Piezoelectric wafer for SAW filter

Abstract

The utility model relates to the technical field of SAW (Surface Acoustic Wave) filters, in particular to a piezoelectric wafer for an SAW filter, which comprises a substrate, a plurality of grooves are arranged on the back of the substrate, the grooves are arranged in parallel, the grooves extend along the chordwise direction of the substrate, and metal strips are filled in the grooves. The piezoelectric wafer for the SAW filter provided by the utility model is simple in structural design, the resistivity of the wafer is obviously reduced, and the external electromagnetic field interference resistance, the heat dissipation capability and the conductivity are greatly improved.

Description

Technical Field

[0001] This utility model relates to the field of SAW filter technology, and in particular to a piezoelectric wafer for SAW filters. Background Technology

[0002] SAW (Surface Acoustic Wave) filtering devices utilize surface acoustic waves to simulate electrical signals and are typically fabricated on the front side of structures such as single-crystal wafers or single-crystal thin-film substrates. Due to the high resistivity of existing piezoelectric single-crystal substrates, static charge easily accumulates during the fabrication of interdigital transducers (IDTs) and dicing processes, leading to product failure and reduced yield. Furthermore, the low thermal conductivity of existing piezoelectric single crystals makes it difficult to dissipate the heat generated by the IDTs on their surface during operation, resulting in temperature rise that not only affects device performance but also limits the power of SAW devices. Additionally, the poor conductivity and weak magnetic field immunity of existing piezoelectric single crystals also limit the power of SAW filtering devices. Utility Model Content

[0003] The technical problem to be solved by this utility model is to overcome the shortcomings of the prior art and provide a piezoelectric wafer for SAW filters that has a simple structural design, significantly reduces wafer resistivity, and greatly improves resistance to external electromagnetic interference, heat dissipation and conductivity.

[0004] The technical solution adopted by this utility model to solve its technical problem is: a piezoelectric wafer for SAW filters, including a substrate, a plurality of grooves are formed on the back side of the substrate, the plurality of grooves are arranged in parallel, the grooves extend along the chord direction of the substrate, and the grooves are filled with metal strips.

[0005] Furthermore, the depth of the groove is greater than half the thickness of the base and less than the thickness of the base.

[0006] Furthermore, the sum of the areas of the vertical projections of the plurality of grooves accounts for at least half of the area of ​​the back surface of the substrate.

[0007] Furthermore, the groove opening width is between 0.01 and 0.2 mm.

[0008] Furthermore, the groove opening width is 0.1 mm.

[0009] Furthermore, the bottom surface of the metal strip is flush with the back surface of the substrate.

[0010] Furthermore, the cross-section of the groove is rectangular or inverted trapezoidal.

[0011] Furthermore, the thermal conductivity of the metal strip is greater than that of the substrate.

[0012] Furthermore, the bottom and end faces of the metal strip are provided with several heat-conducting grooves.

[0013] Furthermore, some of the grooves are configured as a mesh.

[0014] The beneficial effects of this utility model are:

[0015] (1) By opening several grooves on the back of the substrate and filling the grooves with metal strips, this utility model avoids the accumulation of static charge during the fabrication of interdigital transducers and grinding wheel dicing, which significantly improves the product yield. At the same time, covering the bottom of the wafer with metal improves the SAW device's resistance to external electromagnetic interference, enhances the wafer's heat dissipation performance, and improves its conductivity, thereby increasing the power of the SAW device.

[0016] (2) By opening several heat-conducting grooves on the bottom and end faces of the metal strip, the heat dissipation area of ​​the metal strip is increased and the heat dissipation efficiency of the metal strip is improved, thereby further enhancing the thermal conductivity of the wafer. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is a schematic diagram of the structure of this utility model;

[0019] Figure 2 This is a bottom view of the present invention;

[0020] Figure 3 This is a cross-sectional view of the groove in this utility model;

[0021] Figure 4 This is a front view of the metal strip in this utility model.

[0022] In the diagram: 1. Base; 2. Groove; 3. Metal strip; 4. Thermal trench. Detailed Implementation

[0023] The present invention will now be further described with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the present invention in a schematic manner, and therefore only show the components relevant to the present invention.

[0024] Example 1

[0025] like Figure 1 and Figure 2As shown, a piezoelectric wafer for a SAW filter includes a substrate 1. Several grooves 2 are formed on the back side of the substrate 1, arranged in parallel. The grooves 2 extend chordally along the substrate 1, and are filled with metal strips 3. Specifically, the grooves 2 have a rectangular cross-section; the thermal conductivity of the metal strips 3 is greater than that of the substrate 1. The metal strips 3 are generally made of Cu, but can also be made of other metals such as Al, Ag, and Au.

[0026] By creating several grooves 2 on the back side of the substrate 1, and filling each groove 2 with metal strips 3, static charge accumulation during the fabrication of interdigital transducers and grinding wheel dicing is avoided, significantly improving product yield. At the same time, covering the bottom of the wafer with metal improves the SAW device's resistance to external electromagnetic interference, enhances the wafer's heat dissipation performance, and improves conductivity, thereby increasing the power of the SAW device.

[0027] It should be noted that in this application, the groove 2 extends along the chord direction of the base 1 and penetrates the base 1. On the one hand, this makes grooving easier, enabling multi-blade dicing machines to groove on the back side; on the other hand, it exposes the two ends of the metal strip 3, increasing the heat dissipation area of ​​the metal strip 3 and thus improving heat dissipation efficiency.

[0028] The depth of groove 2 is greater than half the thickness of substrate 1 but less than the thickness of substrate 1. The sum of the areas of the vertical projections of several grooves 2 occupies at least half of the back surface area of ​​substrate 1. This design, while ensuring the mechanical strength of substrate 1, further reduces wafer resistivity, improves anti-interference capability, and enhances heat dissipation efficiency. Specifically, the optimal depth of groove 2 is H-5*λ, where H is the wafer thickness and λ is the period of the interdigital transducer fabricated on the wafer surface.

[0029] The groove width of groove 2 is between 0.01 and 0.2 mm. Specifically, groove 2 can be grooved on the back side using a multi-blade dicing machine. The width of the dicing machine wheel is generally around 100 μm, so the groove width of groove 2 is generally preferably 0.1 mm.

[0030] The bottom surface of the metal strip 3 is flush with the back of the base 1. This design avoids the excessive volume caused by the bottom surface of the metal strip 3 protruding from the back of the base 1.

[0031] In this application, the grooves 2 may not be arranged in parallel, and the grooves 2 may also be arranged in a mesh pattern.

[0032] Example 2

[0033] This embodiment improves upon embodiment 1 by modifying groove 2, such as... Figure 3 As shown, in this embodiment, the cross-section of the groove 2 is an inverted trapezoid, thereby ensuring that the metal strip 3 is stably embedded in the groove 2.

[0034] Example 3

[0035] This embodiment adds a heat-conducting trench 4 to the basic embodiment 1, such as... Figure 4 As shown, several heat-conducting grooves 4 are formed on both the bottom and end faces of the metal strip 3. Forming these grooves increases the heat dissipation area of ​​the metal strip 3, improves its heat dissipation efficiency, and further enhances the thermal conductivity of the wafer.

[0036] The above embodiments are only for illustrating the technical concept and features of this utility model. Their purpose is to enable those skilled in the art to understand the content of this utility model and implement it. They should not be used to limit the protection scope of this utility model. All equivalent changes or modifications made in accordance with the spirit and essence of this utility model should be covered within the protection scope of this utility model.

Claims

1. A piezoelectric wafer for SAW filters, comprising a substrate (1), characterized in that: The back of the base (1) is provided with a plurality of grooves (2), the plurality of grooves (2) are arranged in parallel, the grooves (2) extend along the chord direction of the base (1), and the grooves (2) are filled with metal strips (3).

2. The piezoelectric wafer for SAW filter according to claim 1, characterized by: The depth of the groove (2) is greater than half the thickness of the base (1) and less than the thickness of the base (1).

3. The piezoelectric wafer for SAW filter according to claim 1, characterized by: The sum of the areas of the vertical projections of the grooves (2) shall account for at least half of the area of ​​the back surface of the base (1).

4. The piezoelectric wafer for SAW filter according to claim 1, characterized by: The groove (2) has a groove width of 0.01 to 0.2 mm.

5. The piezoelectric wafer for SAW filter according to claim 4, characterized by: The groove (2) has a groove width of 0.1 mm.

6. The piezoelectric wafer for SAW filter according to claim 1, characterized by: The bottom surface of the metal strip (3) is flush with the back surface of the base (1).

7. The piezoelectric wafer for SAW filter according to claim 1, characterized by: The cross-section of the groove (2) is rectangular or inverted trapezoidal.

8. The piezoelectric wafer for SAW filter according to claim 1, characterized by: The thermal conductivity of the metal strip (3) is greater than that of the substrate (1).

9. The piezoelectric wafer for SAW filter according to claim 1 or 8, characterized by: The bottom and end faces of the metal strip (3) are provided with several heat-conducting grooves (4).

10. The piezoelectric wafer for SAW filter according to claim 1, characterized by: Several of the grooves (2) are arranged in a mesh shape.

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