Sensor packaging structure, preparation method and electronic equipment

Abstract

The invention provides a sensor packaging structure and electronic equipment, and the structure comprises a substrate which is provided with a first sound hole penetrating through the substrate in the thickness direction of the substrate; the cover shell is arranged on the first side of the base plate, and the cover shell and the base plate are matched to form a containing cavity; the sensor assembly is arranged in the accommodating cavity; the waterproof membrane is arranged on the first side of the substrate, the waterproof membrane is located in the containing cavity, an effective area of the waterproof membrane corresponds to an opening of the first sound hole, and the area of the effective area is larger than that of the opening of the first sound hole; the distance between the first sound hole and the effective area is H1 in the axial direction of the first sound hole, the distance between the inner wall surface of the first sound hole and the edge of the effective area is L1 in the radial direction of the first sound hole, and the ratio of H1 to L1 is larger than 1: 8.

Description

Technical Field

[0001] The present application relates to the technical field of packaging structures, and more specifically, to a sensor packaging structure and a preparation method and an electronic device. Background Art

[0002] In the related art, a MEMS microphone sensor packaging structure usually has a relatively large waterproof membrane inside to achieve waterproof function. The waterproof membrane protects sensitive electronic components from damage by blocking external moisture from entering the sensor through the sound hole. However, the size of the sound hole of the existing microphone sensor packaging structure is relatively small compared to the effective area of ​​the waterproof membrane, so that the effective area of ​​the waterproof membrane is not fully utilized, resulting in a low signal-to-noise ratio, which limits the acoustic performance of the sensor. Summary of the invention

[0003] The present application provides a new technical solution for a sensor packaging structure, which can at least solve the problem of low acoustic performance of existing packaging structures.

[0004] The present application also provides a new technical solution for electronic equipment.

[0005] According to a first aspect of the present application, a sensor packaging structure is provided, comprising: a substrate, the substrate being provided with a first sound hole penetrating along the thickness direction thereof; a cover shell, the cover shell being provided on a first side of the substrate, the cover shell and the substrate cooperating to form a receiving cavity; a sensor assembly, the sensor assembly being provided in the receiving cavity; a waterproof membrane, the waterproof membrane being provided on a first side of the substrate, the waterproof membrane being located in the receiving cavity, the effective area of ​​the waterproof membrane corresponding to the opening of the first sound hole, the area of ​​the effective area being larger than the opening area of ​​the first sound hole; in the axial direction of the first sound hole, the distance between the first sound hole and the effective area is H1, and in the radial direction of the first sound hole, the distance between the inner wall surface of the first sound hole and the edge of the effective area is L1, and the ratio of H1 to L1 is greater than 1:8.

[0006] Optionally, a minimum radial dimension of the first sound hole is d1, 0.25 mm ≤ d1 ≤ 1 mm.

[0007] Optionally, the first sound hole is a circular hole or a rectangular hole.

[0008] Optionally, the first sound hole is a circular hole, and the diameter of the circular hole is 8 mm.

[0009] Optionally, a mounting groove is provided on the first side of the substrate, the first sound hole is provided at the bottom of the mounting groove, the waterproof membrane is provided in the mounting groove, and the sensor packaging structure further includes: a supporting plate, the supporting plate is provided at the open end of the mounting groove, the supporting plate is connected to the substrate, the supporting plate is provided with a second sound hole penetrating along its thickness direction, the second sound hole is connected to the mounting groove, the opening area of ​​the second sound hole is smaller than the area of ​​the effective area, the sensor assembly is provided on the side of the supporting plate away from the waterproof membrane, and the position of the sensor assembly corresponds to that of the second sound hole; in the axial direction of the first sound hole, the distance between the second sound hole and the effective area is H2, and in the radial direction of the first sound hole, the distance between the inner wall surface of the second sound hole and the edge of the effective area is L2, and the ratio of H2 to L2 is greater than 1:8.

[0010] Optionally, H1≤50um, and the ratio of H1 to L1 is 1:1, and / or H2≤50um, and the ratio of H2 to L2 is 1:1.

[0011] Optionally, the first sound hole is aligned with the center of the effective area, and / or the first sound hole is aligned with the center of the second sound hole.

[0012] Optionally, the first sound hole, the effective area and the second sound hole have the same shape.

[0013] Optionally, the first sound hole is a rectangular hole, the width of the rectangular hole is the minimum radial dimension of the first sound hole, the length of the rectangular hole is d2, and the ratio of d2 to d1 is 2 to 1:1.

[0014] According to a second aspect of the present application, an electronic device is provided, comprising the sensor packaging structure described in any one of the above items.

[0015] According to the sensor packaging structure of the present application, by controlling the ratio of H1 to L1 within a range greater than 1:8, the effective area of ​​the waterproof membrane can be fully utilized, thereby effectively improving the signal-to-noise ratio of the sensor packaging structure and further enhancing the acoustic performance of the sensor packaging structure.

[0016] Other features and advantages of the present application will become apparent from the following detailed description of exemplary embodiments of the present application with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0018] Figure 1 It is a structural schematic diagram of a sensor packaging structure according to an embodiment provided in the present application.

[0019] Reference numerals

[0020] 100. Sensor packaging structure;

[0021] 10. Base plate; 11. Mounting groove; 12. First sound hole;

[0022] 20. waterproof membrane; 21. support body; 22. membrane body;

[0023] 30. Support sheet; 31. Second sound hole;

[0024] 40. Sensor components; 41. MEMS chips; 42. ASIC chips;

[0025] 50. Cover. DETAILED DESCRIPTION

[0026] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that unless otherwise specifically stated, the relative arrangement of components and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application.

[0027] The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the present application, its application, or uses.

[0028] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered as part of the specification.

[0029] In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values.

[0030] It should be noted that like reference numerals and letters refer to similar items in the following figures, and therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0031] The sensor packaging structure 100 according to the embodiment of the present application is first described in detail below with reference to the drawings.

[0032] like Figure 1 As shown, the sensor packaging structure 100 according to the embodiment of the present application includes: a substrate 10 , a cover 50 , a sensor component 40 and a waterproof membrane 20 .

[0033] Specifically, the substrate 10 is provided with a first sound hole 12 extending through the substrate 10 in a thickness direction thereof, the cover shell 50 is provided on a first side of the substrate 10, the cover shell 50 cooperates with the substrate 10 to form a receiving cavity, the sensor assembly 40 is provided in the receiving cavity, the waterproof membrane 20 is provided on a first side of the substrate 10, the waterproof membrane 20 is located in the receiving cavity, the effective area of ​​the waterproof membrane 20 corresponds to the opening of the first sound hole 12, and the area of ​​the effective area is greater than the opening area of ​​the first sound hole 12; in the axial direction of the first sound hole 12, the distance between the first sound hole 12 and the effective area is H1, and in the radial direction of the first sound hole 12, the distance between the inner wall surface of the first sound hole 12 and the edge of the effective area is L1, and the ratio of H1 to L1 is greater than 1:8.

[0034] In other words, the sensor packaging structure 100 according to the embodiment of the present application is mainly composed of a substrate 10, a cover shell 50, a sensor assembly 40 and a waterproof membrane 20, wherein the substrate 10 can be a PCB board, and one side of the substrate 10 in its thickness direction is a first side, the cover shell 50 is fixedly connected to the first side of the substrate 10, and an accommodating cavity is formed by the inner wall surface of the cover shell 50 and the first side of the substrate 10. The substrate 10 is provided with a first sound hole 12 penetrating along its thickness direction at a position corresponding to the accommodating cavity, and the sensor assembly 40 and the waterproof membrane 20 are both arranged in the accommodating cavity.

[0035] The waterproof membrane 20 includes a support body 21 and a membrane body 22. The support body 21 is provided with a through channel penetrating along the thickness direction of the substrate 10. The membrane body 22 is provided at the first end of the through channel and is fixedly connected to the support body 21. The area corresponding to the membrane body 22 and the through channel constitutes an effective area of ​​the waterproof membrane 20, and the area of ​​the effective area is larger than the cross-sectional area of ​​the first sound hole 12. The second end of the through channel corresponds to the position of the first sound hole 12, and the support body 21 is fixedly connected to the substrate 10, so that the waterproof membrane 20 can cover the first sound hole 12, thereby preventing external moisture from entering the accommodating cavity.

[0036] In the axial direction of the first acoustic hole 12, the distance from the first acoustic hole 12 to the effective area is H1, and in the radial direction of the first acoustic hole 12, the distance from the inner wall surface of the first acoustic hole 12 to the edge of the effective area is L1. In the case where the size of the waterproof membrane 20 is fixed, if the ratio of H1 to L1 is too small, it means that the radial size of the first acoustic hole 12 is too small relative to the radial size of the effective area of ​​the waterproof membrane 20, and the area of ​​the effective area of ​​the waterproof membrane 20 cannot be fully utilized, resulting in a low signal-to-noise ratio of the sensor packaging structure 100. In order to avoid this situation, in this embodiment, the ratio of H1 to L1 is greater than 1:8. For example, the ratio of H1 to L1 can be 1:7, 1:6, 1:5, 1:4, 1:3, 1:2 and 1:1, etc. Within this range, the effective area of ​​the waterproof membrane 20 can be effectively utilized, and the signal-to-noise ratio of the sensor packaging structure 100 can be effectively improved, thereby effectively improving the acoustic performance of the sensor.

[0037] Therefore, according to the sensor packaging structure 100 provided in this embodiment, by controlling the ratio of H1 to L1 within a range greater than 1:8, the effective area of ​​the waterproof membrane 20 can be fully utilized, thereby effectively improving the signal-to-noise ratio of the sensor packaging structure 100 and further enhancing the acoustic performance of the sensor packaging structure 100.

[0038] In some embodiments of the present application, the minimum radial dimension of the first sound hole 12 is d1, and 0.25 mm ≤ d1 ≤ 1 mm.

[0039] Specifically, the first sound hole 12 can be a circular hole or a rectangular hole, and the rectangular hole can be a chamfered rectangular hole. When the first sound hole 12 is a circular hole, the diameter of the circular hole is the minimum radial dimension of the first sound hole 12; when the first sound hole 12 is a rectangular hole, the width of the rectangular hole is the minimum radial dimension of the first sound hole 12.

[0040] The larger the minimum radial dimension of the first acoustic hole 12, the higher the signal-to-noise ratio of the sensor packaging structure 100. However, if the minimum radial dimension of the first acoustic hole 12 is too large, the exposed area of ​​the waterproof membrane 20 will be too large, and the waterproof membrane 20 will be easily pierced by external sharp objects. In this embodiment, the minimum radial dimension d1 of the first acoustic hole 12 is set between 0.25mm and 1mm. For example, d1 can be 0.25mm, 0.4mm, 0.5mm, 0.6mm, 0.7mm, 0.8mm, 0.9mm and 1mm. Within this range, it can be ensured that the sensor packaging structure 100 has a good signal-to-noise ratio and the waterproof performance of the sensor packaging structure 100 can be guaranteed.

[0041] In some optional examples of the present application, the first sound hole 12 is a circular hole, and the diameter of the circular hole is 8 mm.

[0042] That is to say, the first sound hole 12 is a circular hole, and the diameter of the circular hole is the minimum radial dimension of the first sound hole 12. When the diameter of the circular hole is less than 0.8 mm, the signal-to-noise ratio of the sensor packaging structure 100 is relatively low. For example, when the diameter of the circular hole is 0.6 mm, the signal-to-noise ratio of the sensor packaging structure 100 is 0.2 dB lower than when the diameter is 0.8 mm. However, when the diameter of the circular hole is greater than 0.8 mm, the signal-to-noise ratio of the sensor packaging structure 100 is not improved. Instead, the exposed area of ​​the waterproof membrane 20 is increased, thereby increasing the risk of the waterproof membrane 20 being punctured by external sharp objects. In this example, the diameter of the circular hole is set to 0.8 mm. Using this size can not only maximize the signal-to-noise ratio of the sensor packaging structure 100, but also minimize the exposed area of ​​the waterproof membrane 20, thereby ensuring the waterproof performance of the sensor packaging structure 100.

[0043] Table 1:

[0044] First sound hole diameter Φ0.6mm Φ0.8mm L1 B B-100um H1 A(≥50um) A(≥50um) H1 / L1 0.223 0.403 Product signal-to-noise ratio C C+0.2dB

[0045] In some embodiments of the present application, a mounting groove 11 is provided on the first side of the substrate 10, a first sound hole 12 is provided at the bottom of the mounting groove 11, a waterproof membrane 20 is provided in the mounting groove 11, and the sensor packaging structure 100 further includes: a support sheet 30, the support sheet 30 is provided at the open end of the mounting groove 11, the support sheet 30 is connected to the substrate 10, the support sheet 30 is provided with a second sound hole 31 extending through the thickness direction thereof, the second sound hole 31 is connected to the mounting groove 11, an opening area of ​​the second sound hole 31 is smaller than an area of ​​an effective area, a sensor assembly 40 is provided on a side of the support sheet 30 away from the waterproof membrane 20, and the position of the sensor assembly 40 corresponds to that of the second sound hole 31; in the axial direction of the first sound hole 12, a distance between the second sound hole 31 and the effective area is H2, and in the radial direction of the first sound hole 12, a distance between the inner wall surface of the second sound hole 31 and the edge of the effective area is L2, and a ratio of H2 to L2 is greater than 1:8.

[0046] In other words, according to the embodiment of the present application, the first side of the substrate 10 is provided with a mounting groove 11, the mounting groove 11 is located in the accommodating cavity, the substrate 10 is provided with a first sound hole 12 penetrating along the thickness direction at the bottom of the mounting groove 11, the waterproof membrane 20 is arranged in the mounting groove 11, the support body 21 of the waterproof membrane 20 is fixedly connected to the bottom of the mounting groove 11, and the first side of the substrate 10 is fixedly connected with a support sheet 30 that blocks the opening of the mounting groove 11, the support sheet 30 is provided with a second sound hole 31 penetrating along the thickness direction, and the second sound hole 31 corresponds to the position of the mounting groove 11. The second sound hole 31 is smaller than the opening of the mounting groove 11, so as to provide the required installation position for the sensor assembly 40.

[0047] The sensor assembly 40 mainly includes a MEMS chip 41 and an ASIC chip 42. The MEMS chip 41 is provided with a vibration cavity penetrating along the thickness direction of the substrate 10. The MEMS chip 41 is fixedly connected to the side of the support plate 30 away from the mounting groove 11, and the vibration cavity of the MEMS chip 41 corresponds to the position of the second sound hole 31. The ASIC chip 42 is fixedly connected to the first side of the substrate 10.

[0048] Specifically, in the axial direction of the first acoustic hole 12, the distance from the second acoustic hole 31 to the effective area is H2, and in the radial direction of the first acoustic hole 12, the distance from the inner wall surface of the first acoustic hole 12 to the edge of the effective area is L2. In the case where the size of the waterproof membrane 20 is fixed, if the ratio of H1 to L1 is too small, it means that the radial size of the second acoustic hole 31 is too small relative to the radial size of the effective area of ​​the waterproof membrane 20, and the area of ​​the effective area of ​​the waterproof membrane 20 cannot be fully utilized, resulting in a low signal-to-noise ratio of the sensor packaging structure 100. In order to avoid this situation, in this embodiment, the ratio of H2 to L2 is greater than 1:8. For example, the ratio of H2 to L2 can be 1:7, 1:6, 1:5, 1:4, 1:3, 1:2 and 1:1, etc. Within this range, the effective area of ​​the waterproof membrane 20 can be effectively utilized, and the signal-to-noise ratio of the sensor packaging structure 100 can be effectively improved, thereby effectively improving the acoustic performance of the sensor packaging structure 100.

[0049] According to one embodiment of the present application, H1≤50um, the ratio of H1 to L1 is 1:1, and / or H2≤50um, the ratio of H2 to L2 is 1:1.

[0050] If H1≤50um, a small slit will be formed between the waterproof membrane 20 and the substrate 10. This slit will produce a large acoustic resistance, and because the sound waves are reflected multiple times in the slit, the absorption and loss of sound energy will increase. When the ratio of H1 to L1 is less than 1:1, it indicates that the relative proportion of the slit between the waterproof membrane 20 and the substrate 10 is too large, which will cause too much sound energy to be absorbed, resulting in a low signal-to-noise ratio of the sensor packaging structure 100. On the contrary, when the ratio of H1 to L1 is greater than 1:1, it indicates that the relative proportion of the slit between the waterproof membrane 20 and the substrate 10 is small, which is not conducive to absorbing the noise generated by the edge of the waterproof membrane 20, and also causes the signal-to-noise ratio of the sensor packaging structure 100 to be low. In this embodiment, the ratio of H1 to L1 is 1:1. Under this ratio, the signal-to-noise ratio of the sensor packaging structure 100 can be maintained at a better level, and the acoustic performance of the sensor packaging structure 100 can be effectively improved.

[0051] Furthermore, if H2≤50um, a small slit will be formed between the waterproof membrane 20 and the support sheet 30. This slit will produce a large acoustic resistance, and because the sound wave is reflected multiple times in the slit, the absorption and loss of sound energy will be increased. When the ratio of H2 to L2 is less than 1:1, it indicates that the relative proportion of the slit between the waterproof membrane 20 and the support sheet 30 is too large, which will cause too much sound energy to be absorbed, resulting in a low signal-to-noise ratio of the sensor packaging structure 100. On the contrary, when the ratio of H2 to L2 is greater than 1:1, it indicates that the relative proportion of the slit between the waterproof membrane 20 and the support sheet 30 is small, which is not conducive to absorbing the noise generated by the edge of the waterproof membrane 20, and also causes a low signal-to-noise ratio of the sensor packaging structure 100. In this embodiment, the ratio of H2 to L2 is 1:1. Under this ratio, the signal-to-noise ratio of the sensor packaging structure 100 can be maintained at a relatively good level, and the acoustic performance of the sensor packaging structure 100 can be effectively improved.

[0052] In some embodiments of the present application, the first sound hole 12 is aligned with the center of the effective area, and / or the first sound hole 12 is aligned with the center of the second sound hole 31 .

[0053] Specifically, in order to reduce the lateral acoustic resistance, the first acoustic hole 12 can be centrally aligned with the effective area of ​​the waterproof membrane 20, and the first acoustic hole 12 can be centrally aligned with the second acoustic hole 31, so that the first acoustic hole 12, the effective area of ​​the waterproof membrane 20 and the second acoustic hole 31 are centrally aligned. With this arrangement, the sound waves can be effectively transmitted to the sensor assembly 40, and the signal-to-noise ratio of the sensor packaging structure 100 can be effectively improved, thereby improving the acoustic performance of the sensor packaging structure 100.

[0054] According to an embodiment of the present application, the first sound hole 12 and the effective area have the same shape as the second sound hole 31 .

[0055] That is to say, the shapes of the first acoustic hole 12, the effective area and the second acoustic hole 31 are consistent. Specifically, if the first acoustic hole 12 is circular, the effective area will also be designed to be circular, and the second acoustic hole 31 will also be a circular hole. Similarly, if the first acoustic hole 12 is rectangular, the effective area will be designed to be a rectangle with the same aspect ratio as the first acoustic hole 12, and the second acoustic hole 31 will also be a rectangular hole. This setting is conducive to the transmission of sound waves and can effectively improve the acoustic performance of the sensor packaging structure 100.

[0056] According to an embodiment of the present application, the first sound hole 12 is a rectangular hole, the width of the rectangular hole is the minimum radial dimension of the first sound hole 12, the length of the rectangular hole is d2, and the ratio of d2 to d1 is 2 to 1:1.

[0057] Specifically, the first sound hole 12 is a rectangular hole, for example, a chamfered rectangular hole. The ratio of the width d1 and the length d2 of the rectangular hole has a significant effect on the resonance peak and the background noise in the audio frequency band. Specifically, if the ratio of d2 to d1 is greater than 2:1, that is, the length is twice the width or more, this will cause the sensor packaging structure 100 to be prone to resonance peaks in the audio frequency band and high background noise. In this embodiment, the ratio of d2 to d1 is between 1:1 and 2:1. Using this ratio range can effectively reduce the generation of resonance peaks, thereby effectively ensuring the acoustic performance of the sensor packaging structure 100.

[0058] In summary, according to the sensor packaging structure 100 provided in this embodiment, by controlling the ratio of H1 to L1 within a range greater than 1:8, the effective area of ​​the waterproof membrane 20 can be fully utilized, thereby effectively improving the signal-to-noise ratio of the sensor packaging structure 100 and further enhancing the acoustic performance of the sensor packaging structure 100.

[0059] The embodiment of the present application also provides an electronic device, including the electronic device of any of the above embodiments. Since the sensor packaging structure according to the embodiment of the application has the above technical effects, the electronic device according to the embodiment of the application also has the corresponding technical effects, which will not be described in detail in this embodiment.

[0060] Although some specific embodiments of the present application have been described in detail by way of example, it should be understood by those skilled in the art that the above examples are only for illustration, not for limiting the scope of the present application. It should be understood by those skilled in the art that the above embodiments may be modified 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 sensor packaging structure, characterized in that: include: A substrate, wherein the substrate is provided with a first sound hole penetrating along a thickness direction thereof; A cover shell, wherein the cover shell is disposed on a first side of the substrate, and the cover shell cooperates with the substrate to form a receiving cavity; A sensor component, wherein the sensor component is disposed in the accommodating cavity; A waterproof membrane, the waterproof membrane is disposed on the first side of the substrate, the waterproof membrane is located in the accommodating cavity, an effective area of ​​the waterproof membrane corresponds to the opening of the first sound hole, and an area of ​​the effective area is larger than an opening area of ​​the first sound hole; In the axial direction of the first sound hole, the distance between the first sound hole and the effective area is H1, and in the radial direction of the first sound hole, the distance between the inner wall surface of the first sound hole and the edge of the effective area is L1, and the ratio of H1 to L1 is greater than 1:

8.

2. The sensor packaging structure according to claim 1, characterized in that: The minimum radial dimension of the first sound hole is d1, 0.25 mm ≤ d1 ≤ 1 mm.

3. The sensor packaging structure according to claim 2, characterized in that: The first sound hole is a circular hole or a rectangular hole.

4. The sensor packaging structure according to claim 1, characterized in that: The first sound hole is a circular hole, and the diameter of the circular hole is 8 mm.

5. The sensor packaging structure according to claim 1, characterized in that: A mounting groove is provided on the first side of the substrate, the first sound hole is provided at the bottom of the mounting groove, the waterproof membrane is provided in the mounting groove, and the sensor packaging structure further includes: A support sheet, the support sheet is arranged at the open end of the mounting groove, the support sheet is connected to the substrate, the support sheet is provided with a second sound hole penetrating along the thickness direction thereof, the second sound hole is communicated with the mounting groove, The opening area of ​​the second sound hole is smaller than the area of ​​the effective area, the sensor assembly is arranged on a side of the support sheet away from the waterproof membrane, and the position of the sensor assembly corresponds to that of the second sound hole; In the axial direction of the first sound hole, the distance between the second sound hole and the effective area is H2, and in the radial direction of the first sound hole, the distance between the inner wall surface of the second sound hole and the edge of the effective area is L2, and the ratio of H2 to L2 is greater than 1:

8.

6. The sensor packaging structure according to claim 5, characterized in that: H1≤50um, the ratio of H1 to L1 is 1:1, and / or H2≤50um, the ratio of H2 to L2 is 1:

1.

7. The sensor packaging structure according to claim 5, characterized in that: The first sound hole is aligned with the center of the effective area, and / or the first sound hole is aligned with the center of the second sound hole.

8. The sensor packaging structure according to claim 5, characterized in that: The first sound hole, the effective area and the second sound hole have the same shape.

9. The sensor packaging structure according to claim 8, characterized in that: The first sound hole is a rectangular hole, the width of the rectangular hole is the minimum radial dimension of the first sound hole, the length of the rectangular hole is d2, and the ratio of d2 to d1 is 2 to 1:

1.

10. An electronic device, characterized in that: A sensor packaging structure comprising any one of claims 1 to 9.

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