A surface acoustic wave filter and a packaging method thereof

Abstract

The application discloses a surface acoustic wave filter and a packaging method thereof. The surface acoustic wave filter comprises a filter chip and a packaging layer. The filter chip is provided with a transmission electrode. The back surface of the filter chip is provided with an input pin, an output pin and a ground pin. The filter chip is provided with a first through hole, a second through hole and a third through hole extending along the thickness direction. The first through hole is provided with a first conductive part. The second through hole is provided with a second conductive part. The third through hole is provided with a third conductive part. The input pin is electrically connected with the input electrode through the first conductive part. The output pin is electrically connected with the output electrode through the second conductive part. The ground pin is electrically connected with the ground electrode through the third conductive part. The functional area is arranged in the cavity formed between the packaging layer and the filter chip. The surface acoustic wave filter has the advantages of small thickness and low cost.

Description

Technical Field

[0001] This invention relates to the field of filter technology, specifically to a surface acoustic wave filter and its packaging method. Background Technology

[0002] Surface acoustic wave (SAW) filters utilize the piezoelectric properties of piezoelectric materials to filter electrical signals through electro-acoustic-electro-electric conversion. They are primarily used in the field of mobile communications.

[0003] Surface acoustic wave (SAW) filters typically employ chip-scale packaging (CSP) or wafer-level packaging (WLP). These packaging processes primarily involve fabricating metal patterns on a wafer, then creating metal balls on pads of a packaging substrate. The wafer is flip-chip mounted onto the packaging substrate, and the input, output, and ground electrodes on the wafer are soldered to the metal balls on the pads. After soldering, the filter chip and packaging substrate are molded and sealed together. Finally, the wafer is diced to form the SAW filter. In related technologies, the thickness of the SAW filter is equal to the sum of the packaging substrate thickness, solder ball height, wafer thickness, and molding thickness, resulting in a relatively thick overall thickness, which is detrimental to the miniaturization design of RF systems. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] Therefore, embodiments of the present invention propose a surface acoustic wave filter with small thickness and low cost.

[0006] The embodiments of the present invention also propose a packaging method for a surface acoustic wave filter that has a simple process and low manufacturing cost.

[0007] The surface acoustic wave (SAW) filter of this invention includes a filter chip and a packaging layer. The front side of the filter chip has a functional area, which includes an input electrode, an output electrode, and a ground electrode. The back side of the filter chip has an input pin, an output pin, and a ground pin. The filter chip has a first through-hole, a second through-hole, and a third through-hole extending along its thickness direction. A first conductive element is disposed in the first through-hole, a second conductive element is disposed in the second through-hole, and a third conductive element is disposed in the third through-hole. The input pin is electrically connected to the input electrode through the first conductive element, the output pin is electrically connected to the output electrode through the second conductive element, and the ground pin is electrically connected to the ground electrode through the third conductive element. The packaging layer is disposed on the front side of the filter chip, and a cavity is formed between the packaging layer and the filter chip. The functional area is disposed within the cavity.

[0008] The thickness of the surface acoustic wave filter in this embodiment of the invention is the sum of the wafer thickness and the packaging layer thickness. Compared with related technologies, it eliminates the packaging substrate structure, reduces the thickness of the packaging substrate and the height of the solder balls, which not only greatly reduces the overall thickness of the surface acoustic wave filter, which is beneficial to the miniaturization design of the radio frequency system, but also saves materials and has a lower cost.

[0009] Therefore, the surface acoustic wave filter of the present invention has advantages such as small thickness and low cost.

[0010] In some embodiments, the filter chip has a first groove on its back side, the first through hole communicates with the first groove, a portion of the input pin is located inside the first groove, and the other portion of the input pin is located outside the first groove; and / or the filter chip has a second groove on its back side, the second groove communicates with the second through hole, a portion of the output pin is located inside the second groove, and the other portion of the output pin is located outside the second groove; and / or the filter chip has a third groove on its back side, the third groove communicates with the third through hole, a portion of the ground pin is located inside the third groove, and the other portion of the ground pin is located outside the third groove.

[0011] In some embodiments, the first groove is disposed in the thickness direction of the filter chip corresponding to the first through hole, the second groove is disposed in the thickness direction of the filter chip corresponding to the second through hole, and the third groove is disposed in the thickness direction of the filter chip corresponding to the third through hole.

[0012] In some embodiments, the front side of the filter chip also has a soldering area, which surrounds the functional area. The surface acoustic wave filter further includes an annular solder joint disposed within the soldering area. The encapsulation layer and the filter chip are soldered together via the solder joint.

[0013] In some embodiments, the welded component is a welded sheet.

[0014] In some embodiments, the functional area is provided with a metal pattern, the metal pattern having the input electrode, the output electrode and the ground electrode, the metal pattern including a plurality of resonators, each of the resonators being provided with an interdigital transducer, and the plurality of resonators being connected in series and / or in parallel.

[0015] In some embodiments, at least one of the resonators has the ground electrode.

[0016] In some embodiments, the encapsulation layer has a clearance groove with an opening facing the filter chip, and the cavity is formed between the clearance groove and the front side of the filter chip.

[0017] In some embodiments, the following steps are included:

[0018] A first through-hole, a second through-hole, and a third through-hole extending along the thickness direction are formed on the wafer, and a first conductive element is disposed in the first through-hole, a second conductive element is disposed in the second through-hole, and a third conductive element is disposed in the third through-hole.

[0019] An input electrode, an output electrode, and a ground electrode are fabricated on the first surface of the wafer, and the input electrode, the output electrode, and the ground electrode are electrically connected to the first conductive element, the second conductive element, and the third conductive element, respectively.

[0020] An input pin, an output pin, and a ground pin are fabricated on the second surface of the wafer, and the input pin, the output pin, and the ground pin are electrically connected to the first conductive element, the second conductive element, and the third conductive element, respectively.

[0021] The wafer is cut to form a filter chip, the surface of the filter chip corresponding to the first surface forms the front side of the filter chip, and the surface of the filter chip corresponding to the second surface forms the back side of the filter chip.

[0022] The encapsulation layer is fixed to the front side of the filter chip.

[0023] The packaging method for the surface acoustic wave (SAW) filter of this invention includes the following process flow: fabricating through-holes on a wafer, filling the through-holes with metal material, fabricating metal patterns, wafer dicing, and sealing. Those skilled in the art will understand that the packaging method for SAW filters in related technologies involves fabricating metal patterns on a wafer, processing a packaging substrate, pad ball placement, wafer dicing, chip flip bonding, and molding sealing. The processing of the packaging substrate and other processes are generally performed in different factories, requiring transfer to another plant for manufacturing. The packaging method for the SAW filter of this invention eliminates the need for a packaging substrate, thus eliminating the steps of packaging substrate processing, pad ball placement, and chip flip bonding. This significantly shortens the manufacturing process of the SAW filter of this invention, saves materials, and reduces manufacturing costs.

[0024] Therefore, the packaging method of the surface acoustic wave filter in this embodiment of the invention has the advantages of simple process and low manufacturing cost.

[0025] In some embodiments, the encapsulation layer is welded and fixed to the filter chip. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a surface acoustic wave filter according to an embodiment of the present invention.

[0027] Figure 2 This is a schematic diagram of the surface acoustic wave filter without the encapsulation layer according to an embodiment of the present invention.

[0028] Figure 3 This is a schematic diagram of the back side of the filter chip of the surface acoustic wave filter according to an embodiment of the present invention.

[0029] Figure 4 This is a cross-sectional view of the surface acoustic wave filter according to an embodiment of the present invention.

[0030] Figure label:

[0031] Surface acoustic wave filter 100;

[0032] Filter chip 1; Functional area 101; Soldering area 102; First through hole 103; Second through hole 104; Third through hole 105; First groove 106; Second groove 107; Third groove 108;

[0033] Metal pattern 2; Input electrode 201; Output electrode 202; Ground electrode 203; Resonator 204; Interdigital transducer 205;

[0034] Input pin 301; Output pin 302;

[0035] First conductive element 401; Second conductive element 402;

[0036] Encapsulation layer 5; clearance groove 501;

[0037] Welded component 6. Detailed Implementation

[0038] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0039] The technical solution of this application is described in detail below with reference to the accompanying drawings.

[0040] like Figures 1 to 4As shown, the surface acoustic wave filter 100 of this embodiment includes a filter chip 1 and a packaging layer 5. The front side of the filter chip 1 has a functional area 101, within which are an input electrode 201, an output electrode 202, and a ground electrode 203. The back side of the filter chip 1 has an input pin 301, an output pin 302, and a ground pin (not shown in the figure). The filter chip 1 has a first through-hole 103, a second through-hole 104, and a third through-hole 105 extending along its thickness direction. A first conductive element 401 is disposed in the first through-hole 103, a second conductive element 402 is disposed in the second through-hole 104, and a third conductive element (not shown in the figure) is disposed in the third through-hole 105. The input pin 301 is electrically connected to the input electrode 201 through the first conductive element 401, the output pin 302 is electrically connected to the output electrode 202 through the second conductive element 402, and the ground pin is electrically connected to the ground electrode 203 through the third conductive element. The encapsulation layer 5 is disposed on the front side of the filter chip 1, and a cavity is formed between the encapsulation layer 5 and the filter chip 1. The functional area 101 is disposed in the cavity.

[0041] The surface acoustic wave filter 100 of this invention provides leakage protection for the surface acoustic wave filter 100 by providing a first through-hole 103 on the filter chip 1, housing a first conductive element 401 within the first through-hole 103 and electrically connecting it to the input pin 301 and the input electrode 201, respectively. This allows external electrical signals to be transmitted to the functional area 101 for filtering via the input pin 301. A second through-hole 104 on the filter chip 1 provides a second conductive element 402 within the second through-hole 104 and electrically connecting it to the output pin 302 and the output electrode 202, respectively. This allows the filtered electrical signal in the functional area 101 to be transmitted out through the output pin 302. A third through-hole 105 on the filter chip 1 provides a third conductive element within the third through-hole 105 and electrically connecting it to the ground pin and the ground electrode 203, allowing leakage current in the functional area 101 to be transmitted to the ground via the ground pin. By setting an encapsulation layer 5 on the front side of the filter chip 1, the functional area 101 of the filter chip 1 is located in the cavity formed between the encapsulation layer 5 and the filter chip 1, thereby protecting the functional area 101 of the filter chip 1 so that the filter chip 1 can work normally.

[0042] The thickness of the surface acoustic wave filter 100 in this embodiment of the invention is the sum of the wafer thickness and the packaging layer 5 thickness. Compared with related technologies, the packaging substrate structure is eliminated, reducing the thickness of the packaging substrate and the height of the solder balls. This not only greatly reduces the overall thickness of the surface acoustic wave filter 100, which is beneficial for the miniaturization design of the radio frequency system, but also saves materials and has a lower cost.

[0043] Therefore, the surface acoustic wave filter 100 of the present invention has advantages such as small thickness and low cost.

[0044] To make the technical solution of this application easier to understand, the following describes the technical solution of this application further using the example that the thickness direction of the filter chip 1 is consistent with the vertical direction, the length direction of the filter chip 1 is consistent with the horizontal direction, and the width direction of the filter chip 1 is consistent with the front-back direction. The vertical and horizontal directions are as follows: Figures 1 to 4 As shown, the front and back directions are as follows Figures 1 to 3 As shown.

[0045] For example, such as Figure 3 and Figure 4 As shown, the filter chip 1 is positioned with its front side facing upwards. Each of the first through-hole 103, the second through-hole 104, and the third through-hole 105 penetrates the filter chip 1 vertically. A first conductive element 401 is disposed vertically within the first through-hole 103. The upper end of the first conductive element 401 is connected to the input electrode 201 of the functional area 101, and the lower end of the first conductive element 401 is connected to the input pin 301. A second conductive element 402 is disposed vertically within the second through-hole 104. The upper end of the second conductive element 402 is connected to the output electrode 202 of the functional area 101, and the lower end of the second conductive element 402 is connected to the output pin 302. A third conductive element is disposed vertically within the first through-hole 103. The upper end of the third conductive element is connected to the ground electrode 203 of the functional area 101, and the lower end of the third conductive element is connected to the ground pin.

[0046] In some embodiments, a metal pattern 2 is provided in the functional area 101. The metal pattern 2 has an input electrode 201, an output electrode 202 and a ground electrode 203. The metal pattern 2 includes a plurality of resonators 204. Each resonator 204 is provided with an interdigital transducer 205. The plurality of resonators 204 are connected in series and / or in parallel.

[0047] The series and / or parallel connection of multiple resonators 204 can be understood as all of the multiple resonators 204 being connected in series, or all of the multiple resonators 204 being connected in parallel, or multiple resonators 204 being connected in both series and parallel.

[0048] For example, such as Figure 2As shown, the metal pattern 2 within functional area 101 has five resonators 204, namely a first resonator, a second resonator, a third resonator, a fourth resonator, and a fifth resonator. Each resonator 204 is equipped with an interdigital transducer 205. The first, second, and third resonators are arranged sequentially from left to right and are connected in series. The fourth and fifth resonators are located in front of the first resonator, with the fourth resonator to the left of the fifth resonator. The fourth resonator is connected in parallel with the first resonator, and the fifth resonator is connected in parallel with the third resonator. The surface acoustic wave filter 100 of this embodiment of the invention has multiple resonators 204 on its metal pattern, and these resonators are connected in series and parallel, which helps to improve the filtering effect of the surface acoustic wave filter 100 of this embodiment of the invention.

[0049] Optionally, at least one resonator 204 has a ground electrode 203.

[0050] For example, such as Figure 2 As shown, the first resonator 204 is connected to an input electrode 201, the third resonator 204 is connected to an output electrode 202, and the fourth and fifth resonators 204 are both connected to ground electrodes 203. The surface acoustic wave filter 100 of this embodiment of the invention, by providing multiple ground electrodes 203 on the metal pattern 2, can further improve the leakage current protection capability of the surface acoustic wave filter 100.

[0051] In some embodiments, the back of the filter chip 1 is provided with a first groove 106, the first through hole 103 communicates with the first groove 106, a part of the input pin 301 is located inside the first groove 106, and the other part of the input pin 301 is located outside the first groove 106.

[0052] like Figure 3 and Figure 4 As shown, the upper end of the input pin 301 is placed inside the first groove 106 and connected to the lower end of the first conductive element 401, while the lower end of the input pin 301 is placed outside the first groove 106 for connection to the device motherboard. The surface acoustic wave filter 100 of this embodiment of the invention provides a first groove 106 on the back of the filter chip 1, with a portion of the input pin 301 placed inside the first groove 106. When the input pin 301 is subjected to lateral forces in the front-back, left-right, and right directions on the device motherboard, the sidewall of the first groove 106 restricts the input pin 301, preventing it from easily separating from the filter chip 1 due to lateral forces. This enhances the connection strength between the input pin 301 and the filter chip 1, and improves the operational reliability of the surface acoustic wave filter 100 of this embodiment of the invention.

[0053] In some embodiments, the back of the filter chip 1 is provided with a second groove 107, which communicates with the second through hole 104. A portion of the output pin 302 is located inside the second groove 107, and another portion of the output pin 302 is located outside the second groove 107.

[0054] like Figure 3 and Figure 4 As shown, the upper end of the output pin 302 is placed inside the second groove 107 and connected to the lower end of the second conductive element 402, while the lower end of the output pin 302 is placed outside the second groove 107 for connection to the device motherboard. The surface acoustic wave filter 100 of this embodiment of the invention provides a second groove 107 on the back of the filter chip 1, and places a portion of the output pin 302 within the second groove 107. When the output pin 302 is subjected to lateral forces in the front-back, left-right, and right directions on the device motherboard, the groove sidewall of the second groove 107 restricts the output pin 302, preventing it from easily separating from the filter chip 1 due to lateral forces. This enhances the connection strength between the output pin 302 and the filter chip 1, further improving the operational reliability of the surface acoustic wave filter 100 of this embodiment of the invention.

[0055] In some embodiments, the back of the filter chip 1 is provided with a third groove 108, which is connected to a third through hole 105. A portion of the grounding pin is located inside the third groove 108, and the other portion of the grounding pin is located outside the third groove 108.

[0056] The upper end of the grounding pin is placed inside the third groove 108 and connected to the lower end of the third conductive element, while the lower end of the grounding pin is placed outside the third groove 108 for connection to the device motherboard. In this embodiment of the surface acoustic wave filter 100, by providing a third groove 108 on the back of the filter chip 1 and placing a portion of the grounding pin inside the third groove 108, when the grounding pin is subjected to lateral forces in the front-back, left-right, and right directions on the device motherboard, the groove sidewall of the third groove 108 restricts the grounding pin, preventing it from easily separating from the filter chip 1 due to lateral forces. This enhances the connection strength between the grounding pin and the filter chip 1 and improves the operational reliability of the surface acoustic wave filter 100.

[0057] Optionally, each of the grounding electrode 203, grounding pin, third conductive element, third through hole 105 and third groove 108 has multiple components, and the multiple grounding electrodes 203, multiple grounding pins, multiple third conductive elements, multiple third through holes 105 and multiple third grooves 108 correspond to each other one-to-one, and the third conductive element is connected to the corresponding grounding electrode 203 and grounding pin.

[0058] In some implementations, the first groove 106 is provided in the thickness direction of the filter chip 1 corresponding to the first through hole 103, the second groove 107 is provided in the thickness direction of the filter chip 1 corresponding to the second through hole 104, and the third groove 108 is provided in the thickness direction of the filter chip 1 corresponding to the third through hole 105.

[0059] like Figure 3 As shown, the first through hole 103 has a circular cross-section, and the first groove 106 has a rectangular cross-section. The cross-section of the first through hole 103 is perpendicular to the thickness direction of the filter chip 1, and the cross-section of the first groove 106 is perpendicular to the thickness direction of the filter chip 1. The first through hole 103 and the first groove 106 are correspondingly arranged vertically. The second through hole 104 has a circular cross-section, and the second groove 107 has a rectangular cross-section. The cross-section of the second through hole 104 is perpendicular to the thickness direction of the filter chip 1, and the cross-section of the second groove 107 is perpendicular to the thickness direction of the filter chip 1. The second through hole 104 and the second groove 107 are correspondingly arranged vertically. The third through hole 105 has a circular cross-section, and the third groove 108 has a rectangular cross-section. The cross-section of the third through hole 105 is perpendicular to the thickness direction of the filter chip 1, and the cross-section of the third groove 108 is perpendicular to the thickness direction of the filter chip 1. The third through hole 105 and the third groove 108 are correspondingly arranged vertically. The surface acoustic wave filter 100 of this invention has a simple structure and is easy to manufacture by setting a first groove 106 in the thickness direction of the filter chip 1 corresponding to a first through hole 103, a second groove 107 in the thickness direction of the filter chip 1 corresponding to a second through hole 104, and a third groove 108 in the thickness direction of the filter chip 1 corresponding to a third through hole 105.

[0060] In some embodiments, the front side of the filter chip 1 also has a soldering area 102, which surrounds the functional area 101. The surface acoustic wave filter 100 also includes an annular soldering member 6, which is disposed in the soldering area 102. The encapsulation layer 5 is soldered to the filter chip 1 through the soldering member 6.

[0061] like Figure 2 As shown, functional area 101 is located in welding area 102. Welding area 102 is provided with annular welding component 6. The encapsulation layer 5 of surface acoustic wave filter 100 in this embodiment of the invention is connected to the front side of filter chip 1 by welding component 6, thereby making the connection between encapsulation layer 5 and filter chip 1 convenient.

[0062] Optionally, the encapsulation layer 5 has a relief groove 501 with an opening facing the filter chip 1, and a cavity is formed between the relief groove 501 and the front side of the filter chip 1.

[0063] like Figure 4As shown, the opening of the clearance groove 501 on the encapsulation layer 5 is set downward, and a cavity is formed between the clearance groove 501 and the front side of the filter chip 1. By setting the clearance groove 501 on the encapsulation layer 5, a cavity structure is formed between the clearance groove 501 and the front side of the filter chip 1, so as to avoid the encapsulation layer 5 contacting the metal pattern 2 of the functional area and affecting the performance of the surface acoustic wave filter 100. Thus, the surface acoustic wave filter 100 of the present invention has a simple structure and is easy to assemble.

[0064] Optionally, weldment 6 is a ring-shaped welded piece.

[0065] The surface acoustic wave filter 100 of this embodiment of the invention has a smaller thickness by setting the welding part 6 as a welding piece and welding it to the encapsulation layer 5, which is beneficial to further reduce the thickness of the surface acoustic wave filter 100 of this embodiment of the invention.

[0066] The packaging method of the surface acoustic wave filter 100 according to an embodiment of the present invention includes the following steps:

[0067] Step 1: Fabricate a first through-hole 103, a second through-hole 104, and a third through-hole 105 extending along the thickness direction on the wafer, and provide a first conductive element 401 in the first through-hole 103, a second conductive element 402 in the second through-hole 104, and a third conductive element in the third through-hole 105.

[0068] Step 2: Fabricate an input electrode 201, an output electrode 202, and a ground electrode 203 on the first surface of the wafer, and electrically connect the input electrode 201, the output electrode 202, and the ground electrode 203 to the first conductive element 401, the second conductive element 402, and the third conductive element, respectively.

[0069] Step 3: Fabricate input pin 301, output pin 302 and ground pin on the second surface of the wafer, and electrically connect input pin 301, output pin 302 and ground pin to the first conductive element 401, the second conductive element 402 and the third conductive element respectively;

[0070] Step 4: The wafer is cut to form filter chip 1. The surface of filter chip 1 corresponding to the first surface forms the front side of filter chip 1, and the surface of filter chip 1 corresponding to the second surface forms the back side of filter chip 1.

[0071] Step 5: Fix the encapsulation layer 5 to the front of the filter chip 1.

[0072] The process route of the surface acoustic wave (SAW) filter 100 packaging method of this invention includes: fabricating through-holes on a wafer, filling the through-holes with metal material, fabricating metal patterns 2, wafer dicing, and sealing. Those skilled in the art will understand that the process route of related SAW filter packaging methods involves: fabricating metal patterns on a wafer, processing a packaging substrate, pad ball placement, wafer dicing, chip flip bonding, and molding sealing. The processing of the packaging substrate and other processes are generally performed in different factories, requiring transfer manufacturing. The SAW filter 100 packaging method of this invention eliminates the packaging substrate structure, thus eliminating the processing steps of the packaging substrate, pad ball placement, and chip flip bonding. This not only significantly shortens the manufacturing process of the SAW filter 100 of this invention but also saves materials and reduces manufacturing costs.

[0073] Therefore, the packaging method of the surface acoustic wave filter 100 in this embodiment of the invention has the advantages of simple process and low manufacturing cost.

[0074] Optionally, in step one, existing laser etching or chemical etching techniques can be used to fabricate the first through-hole 103, the second through-hole 104, and the third through-hole 105 on the wafer. Electroplating is then used to fill the first through-hole 103, the second through-hole 104, and the third through-hole 105 with metal material, typically copper, silver, or an alloy. Metal pillars are formed within these three through-holes. The metal pillar in the first through-hole 103 forms the first conductive element 401, the metal pillar in the second through-hole 104 forms the second conductive element 402, and the metal pillar in the third through-hole 105 forms the third conductive element.

[0075] Optionally, in step two, the existing manufacturing process of the filter chip 1 can be used, namely, spin coating of photoresist, photolithography and development of a mask, metal film deposition, stripping, cleaning and other processes to create a metal pattern 2, and connecting the input electrode 201 on the metal pattern 2 to the first conductive element 401, the output electrode 202 to the second conductive element 402, and the ground electrode 203 to the third conductive element.

[0076] Optionally, in step three, the pins can be fabricated using the same process as in step two for fabricating the metal pattern 2. That is, input pin 301, output pin 302, and ground pin are fabricated on the second surface of the wafer using processes such as spin-coating photoresist, photolithography and development, metal film deposition, stripping, and cleaning.

[0077] Optionally, the encapsulation layer 5 is soldered and fixed to the filter chip 1.

[0078] For example, the same process as manufacturing the metal pattern 2 in step two is used on the front side of the filter chip 1. That is, a ring-shaped solder pad is formed in the soldering area 102 of the filter chip 1 by spin coating photoresist, photolithography and development of mask, metal film deposition, peeling, and cleaning. Both the solder pad and the encapsulation layer 5 are made of metal. By welding the solder pad and the encapsulation layer 5, the encapsulation layer 5 is sealed and mounted on the front side of the filter chip 1, forming a cavity between the encapsulation layer 5 and the filter chip 1.

[0079] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0080] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0081] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0082] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0083] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0084] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A surface acoustic wave filter, characterized in that, include: A filter chip has a functional area on its front side, which includes an input electrode, an output electrode, and a ground electrode. The back side of the filter chip has an input pin, an output pin, and a ground pin. A first through-hole, a second through-hole, and a third through-hole extending along the thickness direction are provided on a wafer. A first conductive element is disposed in the first through-hole, a second conductive element is disposed in the second through-hole, and a third conductive element is disposed in the third through-hole. The wafer is diced to form the filter chip. The input pin is electrically connected to the input electrode through the first conductive element, the output pin is electrically connected to the output electrode through the second conductive element, and the ground pin is electrically connected to the ground electrode through the third conductive element. as well as An encapsulation layer is disposed on the front side of the filter chip, a cavity is formed between the encapsulation layer and the filter chip, and the functional area is disposed within the cavity; The filter chip has a first groove on its back side, and the first through hole communicates with the first groove. A portion of the input pin is located inside the first groove, and another portion of the input pin is located outside the first groove; and / or The filter chip has a second groove on its back side, which communicates with the second through hole. A portion of the output pin is located inside the second groove, and the other portion of the output pin is located outside the second groove; and / or The filter chip has a third groove on its back side, which is connected to the third through hole. A portion of the grounding pin is located inside the third groove, and the other portion of the grounding pin is located outside the third groove.

2. The surface acoustic wave filter according to claim 1, characterized in that, The first groove is disposed in the thickness direction of the filter chip corresponding to the first through hole, the second groove is disposed in the thickness direction of the filter chip corresponding to the second through hole, and the third groove is disposed in the thickness direction of the filter chip corresponding to the third through hole.

3. The surface acoustic wave filter according to claim 1, characterized in that, The front side of the filter chip also has a soldering area, which surrounds the functional area. The surface acoustic wave filter also includes an annular solder joint, which is disposed within the soldering area. The encapsulation layer and the filter chip are soldered together through the solder joint.

4. The surface acoustic wave filter according to claim 3, characterized in that, The welded component is a welded sheet.

5. The surface acoustic wave filter according to any one of claims 1-4, characterized in that, The functional area is provided with a metal pattern, which has the input electrode, the output electrode and the ground electrode. The metal pattern includes multiple resonators, each of which is provided with an interdigital transducer. The multiple resonators are connected in series and / or in parallel.

6. The surface acoustic wave filter according to claim 5, characterized in that, At least one of the resonators has the ground electrode.

7. The surface acoustic wave filter according to any one of claims 1-4, characterized in that, The encapsulation layer has a clearance groove with an opening facing the filter chip, and the cavity is formed between the clearance groove and the front side of the filter chip.

8. A packaging method for a surface acoustic wave filter, characterized in that, The surface acoustic wave filter is the surface acoustic wave filter according to any one of claims 1-7, comprising the following steps: A first through-hole, a second through-hole, and a third through-hole extending along the thickness direction are formed on the wafer, and a first conductive element is disposed in the first through-hole, a second conductive element is disposed in the second through-hole, and a third conductive element is disposed in the third through-hole. An input electrode, an output electrode, and a ground electrode are fabricated on the first surface of the wafer, and the input electrode, the output electrode, and the ground electrode are electrically connected to the first conductive element, the second conductive element, and the third conductive element, respectively. An input pin, an output pin, and a ground pin are fabricated on the second surface of the wafer, and the input pin, the output pin, and the ground pin are electrically connected to the first conductive element, the second conductive element, and the third conductive element, respectively. The wafer is cut to form a filter chip, the surface of the filter chip corresponding to the first surface forms the front side of the filter chip, and the surface of the filter chip corresponding to the second surface forms the back side of the filter chip. The encapsulation layer is fixed to the front side of the filter chip.

9. The packaging method for a surface acoustic wave filter according to claim 8, characterized in that, The encapsulation layer is welded and fixed to the filter chip.

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