Filter structure

Abstract

The application relates to a filter structure, which comprises a substrate with oppositely arranged first and second surfaces, and a filter with a first part and a second part arranged at the first and second surfaces of the substrate respectively, wherein the first part and the second part are electrically connected through a through hole embedded in the substrate. The above technical solution can at least maintain the performance of a SAW filter in the process of miniaturization of the filter structure.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, and more specifically, to a filter structure. Background Technology

[0002] Wireless communication products involve signal reception and transmission. To ensure signal quality, different numbers of filters are used in system design. Surface acoustic wave (SAW) filters are one type of filter. Surface acoustic waves are mechanical waves with unique properties. When traveling along a crystal surface, their energy decays exponentially in the direction perpendicular to the crystal surface. When penetrating deeper than one wavelength, the energy density drops to 1 / 10 of that at the surface. Because the wave energy is concentrated on the crystal surface, surface acoustic wave components can easily utilize the energy they carry.

[0003] Surface acoustic waves can generally be excited using an interdigital transducer (IDT). An IDT can be composed of components with a thickness between [insert thickness here]. The aluminum electrodes are formed on the surface of a piezoelectric single crystal substrate using photolithography. When a voltage is applied to the positive and negative electrodes of the transducer, an electric field is generated between the interdigitates. The surface of the piezoelectric substrate is subjected to the electric field and vibrates synchronously to generate surface acoustic waves. When the distance between the interdigitates is equal to the wavelength of the surface acoustic waves, the efficiency of the generated surface acoustic waves is maximized. The efficiency of the SAW filter is directly related to its area. Unless there are new advances in process technology or materials science, reducing the area of ​​the SAW filter to minimize electronic components will not provide effective benefits. Summary of the Invention

[0004] To address the aforementioned problems in related technologies, this invention proposes a filter structure to maintain the performance of SAW filters during the miniaturization process of filter structures.

[0005] According to one aspect of the present invention, a filter structure is provided, comprising: a substrate having a first surface and a second surface disposed opposite to each other; and a filter having a first portion and a second portion, the first portion and the second portion being respectively disposed on the first surface and the second surface of the substrate. The first portion and the second portion are electrically connected through through-holes embedded in the substrate.

[0006] In some embodiments, the first surface and the second surface are respectively provided with a first pad and a second pad electrically connected to the through hole, wherein the first pad and the second pad are respectively connected to the first portion and the second portion.

[0007] In some embodiments, a first surface and a second surface are respectively provided with a molded material covering the first portion and the second portion. In some embodiments, one of the first surface and the second surface of the substrate is provided with a connector electrically connected to a through hole, wherein the connector is exposed by the molded material. In some embodiments, a protective layer is provided on the surface of the molded material.

[0008] In some embodiments, the areas of the first portion and the second portion are approximately the same.

[0009] In some embodiments, the filter is a surface acoustic wave filter. In some embodiments, the filter is formed of a plurality of transducer structures, a first portion comprising a portion of the plurality of transducer structures, and a second portion comprising another portion of the plurality of transducer structures.

[0010] In some embodiments, the through-holes include at least two through-holes offset from each other in the direction from the first surface to the second surface.

[0011] In some embodiments, either the first portion or the second portion includes a plurality of transducer structures, wherein traces for interconnecting at least a portion of the plurality of transducer structures are further provided at the respective first or second surface.

[0012] According to another aspect of the present invention, a filter structure is provided, comprising: a substrate having a first surface and a second surface disposed opposite to each other, and a through-hole and a ground wire embedded therein; and a filter having a first portion and a second portion, the first portion and the second portion being respectively disposed on the first surface and the second surface of the substrate. The first portion and the second portion are electrically connected through the through-hole, and an inductor is connected between the through-hole and the ground wire.

[0013] In some embodiments, the first surface and the second surface are respectively provided with a first pad and a second pad electrically connected to the through hole, wherein the first pad and the second pad are respectively connected to the first portion and the second portion.

[0014] In some embodiments, the filter structure further includes a molding compound covering the first portion and the second portion. In some embodiments, the filter structure further includes a connector located on one of the first and second surfaces of the substrate, wherein the connector is electrically connected to a through-hole and the connector is exposed by the molding compound. In some embodiments, the filter structure further includes a protective layer covering the surface of the molding compound remote from the substrate.

[0015] In some embodiments, the first portion and the second portion have approximately the same area.

[0016] In some embodiments, the filter is a surface acoustic wave filter. In some embodiments, the filter is formed of a plurality of transducer structures, a first portion comprising a portion of the plurality of transducer structures, and a second portion comprising another portion of the plurality of transducer structures.

[0017] In some embodiments, the through-holes include at least two through-holes offset from each other in the direction from the first surface to the second surface.

[0018] In some embodiments, either the first portion or the second portion includes a plurality of transducer structures, wherein traces for interconnecting at least a portion of the plurality of transducer structures are further provided at the respective first or second surface. Attached Figure Description

[0019] The various aspects of the invention will be best understood from the following detailed description when read in conjunction with the accompanying drawings. It should be noted that, according to standard industrial practice, the components are not drawn to scale. In fact, the dimensions of the components may be arbitrarily increased or decreased for clarity of discussion.

[0020] Figure 1A This is a schematic diagram of a filter structure according to an embodiment of the present invention.

[0021] Figure 1B It shows Figure 1A A magnified view of the second part of the image.

[0022] Figure 2 This is a circuit connection diagram of a filter having multiple transducers according to some embodiments of the present invention.

[0023] Figure 3A and Figure 3B This is a schematic diagram of an embodiment in which the filter is divided into two parts.

[0024] Figure 4 This is a three-dimensional schematic diagram of a filter structure according to an embodiment of the present invention.

[0025] Figure 5 This is a schematic diagram simulating the filtering effect of a filter structure according to an embodiment of the present invention.

[0026] Figure 6 This is a schematic diagram of a filter structure according to an embodiment of the present invention.

[0027] Figure 7 This is a schematic diagram simulating the filtering effect of a SAW filter with two transducers. Specific Implementation

[0028] The following disclosure provides numerous different embodiments or instances for implementing various features of the provided subject matter. Specific examples of elements and arrangements will be described below to simplify the invention. These are merely examples and are not intended to limit the invention. For example, in the following description, forming a first component above or on a second component can include embodiments where the first and second components are in direct contact, or embodiments where an additional component is formed between the first and second components such that the first and second components are not in direct contact. Furthermore, reference numerals and / or letters may be repeated throughout the various instances. Such repetition is for brevity and clarity only and does not in itself indicate a relationship between the various embodiments and / or configurations discussed.

[0029] An embodiment of the present invention provides a filter structure. Figure 1A This is a schematic diagram of a filter structure 100 according to an embodiment of the present invention. Figure 1A As shown, the filter structure 100 includes a substrate 110, which has a first surface (e.g., upper surface) 111 and a second surface (e.g., lower surface) 112 disposed opposite to each other. The present invention divides the filter 120 into a first portion 121 and a second portion 122, and the first portion 121 and the second portion 122 are respectively disposed on the first surface 111 and the second surface 112 of the substrate. In some embodiments, the areas of the first portion 121 and the second portion 122 may be substantially the same. In other embodiments, the filter 120 may be divided in any suitable manner, and the filter 120 may be divided into a first portion 121 and a second portion 122 with different areas. In some embodiments, the first portion 121 and the second portion 122 are disposed opposite to each other. In some embodiments, the filter 120 may be a SAW filter, and the first portion 121 and the second portion 122 may be two parts of a SAW filter.

[0030] The first portion 121 and the second portion 122 are electrically connected via through-holes 115 embedded in the substrate 110. In the illustrated embodiment, the through-holes 115 include at least two vias offset from each other in the direction from the first surface 111 to the second surface 121 for electrically connecting the first portion 121 and the second portion 122. In some embodiments, the first portion 121 and the second portion 122 may also be electrically connected via traces (not shown) embedded in the substrate 110. It should be understood that the first portion 121 and the second portion 122 can be electrically connected by any suitable configuration of through-holes and traces, and the present invention is not limited thereto.

[0031] The above-described technical solution of the present invention provides a double-sided surface acoustic wave (SAW) filter. In order to meet the progress of electronic component miniaturization, the SAW filter is mainly divided into a first part 121 and a second part 122 with comparable areas. The first part 121 and the second part 122 are respectively disposed on the first surface 111 and the second surface 112 on the upper and lower surfaces of the substrate 110. The first part 121 and the second part 122 are electrically connected through through holes 115 and traces embedded in the substrate 110, so as to reduce the substrate area occupied by the SAW filter without affecting the efficiency of the SAW filter.

[0032] Figure 1B It shows Figure 1A A magnified view of the second part of the document. (Reference) Figure 1B As shown, the second portion 122 may include a plurality of transducers 191 located on a substrate 190. The plurality of transducers 191 are covered by a capping layer 194, such as a dielectric material. The plurality of transducers 191 are located at the bottom of a cavity 195 defined by a wall 192 on the capping layer 194. A cap 198 is disposed above the wall 192, covering the cavity 195. Conductive posts 196 pass through the wall 192 and are electrically connected to the transducers 191 via a conductive material 199. Solder balls 197 are disposed on top of the conductive posts 196, thereby allowing the transducers 191 in the second portion 122 to be electrically connected to other components. The first portion of the filter may have a reference... Figure 1B Similar structures will not be described again here.

[0033] Return to reference Figure 1A The first surface 111 and the second surface 112 of the substrate 110 are respectively provided with a first pad 116 and a second pad 118 electrically connected to the through hole 115. The first pad 116 and the second pad 118 are respectively connected to the first part 121 and the second part 122 of the filter 120 through solder balls 119.

[0034] The first surface 111 and the second surface 112 are respectively provided with molded parts 140 covering the first portion 121 and the second portion 122. In the illustrated embodiment, a connector 149 is provided at the second surface 112 of the substrate 110. The connector 149 is electrically connected to the through hole 115. The connector 149 is exposed by the molded part 140. In addition, a protective layer 150 may be provided on the surface of the molded part 140. In the illustrated embodiment, the protective layer 150 covers the top surface and sidewalls of the molded part 140 on the first surface 111, and also extends to cover the sidewalls of the substrate 110 and the sidewalls of the molded part 140 at the second surface 112.

[0035] The filter structure 100 provided by this invention can mount segmented SAW filters onto the upper and lower surfaces (first surface 111 and second surface 112) of a substrate 110 using SMT (Surface Mount Technology). The first surface 111 and second surface 112 are electrically connected by vias 115 and traces embedded in the substrate 110, forming a double-side SAW filter. Furthermore, the first surface 111 and second surface 112 of the substrate 110 are molded using a molding compound 140, followed by dicing. Finally, a protective layer 150 is formed on the outside of the molding compound 140 using a sputtering process. The resulting double-side SAW filter occupies 50% less substrate area than a conventional single-side SAW filter.

[0036] Figure 2 This is a circuit connection diagram of a filter having multiple transducers (IDT, interdigital transducer) according to some embodiments of the present invention. Figure 3A and Figure 3B This is a schematic diagram of an embodiment where the filter is divided into two parts. Figure 2 In the example shown, filter 120 is formed by connecting seven transducers 191. Figure 3A and Figure 3B As shown, the seven transducers 191 can be divided into two parts. The first part 121 includes a portion of the multiple transducers (e.g., four of the seven transducers), and the second part 12 of the filter includes the remaining portion of the multiple transducer structure (e.g., the other three of the seven transducers). The multiple transducers 191 in the first part 121 and the multiple transducers 191 in the second part 122 are respectively disposed on the first surface 111 and the second surface 112 of the substrate 110 (see reference). Figure 1A The area occupied by a filter with 7 IDTs is approximately 811 × 516, and the filter with 7 IDTs described above can be divided into two parts of roughly equal area. In one embodiment, such as... Figure 3A The filter is divided into a first part 121 comprising four transducers 191, occupying an area of ​​approximately 400 × 546; and a second part 122 comprising three transducers 191, occupying an area of ​​approximately 400 × 431. In another embodiment, as... Figure 3BThe filter is divided into a first part 121 comprising three transducers 191, occupying an area of ​​approximately 400 x 400, and a second part 122 comprising four transducers 191, occupying an area of ​​approximately 400 x 694. In other embodiments, the filter may be divided in other suitable ways, and the areas of the resulting first part 121 and second part 122 may be approximately the same or different.

[0037] Figure 4 This is a three-dimensional schematic diagram of a filter structure according to an embodiment of the present invention. Figure 4 As shown, a plurality of transducers 191 of the filter are respectively disposed on a first surface (uppermost surface) 111 and a second surface (lowermost surface) 112. The transducers 191 on the first surface 111 can be connected to the transducers 191 on the second surface 112 through a plurality of through holes 115 extending in the vertical direction. Traces 114 for interconnecting at least some of the plurality of transducers 191 are also provided on the first surface 111 or the second surface 112.

[0038] Figure 5 These are simulation results of the filtering effect of the filter structure according to an embodiment of the present invention. Figure 5 The simulation results show that the filtering effect of the dual-sided SAW filter (shown by curve S51) is comparable to that of the single-sided SAW filter (shown by curve S52). Therefore, this invention divides the SAW filter into two parts, one part is mounted on the upper surface of the substrate, and the other part is mounted on the lower surface. Compared with the single-sided SAW filter, the dual-sided SAW filter can reduce the area by about 50%, and its performance is similar to or even better than that of the single-sided SAW filter.

[0039] On the other hand, impedance matching is crucial for high-frequency circuits. The Q-value of the inductor structure used in the matching circuit affects the losses in the high-frequency circuit. A higher Q-value in the inductor structure results in lower insertion loss for the SAW filter. Therefore, SAW filters typically connect an inductor structure mounted on the substrate surface to the output terminal to enhance the filtering effect. However, inductors mounted on the substrate surface are often too bulky, posing a problem in the miniaturization of electronic components. Therefore, in some embodiments, such as... Figure 6 The filter structure 200 shown further incorporates a through-hole embedded in the substrate 110 as a spiral inductor 160. This through-hole is connected to the first portion 121 and the second portion 122 of the filter 120 located on the first surface 111 and the second surface 112 of the substrate. As shown in Figure 6, the inductor 160 can be positioned at ground (GND). Figure 6 Other aspects of the filter structure 200 shown can be compared with the reference. Figure 1AThe content discussed is similar, and the same reference numerals are used for similar parts, so they will not be described again here.

[0040] This can further enhance the filtering effect of the SAW filter and filter out unwanted waves. For example... Figure 7 As shown, Figure 7 The SAW filter with two transducers is shown, where Zs is the internal transducer in series configuration and Zp is in parallel configuration. The waveform of Zs is represented by line segment S71, and the waveform of Zp is represented by line segment S72. The two are combined to form the filtered waveform S73, which is supplied with a frequency of [frequency value missing]. The wave passes through. Through-holes embedded inside the substrate act as a spiral inductor, which can filter the aforementioned waveform. Left side and Wave filtering on the right. In addition, by embedding the inductor structure, which was originally located on the substrate surface and electrically connected to the SAW filter, into the substrate, the substrate area occupied can be further reduced, thereby achieving miniaturization.

[0041] The foregoing summary outlines features of several embodiments that enable those skilled in the art to better understand various aspects of this disclosure. Those skilled in the art should understand that other processes and structures can be readily designed or modified based on this invention to achieve the same objectives and / or benefits as the embodiments described herein. Those skilled in the art should also recognize that these equivalent structures do not depart from the spirit and scope of the invention, and that various changes, substitutions, and modifications can be made without departing from the spirit and scope of the invention.

Claims

1. A filter structure, characterized in that, include: The substrate has a first surface and a second surface disposed opposite to each other; A filter having a first portion and a second portion, the first portion and the second portion being respectively disposed on the first surface and the second surface of the substrate; The first part and the second part are electrically connected through through-holes embedded in the substrate. The filter is a surface acoustic wave (SAW) filter. The first part and the second part are formed by dividing a single unilateral SAW filter. The filter is formed by multiple transducer structures. The first part includes a portion of the multiple transducer structures, and the second part includes the remaining portions of the multiple transducer structures. The plurality of transducer structures are covered by a cover layer and located at the bottom of a cavity defined by a wall above the cover layer, with a cap above the wall covering the cavity.

2. The filter structure according to claim 1, characterized in that, The first surface and the second surface are respectively provided with a first pad and a second pad electrically connected to the through hole, wherein the first pad and the second pad are respectively connected to the first part and the second part.

3. The filter structure according to claim 1, characterized in that, The first surface and the second surface are respectively provided with molded materials covering the first part and the second part.

4. The filter structure according to claim 3, characterized in that, One of the first surface and the second surface of the substrate is provided with a connector electrically connected to the through hole, wherein the connector is exposed by the molding.

5. The filter structure according to claim 3, characterized in that, The surface of the molded object is provided with a protective layer.

6. The filter structure according to claim 1, characterized in that, The areas of the first part and the second part are approximately the same.

7. The filter structure according to claim 1, characterized in that, The through-holes include at least two through-holes offset from each other in the direction from the first surface to the second surface.

8. The filter structure according to claim 1, characterized in that, Each of the first portion and the second portion includes a plurality of transducer structures, wherein traces for interconnecting at least a portion of the plurality of transducer structures are further provided at the corresponding first surface or second surface.

9. A filter structure, characterized in that, include: A substrate has a first surface and a second surface disposed opposite to each other, and a through hole and a ground wire are embedded in the substrate; A filter having a first portion and a second portion, the first portion and the second portion being respectively disposed on the first surface and the second surface of the substrate; The first part and the second part are electrically connected through the through hole, and an inductor is connected between the through hole and the grounding wire. The filter is a surface acoustic wave (SAW) filter, and the first and second parts are formed by dividing a single, one-sided SAW filter. One end of the inductor is electrically connected to the first part via a solder ball, and the other end of the inductor is electrically connected to the connection point of the through hole and the grounding wire.

10. The filter structure according to claim 9, characterized in that, The first surface and the second surface are respectively provided with a first pad and a second pad electrically connected to the through hole, wherein the first pad and the second pad are respectively connected to the first part and the second part.

11. The filter structure according to claim 9, characterized in that, Also includes: A molded material that covers the first portion and the second portion.

12. The filter structure according to claim 11, characterized in that, Also includes: A connector is located on one of the first and second surfaces of the substrate, wherein the connector is electrically connected to the through-hole and the connector is exposed by the molding.

13. The filter structure according to claim 11, characterized in that, Also includes: A protective layer covers the surface of the molded object that is away from the substrate.

14. The filter structure according to claim 9, characterized in that, The first part and the second part have approximately the same area.

15. The filter structure according to claim 9, characterized in that, The filter is formed by multiple transducer structures, the first part includes a portion of the multiple transducer structures, and the second part includes the remaining portion of the multiple transducer structures.

16. The filter structure according to claim 9, characterized in that, The through-holes include at least two through-holes offset from each other in the direction from the first surface to the second surface.

17. The filter structure according to claim 9, characterized in that, Each of the first portion and the second portion includes a plurality of transducer structures, wherein traces for interconnecting at least a portion of the plurality of transducer structures are further provided at the corresponding first surface or second surface.

Images