Packaging structure

Abstract

According to the packaging structure provided by the utility model, the plastic packaging layer or the plastic packaging layer and the isolation layer are formed by combining different plastic packaging processes according to different material flowability of the plastic packaging layer, then the thickness of the packaging structure is reduced through a whole grinding process, and then splitting is carried out before or after the thickness of the packaging structure is reduced. Therefore, under the condition that a traditional splitting mode of the filter chip does not need to be changed, it can be guaranteed that the thickness of the packaging structure reaches the target precision, the problem that the wafer warps too much is avoided, and meanwhile the purpose that the cavity is prevented from being invaded by the material of the plastic packaging layer is achieved. Moreover, the sound absorption layer is arranged on the back surface of the thinned filter chip in the packaging structure, so that the problem that the performance of the filter fails due to body wave reflection on the back surface of the filter chip caused by gradual thinning of the thickness of the packaging structure of the existing filter chip can be avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of communications, in particular to a packaging structure. Background Art

[0002] Filters can be categorized into various types based on their implementation, such as LC filters, cavity filters, acoustic filters, and dielectric filters. In the mobile communications sector, small, high-performance acoustic filters are required due to the generally small size and low power consumption of portable electronic devices. Currently, the mainstream packaging process in China is CSP (Chip Scale Package), which involves flip-chip and resin encapsulation of a piezoelectric chip, substrate, metal balls, and a resin encapsulation film to achieve CSP packaging. This allows for the transmission of electrical and mechanical signals and the packaging and protection of the device.

[0003] Surface Acoustic Wave Filter (SAWFilter) is one of the core components in the field of radio frequency communication. It uses sound waves to transmit on the front of the chip to achieve its function. Therefore, the packaging of the SAW filter chip must ensure that the surface of the interdigital transducer (the working sensor of the SAW filter) on the front of the chip cannot contact other substances, that is, it is necessary to ensure that there is enough cavity on the front of the chip, otherwise it will affect signal transmission.

[0004] Currently, the typical thickness of a conventional CSP filter multiplexer is 0.5mm. Further thinning to 0.35mm requires thinning the filter chip to less than 0.15mm. At this point, the traditional post-thinning cutting process (DAG) cannot meet this requirement due to issues such as excessive warping after thinning. Therefore, a pre-thinning half-cut process (DBG) is required during substrate splitting to achieve a thinner filter chip thickness. Furthermore, as the filter chip thickness decreases, the impact of bulk waves reflected from the back of the filter chip on SAW filter performance becomes increasingly difficult to ignore. Utility Model Content

[0005] The purpose of the utility model is to provide a packaging structure to solve the problems of the existing filter chip packaging structure, such as the body wave reflection on the back of the filter chip resulting from the gradual thinning of the thickness, which leads to the failure of the filter performance, and the excessive warping of the wafer during wafer splitting.

[0006] In a first aspect, in order to solve the above technical problems, the present invention provides a packaging structure, which may at least include: a substrate;

[0007] at least one filter chip, disposed on the substrate, with the front surface of the filter chip facing the substrate and a gap between the filter chip and the substrate;

[0008] The plastic packaging layer covers the side walls of the filter chip and the substrate surfaces on both sides of the filter chip to enclose the gap, so that a sealed cavity is formed between the filter chip and the substrate.

[0009] In some examples, the packaging structure may further include:

[0010] The sound absorbing layer spans over the filter chip and the plastic packaging layer to cover the back surface of the filter chip and the top surface of the plastic packaging layer.

[0011] In some examples, the packaging structure may further include:

[0012] The isolation layer includes a continuous first portion and a second portion, wherein the first portion is located between the plastic packaging layer, the filter chip and the cavity, and the second portion is located between the plastic packaging layer and the substrate thereunder.

[0013] In some examples, the isolation layer may further include: a second portion located between the molding layer and the substrate thereunder, wherein the first portion and the second portion are in direct contact with each other.

[0014] In some examples, a top surface of the molding layer and a top surface of the first portion of the isolation layer may be located at the same level.

[0015] In some examples, in the vertical direction, the height of the first portion of the isolation layer may be equal to the sum of the heights of the second portion thereof and the molding layer.

[0016] In some examples, the packaging structure may further include:

[0017] A plurality of bumps are located between the filter chip and the substrate.

[0018] In some examples, the material of the molding layer may be a thermosetting or thermoplastic molding compound containing inorganic fillers, and the inorganic filler may be one or a combination of aluminum oxide, titanium oxide, silicon nitride, aluminum nitride, and silicon dioxide.

[0019] In some examples, the material of the sound absorbing layer may be an organic material containing a sound absorbing filler, or may be an inorganic material or a metal material having sound absorbing properties. The sound absorbing filler may be a material having a relatively high acoustic impedance.

[0020] In some examples, the thickness of the packaging structure may range from 0.20 mm to 0.35 mm.

[0021] In some examples, the filter chip may be an acoustic wave filter chip, or a solid-state assembled bulk wave filter chip.

[0022] In a second aspect, based on the same utility model concept, the present utility model further provides a packaging method for a packaging structure, which may include at least the following steps:

[0023] providing a substrate;

[0024] Disposing at least one filter chip on the substrate, with the front surface of the filter chip facing the substrate and a gap between the filter chip and the substrate;

[0025] forming a molding material layer, wherein the molding material layer covers the sidewalls and top surface of the filter chip and extends to cover the substrate surface on both sides of the filter chip to encapsulate the gap, so that a sealed cavity is formed between the filter chip and the substrate;

[0026] The plastic encapsulation material layer and part of the height of the filter chip are removed to expose the back of the remaining portion of the filter chip, and a plastic encapsulation layer is formed that only covers the side walls of the remaining portion of the filter chip and the substrate surfaces on both sides of the filter chip.

[0027] In some examples, before forming the molding material layer, the packaging method of the packaging structure may further include: forming an isolation layer on the sidewalls and top surface of the filter chip and on the substrate surfaces on both sides of the filter chip.

[0028] In some examples, the material of the molding material layer may be a thermosetting molding material containing inorganic fillers; and the process of forming the molding material layer may include a C-mold process.

[0029] In some examples, the material of the molding material layer may be a thermoplastic molding material containing inorganic fillers; and the process of forming the molding material layer may include vacuum lamination.

[0030] In some examples, the process of removing the molding material layer may include a grinding process, and in the process of removing a portion of the molding material layer, a portion of the isolation layer may also be removed simultaneously.

[0031] In some examples, after forming the plastic packaging layer, the method may further include forming a sound absorbing layer, wherein the sound absorbing layer covers the back surface of the filter chip and the top surface of the plastic packaging layer.

[0032] In some examples, before or after forming the sound absorbing layer, the process may further include: cutting the plastic encapsulation layer and the substrate along the edges of the regions on both sides of the plastic encapsulation layer to obtain a packaging structure of at least one single filter chip, wherein in the packaging structure of each single filter chip, the edge of the plastic encapsulation layer is flush with the edges of the sound absorbing layer and the isolation layer.

[0033] In some examples, the process of forming the sound absorbing layer may include vacuum lamination or vacuum deposition.

[0034] In some examples, the filter chip may be a surface acoustic wave filter chip, or a solid-state assembled bulk wave filter chip.

[0035] Compared to the prior art, the filter packaging structure provided by the present invention includes a substrate, at least one filter chip, a plastic encapsulation layer, and a sound-absorbing layer. The filter chip is disposed on the substrate, with the front surface of the filter chip facing the substrate and a gap between the filter chip and the substrate. The plastic encapsulation layer covers the sidewalls of the filter chip and the substrate surface on both sides of the filter chip to enclose the gap, thereby forming a sealed cavity between the filter chip and the substrate. The sound-absorbing layer spans the filter chip and the plastic encapsulation layer, covering the back surface of the filter chip and the top surface of the plastic encapsulation layer.

[0036] Because the present invention, based on the different material fluidity of the molding layer, forms an isolation layer to separate the molding layer from the cavity below the filter chip before forming the molding layer of the thermosetting molding compound containing inorganic fillers using the C-mold process, or directly forms the molding layer of the thermoplastic molding compound containing inorganic fillers using vacuum lamination (without forming the isolation layer), and then thins the thickness of the packaging structure through a full grinding process before or before performing the splitting process. This ensures that the thickness of the packaging structure reaches the target accuracy without changing the traditional splitting method of the filter chip, and prevents the problem of excessive wafer warpage. At the same time, it also avoids the purpose of the molding layer material invading the cavity. In addition, because the back of the thinned filter chip in the packaging structure of the present invention is provided with a sound-absorbing layer, it can also avoid the problem of bulk wave reflection on the back of the filter chip resulting from the gradual thinning of the thickness of the existing filter chip packaging structure, which leads to filter performance failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The accompanying drawings are used to provide a further understanding of the present application and constitute a part of the specification. Together with the following detailed description, they are used to explain the present application but do not constitute a limitation of the present application. In the accompanying drawings:

[0038] Figure 1 Schematic diagram of the cross-section of the existing packaging structure.

[0039] Figure 2 This is a cross-sectional schematic diagram of an example of a packaging structure in an embodiment of the present invention.

[0040] Figure 3 It is a cross-sectional schematic diagram of another example of the packaging structure in one embodiment of the present utility model.

[0041] Figure 4 In one embodiment of the present utility model, Figure 3 A cross-sectional schematic diagram of an evolution example of the packaging structure.

[0042] Figure 5 The figure is a flow chart of a packaging method of a packaging structure according to an embodiment of the present invention.

[0043] Figures 6 to 11 This utility model is directed to an embodiment of Figure 2 The structural schematic diagram corresponding to the corresponding steps of the packaging method of the packaging structure shown.

[0044] Figures 12 to 18 This utility model is directed to an embodiment of Figure 3 The structural schematic diagram corresponding to the corresponding steps of the packaging method of the packaging structure shown.

[0045] The description of the accompanying drawings is as follows:

[0046] 100 / 1 - substrate; 200a - filter chip before grinding; 200 / 3 - filter chip; 201 / 5 - cavity; 202 - bump; 300 - isolation layer; 300a - first part of isolation layer; 300b - second part of isolation layer; 401 - molding material layer; 400 - molding layer; 500 - sound absorption layer; 2 - metal bump structure; 4 - molding body.

[0047] In the drawings, like components are given like reference numerals, and the drawings are not drawn to scale. DETAILED DESCRIPTION

[0048] The packaging structure proposed by the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are highly simplified and not to exact scale, and are intended solely to facilitate and clearly illustrate the embodiments of the present invention.

[0049] Please refer to Figure 1 , Figure 1 It is a cross-sectional schematic diagram of the existing packaging structure. Figure 1 1 is the substrate, 2 is the metal bump structure, 3 is the filter chip, and 4 is the plastic package. Figure 1 As shown in the figure, the thickness of the packaging structure of the existing CSP filter such as the SAW filter is relatively thick, and the plastic package 4 will flow laterally into the part of the cavity 5 below the filter chip 3 due to the high fluidity of the material (such as Figure 1 The black dotted line framed area) causes the filter chip 3 to fail.

[0050] In order to solve the above-mentioned problems existing in the prior art, an embodiment of the present invention provides a packaging structure. The core idea of ​​the present invention is: according to the different material fluidity of the plastic sealing layer, a plastic sealing layer or a plastic sealing layer and an isolation layer are formed in combination with different plastic sealing processes, and a sound-absorbing layer is set on the back of the thinned filter chip in the packaging structure, thereby solving the problems of the existing filter chip packaging structure resulting in body wave reflection on the back of the filter chip causing filter performance failure as the thickness gradually decreases, and excessive warping of the wafer when it is split.

[0051] Example 1

[0052] Please refer to Figure 2 , Figure 2 FIG. 1 is a cross-sectional diagram of an example of a packaging structure in an embodiment of the present invention. Figure 2 As shown, the packaging structure includes:

[0053] substrate 100;

[0054] A filter chip 200 is disposed on the substrate 100 , with the front of the filter chip 200 facing the substrate 100 and a gap between the filter chip 200 and the substrate 100 ;

[0055] a plastic encapsulation layer 400 covering the sidewalls of the filter chip 200 and the surface of the substrate 100 on both sides of the filter chip 200 to enclose the gap, so that a sealed cavity 201 is formed between the filter chip 200 and the substrate 100;

[0056] The sound absorbing layer 500 spans over the filter chip 200 and the plastic packaging layer 400 to cover the back surface of the filter chip 200 and the top surface of the plastic packaging layer 400 .

[0057] Specifically, the substrate 100 may include, but is not limited to, a piezoelectric layer (not shown), an IDT (interdigital transducer) (not shown), a substrate (not shown), a trap layer (not shown), and one or more dielectric layers (not shown). The substrate may be made of, for example, lithium tantalate (LT), lithium niobate (LN), or POI; the trap layer may be made of, for example, polysilicon; and the dielectric layer may be made of, for example, silicon dioxide, silicon nitride, etc., but is not limited to these. The filter chip 200 may be an acoustic wave filter chip, or a solid-state assembled bulk wave filter chip, comprising opposing front and back sides and sidewalls connecting the front and back sides. The front side of the filter chip 200 is provided with an interdigital transducer and other functional components. The front side of the filter chip 200 faces the substrate 100 and is provided with a plurality of bumps 202, which may be solder balls or metal pillars. The bumps 202 may be electrically connected to corresponding pads on the substrate 100 by flip-chip die bonding (FCDie Bond), thereby securing the filter chip 200 to the substrate 100. Because the bumps 202 have a certain height, a gap is created between the front side of the filter chip 200 and the substrate 100.

[0058] In this embodiment, the material of the plastic encapsulation layer 400 is a thermoplastic encapsulation compound containing inorganic fillers. The inorganic fillers may specifically be one or a combination of aluminum oxide, titanium oxide, silicon nitride, aluminum nitride, and silicon dioxide. The purpose is to enhance the hardness of the thermoplastic encapsulation compound, improve processing performance, and reduce costs, but the present invention is not limited thereto. Because the thermoplastic encapsulation compound containing inorganic fillers has the characteristics of strong plasticity and high hardness, the plastic encapsulation layer 400 in this embodiment does not intrude into the gap between the filter chip 200 and the substrate 100 during the encapsulation process. Consequently, a sealed cavity 201 is formed between the filter chip 200 and the substrate 100, thereby ensuring the performance of the filter chip 200.

[0059] Furthermore, the material of the sound absorbing layer 500 is an organic material containing a sound absorbing filler, or an inorganic material or a metal material having sound absorbing properties. The sound absorbing filler may specifically be a material having a high acoustic impedance, but is not limited thereto. In this embodiment, the thickness of the packaging structure including the sound absorbing layer 500 is within the range of 0.20 mm to 0.35 mm, specifically 0.20 mm, 0.21 mm, 0.22 mm, 0.25 mm, 0.26 mm, 0.28 mm, 0.29 mm, 0.30 mm, 0.31 mm, 0.32 mm, 0.33 mm, 0.34 mm, or 0.35 mm. That is, the thickness accuracy of the packaging structure in this embodiment can be controlled to 0.35 mm or even less. Therefore, to avoid bulk wave reflection on the back of the filter chip 200 due to the thin thickness of the packaging structure, which may cause filter performance failure, the sound absorbing layer 500 is further provided on the back of the filter chip 200 in this embodiment. This ensures that the performance of the filter chip 200 is not failed while achieving the purpose of reducing the thickness of the packaging structure.

[0060] A person skilled in the art of the present invention should readily understand that, in order to meet the actual product requirements, the packaging structure of the present invention may also have other aspects and is not limited to the above. The following will further describe other embodiments or variations of the packaging structure of the present invention. To simplify the description, the following description will focus on the differences between the various embodiments and will not repeat the similarities. Furthermore, the same components in the various embodiments of the present invention are designated with the same reference numerals to facilitate comparison between the various embodiments.

[0061] Example 2

[0062] Please refer to Figure 3 and Figure 4 , Figure 3 FIG. 1 is a cross-sectional diagram of another example of a packaging structure in an embodiment of the present invention. Figure 4 In one embodiment of the present utility model, Figure 3 A cross-sectional diagram of an evolution example of the packaging structure is shown. Figure 3 and Figure 4 As shown, the structure of the package structure of this embodiment is substantially the same as that of the package structure in the first embodiment. For example, the package structure also includes a substrate 100, a filter chip 200, a cavity 201, a plurality of bumps 202, a plastic layer 400 and a sound absorbing layer 500. The same parts are not repeated here. The main difference between the package structure of this embodiment and the first embodiment is that the package structure is further provided with an isolation layer 300, wherein the isolation layer 300 can include a continuous first portion 300a and a second portion 300b, as shown in FIG. Figure 3In detail, the first portion 300a of the isolation layer 300 is specifically located between the plastic encapsulation layer 400, the filter chip 200, and the cavity 201, and the second portion 300b of the isolation layer 300 is located between the plastic encapsulation layer 400 and the substrate 100 thereunder, and the first portion 300a and the second portion 300b of the isolation layer 300 are in direct contact (i.e., the two are an integrally formed continuous structure) to form an L-shaped structure; in this setting, the top surface of the plastic encapsulation layer 400 is in contact with the substrate 100. The top surfaces of the first portions 300a of the isolation layer 300 are located at the same horizontal height, and in a direction perpendicular to the surface of the substrate 100 (hereinafter referred to as the vertical direction), the height of the first portion 300a of the isolation layer 300 is equal to the sum of the heights of the second portion 300b thereof and the plastic encapsulation layer 400. This allows the sound absorbing layer 500 to span over the plastic encapsulation layer 400, the isolation layer 300, and the filter chip 200 in a direction parallel to the surface of the substrate 100 (hereinafter referred to as the horizontal direction).

[0063] In this embodiment, the material of the plastic encapsulation layer 400 is a thermosetting plastic encapsulation material containing inorganic fillers. The inorganic fillers may also be one or more combinations of aluminum oxide, titanium oxide, silicon nitride, aluminum nitride, and silicon dioxide. The purpose is to enhance the hardness of the thermoplastic plastic encapsulation material, improve processing performance, and reduce costs, but the present invention is not limited thereto. Since the thermosetting plastic encapsulation material has high fluidity, in order to prevent the plastic encapsulation layer 400 from invading the gap between the filter chip 200 and the substrate 100 during the molding process (i.e., injection molding isolation), this embodiment not only includes inorganic fillers such as silicon dioxide in the thermoplastic plastic encapsulation material that can enhance the hardness and reduce its fluidity, but also further provides a first portion 300a of the isolation layer 300 with an isolation function between the plastic encapsulation layer 400 and the filter chip 200 and the cavity 201 thereunder to ensure that the performance of the filter chip 200 is not damaged. Furthermore, the packaging structure in this embodiment is also provided with a sound-absorbing layer 500 made of an organic material containing a sound-absorbing filler, or an inorganic material or a metal material having sound-absorbing properties. Therefore, this embodiment can also achieve the purpose of avoiding the problem of body wave reflection on the back side of the filter chip 200 due to the thin thickness of the packaging structure, thereby causing the filter performance failure problem.

[0064] It should be understood that since the isolation layer 300 in this embodiment is mainly used to isolate the plastic sealing layer 400 from invading the gap between the filter chip 200 and the substrate 100 during the plastic sealing process (i.e., injection molding isolation), it is sufficient to provide only the first portion 300a of the isolation layer 300 to achieve this purpose. Figure 3 Can be further simplified as Figure 4 The corresponding structure, but not limited to this.

[0065] Based on this, the embodiment of the present invention further provides a packaging method for a packaging structure. Figure 5 Flowchart of the packaging method of the packaging structure provided by the embodiment of the present utility model. Figure 5 As shown, the packaging method of the packaging structure includes:

[0066] Step S501, providing a substrate;

[0067] Step S502, placing at least one filter chip on the substrate, with the front surface of the filter chip facing the substrate and a gap between the filter chip and the substrate;

[0068] Step S503: forming a molding material layer, wherein the molding material layer covers the sidewalls and top surface of the filter chip and extends to cover the substrate surface on both sides of the filter chip to encapsulate the gap, so that a sealed cavity is formed between the filter chip and the substrate;

[0069] Step S504 , removing a portion of the height of the plastic encapsulation material layer to expose the back surface of the filter chip, and forming a plastic encapsulation layer that only covers the sidewalls of the filter chip and the substrate surface on both sides of the filter chip.

[0070] In order to enable general technicians in the technical field to which the present invention belongs to easily understand the packaging method of the packaging structure in the embodiment of the present invention, the packaging method of the packaging structure proposed in the present invention will be further explained below in combination with the structural schematic diagram corresponding to the corresponding steps of the packaging method.

[0071] It should be noted that a person skilled in the art of the present invention should be able to easily understand that the substrate 100 or the wafer can simultaneously include one or more filter chips 200. In order to simplify the drawing, in the drawings provided in the following embodiments of the present invention, only two filter chips 200 are provided on the substrate. In other embodiments, it may also include one or three or more filter chips 200, and their respective corresponding packaging structures and manufacturing methods are the same as those provided in the drawings provided in the present invention. Figure 1 To.

[0072] Example 3

[0073] Figures 6 to 11 , Figures 6 to 11 This embodiment provides Figure 2 A structural schematic diagram corresponding to the corresponding steps of the packaging method of the packaging structure.

[0074] Execute step S501: Please refer to Figure 6A substrate 100 is provided. The substrate 100 includes a circuit structure, such as a piezoelectric layer (not shown), an IDT (interdigital transducer) (not shown), a substrate (not shown), a trap layer (not shown), and one or more dielectric layers (not shown), but is not limited thereto. The substrate can be made of, for example, LT (lithium tantalate), LN (lithium niobate), or POI. Furthermore, the substrate 100 includes a plurality of pads (not shown) electrically connected to the circuit structure. The substrate 100 can be a wafer.

[0075] Execute step S502: Continue to refer to Figure 6 , providing at least one filter chip 200a ( Figure 6 Only two filter chips 200a are shown in the figure. The front of the filter chip 200a has a plurality of bumps 202. The bumps 202 on the front of the filter chip 200a are electrically connected to the corresponding pads on the substrate 100 by flip-chip bonding or other methods, thereby setting the filter chip 200 on the substrate 100. The front of the filter chip 200a faces the substrate 100, and there is the gap between the filter chip 200a and the substrate 100. It should be understood that since the filter chip 200 in the embodiment of the present invention is prepared through a grinding process, in order to facilitate distinction, the filter chip before grinding in the embodiment of the present invention is identified with the reference numeral 200a. In one embodiment, the filter chip 200a before grinding and its corresponding filter chip 200 may be an acoustic wave filter chip, or a solid-state assembled bulk wave filter chip.

[0076] Execute step S503: Please refer to Figure 7 A vacuum lamination process is used to coat the sidewalls and top surface of each filter chip 200a, as well as the surface of the substrate 100 on both sides of the filter chip 200a, with a thermoplastic molding compound containing an inorganic filler, to form a molding material layer 401. Because the thermoplastic molding compound containing an inorganic filler in this embodiment has strong plasticity and hardness, the molding layer 400 in this embodiment does not intrude into the gap between the filter chip 200a and the substrate 100 during the molding process. Consequently, a sealed cavity 201 is formed between the filter chip 200a and the substrate 100, thereby ensuring the performance of the filter chip 200a.

[0077] Execute step S504: Please refer to Figure 8The plastic encapsulation material layer 401 and part of the height of the filter chip 200a can be removed in the vertical direction to the desired thickness by using a thinning process such as grinding to obtain a thinned filter chip 200 and expose the back of the filter chip 200. The remaining plastic encapsulation material layer 401 that only covers the side walls of the filter chip 200 and the surface of the substrate 100 on both sides of the filter chip 200 after thinning is used as the plastic encapsulation layer 400.

[0078] It should be understood that the packaging method of the packaging structure provided in the embodiment of the present invention further includes:

[0079] In step S505, a sound-absorbing layer 500 is formed, covering the back surface of the filter chip 200 and the top surface of the plastic encapsulation layer 400. In this configuration, following step S504, the sound-absorbing layer 500 can be formed first, followed by cutting adjacent filter chips 200 and their corresponding film layers to obtain a package structure of multiple single filter chips (as shown in Example 1 below). Alternatively, the edges of the adjacent filter chips 200 and their corresponding film layers can be cut first, and then the sound-absorbing layer 500 can be formed on the top surface of each cut filter chip 200 and the plastic encapsulation layer 400 (as shown in Example 2 below). In one embodiment, the sound-absorbing layer 500 is made of an organic material containing a sound-absorbing filler, or an inorganic or metallic material with sound-absorbing properties. The sound-absorbing filler can be, but is not limited to, a material with high acoustic impedance.

[0080] Example 1, execute step S505: Please refer to Figure 9 and Figure 11 , and combined with Figure 2 , using a vacuum lamination process or a vacuum coating process (such as magnetron sputtering), the sound absorbing layer 500 is formed on the back surface of the filter chip 200 and the top surface of the plastic layer 400, and then the plastic layer 400 and the substrate 100 are cut vertically downward along the mid-perpendicular line between adjacent filter chips 200 to obtain a packaging structure of at least one single filter chip (such as Figure 2 As shown), in the packaging structure of each single filter chip, the edge of the plastic packaging layer 400 is flush with the edge of the sound absorbing layer 500.

[0081] Example 2, please refer to Figure 10 and Figure 11 , and combined with Figure 2 The plastic encapsulation layer 400 and the substrate 100 can be cut vertically downward along the mid-perpendicular line of the plastic encapsulation layer 400 between the adjacent filter chips 200 to obtain Figure 10The plurality of discrete structures shown in FIG5 are then subjected to step S505: using a vacuum lamination process or a vacuum coating process (such as magnetron sputtering), the sound absorbing layer 500 is formed on the back surface of the filter chip 200 and the top surface of the plastic layer 400 in each of the discrete structures, so as to obtain a packaging structure of at least one single filter chip (such as FIG5 ). Figure 2 As shown), in the packaging structure of each single filter chip, the edge of the plastic packaging layer 400 is flush with the edge of the sound absorbing layer 500.

[0082] It should be understood that if Figure 7 The height of the substrate 100 and the corresponding structure formed with the molding material layer 401 in the vertical direction is defined as a first height H1. Figure 8 The height of the substrate 100 and the corresponding structure formed with the plastic encapsulation layer 400 after thinning is defined as a second height H2 in the vertical direction. Therefore, H1>H2>0, and the value range of H2 is 0.20mm-0.35mm. That is, the thickness of the package structure of a single filter chip including the sound absorbing layer 500 in this embodiment is in the range of 0.20mm-0.35mm. In other words, the thickness accuracy of the package structure in this embodiment can be controlled to 0.35mm or even less.

[0083] Example 4

[0084] Figures 12 to 18 , Figures 12 to 18 This embodiment provides Figure 3 The packaging method of the packaging structure in this embodiment is roughly the same as the packaging method in the aforementioned embodiment 3. For example, Figure 12 As shown, step S501 is performed: providing the substrate 100, and then step S502 is performed: providing at least one filter chip 200a ( Figure 12 Only two filter chips 200a are shown in the figure. The front of the filter chip 200a faces the substrate 100 and there is the gap between the filter chip 200a and the substrate 100. The same details are not repeated here.

[0085] The main differences between the packaging structure of this embodiment and the aforementioned third embodiment are:

[0086] Please refer to Figure 13 An isolation layer 300 is formed on the sidewalls and top surface of the filter chip 200 a and on the surface of the substrate 100 on both sides of the filter chip 200 a . The isolation layer 300 may be an organic thin film.

[0087] Please refer to Figure 14, executing step S503: using a C-mold process to form a molding material layer 401 wrapped around the surface of the isolation layer 300. At this time, the material of the molding material layer 401 is a thermosetting molding compound containing inorganic fillers, such as epoxy molding compound (EMC). The inorganic filler can also be one or a combination of aluminum oxide, titanium oxide, silicon nitride, aluminum nitride and silicon dioxide. The purpose is to enhance the hardness of the thermoplastic molding compound, improve processing performance and reduce costs, but is not limited to this.

[0088] Please refer to Figure 15 , executing step S504: using a thinning process such as grinding, vertically remove portions of the molding material layer 401, the isolation layer 300, and the filter chip 200a to a desired thickness, thereby obtaining a thinned filter chip 200 and exposing the back surface of the filter chip 200. The remaining molding material layer 401 remaining after thinning, which only covers the surface of the isolation layer 300, serves as the molding layer 400. Subsequently, the sound absorption layer 500 can be formed first, and then adjacent filter chips 200 and their corresponding film layers can be cut to obtain a package structure of multiple single filter chips (as shown in Example 3 below). Alternatively, the edges of the adjacent filter chips 200 and their corresponding film layers can be cut first, and then the sound absorption layer 500 can be formed on the top surface of each cut filter chip 200 and the molding layer 400 (as shown in Example 4 below).

[0089] Example 3, please refer to Figure 16 and Figure 18 , and combined with Figure 3 , executing step S505: using a vacuum lamination process or a vacuum coating process (such as magnetron sputtering), forming the sound absorbing layer 500 on the back surface of the filter chip 200, the isolation layer 300 and the top surface of the plastic layer 400, and then vertically cutting the plastic layer 400, the isolation layer 300 and the substrate 100 along the mid-perpendicular line of the plastic layer 400 between adjacent filter chips 200 to obtain a packaging structure of at least one single filter chip (such as Figure 3 As shown), in the packaging structure of each single filter chip, the edges of the plastic packaging layer 400 and the isolation layer 300 are flush with the edge of the sound absorbing layer 500.

[0090] Example 4, please refer to Figure 17 and Figure 18 , and combined with Figure 3 The plastic encapsulation layer 400, the isolation layer 300 and the substrate 100 can be cut vertically downward along the mid-perpendicular line of the plastic encapsulation layer 400 between the adjacent filter chips 200 to obtain Figure 17The plurality of discrete structures shown in FIG5 are then subjected to step S505: a vacuum lamination process or a vacuum coating process (such as magnetron sputtering) is used to form the sound absorbing layer 500 on the back surface of the filter chip 200, the isolation layer 300, and the top surface of the plastic layer 400 in each of the discrete structures, so as to obtain a packaging structure of at least one single filter chip (such as FIG5 ). Figure 3 As shown), in the packaging structure of each single filter chip, the edge of the plastic packaging layer 400 is flush with the edge of the sound absorbing layer 500.

[0091] Similarly, if Figure 14 The height of the substrate 100 and the corresponding structure formed with the molding material layer 401 in the vertical direction is defined as a first height H1. Figure 15 The height of the substrate 100 and the corresponding structure formed with the plastic encapsulation layer 400 after thinning is defined as a second height H2 in the vertical direction. Therefore, H1>H2>0, and the value range of H2 is 0.20mm-0.35mm. That is, the thickness of the package structure of a single filter chip including the sound absorbing layer 500 in this embodiment is in the range of 0.20mm-0.35mm. In other words, the thickness accuracy of the package structure in this embodiment can be controlled to 0.35mm or even less.

[0092] It should be understood that the isolation layer 300 formed in this embodiment may also be Figure 4 The structure shown, that is Figure 3 and Figure 4 The corresponding packaging method process is the same and will not be repeated here.

[0093] In summary, the filter packaging structure provided by the present invention includes a substrate, at least one filter chip, a plastic encapsulation layer, and a sound-absorbing layer. The filter chip is disposed on the substrate, with the front surface of the filter chip facing the substrate and a gap between the filter chip and the substrate. The plastic encapsulation layer covers the sidewalls of the filter chip and the substrate surface on both sides of the filter chip to enclose the gap, thereby forming a sealed cavity between the filter chip and the substrate. The sound-absorbing layer spans the filter chip and the plastic encapsulation layer to cover the back surface of the filter chip and the top surface of the plastic encapsulation layer.

[0094] Because the present invention, based on the different material fluidity of the plastic encapsulation layer, forms an isolation layer to separate the plastic encapsulation layer from the cavity below the filter chip before forming the plastic encapsulation layer of the thermosetting plastic encapsulation material containing inorganic fillers using the C-mold process, or directly forms the plastic encapsulation layer of the thermoplastic plastic encapsulation material containing inorganic fillers using vacuum lamination (without forming the isolation layer), and then thins the thickness of the package structure through a full grinding process before or before performing the splitting. This ensures that the thickness of the package structure reaches the target accuracy without changing the traditional splitting method of the filter chip, and prevents the problem of excessive wafer warping. At the same time, it also avoids the purpose of the cavity being invaded by the plastic encapsulation material. In addition, because the back of the thinned filter chip in the packaging structure of the present invention is provided with a sound-absorbing layer, it can also avoid the problem of bulk wave reflection on the back of the filter chip resulting from the gradual thinning of the thickness of the existing filter chip packaging structure, which leads to filter performance failure.

[0095] Throughout this application, references to "one embodiment" or "some embodiments" mean that a feature, structure, or characteristic described in connection with that embodiment is included in at least one embodiment, or at least some embodiments, of the present application. Thus, the appearance of the phrases "in one embodiment" or "in some embodiments" throughout this application does not necessarily refer to the same embodiment or embodiments. Furthermore, in one or more embodiments, features, structures, or characteristics may be combined in any suitable combinations and / or subcombinations.

[0096] Although some specific embodiments of the present application have been described in detail by way of example, it will be understood by those skilled in the art that the above examples are for illustration only and are not intended to limit the scope of the present application. The various embodiments of the present application may be combined in any manner without departing from the spirit and scope of the present application. It will also be understood by those skilled in the art that various modifications may be made to the embodiments without departing from the scope and spirit of the present application. The scope of the present application is defined by the appended claims.

Claims

1. A packaging structure, characterized in that: include: substrate; a filter chip, disposed on the substrate, with the front surface of the filter chip facing the substrate and a gap between the filter chip and the substrate; The plastic packaging layer covers the side walls of the filter chip and the substrate surfaces on both sides of the filter chip to enclose the gap, so that a sealed cavity is formed between the filter chip and the substrate.

2. The packaging structure according to claim 1, wherein: Also includes: The sound absorbing layer spans over the filter chip and the plastic packaging layer to cover the back surface of the filter chip and the top surface of the plastic packaging layer.

3. The packaging structure according to claim 2, wherein: Also includes: The isolation layer includes a continuous first portion and a second portion, wherein the first portion is located between the plastic packaging layer, the filter chip and the cavity, and the second portion is located between the plastic packaging layer and the substrate thereunder.

4. The packaging structure according to claim 3, wherein: The top surface of the plastic sealing layer and the top surface of the first portion of the isolation layer are located at the same level.

5. The packaging structure according to claim 4, wherein: In the vertical direction, the height of the first portion of the isolation layer is equal to the sum of the heights of the second portion thereof and the plastic packaging layer.

6. The packaging structure according to claim 1, wherein: Also includes: A plurality of bumps are located between the filter chip and the substrate.

7. The packaging structure according to claim 1, wherein: The material of the plastic sealing layer is a thermosetting or thermoplastic plastic sealing material containing inorganic fillers, and the inorganic fillers are one or a combination of aluminum oxide, titanium oxide, silicon nitride, aluminum nitride and silicon dioxide.

8. The packaging structure according to claim 2, wherein: The material of the sound absorbing layer is an organic material containing a sound absorbing filler, or an inorganic material or a metal material having a sound absorbing property, and the sound absorbing filler is a material having a relatively high acoustic impedance.

9. The packaging structure according to claim 1, wherein: The thickness of the packaging structure ranges from 0.20 mm to 0.35 mm.

10. The packaging structure according to claim 1, wherein: The filter chip is an acoustic wave filter chip, or a solid-state assembled bulk wave filter chip.

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