourth opening, and are connected to the wiring.

[0014] Exemplarily, a projection of the second opening on the piezoelectric substrate and a projection of the third opening on the piezoelectric substrate are both located inside a projection of the fourth opening on the piezoelectric substrate.

[0015] Illustratively, a projection of the second opening on the piezoelectric substrate coincides with a projection of the third opening on the piezoelectric substrate.

[0016] Exemplarily, a projection of the second opening on the piezoelectric substrate and a projection of the third opening on the piezoelectric substrate are both rectangular;

[0017] The projection of the fourth opening on the piezoelectric substrate is circular.

[0018] Illustratively, a projection of the fourth opening on the piezoelectric substrate partially overlaps with a projection of the first opening on the piezoelectric substrate.

[0019] Exemplarily, the first insulating layer, the second insulating layer and the third insulating layer are all polyimide film layers.

[0020] Exemplarily, the lead terminal includes a metal column and a solder ball;

[0021] The metal pillar is formed in the second opening, the third opening and the fourth opening;

[0022] The solder ball is located at a side of the metal column away from the piezoelectric substrate.

[0023] Exemplarily, the piezoelectric substrate includes a supporting substrate layer and a piezoelectric layer located on the supporting substrate layer, and the first side of the piezoelectric substrate is a side of the piezoelectric layer away from the supporting substrate layer.

[0024] Exemplarily, the piezoelectric substrate includes a supporting substrate layer, a fourth insulating layer located on the supporting substrate layer, and a piezoelectric layer located on a side of the fourth insulating layer away from the supporting substrate layer, and the first side of the piezoelectric substrate is a side of the piezoelectric layer away from the supporting substrate layer.

[0025] According to a second aspect of the present invention, there is provided an electronic device comprising the filter as described above.

[0026] According to the filter and electronic device of the present invention, on the one hand, the lead-out terminals are formed in the second opening, the third opening and the fourth opening, and are directly connected to the wiring to realize the lead-out of the wiring, so that a separate contact pad may not be provided on the substrate, which can effectively reduce the area occupied; on the other hand, the lead-out terminals may be provided at a position closer to the cavity where the interdigital transducer is located, so that the filter structure is more compact, thereby effectively reducing the volume and reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The following drawings of the present application are hereby used as part of the present application for understanding the present application. The drawings show the embodiments of the present application and their descriptions, and are used to explain the device and principle of the present application. In the drawings,

[0028] Figure 1 is a schematic structural diagram of a filter according to an embodiment of the present application;

[0029] Figure 2 for Figure 1 Schematic cross-sectional view at AA in the middle.

[0030] Description of reference numerals:

[0031] 100 - piezoelectric substrate, 101 - supporting substrate layer, 102 - piezoelectric layer, 110 - interdigital transducer, 120 - routing, 130 - first insulating layer, 131 - first opening, 132 - second opening, 140 - second insulating layer, 141 - third opening, 150 - third insulating layer, 151 - fourth opening, 160 - lead terminal, 161 - metal column, 162 - solder ball. DETAILED DESCRIPTION

[0032] In the following description, a large number of specific details are provided to provide a more thorough understanding of the present application. However, it is apparent to those skilled in the art that the present application can be implemented without one or more of these details. In other examples, in order to avoid confusion with the present application, some technical features well known in the art are not described.

[0033] It should be understood that the present application can be implemented in different forms and should not be construed as being limited to the embodiments presented herein. On the contrary, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present application to those skilled in the art. In the accompanying drawings, the sizes and relative sizes of layers and regions may be exaggerated for clarity. The same reference numerals throughout represent the same elements.

[0034] It should be understood that although the terms first, second, third, etc. can be used to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the present application, the first element, component, region, layer or part discussed below can be represented as a second element, component, region, layer or part.

[0035] Spatially relative terms such as "under", "beneath", "below", "under", "above", "above", etc., may be used herein for convenience of description to describe the relationship of one element or feature to other elements or features shown in the figures. It should be understood that the spatially relative terms are intended to encompass different orientations of the device in use and operation in addition to the orientation shown in the figures.

[0036] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be limiting of the present application. When used herein, the singular forms "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "consisting of" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0037] Embodiments of the invention are described herein with reference to cross-sectional views as schematic diagrams of ideal embodiments (and intermediate structures) of the present application. Thus, variations in the shapes shown due to, for example, manufacturing techniques and / or tolerances can be expected. Therefore, embodiments of the present application should not be limited to the specific shapes shown herein, but include shape deviations due to, for example, manufacturing. Therefore, what is shown in the figures is schematic in nature, and their shapes are not intended to display the actual shape of the device and are not intended to limit the scope of the present application.

[0038] Refer to the attached Figure 1 , 2The filter according to an embodiment of the present application is exemplarily described. Exemplarily, the filter may be a surface acoustic wave filter. The filter includes a piezoelectric substrate 100, an interdigital transducer 110, a trace 120, a first insulating layer 130, a second insulating layer 140, a third insulating layer 150, and a lead terminal 160.

[0039] In the present embodiment, the piezoelectric substrate 100 includes a supporting substrate layer 101 and a piezoelectric layer 102 located on the supporting substrate layer 101. The supporting substrate layer 101 is used to support the piezoelectric layer 102. Exemplarily, the material of the supporting substrate layer 101 can be sapphire, silicon (Si), germanium (Ge), silicon germanium (SiGe), carbon silicon (SiC), carbon germanium silicon (SiGeC), indium arsenide (InAs), gallium arsenide (GaAs), indium phosphide (InP) or other III / V compound semiconductors. The piezoelectric layer 102 is formed of a piezoelectric material, and the piezoelectric material can be a piezoelectric single crystal, a piezoelectric ceramic or a piezoelectric film. Exemplarily, the piezoelectric single crystal can be quartz, lithium niobate, lithium tantalate, etc., the piezoelectric ceramic can be a barium titanate ceramic, a lead zirconate titanate ceramic, etc., and the piezoelectric film can be a zinc oxide film, aluminum nitride, a gallium nitride film, etc.

[0040] In some embodiments, the piezoelectric substrate 100 includes a supporting substrate layer 101, a fourth insulating layer located on the supporting substrate layer 101, and a piezoelectric layer 102 located on a side of the fourth insulating layer away from the supporting substrate layer 101. That is, the piezoelectric substrate 100 may be a piezoelectric on insulator (POI) substrate. Exemplarily, the fourth insulating layer may be a buried oxide layer, a nitride layer, or other suitable dielectric layer.

[0041] In some embodiments, the piezoelectric substrate 100 may be a substrate formed of only a piezoelectric single crystal or a piezoelectric ceramic.

[0042] An interdigital transducer 110 (IDT) is formed on the first side of the piezoelectric substrate 100. The interdigital transducer 110 includes a series of interdigitated electrode fingers (arranged like fingers crossing each other). The interdigital transducer 110 can be formed by depositing a metal layer on the first side of the piezoelectric substrate 100 and patterning the metal layer. The material of the interdigital transducer 110 may include at least one of aluminum, copper, gold, silver, platinum and titanium. It should be noted that the first side of the piezoelectric substrate 100 is the side of the piezoelectric layer 102 away from the supporting substrate layer 101.

[0043] A trace 120 (also called a trace) is formed on the first side of the piezoelectric substrate 100 and connected to the IDT 110. Exemplarily, after the IDT 110 is formed on the first side of the piezoelectric substrate 100, a patterned photoresist layer may be formed on the first side of the piezoelectric substrate 100 by a photolithography process, and then, the patterned photoresist layer is used as a mask to form the trace 120 on the first side of the piezoelectric substrate 100 by a metal deposition process, and the trace 120 is connected to the IDT 110 to realize electrical lead-out of the IDT 110. Exemplarily, the material of the trace 120 may include at least one of aluminum, copper, gold, silver, platinum and titanium.

[0044] The first insulating layer 130 is formed on the first side of the piezoelectric substrate 100 and covers the trace 120. The first insulating layer 130 is provided with a first opening 131 and a second opening 132, and the first opening 131 and the second opening 132 both penetrate the first insulating layer 130. It should be noted that the first opening 131 and the second opening 132 are both openings inside the first insulating layer 130 rather than at the edge, that is, the first opening 131 and the second opening 132 are not gaps at the edge of the first insulating layer 130. The first opening 131 exposes the interdigital transducer 110, and the second opening 132 is adjacent to the first opening 131 and exposes part of the trace 120. It should be noted that the proximity mentioned here means that the minimum distance between the two is less than a suitable distance threshold, for example, less than 10μm, 20μm, 40μm, 80μm, 100μm or other suitable distance thresholds.

[0045] Exemplarily, the first insulating layer 130 may be a polyimide film layer or other suitable organic film layer. Specifically, after the IDT 110 and the trace 120 are formed on the first side of the piezoelectric substrate 100, a polyimide film layer may be attached to the first side of the piezoelectric substrate 100 by a film attaching device, the polyimide film layer covers the IDT 110 and the trace 120, and then a first opening 131 and a second opening 132 are formed on the polyimide film layer by a photolithography process or an etching process (e.g., a dry etching process), the first opening 131 exposes the IDT 110, the second opening 132 is adjacent to the first opening 131, and exposes a portion of the trace 120.

[0046] The second insulating layer 140 is formed on a side of the first insulating layer 130 away from the piezoelectric substrate 100, and closes a side of the first opening 131 away from the piezoelectric substrate 100. That is, the second insulating layer 140, the first insulating layer 130 and the piezoelectric substrate 100 together form a cavity at the first opening 131, and the interdigital transducer 110 is located in the cavity. A third opening 141 is provided in the second insulating layer 140, penetrating the second insulating layer 140, and the third opening 141 is connected to the second opening 132. The third opening 141 is an opening inside the second insulating layer 140 rather than at the edge, that is, the third opening 141 is not a gap at the edge of the second insulating layer 140.

[0047] Exemplarily, the second insulating layer 140 may be a polyimide film layer or other suitable organic film layer. Specifically, after the first insulating layer 130 is formed, a polyimide film layer may be attached to the first insulating layer 130 by a film attaching device, the polyimide film layer closes the side of the first opening 131 away from the piezoelectric substrate 100, and then a third opening 141 connected to the second opening 132 is formed on the polyimide film layer by a photolithography process or an etching process (e.g., a dry etching process). In some embodiments, when the first insulating layer 130 is formed, the second opening 132 may not be formed first, but when the second insulating layer 140 is formed, the second opening 132 and the third opening 141 are formed in the first insulating layer 130 and the second insulating layer 140 at one time by a photolithography process or an etching process (e.g., a dry etching process).

[0048] The third insulating layer 150 is formed on a side of the second insulating layer 140 away from the first insulating layer 130. The third insulating layer 150 is provided with a fourth opening 151 penetrating the third insulating layer 150, and the fourth opening 151 is connected to the third opening 141. The fourth opening 151 is an opening inside the third insulating layer 150 rather than at the edge, that is, the fourth opening 151 is not a gap at the edge of the third insulating layer 150.

[0049] Exemplarily, the third insulating layer 150 may be a polyimide film layer or other suitable organic film layer. Specifically, after the second insulating layer 140 is formed, a polyimide film layer may be attached to the second insulating layer 140 by a film attaching device, and then a fourth opening 151 communicating with the third opening 141 may be formed on the polyimide film layer by a photolithography process or an etching process (e.g., a dry etching process).

[0050] Lead terminals 160 are formed in the second opening 132, the third opening 141 and the fourth opening 151. The lead terminals 160 are connected to the traces 120 on the side facing the piezoelectric substrate 100. The traces 120 and the lead terminals 160 can electrically lead the IDT 110 to the outside of the filter.

[0051] In the present embodiment, the lead terminal 160 includes a metal column 161 formed in the second opening 132, the third opening 141 and the fourth opening 151. Exemplarily, the metal column 161 may partially protrude from the side of the third insulating layer 150 away from the piezoelectric substrate 100. The lead terminal 160 also includes a solder ball 162 located on the side of the metal column 161 away from the piezoelectric substrate 100. Exemplarily, the metal column 161 may be a copper column, and the solder ball 162 (Bump, also known as a bump) may be a tin-silver alloy. Specifically, after the third insulating layer 150 is formed, the metal column 161 and the solder layer located on the side of the metal column 161 away from the piezoelectric substrate 100 may be formed in the second opening 132 and the third opening 141 by an electrochemical plating process, and then the solder layer may be made into a solder ball 162 by a reflow process.

[0052] According to the filter of the embodiment of the present application, on the one hand, the lead-out terminal 160 is formed in the second opening 132, the third opening 141 and the fourth opening 151, and is directly connected to the wiring 120 to realize the lead-out of the wiring 120, so that a separate contact pad may not be provided on the substrate, which can effectively reduce the area occupied by the contact pad on the substrate, making the filter structure more compact, and further effectively reducing the volume of the filter and reducing the production cost of the filter. On the other hand, in the present embodiment, part of the lead-out terminals 160 located in the second opening 132 and the third opening 141 do not need to be directly connected to external devices (for example, there is no need to consider the setting of solder balls). Therefore, the cross-sectional area of ​​part of the lead-out terminals 160 located in the second opening 132 and the third opening 141 in the direction perpendicular to the piezoelectric substrate 100 can be smaller than the cross-sectional area of ​​part of the lead-out terminals 160 located in the fourth opening 151 in the direction perpendicular to the piezoelectric substrate 100. Therefore, the second opening 132 and the third opening 141 can be arranged at a position closer to the first opening 131 (that is, closer to the cavity where the interdigital transducer 110 is located), that is, the lead-out terminal 160 as a whole can be arranged at a position closer to the first opening 131 (that is, closer to the cavity where the interdigital transducer 110 is located). Therefore, the structure of the filter can be more compact, thereby effectively reducing the volume of the filter and reducing the production cost of the filter.

[0053] In this embodiment, the projection of the second opening 132 on the piezoelectric substrate 100 is rectangular, that is, the second opening 132 is in the thickness direction of the piezoelectric substrate 100 (that is, Figure 1 The cross section of the second opening 132 in the vertical direction (in the middle and lower directions) is rectangular. Exemplarily, the length direction of the rectangle is consistent with the extension direction of the trace 120, and the projection of the second opening 132 in the thickness direction of the piezoelectric substrate 100 completely falls on the trace 120. Through the above arrangement, the contact area between the part of the lead terminal 160 formed in the second opening 132 and the trace 120 can be increased, thereby improving the electrical connection performance.

[0054] The projection of the third opening 141 on the piezoelectric substrate 100 is rectangular, that is, the cross section of the third opening 141 in the thickness direction of the piezoelectric substrate 100 is rectangular. Exemplarily, the projection of the third opening 141 on the piezoelectric substrate 100 coincides with the projection of the second opening 132 on the piezoelectric substrate 100. In some embodiments, the overlap of the projection of the second opening 132 on the piezoelectric substrate 100 may be located inside the projection of the third opening 141 on the piezoelectric substrate 100, that is, the projection of the third opening 141 on the piezoelectric substrate 100 completely covers the projection of the second opening 132 on the piezoelectric substrate 100.

[0055] The projection of the fourth opening 151 on the piezoelectric substrate 100 is rectangular, that is, the cross section of the fourth opening 151 in the thickness direction of the piezoelectric substrate 100 is circular. By setting the cross section of the fourth opening 151 in the thickness direction of the piezoelectric substrate 100 to be circular, the solder ball 162 in the lead terminal 160 can be formed into a relatively ideal bump shape, so that it can be better combined with other devices to form a good electrical connection.

[0056] In this embodiment, the projection of the second opening 132 on the piezoelectric substrate 100 and the projection of the third opening 141 on the piezoelectric substrate 100 are both located inside the projection of the fourth opening 151 on the piezoelectric substrate, that is, the projection of the fourth opening 151 on the piezoelectric substrate completely covers the projection of the second opening 132 on the piezoelectric substrate 100 and the projection of the third opening 141 on the piezoelectric substrate 100. On the one hand, the lead terminal 160 away from the side of the piezoelectric substrate 100 can form a larger area solder ball 162, thereby improving its connection effect with external devices; on the other hand, since the cross-sectional area of ​​the part of the lead terminal 160 located in the second opening 132 and the third opening 141 in the direction perpendicular to the piezoelectric substrate 100 is smaller than the cross-sectional area of ​​the part of the lead terminal 160 located in the fourth opening 151 in the direction perpendicular to the piezoelectric substrate 100, and the fourth opening 151 with a larger cross-sectional area does not need to avoid the first opening 131 (that is, closer to the cavity where the interdigital transducer 110 is located), the second opening 132 and the third opening 141 can form a larger area solder ball 162, thereby improving its connection effect with external devices; on the other hand, since the cross-sectional area of ​​the part of the lead terminal 160 located in the second opening 132 and the third opening 141 in the direction perpendicular to the piezoelectric substrate 100 is smaller than the cross-sectional area of ​​the part of the lead terminal 160 located in the fourth opening 151 in the direction perpendicular to the piezoelectric substrate 100, and the fourth opening 151 with a larger cross-sectional area does not need to avoid the first opening 131 (that is, closer to the cavity where the interdigital transducer 11 132 and the third opening 141 can be arranged at a position closer to the first opening 131 (that is, closer to the cavity where the interdigital transducer 110 is located), that is, the lead terminal 160 as a whole can be arranged at a position closer to the first opening 131 (that is, closer to the cavity where the interdigital transducer 110 is located), and accordingly, the wiring 120 in this embodiment can be arranged at a position closer to the first opening 131 (that is, closer to the cavity where the interdigital transducer 110 is located) relative to the filter in the prior art, so that the structure of the filter can be more compact, thereby effectively reducing the volume of the filter and reducing the production cost of the filter.

[0057] See attached Figure 2In this embodiment, the projection of the fourth opening 151 on the piezoelectric substrate 100 partially overlaps with the projection of the first opening 131 on the piezoelectric substrate 100. Since the third insulating layer 150 does not need to close the first opening 131, the fourth opening 151 does not need to avoid the first opening 131, and the projection of the fourth opening 151 on the piezoelectric substrate 100 can partially overlap with the projection of the first opening 131 on the piezoelectric substrate 100. Through the above arrangement, the lead terminal 160 can be made closer to the first opening 131 as a whole (that is, closer to the cavity where the interdigital transducer 110 is located), and accordingly, the trace 120 can be arranged at a position closer to the first opening 131, so that the structure of the filter can be more compact, thereby effectively reducing the volume of the filter and reducing the production cost of the filter.

[0058] In some other embodiments, the filter further includes a passivation layer, which is formed on the first side of the piezoelectric substrate 100 and covers the interdigital transducer 110 and the trace 120. The first insulating layer 130 is formed on the side of the passivation layer away from the piezoelectric substrate 100, and the position of the passivation layer corresponding to the second opening 132 is also correspondingly provided with an opening that exposes a portion of the trace 120. Exemplarily, the material of the passivation layer can be at least one of silicon oxide, silicon nitride, aluminum nitride, and aluminum oxide.

[0059] The present application also provides an electronic device, which includes the filter as described above. The electronic device can be a personal computer, a mobile terminal such as a smart phone, a media player, a navigation device, an electronic game device, a game controller, a tablet computer, a wearable device, an anti-access electronic system, a POS terminal, a medical device, a flight simulator, etc.

[0060] Although example embodiments have been described herein with reference to the accompanying drawings, it should be understood that the above example embodiments are merely exemplary and are not intended to limit the scope of the present application to this. Those of ordinary skill in the art may make various changes and modifications therein without departing from the scope and spirit of the present application. All these changes and modifications are intended to be included within the scope of the present application as required by the appended claims.

[0061] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are only schematic, for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another device, or some features can be ignored or not executed.

[0062] In the description provided herein, a large number of specific details are described. However, it is understood that the embodiments of the present application can be practiced without these specific details. In some instances, well-known methods, structures and techniques are not shown in detail so as not to obscure the understanding of this description.

[0063] Similarly, it should be understood that in order to streamline the present application and help understand one or more of the various inventive aspects, in the description of the exemplary embodiments of the present application, the various features of the present application are sometimes grouped together into a single embodiment, figure, or description thereof. However, the method of the present application should not be interpreted as reflecting the following intention: the claimed application requires more features than the features clearly stated in each claim. More specifically, as reflected in the corresponding claims, the inventive point is that the corresponding technical problem can be solved with features less than all the features of a single disclosed embodiment. Therefore, the claims following the specific embodiment are hereby explicitly incorporated into the specific embodiment, wherein each claim itself serves as a separate embodiment of the present application.

[0064] It will be understood by those skilled in the art that, except for mutually exclusive features, all features disclosed in this specification (including the accompanying claims, abstracts and drawings) and all processes or units of any method or device disclosed in this specification may be combined in any combination. Unless otherwise expressly stated, each feature disclosed in this specification (including the accompanying claims, abstracts and drawings) may be replaced by an alternative feature that provides the same, equivalent or similar purpose.

[0065] In addition, those skilled in the art will appreciate that, although some embodiments described herein include certain features included in other embodiments but not other features, the combination of features of different embodiments is meant to be within the scope of the present application and form different embodiments. For example, in the claims, any one of the claimed embodiments can be used in any combination.

[0066] It should be noted that the above-mentioned embodiments illustrate rather than limit the invention and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims.

Claims

1. A filter, characterized in that: include: Piezoelectric substrate; an interdigital transducer formed on a first side of the piezoelectric substrate; A wiring line formed on a first side of the piezoelectric substrate and connected to the interdigital transducer; a first insulating layer, formed on a first side of the piezoelectric substrate and covering the wiring, wherein a first opening and a second opening are provided in the first insulating layer, the first opening and the second opening both penetrate the first insulating layer, the first opening exposes the interdigital transducer, and the second opening is adjacent to the first opening and exposes a portion of the wiring; a second insulating layer formed on a side of the first insulating layer away from the piezoelectric substrate and closing a side of the first opening away from the piezoelectric substrate, wherein a third opening penetrating the second insulating layer is provided in the second insulating layer, and the third opening is connected to the second opening; a third insulating layer, the third insulating layer being formed on a side of the second insulating layer away from the first insulating layer, the third insulating layer being provided with a fourth opening penetrating the third insulating layer, the fourth opening being connected to the third opening; Lead-out terminals are formed in the second opening, the third opening, and the fourth opening, and are connected to the wiring.

2. The filter according to claim 1, characterized in that A projection of the second opening on the piezoelectric substrate and a projection of the third opening on the piezoelectric substrate are both located inside a projection of the fourth opening on the piezoelectric substrate.

3. The filter according to claim 2, characterized in that A projection of the second opening on the piezoelectric substrate coincides with a projection of the third opening on the piezoelectric substrate.

4. The filter according to claim 2, characterized in that The projection of the second opening on the piezoelectric substrate and the projection of the third opening on the piezoelectric substrate are both rectangular; The projection of the fourth opening on the piezoelectric substrate is circular.

5. The filter according to any one of claims 2 to 4, characterized in that: A projection of the fourth opening on the piezoelectric substrate partially overlaps with a projection of the first opening on the piezoelectric substrate.

6. The filter according to claim 1, characterized in that The first insulating layer, the second insulating layer and the third insulating layer are all polyimide film layers.

7. The filter according to claim 1, characterized in that The lead-out terminal includes a metal column and a solder ball; The metal pillar is formed in the second opening, the third opening and the fourth opening; The solder ball is located at a side of the metal column away from the piezoelectric substrate.

8. The filter according to claim 1, characterized in that The piezoelectric substrate includes a supporting substrate layer and a piezoelectric layer located on the supporting substrate layer. The first side of the piezoelectric substrate is a side of the piezoelectric layer away from the supporting substrate layer.

9. The filter according to claim 1, characterized in that The piezoelectric substrate includes a supporting substrate layer, a fourth insulating layer located on the supporting substrate layer, and a piezoelectric layer located on a side of the fourth insulating layer away from the supporting substrate layer. The first side of the piezoelectric substrate is a side of the piezoelectric layer away from the supporting substrate layer.

10. An electronic device, characterized in that: The filter comprises the filter according to any one of claims 1 to 9.

Images