A low-aging-rate quartz crystal device

Abstract

The utility model provides a kind of low aging rate quartz crystal device, including quartz wafer substrate, the upper surface and the lower surface of quartz wafer substrate are equipped with nickel-chromium alloy film layer, and one side of nickel-chromium alloy film layer principle quartz wafer substrate is equipped with gold film layer.The utility model reduces the aging rate of quartz crystal device, improves the service life of quartz crystal device, and is especially suitable for high-frequency quartz crystal device.

Description

Technical Field

[0001] This utility model relates to the field of quartz crystal product technology, and in particular to a quartz crystal device with low aging rate. Background Technology

[0002] With the widespread adoption of next-generation wireless communication technology Wi-Fi 7, the demand for high-stability and long-life crystals is increasing, especially for crystal products with high fundamental frequencies and low aging rates. These special crystals typically require an aging range of ±1 ppm in the first year or even ±2 ppm within five years. Aging ppm (Parts Per Million) is a unit of measurement used to describe the frequency drift of electronic components such as quartz crystals during long-term use.

[0003] The phenomenon of frequency change of quartz crystal elements over time is called aging. A high annual aging rate has many causes, related to various processes, and is one of the indicators reflecting a company's comprehensive technical expertise. Its mechanism mainly involves stress relaxation and mass adsorption effects. During the production of crystal oscillators, crystal manufacturers establish strict clean production lines to control dust accumulation, rigorously control contamination in process engineering, implement high-temperature annealing for stress release, vacuum packaging to prevent oxidation, and minimize the exposure time of electrodes to air to prevent oxidation and recontamination of the wafer. Based on this strict process control, the typical aging rate of low-frequency crystals with silver electrodes is ±2ppm / year, which can be optimized to ±1ppm / year.

[0004] However, under the same environmental conditions and technological level, the aging rate of high-frequency crystals is usually worse than that of low-frequency crystals, which is closely related to their physical structure, material properties, and operating mode:

[0005] (1) Stress sensitivity caused by structural differences: On the one hand, high-frequency crystals require thinner quartz wafers (e.g., about 27+ micrometers for 60MHz), while low-frequency crystals (e.g., about 84+ micrometers for 20MHz) have thicker wafers. Thinner wafers are more susceptible to mechanical stress and thermal expansion, making internal defects (dislocations, vacancies) more likely to migrate, accelerating structural relaxation and aging; on the other hand, high-frequency crystal electrodes are usually thinner and smaller in area, and the stress caused by the difference in thermal expansion coefficients between the electrodes and the wafer is more significant, exacerbating frequency drift.

[0006] (2) Surface effect and pollution sensitivity

[0007] On the one hand, the thin wafers of high-frequency crystals have a larger surface area to volume ratio, making the surface contamination (adsorbed gas, water molecules) have a more significant impact on the resonant frequency; on the other hand, high-frequency crystals have higher requirements for wafer flatness and edge roughness, and tiny defects (such as edge cracks) are more likely to expand during the aging process, causing performance degradation.

[0008] (3) Nonlinear effects of the material itself

[0009] High-frequency crystals often require higher excitation power when operating, which leads to an increase in local power density and more significant crystal heating. Even if the external temperature is constant, the lattice distortion caused by the internal thermal gradient will still accelerate aging (such as thermal frequency drift of quartz crystals). In addition, high-frequency vibration may also excite higher harmonics or non-ideal vibration modes of the crystal (such as insufficient energy trapping effect), resulting in energy loss and material fatigue accumulation.

[0010] (4) Packaging and process challenges

[0011] High-frequency crystal packaging requires thermal stress isolation within a very small space, but the difference in thermal expansion coefficients between thin wafers and packaging materials (such as ceramics and metals) is more difficult to coordinate, and the release of interface stress after long-term use will lead to frequency drift.

[0012] This presents a significant challenge for products with higher requirements for aging rates, especially for products with low aging rates and high frequency of use. Utility Model Content

[0013] To address the aforementioned issues, this invention provides a low-aging-rate quartz crystal device, aiming to optimize the aging rate of quartz crystal products.

[0014] A low-aging-rate quartz crystal device includes a quartz crystal substrate, wherein a nickel-chromium alloy film layer is provided on both the upper and lower surfaces of the quartz crystal substrate, and a gold film layer is provided on one side of the quartz crystal substrate.

[0015] Furthermore, the mass ratio of nickel to chromium in the nickel-chromium alloy film is 80:20.

[0016] Furthermore, the thickness of the nickel-chromium alloy film is less than that of the gold film.

[0017] Furthermore, the thickness of the nickel-chromium alloy film is 3-8 nm.

[0018] Furthermore, the thickness of the gold film layer is 80-150 nm.

[0019] Furthermore, the nickel-chromium alloy film layers on the upper and lower surfaces of the quartz wafer substrate are of the same thickness.

[0020] Furthermore, the gold film layers on the upper and lower surfaces of the quartz wafer substrate are of the same thickness.

[0021] Furthermore, the quartz crystal device also includes a base with a receiving groove;

[0022] A quartz wafer substrate with a nickel-chromium alloy film layer and a gold film layer is placed in a receiving groove.

[0023] Furthermore, one end of the quartz wafer substrate, which has a nickel-chromium alloy film layer and a gold film layer, is bonded to the bottom of the receiving groove with conductive adhesive.

[0024] Furthermore, the quartz crystal device also includes a top cover and a receiving groove on the top cover encapsulating the base.

[0025] The beneficial technical effects of this utility model are as follows: the two surfaces of the low-aging-rate quartz crystal device of this utility model are sequentially provided with a nickel-chromium alloy film layer and a gold film layer, which reduces the aging rate of the quartz crystal device and improves the service life of the quartz crystal device. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the structure of a low-aging-rate quartz crystal device according to the present invention;

[0027] Specifically,

[0028] 1- Quartz wafer substrate;

[0029] 2-Ni-Chromium alloy film;

[0030] 3-Gold film layer;

[0031] 4-Base;

[0032] 5-Conductive adhesive;

[0033] 6-Top cover. Detailed Implementation

[0034] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention.

[0037] See Figure 1 This utility model provides a low-aging-rate quartz crystal device, including a quartz crystal substrate (1), with a nickel-chromium alloy film layer (2) on both the upper and lower surfaces of the quartz crystal substrate (1), and a gold film layer (3) on one side of the quartz crystal substrate (1).

[0038] The low-aging-rate quartz crystal device of this invention has a nickel-chromium alloy film layer (2) and a gold film layer (3) sequentially disposed on both surfaces, which reduces the aging rate of the quartz crystal device and improves the service life of the quartz crystal device.

[0039] High-frequency crystals typically require an aging period of ±0.7 ppm in the first year, or even ±2 ppm within 5 years. Under the same environmental conditions and process levels, the aging performance of high-frequency crystals is usually worse than that of low-frequency crystals, which is closely related to their physical structure, material properties, and operating modes. This invention addresses the stress sensitivity caused by structural differences. The stress sensitivity caused by structural differences, specifically the stress caused by the difference in the thermal expansion coefficients between the electrodes and the wafer substrate, is more significant and exacerbates frequency drift.

[0040] Regarding adhesion to quartz, gold, silver, and quartz crystal substrates showed poor adhesion, while chromium and quartz crystals showed relatively strong adhesion.

[0041] In terms of matching the coefficient of thermal expansion of materials with quartz wafers, gold is superior to silver; among expansion-inhibiting materials, nickel-chromium is the best.

[0042] In terms of chemical stability, gold is superior to silver. Among expansion-inhibiting materials, chromium is the best, followed by nickel-chromium, and nickel is the worst.

[0043] Based on comprehensive considerations of adhesion to quartz, matching of thermal expansion coefficients, and chemical stability, this invention uses a nickel-chromium alloy as an intermediate transition layer. This provides optimized long-term stability, strong adhesion, and matching of thermal expansion coefficients. A gold film layer is then plated onto the nickel-chromium alloy. Gold, a material with good stability and high conductivity, is selected as the electrode material, and its thermal expansion coefficient is close to that of quartz, thus reducing thermal stress.

[0044] Specifically, the quartz crystal device is a high-frequency quartz crystal device.

[0045] Furthermore, the mass ratio of nickel to chromium in the nickel-chromium alloy film (2) is 80:20.

[0046] The material selected is an 80-20 nickel alloy, whose coefficient of thermal expansion is close to that of quartz.

[0047] Furthermore, the thickness of the nickel-chromium alloy film (2) is less than the thickness of the gold film.

[0048] Furthermore, the thickness of the nickel-chromium alloy film (2) is 3-8 nm.

[0049] Furthermore, the thickness of the gold film layer (3) is 80-150 nm.

[0050] Furthermore, the nickel-chromium alloy film layer (2) on the upper and lower surfaces of the quartz wafer substrate (1) has the same thickness.

[0051] Furthermore, the gold film layer (3) on the upper and lower surfaces of the quartz wafer substrate (1) has the same thickness.

[0052] Furthermore, the quartz crystal device also includes a base (4) having a receiving groove;

[0053] A quartz wafer substrate (1) with a nickel-chromium alloy film layer (2) and a gold film layer (3) is disposed in a receiving groove.

[0054] Furthermore, one end of the quartz wafer substrate (1) having a nickel-chromium alloy film layer (2) and a gold film layer (3) is bonded to the bottom of the receiving groove by conductive adhesive (5).

[0055] Furthermore, the quartz crystal device also includes a top cover (6), which encapsulates a receiving groove on the base (4).

[0056] The above are merely preferred embodiments of the present utility model and are not intended to limit the implementation methods and protection scope of the present utility model. Those skilled in the art should realize that any equivalent substitutions and obvious changes made based on the description and illustrations of the present utility model should be included within the protection scope of the present utility model.

Claims

1. A quartz crystal device with low aging rate, characterized in that, The invention includes a quartz wafer substrate, wherein a nickel-chromium alloy film layer is provided on both the upper and lower surfaces of the quartz wafer substrate, and a gold film layer is provided on the side of the nickel-chromium alloy film layer away from the quartz wafer substrate.

2. The low-aging-rate quartz crystal device as described in claim 1, characterized in that, The thickness of the nickel-chromium alloy film is less than the thickness of the gold film.

3. The low-aging-rate quartz crystal device as described in claim 1, characterized in that, The thickness of the nickel-chromium alloy film is 3-8 nm.

4. The low-aging-rate quartz crystal device as described in claim 1, characterized in that, The thickness of the gold film layer is 80-150 nm.

5. A low-aging-rate quartz crystal device as described in claim 2, characterized in that, The nickel-chromium alloy film layers on the upper and lower surfaces of the quartz wafer substrate have the same thickness.

6. The low-aging-rate quartz crystal device as described in claim 2, characterized in that, The gold film layer on the upper and lower surfaces of the quartz wafer substrate has the same thickness.

7. A low-aging-rate quartz crystal device as described in claim 1, characterized in that, The quartz crystal device further includes a base having a receiving groove; The quartz wafer substrate, which has the nickel-chromium alloy film layer and the gold film layer, is disposed in the receiving groove.

8. The low-aging-rate quartz crystal device as described in claim 7, characterized in that, One end of the quartz wafer substrate, which has the nickel-chromium alloy film layer and the gold film layer, is bonded to the bottom of the receiving groove by conductive adhesive.

9. A low-aging-rate quartz crystal device as described in claim 7, characterized in that, The quartz crystal device also includes a top cover that encapsulates the receiving groove on the base.

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