A crystal oscillator and its fabrication method

Abstract

This invention provides a crystal oscillator and its fabrication method. The crystal oscillator includes: a coated quartz wafer, an oscillating chip, and a base. The oscillating chip is bonded to the bottom of the inner cavity of the base with insulating adhesive and is bonded to electrodes located inside the oscillator base by gold wires. The coated quartz wafer is bonded to the electrodes using conductive adhesive in a four-point symmetrical bonding method. The crystal oscillator and its fabrication method provided by this invention, by using a four-point symmetrical bonding method to fix the coated quartz wafer to the electrodes, not only result in a simple, small, and highly stable product structure, but also effectively improve the shock resistance of the crystal oscillator, enabling it to be used normally under high overload conditions.

Description

Technical Field

[0001] This invention relates to the field of power electronics technology, and in particular to a crystal oscillator and its fabrication method. Background Technology

[0002] A crystal oscillator is a frequency control element. To date, small, shock-resistant surface-mount quartz crystal resonators have been widely used in high-overload electronic products. Due to the special nature of high-overload products, the impact reliability requirements for electronic components are extremely high.

[0003] Traditional crystal oscillator manufacturing has always used a four-point adhesive method, which uses two adhesive dots to achieve electrical connection between the quartz crystal and the electrodes. This makes it difficult for traditional surface-mount crystal resonators to meet the reliability requirements of strong vibration or impact. Ultimately, this may lead to abnormal situations such as crystal breakage or crystal failure during impact, resulting in electronic equipment failure and even irreversible serious consequences.

[0004] For example, Vectron's PX702 crystal oscillator can meet the shock resistance requirement of 3000g, but it is difficult to meet the target requirement of 36000g; GXL's GSV1 product can meet the shock resistance requirement of 20000g, and it uses two adhesive dots to fix the quartz crystal, but it is difficult to meet the target requirement of 36000g; there are currently no products in China that meet the shock resistance requirement of 36000g.

[0005] In view of this, there is an urgent need to improve the existing crystal oscillator assembly technology to provide a new type of crystal oscillator with shock resistance to meet the ever-evolving needs of high-overload electronic product R&D technology. Summary of the Invention

[0006] To address the problem of low shock resistance in existing crystal oscillators, this invention provides a crystal oscillator and its fabrication method.

[0007] The present invention provides a crystal oscillator, comprising: a coated quartz wafer, an oscillator chip, and a base; the oscillator chip is bonded to the bottom of the inner cavity of the base by insulating adhesive and bonded to an electrode located inside the oscillator base by gold wire; the coated quartz wafer is bonded to the electrode by conductive adhesive using a four-point symmetrical bonding method.

[0008] According to a crystal oscillator provided by the present invention, the coated quartz wafer is rectangular, and the adhesive dots between the coated quartz wafer and the electrode are located at the four corners of the rectangle.

[0009] According to a crystal oscillator provided by the present invention, the diameter of the adhesive dots is 150±15μm.

[0010] According to a crystal oscillator provided by the present invention, the side ratio of the coated quartz wafer is the ratio of its length to its width;

[0011] The length of the coated quartz wafer satisfies the following constraint:

[0012]

[0013] The width of the coated quartz wafer satisfies the following constraints:

[0014] |W1-W|>k2

[0015] W1 = 2540 × n / f;

[0016] Where L is the length of the coated quartz crystal, W is the width of the coated quartz crystal; L1 is the theoretical length when the even harmonics of the bending vibration frequency generated by the length are coupled with the main vibration, or when the odd harmonics generated by the surface shear vibration are coupled with the main vibration; W1 is the theoretical width when the surface shear vibration generated by the width is strongly coupled with the main vibration; k1 is the length difference value; k2 is the width difference value; n is the order of the overtone harmonics; and f is the frequency of the quartz crystal.

[0017] According to a crystal oscillator provided by the present invention, when the electrode material is silver, the coating return amount of the coated quartz wafer is any value between 0.4 and 1.5.

[0018] This invention also provides a method for fabricating a crystal oscillator, comprising: constructing impact-resistant models related to coated quartz wafers with different operating frequencies; conducting impact-resistant simulation tests on the impact-resistant models using Abaqus simulation software; adjusting the position and size of the adhesive dots, the edge ratio of the coated quartz wafer, the coating return amount of the coated quartz wafer, the size of the electrodes, and the cutting angle of the coated quartz wafer in each impact-resistant model according to the simulation test results, until the adjusted impact-resistant model can meet the experimental requirements of a preset impact pressure; obtaining the adjusted impact-resistant model; and generating the crystal oscillator based on the adjusted impact-resistant model.

[0019] According to the method for preparing a crystal oscillator provided by the present invention, the preset impact pressure is 36000g.

[0020] The crystal oscillator and its preparation method provided by the present invention fix the coated quartz wafer onto the electrode by means of four adhesive dots symmetrical bonding. The product has a simple structure, small size and strong stability, and effectively improves the impact resistance of the crystal oscillator. It can be used to solve the problem of normal use of crystal oscillators under high overload conditions. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a top view schematic diagram of the crystal oscillator provided by the present invention;

[0023] Figure 2 This is a side view schematic diagram of the crystal oscillator provided by the present invention;

[0024] Figure 3 This is a top view schematic diagram of a crystal oscillator in the prior art;

[0025] Figure 4 This is a schematic diagram showing the position of the adhesive dot shifted to the right during the simulation process;

[0026] Figure 5 This is a schematic diagram showing the position of the adhesive dot shifted to the left during the simulation.

[0027] Figure 6 This is a schematic diagram showing the situation where the adhesive dots are too large during the simulation process;

[0028] Figure 7 This is a schematic diagram showing the size of the adhesive dots during the simulation process.

[0029] Figure 8 This is a schematic flowchart of a method for preparing a crystal oscillator provided by the present invention;

[0030] The attached figures are labeled as follows:

[0031] 1: Base; 2: Coated quartz wafer; 3: Silver electrode;

[0032] 4: Elongated electrode; 5: First electrode; 6: Second electrode;

[0033] 7: First adhesive point; 8: Second adhesive point; 9: Third adhesive point;

[0034] 10: Fourth adhesive point; Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0036] It should be noted that in the description of the embodiments of the present invention, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, article, or apparatus that includes said element. The terms "upper," "lower," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly, for example, as a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; or a connection within two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0037] The following is combined with Figures 1-8 The crystal oscillator provided in the embodiments of the present invention is described.

[0038] Figure 1 This is a top view schematic diagram of the crystal oscillator provided by the present invention. Figure 2 This is a side view schematic diagram of the crystal oscillator provided by the present invention, as shown below. Figure 1 and Figure 2 As shown, including but not limited to: a coated quartz wafer 2, an oscillating chip, and a base 1; the oscillating chip is bonded to the bottom of the inner cavity of the base 1 with insulating adhesive and bonded to the electrodes located inside the base 1 with gold wire; the coated quartz wafer 2 is bonded to the electrodes with conductive adhesive using a four-prong symmetrical bonding method.

[0039] Figure 3This is a top view schematic diagram of a crystal oscillator in the prior art, which uses a two-dot adhesive bonding method to electrically connect and fix the coated quartz crystal wafer to the electrodes. Because the adhesive bonding is only formed at one end of the coated quartz crystal wafer, the end of the coated quartz crystal wafer is basically in a suspended state.

[0040] Unlike existing crystal oscillators, the crystal oscillator provided by this invention mainly consists of a coated quartz wafer 2, an oscillation chip, a base 1, and an outer cover. The oscillation chip is bonded to the bottom of the inner cavity of the base 1 with insulating adhesive and is electrically connected to the electrodes inside the base via gold wires (diameter Ф0.025mm). The coated quartz wafer 2 is bonded to the corresponding electrodes inside the base with conductive adhesive.

[0041] The oscillator housing is welded to the base sealing ring by parallel sealing welding to form a sealed cavity, and the oscillator housing is connected to the ground.

[0042] As an optional embodiment, the crystal oscillator provided by the present invention, constructed by symmetrical bonding of four adhesive dots, has an elongated electrode 4 on one side of the working surface of the base 1, and a first electrode 5 and a second electrode 6 on the other side. The silver electrode 3 on the coated quartz wafer 2 is electrically bonded to the second electrode 6 via adhesive dots 8, and to the first electrode 5 via adhesive dots 7. The coated quartz wafer 2 is also electrically bonded to the elongated electrode 4 via adhesive dots 9 and 10.

[0043] It should be noted that each adhesive dot can consist of a top adhesive and a base adhesive, that is, the top adhesive is placed above the electrical bonding point and the base adhesive is placed below the electrical bonding point; or, the base adhesive is placed above the electrical bonding point and the top adhesive is placed below the electrical bonding point.

[0044] To address the improved impact resistance of the crystal oscillator provided by this invention, the present invention utilizes Abaqus simulation software to compare the stress and deformation simulation results of impact resistance models using two-, three-, and four-adhesive-point bonding.

[0045] Table 1 Comparison of Structural Analysis Data

[0046] structure Two glue dots Three glue dots Four glue points Two glue dots versus four glue dots Maximum stress 0.34N 0.058N 0.0075N 45.3 times Maximum displacement 216nm 18.7nm 6.34nm 34.1 times

[0047] As shown in Table 1, the maximum stress of the crystal oscillator using two adhesive dots is 0.34 N, and the maximum displacement is 216 nm. Crystal oscillators using three or four adhesive dots show significant reductions in stress and maximum displacement. In particular, the crystal oscillator using four adhesive dots exhibits a maximum stress of 0.0075 N, which is 1 / 45.3 of that of the two-dot structure, and a maximum displacement of 6.34 nm, which is 1 / 34.1 of that of the two-dot structure.

[0048] Furthermore, because the crystal oscillator with two adhesive points uses a cantilever beam design, the quartz crystal undergoes a large displacement during impact testing. In contrast, the crystal oscillator with four adhesive points can distribute the stress evenly, resulting in significantly improved impact resistance compared to the crystal oscillator with two adhesive points. This also aligns with the testing process where the crystal oscillator with four adhesive points could withstand an impact greater than 20,000g, while the crystal oscillator with two adhesive points could not withstand such an impact, leading to breakage.

[0049] Based on the simulation results above, it can be seen that the crystal oscillator provided by the present invention fixes the coated quartz wafer onto the electrode by using a four-prong symmetrical bonding method. This not only results in a simple, small, and highly stable product structure, but also effectively improves the shock resistance of the crystal oscillator, and can be used to solve the problem of normal use of the crystal oscillator under high overload conditions.

[0050] Based on the above embodiments, as an optional embodiment, the coated quartz wafer is rectangular, and the adhesive dots between the coated quartz wafer and the electrode are located at the four corners of the rectangle.

[0051] Impact refers to the physical phenomenon where a system is subjected to a sudden, instantaneous excitation within a very short time, causing a sudden change in its displacement, velocity, or acceleration. Impact has the following characteristics: the impact duration is extremely short, with energy release, conversion, and transfer completed abruptly within a very short time; the impact excitation is not periodic, and the motion generated by the product is instantaneous; under impact, the product's motion response is related to the duration of the impact. The failure phenomenon of crystal oscillators under impact is generally the shattering of the coated quartz crystal wafer, while the ceramic substrate and adhesive dots remain intact. Therefore, the mounting and fixing method of the coated quartz crystal wafer 2 is a core factor affecting the structure of the crystal oscillator.

[0052] According to the first strength theory (proposed by Galileo), maximum stress is the primary factor causing material failure; when the maximum stress reaches a limit value related to the material's properties, the material fractures. According to the second strength theory (proposed by Mario), stress is the primary factor causing material failure at maximum elongation strain; when the maximum elongation strain reaches a limit value related to the material's properties, the material fractures. Therefore, structural design processes must avoid excessive deformation and displacement, while also preventing stress concentration.

[0053] The structural design of a crystal oscillator directly determines its reliability and performance indicators. Considering the impact resistance requirements (e.g., 36000g and above), compared to existing non-impact oscillator products, the crystal oscillator provided by this invention employs a structure with added adhesive dots. This design, compared to using two adhesive dots to bond the coated quartz wafer, can withstand higher impact levels and provides good buffering for the wafer during high-impact tests, ensuring it does not shatter. However, to reasonably meet the 36000g impact resistance test requirements through the crystal oscillator's structural design, repeated simulation experiments and verifications of the entire crystal oscillator's structure are necessary.

[0054] It should be noted that since changes in the structural design of the crystal oscillator can cause changes in the electrical parameters of the product, this invention also conducted in-depth research on the structure of the coated quartz wafer, the structure of the electrodes, and the connection methods between them.

[0055] For example, the structural change of adding adhesive dots affects the electrical parameters of the coated quartz crystal wafer. To meet the accuracy requirement of ±45ppm within the range of -55℃ to 105℃, it is necessary to rationally design the edge ratio of the coated quartz crystal wafer, the coating return amount, and the electrode dimensions to ensure the stable output frequency of the crystal oscillator and prevent parasitic effects caused by vibration coupling, which could lead to frequency jumps. Simultaneously, the cutting angle of the coated quartz crystal wafer must also be rationally designed to improve the frequency temperature stability index. Therefore, the specialized process research on crystal oscillator parameters is a key technology that directly affects the technical specifications of impact-resistant products.

[0056] Specifically, the crystal oscillator provided by this invention is based on Abaqus simulation software and repeatedly simulates an impact model. By using the simulation software, the scientific nature of the dispensing structure design is ensured, and the rationality of the dispensing structure is verified through impact tests. Finally, the optimal dispensing position for different coated quartz crystal wafer frequencies is determined.

[0057] Figure 4 This is a schematic diagram showing the position of the adhesive dot shifted to the right during the simulation. Figure 5 This is a schematic diagram showing the position of the adhesive dot shifted to the left during the simulation, as shown below. Figure 4 as well as Figure 5 As shown, with Figure 1 Compared to the crystal oscillator shown, when the adhesive dot is positioned to the right, the dot connects to the edge, posing a significant manufacturing risk. When the adhesive dot is positioned to the left, the short step of the base does not provide sufficient distance to support the coated quartz wafer, making the fabrication process impossible.

[0058] In view of this, such as Figure 1As shown, in the crystal oscillator provided by this invention, when the coated quartz wafer is rectangular, the positions of the adhesive dots are specifically defined as follows: the first adhesive dot 7 is located at the upper left corner of the coated quartz wafer 2, the second adhesive dot 8 is located at the lower left corner of the coated quartz wafer 2, the third adhesive dot 9 is located at the upper right corner of the coated quartz wafer 2, and the fourth adhesive dot 10 is located at the lower right corner of the coated quartz wafer 2. All are connected with the wafer corner of the coated quartz wafer 2 as the center. Both the third adhesive dot 9 and the fourth adhesive dot 10 are in contact with the end of the silver electrode 3. The elongated electrode 4 is parallel to the first electrode 5 and the second electrode 6, forming two opposite sides of a rectangle.

[0059] Optionally, the coated quartz wafer 2 is made by grinding and coating quartz crystals, and its surface roughness is less than or equal to 20 nm. Both sides of the coated quartz wafer 2 have a coating, which can be one of the following materials: gold, silver, aluminum, chromium, etc., and the coating pattern is as follows: Figure 1 As shown, the central portion of the front and back images are identical, with rectangular first electrode 5 and second electrode 6 extending from the left edge and connected to the base. The first electrode 5 and second electrode 6 are bonded to the base electrodes using conductive adhesive. The third adhesive point is not connected to the silver electrode 3 of the coated quartz wafer.

[0060] The base is made entirely of insulating material. If ceramic material is used, a top cover is encapsulated on the surface of the base. The top cover is made of metal material, such as iron plated with nickel, iron-cobalt-nickel, or iron-cobalt-nickel plated with nickel.

[0061] As shown in Table 2, impact tests were conducted on quartz wafers at 10M, 40M, 60M, and 100M according to method 2002.1 of GJB 548B-2005 to verify their reliability. The peak acceleration under the test conditions was 36,000g, and no breakage was observed in the 16 tested products.

[0062] Table 2 Impact Resistance Test Results

[0063]

[0064] It should be noted that during the actual research and development process, this invention also underwent multi-adhesive-dot (the number of adhesive dots is greater than 4) analysis and verification. The specific results are as follows:

[0065] If adhesive dots are added to the crystal oscillator provided by this invention, that is, adhesive dots need to be added at positions other than the four corners of the coated quartz crystal wafer, process experiments show that adding adhesive dots at other positions will increase the likelihood of product oscillation failure and process instability, affecting the yield rate, and there is no space to apply adhesive. At the same time, if the stress of the crystal oscillator is too high, it will cause the electrical parameters to deteriorate. Therefore, too many adhesive dots will affect the vibration of the quartz crystal itself, resulting in unqualified electrical parameters.

[0066] The crystal oscillator provided by this invention has a simple and small structure. Using this crystal resonator can provide a clock input for the chip with strong stability. Due to the addition of an impact-resistant four-point symmetrical bonding structure and a surface roughness design, the product can effectively prevent product damage caused by high overload.

[0067] Based on the above embodiments, as an optional embodiment, the diameter of the adhesive dots is 150±15μm.

[0068] Figure 6 This is a schematic diagram showing when the adhesive dots are too large during the simulation. Figure 7 This is a schematic diagram showing the size of the adhesive dots during the simulation, such as... Figure 6 as well as Figure 7 As shown, with Figure 1 Compared to the crystal oscillator shown, if the adhesive dots are too large, they are prone to connecting with the edge of the base, causing significant process risks; if the adhesive dots are too small, the bonding strength will be poor.

[0069] In view of this, the crystal oscillator provided by the present invention, through experiments with different adhesive dot sizes, finally determined that the diameter of each adhesive dot on the coated quartz wafer is 150±15μm.

[0070] Based on the above embodiments, as an optional embodiment, the side ratio of the coated quartz wafer is the ratio of its length to its width;

[0071] The length of the coated quartz wafer satisfies the following constraint:

[0072]

[0073] The width of the coated quartz wafer satisfies the following constraints:

[0074] |W1-W|>k2

[0075] W1 = 2540 × n / f;

[0076] Where L is the length of the coated quartz crystal, W is the width of the coated quartz crystal; L1 is the theoretical length when the even harmonics of the bending vibration frequency generated by the length are coupled with the main vibration, or when the odd harmonics generated by the surface shear vibration are coupled with the main vibration; W1 is the theoretical width when the surface shear vibration generated by the width is strongly coupled with the main vibration; k1 is the length difference value; k2 is the width difference value; n is the order of the overtone harmonics; and f is the frequency of the quartz crystal.

[0077] This invention employs a four-dot symmetrical bonding method to construct a crystal oscillator. To meet the accuracy requirement of ±45ppm within the range of -55℃ to 105℃, the edge ratio and coating return amount of the coated quartz wafer must be rationally designed to ensure the frequency stability of the crystal oscillator and prevent parasitic effects caused by vibration coupling, which could lead to frequency jumps. This improves the frequency temperature stability index, as shown in Table 3 (key data is highlighted in bold):

[0078] Table 3 Oscillator Configuration File Parameters

[0079] ℃ Frppm Ima ℃ Frppm Ima ℃ Frppm Ima ℃ Frppm Ima ℃ Frppm Ima 25.01 35.59 4.29 25.00 32.47 4.19 25.01 24.78 4.39 25.00 26.75 4.29 25.01 29.35 3.99 -55.51 -67.93 4.02 -55.49 -68.35 4.12 -55.51 -73.30 4.22 -55.51 -61.28 4.33 -55.50 -23.5K 4.22 -40.49 -4.24 4.04 -40.49 -58.82 4.05 -40.49 -25.57K 4.04 -40.49 -3.28 4.24 -40.50 -1.21 4.04 -30.00 21.63 3.93 -30.00 18.61 3.92 -30.00 9.67 4.22 -30.00 19.03 3.93 -30.00 19.86 3.99 -20.00 38.37 4.16 -20.00 34.73 4.06 -20.00 29.84 4.01 -20.00 32.44 4.16 -20.00 35.04 4.16 -10.00 48.48 3.89 -10.00 44.64 3.99 -10.00 37.46 3.89 -10.00 41.62 3.99 -10.00 44.01 3.99 0.00 53.24 3.09 0.00 50.44 3.49 0.00 41.81 3.19 0.00 45.97 3.09 0.00 47.95 3.99 10.00 56.05 3.08 10.00 52.41 3.08 10.00 43.68 3.08 10.00 46.59 3.08 10.00 49.40 3.38 20.01 55.74 3.24 20.01 51.79 3.14 20.01 42.33 3.14 20.01 45.24 3.44 20.01 48.15 3.34 29.98 53.21 3.16 29.98 50.55 3.26 29.98 41.19 3.16 29.98 42.75 3.16 29.98 45.25 3.16 39.99 51.98 3.27 39.99 47.83 3.07 39.99 38.26 3.27 39.99 38.99 3.27 39.99 42.11 3.27 49.99 48.66 3.67 49.99 44.60 3.67 49.99 35.14 3.17 49.99 35.77 3.67 49.99 38.99 3.37 59.99 47.21 3.78 59.99 42.45 3.38 59.99 32.14 3.18 59.99 33.07 3.38 59.99 37.44 3.78 70.00 48.04 3.99 70.00 43.25 3.94 70.00 31.09 3.99 70.00 32.13 3.49 70.00 36.39 3.99 80.00 50.98 4.01 80.00 45.67 4.11 80.00 32.68 4.11 80.00 33.72 4.21 80.00 38.30 4.31 85.01 53.23 4.02 84.99 47.76 4.02 85.01 35.08 4.02 85.00 38.02 4.02 85.00 40.90 4.12 95.00 61.78 4.09 95.00 55.55 4.19 95.00 42.35 4.19 95.00 42.87 4.02 95.00 48.38 4.29 105.49 74.56 4.15 105.48 68.94 4.2 105.49 55.84 4.25 105.50 55.43 4.12 105.49 61.46 4.25

[0080] On the one hand, changes in the mounting method of the coated quartz crystal wafer can lead to changes in the stress mode of the crystal oscillator. This manifests as a greater likelihood of coupling between the master mode (thickness shear vibration) and parasitic modes (bending vibration, surface shear vibration), resulting in abnormal abrupt changes in the master frequency. On the other hand, changes in the mounting method of the coated quartz crystal wafer, due to the difference in thermal expansion coefficients between the adhesive points and the coated quartz crystal wafer, can cause changes in the thermal stress of the crystal oscillator due to temperature variations. According to the "force-frequency effect," this may lead to changes in the frequency-temperature characteristics of the crystal oscillator.

[0081] Taking the above factors into consideration, the crystal oscillator provided by the present invention is designed for the edge ratio of the coated quartz wafer.

[0082] Theoretically speaking, if the length of a rectangular coated quartz wafer is not properly selected, the even harmonics of the bending vibration frequency generated along its length direction will couple with the main oscillator, or the odd harmonics generated by the surface shear vibration will couple with the main oscillator. When coupling occurs, parasitic effects will also be generated.

[0083] The thickness t of the coated quartz wafer is given by the formula t = nK f / f determines the order of the overtone harmonics, where n is the order of the overtone harmonics, and K f ≈1670kHz·mm, where f is the frequency of the quartz crystal. Therefore, the parasitic properties can be improved by rationally designing the length L and width W of the coated quartz crystal.

[0084] The length L is chosen primarily to avoid coupling with the bending vibration of the X' plane. Using f = 1338·n / L1, therefore L1 = 1338·n / f. Only with even harmonics, the bending vibration strongly couples to the main vibration. Therefore, to avoid strong coupling between the bending vibration and the main vibration, the length of the coated quartz wafer should be selected to avoid the dimension calculated by the above formula, and the difference should be greater than 0.02 mm.

[0085] The selection of width W is primarily to avoid surface shear coupling with the Z' plane. Using f = 2540·n / W1, we get W1 = 2540·n / f. Only with odd harmonics does surface shear vibration strongly couple to the main vibration. Therefore, to avoid strong coupling between surface shear vibration and the main vibration, the width of the rectangular plate should avoid the dimension calculated by the above formula, and the difference should be greater than 0.02 mm. This ensures that the side ratio design of the coated quartz wafer meets the requirement of suppressing parasitic vibrations.

[0086] Based on the above embodiments, as an optional embodiment, when the electrode material is silver, the coating return amount of the coated quartz wafer is any value between 0.4 and 1.5.

[0087] The etching frequency is the frequency of the coated quartz wafer before coating, and it is generally higher than the nominal frequency. By depositing an electrode film on the surface of the wafer, the frequency of the coated quartz wafer can be brought back to near its nominal frequency.

[0088] Corrosion frequency = nominal frequency + K × nominal frequency squared;

[0089] Where K is the coating return amount, the nominal frequency is in kHz, and the nominal frequency squared is in MHz.

[0090] There is no strict theoretical basis for the coating return amount. However, increasing the electrode film thickness will accelerate crystal aging and may generate or amplify parasitic degradation. The coating return amount determines the electrode film thickness and also affects the parasitic parameters of the crystal. Often, an appropriate value is found based on empirical values ​​and verified through experiments. This invention demonstrates through repeated experiments that when silver is used as the electrode material, the coating return amount should be maintained between 0.4 and 1.5. This ensures that the electrode film thickness has minimal impact on the equivalent resistance of the crystal oscillator, while maximizing the approximation of the corrosion frequency to the nominal frequency.

[0091] Based on the above-mentioned internal design requirements of the crystal oscillator provided by this invention, and according to the existing coated quartz wafer design library, parasitics are suppressed by comprehensively designing the edge ratio size and coating return amount of the coated quartz wafer. Specific experimental schemes are shown in Tables 4-6:

[0092] Table 4. Corrosion Frequency Test Scheme for Coated Quartz Wafers

[0093]

[0094] Table 5. Specifications and Test Procedures for Coated Quartz Wafers

[0095] frequency size Corrosion frequency Coating area 10M 3.5*1.8 20350-20450 1.8*1.4 40M 3.5*1.875 40900-40980 1.5*1.0 60M 3.5*1.8 20250-20340 1.5*1.0 100M 3.5*1.8 34000-34120 1.8*1.4

[0096] Table 6. Side-to-side test scheme for coated quartz wafers

[0097] Serial Number Product frequency Quartz wafer edge ratio design 1 10 3.5mm*1.8mm, 3.495*1.795mm 2 20 3.5mm*1.8mm, 3.495*1.795mm 3 40 3.5mm*1.875mm, 3.495*1.795mm 4 60 3.5mm*1.8mm, 3.495*1.795mm 5 100 3.5mm*1.8mm, 3.495*1.795mm

[0098] The crystal oscillator fabrication experiments were conducted according to the test contents shown in Tables 5 and 6 above, and the results of each experiment are shown in Tables 7 and 8. Finally, the qualified test results were archived in a file to provide a basis for subsequent mass production.

[0099] Table 7. Results of corrosion frequency tests on coated quartz wafers.

[0100]

[0101]

[0102] Table 8. Side ratio test results of coated quartz wafers

[0103]

[0104] The simulation and impact tests verified the design scheme of the crystal oscillator with a four-point symmetrical bonding structure and clarified the position of the adhesive points. The size of the adhesive points was determined through process exploration. Through the test and verification of the electrical parameters of the crystal oscillator, the parameter design of the coated quartz wafer under the new structure was finally determined, and the electrical parameters of the entire crystal were verified, which effectively improved the impact resistance of the crystal oscillator.

[0105] Figure 8 This is a schematic flowchart of a method for preparing a crystal oscillator provided by the present invention, as shown below. Figure 8 As shown, including but not limited to the following steps:

[0106] Step S1: Construct impact resistance models for coated quartz wafers with different operating frequencies;

[0107] Step S2: Conduct impact resistance simulation tests on the impact-resistant models using Abaqus simulation software;

[0108] Step S3: Based on the simulation test results, adjust the position and size of the adhesive dots, the edge ratio of the coated quartz wafer, the coating return amount of the coated quartz wafer, the size of the electrode, and the cutting angle of the coated quartz wafer in each of the impact resistance models until the adjusted impact resistance models can meet the experimental requirements of the preset impact pressure.

[0109] Step S4: Obtain the adjusted anti-impact model;

[0110] Step S5: Generate the crystal oscillator according to the adjusted anti-impact model.

[0111] Optionally, the preset impact pressure is 36000g.

[0112] The research and development route of the crystal oscillator of this invention mainly includes three stages: structural simulation, crystal oscillator fabrication, and experimental verification.

[0113] First, based on the content described in the above embodiments, each impact resistance model is determined, including the position and size of the adhesive dots, the edge ratio of the coated quartz wafer, the coating return amount of the coated quartz wafer, the size of the electrode, and the cutting angle of the coated quartz wafer, etc., to ensure that the crystal oscillator obtained by structural simulation can meet the impact resistance requirements of a maximum impact of 36000g and above.

[0114] Then, by debugging the dispensing machine program and developing a template, the design scheme of symmetrical bonding of four adhesive dots was verified through process experiments.

[0115] It should be noted that the method for preparing a crystal oscillator provided in this embodiment of the invention can be used to prepare the crystal oscillator described in any of the above embodiments, and will not be elaborated on in this embodiment.

[0116] The method for preparing a crystal oscillator provided by the present invention fixes the coated quartz wafer onto the electrode by means of symmetrical bonding with four adhesive dots. This not only results in a simple, small, and highly stable product structure, but also effectively improves the shock resistance of the crystal oscillator, and can be used to solve the problem of normal use of the crystal oscillator under high overload conditions.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A crystal oscillator, characterized in that, include: Coated quartz wafers, oscillating chips, and substrates; The oscillating chip is bonded to the bottom of the inner cavity of the base with insulating adhesive and is bonded to the electrodes located inside the base with gold wire to form an electrical connection. The coated quartz wafer is bonded to the electrode using conductive adhesive and a four-point symmetrical bonding method. The side ratio of the coated quartz wafer is the ratio of its length to its width; The length of the coated quartz wafer satisfies the following constraint: The width of the coated quartz wafer satisfies the following constraints: |W1-W|>k2 W1 = 2540 × n / f; Where L is the length of the coated quartz crystal, W is the width of the coated quartz crystal; L1 is the theoretical length when the even harmonics of the bending vibration frequency generated by the length are coupled with the main vibration, or when the odd harmonics generated by the surface shear vibration are coupled with the main vibration; W1 is the theoretical width when the surface shear vibration generated by the width is strongly coupled with the main vibration; k1 is the length difference value; k2 is the width difference value; n is the order of the overtone harmonics; and f is the frequency of the quartz crystal.

2. The crystal oscillator according to claim 1, characterized in that, The coated quartz wafer is rectangular, and the adhesive dots between the coated quartz wafer and the electrode are located at the four corners of the rectangle.

3. The crystal oscillator according to claim 2, characterized in that, The diameter of the adhesive dots is 150±15μm.

4. The crystal oscillator according to claim 1, characterized in that, When the electrode material is silver, the coating return amount of the coated quartz wafer is any value between 0.4 and 1.

5.

5. A method for preparing a crystal oscillator as described in any one of claims 1-4, comprising: Construct impact resistance models for coated quartz wafers with different operating frequencies; Impact resistance simulation tests were conducted on the aforementioned impact resistance models using Abaqus simulation software. Based on the simulation test results, the position and size of the adhesive dots, the edge ratio of the coated quartz wafer, the coating return amount of the coated quartz wafer, the size of the electrode, and the cutting angle of the coated quartz wafer in each of the impact resistance models were adjusted until the adjusted impact resistance models could meet the experimental requirements of the preset impact pressure. Obtain the adjusted impact resistance model; The crystal oscillator is generated based on the adjusted anti-impact model.

6. The method for preparing a crystal oscillator according to claim 5, characterized in that, The preset impact pressure peak acceleration is 36000g.

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