High-stability tuning fork crystal resonator

Abstract

The utility model discloses a kind of high-stability tuning fork crystal resonator, it is related to crystal resonator technical field, including ceramic pedestal, inner cavity is equipped in the ceramic pedestal, the inner cavity is equipped with wafer and the pedestal PAD of symmetrical arrangement, the middle of the pedestal PAD is equipped with boss, the both sides of the boss are equipped with conductive glue point, the carrying area of the wafer is connected with the boss and the conductive glue point, the conductive glue point is flattened after being pressed by the carrying area, and the height of the boss is same, the carrying area is extended and is connected with the frequency adjustment area located in middle part. The technical problem to be solved by the utility model lies in providing a kind of high-stability tuning fork crystal resonator, by the structure size design of pedestal and wafer, using four-point glue mode, guarantee the parallelism after wafer carrying, under the premise of not increasing impedance, improve the reliability and stability of crystal.

Description

Technical Field

[0001] This utility model relates to the field of crystal resonator technology, specifically to a high-stability tuning fork crystal resonator. Background Technology

[0002] Tuning fork crystals, due to their miniaturization, low power consumption, and excellent frequency stability, are widely used in many key fields, including watches (especially watch movements), smartphones, tablets, microcomputers, calculators, home appliance automatic control systems, and industrial automation control equipment. Currently, the downstream application market for tuning fork crystals in China is showing strong growth, with the continuously expanding application scenarios effectively driving market demand. At the same time, to adapt to the increasingly thinner and smarter trends in end products, tuning fork crystal technology itself is constantly evolving, showing a significant trend towards miniaturization and high stability. However, in the domestic tuning fork crystal manufacturing sector, core manufacturing processes have not yet reached full maturity, resulting in a certain gap between domestically produced products and international advanced levels in key frequency stability indicators. Utility Model Content

[0003] Technical problem to be solved by the utility model

[0004] The technical problem to be solved by this utility model is to provide a high-stability tuning fork crystal resonator. Through the structural size design of the base and the crystal, and by using a four-point adhesive method, the parallelism of the crystal after mounting is ensured, thereby improving the reliability and stability of the crystal without increasing the impedance.

[0005] Technical solution

[0006] To solve the above problems, the technical solution provided by this utility model is as follows:

[0007] A high-stability tuning fork crystal resonator includes a ceramic substrate with an inner cavity. The inner cavity contains a wafer and symmetrically arranged base PADs. A boss is provided in the middle of the base PADs, and conductive adhesive dots are provided on both sides of the boss. The mounting area of ​​the wafer is connected to the boss and the conductive adhesive dots. The conductive adhesive dots are flattened by the mounting area and have the same height as the boss. A frequency adjustment area located in the middle is extended from the mounting area.

[0008] The ceramic base and inner cavity provide the basic structure for support, protection, and electrical connection. Symmetrically arranged base PADs serve for electrical connection and mechanical support. The central boss of the base PAD acts as the physical reference plane / height positioning point for wafer mounting. It defines the theoretical mounting position of the wafer in the Z-axis direction (height direction). This ensures the wafer has a precise and stable mounting plane, avoiding direct contact with uneven surfaces or surfaces entirely reliant on adhesive. Conductive adhesive dots on both sides of the boss provide electrical connection (connecting the wafer electrodes to the base PAD) and partial mechanical fixation. Symmetrically arranged on both sides, they form four support points (one on each side of the boss on each PAD). The wafer mounting area connects to the boss and conductive adhesive dots, and the wafer contacts the base structure through its mounting area.

[0009] Optionally, the inner cavity has a length of 1.5~1.8mm and a width of 0.6~1.0mm, the base PAD is close to the edge of the inner cavity, the base PAD has a length of 0.40~0.46mm and a width of 0.19~0.23mm.

[0010] Miniaturization: The internal cavity size directly targets the current smallest packaging standard; High stability: Through PAD edge layout, precise width tolerance, and space margin reservation, a hardware foundation is provided for four-point adhesive process and vibration reliability; Low impedance: Short electrode path suppresses parasitic effects; Dimensional accuracy makes up for the gap in process maturity and narrows the gap in frequency stability indicators with international standards.

[0011] Optionally, the width of the boss is 0.02~0.04mm, and the height of the boss is 0.01~0.02mm.

[0012] Improved frequency stability and guaranteed stress symmetry; enhanced resistance to mechanical shock, with the "limiter" function of the micro-protrusions.

[0013] Optionally, the length of the crystal is 1.39~1.43mm and the width of the crystal is 0.54~0.58mm.

[0014] The length direction of the crystal ensures the free space for vibration; the width direction provides the rigid basis for the four-point adhesive process.

[0015] Optionally, the length of the mounting area is 0.42~0.48mm, and the width of the mounting area is 0.07~0.11mm.

[0016] The narrow bridge mounting area features a vibration isolation design, forming a "narrow bridge" structure (only 13%~20% the width of the crystal body). This isolates the transmission of vibration energy from the tuning fork arm to the base, reducing Q-value loss. It spans the base PAD (0.40~0.46mm in length), achieving full coverage of the boss and double adhesive points, increasing the bonding area by 30%.

[0017] Optionally, the edges of the mounting area are provided with a chamfered structure.

[0018] A reduced stress concentration factor helps improve the structural strength of the mounting area.

[0019] Optionally, the conductive adhesive dots are pressed down by the mounting area to a value greater than 1 / 2 of the conductive adhesive dots.

[0020] The conductive adhesive dots are pressed down to more than 1 / 2 of their original size by the mounting area (e.g., compressed from 0.04mm to >0.02mm), resulting in better mechanical stability and zero-tilt installation; optimized electrical performance and precise impedance control; and low cost and high yield.

[0021] Optionally, the height of the conductive adhesive dots is 0.05~0.07mm.

[0022] It is highly compatible with the boss.

[0023] Beneficial effects

[0024] Compared with the prior art, the technical solution provided by this utility model has the following advantages:

[0025] The technical solution provided by this utility model, through a base structure (PAD with bosses) and a precise fixing process (flattening four conductive adhesive dots to the same height as the bosses), forcibly and repeatably ensures extremely high parallelism of the chip mounting on the base. This function directly solves the key mechanical factors affecting the performance of tuning fork crystal oscillators (especially frequency stability), significantly improving frequency stability: reducing frequency drift caused by mounting tilt and uneven stress, narrowing the gap with international advanced levels. It ensures low impedance: through rigid boss support and precise adhesive control, it avoids introducing additional losses and impedance increases caused by stress. It enhances reliability: providing a stable, low-stress mounting, resisting environmental stress and reducing the risk of failure. It potentially improves process maturity: providing structured assembly standards and methods, which is conducive to improving production consistency and yield. Attached Figure Description

[0026] Figure 1 A schematic diagram of a high-stability tuning fork crystal resonator proposed for an embodiment of this utility model;

[0027] Figure 2 This is one embodiment of a high-stability tuning fork crystal resonator proposed in this utility model;

[0028] Figure 3 This is a second embodiment of a highly stable tuning fork crystal resonator proposed for the purposes of this utility model;

[0029] Figure 4A schematic diagram of a high-stability tuning fork crystal resonator proposed for an embodiment of this utility model;

[0030] 1. Chip; 2. First conductive adhesive dot; 3. Second conductive adhesive dot; 4. Boss; 5. First frequency adjustment area; 6. Second frequency adjustment area; 7. Base PAD; 8. Mounting area. Detailed Implementation

[0031] To further understand the content of this utility model, a detailed description of this utility model will be provided in conjunction with the accompanying drawings and embodiments.

[0032] Example 1

[0033] Combined with appendix Figure 1-4 A high-stability tuning fork crystal resonator includes a ceramic base, an inner cavity within the ceramic base, a crystal wafer and symmetrically arranged base PADs within the inner cavity, a boss in the middle of the base PADs, and conductive adhesive dots on both sides of the boss, namely a first conductive adhesive dot and a second conductive adhesive dot, respectively.

[0034] The chip mounting area is connected to the boss and conductive adhesive dots. The conductive adhesive dots are flattened by the mounting area and have the same height as the boss. The mounting area extends and is connected to a frequency adjustment area located in the middle, including a first frequency adjustment area and a second frequency adjustment area.

[0035] The PAD has a conductive adhesive layer area, which is divided in the middle by a boss. The boss is 0.03mm wide and 0.02mm high. The conductive adhesive is applied to both sides of the boss. The chip mounting area is placed on the PAD base and above the conductive adhesive, and pressed down to half of the adhesive dots. The adhesive dots and the PAD boss are parallel, and the adhesive dots are separated by the PAD boss. This does not increase the impedance of the crystal, but improves the parallelism of the chip mounting, thereby ensuring the stability and reliability of the product.

[0036] After being flattened by the mounting area, the conductive adhesive dots are aligned with the height of the boss. By controlling the dispensing amount and assembly pressure, the flexible conductive adhesive undergoes controlled deformation (flattening) under pressure. This ensures parallelism; the flattened adhesive dots precisely fill the minute gap between the bottom surface of the wafer mounting area and the top surface of the boss, forming a completely flat support plane together with the boss. The wafer is then firmly supported on this plane formed by the rigid boss and the cured conductive adhesive. This eliminates wafer tilting (non-parallelism) caused by uneven adhesive dot height or an uneven base.

[0037] Stress homogenization is achieved by combining four-point support (the boss provides the main support surface, and the adhesive dots assist in fixing and filling) with flattening to achieve the same height, so that the mechanical stress (from fixing) on ​​the wafer is more evenly distributed and local stress concentration is reduced.

[0038] The mounting area extends to a central frequency adjustment area, a typical structural feature of the chip itself (tuning fork arm), used for fine-tuning the frequency. The key to this solution is ensuring the stability and reliability of the mounting base (mounting area) for this critical vibration region. Precisely ensuring chip parallelism directly addresses the core issue of "ensuring chip parallelism after mounting." Parallelism is a critical mechanical factor affecting frequency stability. Chip tilt leads to asymmetrical stress, uneven internal stress distribution during vibration, affecting resonant frequency stability (temperature drift, aging); deterioration of vibration modes, potentially exciting unwanted vibration modes and interfering with the stability of the master mode; and the risk of interference with the base / cover plate. In miniaturized products, tilt may increase the risk of collisions, affecting reliability. Significantly improving frequency stability is the direct goal, achieved by eliminating tilt (parallelism) and reducing frequency drift (temperature drift, aging drift) caused by mounting asymmetry. Uniform support (boobs + flattened adhesive dots) makes the stress distribution more even during chip vibration, resulting in a purer and more stable master mode. A stable, stress-free mounting base reduces the chip's sensitivity to external mechanical stress (impact, vibration) and temperature changes. This design does not increase impedance (and may even optimize it). The boss provides the main rigid support, while the conductive adhesive primarily serves for electrical connection and auxiliary fixation, without bearing the main support load (avoiding excessive static stress caused by excessive adhesive thickness or curing shrinkage). Flattening ensures height matching, guaranteeing tight contact between the wafer and the boss, providing a good heat conduction path (the ceramic substrate dissipates heat well), which helps stabilize the operating temperature and indirectly contributes to impedance stability. It also avoids introducing additional damping due to excessive adhesive thickness. The symmetrical four-dot adhesive application is more precise and controllable compared to potentially uneven application methods, reducing the risk of loss due to excess adhesive. Stress homogenization also reduces changes in equivalent resistance caused by stress.

[0039] The wafer is firmly secured by rigid bosses and cured adhesive dots, enhancing its resistance to impact and vibration. Reduced stress failure, uniform support, and low-stress mounting lower the risk of wafer cracking due to long-term stress or thermal cycling. Avoiding interference, excellent parallelism reduces the risk of the wafer hitting the inner wall of the base or cover plate when vibrating in a confined space.

[0040] The boss serves as a reference, providing a clear physical reference for dispensing and placing wafers, reducing the absolute dependence of assembly on operator experience. Four-point dispensing offers controllable quantity; compared to large-area or linear dispensing, the amount and location of four-point dispensing are easier to control precisely (through automated dispensing equipment). "Flattening to the same height" is the target state, providing a clear objective for setting and optimizing process parameters (dispense quantity, pressure).

[0041] The inner cavity is 1.5~1.8mm long and 0.6~1.0mm wide. The base PAD is close to the edge of the inner cavity, with a length of 0.40~0.46mm and a width of 0.19~0.23mm. (See attached...) Figure 2 , 3 The widths of the inner cavities a and b of the base are designed to be 1.66 mm and 0.80 mm, respectively. The wafer size design must meet the following requirements: length less than 85% of the inner cavity of the base, and width less than 70% of the inner cavity of the base. The length of the wafer is 1.39~1.43 mm, and the width is 0.54~0.58 mm. Therefore, the wafer length L is designed to be 1.41 mm, and the wafer width W is designed to be 0.56 mm. Due to the dispensing equipment's accuracy of ±0.01 mm, the length of the mounting area is 0.42~0.48 mm, and the width is 0.07~0.11 mm. Therefore, the wafer mounting length f is designed to be the size of the base PADc plus the equipment accuracy, 0.45 mm. The wafer mounting width g is designed to be half the maximum dispensing width, 0.09 mm. The edges of the mounting area have a chamfered structure.

[0042] Extremely miniaturized to fit thin and light devices, with an internal cavity width of only 0.6~1.0mm, corresponding to the 1610 package (1.6mm×1.0mm) or the smaller 1210 package (1.2mm×1.0mm), meeting the needs of smartphones / wearable devices for miniature crystal oscillators.

[0043] The base PAD is placed close to the edge of the cavity, maximizing the use of the cavity width and providing a rigid support boundary for the wafer, reducing the risk of vibration displacement.

[0044] The PAD (Pad Array) has a high length ratio (67%~76%), reaching 0.40~0.46mm within a limited width (0.6~1.0mm), almost filling the entire width of the inner cavity. This increases the contact area between the PAD and the ceramic substrate, improves mechanical strength, and suppresses deformation caused by temperature changes.

[0045] The PAD width is 0.19~0.23mm, providing precise layout space for the boss and the conductive adhesive dots on both sides. The boss needs to be centered (width approximately 0.1mm); the conductive adhesive dots on both sides need to be symmetrical (single adhesive dot diameter approximately 0.05~0.08mm).

[0046] Tolerance control at small dimensions requires an internal cavity tolerance of ±0.05mm and a PAD tolerance of ±0.015mm, demanding micron-level machining precision. Ensuring the height consistency of symmetrical PADs prevents wafer tilting due to uneven base. When the PAD width is 0.23mm, the boss width is approximately 0.1mm, with 0.06mm space reserved on each side to accommodate conductive adhesive dots. Through precise dimensional chain control, the process goal of "flattened adhesive dots at the same height as the boss" is achieved, fundamentally guaranteeing parallelism.

[0047] Short conductive paths and PADs positioned close to the edge shorten electrode lead length; small internal cavity size reduces signal transmission distance. This also reduces parasitic inductance / resistance, preventing impedance increases due to miniaturization and meeting the constraint of "no increase in impedance."

[0048] The inner cavity length is 1.5~1.8mm, and the total length of the tuning fork crystal is typically 1.2~1.4mm (mounting area + vibrating arm), with a 0.3~0.4mm margin reserved in the inner cavity length. This provides a non-contact buffer space for the frequency adjustment area (tuning fork arm), preventing collisions with the cavity wall during vibration and ensuring Q value and stability.

[0049] The width of the boss is 0.02~0.04mm, and the height is 0.01~0.02mm. The width of 0.02~0.04mm (20~40μm) ensures precise positioning within the limited PAD width (0.19~0.23mm), avoiding encroachment on the conductive adhesive space. Less than 1 / 5 of the PAD width (based on a minimum PAD width of 0.19mm), it ensures a space of ≥0.075mm on each side to accommodate the conductive adhesive dots (typically 50~80μm in diameter). The height of 0.01~0.02mm (10~20μm) defines the theoretical gap between the chip and the PAD, providing precise deformation tolerance for the flattening of the conductive adhesive. The boss height of 0.01~0.02mm sets the target thickness for the flattened adhesive dots; the initial height of the adhesive dots should be slightly higher than the boss (e.g., 0.03mm), and the same height after flattening. The boss width is 0.02~0.04mm, providing rigid support area. It is necessary to balance strength (to prevent breakage) and clearance (to not interfere with the leveling of adhesive dots).

[0050] Combined with appendix Figure 2 , 4 The dispensing diameter requirement is 0.14~0.18mm, and the height of the conductive adhesive dot is 0.05~0.07mm. Based on the maximum dot diameter of 0.18mm, and considering the dispensing equipment accuracy of ±0.01mm, the symmetrical base PADs are designed with a diameter of 0.20mm. The width d of the boss is designed to be 0.03mm, and the total length c is 0.43mm. Since the Kovar ring manufacturing tolerance is ±0.02mm, and considering the dispensing equipment accuracy of ±0.01mm, the width e of the PAD is designed to be 0.21mm.

[0051] Combined with appendix Figure 4 The conductive adhesive dots are pressed down to a height greater than half the height of the adhesive dots in the mounting area. The mounting height of the adhesive dots requires the chip to be pressed down to a height greater than half the height of the adhesive dots. The minimum height of the adhesive dots is 0.05mm, therefore the height of the PAD's protrusion t is designed to be 0.02mm.

[0052] The present invention and its embodiments have been described above illustratively. This description is not restrictive, and the figures shown are only one embodiment of the present invention; the actual structure is not limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the inventive spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A high-stability tuning fork crystal resonator, characterized in that, The device includes a ceramic base with an inner cavity. The inner cavity contains a wafer and symmetrically arranged base PADs. The base PADs have a protrusion in the middle and conductive adhesive dots on both sides of the protrusion. The wafer mounting area is connected to the protrusion and the conductive adhesive dots. The conductive adhesive dots are flattened by the mounting area and have the same height as the protrusion. The mounting area extends and is connected to a frequency adjustment area located in the middle.

2. The high-stability tuning fork crystal resonator according to claim 1, characterized in that, The inner cavity has a length of 1.5~1.8mm and a width of 0.6~1.0mm. The base PAD is close to the edge of the inner cavity. The base PAD has a length of 0.40~0.46mm and a width of 0.19~0.23mm.

3. A high-stability tuning fork crystal resonator according to claim 2, characterized in that, The width of the boss is 0.02~0.04mm, and the height of the boss is 0.01~0.02mm.

4. A high-stability tuning fork crystal resonator according to claim 1, characterized in that, The length of the crystal is 1.39~1.43mm, and the width of the crystal is 0.54~0.58mm.

5. A high-stability tuning fork crystal resonator according to claim 4, characterized in that, The length of the mounting area is 0.42~0.48mm, and the width of the mounting area is 0.07~0.11mm.

6. A high-stability tuning fork crystal resonator according to claim 5, characterized in that, The edges of the mounting area are chamfered.

7. A high-stability tuning fork crystal resonator according to claim 1, characterized in that, The conductive adhesive dots are pressed down by the mounting area to a size greater than 1 / 2 of the conductive adhesive dots.

8. A high-stability tuning fork crystal resonator according to claim 7, characterized in that, The height of the conductive adhesive dots is 0.05~0.07mm.

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