Electronic component

Abstract

An electronic component (100) includes a substrate (110), a functional element (120) formed on the substrate (110), a support body (140), a cover portion (150), and a protective layer (160) covering the cover portion (150). The support body (140) is disposed around a region of the substrate (110) in which the functional element (120) is formed. The cover portion (150) is disposed opposite the substrate (110) and is supported by the support body (140). A hollow space (190) is formed by the substrate (110), the support body (140), and the cover portion (150). The functional element (120) is formed inside the hollow space (190). If a surface of the support body (140) opposite a surface of the substrate (110) is defined as a first surface (141), a portion of the protective layer (160) contacts the first surface (141) of the support body (140) without the cover portion (150).

Description

Technical Field

[0001] This disclosure relates to electronic components, and more specifically, to the construction of electronic components having a WLP (Wafer Level Package) structure and functional elements formed in a hollow space. Background Technology

[0002] Japanese Patent No. 5849130 (Patent Document 1), Japanese Unexamined Patent Application Publication No. 2013-135264 (Patent Document 2), and Japanese Unexamined Patent Application Publication No. 2018-207524 (Patent Document 3) disclose surface acoustic wave (SAW) devices having a WLP structure and comb-shaped (IDT: Interdigital Transducer) electrodes disposed on a piezoelectric substrate. In such elastic wave devices, a hollow space is formed within the device in order to excite the IDT electrodes on the piezoelectric substrate.

[0003] In addition, a protective layer (insulating layer, sealing film) is sometimes provided on the upper surface of the cover that forms the hollow space to improve insulation and / or moisture resistance.

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent No. 5849130

[0007] Patent Document 2: Japanese Patent Application Publication No. 2013-135264

[0008] Patent Document 3: Japanese Patent Application Publication No. 2018-207524 Summary of the Invention

[0009] The technical problem that the invention aims to solve

[0010] In electronic components such as the elastic wave device described in the aforementioned patent documents, a connecting electrode is required to connect a functional element (IDT electrode) disposed in a hollow space to an external device. Generally, such a connecting electrode is formed by creating a through-hole in a protective layer, a cover, and a support for supporting the cover, and filling the through-hole with a metal conductor. However, if peeling or other defects occur between the protective layer and the cover, causing a decrease in the interfacial adhesion, the protective properties of the protective layer may decrease.

[0011] This disclosure was made to solve such a technical problem, and its purpose is to improve the adhesion of the protective layer formed on the electronic component and suppress the decline of the protective characteristics, wherein the electronic component has functional elements arranged in a hollow space.

[0012] Technical solutions for solving technical problems

[0013] The electronic component disclosed herein includes a substrate, functional elements formed on the substrate, a support, a cover, and a protective layer covering the cover. The support is disposed on the substrate around the area where the functional elements are formed. The cover is disposed opposite to the substrate and supported by the support. A hollow space is formed by the substrate, the support, and the cover. The functional elements are formed inside the hollow space. If the surface of the support opposite to the substrate side is designated as a first surface, a portion of the protective layer is in contact with the first surface of the support without being separated from the cover.

[0014] Invention Effects

[0015] According to the electronic component disclosed herein, a portion of the protective layer covering the cover portion is directly connected to the support without being separated from the cover portion. That is, the protective layer includes a region where the cover portion is disposed between it and the support, and a region directly in contact with the support. By configuring it in this way, the adhesion of the protective layer can be improved compared to a structure where the protective layer is only in contact with the cover portion. Therefore, the degradation of protective properties caused by the protective layer can be suppressed. Attached Figure Description

[0016] Figure 1 This is a top view of the electronic components involved in the implementation method.

[0017] Figure 2 It is along Figure 1 Sectional view of line II-II.

[0018] Figure 3 It is along Figure 1 Sectional view of line III-III.

[0019] Figure 4 It is along Figure 1 A sectional view of line IV-IV.

[0020] Figure 5 This is a top view of the cover portion of the electronic component involved in the embodiment. Detailed Implementation

[0021] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Furthermore, the same or corresponding reference numerals used to label the same parts in the drawings will not be described again.

[0022] Figure 1This is a top view of the electronic component 100 according to the embodiment. Furthermore, Figure 2 yes Figure 1 Sectional view along line II-II in the middle. Figure 3 yes Figure 1 The sectional view along line III-III, and further, Figure 4 yes Figure 1 A sectional view along line IV-IV.

[0023] Reference Figures 1-4 The electronic component 100 includes a substrate 110, a functional element 120, a support 140, a cover 150, a protective layer 160, and a connection electrode 170 formed within the support 140. In this embodiment, the electronic component 100 will be described as a surface acoustic wave (SAW) device. Therefore, an example will be provided where a piezoelectric substrate is used as the substrate 110 and an IDT electrode is included as the functional element 120. Hereinafter, the substrate 110 will sometimes be referred to as "piezoelectric substrate 110".

[0024] When viewed from the normal direction of the substrate 110, the electronic component 100 is formed in a generally rectangular shape. In each figure, the normal direction of the substrate 110 is defined as the Z-axis, the direction along one side when viewed from above is defined as the X-axis, and the direction along the side orthogonal to the X-axis is defined as the Y-axis. Furthermore, in each figure, the positive direction of the Z-axis is sometimes referred to as the upper surface side, and the negative direction is sometimes referred to as the lower surface side.

[0025] The piezoelectric substrate 110 is formed, for example, from a piezoelectric single-crystal material such as lithium tantalate (LiTaO3), lithium niobate (LiNbO3), alumina, silicon (Si), or sapphire, or from a piezoelectric multilayer material containing LiTaO3 or LiNbO3. A plurality of functional elements 120 are disposed on the upper surface 111 of the piezoelectric substrate 110. Each functional element 120 includes a pair of IDT electrodes, which are formed, for example, from an electrode material containing at least one of aluminum, copper, silver, gold, titanium, tungsten, platinum, chromium, nickel, or molybdenum, or an alloy thereof as a main component. A surface acoustic wave (SAW) resonator is formed by the piezoelectric substrate 110 and the functional elements (IDT electrodes) 120.

[0026] The upper surface 111 of the functional element 120 is formed in the piezoelectric substrate 110, and wiring electrodes 130 are formed for electrically connecting the functional elements 120 to each other and to the connecting electrodes 170.

[0027] The support 140 is formed as a wall surrounding the functional element 120 and protrudes from the upper surface 111 of the piezoelectric substrate 110 in the positive Z-axis direction. The support 140 is formed of an insulating resin such as epoxy or polyimide.

[0028] The cover portion 150 is supported by the support body 140 and is disposed opposite to the upper surface 111 of the piezoelectric substrate 110. The cover portion 150 is formed, for example, of an insulating resin material whose main components are epoxy, polyimide, acrylic, urethane, etc. In addition, the cover portion 150 may also use a portion of metal in addition to the above-mentioned resin. A hollow space 190 is formed by the piezoelectric substrate 110, the support body 140, and the cover portion 150. The functional element 120 is disposed within the hollow space 190.

[0029] A protective layer 160 is formed on the upper surface of the cover portion 150 (the surface opposite to the hollow space 190) to cover the cover portion 150. The protective layer 160 is configured to improve the insulation, moisture resistance, and voltage resistance of the electronic component 100. The protective layer 160 is formed of an insulating resin such as epoxy or polyimide.

[0030] The connection electrode 170 is formed by filling or plating conductive materials such as copper into through holes formed in the support 140, the cover 150, and the protective layer 160. The connection electrode 170 is electrically connected to the functional element 120 via the wiring electrode 130. Furthermore, the connection electrode 170 is also electrically connected to a terminal electrode 175 disposed on the upper surface of the support 140. The terminal electrode 175 is electrically connected to an external device or mounting substrate (not shown) using a connection member such as a solder ball 180. Additionally, a redistribution layer 165 may be formed between the cover 150 and the protective layer 160.

[0031] Figure 5 This is a top view of the cover portion 150 with the protective layer 160 removed. Viewed from the Z-axis, the cover portion 150 is formed as a whole in a generally rectangular shape. Multiple notches 200 are formed at the outer peripheral ends of the cover portion 150. If the surface of the support body 140 opposite to the surface of the substrate 110 is designated as the first surface 141, then in the portion where the notches 200 are formed, as shown... Figure 2 as well as Figure 4 As shown in the cross-sectional view, the protective layer 160 is directly connected to the first surface 141 of the support 140 without any separation from the cover portion 150. That is, the protective layer 160 includes: Figure 3 The area where the cover 150 is arranged between the support body 140 and the cross-sectional view, and as shown in the figure. Figure 2 as well as Figure 4 The area directly in contact with the support 140, as shown in the cross-sectional view. Furthermore, to improve adhesion, the protective layer 160 and the support 140 are preferably formed of the same material.

[0032] Viewed from above the cover portion 150 along the Z-axis, the notch portion 200 is formed at a position that is linearly symmetrical with respect to the virtual line CL1, which passes through the center SP of the piezoelectric substrate 110 and is parallel to one edge of the piezoelectric substrate 110. Alternatively, or otherwise, the notch portion 200 is formed at a position that is point-symmetrical with respect to the center SP of the piezoelectric substrate 110. By symmetrically arranging the notch portion 200 in this way, the symmetry of the adhesion between the protective layer 160 and the cover portion 150 or the support 140 is improved, thereby suppressing peeling caused by deformation due to differences in adhesion.

[0033] In such electronic components, functional elements disposed in the hollow space are electrically connected to external devices via connecting electrodes. As described above, the connecting electrodes are formed by filling conductive members into through holes formed in the protective layer, cover, and support. When machining the through holes, filling the conductive members, or heating the solder balls to mount the electronic component onto the mounting substrate, mechanical or thermal loads are applied to the interfaces of their laminated structures, sometimes causing delamination at the interfaces. In particular, if the protective layer delaminates, moisture may seep into the hollow space from the delaminated area, becoming a major cause of corrosion of the functional elements, or insulation may decrease, resulting in a deterioration of electrical characteristics.

[0034] In the electronic component 100 involved in this embodiment, such as Figure 5 As shown, a plurality of notches 200 are formed on the outer peripheral end face of the cover portion 150. In the portion of the notch 200, the protective layer 160 is directly connected to the first surface 141 of the support 140 without any separation from the cover portion 150. Therefore, even assuming that a portion of the interface between the cover portion 150 and the protective layer 160 peels off, the protective layer 160 can maintain overall tightness of contact with the support 140 through its direct connection to the support 140. Furthermore, with the notches 200 formed, the contact area between the protective layer 160 and the cover portion 150 is increased by the side portion of the notch 200. In addition, due to the curing shrinkage during the formation of the protective layer 160, a force in the direction of pushing the protective layer 160 towards the cover portion 150 acts on the notch 200. Therefore, compared to the case without the notches 200, the tightness of contact between the protective layer 160 and the cover portion 150 is increased.

[0035] Furthermore, when the protective layer 160 is connected to the piezoelectric substrate 110, stress concentration may occur at the interface between the protective layer 160 and the piezoelectric substrate 110, potentially causing cracks in the piezoelectric substrate 110. However, in this embodiment, the protective layer 160 is not connected to the piezoelectric substrate 110, thus suppressing the generation of cracks in the piezoelectric substrate 110.

[0036] Furthermore, as mentioned above, peeling of the protective layer 160 is prone to occur when the connection electrode 170 is formed and when the electronic component 100 is mounted. That is, peeling is prone to occur near the connection electrode 170. Therefore, it is preferable that the notch 200 is formed close to the connection electrode 170.

[0037] Furthermore, the corners of the electronic component 100 are prone to external mechanical contact, thus increasing the likelihood of peeling. Therefore, it is preferable to form a notch 200 at the corners of the electronic component 100.

[0038] Furthermore, while the above description used a surface acoustic wave (SAW) device as an example, the structure disclosed herein can be applied to electronic components other than SAW devices, as long as a hollow space is formed inside the component and functional elements are arranged within that hollow space. For example, it could be a bulk acoustic wave (BAW) device or a MEMS device that forms a small sensor or actuator.

[0039] The embodiments disclosed herein should be considered illustrative rather than restrictive in all respects. The scope of this disclosure is set forth not by the description of the embodiments above but by the claims, and is intended to include all modifications equivalent to and within the scope of the claims.

[0040] Explanation of reference numerals in the attached figures

[0041] 100 Electronic component, 110 Substrate, 111 Upper surface, 120 Functional element, 130 Wiring electrode, 140 Support, 141 First surface, 150 Cover, 160 Protective layer, 165 Rewiring layer, 170 Connecting electrode, 175 Terminal electrode, 180 Solder ball, 190 Hollow space, 200 Notch.

Claims

1. An electronic component, comprising: substrate; Functional elements are formed on the substrate; A support body is disposed on the substrate around the region where the functional element is formed; The cover portion is disposed opposite to the substrate and is supported by the support body; A protective layer is applied to cover the covered portion; and A connecting electrode, penetrating the protective layer, the cover, and the support, is used to electrically connect external devices and the functional components. A hollow space is formed by the substrate, the support, and the cover. The functional element is formed inside the hollow space. If the surface of the support body opposite to the surface of the substrate is designated as the first surface, then a portion of the protective layer is in contact with the first surface of the support body without being separated from the covering portion.

2. The electronic component according to claim 1, wherein, Multiple notches are formed at the outer peripheral end of the cover, and the protective layer and the support body are in contact at each notch.

3. The electronic component according to claim 2, wherein, The plurality of notches are formed near the connection electrode.

4. The electronic component according to claim 2, wherein, When the electronic component is viewed from the normal direction of the substrate, the plurality of notches are formed at the corners of the cover.

5. The electronic component according to any one of claims 2 to 4, wherein, When the electronic component is viewed from the normal direction of the substrate, The substrate is formed in a rectangular shape. The plurality of notches are formed at positions symmetrical to the virtual line, which passes through the center of the substrate and is parallel to one side of the substrate.

6. The electronic component according to any one of claims 2 to 4, wherein, When the electronic component is viewed from the normal direction of the substrate, The substrate is formed in a rectangular shape. The plurality of notches are formed at positions symmetrical with respect to the center point of the substrate.

7. The electronic component according to any one of claims 1 to 4, wherein, The protective layer and the support are formed of the same material.

8. The electronic component according to any one of claims 1 to 4, wherein, It also includes a redistribution layer formed between the cover and the protective layer.

9. The electronic component according to any one of claims 1 to 4, wherein, The substrate is a piezoelectric substrate. The functional element includes an interdigital transducer (IDT) electrode. A surface acoustic wave resonator is formed by the piezoelectric substrate and the IDT electrode.

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