Low-impedance miniaturized tuning fork wafer and manufacturing method thereof
By designing the side walls of curved surface grooves that are protruding opposite to each other on the vibrating arm of the tuning fork wafer to increase the electrode area, the problem of the miniaturized tuning fork wafer is difficult to reduce volume while maintaining low impedance, and the effect of smaller volume and simplifying the preparation process is achieved.
Patent Information
- Application Number
- CN202411686585.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-25
- Publication Date
- 2025-03-11
AI Technical Summary
The existing miniaturized tuning fork wafers are difficult to further reduce the volume while maintaining low impedance, especially in the preparation process, and traditional rectangular grooves cannot meet the requirements of low impedance.
By opening a groove on the vibrating arm of the tuning fork wafer and designing the side walls of the groove into an arc-shaped curved surface that convexly protrudes opposite, the area of the groove side walls is increased, thereby increasing the electrode area and reducing impedance. This design not only simplifies the preparation process, but also reduces the volume of the tuning fork wafer without increasing impedance.
The tuning fork wafer volume is further reduced under the same impedance, which is suitable for the needs of the smaller volume tuning fork wafer field, while simplifying the preparation process and reducing production difficulty.
Smart Images
Figure CN119602743A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of piezoelectric devices, and in particular to a low-impedance miniaturized tuning fork chip and a manufacturing method thereof. Background Art
[0002] As electronic products continue to become smaller and thinner, higher requirements are placed on the size of crystal oscillators. Miniaturized tuning fork chips can reduce the size and weight of electronic products, improve product portability and user experience. This is an important means to improve product competitiveness for electronic product companies such as mobile phone manufacturers and tablet computer manufacturers that pursue thin and light designs.
[0003] The tuning fork chip is made by opening a groove on the vibration arm, setting an electrode in the groove, and generating an electric field in the groove when the electrode is energized. The larger the electric field area, the higher the electric field efficiency, which makes the impedance value of the tuning fork chip smaller. However, the area of the electric field depends on the depth and length of the groove. The depth and length of small tuning fork chips are relatively small. The traditional rectangular groove cannot meet the low impedance requirements of miniaturized tuning fork chips.
[0004] Patent CN116094486A discloses a tuning fork crystal oscillator, a manufacturing method thereof, and a piezoelectric device. By setting a step-shaped groove, the polarization electric field area is increased, the vibration impedance is improved, and the groove is set to be symmetrical along the X direction by multiple photolithography, which improves the vibration symmetry of the tuning fork arm, thereby reducing the impedance. However, the preparation process of the step-shaped groove is difficult, especially for a smaller miniaturized tuning fork chip, it is more difficult to etch the step-shaped groove, and the electric field directions generated by the electrodes in the horizontal and vertical directions are different, which has a smaller effect on reducing the impedance. Therefore, a structure is needed to increase the area of the side wall of the groove, thereby reducing the impedance of the tuning fork chip, thereby reducing the volume of the tuning fork chip to meet the field demand for smaller tuning fork chips. Summary of the invention
[0005] The purpose of the present invention is to solve the problem of how to reduce the volume of a tuning fork oscillator without increasing impedance, and to provide a low-impedance miniaturized tuning fork chip and a method for manufacturing the same.
[0006] The purpose of the present invention can be achieved through the following technical solutions:
[0007] A low-impedance miniaturized tuning fork chip comprises a vibration arm, a base, a support arm, a connecting electrode slot and a groove.
[0008] The base is symmetrically provided with two vibration arms about the central axis of the base, and the base on both sides of the vibration arms is also symmetrically provided with two support arms.
[0009] Grooves are provided on the upper and lower sides of the two vibration arms along the length direction of the vibration arms. The grooves on the upper and lower sides have the same depth and do not penetrate the vibration arms. Connection electrode grooves are provided on the vibration arms around the grooves.
[0010] The side walls of the groove on both sides along the length direction are arc-shaped curved surfaces convex toward each other.
[0011] Furthermore, the base, the vibration arm and the support arm are all made of quartz.
[0012] Furthermore, the bottom of the groove is also an arc-shaped surface.
[0013] A method for preparing a low-impedance miniaturized tuning fork chip comprises the following steps:
[0014] Step 1: Plate a metal film on the front and back surfaces of the vibration arm at the groove position of the tuning fork chip.
[0015] Step 2: coating photoresist on the tuning fork wafer coated with the metal film.
[0016] Step 3: Expose and develop the location of the groove on the tuning fork wafer coated with photoresist, and display an arc-shaped pattern with two sides convex toward each other on the vibration arm to be etched.
[0017] Step 4: Use gold etching solution and chromium etching solution to perform metal etching on the exposed area in turn to expose the surface of the tuning fork wafer to be corroded.
[0018] Step 5: stripping and removing the photoresist on the surface of the quartz wafer.
[0019] Step 6: Use a corrosive solution to corrode the developed area, etch the arc-shaped pattern exposed by the metal etching downward, etch out a groove, and obtain a low-impedance miniaturized tuning fork chip.
[0020] Furthermore, in step 1, the method of coating the metal film is magnetron sputtering or evaporation coating, and the steps of coating the metal film are: first coating 20-50nm of chromium metal, and then coating 200-300nm of gold metal.
[0021] Furthermore, the arcs on both sides of the arc-shaped figure in step three are hyperbolas.
[0022] Furthermore, in step six, the etching solution is obtained by mixing hydrofluoric acid and ammonium fluoride in a molar concentration ratio of 3:2.
[0023] Furthermore, in step six, the temperature of the etching solution is 70-80° C., the etching time is 40-60 min, and the flow rate is 15-20 L / min.
[0024] Beneficial effects of the present invention:
[0025] The low-impedance miniaturized tuning fork chip prepared by the present invention increases the area of the side wall of the groove by setting the side wall in the length direction of the groove into an arc shape, thereby increasing the area of the electrode in the groove. The increase in the electrode area enhances the field strength generated by the electrode, thereby effectively reducing the impedance of the tuning fork chip in principle, so that the tuning fork chip prepared by the present invention has a smaller volume under the same impedance, reducing the volume of the tuning fork chip, and is suitable for the field demand of smaller volume tuning fork chips; the manufacturing method of the present invention only needs to adjust the hyperbolic curvature of the developing area according to the demand, and it can be formed by etching once without repeated etching, and the preparation process is simple. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The present invention will be further described below in conjunction with the accompanying drawings.
[0027] Figure 1 It is a schematic diagram of the overall structure of the present invention;
[0028] Figure 2 is an axial sectional view of the present invention;
[0029] Figure 3 is a cross-sectional view of the groove of the present invention;
[0030] In the figure: 1, vibration arm; 2, base; 3, groove; 301, side wall; 302, bottom; 4, support arm; 5, connecting electrode groove; 6, electrode in the groove. DETAILED DESCRIPTION
[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0032] See also Figure 1-Figure 2 As shown, a low-impedance miniaturized tuning fork chip includes a vibration arm 1, a base 2, a groove 3, a support arm 4 and a connecting electrode groove 5.
[0033] The base 2 is symmetrically provided with two vibration arms 1 about the central axis of the base 2 , and the base 2 on both sides of the vibration arm 1 is also symmetrically provided with two support arms 4 . The base 2 , the vibration arm 1 and the support arms 4 are all made of quartz material.
[0034] Grooves 3 are provided on the upper and lower sides of the two vibration arms 1 along the length direction of the vibration arms 1 . The grooves 3 on the upper and lower sides have the same depth and do not penetrate the vibration arms 1 . Connection electrode grooves 5 are provided on the vibration arms 1 around the grooves 3 for placing connection electrodes.
[0035] The side walls 301 on both sides of the groove 3 along the length direction are arc-shaped curved surfaces convex toward each other. The arc-shaped curved surfaces have a shorter length than a rectangle of the same area, making the length of the groove 3 shorter, and the formed tuning fork chip is shorter and smaller in size. The bottom 302 of the groove 3 is also an arc-shaped curved surface.
[0036] The two sides of the vibration arm 1 where the side wall 301 of the groove 3 is located are also arc-shaped curved surfaces convex toward each other.
[0037] See also Figure 3 As shown, the in-groove electrode 6 plated along the side wall 301 and the bottom 302 of the groove 3 has the same area as the side wall 301 and the bottom 302 of the groove 3, and the area of the in-groove electrode 6 with an arcuate surface is larger than the area of the in-groove electrode 6 with a rectangular side wall 301 formed by the same length of the groove 3. Therefore, the electric field area formed by the in-groove electrode 6 with an arcuate surface when energized is larger, thereby reducing the impedance of the tuning fork chip.
[0038] A method for preparing a low-impedance miniaturized tuning fork chip comprises the following steps:
[0039] Step 1: Plate a metal film on the front and back surfaces of the vibration arm 1 at the groove 3 of the tuning fork wafer by magnetron sputtering or evaporation coating, first plate 20-50nm of chromium metal, and then plate 200-300nm of gold metal.
[0040] Step 2: coating photoresist on the tuning fork wafer coated with the metal film.
[0041] Step 3: Expose and develop the location of the groove 3 on the tuning fork wafer coated with photoresist, and display an arc-shaped figure with two sides convex toward each other on the vibration arm 1 to be etched, and the arc lines on both sides of the arc-shaped figure are hyperbolas.
[0042] Step 4: Use gold etching solution and chromium etching solution to perform metal etching on the exposed area in turn to expose the surface of the tuning fork wafer to be corroded.
[0043] Step 5: stripping and removing the photoresist on the surface of the quartz wafer.
[0044] Step 6: Mix hydrofluoric acid and ammonium fluoride in a molar concentration ratio of 3:2 to obtain a corrosion solution, and use the corrosion solution to corrode the developed area. The corrosion solution temperature is 70-80°C, the etching time is 40-60min, and the flow rate is 15-20L / min. The arc pattern exposed by the metal etching is etched downward to etch out the groove 3 to obtain a low-impedance miniaturized tuning fork chip.
[0045] When the etching solution is used for etching, the etching rate is determined by the temperature, the concentration of the etching solution and the contact area between the etching solution and the area to be etched in the groove. When the etching temperature and the concentration of the etching solution are constant, the downward etching rate of the arc-shaped pattern in the present invention is only affected by the contact area between the etching solution and the area to be etched. Since the trend of the influence of the etching rate and the contact area is approximately linear, the bottom of the groove obtained by the present invention is also curved, and the curve is similar to the hyperbolic curvature of the area to be etched. Therefore, according to the hyperbolic formula As well as the maximum width A of the area to be etched in the groove, the straight line length B corresponding to the groove arc length and the groove depth H, it is calculated that when the hyperbola has a depth of H, the groove side wall area S1 is the arc length × depth, that is, When the groove is rectangular, the area of the groove sidewall S2 is depth × length, that is, S2 = H * B, the bottom of the groove is approximately a hyperbola, and the projection S3 of the overlapping area of the groove bottom and the groove sidewall in the vertical direction is approximately a hyperbola and a straight line. The integral area of By substitution method, we can get Since the groove bottom side area S3 overlaps with the groove side wall area S1, an effective electric field cannot be formed, and the affected area is the projection area of the overlapping area in the vertical direction. Therefore, when S1-S2≥S3, at the same tuning fork chip volume, the miniaturized tuning fork chip produced by the present invention has a smaller impedance.
[0046] Substitute the conventional groove dimensions A:B:H=45:3:2 into the formula. The A and H values in the formulas S1, S2, and S3 are replaced by B, and the inequality between B and a is obtained. The inventors prepared quartz wafers based on the above theoretical values and tested the impedance values and found that when When the impedance is , it is significantly lower than that of the tuning fork piece with the same volume and rectangular groove.
[0047] The impedance performance of the miniaturized tuning fork chip was tested according to the hyperbola set with different a values. ck is a rectangular tuning fork chip with the same volume. The results are shown in Table 1:
[0048] Table 1
[0049]
[0050] The embodiments of the present invention are described in detail above, but the contents described are only preferred embodiments of the present invention and cannot be considered to limit the scope of implementation of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.
Claims
1. A low-impedance miniaturized tuning fork chip, comprising a vibration arm (1), a base (2), a support arm (4) and a connecting electrode groove (5), characterized in that: Also includes a groove (3); The base (2) is symmetrically provided with two vibration arms (1) about the central axis of the base (2), and the base (2) on both sides of the vibration arm (1) is also symmetrically provided with two support arms (4); Grooves (3) are provided on the upper and lower sides of the two vibration arms (1) along the length direction of the vibration arms (1); the grooves (3) on the upper and lower sides have the same depth and do not penetrate the vibration arms (1); and connecting electrode grooves (5) are provided on the vibration arms (1) around the grooves (3); The side walls (301) on both sides of the groove (3) along the length direction are arc-shaped curved surfaces convex toward each other.
2. A low impedance miniaturized tuning fork chip according to claim 1, characterized in that: The base (2), the vibration arm (1) and the support arm (4) are all made of quartz.
3. The low impedance miniaturized tuning fork chip according to claim 1, characterized in that: The bottom (302) of the groove (3) is also an arc-shaped surface.
4. The method for preparing a low-impedance miniaturized tuning fork chip according to claim 1, characterized in that: The steps include: Step 1, coating the front and back surfaces of the vibration arm (1) at the position of the groove (3) of the tuning fork wafer with a metal film; Step 2, coating photoresist on the tuning fork wafer coated with the metal film; Step 3, exposing and developing the location of the groove (3) on the tuning fork wafer coated with photoresist, so that an arc-shaped pattern with two sides convex toward each other appears on the vibration arm (1) to be etched; Step 4: Use gold etching solution and chromium etching solution to perform metal etching on the exposed area in turn to expose the surface of the tuning fork wafer to be etched; Step 5, stripping and removing the photoresist on the surface of the quartz wafer; Step 6: Use a corrosive solution to etch the developed area, etch the arc-shaped pattern exposed by the metal etching downward, etch out a groove (3), and obtain a low-impedance miniaturized tuning fork chip.
5. The method for preparing a low-impedance miniaturized tuning fork chip according to claim 4, characterized in that: The method of coating the metal film in step 1 is magnetron sputtering or evaporation coating, and the steps of coating the metal film are: first coating 20-50nm of chromium metal, and then coating 200-300nm of gold metal.
6. The method for preparing a low-impedance miniaturized tuning fork chip according to claim 4, characterized in that: The arcs on both sides of the arc-shaped figure in step three are hyperbolas.
7. The method for preparing a low-impedance miniaturized tuning fork chip according to claim 4, characterized in that: The etching solution in step six is obtained by mixing hydrofluoric acid and ammonium fluoride in a molar concentration ratio of 3:
2.
8. The method for preparing a low-impedance miniaturized tuning fork chip according to claim 4, characterized in that: In step six, the temperature of the etching solution is 70-80° C., the etching time is 40-60 min, and the flow rate is 15-20 L / min.