Miniaturized SMD crystal oscillator

Abstract

The invention relates to a miniaturized SMD crystal oscillator which comprises a shell, a quartz crystal and a circuit board, the quartz crystal is electrically connected with the circuit board, a cavity is formed in the bottom of the shell and extends downwards to be provided with a heat transfer plate, a heat dissipation groove is formed between the heat transfer plate and the shell, a first heat transfer hole is formed in the left side of the heat transfer plate, and a second heat transfer hole is formed in the right side of the heat transfer plate. The bottom of the housing is provided with a circuit board through a fastener, and the circuit board is provided with a plurality of pins. According to the SMD crystal oscillator, the quartz crystal, the control circuit board and the switching circuit board are arranged in the closed cavity, miniaturization and integration of the SMD crystal oscillator are achieved, the requirements of electronic equipment for element miniaturization and integration are met, meanwhile, the air tightness of the crystal oscillator is enhanced, and the service life of the crystal oscillator is prolonged; according to the SMD crystal oscillator, the manufacturing process of the SMD crystal oscillator is simplified, the requirements of fine steps such as accurate welding, bonding and sealing are reduced, the error rate is reduced, the production cost is reduced, and the production period is shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of crystal oscillators, and in particular relates to a miniaturized SMD crystal oscillator. Background Art

[0002] Patent number CN 106788319 A relates to a miniaturized SMD crystal oscillator. By forming a closed cavity with the bottom plate and the outer shell, the quartz crystal, the control circuit board and the adapter circuit board are arranged in the closed cavity, thereby reducing the volume of the SMD crystal oscillator itself and achieving miniaturization. At the same time, the airtightness of the crystal oscillator is ensured, and the service life of the crystal oscillator is improved. It has been widely used in electronic equipment. With the continuous development of electronic technology, the requirements for miniaturization and integration of electronic components are becoming higher and higher.

[0003] In order to achieve a higher level of integration, the existing technology installs the internal devices closely. Such a dense device layout restricts air flow and reduces heat dissipation, thus causing the device to overheat and affecting its stability and reliability.

[0004] Secondly, the SMD crystal oscillator in the prior art has a more complicated manufacturing process due to the tight layout of the components. The complicated manufacturing process often involves multiple delicate steps, such as precise welding, bonding and sealing. These steps require a high level of technical skills from the operators and have a certain error rate, which not only increases the production cost, but also prolongs the production cycle.

[0005] Finally, in actual applications of the prior art, "the base plate 5 and the outer shell 1 are connected by energy storage welding or laser sealing to form a closed cavity", which increases the airtightness of the crystal oscillator. However, since the connection points of the energy storage welding and laser sealing are relatively small, when facing external impact or vibration, the connection parts may break or fall off due to stress concentration, resulting in an insufficiently firm connection between the outer shell and the base plate, thereby affecting the sealing and reliability of the entire oscillator; in addition, this single connection method may cause material fatigue of the connection parts under long-term temperature changes and mechanical stress, reducing the connection strength, and ultimately damaging the integrity of the closed cavity. After moisture and contaminants invade the inside of the oscillator, they will damage the quartz crystal and other sensitive electronic components, thereby affecting the performance and service life of the oscillator.

[0006] Therefore, a new type of small oscillator is designed, which can simplify the manufacturing process and improve the heat dissipation effect while maintaining a closed cavity and airtightness, that is, a miniaturized SMD crystal oscillator with better thermal management in a limited space. Summary of the invention

[0007] The object of the present invention is to provide a miniaturized SMD crystal oscillator to solve the problems raised in the above background technology.

[0008] To achieve the above-mentioned purpose, the present invention provides the following technical solution: a miniaturized SMD crystal oscillator, comprising a housing, a quartz crystal and a circuit board, the quartz crystal being electrically connected to the circuit board, a cavity being provided at the bottom of the housing, a heat transfer plate being provided in the cavity extending downward, a heat dissipation groove being formed between the heat transfer plate and the housing, a first heat transfer hole being provided on the left side of the heat transfer plate, a second heat transfer hole being provided on the right side of the heat transfer plate, the circuit board being mounted on the bottom of the housing by fasteners, and the circuit board having a plurality of pins.

[0009] Preferably, the number of the pins is 4, which are divided into a1 a2 a3 a4, wherein a1 and a3 are L-shaped pins arranged diagonally, and a2 and a4 are rectangular pins arranged symmetrically.

[0010] Preferably, a1 and a3 are empty pins.

[0011] Preferably, a cold contact block is provided on the top of the inner wall of the housing and extends downward, and the indented shape of the cold contact block is consistent with the outer shape of the quartz crystal.

[0012] Preferably, the cold contact block is made of ceramic and is integrally formed with the housing;

[0013] Preferably, the size of the circuit board is larger than that of the housing, and the lowest point of the heat transfer plate and the housing are on the same horizontal line;

[0014] Preferably, the first heat transfer hole, the second heat transfer hole and the heat dissipation slot are interconnected.

[0015] Preferably, the fastener includes: expansion compartments are symmetrically provided on the front and rear sides of the bottom of the circuit board, fastening openings are opened at the positions of the expansion compartments on the circuit board, angle plates are provided on the inner sides of the fastening openings, and are divided into 4 areas by the angle plates, namely, a first fastening area, a second fastening area, a third fastening area and a flipping area, fastening angle strips are symmetrically provided on the front and rear sides of the bottom of the shell, and the fastening angle strips are divided into horizontal sides and vertical sides.

[0016] Preferably, the fastening corner strip is made of fluororubber.

[0017] Preferably, thermal conductive paste is filled between the quartz crystal and the cold contact block.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention realizes the miniaturization and integration of the SMD crystal oscillator by arranging the quartz crystal, the control circuit board and the adapter circuit board in a closed cavity, meets the requirements of electronic equipment for the miniaturization and integration of components, and at the same time enhances the air tightness of the crystal oscillator and prolongs the service life of the crystal oscillator; the present invention simplifies the manufacturing process of the SMD crystal oscillator, reduces the requirements of fine steps such as precise welding, bonding and sealing, reduces the error rate, reduces the production cost and shortens the production cycle; the present invention improves the corrosion resistance and insulation performance of the shell by coating a composite ceramic coating on the shell of a metal or ceramic material, and ensures the stable operation of the crystal oscillator; the present invention increases the contact area between the quartz crystal and the shell by integrally forming a cold contact block in the shell, and at the same time Thermal paste is filled between the quartz crystal and the cold contact block to reduce thermal resistance and improve the heat dissipation efficiency. The present invention also optimizes thermal management and improves the stability and reliability of components by designing a heat transfer plate and a heat dissipation groove, and setting a first heat transfer hole and a second heat transfer hole. The present invention improves and optimizes the connection method based on the basic welding connection method, and adds 4 additional fastening points, so that the connection part can better resist external impact or vibration, thereby improving the reliability of the oscillator, while avoiding breakage or falling off caused by stress concentration, long-term temperature changes, etc., and ensuring the strong airtightness of the cavity. The above components work together to enable the present invention to achieve miniaturization and integrated design, while maintaining high performance, meeting the requirements of electronic equipment for high reliability, long life and good heat dissipation performance of components, thereby ensuring its stable operation in various application scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0020] Figure 2 An exploded view of the present invention;

[0021] Figure 3 It is a schematic diagram of the three-dimensional structure of the circuit board in the present invention;

[0022] Figure 4 It is a schematic diagram of the three-dimensional structure of the housing in the present invention;

[0023] Figure 5 It is the first enlarged schematic diagram at a;

[0024] Figure 6 It is the second enlarged schematic diagram of position a;

[0025] Figure 7 It is a schematic diagram of a finished product of the present invention;

[0026] Figure 8 is a cross-sectional view of the finished product of the present invention;

[0027] Fig. 9 This is an enlarged schematic diagram of point b.

[0028] Numbers in the figure: 1-housing, 2-quartz crystal, 3-circuit board, 301-pin a1, 302-pin a2, 303-pin a3, 304-pin a4;

[0029] 4- Cavity,

[0030] 5-fastener, 501-expansion compartment, 502-fastening port,

[0031] 503-angle plate, 531-first fastening area, 532-second fastening area, 533-third fastening area, 534-turning area;

[0032] 504-fastening corner strip, 541-horizontal edge, 542-vertical edge;

[0033] 7-cold contact block, 8-heat transfer plate, 801-first heat transfer hole, 802-second heat transfer hole, 9-heat dissipation groove. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0035] Example 1

[0036] like Figures 1 to 9A miniaturized SMD crystal oscillator is shown, comprising a housing 1, a quartz crystal 2 and a circuit board 3. The quartz crystal 2 is electrically connected to the circuit board 3. A cavity 4 is provided at the bottom of the housing 1. A heat transfer plate 8 is provided in the cavity 4 extending downward. A heat dissipation groove 9 is formed between the heat transfer plate 8 and the housing 1. A first heat transfer hole is provided on the left side of the heat transfer plate 8. A second heat transfer hole 802 is provided on the right side of the heat transfer plate 8. The circuit board 3 is mounted on the bottom of the housing 1 through a fastener 5. The circuit board 3 has a plurality of pins. The number of pins is 4, which are divided into a1a2 a3 a4, a1 and a3 are L-shaped pins arranged diagonally, and a2 and a4 are rectangular pins arranged symmetrically; a1 and a3 are empty pins; a cold contact block 7 is provided on the top of the inner wall of the shell 1, and the indented shape of the cold contact block 7 is consistent with the shape of the quartz crystal 2; the cold contact block 7 is made of ceramic and is integrally formed with the shell 1; the size of the circuit board 3 is larger than the shell 1, and the lowest point of the heat transfer plate 8 and the shell 1 is on the same horizontal line; the first heat transfer hole, the second heat transfer hole 802 and the heat dissipation groove 9 are mutually connected; the fastener 5 includes: the front and rear sides of the bottom of the circuit board 3 are opposite to each other It is said that an expansion compartment 501 is provided, and fastening openings 502 are opened at the positions of the expansion compartment 501 on the circuit board 3. Corner plates 503 are provided inside the fastening openings 502, and are divided into four areas by the corner plates 503, namely, a first fastening area 531, a second fastening area 532, a third fastening area 533 and a flip area 534. Fastening corner strips 504 are symmetrically provided on the front and back sides of the bottom of the shell 1, and the fastening corner strips 504 are divided into horizontal edges 541 and vertical edges 542; the preparation material of the fastening corner strips 504 is fluororubber; thermal conductive paste is filled between the quartz crystal 2 and the cold contact block 7.

[0037] The present invention realizes the miniaturization and integration of the SMD crystal oscillator by arranging the quartz crystal 2, the control circuit board 3 and the adapter circuit board 3 in a closed cavity, meets the requirements of electronic equipment for the miniaturization and integration of components, and at the same time enhances the air tightness of the crystal oscillator and prolongs the service life of the crystal oscillator; the present invention simplifies the manufacturing process of the SMD crystal oscillator, reduces the requirements of fine steps such as precise welding, bonding and sealing, reduces the error rate, reduces the production cost and shortens the production cycle; the present invention improves the corrosion resistance and insulation performance of the shell 1 by coating a composite ceramic coating on the shell 1 of metal or ceramic material, and ensures the stable operation of the crystal oscillator; the present invention increases the contact area between the quartz crystal 2 and the shell 1 by integrally forming a cold contact block 7 in the shell 1, and at the same time increases the contact area between the quartz crystal 2 and the cold contact Thermal paste is filled between the contacts 7 to reduce thermal resistance and improve heat dissipation efficiency. The present invention also optimizes thermal management and improves the stability and reliability of components by designing the heat transfer plate 8 and the heat dissipation slot 9, and setting the first heat transfer hole and the second heat transfer hole 802. The present invention improves and optimizes the connection method based on the basic welding connection method, and adds 4 additional fastening points, so that the connection part can better resist external impact or vibration, thereby improving the reliability of the oscillator, while avoiding breakage or falling off caused by stress concentration, long-term temperature changes, etc., and ensuring the strong airtightness of the cavity 4. The above components work together to enable the present invention to achieve miniaturization and integrated design, while maintaining high performance, meeting the requirements of electronic equipment for high reliability, long life and good heat dissipation performance of components, thereby ensuring its stable operation in various application scenarios.

[0038] Example 2

[0039] like Figures 1 to 9 A miniaturized SMD crystal oscillator shown includes a housing 1, a quartz crystal 2 and a circuit board 3. It should be noted that the quartz crystal 2 is directly connected to the control circuit board 3 through a conductive pin to ensure direct signal transmission. A general crystal oscillator has two circuit boards 3, which are divided into a control circuit board 3 and a transfer circuit board 3. The two are connected by welding or surface mount technology (SMT) to achieve stable signal transmission. This embodiment adopts a single-board crystal oscillator design method, that is, only one circuit board 3 is used to integrate all components. The circuit board 3 is specifically made of a ceramic substrate or a flexible circuit material. By improving the integration and reducing external connections, the overall structure is simplified. By saving internal space, the crystal oscillator becomes more miniaturized and can be applied to scenarios with limited space.

[0040] First, the housing 1 is a protective structure of the oscillator, which not only provides physical protection for the internal components, but also plays the role of electromagnetic shielding and preventing external interference. In the SMD packaging technology, the oscillator is mounted on the PCB, and a closed cavity 4 is formed inside the housing 1. While ensuring its good airtightness, the heat dissipation of the oscillator also mainly depends on the following aspects: the material and design of the housing 1, the PCB layout, the working conditions of the crystal oscillator, and the air flow. Therefore, without considering the heat dissipation conditions of the oscillator when in use, the material of the housing 1 is generally limited to metal or ceramic materials. The metal material can be specifically copper or aluminum alloy to ensure that it has a certain mechanical strength and shielding effectiveness, while the ceramic material has good electrical insulation performance and high temperature resistance.

[0041] Based on the above background, this embodiment proposes a surface treatment technology of "metal ceramicization", with specific reference to the invention patent with patent announcement number CN115448705A, entitled "An Insulating Anticorrosion Composite Ceramic Coating and Its Preparation Method and Application", which specifically discloses the preparation components and preparation method of the ceramic coating:

[0042] The first step is to prepare a uniformly mixed composite ceramic powder by wet ball milling: the three powders are added into a ball mill according to the corresponding mass fraction ratio, anhydrous ethanol and zirconium balls are added, and the mixture is put into a ball mill for mechanical fusion, and then taken out and dried to obtain a uniformly mixed and dry composite ceramic powder;

[0043] The second step is to pre-treat the surface of the metal substrate to be sprayed: the surface of the metal substrate to be sprayed is sandblasted or ultrasonically cleaned, and the compressed air is blown dry

[0044] The third step is to thermally spray the substrate with the mixed powder as the spraying raw material: the atmospheric plasma spraying technology is used to spray the composite ceramic powder on the surface of the metal substrate. The fourth step is to perform laser remelting post-processing on the coating: the laser remelting technology is used to remelt the surface of the composite ceramic coating obtained in the third step, and the remelting depth is 20-100um.

[0045] Finally, an insulating and anti-corrosion composite ceramic coating with high density, high bonding strength, better mechanical properties, corrosion resistance and insulation properties is obtained. When applied to this embodiment, the material of the shell 1 is copper or aluminum alloy, and then the ceramic coating obtained by the above technology is coated, so that the shell 1 has good corrosion resistance and insulation properties, ensuring the stable operation of the crystal oscillator protected inside it; in addition, physical vapor deposition (PVD) or chemical vapor deposition (CVD) can also be used to prepare and form the ceramic coating.

[0046] Furthermore, the quartz crystal 2 is electrically connected to the circuit board 3, and the circuit board 3 is installed and connected with the shell 1 to form a closed cavity 4, that is, the quartz crystal 2 will be located in the shell 1, and when the top of the inner wall of the shell 1 is extended downward to be provided with a cold contact block 7, the concave shape of the bottom edge of the cold contact block 7 is consistent with the quartz crystal 2, and finally the quartz crystal 2 and the cold contact block 7 are in close contact; in this way, when the cold contact block 7 is limited to be made of ceramic, the contact between the quartz crystal 2 and the ceramic shell 1 can be increased to achieve rapid dissipation of heat; not only that, the thermal conductive paste can be filled between the quartz crystal 2 and the cold contact block 7, and the thermal conductive paste contains a large amount of metal or non-metallic powder (such as silver, copper, aluminum or zinc oxide, etc.), which is dispersed in a thermoplastic or thermosetting polymer matrix to improve the thermal conductivity of the material, that is, to reduce the thermal resistance between the quartz crystal 2 and the cold contact block 7 (shell 1), thereby achieving the purpose of improving the heat dissipation efficiency; wherein the shell 1 and the cold contact block 7 are prepared by integral molding.

[0047] Secondly, the quartz crystal 2 is the core component of the oscillator, which is selected for its high stability and low aging rate. It is mainly responsible for providing a stable frequency reference. The quartz crystal 2 generates a stable oscillation frequency in the circuit, which is mainly used to ensure the time synchronization and frequency control of electronic equipment; in the installation of the quartz crystal 2, it is usually fixed on the circuit board 3 and connected to the circuit board 3 through a conductive pin. The traditional through-hole technology is mainly reflected in: a certain number of pin holes are opened on the surface of the printed circuit board 3 (PCB), and then the conductive pins on the oscillator element are inserted into the pin holes for installation; the prior art discloses an SMD packaging technology, which is provided with a certain number of surface-mount crystal pins at the bottom of the oscillator, and then the component is directly mounted on the pad of the PCB, and fixed in position by welding technology such as reflow soldering or wave soldering. Since SMD components are usually smaller than traditional through-hole components, the crystal oscillator is more compact and miniaturization is finally achieved.

[0048] Therefore, this embodiment is also based on the SMD packaging technology, and 4 SMD pins are provided at the bottom of the circuit board 3. In practical applications, the number of pins of the SMD crystal oscillator can vary from 2 to more, and the design of the number of pins will also produce different functions, and the common ones are:

[0049] 2-pin crystal oscillator, providing the most basic frequency control function;

[0050] 3-pin crystal oscillators may contain an additional pin for ground or other functions in addition to the basic frequency output;

[0051] 4-pin crystal, which may include two frequency outputs, or an oscillator with additional control or adjustment features, etc.

[0052] A higher number of pins is used in temperature compensated crystal oscillators (TCXOs) or voltage controlled crystal oscillators (VCXOs).

[0053] In the present embodiment, there are at least one or two empty pins among the four SMD pins. Specifically, the pin on the bottom left front side of the circuit board 3 is a1, the bottom left rear side of the circuit board 3 is a2, the bottom right rear side of the circuit board 3 is a3, and the bottom right front side of the circuit board 3 is a4, wherein a1 and a3 are diagonally arranged L-shaped pins, and a2 and a4 are symmetrically arranged rectangular pins. The setting of the above empty pins can be set according to actual needs.

[0054] When a1 and a3 are empty pins, due to their L-shaped shape that fits the angle of the circuit board 3, such pins are easier to align with the pads during soldering, and can maintain good positioning even in the automated soldering process; at the same time, due to their smaller projection area, L-shaped pins occupy less space and are more suitable for miniaturized oscillators; and L-shaped pins can help disperse the stress during the soldering process and reduce the impact on the electrical connection pins;

[0055] When a2 and a4 are empty pins, they provide a larger contact area during welding, which helps to dissipate heat and provide better mechanical connection, which will be more conducive to thermal management and additional mechanical support; but the rectangular pins have too much space burden, so they are not suitable for miniaturized oscillators.

[0056] Finally, the four SMD pins in this embodiment, with a1 and a3 as empty pins, can facilitate welding alignment, while helping to disperse the stress during the welding process, reduce the impact on a2 and a4 during welding, and ensure the stable installation and operation of the oscillator.

[0057] In addition, the cutting angle and shape of the quartz crystal 2 will also affect its frequency and temperature characteristics. In the first issue of the Journal of Time and Frequency in January 2024, Yan Jiancheng et al. disclosed the design and implementation of a miniaturized, wide-temperature, high-precision temperature-compensated crystal oscillator, which describes the relevant technology of AT-cut crystals, and compensates for the influence of temperature on the crystal frequency through a specific cutting angle, thereby achieving better frequency-temperature stability; after the cutting angle of the AT-cut crystal is precisely designed, the curve of the crystal's frequency changing with temperature can be optimized. This cutting method utilizes the anisotropic properties of the quartz crystal 2, that is, the physical properties of the crystal (including frequency-temperature characteristics) in different directions will be different. When the crystal is cut until its frequency-temperature characteristic curve is adjusted to the best, its frequency drift within the operating temperature range can be reduced, which can significantly improve the performance of the crystal oscillator under different environmental conditions.

[0058] However, considering that the production cost of AT-cut crystals may be higher and more precise cutting and calibration are required, the present embodiment selects SC-cut quartz crystal 2. Specifically, SC-cut (Standard Cut) is a standard cutting method, which usually refers to a slight modification of AT-cut crystals to optimize certain performance parameters. The temperature stability is relatively good, and the existing production process of SC-cut crystals is relatively mature, which is suitable for applications that do not require extreme temperature stability or special characteristics but require good cost performance.

[0059] Example 3

[0060] For example, a miniaturized SMD crystal oscillator in Example 2 mainly includes a housing 1, a quartz crystal 2 and a circuit board 3, and the material properties of the housing 1 are used as the basic heat dissipation:

[0061] Without considering the heat dissipation conditions of the oscillator when in use, the shell 1 is specifically made of copper or aluminum alloy as the main material, and a composite ceramic coating is used as a surface coating to ensure that the shell 1 has good corrosion resistance, insulation performance and air tightness, and to ensure the stable operation of the crystal oscillator protected therein; then a cold contact block 7 made of ceramic material is extended downward from the top of the inner wall of the shell 1 to achieve rapid dissipation of heat by increasing the contact between the quartz crystal 2 and the ceramic shell 1; thermal conductive paste can also be filled between the quartz crystal 2 and the cold contact block 7 to reduce the thermal resistance between the quartz crystal 2 and the cold contact block 7 (shell 1), thereby achieving the purpose of improving the heat dissipation efficiency.

[0062] Furthermore, the size of the circuit board 3 is larger than the shell 1, that is, when the circuit board 3 is welded to the bottom of the shell 1, part of it will protrude from the shell 1, thereby achieving airtight protection for the quartz crystal 2 electrically connected at the top of the circuit board 3, so that a closed cavity 4 is formed inside the shell 1, and the cavity 4 extends downward to be provided with a heat transfer plate 8. The shape of the heat transfer plate 8 is consistent with the shape of the bottom of the shell 1, specifically a rectangular closed ring, and the heat transfer plate 8 and the lowest point of the shell 1 are on the same horizontal line, that is, when the circuit board 3 is welded to the bottom of the shell 1, the setting of the heat transfer plate 8 will further reduce the closed volume of the cavity 4, so a first heat transfer hole and a second heat transfer hole 802 are respectively opened on the left and right sides of the heat transfer plate 8, and there are at least 2 heat dissipation holes, which are used to promote the inflow, outflow and circulation of internal air to achieve heat and dissipation.

[0063] At the same time, the heat transfer plate 8 is arranged to form a heat dissipation groove 9 between it and the outer edge of the bottom of the shell 1. The heat dissipation groove 9, the first heat transfer hole and the second heat transfer hole 802 are designed to "interpenetrate each other in the closed space of the shell 1", which means that the heat dissipation groove 9, the first heat transfer hole and the second heat transfer hole 802 form a continuous airflow channel, which helps to achieve more efficient heat exchange; that is, the heat entering the heat dissipation groove 9 through the first heat transfer hole and the second heat transfer hole 802 can be conducted to the shell 1, effectively reducing the hot spot area on the circuit board 3. At the same time, the heat dissipation groove 9 serves as a channel for the flow of hot air inside it, providing an additional path for the heat dissipation, increasing the heat dissipation area and improving the heat dissipation efficiency.

[0064] Example 4

[0065] like Figures 1 to 9 A miniaturized SMD crystal oscillator shown in the figure is provided with heat transfer holes and heat dissipation grooves 9 in a closed cavity 4 based on the heat dissipation characteristics of its fixed material, forming a continuous airflow channel to achieve more efficient heat exchange, conduct heat to the housing 1 faster, and improve heat dissipation efficiency; but considering that excessive airflow exchange will affect the welding air tightness between the housing 1 and the circuit board 3 to a certain extent, a fastener 5 is also connected between the housing 1 and the circuit board 3, which is used to accurately limit the engagement between the housing 1 and the circuit board 3 through the fastener 5 before the housing 1 and the circuit board 3 are welded, and an adhesive is poured in the fastener 5, so that there are at least four limiting forces with a larger connection area that are inconsistent with the welding stress direction between the housing 1 and the circuit board 3, so as to avoid the crystal oscillator being subjected to external impact or vibration during use, or under the action of long-term temperature changes and mechanical stress, resulting in material fatigue at the solder joint connection part to reduce the connection strength, and finally causing the integrity of the closed cavity to be damaged, and moisture and pollutants will damage the quartz crystal 2 and other sensitive electronic components after invading the inside of the oscillator, thereby affecting the performance and service life of the oscillator.

[0066] like Figure 5 and Figure 6 The fastener 5 shown specifically comprises:

[0067] The expansion chambers 501 are symmetrically arranged on the front and rear sides of the bottom of the circuit board 3. The circuit board 3 is provided with fastening openings 502 at the positions of the expansion chambers 501. The size of the fastening openings 502 is smaller than that of the expansion chambers 501. The inside of the fastening openings 502 is provided with angled plates 503, and the angled plates 503 divide the fastening openings 502 into multiple areas, including a first fastening area 531, a second fastening area 532, a third fastening area 533 and a flip area 534. Starting from the third fastening area 533 in transverse direction, the third fastening area 533 is connected to the first vertical fastening area 531, the first fastening area 531 is connected to the semicircular flipping area 534, the flipping area 534 is connected to the second fastening area 532, and the second fastening area 532 ends at the transverse edge 541 of the angle plate 503; wherein the first fastening area 531 and the second fastening area 532 are vertical grooves arranged in parallel, and the first fastening area 531 is longer than the second fastening area 532.

[0068] Correspondingly, fastening angle strips 504 are symmetrically arranged on the front and back sides of the bottom of the shell 1. The fastening angle strips 504 are divided into horizontal sides 541 and vertical sides 542. The length of the vertical side 542 of the fastening angle strip 504 is equal to the total length of the first fastening area 531, the flip area 534 and the second fastening area 532. The length of the horizontal side 541 of the fastening angle strip 504 is equal to the length of the third fastening area 533. Except for the length, the height and width of the fastening angle strip 504 can be completely embedded in the fastening opening 502; that is, the staff will pour the adhesive into the expansion chamber 501 through the fastening opening 502 in advance. At this time, the guide of the circuit board 3 The feet are facing downward, the fastening opening 502 is facing upward, and the top is electrically connected to the quartz crystal 2. Then, just hold the shell 1, put the vertical side 542 of the fastening angle strip 504 through the first fastening area 531, and then bend it through the flip area 534 to enter the second fastening area 532 until the second fastening area 532 is filled. At this time, the horizontal side 541 of the fastening angle strip 504 is also completely stuck in the third fastening area 533. After a period of rest, the shell 1 and the circuit board 3 can be accurately positioned, and then the circuit board 3 and the remaining contact part of the shell 1 are connected by welding or other methods to form a closed cavity in the shell 1. As mentioned above, this embodiment not only ensures the airtightness of the connection between the shell 1 and the circuit board 3, but also provides 4 additional fastening points to achieve the fastening connection between the circuit board 3 and the shell 1. Even under the action of long-term temperature changes and mechanical stress, the material fatigue of the solder joint connection reduces the connection strength, and it will not cause too much impact on the airtightness.

[0069] Among them, the fastening angle strip 504 can be made of soft high temperature resistant material, including but not limited to silicone, fluororubber and butyl rubber; and in this embodiment, fluororubber is selected as the preparation material of the fastening angle strip 504, which has many advantages such as high temperature resistance, corrosion resistance, oxidation resistance, etc., and can work stably in the temperature range of -20°C to +200°C. The horizontal side 541 and the vertical side 542 of the fastening angle strip 504 are precisely designed to ensure perfect matching with the fastening area and the flip area 534 of the housing 1, and its soft characteristics enable the fastening angle strip 504 to pass through various areas smoothly, which is mainly reflected in the vertical side 542 of the fastening angle strip 504 being bent in the flip area 534 until the second fastening area 532 is filled, and finally the circuit board 3 and the housing 1 are tightly connected.

[0070] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0071] The above description is only used to illustrate the technical solution of the present invention rather than to limit it. Other modifications or equivalent substitutions made to the technical solution of the present invention by ordinary technicians in this field should be included in the scope of the claims of the present invention as long as they do not depart from the spirit and scope of the technical solution of the present invention.

Claims

1. A miniaturized SMD crystal oscillator, comprising a housing, a quartz crystal and a circuit board, wherein the quartz crystal is electrically connected to the circuit board, characterized in that: A cavity is provided at the bottom of the shell, a heat transfer plate is provided in the cavity extending downward, a heat dissipation groove is formed between the heat transfer plate and the shell, a first heat transfer hole is provided on the left side of the heat transfer plate, and a second heat transfer hole is provided on the right side of the heat transfer plate. The circuit board is mounted on the bottom of the shell through fasteners, and the circuit board has a plurality of pins.

2. A miniaturized SMD crystal oscillator according to claim 1, characterized in that: The number of the pins is 4, which are divided into a1 a2 a3 a4. The a1 and a3 are L-shaped pins arranged diagonally, and the a2 and a4 are rectangular pins arranged symmetrically.

3. A miniaturized SMD crystal oscillator according to claim 2, characterized in that: The a1 and a3 are empty pins.

4. A miniaturized SMD crystal oscillator according to claim 1, characterized in that: A cold contact block is provided on the top of the inner wall of the housing and extends downwards. The indented shape of the cold contact block is consistent with the outer shape of the quartz crystal.

5. A miniaturized SMD crystal oscillator according to claim 4, characterized in that: The cold contact block is made of ceramic and is integrally formed with the shell.

6. A miniaturized SMD crystal oscillator according to claim 1, characterized in that: The size of the circuit board is larger than that of the housing, and the heat transfer plate is on the same horizontal line as the lowest point of the housing.

7. A miniaturized SMD crystal oscillator according to claim 1, characterized in that: The first heat transfer hole, the second heat transfer hole and the heat dissipation slot are interconnected.

8. A miniaturized SMD crystal oscillator according to claim 1, characterized in that: The fastener comprises: Expansion compartments are symmetrically provided on the front and back sides of the bottom of the circuit board, fastening openings are opened at the positions of the expansion compartments on the circuit board, and angle plates are provided inside the fastening openings, and are divided into 4 areas by the angle plates, namely, a first fastening area, a second fastening area, a third fastening area and a flipping area, and fastening angle strips are symmetrically provided on the front and back sides of the bottom of the shell, and the fastening angle strips are divided into horizontal sides and vertical sides.

9. A miniaturized SMD crystal oscillator according to claim 8, characterized in that: The fastening corner strip is made of fluororubber.

10. A miniaturized SMD crystal oscillator according to claim 5, characterized in that: The space between the quartz crystal and the cold contact block is filled with thermal conductive paste.

Images