Crystal oscillator optimization process, crystal oscillator manufacturing process and temperature control equipment

Abstract

This invention provides an optimized process for crystal oscillators, comprising: curing and passivating a primary crystal oscillator sample after adhesive dispensing; the curing and passivation are performed in the same equipment, wherein the equipment heats the primary crystal oscillator sample under vacuum conditions and maintains different temperature environments. This application also provides a crystal oscillator manufacturing process. In the optimized crystal oscillator process provided by this application, the curing and passivation are performed in the same equipment, eliminating the need to transfer from a curing furnace to a passivation furnace. Instead, curing and passivation are performed directly in the same equipment under vacuum conditions, achieving rapid curing of the silver paste on the primary crystal oscillator sample, avoiding the problem of abnormal nitrogen supply during the curing process, reducing the amount of nitrogen supplied, and ensuring the quality of the crystal oscillator.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of crystal oscillator, in particular to an optimized process of crystal oscillator, a production process of crystal oscillator and a temperature control device. BACKGROUND

[0002] In the production process of crystal oscillator, there are many process flows, which generally include the following steps in sequence: piece arranging (BA), cleaning (BC), sputtering (BP), dispensing (AM), curing (CO), fine tuning (FA) and sealing (SM). After the dispensing (AM) is completed, high-temperature curing (CO) is needed to be performed as soon as possible to ensure product quality, and the wafer after dispensing is baked to accelerate the curing of the glue and the fixation of the connection between the wafer and other components.

[0003] With the development of technology and the increasing requirements for crystal oscillator products, it is necessary to ensure the frequency stability of the crystal oscillator products as much as possible before the final sealing, so that a passivation process (VA) is added before the sealing, that is, the process flow becomes piece arranging (BA), cleaning (BC), sputtering (BP), dispensing (AM), curing (CO), fine tuning (FA), passivation (VA) and sealing (SM). At the same time, the related equipment needs to be increased, and the time required for the whole process flow will be prolonged.

[0004] In addition to the prolonged turnover time, the above production process also consumes a large amount of nitrogen and electricity. The curing is a process of effectively curing the hard glue on the surface of the product after dispensing in the curing furnace within a fixed time. The curing furnace is a semi-open tunnel hot air type drying furnace, which is divided into five temperature zones. The primary product of the crystal oscillator after dispensing is forwarded in the chain according to a fixed speed and completes the heating in the furnace, and the process time is about 90 minutes. The specific temperature-time diagram is shown in FIG. 1. Unlike the passive heating of the curing furnace, the passivation furnace is actively heated. The curing furnace is a stable temperature interval waiting for the primary product of the crystal oscillator on the chain to pass through and heat, while the passivation furnace is actively heated or heat preserved at a set temperature range with the primary product of the crystal oscillator being stationary placed in the vacuum cavity of the furnace body. The whole process of passivation, including vacuumizing, temperature rising, heat preserving and temperature falling, takes about 8 hours. The specific temperature-time diagram is shown in FIG. 2. Figure 1 Figure 2

[0005] During the curing process, high-purity nitrogen needs to be continuously input to ensure the low-oxygen environment inside. In general, the oxygen content in the furnace is required to be less than 5-20 ppm. The oxygen content inside the curing furnace is required to be harsh, and the continuous input of high-purity nitrogen must be maintained to meet the process requirements of the crystal oscillator production. If the high-temperature crystal oscillator product contacts oxygen, it will be completely scrapped.

[0006] ​​In addition, in the crystal oscillator production process, when encountering external nitrogen supply abnormality, the curing furnace only alarms, and the chain in the high-temperature furnace does not stop, so the curing furnace cannot be quickly stopped, and the risk of internal material abnormality is high; and when running, the internal temperature of the furnace exceeds 200℃, and emergency stop will cause the internal chain to deform due to uneven heating.

[0007] In view of the above description, it is urgent to provide a brand new crystal oscillator production process to solve the problems of high nitrogen consumption and abnormal supply in the curing process, and to ensure product quality. SUMMARY

[0008] The technical problem solved by the present application is to provide an optimized process for crystal oscillator, which can quickly realize the curing and stress relief of silver glue in one device, avoid the problem of nitrogen supply abnormality in the curing process, and ensure the quality of crystal oscillator.

[0009] Therefore, the present application provides an optimized process for crystal oscillator, characterized in that it comprises:

[0010] The point-glued crystal oscillator primary product is cured and passivated;

[0011] The curing and passivation are carried out in the same device, and the device heats and maintains different temperature environments for the crystal oscillator primary product under vacuum conditions.

[0012] Preferably, the vacuum degree of the vacuum condition is 0.5E-4Pa to 1.5E-4Pa.

[0013] Preferably, the different temperature environments consist of first-stage heating and second-stage heating.

[0014] The temperature of the first-stage heating is 170 to 190℃, and the holding time is 50 to 100min.

[0015] The temperature of the second-stage heating is greater than 260℃ and less than 300℃, and the holding time is 100 to 150min.

[0016] Preferably, the temperature of the first-stage heating is 175 to 188℃, and the holding time is 55 to 85min; the temperature of the second-stage heating is 270 to 295℃, and the holding time is 120 to 140min.

[0017] Preferably, the temperature of the first-stage heating is 175 to 188℃, and the holding time is 55 to 85min; the temperature of the second-stage heating is 270 to 295℃, and the holding time is 120 to 140min.

[0018] Preferably, after heating, the temperature is lowered and the vacuum of the device is stopped, and at the same time, protective gas is filled into the device.

[0019] Preferably, the protective gas is helium, the filling time is 3-10s; the temperature of the filled protective gas is 265-295℃.

[0020] Preferably, after the temperature of the cooling is lower than 90-120℃, nitrogen is filled into the device to normal pressure.

[0021] The application also provides a production process of a crystal oscillator, which comprises the following steps of arranging, cleaning, sputtering, dispensing, optimizing, fine-tuning and sealing in sequence; the optimizing is the optimizing process described in the above scheme.

[0022] The application also provides a temperature control device for the optimizing process, wherein the optimizing process is performed in the temperature control device.

[0023] The application provides an optimizing process of a crystal oscillator, which specifically comprises curing and passivating a crystal oscillator primary product after dispensing, wherein the curing and the passivating are performed in the same device, and the device heats and maintains different temperature environments for the crystal oscillator primary product under vacuum conditions. The optimizing process of the crystal oscillator provided by the application directly performs the curing and the passivating in the same device under vacuum conditions without transferring the crystal oscillator primary product from a curing furnace to a passivating furnace, realizes rapid curing and stress relief of silver glue of the crystal oscillator primary product, avoids problems of abnormal nitrogen supply during the curing process, reduces the supply amount of nitrogen, and ensures the quality of the crystal oscillator.

[0024] Further, the different temperature environments involved in the optimizing process of the crystal oscillator provided by the application are composed of first-stage heating and second-stage heating, and by controlling relevant parameters, the time of the first-stage heating, i.e., the curing, is prolonged, and the linear heating process under high vacuum is far superior to the heat air drying+chain conveying sudden temperature rise in the prior art, which ensures the stability of the electrical properties of the crystal oscillator; the second-stage heating further eliminates the internal stress of the crystal oscillator primary product, and the crystal oscillator primary product does not need to be cooled again and contacted with air, but directly enters the passivation, which can make the internal frequency of the crystal oscillator more stable. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A temperature-time curve diagram of the curing in the crystal oscillator preparation process in the prior art;

[0026] Figure 2 A temperature-time curve diagram of the passivation in the crystal oscillator preparation process in the prior art;

[0027] Figure 3 A temperature-time curve diagram of the optimizing process of the crystal oscillator provided by the application;

[0028] Figure 4 A production flowchart of the improved crystal oscillator process and a production flowchart of the crystal oscillator of the application;

[0029] Figure 5 A temperature-time curve diagram of an optimized process in a crystal oscillator preparation process provided for the embodiment 1 of the present application;

[0030] Figure 6 A temperature-time curve diagram of a solidification in a crystal oscillator preparation process provided for the comparative example 1 of the present application;

[0031] Figure 7 A process data table of a solidification in a crystal oscillator preparation process provided for the comparative example 1 of the present application;

[0032] Figure 8 A temperature-time curve diagram of a passivation in a crystal oscillator preparation process provided for the comparative example 1 of the present application. DETAILED DESCRIPTION

[0033] In order to further understand the present application, the preferred embodiments of the present application are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present application, and are not limitations to the claims of the present application.

[0034] In the crystal oscillator production process in the prior art, the solidification process conditions are harsh, the nitrogen supply amount is high, and the problems in the supply bring a series of problems. In the research process, the applicant found that after trimming, the crystal oscillator would have frequency drop. In order to solve this problem, the applicant further improved the production method of the crystal oscillator without changing the production equipment, specifically: chip arrangement (BA)-cleaning (BC)-sputtering (BP)-dispensing (AM)-solidification (CO)-passivation (VA)-trimming (FA)-soldering (SM), but the improved process still does not solve the nitrogen supply problem. After in-depth research, the present application provides an optimized process for a crystal oscillator, which performs solidification and passivation in the same equipment, discards the process means of "CO→VA" performed in different equipment, does not need to be transferred and cooled, and directly performs solidification and passivation in a vacuum environment, that is, the crystal oscillator primary product after dispensing does not need to be solidified by the silver glue through the tunnel type fixed furnace, but is rapidly solidified and stress relieved in one equipment. Thus, a series of problems in the solidification furnace are avoided, the nitrogen flow is saved, and the quality of the crystal oscillator is ensured. Specifically, the embodiment of the present application discloses an optimized process for a crystal oscillator, comprising:

[0035] The crystal oscillator primary product after dispensing is solidified and passivated.

[0036] The solidification and passivation are performed in the same equipment, and the equipment heats and maintains different temperature environments for the crystal oscillator primary product under vacuum conditions.

[0037] The optimized process for a crystal oscillator provided by the present application is for the crystal oscillator primary product after dispensing.

[0038] In the optimization process, the primary crystal oscillator after dispensing is solidified and passivated in the same device, that is, the optimization process realizes rapid solidification of silver glue in the primary crystal oscillator and pre-elimination of stress.

[0039] In the present application, the solidification and passivation are performed in the same device, and the device is used to heat the primary crystal oscillator under vacuum conditions and at different heating temperatures respectively.

[0040] Specifically, the device can be a heating device or a passivation furnace, and can realize vacuum conditions and heating.

[0041] According to the present application, after the primary crystal oscillator is placed in the device, it is vacuumized so that the device is in a vacuum condition, and the vacuum degree of the vacuum condition is 0.5E-4Pa-1.5E-4Pa; specifically, the vacuum degree of the vacuum condition is 0.8E-4Pa-1.2E-4Pa.

[0042] Then, the first stage heating and the second stage heating are sequentially started for solidification and passivation, and the process flow diagram is shown in Figure 3 Specifically, the temperature of the first stage heating is 170-190℃, the holding time is 50-100min, the temperature of the second stage heating is greater than 260℃ and less than 300℃, and the holding time is 100-150min; the heating rate of the first stage heating is 1-5℃ / min, and the heating rate from the first stage to the second stage is 3-5℃ / min. The solidification and passivation of the primary crystal oscillator are completed by the first stage heating and the second stage heating which are sequentially performed according to the present application. In the first stage heating, the silver glue is rapidly solidified, and this temperature is the temperature that meets the gradual solidification of the silver glue (single-component silane-based conductive adhesive). If the temperature is lower than this temperature range, the adhesion effect of the silver glue will be poor. It is a process of normal temperature-vacuum-linear slow heating, which prolongs the solidification time, and the linear heating process under high vacuum is much better than the sudden temperature rise in the prior art, which ensures the stability of the crystal oscillator. The heating and holding of the second stage heating further eliminate the internal stress of the crystal oscillator, and there is no need to cool down and contact air before the second stage heating, and the crystal oscillator can be directly passivated, which makes the internal frequency of the crystal oscillator more stable. In this process, in addition to considering the elimination of stress, the high temperature resistance of the passivation furnace also needs to be considered. If the temperature exceeds 300℃, it will have a negative impact on the solidified silver glue. Figure 3The temperature rising rate of the first stage heating and the temperature rising rate of the second stage heating are slower than the temperature rising rate of solidification and passivation in the prior art, because too fast heating rate will cause abnormal increase of impedance related parameters such as RR, DLD2 and RLD2. Further, the temperature of the first stage heating is 175-188℃, and the holding time is 55-85 min; the temperature of the second stage heating is 270-295℃, and the holding time is 120-140 min.

[0043] After the above heating is completed, the device is cooled and vacuum is stopped, and at the same time, protective gas is filled into the device at 265-295℃, the protective gas is helium, and the filling time is 3-10 s, so as to accelerate the cooling rate, achieve the effect of rapid cooling, and ensure the stability of the product frequency. According to the present application, after the temperature is lowered to 90-120℃, nitrogen is filled into the device to normal pressure, so as to ensure the quality of the crystal oscillator primary product.

[0044] The present application also provides a production process of a crystal oscillator, which comprises the steps of arranging, cleaning, sputtering, dispensing, optimizing, fine tuning and sealing in sequence, and the optimizing is the optimizing process described in the above scheme.

[0045] The improved production process of the crystal oscillator provided by the applicant is shown in Figure 4 The optimizing process provided by the present application combines solidification and passivation in the same device.

[0046] Specifically, in the production process of the crystal oscillator, the arranging, the cleaning, the sputtering, the dispensing, the fine tuning and the sealing are all technical means familiar to those skilled in the art, and the present application does not make special limitations thereon.

[0047] Further, the present application also provides a temperature control device for the above optimizing process, and the optimizing process is carried out in one temperature control device.

[0048] Specifically, the temperature control device can be a heating device or a passivation furnace, and can realize vacuum condition and heating.

[0049] The present application provides an optimizing process of a crystal oscillator, which combines solidification and passivation in the same device, saves the consumption of nitrogen (according to statistics, the cost saving per month can reach at least 60,000 RMB), and the production method can ensure the quality of the crystal oscillator.

[0050] In order to further understand the present application, the production method of the crystal oscillator provided by the present application is described in detail below in combination with examples, and the protection scope of the present application is not limited by the following examples.

[0051] Example 1

[0052] Cutting and grinding treatment is performed on the quartz crystal raw material to obtain a quartz wafer;

[0053] The quartz wafer is cleaned, a silver layer is sputtered on the quartz wafer, and the quartz wafer with the silver layer is fixed on the base using conductive glue to obtain a crystal oscillator primary product;

[0054] The crystal oscillator primary product (frequency point selected as 25MHz) is placed in a passivation furnace, and the furnace door is closed; the passivation furnace is first evacuated, and when the vacuum reaches 1.0E-4Pa, heating is started;

[0055] When the temperature in the furnace reaches 180℃, the temperature is maintained for 80min; after the temperature is maintained, the temperature is continuously increased to 280℃, and the temperature is maintained for 140min;

[0056] During the above heating and temperature maintaining stage, the vacuum pump does not stop to evacuate to discharge the gas and other components generated by the product under high temperature;

[0057] After the temperature is maintained, the main valve is closed, the vacuum is stopped, and helium is filled into the cavity for 5 seconds to protect the product from oxidation and accelerate cooling;

[0058] After the temperature in the furnace is reduced to below 100℃, the furnace is filled with nitrogen to normal atmospheric pressure, the furnace door is opened, and the product can be taken out. The above process is specifically shown in Figure 5 ; the passivated crystal oscillator primary product is fine-tuned and sealed to obtain a crystal oscillator.

[0059] Comparative Example 1

[0060] Cutting and grinding treatment is performed on the quartz crystal raw material to obtain a quartz wafer;

[0061] The quartz wafer is cleaned, a silver layer is sputtered on the quartz wafer, and the quartz wafer with the silver layer is fixed on the base using conductive glue to obtain a crystal oscillator primary product;

[0062] The crystal oscillator primary product (frequency point selected as 25MHz) is placed in a chain type curing furnace and heated to 185℃ in a nitrogen atmosphere, and the temperature is maintained for 50min; then the temperature is continuously increased, and the time in the temperature range of 190-240℃ is 9min; the temperature is increased to 245℃ and maintained for 5min, and then reduced to normal temperature in about 25min and transferred to a passivation furnace; the temperature-time curve and index of the curing furnace are shown in Figure 6 、 Figure 7 After the crystal oscillator primary product is transferred to the passivation furnace, the temperature is increased to 255℃ at normal temperature in a high vacuum atmosphere and maintained for 4 hours, and then helium is filled for 5s to reduce the temperature. The temperature-time curve of the passivation furnace is shown in Figure 8 .

[0063] After the primary product of the passivated crystal oscillator is fine-tuned, it is sealed by welding to obtain the crystal oscillator.

[0064] The performance of the crystal oscillator prepared in the examples and the comparative examples is detected, and the results are shown in Table 1.

[0065] Table 1 Performance data table of the crystal oscillator prepared in the examples and the comparative examples

[0066] Group RR C0 C1 TS FDLD DLD2 RLD2 DLDH2 CL FL Example 25.94 0.93 3.24 4.53 0.67 0.79 26.35 0.51 -0.12 24977017 Comparative Example 26.48 0.92 3.23 4.52 0.60 0.53 26.61 0.22 1.19 24950297

[0067] In the table, RR represents the starting impedance of the quartz oscillator, and the unit is Ω.

[0068] C0 static capacitance: the capacitance value between the two ends of the crystal is simply calculated, that is, the capacitance value under the external electronic circuit, and the unit is PF.

[0069] C1 dynamic capacitance: the value is related to the size of the electrode design, and the unit is fF.

[0070] TS: adjustment sensitivity of load measurement - when the load capacitance changes, the influence on the frequency change of the crystal, and the unit is ppm / PF.

[0071] FDLD: the difference between the maximum Fr and the minimum Fr under different excitation powers, and the unit is PPM.

[0072] DLD2: the difference between the maximum impedance and the minimum impedance obtained when driving the XTAL under different powers, which is called DLD2, and the unit is Ω.

[0073] RLD2: the maximum impedance value obtained when driving the XTAL under different powers, which is called RLD2, and the unit is Ω.

[0074] DLDH2: the difference between the maximum impedance and the minimum impedance in the specified excitation power range, and the unit is Ω.

[0075] CL load capacitance: the load capacitance generated by the loaded resonant quartz oscillator, and the unit is PF.

[0076] FL load resonance frequency: if the load resonance frequency exceeds the specification, it will cause the oscillation frequency to deviate; the customer will not be able to generate the correct working frequency when applying, and the unit is Hz.

[0077] The performance of the crystal oscillator prepared in Example 1 and Comparative Example 1 is detected, and the results are shown in Table 1. The impedance-related curves under the two process flows and the frequency deviation of the aged products are observed. Through the observation of the data of RR, RLD2, DLD2, FDLD, etc., it is found that the performance of the crystal oscillator prepared in Example 1 is better, which meets the performance index of the industry.

[0078] To facilitate further aging test observation, the crystal oscillator frequency value was converted into a PPM value for recording and analysis. The conversion formula is as follows:

[0079] PPM value = [(Actual frequency - Set frequency) / Set frequency] x 1,000,000

[0080] The two sets of products were aged for 300 hours, and then for 706 hours. The frequency drop of the crystal oscillator after aging was analyzed, as shown in Table 2.

[0081] Table 2. Frequency drop data of crystal oscillators prepared in Example 1 and Comparative Example 1 after aging.

[0082]

[0083]

[0084] As can be seen from Table 2, the crystal oscillator prepared in Example 1 has a concentrated frequency point and a low frequency drop index after aging, which is better than Comparative Example 1, which was optimized by curing and passivation on two separate devices.

[0085] The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

[0086] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An optimization process for a crystal oscillator, characterized by, The application relates to a production process of a crystal oscillator, which comprises the following steps: solidification and passivation of the crystal oscillator after dispensing; the solidification and passivation are carried out in the same device, the device is used for heating the crystal oscillator under vacuum condition and keeping different temperature environments; the different temperature environments are composed of first-stage heating and second-stage heating; the temperature of the first-stage heating is 170-190 DEG C, and the holding time is 50-100 min; the temperature of the second-stage heating is greater than 260 DEG C and less than 300 DEG C, and the holding time is 100-150 min.

2. The process of claim 1, wherein, the vacuum degree of the vacuum condition is 0.5E-4 Pa-1.5E-4 Pa.

3. The process of claim 1 wherein, the temperature rising rate of the first-stage heating is 1-5 DEG C / min, and the temperature rising rate of the first-stage heating to the second-stage is 3-5 DEG C / min.

4. The process of claim 1 wherein, the temperature of the first-stage heating is 175-188 DEG C, and the holding time is 55-85 min; the temperature of the second-stage heating is 270-295 DEG C, and the holding time is 120-140 min.

5. The process of claim 1 wherein, after the heating, the device is cooled and vacuumized, and protective gas is filled into the device.

6. The process of claim 5, wherein, the protective gas is helium, the filling time is 3-10 s, and the temperature of the filled protective gas is 265-295 DEG C.

7. The process of claim 5, wherein, after the temperature of the cooling is lower than 90-120 DEG C, nitrogen is filled into the device to reach normal pressure.

8. A production process of a crystal oscillator, which comprises the following steps in sequence: piece arranging, cleaning, sputtering, dispensing, optimization, fine adjustment and welding sealing; the optimization is the optimization process in any one of claims 1-7.

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