WO2024050842A1 - 一种封装结构和电子设备 - Google Patents

一种封装结构和电子设备 Download PDF

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Publication number
WO2024050842A1
WO2024050842A1 PCT/CN2022/118259 CN2022118259W WO2024050842A1 WO 2024050842 A1 WO2024050842 A1 WO 2024050842A1 CN 2022118259 W CN2022118259 W CN 2022118259W WO 2024050842 A1 WO2024050842 A1 WO 2024050842A1
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WIPO (PCT)
Prior art keywords
soldering
packaging structure
temperature
crystal oscillator
structure according
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PCT/CN2022/118259
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English (en)
French (fr)
Inventor
拓勇
龚涛
张佳亮
成夏彤
赵飞龙
查锋涛
孙利国
Original Assignee
华为技术有限公司
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Priority to PCT/CN2022/118259 priority Critical patent/WO2024050842A1/zh
Publication of WO2024050842A1 publication Critical patent/WO2024050842A1/zh

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/02—Details
    • H03B5/04—Modifications of generator to compensate for variations in physical values, e.g. power supply, load, temperature
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03B—GENERATION OF OSCILLATIONS, DIRECTLY OR BY FREQUENCY-CHANGING, BY CIRCUITS EMPLOYING ACTIVE ELEMENTS WHICH OPERATE IN A NON-SWITCHING MANNER; GENERATION OF NOISE BY SUCH CIRCUITS
    • H03B5/00—Generation of oscillations using amplifier with regenerative feedback from output to input
    • H03B5/30—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator
    • H03B5/32—Generation of oscillations using amplifier with regenerative feedback from output to input with frequency-determining element being electromechanical resonator being a piezoelectric resonator

Definitions

  • the present application relates to the field of electronic technology, and specifically to a packaging structure and electronic equipment.
  • the operating status of some circuits or electronic equipment will be affected by temperature. Changes in temperature cause abnormal output signals of these circuits or electronic equipment. For example, the operation of devices such as crystal oscillators and voltage-controlled oscillators is greatly affected by temperature.
  • crystal oscillators as an example, in Wireless communication equipment or other electronic equipment requires an oscillation source to generate an oscillation signal to ensure normal work or operation.
  • wireless communication equipment requires a local oscillator source to up-convert analog signals to radio frequency or microwave frequency bands, and the local oscillator source usually uses a crystal. Or the crystal oscillator is used as a reference source. The quality of the reference source largely determines the quality of the local oscillator source, which in turn will have a greater impact on the quality of wireless communication signals.
  • the working environment temperature of the product is not constant. As the ambient temperature changes, the working characteristics of the crystal or crystal oscillator will also change. The two most important problems are the temperature drift of the crystal. And crystal frequency hopping caused by temperature changes due to coefficient of thermal expansion (CTE) mismatch. Temperature drift means that temperature changes will cause the operating frequency of the crystal or crystal oscillator to change, resulting in frequency hopping, resulting in abnormal output frequency, and may even cause equipment crash or system disorder.
  • CTE coefficient of thermal expansion
  • temperature compensation methods are usually used to improve the problem that the operating status of the above-mentioned circuits or electronic equipment is affected by temperature.
  • electric heating sheets are used to heat the circuit packages to maintain a constant temperature.
  • such solutions usually consume high power and are costly. larger.
  • Embodiments of the present application provide a packaging structure and electronic equipment to improve the existing temperature compensation scheme's problems of high power consumption and high cost.
  • embodiments of the present application provide a packaging structure, including: an internal circuit, and a packaging shell that encapsulates the internal circuit; the packaging shell has a first surface, the first surface includes a plurality of solder pins, and the first surface also includes The heating layer includes a circuit connected between the first soldering pin and the second soldering pin on the first surface.
  • a heating layer is provided on the packaging shell.
  • the heating layer contains circuits for heating, and the circuits are connected to the first soldering feet and the second soldering feet provided on the first surface of the packaging shell. Therefore, by inputting electrical signals to the first solder pin and the second solder pin, the circuit can generate heat to heat the entire package structure.
  • a heat-conducting medium such as air or heat-conducting liquid, etc.
  • the circuit includes resistive paste disposed on the first surface.
  • resistive paste instead of other heating devices can reduce process difficulty and reduce preparation costs.
  • the lines are evenly distributed on the first surface.
  • the even distribution of the circuits on the first surface can better uniformly heat the entire package structure.
  • the lines are distributed in a serpentine shape on the first surface.
  • the serpentine distribution design makes heat conduction more efficient, allowing the temperature of the entire packaging structure to rise faster and to be heated more evenly.
  • the internal circuit includes a crystal oscillator, a third solder pin and a fourth solder pin are provided on the first surface, the first pole of the crystal oscillator is connected to the third solder pin, and the second pole of the crystal oscillator is connected to the fourth solder pin.
  • Solder pin connection the crystal oscillator has a temperature drift phenomenon. When the operating temperature changes, the signal frequency output by the crystal oscillator will also change.
  • the heating layer can heat the entire package structure (including the internal crystal oscillator), which can make the crystal oscillator and the package shell and solder pins The temperature can be kept relatively constant, which can improve the problem of changes in the operating frequency of the crystal oscillator due to environmental changes.
  • the distance between the welding surface of the plurality of welding legs on the first surface and the first surface is greater than the thickness of the heating layer.
  • the resistive slurry includes nichrome.
  • Nickel-chromium alloy has low cost and good heating efficiency.
  • the first solder pin and the second solder pin reuse solder pins without electrical characteristics on the packaging structure. Soldering feet without electrical characteristics on the reused package structure will not affect the normal operation of the internal circuit.
  • the first solder pin and the second solder pin reuse an empty solder pin or a ground solder pin on the packaging structure.
  • the grounded solder legs and empty solder legs are used to apply voltage to the heating layer to achieve heating. These solder legs themselves have no electrical characteristics and do not affect the normal function of the internal circuit.
  • the material of the packaging shell includes ceramic material or resin material. Ceramic materials and resin materials have high thermal conductivity and good thermal conductivity, and can evenly heat the soldering pins and the crystal oscillator in the package, so that the internal circuit can work at a relatively stable temperature.
  • the first surface is rectangular, the first welding leg and the second welding leg are distributed at both ends of a diagonal line of the first surface; the third welding leg and the fourth welding leg are distributed on the first surface. The ends of another diagonal line from one surface.
  • inventions of the present application also provide an electronic device.
  • the electronic device includes a printed circuit board and a packaging structure, and the packaging structure is connected to the printed circuit board.
  • the distance between the first surface and the printed circuit board is greater than the thickness of the heating layer.
  • Figure 1 shows a schematic diagram of a radio frequency transmitter architecture provided by an embodiment of the present application
  • Figure 2 shows a schematic diagram of a radio frequency receiver architecture provided by an embodiment of the present application
  • Figure 3 shows a crystal temperature drift diagram provided by an embodiment of the present application
  • Figure 4 shows a schematic diagram of a packaging structure provided by an embodiment of the present application
  • Figure 5 shows a schematic diagram of a constant temperature crystal oscillator provided by an embodiment of the present application
  • Figure 6 shows a schematic diagram of temperature drift of a constant-temperature crystal oscillator provided by an embodiment of the present application
  • Figure 7 shows a schematic diagram of another constant temperature crystal oscillator provided by an embodiment of the present application.
  • Figure 8 shows a schematic diagram of a packaging structure provided by an embodiment of the present application.
  • Figure 9 shows a schematic diagram of another packaging structure provided by an embodiment of the present application.
  • Figure 10 shows a schematic diagram of the heating effect of the packaging structure provided by the embodiment of the present application.
  • first”, “second”, etc. are used for descriptive purposes only and shall not be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Thus, features defined by “first,” “second,” etc. may explicitly or implicitly include one or more of such features.
  • connection should be understood in a broad sense.
  • connection can be a fixed connection, a detachable connection, or an integral body; it can be a direct connection or a detachable connection. Can be connected indirectly through intermediaries.
  • the operating status of some circuits or electronic equipment is greatly affected by temperature, such as crystal oscillators, voltage-controlled oscillators, etc.
  • temperature such as crystal oscillators, voltage-controlled oscillators, etc.
  • a local oscillator source is needed to upconvert analog signals to the radio frequency or microwave frequency band.
  • the function of the local oscillator source is to generate a local oscillator frequency, which will fluctuate within a certain range.
  • a reference source is set in the local oscillator circuit.
  • the reference source frequency is relatively stable.
  • There is a feedback mechanism in the local oscillator circuit responsible for stabilizing the local oscillator frequency. Partial sampling of the local oscillator signal is compared with the reference source. If the frequency of the local oscillator source is lower, it will be compensated. If the local oscillator signal is lower, it will be compensated. If the frequency of the vibration source is higher, it will be eliminated. Therefore the frequency stability of the reference source is crucial.
  • the most commonly used implementation of the reference source is a crystal oscillator.
  • the crystal oscillator is an oscillator made by using the piezoelectric effect of quartz crystal.
  • a thin slice is cut from a quartz crystal at a certain azimuth angle, and silver layers are coated on its two corresponding surfaces as electrodes. Connect a wire to the solder pin, and the package forms a simple quartz crystal oscillator, referred to as a crystal oscillator.
  • the crystal oscillator provided by the embodiment of the present application can be applied in a wireless communication system, for example, in a radio frequency transmitter or radio frequency receiver.
  • the radio frequency transmitter architecture includes: digital-to-analog converter 001, filter 002, modulator 003, radio frequency amplifier 004, amplifier 005, filter 006 and local oscillator source 007.
  • the output end of the digital-to-analog converter 001 is connected to the input end of the filter 002, the output end of the filter 002 is connected to the input end of the modulator 003, the output end of the modulator 003 is connected to the input end of the radio frequency amplifier 004, and the output end of the radio frequency amplifier 004 Connect to the antenna through amplifier 005 and filter 006.
  • the digital-to-analog converter 001 converts the digital signal into an analog signal
  • the filter 002 reconstructs the pre-sampling signal according to the sampling points.
  • the local oscillator source 007 is connected to the modulator 003.
  • the local oscillator source 007 generates a clock signal through an oscillator circuit and outputs it to the modulator 003.
  • the local oscillator source 007 uses a crystal oscillator as a reference source to generate a clock signal.
  • the modulator 003 combines the local oscillator source and the filter.
  • the signal provided by the amplifier 002 is modulated into a stable high-frequency signal, and then passes through the radio frequency amplifier 004 and the amplifier 005 for power amplification.
  • the amplified signal is filtered by the filter 006 to filter the harmonics in the local oscillator source 007 and the modulator 003, thereby obtaining a specific frequency signal, which is transmitted through the antenna.
  • the role of the crystal oscillator in the radio frequency transmitter is to provide a stable oscillation signal.
  • the crystal oscillator is also required to provide such a stable oscillation signal.
  • the radio frequency receiver architecture includes: a local oscillator source 100, a low noise amplifier 101, a mixer 102, an intermediate frequency amplifier 103, a filter 104 and an analog-to-digital converter 105.
  • the receiving antenna is connected to the input end of the low-noise amplifier 101, the output end of the low-noise amplifier 101 is connected to the input end of the mixer 102, the output end of the mixer 102 is connected to the input end of the intermediate frequency amplifier 103, and the output end of the intermediate frequency amplifier 103 is connected to the filter
  • the input terminal of the filter 104 is connected to the analog-to-digital converter 105 and the output terminal of the filter 104 is connected.
  • the signal received by the antenna is transmitted to the low-noise amplifier 101.
  • the local oscillator source 100 uses the crystal oscillator as a reference source to generate a clock signal.
  • the mixer 102 mixes the signal amplified by the low-noise amplifier 101 and the clock signal generated by the local oscillator source 100. , output an intermediate frequency signal.
  • the intermediate frequency signal is amplified by the intermediate frequency amplifier 103, and then filtered by the filter 104 to obtain a signal of a specific frequency.
  • the analog signal is converted into a digital signal by the analog-to-digital converter 105.
  • the working environment temperature of the crystal oscillator is not constant. As the ambient temperature changes, the working characteristics of the crystal oscillator will change. For example, the operating frequency of the crystal oscillator may shift, and the temperature will affect the normal operation of the crystal oscillator.
  • the output frequency accuracy has a greater impact.
  • the crystal oscillator accuracy here refers to the frequency output by the crystal oscillator when the working environment is stable at 25°C.
  • the frequency variation of the crystal is measured by the frequency jitter value (part per million, PPM).
  • PPM is one of the basic units of the crystal oscillator and represents the accuracy and relative deviation of the crystal oscillator. It is calculated in the following way: subtract the target frequency from the actual frequency and divide it by the target frequency, and move the decimal point backward by 6 digits to get the PPM value. For example, if the nominal frequency is 10MHz, the actual operating frequency of the crystal is 10Mhz+10Hz, and the deviation from the nominal frequency is 10Hz, then the deviation is exactly 1PPM.
  • the crystal itself has temperature drift characteristics, which means that the frequency of the crystal will change with the change of the operating temperature during the vibration process, so the PPM of the crystal will change with the temperature change.
  • thermal shock that is, rapid heating or cooling
  • the frequency of the crystal oscillator will drift.
  • the crystal oscillator may not vibrate.
  • Electronic frequency components made of quartz crystals all have certain temperature drift characteristics.
  • Figure 3 shows a schematic diagram of the temperature drift curve of the crystal. From Figure 3, we can see that the frequency that adapts to the crystal oscillation starts from -40°C. As the temperature increases, the frequency is constantly changing. , this change is called temperature drift. Different types of crystals have temperature drift characteristics, and the trajectory of temperature drift changes in an S-shaped curve.
  • the peak-to-peak change in the figure exceeds 50PPM, which means that when the temperature changes greatly, the frequency change of the crystal also changes greatly.
  • the temperature drift characteristics of the crystal will lead to unstable frequency changes.
  • Crystals are usually used as a reference source in electronic equipment.
  • the frequency instability of the reference source will further cause the frequency of the local oscillator source to change.
  • the range of unstable fluctuations expands. For example, if the frequency of the local oscillator source in a wireless communication system is unstable, it may eventually lead to poor communication signal quality.
  • FIG 4 shows a schematic diagram of a crystal oscillator package, including a crystal oscillator 200 and a packaging shell 205.
  • the packaging shell 205 is provided with input solder pins 201, ground solder pins 202, output solder pins 203 and ground solder pins 204.
  • the ground solder pin 202 and the ground solder pin 204 have no electrical characteristics, and setting these two solder pins can increase the firmness of the package structure when being welded to the printed circuit board.
  • the input soldering pin 201 and the output soldering pin 202 are the soldering pins connecting two electrodes of the crystal oscillator.
  • the input soldering pin 201 is connected to one electrode of the crystal oscillator through a connecting wire, and the output soldering pin 202 is connected to the other electrode of the crystal oscillator through a connecting wire.
  • Soldering the package to the printed circuit board may cause a coefficient of thermal expansion (CTE) mismatch.
  • CTE is the expansion and contraction of an object due to temperature changes, which reflects the change in length caused by a unit temperature change.
  • Different materials have different thermal expansion coefficients. When the temperature changes (for example, the temperature rises), different materials may expand and contract differently. This will cause stress between different materials, and the stress will be released when it accumulates to a certain extent. It may cause the aforementioned materials to deform.
  • the soldering feet of the package structure may undergo instantaneous slight deformation or displacement. This deformation or displacement will cause the phase of the signal output by the crystal oscillator to change. Instantaneous mutation, that is, phase jump.
  • the temperature of the working environment of the crystal is unstable, the temperature drift characteristics of the crystal and the adaptation of the thermal expansion coefficient may cause frequency or phase hopping of the signal output by the crystal oscillator, which may cause abnormal operation of electronic equipment.
  • Such crystal oscillators can be called oven controlled crystal oscillators (OXCO).
  • OXCO oven controlled crystal oscillators
  • the influence of temperature drift will be minimized. Since in practical applications, it is easier to heat the crystal oscillator than to cool the crystal oscillator, so the general constant-temperature crystal oscillator is achieved by heating the crystal oscillator to a certain temperature.
  • Figure 5 shows a schematic diagram of a constant temperature crystal oscillator.
  • the constant temperature crystal oscillator shown in Figure 5 uses a constant temperature bath to heat the crystal oscillator to maintain a constant temperature.
  • the constant temperature crystal oscillator includes a constant temperature bath, a constant temperature bath controller, a heating circuit, a temperature sensor and a crystal oscillator.
  • the crystal is placed in a constant temperature bath.
  • a heating circuit and a temperature sensor are provided in the constant temperature bath.
  • the heating circuit and temperature sensor are connected to the constant temperature bath controller.
  • the constant temperature bath controller can control the heating circuit to heat the constant temperature bath, and at the same time the temperature sensor detects the temperature in the constant temperature bath.
  • the constant temperature bath controller adjusts the heating circuit according to the temperature detected by the temperature sensor to keep the temperature in the constant temperature bath constant. This is used to avoid temperature drift of the crystal oscillator and improve the frequency characteristics of the crystal oscillator.
  • FIG. 6 shows the frequency change of the crystal oscillator when the constant temperature bath is heated from -45°C to 100°C. It can be seen that the amplitude of the S-shaped curve of temperature drift decreases, indicating that the impact of the temperature drift characteristics of the crystal oscillator on frequency stability is reduced after using the constant temperature crystal oscillator technology solution.
  • the thermostatic bath technology takes 5-10 minutes from startup to heating to stable operation, during which it will experience a preheating time.
  • the warm-up time refers to the time required for the crystal oscillator to operate stably at the specified frequency value from initial power-on.
  • the warm-up time of OCXO is generally up to 5 minutes.
  • the power consumption required for the warm-up time before the OCXO is powered on and reaches the specified temperature range is relatively large.
  • the constant temperature bath solution has high cost and large components. Due to the preheating time, the power consumption is also large. Although it can well improve the temperature drift problem of the crystal, components such as heating circuits may introduce additional noise and phase noise. It will cause the frequency to lead or lag, and the instantaneous stability of the frequency will be affected, which will ultimately affect the accuracy of information transmission.
  • Figure 7 shows another solution of a constant temperature crystal oscillator provided by an embodiment of the present application.
  • the constant temperature crystal oscillator provided by an embodiment of the present application includes: a crystal oscillator 400, a ceramic base 401, a heating tube 402 and a printed circuit board. Circuit Board 403.
  • the crystal oscillator 400 is installed on a ceramic base 401.
  • the ceramic base 401 is installed on one surface of the printed circuit board 403.
  • a heating tube 402 is provided on the other surface of the printed circuit board 403.
  • the heat generated by the heating tube 402 is constant for the crystal oscillator. temperature to achieve the effect of reducing temperature drift and improving frequency hopping.
  • the ceramic base and the heating tube are respectively arranged on both sides of the printed circuit board 403.
  • the printed circuit board 403 between the ceramic base and the heating tube 402 is hollowed out, so that better The thermal conductivity effect can effectively improve the temperature drift problem of the crystal 400.
  • the solder pin temperature needs to be raised to above 10°C. Due to the setting of the heating tube 402 and the ceramic base 401 On both sides of the printed circuit board, the crystal oscillator is located above the ceramic base 401.
  • the heat of the heating tube 402 cannot directly act on the crystal oscillator and requires a heat transfer process. During the heat transfer process, thermal radiation loss will inevitably occur, so such a heating solution consumes high power.
  • embodiments of the present application provide a packaging structure.
  • the heat-generating layer can heat the entire packaging structure.
  • a heat-conducting medium such as air or thermal conductivity
  • the heat conduction efficiency is higher, so power consumption can be reduced.
  • a packaging structure 500 provided by an embodiment of the present application is shown in Figure 8 and includes: an internal circuit 510, a packaging shell 540 for packaging the internal circuit 510, and a heating layer 530.
  • the packaging shell 540 has a first surface 520.
  • a plurality of soldering feet are provided, and some of the soldering feet are connected to the internal circuit 510.
  • the internal circuit 510 receives signals from the external circuit through this part of the soldering feet, or outputs signals to the external circuit.
  • Another part of the soldering feet are soldering feet without electrical characteristics, such as empty soldering feet, grounding soldering feet, etc. provided to increase welding stability when the package structure 500 is soldered to a printed circuit board.
  • the first surface 520 is provided with a first soldering leg 521 and a second soldering leg 522.
  • the heating layer 505 is provided on the first surface 520.
  • the heating layer 505 includes the first soldering leg 521 and the second soldering leg 522 connected to the first surface 520. The line between the two solder legs 522.
  • the circuit here can be formed by resistive paste, for example, the circuit of the heating layer 530 formed by coating the resistive paste on a preset area on the first surface 520.
  • the circuits of the layer 530 form a loop, the circuits of the heating layer 530 can heat the entire package structure 500 so that the internal circuit 510 can be maintained at a relatively stable operating temperature and avoid changes in the operating characteristics of the internal circuit 510 due to temperature changes.
  • the first solder pin 521 and the second solder pin 522 reuse solder pins that do not have electrical characteristics on the packaging structure 500.
  • they can be empty solder pins or grounding solder pins. Setting some empty solder pins on the packaging structure 500 can enhance The stability of the package structure welded on the printed circuit board, and the embodiment of the present application utilizes these solder pins without electrical characteristics, and uses these solder pins without electrical characteristics to energize the circuits of the heating layer 530, thereby energizing the package. Structure 500 integrally heated.
  • the circuits of the heating layer 530 are formed by coating resistive paste in a preset area on the first surface 520.
  • the circuits of the heating layer 530 are in The resistive slurry is evenly distributed on the first surface 520 , in other words, the resistive slurry is evenly coated on the preset area on the first surface 520 to form evenly distributed lines.
  • a resistive paste may be coated on the serpentine-shaped area on the first surface 520 to form serpentine-shaped distribution lines.
  • the circuits of the heating layer 530 can generate heat, and the heating layer 530 is disposed on the first surface 530 of the packaging structure 500.
  • the crystal oscillator 510 in the package shell 540 and each solder pin (such as the first solder pin 521 and the second solder pin 522) on the package shell 540 can be heated directly without passing through the heat conduction medium.
  • the heat conduction efficiency is higher, so the power consumption can be reduced. This enables a low-cost, low-power constant-temperature crystal oscillator solution.
  • the circuits of the heating layer 530 can also have other shapes. For example, it can be spiral, ring, etc.
  • the distance from the welding surface of each solder leg on the first surface 520 to the first surface 520 is greater than the thickness of the heating layer.
  • the above-mentioned welding surface of the first solder leg 521 , the welding surface of the second solder leg 522 and the first surface 520 are different from each other.
  • the distance between one surface 540 is greater than the thickness of the heating layer 530, so that when the package structure 500 provided by the embodiment of the present application is welded to the printed circuit board, the resistor paste will not contact the printed circuit board, and short circuit can be avoided.
  • resistance paste is more efficient, environmentally friendly, energy-saving, lower cost, and simpler in preparation process than traditional resistance wires and electric heating tubes.
  • the resistance slurry includes nickel-chromium alloy, which has low cost and good heating efficiency.
  • the heating circuit formed by the resistance paste is connected to the first solder leg 521 and the second solder leg 522, so after the first solder leg 521 and the second solder leg 522 are powered on to form a circuit with the circuit of the heating layer 530, the resistance paste It will generate heat, so that the heating layer 530 can quickly heat the package shell 540 and the crystal oscillator 510 inside. Unnecessary thermal radiation loss is reduced during the heat transfer process, making it more efficient, and because no additional active devices are introduced, no additional phase noise is caused.
  • the first surface 520 is rectangular, and the first soldering feet 521 and the second soldering feet 522 are distributed on the first surface. At both ends of a diagonal line of the first surface 520, the first solder pin 521 and the second solder pin 522 are distributed at both ends of the other diagonal line of the first surface 520.
  • This solder pin distribution method can improve the soldering of the package structure 500. Stability when printed on the printed circuit board.
  • the serpentine lines can have more circuitous or bent shapes, the contact area with the first surface 520 is larger, and the distribution is more uniform, which has a greater impact on the packaging structure 500 The heating efficiency will be higher and faster heating can be achieved.
  • the first surface 520 is rectangular, and the first soldering feet 521 and the second soldering feet 522 are also They may be distributed on one side of the first surface 520 (instead of both ends of the diagonal), and the first soldering feet 521 and the second soldering feet 522 are distributed on the other side of the first surface 520, as shown in FIG. 9 .
  • the first end of the circuit of the heating layer 530 is electrically connected to the first soldering leg 521
  • the second end is electrically connected to the second soldering leg 522 .
  • the first surface of the packaging shell 540 is rectangular, but it is not limited to this. It can also be in other shapes, such as circular, oval, etc.
  • the circuit of the heating layer 530 is in The first welding leg 521 and the second welding leg 522 are evenly distributed on the surface, such as a serpentine distribution.
  • the serpentine distribution can enhance the heating efficiency and make the heat transfer more uniform, or the lines of the heating layer 530 can be distributed in other ways. way, such as spiral, circular or ring, etc.
  • the above-mentioned packaging shell 540 can be made of ceramic material or resin.
  • the ceramic material has a high thermal conductivity to improve the heating efficiency of the packaging structure 500 and the internal circuit 510.
  • the packaging shell 540 can also be made of other packaging materials with good thermal conductivity.
  • the first soldering pin 521 and the second soldering pin 522 can be connected to the voltage output port of the controller through the wires on the printed circuit board, so that the controller can adjust the The voltage output by the voltage output port controls the heating of the heating layer 530 .
  • a temperature sensor can also be provided inside or outside the packaging structure 500.
  • the temperature sensor is used to detect the temperature of the packaging structure 500.
  • the temperature sensor can be connected to the controller to send the temperature to the controller, and the controller adjusts the voltage according to the temperature.
  • the voltage output by the output port For example, when the temperature is lower than the preset temperature, the output voltage is increased. When the temperature is higher than the preset temperature, the output voltage is reduced so that the crystal oscillator can operate in a relatively constant temperature environment.
  • the preset temperature here is The temperature can be set according to the temperature characteristics of the crystal oscillator, for example, it can be set to 145°C.
  • the above-mentioned internal circuit 510 may include a crystal oscillator.
  • the crystal oscillator includes a first pole and a second pole.
  • a third soldering pin 523 and a fourth soldering pin 524 are also provided on the first surface 520.
  • the first pole is connected to the third solder leg 523, and the second pole is connected to the fourth solder leg 524.
  • the third solder leg 523 and the fourth solder leg 524 can be used to connect a power signal or output an oscillation signal.
  • the packaging structure provided by the embodiment of the present application can be used to heat the crystal oscillator and each solder pin.
  • the crystal oscillator can be maintained at a relatively stable operating temperature and avoid problems such as frequency hopping due to temperature drift.
  • the heating layer 530 of the packaging structure 500 provided by the embodiment of the present application (without passing through the thermal conductive medium) is disposed on the first surface 520 The entire package structure 500 is heated. Compared with the traditional solution that requires heating the package structure through a heat conduction medium (such as air or heat conduction liquid, etc.), the heat conduction efficiency is higher, so power consumption can be reduced.
  • Figure 10 shows a schematic diagram of the heating effect provided by the embodiment of the present application.
  • the circuits of the heating layer 530 generate heat after being powered on, and the temperature is the highest.
  • the heat is conducted through the package shell 540 made of ceramic material, which can heat the internal circuit 510 and each solder pin on the package structure 500, such as the first solder pin 521, the second solder pin 522, and the third solder pin 523.
  • the first solder leg 521, the second solder leg 522, the third solder leg 523 and the fourth solder leg 524 are close to the temperature of the package shell 540. It is precisely because of the high thermal conductivity of the ceramic material.
  • the circuits of the heating layer 530 evenly distributed on the first surface 520 of 2mm ⁇ 3mm only require 8mW.
  • the power consumption of about 100% can meet the demand for overall heating of the packaging structure 500 .
  • the heat-generating layer 530 is located on the surface of the package shell 540 and the heat-generating layer 530 includes a circuit connected between the first solder foot 521 and the second solder foot 522 , the circuit can be formed by resistance paste, and can be formed by attaching the first solder foot 521 to The voltage adjustment with the second welding leg 522 realizes the adjustment of the heat generation. Under normal circumstances, it is easier to heat materials to a certain temperature, but it is difficult to achieve the same degree of cooling effect. Therefore, the constant temperature point of the constant temperature crystal oscillator is generally set higher, which facilitates stable control of the constant temperature crystal oscillator. Temperature, for example, in the embodiment of the present application, the constant temperature point can be set to 145°C.
  • the packaging structure provided by the embodiment of the present application is introduced by taking the internal circuit 510 including a crystal oscillator as an example.
  • the above-mentioned internal circuit can also be other temperature-sensitive circuits.
  • voltage controlled oscillators or other temperature-sensitive circuits or electronic devices can also be other temperature-sensitive circuits.
  • inventions of the present application also provide an electronic device.
  • the electronic device includes a printed circuit board and a packaging structure of the above embodiment.
  • the packaging structure is connected to the printed circuit board.
  • the packaging structure can be welded to the printed circuit board.
  • the packaging structure includes a first surface. The first surface is provided with first soldering pins, second soldering pins, third soldering pins, and fourth soldering pins. When the packaging structure is welded on the printed circuit board, the first surface and The distance between printed circuit boards is greater than the thickness of the heating layer.
  • the electronic device also includes a controller.
  • the controller is arranged on the printed circuit board.
  • the voltage output port of the controller is connected to the third solder pin and the fourth solder pin through wires on the circuit board, and forms a loop with the circuit of the heating layer 530. Adjust the heating of the heating layer by adjusting the voltage output to the third soldering pin or the fourth soldering pin.

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  • Oscillators With Electromechanical Resonators (AREA)

Abstract

本申请提供了一种封装结构和电子设备，包括内部电路和封装内部电路的封装外壳，封装外壳包括第一表面，第一表面上设置有发热层，发热层包括连接在第一表面上第一焊脚与第二焊脚之间的线路，其中内部电路为对温度敏感的电路，温度变化可能会影响内部电路的工作状态，对第一焊脚和第二焊脚上电施加电压后发热层的线路可以发热，从而对封装结构加热，减小内部电路的工作环境的温度变化，改善内部电路的温度特性。由于发热层不经过其他的导热介质，而是设置在封装外壳的第一表面上，这样热传递效率较高，发热层所需的功耗更低。

Description

一种封装结构和电子设备 技术领域
本申请涉及电子技术领域，具体涉及一种封装结构和电子设备。
背景技术
部分电路或电子设备的运行状态会受到温度的影响，温度的变化导致这些电路或者电子状态输出信号异常，例如晶振、压控振荡器等器件的运行受温度影响较大，以晶振为例，在无线通信设备或者其他的电子设备中需要振荡源产生振荡信号以保障正常工作或运行，例如无线通信设备中需要一个本振源将模拟信号上变频到射频或者微波频段，而本振源通常采用晶体或者晶振作为参考源，参考源的质量很大程度决定了本振源的质量，进而也会对无线通信信号的质量产生较大的影响。
对于无线通信系统来说，产品的工作环境温度并不是恒定不变的，而随着环境温度的变化，晶体或晶振的工作特性也会发生改变，其中最主要的两个问题就是晶体的温飘和由于热膨胀系数(coefficient of thermal expansion，CTE)失配，在温度变化中会引起的晶体跳频。温飘是指温度变化会导致晶体或晶振的工作频率发生变化，产生跳频，导致输出频率的异常，甚至可能会造成设备的死机或系统紊乱。
目前通常使用温度补偿的方法来改善上述电路或电子设备的运行状态会受到温度的影响的问题，例如利用电热片对电路的封装加热保持恒温，但这样的解决方案通常功耗较高，成本也较大。
发明内容
本申请实施例提供一种封装结构和电子设备，用以改善现有的温度补偿方案功耗较高，成本较大的问题。
为达到上述目的，本申请实施例采用如下技术方案：
第一方面，本申请实施例提供了一种封装结构，包括：内部电路、封装内部电路的封装外壳；封装外壳具有第一表面，第一表面上包括多个焊脚，第一表面上还包括发热层，发热层包括连接于第一表面上的第一焊脚与第二焊脚之间的线路。本申请实施例提供的方案，封装外壳上设置有发热层，其中由于发热层中包含用于加热的线路，并且线路连接于封装外壳设置于第一表面上的第一焊脚和第二焊脚之间，因此可以通过对第一焊脚和第二焊脚输入电信号使得线路发热对封装结构整体进行加热，与传统的方案需要通过导热介质(例如空气或者导热液体等)对封装结构进行加热相比，导热效率更高，因此可以降低功耗。
在一种可能的实施方式中，线路包括设置在第一表面的电阻浆料。利用电阻浆料而不是其它的发热器件可以降低工艺难度，降低制备成本。
在一种可能的实施方式中，线路在第一表面上均匀分布。线路在第一表面上均匀分布可以较好地对封装结构整体均匀加热。
在一种可能的实施方式中，线路在第一表面上蛇形分布。蛇形分布的设计使得热传导效率更高，能够使封装结构整体的温度较快的上升，并且受热更加均匀。
在一种可能的实施方式中，内部电路包括晶振，第一表面上设置有第三焊脚与第四焊脚，晶振的第一极与第三焊脚连接，晶振的第二极与第四焊脚连接，晶振存在温飘现象，当工作温度发生变化时晶振输出的信号频率也会发生变化，发热层可以对整个封装结构(包括内部的晶振)加热，能够使晶振与封装外壳、焊脚等的温度可以保持相对恒定，能够改善因为环境变化而导致晶振的工作频率发生变化的问题。
在一种可能的实施方式中，第一表面上的多个焊脚的焊接面与第一表面的距离大于发热层的厚度。这样在将封装结构焊接到印制电路板上时发热层不会接触到印制电路板，能够防止发热层与印制电路板接触，防止短路，从而不影响封装结构在印制电路板上的焊接。
在一种可能的实施方式中，电阻浆料包括镍铬合金。镍铬合金成本较低的同时具有良好的发热效率。
在一种可能的实施方式中，第一焊脚、第二焊脚复用封装结构上的无电气特性的焊脚。复用封装结构上的无电气特性的焊脚不会影响内部电路的正常工作。
在一种可能的实施方式中，第一焊脚、第二焊脚复用封装结构上的空焊脚或接地焊脚。利用接地焊脚与空焊脚对发热层施加电压实现加热，这些焊脚本身并无电气特性，不影响内部电路的正常功能。
在一种可能的实施方式中，封装外壳的材料包括陶瓷材料或树脂材料。陶瓷材料和树脂材料导热系数较高，导热效果好，并能够对焊脚和封装在内的晶振均匀加热，使内部电路可以工作在较为稳定的温度状态下。
在一种可能的实施方式中，第一表面为矩形，第一焊脚与第二焊脚分布在第一表面的一条对角线的两端；第三焊脚与第四焊脚分布在第一表面的另一条对角线的两端。
第二方面，本申请实施例还提供了一种电子设备。电子设备包括印制电路板以及封装结构，封装结构与印制电路板连接。
在一种可能的实施方式中，第一表面与印制电路板之间的距离大于发热层的厚度。
其中，第二方面及其任一种实施方式所带来的技术效果可参见第一方面中不同实施方式所带来的技术效果，此处不再赘述。
附图说明
图1所示为本申请实施例提供的一种射频发射机架构示意图；
图2所示为本申请实施例提供的一种射频接收机架构示意图；
图3所示为本申请实施例提供的一种晶体温飘图；
图4所示为本申请实施例提供的一种封装结构的示意图；
图5所示为本申请实施例提供的一种恒温晶振示意图；
图6所示为本申请实施例提供的恒温晶振温飘示意图；
图7所示为本申请实施例提供的另一种恒温晶振示意图；
图8所示为本申请实施例提供的一种封装结构示意图；
图9所示为本申请实施例提供的另一种封装结构示意图；
图10所示为本申请实施例提供的封装结构发热效果示意图。
具体实施方式
下面将结合本申请实施例中的附图，对本申请实施例中的技术方案进行描述，显然，所描述的实施例仅仅是本申请一部分实施例，而不是全部的实施例。
以下，术语“第一”、“第二”等仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”等的特征可以明示或者隐含地包括一个或者更多个该特征。
此外，本申请中，“上”、“下”、“左”、“右”、“水平”以及“竖直”等方位术语是相对于附图中的部件示意置放的方位来定义的，应当理解到，这些方向性术语是相对的概念，它们用于相对于的描述和澄清，其可以根据附图中部件所放置的方位的变化而相应地发生变化。
在本申请中，除非另有明确的规定和限定，术语“连接”应做广义理解，例如，“连接”可以是固定连接，也可以是可拆卸连接，或成一体；可以是直接相连，也可以通过中间媒介间接相连。
部分电路或电子设备的运行状态受温度影响较大，例如晶振、压控振荡器等。在工作环境温度变化较大的情况下，这些电路的输出信号会与理想状态有较大的偏差。
例如，在无线通信系统中需要一个本振源将模拟信号上变频到射频或者微波频段。本振源的作用是产生一个本振频率，本振频率会在一定范围内波动。为了减小本振源不稳定性对本振频率的影响，在本振电路会设置参考源。参考源频率较为稳定，在本振电路中会有一套反馈机制负责稳定本振频率，对本振信号进行部分采样和参考源进行比较，若本振源的频率较低则对其进行补偿，若本振源的频率较高则对其进行消去。因此参考源的频率的稳定性至关重要。而参考源的实现方式最常用的就是晶振。
晶振是利用石英晶体的压电效应制成的一种振荡器，在一块石英晶体上按一定的方位角切下薄片，在它的两个对应面涂覆银层作为电极，在每个电极上各连接一条导线连接到焊脚上，封装即构成了简易的石英晶体振荡器，简称为晶振。
本申请实施例提供的晶振可以应用于无线通信系统中，例如应用在射频发射机或者射频接收机中。
例如图1，射频发射机架构包括：数模转换器001、滤波器002、调制器003、射频放大器004、放大器005、滤波器006和本振源007。数模转换器001的输出端连接滤波器002的输入端，滤波器002的输出端连接调制器003的输入端，调制器003的输出端连接射频放大器004的输入端，射频放大器004的输出端通过放大器005、滤波器006连接至天线。
其中，数模转换器001将数字信号转化为模拟信号，通过滤波器002根据采样点重建采样前的信号。本振源007与调制器003连接，本振源007通过振荡电路产生时钟信号输出给调制器003，通常本振源007以晶振作为参考源来产生时钟信号，调制器003将本振源和滤波器002所提供的信号调制成为稳定的高频信号，在经过射频放大器004和放大器005进行功率放大。放大后的信号经过滤波器006对本振源007和调制器003中的谐波进行过滤，从而得到特定的频率信号，通过天线发射。
晶振在射频发射机中的作用是提供稳定的振荡信号，在射频接收机中，同样需要晶振提供这样稳定的振荡信号。
例如图2，射频接收机架构包括：本振源100、低噪声放大器101、混频器102、 中频放大器103、滤波器104和模数转化器105。接收天线连接低噪声放大器101的输入端，低噪声放大器101的输出端连接混频器102的输入端，混频器102的输出端连接中频放大器103的输入端，中频放大器103的输出端连接滤波器104的输入端，滤波器104的输出端连接模数转化器105。
天线接收的信号传输至低噪声放大器101，本振源100以晶振作为参考源来产生时钟信号，混频器102将由低噪声放大器101放大过后的信号和本振源100产生的时钟信号进行混频，输出中频信号，中频信号经过中频放大器103进行信号的放大，再由滤波器104滤波得到特定频率的信号，经过模数转化器105将模拟信号转化为数字信号。
对于无线通信来说，晶振的工作环境温度并非是恒定不变的，而随着环境温度的变化，晶振的工作特性会发生变化，例如晶振的工作频率可能会发生偏移，温度对晶振正常工作时输出的频率精度影响较大，此处的晶振精度指的是晶振在工作环境稳定为25℃的条件下所输出的频率。
通常，利用百万分之的频率跳动值(part per million，PPM)来衡量晶体的频率变化大小，PPM是晶振的基本单位之一，表示晶振的精度和相对偏差。它通过以下的方式来计算：用实际的频率减目的频率再除以目的频率，且将小数点向后移动6位数即为PPM值。例如，标称频率为10MHz晶体实际工作频率为10Mhz+10Hz，与标称频率相比偏差为10Hz，那么这个偏差恰好为1PPM。
晶体本身具有温飘特性，也就是说晶体在振动过程中频率会随着工作温度的变化而变化，因此晶体的PPM会随着温度变化而变化。在热冲击即快速加温或降温的情况下，晶振频率会发生频率漂移现象，严重时可能会导致晶振不起振。使用石英晶体做成的电子频率元器件，均有一定的温飘特点。
如图3所示，图3示出了晶体的温飘曲线示意图，从图3中可以看到适应晶体振荡的频率从-40℃开始，随着温度的升高，频率也在不断地发生变化，这种变化称为温飘。不同类型的晶体均具有温飘特性，并且温飘变化的轨迹呈S型曲线。
例如，如图3示出的，在温度从-40℃变化至-15℃时，晶体的PPM从10左右增加至20，在温度从-15℃变化至65℃时，晶体的PPM从20变化至-15左右，在温度从65℃变化至125℃时，晶体的PPM从-15增加至55左右。
图中峰峰值变化超过了50PPM，意味着当温度变化较大时，晶体的频率变化量的变化也较大。而当晶体工作在温度不断变化的环境中，由于晶体的温飘特性会导致频率变化的不稳定，晶体在电子设备中通常作为参考源，参考源的频率不稳定会进一步导致本振源频率的不稳定波动范围扩大，例如，若无线通信系统中的本振源频率不稳定，最终可能会导致通信信号质量变差。
晶振在工程上常常会通过封装焊接在印制电路板上。图4示出了一种晶振的封装示意图，包括晶振200和封装外壳205，封装外壳205上设置有输入焊脚201、接地焊脚202、输出焊脚203和接地焊脚204。接地焊脚202和接地焊脚204没有电气特性，设置这两个焊脚可以增加封装结构焊接在印制电路板上的牢固性。输入焊脚201和输出焊脚202是晶振的两个电极连接焊脚，输入焊脚201通过连接线与晶振的一个电极连接，输出焊脚202通过连接线与晶振的另一个电极连接。将封装焊接在印制电路板 上可能会出现热膨胀系数(coefficient of thermal expansion，CTE)失配的现象。CTE是物体由于温度改变而出现的胀缩现象，反映了单位温度变化下所导致的长度量值的变化。不同的材料的热膨胀系数不同，在温度发生变化(例如温度升高)的情况下，不同的材料的涨缩可能不同，这样会导致在不同材料之间产生应力，应力积累到一定成都会释放，有可能会导致前述的材料发生形变。例如，当温度变化时，由于助焊剂或其他杂质与器件焊脚的热膨胀系数失配，封装结构的焊脚可能会发生瞬间的微小形变或位移，这个形变或位移会导致晶振输出的信号相位发生瞬间突变，即相跳。
由此可见，晶体的工作环境温度不稳定，晶体的温飘特性还有热膨胀系数适配等问题可能会导致晶振输出的信号发生跳频或相跳，进而可能会导致电子设备运行异常，为了解决上述问题，可以让晶体处在恒定温度下，这样的晶振可以称为恒温晶振(oven controlled crystal oscillators，OXCO)，当温度不再变化时，温飘的影响将会被减到最小。由于在实际应用中，对晶振加热升温相比令晶振降温更容易实现，因此一般的恒温晶振都是通过对晶振加热，将其加热至一定温度来实现的。
图5示出了一种恒温晶振的示意图，图5示出的恒温晶振采用恒温槽对晶振加热使其保持恒温。
恒温晶振包括恒温槽、恒温槽控制器、加热电路、温度传感器与晶振，其中将晶体置于恒温槽内，恒温槽内设置有加热电路和温度传感器，加热电路和温度传感器与恒温槽控制器连接，恒温槽控制器可以控制加热电路对恒温槽进行加热，同时温度传感器检测恒温槽内的温度，恒温槽控制器根据温度传感器检测的温度对加热电路行调节，使恒温槽内的温度维持恒定，以此来避免晶振发生温飘，改善晶振的频率特性。
将晶振置于恒温槽内部，通过设置恒温工作点，使槽体保持恒温状态。温度传感器负责对环境温度进行监控，当温度高于恒温工作点，恒温槽控制器控制加热电路会减小发热功率；当温度低于恒温工作点，加热电路会增大发热功率，使晶振维持在恒温状态。如图6所示为恒温槽从-45℃加热到100℃时晶振产生的频率变化。可以看到温飘的S形曲线幅度减小，说明晶振的温飘特性导致对频率稳定性的影响在使用恒温晶振技术方案后减小。
但是恒温槽技术从启动到加热到稳定工作需要5-10分钟，期间会经历一个预热时间。预热时间指晶振从初始上电到稳定工作在规定频率值所需要的时间。OCXO的预热时间一般最多5分钟。在OCXO上电达到指定温度范围前的预热时间所需要的功耗较大。
恒温槽解决方案成本高，器件大，由于存在预热时间的原因，功耗也较大，虽然能够很好地改善晶体的温飘问题，但是加热电路等器件可能会引入额外的噪声，相位噪声会造成频率的超前或滞后，频率的瞬时稳定性受到影响，最终会对信息传递的精准性产生影响。
图7示出了本申请实施例提供的另一种恒温晶振的方案，如图7所示，本申请实施例提供的恒温晶振，包括：晶振400，陶瓷基座401，发热管402和印制电路板403。晶振400设置在陶瓷基座401上，陶瓷基座401安装在印制电路板403的一个表面，在印制电路板403的另一个表面设置有发热管402，通过发热管402产生热量恒定晶振的温度，实现减小温度漂移和改善跳频的效果。
如图7所示，陶瓷基座和发热管分别设置在印制电路板403的两侧，将陶瓷基座和发热管402之间的印制电路板403挖空槽，这样可以实现更好的导热效果，能够有效的改善晶体400的温飘问题，但若要改善因为CTE失配而产生的相跳问题，需要将焊脚温度抬升到10℃以上，由于发热管402与陶瓷基座401设置在印制电路板的两侧，而晶振又位于陶瓷基座401的上方。发热管402的热量不能够直接作用在晶振上，需要一个热传递过程，在热传递过程中不可避免的会出现热辐射的损耗，因此这样的加热方案功耗较高。
有鉴于此，本申请实施例提供了一种封装结构，通过在封装结构的第一表面上设置发热层，发热层可以对整个封装结构加热，与传统的方案需要通过导热介质(例如空气或者导热液体等)对封装结构进行加热相比，导热效率更高，因此可以降低功耗。
本申请实施例提供的一种封装结构500如图8所示，包括：内部电路510、封装内部电路510的封装外壳540以及发热层530，封装外壳540具有第一表面520，第一表面520上设置有多个焊脚，其中一部分焊脚与内部电路510连接，内部电路510通过这部分焊脚接收外部电路的信号，或者向外部电路输出信号。其中的另一部分焊脚为无电气特性的焊脚，例如在封装结构500焊接在印制电路板上时为了增加焊接稳定性而设置的空焊脚、接地焊脚等等。
其中第一表面520上设置有第一焊脚521、第二焊脚522，发热层505设置在第一表面520上，发热层505包括连接于第一表面520上的第一焊脚521与第二焊脚522之间的线路。
这里的线路可以由电阻浆料形成，例如在第一表面520上的预设区域涂覆电阻浆料形成的发热层530的线路，当第一焊脚521与第二焊脚522上电同发热层530的线路形成回路时，发热层530的线路可以对整个封装结构500加热，使内部电路510能够维持在相对稳定的工作温度，避免因为温度变化导致内部电路510的工作特性发生变化。
其中，第一焊脚521、第二焊脚522复用封装结构500上不具有电气特性的焊脚，例如可以为空焊脚或者接地焊脚，在封装结构500上设置一些空焊脚可以增强封装结构焊接在印制电路板上的稳定性，而本申请实施例将这些不具有电气特性的焊脚利用起来，利用这些不具有电气特性的焊脚对发热层530的线路上电，对封装结构500整体加热。
上述示例中提及在第一表面520上的预设区域涂覆电阻浆料形成的发热层530的线路，为了确保发热层530发热时能够对封装结构500整体均匀加热，发热层530的线路在第一表面520上均匀分布，换言之，在第一表面520上的预设区域均匀涂覆电阻浆料形成均匀分布的线路。
示例性的，可以在第一表面520上的蛇形区域涂覆电阻浆料，形成蛇形分布的线路。当第一焊脚521与第二焊脚522上电时，发热层530的线路可以发热，并且，发热层530设置在封装结构500的第一表面530上，当发热层530的线路发热时，可以不经过导热介质直接对封装外壳540内的晶振510以及封装外壳540上的各个焊脚(例如第一焊脚521、第二焊脚522)加热，导热效率更高，因此可以降低功耗，从而可以实现低成本、低功耗的恒温晶振方案。
当然，发热层530的线路还可以是其他的形状。例如可以是螺旋形、环形等等。在这里，第一表面520上的各个焊脚的焊接面到第一表面520的距离大于发热层的厚度，例如上述的第一焊脚521的焊接面、第二焊脚522的焊接面与第一表面540的距离大于发热层530的厚度，这样当本申请实施例提供的封装结构500焊接在印制电路板上时，电阻浆料不会与印制电路板接触，可以避免短路，也可以避免对印制电路板上的其他元器件产生影响，电阻浆料与传统的电阻丝和电热管相比，更为高效，环保，节能，成本更低，制备工艺更简单。
电阻浆料包括镍铬合金，镍铬合金成本较低的同时具有良好的发热效率。电阻浆料形成的发热线路与第一焊脚521和第二焊脚522连接，所以在给第一焊脚521和第二焊脚522上电与发热层530的线路形成回路后，电阻浆料会发热，这样发热层530可以迅速实现对封装外壳540和内部的晶振510加热。在热传递过程中减少了不必要的热辐射损失，更加高效，并且由于没有额外引入有源器件，所以并不会造成额外的相位噪声。
以发热层530的线路在第一表面520上蛇形分布为例，在一种可能的实现方式中，第一表面520为矩形，第一焊脚521与第二焊脚522分布在第一表面520的一条对角线的两端，第一焊脚521与第二焊脚522分布在第一表面520的另一条对角线的两端，这样的焊脚分布方式可以提高封装结构500焊接在印制电路板上时的稳定性，在这种情况下蛇形的线路可以有更多的迂回或者弯折形状，与第一表面520的接触面积更大，分布更均匀，这样对封装结构500的加热效率会更高，可以实现更快速度的加热。
同样以发热层530的线路在第一表面520上蛇形分布为例，在另一种可能的实现方式中，第一表面520为矩形，第一焊脚521与所述第二焊脚522还可以分布在第一表面520的一侧(而不是对角线的两端)，第一焊脚521与第二焊脚522分布在第一表面520的另一侧，如图9所示。发热层530的线路的第一端电连接第一焊脚521，第二端电连接第二焊脚522。
上述示例中，封装外壳540的第一表面为矩形，但不限于此，还可以是其他的形状，例如还可以是圆形、椭圆形等等，在这种情况下，发热层530的线路在第一焊脚521和第二焊脚522所在的表面上均匀分布，例如蛇形分布，采用蛇形分布可以增强加热效率，使热量传递更加均匀，或者发热层530的线路还可以是其他的分布方式，例如螺旋形、圆形或者环形等等。
上述封装外壳540可以采用陶瓷材料或者树脂等材料，采用陶瓷材料导热系数高，以提升对封装结构500和内部电路510的加热效率，封装外壳540还可以采用其他导热效果好的封装材料。
当上述的封装结构500焊接在印制电路板上时，第一焊脚521与第二焊脚522可以通过印制电路板上的导线与控制器的电压输出端口连接，从而控制器可以通过调节电压输出端口输出的电压来控制发热层530的发热。
此外，还可以在封装结构500内部或者外部设置温度传感器，该温度传感器用于检测封装结构500的温度，温度传感器可以与控制器连接，以将温度发送至控制器，控制器根据该温度调节电压输出端口输出的电压大小，例如当温度低于预设温度时，增大输出电压，当温度高于预设温度时，降低输出电压，以使晶振工作在相对恒定的 温度环境下，这里的预设温度可以根据晶振的温度特性设定，例如可以设定为145℃。
在一种可能的实现方式中，上述的内部电路510可以包括晶振，晶振包括第一极与第二极，第一表面520上还设置有第三焊脚523与第四焊脚524，晶振的第一极与第三焊脚523连接，第二极与第四焊脚524连接，通过第三焊脚523和第四焊脚524可以连接电源信号或者输出振荡信号。
由于晶振存在温飘现象，当工作温度发生变化时，晶振输出信号的频率会发生变化，这样可能会导致设备无法正常运行，利用本申请实施例提供的封装结构可以对晶振以及各个焊脚加热，能够使晶振维持在相对稳定的工作温度，避免因温飘影而出现跳频等问题，此外，本申请实施例提供的封装结构500的发热层530(不经过导热介质)设置在第一表面520上对封装结构500整体加热，与传统的方案需要通过导热介质(例如空气或者导热液体等)对封装结构进行加热相比，导热效率更高，因此可以降低功耗。
如图10所示为本申请实施例提供的加热效果示意图，颜色越深代表温度越高。可以看到发热层530的线路上电后进行发热，温度最高。热量通过陶瓷材料制成的封装外壳540传导，这样能够对内部的内部电路510和封装结构500上的各个焊脚加热，例如对第一焊脚521、第二焊脚522、第三焊脚523还有第四焊脚524加热，第一焊脚521、第二焊脚522、第三焊脚523还有第四焊脚524与封装外壳540的温度相近，也正是由于陶瓷材料的高导热性，所以能够高效率的加热其中的晶振和第一表面520上的各个焊脚，功耗更低，在2mm×3mm大小的第一表面520上均匀分布的发热层530的线路，只需要8mW左右的功耗即可满足对封装结构500整体加热的需求。
由于发热层530位于封装外壳540的表面，并且发热层530包括连接于第一焊脚521与第二焊脚522之间的线路，线路可以由电阻浆料形成，可以通过对第一焊脚521与第二焊脚522的电压调整来实现对发热量的调节。一般情况下，对材料进行加热到一定的温度实现起来比较容易，但是想要达到相同程度的降温效果却很困难，所以一般将恒温晶振的恒温点设置得较高，这样便于稳定控制恒温晶振的温度，例如，在本申请实施例中，可以将恒温点设置为145℃。
上述示例中，以内部电路510包括晶振为例对本申请实施例提供的封装结构做了介绍，在本申请实施例的其他实施方式中，上述的内部电路还可以是其他的对温度敏感的电路，例如压控振荡器或其他对温度敏感的电路或者电子器件。
此外，本申请实施例还提供了一种电子设备，电子设备包括印制电路板和上述实施例封装结构，封装结构与印制电路板连接，例如，封装结构可以焊接在印制电路板上。封装结构包括第一表面，第一表面上设置有第一焊脚、第二焊脚、第三焊脚、第四焊脚与，当封装结构焊接在印制电路板上时，第一表面与印制电路板之间的距离大于发热层的厚度。
电子设备还包括控制器，控制器设置在印制电路板上，控制器的电压输出端口通过电路板上的导线与第三焊脚、第四焊脚连接，和发热层530的线路形成回路，通过调节输出至第三焊脚或第四焊脚的电压大小调整发热层的发热。
以上所述，仅为本申请的具体实施方式，但本申请的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本申请揭露的技术范围内，可轻易想到变化或替换， 都应涵盖在本申请的保护范围之内。因此，本申请的保护范围应以所述权利要求的保护范围为准。

Claims (13)

  1. 一种封装结构，其特征在于，包括：内部电路、封装所述内部电路的封装外壳；所述封装外壳具有第一表面，所述第一表面上设置有多个焊脚；
    所述第一表面上还包括发热层，所述发热层包括连接于所述第一表面上的第一焊脚与第二焊脚之间的线路。
  2. 根据权利要求1所述的封装结构，其特征在于，所述线路包括设置在所述第一表面的电阻浆料。
  3. 根据权利要求2所述的封装结构，其特征在于，所述线路在所述第一表面上均匀分布。
  4. 根据权利要求3所述的封装结构，其特征在于，所述线路在所述第一表面上蛇形分布。
  5. 根据权利要求1～4任一项所述的封装结构，其特征在于，所述内部电路包括晶振，所述第一表面上设置有第三焊脚和第四焊脚，所述晶振的第一极与所述第三焊脚连接，所述晶振的第二极与所述第四焊脚连接。
  6. 根据权利要求1～5任一所述的封装结构，其特征在于，所述第一表面上的多个焊脚的焊接面与所述第一表面的距离大于所述发热层的厚度。
  7. 根据权利要求1～6任一项所述的封装结构，其特征在于，所述电阻浆料包括镍铬合金。
  8. 根据权利要求1～7任一项所述的封装结构，其特征在于，所述第一焊脚、所述第二焊脚复用所述封装结构上的无电气特性的焊脚。
  9. 根据权利要求1～8任一项所述的封装结构，其特征在于，所述第一焊脚、所述第二焊脚复用所述封装结构上的空焊脚或接地焊脚。
  10. 根据权利要求1～9任一项所述的封装结构，其特征在于，所述封装外壳的材料包括陶瓷材料或树脂材料。
  11. 根据权利要求1～10任一项所述的封装结构，其特征在于，所述第一表面为矩形，所述第一焊脚与所述第二焊脚分布在所述第一表面的一条对角线的两端；所述第三焊脚与所述第四焊脚分布在所述第一表面的另一条对角线的两端。
  12. 一种电子设备，其特征在于，所述电子设备包括印制电路板以及如权利要求1～11任一项所述的封装结构，所述封装结构与所述印制电路板连接。
  13. 根据权利要求12所述的电子设备，其特征在于，所述第一表面与所述印制电路板之间的距离大于所述发热层的厚度。
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