Quartz crystal etching solution and method for cutting quartz crystal tuning fork by laser

Abstract

The invention belongs to the technical field of laser processing, and provides a quartz crystal etching solution which comprises the following components in volume concentration: 10-30% of hydrofluoric acid, 1-5% of sulfuric acid, 0.1-0.3% of surfactant and the balance of water. By optimizing the proportion, the manufacturing precision and the production and manufacturing efficiency of the tuning fork wafer are improved. And the stable etching rate and the optimal etching surface are obtained, and meanwhile, the cost is saved for process replacement. The invention further provides a method for cutting the tuning fork of the quartz crystal through the laser. The method comprises the steps that S1, the cutting contour line of the tuning fork is preset on the quartz crystal; s2, performing laser cutting on the quartz crystal based on a preset cutting contour line, and forming a tuning fork contour on the quartz crystal; and S3, integrally soaking the quartz crystal in the quartz crystal etching solution, and separating out the tuning fork. The machining process of the quartz crystal tuning fork is simplified, the cutting quality is optimized, the method is suitable for the large-piece manufacturing process, and the cutting efficiency and the yield are greatly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser processing, and particularly relates to a quartz crystal etching solution and a method for laser cutting a quartz crystal tuning fork. Background Art

[0002] A tuning fork crystal oscillator refers to a crystal oscillator whose quartz wafer is shaped like a tuning fork and is another name for a cylindrical crystal oscillator. Tuning fork crystal oscillators are mainly used in timing electronic circuits, such as quartz watches, timers, air conditioner remote controls, clocks, etc. In fact, the vast majority of electronic products involving data processing require crystal oscillator components to provide them with clock frequencies, otherwise they cannot be started or operate effectively. Thus, it can be seen that crystal oscillators, especially tuning fork crystal oscillators, are very important components in electronic products. Secondly, as tuning fork crystal oscillators develop towards higher precision and higher stability, crystal oscillators are gradually miniaturized, thinned, and chip-sized, posing greater challenges to improving their precision and stability.

[0003] Traditional processing often uses a wire cutting machine to further cut the original material that has been cut into strip shapes into the shape of a tuning fork. Then, it is slightly etched to remove burrs and plated with electrodes through a silver plating process. The traditional process has cumbersome processing steps, low technical requirements, low precision, and low output. However, as the market's requirements for miniaturization and precision of electronic components are getting higher and higher, the traditional process has gradually encountered bottlenecks, and it has become very difficult to machine components smaller than 1 millimeter by mechanical processing. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems of low precision and low efficiency in tuning fork processing in the prior art.

[0005] To this end, the present invention provides a quartz crystal etching solution, which, in terms of volume concentration, includes 10% - 30% hydrofluoric acid, 1% - 5% sulfuric acid, 0.1% - 0.3% surfactant, and the balance is water.

[0006] The present invention also provides a method for laser cutting a quartz crystal tuning fork, including the following steps:

[0007] S1, preset a cutting contour line of the tuning fork on the quartz crystal;

[0008] S2, perform laser cutting on the quartz crystal based on the cutting contour line to form a tuning fork contour;

[0009] S3, immerse the entire quartz crystal in the quartz crystal etching solution to separate the tuning fork; in terms of volume concentration, it includes 10% - 30% hydrofluoric acid, 1% - 5% sulfuric acid, 0.1% - 0.3% surfactant, and the balance is water.

[0010] Specifically, the laser pulse used in the laser cutting in step S2 includes a pulse train, and the pulse train includes at least two sub-pulses.

[0011] Specifically, in the above step S2, infrared picosecond lasers are used for laser cutting.

[0012] Specifically, the pulse width of the above infrared picosecond laser is less than 10 ps, and the energy of the pulse train is greater than 500 μj.

[0013] Specifically, in the above step S2, the cutting speed of the laser beam focus during laser cutting is 50 - 200 mm / s, the point spacing is 4 - 6 μm, the Q frequency is 50 - 200 KHz, and the focus position is at the positive focus.

[0014] Specifically, in the above step S2, Bessel cutting heads are used for laser cutting.

[0015] Specifically, the cutting focal depth thickness of the above Bessel cutting head is H, where 1 mm ≤ H ≤ 3 mm.

[0016] Specifically, the above step S2 also includes detecting the cutting points of the quartz crystal.

[0017] Specifically, in the above step S3, the temperature at which the quartz crystal is immersed in the quartz crystal etching solution is 70 - 85 °C, and the immersion time is 4 - 6 h.

[0018] Specifically, the above cutting contour line has transverse cutting lines, longitudinal cutting lines, and waist-shaped cutting lines; among them, the transverse cutting lines are used to form the two sides of the tuning fork, the longitudinal cutting lines are used to form the two end faces of the tuning fork, and the waist-shaped cutting lines are used to form the tuning fork groove of the tuning fork.

[0019] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0020] The quartz crystal etching solution provided by the present invention is a specially formulated chemical etching solution with an optimized ratio. By adding a small amount of sulfuric acid and surfactant, the etching effect is enhanced, the etching uniformity is improved, the overall structure of the required tuning fork wafer can be precisely prepared, and the manufacturing accuracy and etching speed of the tuning fork wafer are improved. At the same time, the manufacturing cost is also taken into account. While obtaining a stable etching rate and the best etching surface, the cost for process replacement is saved.

[0021] The method for laser cutting a quartz crystal tuning fork provided by the present invention can not only simplify the processing procedures of the quartz crystal tuning fork, but also optimize the cutting quality, and is applicable to the large-scale manufacturing process, thus greatly improving the cutting efficiency and yield. This method selects a suitable laser and a laser cutting head through a cutting template, then loads a cutting drawing file through a control system and determines a cutting path. The laser and the laser cutting head perform an incomplete cutting on the template according to the cutting path, so that the focus of the laser beam forms a cutting and reforming layer within the quartz crystal. By controlling the energy of the laser pulse train and the number of sub-pulses included in the pulse train, as well as a customized Bessel cutting head, the cutting effect of the quartz crystal is ensured to ensure that the product can be smoothly separated after being corroded by a special liquid.

[0022] The following will further describe the present invention in detail with reference to the accompanying drawings. Description of the Drawings

[0023] Figure 1 is a schematic flow chart of the method for laser cutting a quartz crystal tuning fork provided in an embodiment of the present invention.

[0024] Figure 2 is a schematic diagram of the tuning fork cutting contour line provided in an embodiment of the present invention.

[0025] Figure 3 is a schematic diagram of the separated tuning fork structure.

[0026] Reference numerals: 1, quartz crystal; 2, tuning fork; 3, horizontal cutting line; 4, vertical cutting line; 5, waist-shaped cutting line. Detailed Embodiments

[0027] The following will clearly and completely describe the technical solutions in the present invention with reference to the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Although the representative embodiments of the present invention have been described in detail, those of ordinary skill in the technical field to which the present invention belongs will understand that various modifications and changes can be made to the present invention without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the embodiments, but should be defined by the appended claims and their equivalents.

[0028] The present invention provides a quartz crystal etching solution, which includes 10% - 30% hydrofluoric acid, 1% - 5% sulfuric acid, 0.1% - 0.3% surfactant, and the balance is water in terms of volume concentration. By adjusting the concentration of hydrofluoric acid, the etching rate and surface roughness are improved; a small amount of sulfuric acid can enhance the etching effect; the surfactant can improve the etching uniformity. The surfactant can be selected as sodium dodecyl sulfate.

[0029] The present invention also provides a method for laser cutting a quartz crystal tuning fork, including the following steps:

[0030] S1. Place the quartz crystal on the processing platform, use an industrial vision camera or other equipment to capture the mark points on the quartz crystal, use the visual computing unit to preset the cutting contour line of the tuning fork on the quartz crystal, load the cutting file through the control system and determine the cutting path.

[0031] The cutting contour line includes a transverse cutting line, a longitudinal cutting line and a waist-shaped cutting line; wherein the transverse cutting line is used to form two side edges of the tuning fork, the longitudinal cutting line is used to form two end faces of the tuning fork, and the waist-shaped cutting line is used to form a tuning fork groove of the tuning fork.

[0032] S2. Based on the preset cutting contour line, the quartz crystal is laser cut to form a cutting reformed layer, and plasma channels with equal spacing and penetrating the thickness of the quartz crystal are processed on the quartz crystal to form the contour of the tuning fork wafer.

[0033] In order to improve cutting efficiency and yield, the appropriate laser and laser cutting head are selected by cutting the sample, and the laser and laser cutting head perform incomplete cutting on the sample according to the cutting path.

[0034] The laser pulse of the laser includes a pulse train, and the pulse train includes at least two sub-pulses. The control system optimizes the accuracy of laser cutting and simplifies the processing process by controlling the laser pulse, thereby improving the cutting efficiency and yield.

[0035] The laser is preferably an infrared picosecond laser. The pulse width of the infrared picosecond laser is less than 10ps, and the pulse train energy is greater than 500uJ. The laser cutting head is preferably a Bessel cutting head.

[0036] During laser cutting, the laser pulse energy is controlled so that the laser beam passes through the Bessel cutting head and is focused inside the quartz crystal. The focus depth of the laser beam, i.e., the cutting focal depth thickness H of the Bessel cutting head, is generally in the range of 1mm≤H≤3mm. The laser cutting head and the laser beam focus move relative to the quartz crystal along the cutting contour line to form a cutting reformed layer inside the quartz crystal.

[0037] Furthermore, the cutting speed of the laser beam focal position platform is set to 50-200 mm / s, the point spacing is 4-6 um, the Q frequency is 50-200 KHz, and the focal position is positive focus.

[0038] The quartz crystal cutting points are inspected to ensure the accuracy and effect of the processing and cutting. The inspection instrument used is preferably a metallographic microscope with a measurement magnification greater than 500X.

[0039] S3. Immerse the whole quartz crystal in the quartz crystal etching solution to separate the tuning fork. In terms of volume concentration, it includes 10% - 30% hydrofluoric acid, 1% - 5% sulfuric acid, 0.1% - 0.3% surfactant, and the balance is water. The immersion temperature and etching time will also affect the etching effect. Preferably, it is 70 - 85 °C for 4 - 6 h.

[0040] This method controls the pulse train energy of the laser, the number of sub - pulses included in the pulse train, and the cutting head to ensure the cutting effect of the quartz crystal. The laser beam focus moves relative to the quartz crystal along a pre - set cutting path, forming a cutting and reforming layer in the quartz crystal to ensure that the product can be successfully separated after being corroded by the special liquid, optimizing the precision of laser cutting, simplifying the processing technological process, and thus improving the cutting efficiency and yield.

[0041] The following studies the effects of the quartz crystal etching solution of the present invention and the method of laser - cutting a quartz crystal tuning fork through specific examples.

[0042] Example 1:

[0043] This example provides a quartz crystal etching solution which, in terms of volume concentration, includes 20% hydrofluoric acid, 3% sulfuric acid, 0.2% sodium dodecyl sulfate, and the balance is water.

[0044] Based on this quartz crystal etching solution, referring to Figure 1 , this example also provides a method for laser - cutting a quartz crystal tuning fork, which includes the following steps:

[0045] S1. Place the quartz crystal on the processing platform, use an industrial vision camera to capture the Mark points on the quartz crystal, identify and calculate the cutting contour line of the tuning fork on the quartz crystal, load the cutting drawing file through the control system and determine the cutting path, as Figure 2 shown.

[0046] As can be seen from the figure, the surface of the quartz crystal has multiple repeating patterns of tuning fork wafers arranged in an array. The cutting contour line has horizontal cutting lines, vertical cutting lines, and waist - shaped cutting lines. Among them, the horizontal cutting lines are used to form the two sides of the tuning fork, the vertical cutting lines are used to form the two end faces of the tuning fork, and the waist - shaped cutting lines are used to form the tuning fork grooves of the tuning fork. Specifically, vertical cutting lines are inscribed on the outer sides of the first tuning fork wafer in any row and the last tuning fork wafer in a row. Horizontal cutting lines are inscribed on the upper and lower ends of this row of tuning fork wafers. The vertical cutting lines on both sides are connected to the horizontal cutting lines at the upper and lower ends, and the outer contours of the same tuning fork wafers are inscribed in sequence to finally form a closed laser - inscribed area. The two horizontal cutting lines of each row of tuning fork wafers coincide with the horizontal cutting lines of the tuning fork wafers in the adjacent rows above and below respectively, and the outermost vertical cutting lines of each row of tuning fork wafers are on the same straight line.

[0047] S2. Select an infrared picosecond laser and a Bessel cutting head through a cutting template. The pulse width of the infrared picosecond laser is less than 10 ps, and the energy of the pulse train is greater than 500 μJ. The laser pulse of the laser contains a pulse train, and the pulse train contains two sub-pulses.

[0048] Based on a preset cutting contour line, perform laser cutting on the quartz crystal. Control the laser pulse energy so that the laser beam passes through the Bessel cutting head and is focused inside the quartz crystal. The focusing depth of the laser beam focus, that is, the cutting focal depth thickness H of the Bessel cutting head, ranges from 1 mm ≤ H ≤ 3 mm. The laser cutting head and the laser beam focus move relative to the quartz crystal along the cutting contour line. The speed is set to 50 - 200 mm / s, the point spacing is 4 - 6 μm, the Q frequency is 50 - 200 KHz, and the focus position is the positive focus. A cutting and reforming layer is formed inside the quartz crystal, and equally spaced plasma channels penetrating the thickness of the quartz crystal are processed on the quartz crystal to form the contour of the tuning fork wafer.

[0049] Use a metallurgical microscope to detect the cutting points of the quartz crystal, and the magnification is greater than 500X to ensure the precision and effect of the processing and cutting.

[0050] S3. Immerse the whole quartz crystal in the quartz crystal etching solution and soak it at 80 °C for 5 h. After the etching is completed, separate out Figure 3 the shown tuning fork.

[0051] Example 2:

[0052] In this example, the wire cutting method is used as a control group to compare the differences in the machining accuracy of the size structures of the tuning fork wafers prepared by the method of laser cutting quartz crystal tuning forks provided in Example 1 of the present invention and the tuning fork wafers prepared by the traditional wire cutting processing method. The detection results of the size structures of the tuning forks (laser cutting tuning forks) prepared in Example 1 and the tuning forks (wire cutting tuning forks) prepared by the traditional method are shown in Table 1.

[0053] Table 1 Size structures of tuning forks prepared by different processing methods

[0054]

[0055] Making a horizontal comparison with the multiple size parameter values of the tuning fork products in Table 1, the tuning fork products prepared by the method of laser cutting quartz crystal tuning forks provided by the present invention have a smaller range of product size deviation, lower difference between products, and better consistency and stability compared with the tuning fork products prepared by the traditional wire cutting processing method.

[0056] Since the frequency distributions of the tuning fork products prepared by different processing methods in batches are different. Select 100 pieces each of the laser cutting tuning forks and the wire cutting tuning forks to measure the frequency point values, and the results are shown in Table 2.

[0057] Table 2 Tuning fork frequency distribution

[0058]

[0059]

[0060] It can be seen from the data in Table 2 that among the 100 tuning fork chips prepared by the method of the present invention, the frequency distribution of 97% of the tuning forks is concentrated in the same set, while the frequency distribution of the tuning fork chips prepared by traditional wire cutting processing is more dispersed and the frequency error is large, resulting in the need to adjust the frequency of the tuning fork chips in the later stage to meet the product frequency range standard requirements.

[0061] Embodiment 3:

[0062] This example studies the effects of different etching solutions, etching time and temperature on the tuning fork separation effect.

[0063] Experimental group: prepared by the method of laser cutting quartz crystal tuning fork provided in Example 1;

[0064] Control group 1: prepared by the method for laser cutting quartz crystal tuning fork provided in Example 1, except that the quartz crystal etching solution used in step S3 is a hydrofluoric acid aqueous solution with a volume concentration of 15%;

[0065] Control group 2: prepared by the method for laser cutting quartz crystal tuning fork provided in Example 1, the only difference being that the immersion temperature in step S3 is 75°C.

[0066] The separation rate, surface roughness, etc. of each group of tuning forks were tested at the same time, and the results are shown in Table 3.

[0067] Table 3 Etching effect

[0068] Average surface roughness Ra Separation rate Experimental group 0.006um 100％ Control group 1 0.006um 90％ Control group 2 0.008um 98％

[0069] It can be seen from Table 3 that under the same etching time, the tuning fork on the quartz crystal in the control group 1-2 cannot be completely separated, while the etching solution provided by the present invention can completely separate all the tuning forks after laser modification and cutting from the quartz crystal, with a fast etching speed, improved production efficiency, good etching uniformity, smooth surface and high precision.

[0070] In summary, the quartz crystal etching solution provided by the present invention is a specially formulated chemical etching solution with an optimized ratio. By adding a small amount of sulfuric acid and surfactant, the etching effect is enhanced, the etching uniformity is improved, the overall structure of the required tuning fork wafer can be precisely prepared, and the manufacturing accuracy and etching speed of the tuning fork wafer are increased. At the same time, the manufacturing cost is also taken into account. While obtaining a stable etching rate and the best etching surface, the cost for process replacement is saved. The method for laser cutting a quartz crystal tuning fork provided by the present invention can not only simplify the processing procedure of the quartz crystal tuning fork, but also optimize the cutting quality, and is applicable to large-scale manufacturing processes, thereby greatly improving the cutting efficiency and yield. This method selects a suitable laser and laser cutting head through a cutting template, then loads the cutting drawing file through a control system and determines the cutting path. The laser and laser cutting head perform an incomplete cut on the template according to the cutting path, so that the laser beam focus forms a cutting and reforming layer within the quartz crystal. By controlling the energy of the laser pulse train and the number of sub-pulses included in the pulse train, as well as a customized Bessel cutting head, the cutting effect of the quartz crystal is ensured to ensure that the product can be smoothly separated after being etched with a special liquid.

[0071] The above examples are only illustrative of the present invention and do not constitute a limitation on the protection scope of the present invention. Any design identical or similar to the present invention falls within the protection scope of the present invention.

Claims

1. A quartz crystal etching solution, characterized in that: Calculated by volume concentration, it includes 10% to 30% of hydrofluoric acid, 1% to 5% of sulfuric acid, 0.1% to 0.3% of surfactant, and the balance is water.

2. A method for laser cutting a quartz crystal tuning fork, characterized in that: The following steps are involved: S1. Preset the cutting contour of the tuning fork on the quartz crystal; S2, laser cutting the quartz crystal based on the cutting contour line to form a tuning fork contour; S3. Immerse the entire quartz crystal in a quartz crystal etching solution to separate the tuning fork; in terms of volume concentration, the quartz crystal etching solution includes 10% to 30% hydrofluoric acid, 1% to 5% sulfuric acid, 0.1 to 0.3% surfactant, and the remainder is water.

3. The method for laser cutting a quartz crystal tuning fork as claimed in claim 2, characterized in that: The laser pulse used for laser cutting in step S2 includes a pulse train, and the pulse train includes at least two sub-pulses.

4. The method for laser cutting a quartz crystal tuning fork as claimed in claim 2, characterized in that: In the step S2, the laser cutting adopts an infrared picosecond laser; the pulse width of the infrared picosecond laser is less than 10ps, and the pulse train energy is greater than 500μj.

5. The method for laser cutting a quartz crystal tuning fork as claimed in claim 2, characterized in that: The laser beam focus cutting speed of the laser cutting in step S2 is 50-200 mm / s, the point spacing is 4-6 μm, the Q frequency is 50-200 KHz, and the focus position is positive focus.

6. The method for laser cutting a quartz crystal tuning fork as claimed in claim 2, characterized in that: In step S2, the laser cutting adopts a Bessel cutting head.

7. The method for laser cutting a quartz crystal tuning fork as claimed in claim 6, characterized in that: The cutting focal depth thickness of the Bessel cutting head is H, 1mm≤H≤3mm.

8. The method for laser cutting a quartz crystal tuning fork as claimed in claim 2, characterized in that: The step S2 also includes detecting the cutting points of the quartz crystal.

9. The method for laser cutting a quartz crystal tuning fork as claimed in claim 2, characterized in that: In step S3, the quartz crystal is immersed in the quartz crystal etching solution at a temperature of 70 to 85° C. and a soaking time of 4 to 6 hours.

10. The method for laser cutting a quartz crystal tuning fork as claimed in claim 2, characterized in that: The cutting contour line comprises a transverse cutting line, a longitudinal cutting line and a waist-shaped cutting line; wherein the transverse The cutting line is used to form the two side edges of the tuning fork, and the longitudinal cutting line is used to form the two end faces of the tuning fork. The waist-shaped cut line is used to form the tuning fork groove of the tuning fork.

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