Crystal oscillator structure with stable frequency and packaging method thereof

Abstract

The invention discloses a crystal oscillator structure with stable frequency and a packaging method thereof. The packaging method comprises the following steps: a resonator packaging step: providing a substrate, uniformly inverting a plurality of resonators at corresponding positions on the substrate, packaging and grinding to expose the bottom surfaces of the resonators, and exposing electrode pads on the bottom surfaces of the resonators; a first wiring step: electroplating a stand column on the encapsulating material, electrically connecting the stand column with an electrode pad of the resonator, continuously encapsulating and grinding to expose the top end of the stand column, electroplating a rewiring layer A at the top end of the exposed stand column, electrically leading out the resonator by the rewiring layer A, and rearranging; a heat-conducting insulating block mounting step: mounting a heat-conducting insulating block on the re-wiring layer A, and continuously packaging and grinding to expose the heat-conducting insulating block; the heat conduction insulation block is arranged between the rewiring layer A and the rewiring layer B, heat on the rewiring layer A and the rewiring layer B is balanced, the sensing of the temperature sensing end of the chip is more sensitive, and the precision of the crystal oscillator is higher.

Description

Technical Field

[0001] The invention belongs to the technical field of crystal oscillator packaging, and in particular relates to a frequency-stable crystal oscillator structure and a packaging method thereof. Background Art

[0002] A crystal oscillator refers to a crystal oscillator. There are many types of crystal oscillators, such as clock crystal oscillators. Crystal oscillators are used in mobile phones or electronic watches with time display functions, that is, there must be a clock crystal oscillator to control the display of time. The principle of a crystal oscillator is to use a crystal that can convert electrical energy and mechanical energy into each other to work in a resonant state to provide stable and accurate single-frequency oscillation.

[0003] The existing crystal oscillator structure is to add IC chips and other components to the resonator to form an oscillation circuit. The temperature has a great influence on the crystal oscillator, that is, the thermal expansion effect of the crystal sheet inside the resonator will directly affect the frequency stability of the crystal oscillator. The frequency change caused by the thermal expansion effect can be called thermal expansion frequency deviation. The temperature sensing end on the IC senses the temperature change at the resonator end. The temperature compensation circuit controls the output frequency of the resonator after appropriately transforming the temperature information to achieve the effect of stabilizing the output frequency. However, due to the structural setting of the crystal oscillator, the resonator is electrically stacked on top of the IC chip and is electrically connected to the working area of ​​the circuit board etc. through the pins at the bottom of the IC. The IC temperature sensing end is close to the bottom and the encapsulation material is thin, resulting in the temperature of the working area outside the crystal oscillator affecting the IC temperature sensing end. The temperature sensing end first senses the temperature of the welding position and then senses the temperature around the resonator, resulting in temperature sensing delay and poor frequency stability of the crystal oscillator. Summary of the invention

[0004] In order to solve the above problems in the prior art, the present invention provides a frequency-stable crystal oscillator structure and a packaging method thereof.

[0005] To achieve the above object, the present invention provides a frequency-stable crystal oscillator structure and a packaging method thereof, comprising the following steps: Resonator encapsulation step: providing a substrate, evenly inverting a plurality of resonators at corresponding positions on the substrate, encapsulating and grinding to expose the bottom surface of the resonator, and the electrode pads on the bottom surface of the resonator are also exposed; The first wiring step: electroplating a column on the encapsulation material, the column is electrically connected to the electrode pad of the resonator, the encapsulation is continued and the top of the column is exposed by grinding, and a redistribution layer A is electroplated on the top of the exposed column. The redistribution layer A electrically leads the resonator out and re-layouts it; Thermally conductive insulating block mounting steps: mounting the thermally conductive insulating block on the redistribution layer A, and continuing to encapsulate and grind to expose the thermally conductive insulating block; Second wiring step: electroplating the redistribution layer B on the top of the exposed thermally conductive insulating block, the thermally conductive insulating block balances the heat between the redistribution layer A and the redistribution layer B, electroplating the end of the redistribution layer B with a connection terminal, and again encapsulating and grinding to expose the top of the connection terminal; Chip mounting step: electrically connecting the chip port to the redistribution layer A and the redistribution layer B respectively, and continuing to encapsulate until the chip is completely encapsulated to form an encapsulation top surface; Electrical lead-out step: vertically drill a hole at a corresponding position on the top surface of the package until a connection end of the redistribution layer B is exposed, and electroplate a lead-out column in the hole to electrically lead the chip out of the package through the redistribution layer B; Product unitization step: remove the substrate and vertically cut at the cutting line position to form the crystal oscillator package product unit.

[0006] Furthermore, in the resonator encapsulation step, the resonator includes a base, a crystal piece is horizontally installed in the base groove, a metal cover is provided on the top surface of the base groove, a circuit is provided in the inner wall of the base, and the crystal piece is electrically connected to the electrode pad on the bottom surface of the resonator through the circuit.

[0007] Furthermore, in the thermally conductive insulating block mounting step, a protrusion is electroplated at one end of the redistribution layer A, and the thermally conductive insulating block mounted on the redistribution layer A is flush with the top of the protrusion. After the thermally conductive insulating block is exposed by grinding, the top of the protrusion is also exposed.

[0008] Furthermore, in the second wiring step, while the connection end is electroplated at the end B of the redistribution layer, the exposed top of the protrusion is electroplated and raised to be flush with the top of the connection end, and the connection end and the protrusion are simultaneously encapsulated and polished to expose the flush top.

[0009] Furthermore, in the chip mounting step, the chip port is electrically connected to the redistribution layer A and the redistribution layer B respectively through the exposed connection end and the top of the protrusion.

[0010] A frequency-stable crystal oscillator structure includes a resonator, an electrode pad is provided at the bottom of the resonator, a package is electrically connected to the bottom of the resonator through the electrode pad, and the package contains: Rewiring layer A, which is electrically connected to the electrode pad of the resonator through the pillars, leads out the electrical properties of the resonator and re-layouts it; The chip, wherein the port of the chip is electrically connected to one end of the redistribution layer A, so as to realize the electrical control of the resonator by the chip; Rewiring layer B, one end of the rewiring layer B is electrically connected to the port of the chip through the connection end, and the other end of the rewiring layer B is electrically re-arranged by the chip through the lead-out column and then led out of the package body; The thermally conductive insulating block is mounted between the redistribution layer A and the redistribution layer B to balance the heat between the redistribution layer A and the redistribution layer B.

[0011] Furthermore, the resonator includes a base, a crystal piece is horizontally installed in the base groove, a metal cover is provided on the top surface of the base groove, a circuit is provided in the inner wall of the base, and the crystal piece is electrically connected to the electrode pad on the bottom surface of the resonator through the circuit.

[0012] Furthermore, one end of the redistribution layer A is electroplated with a protrusion, and is electrically connected to the port of the chip through the protrusion.

[0013] Furthermore, the package is formed by encapsulating layer by layer. After the resonator is inverted on the substrate, it is encapsulated and polished for the first time to expose the bottom surface of the resonator, and the electrode pad on the bottom surface of the resonator is also exposed. A column is electroplated on the resonator electrode pad. The second encapsulation and polishing exposes the top of the column. The redistribution layer A electrically connected to the column is further electroplated, and a thermally conductive insulating block is mounted on the redistribution layer A. At the same time, a protrusion with a top that is flush with the thermally conductive insulating block is electroplated at one end of the redistribution layer A. The third encapsulation and polishing exposes the thermally conductive insulating block and the top of the protrusion.

[0014] Furthermore, the redistribution layer B is plated on the exposed top surface of the thermally conductive insulating block, and while the connection end is plated on the redistribution layer B, the exposed top of the protrusion is further plated to be raised to be flush with the top of the connection end. The fourth encapsulation and grinding exposes the connection end and the top of the protrusion flush with each other.

[0015] Furthermore, after the chip is mounted and electrically connected to the redistribution layer A and the redistribution layer B, the chip is encapsulated for the fifth time to completely encapsulate the chip to form an encapsulation top surface.

[0016] Furthermore, a hole is vertically drilled at a corresponding position on the top surface of the package until a connection end of the redistribution layer B is exposed, and a lead-out column is electroplated in the hole to lead the electrical properties of the chip through the redistribution layer B to the outside of the package.

[0017] The present invention: 1. By placing the thermally conductive insulating block between the redistribution layer A and the redistribution layer B, the heat on the redistribution layer A and the redistribution layer B is balanced, the chip temperature sensing end is more sensitive, the temperature compensation circuit in the chip works more stably, and the accuracy of the crystal oscillator is higher; 2. Multiple product units are formed by layer-by-layer encapsulation. The chip, resonator and internal electrical connection structure are reasonably arranged in the encapsulation material, changing the traditional crystal oscillator structure mounting process and making the size controllable. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1-Figure 2 A cross-sectional view of a resonator encapsulation step of a frequency-stable crystal oscillator packaging method of the present invention; Figure 3-Figure 5 A cross-sectional view of a first wiring step of a frequency-stable crystal oscillator packaging method of the present invention; Figure 6-Figure 7 A cross-sectional view of a thermally conductive insulating block mounting step of a frequency-stable crystal oscillator packaging method of the present invention; Figure 8-Figure 9 A cross-sectional view of a second wiring step of a frequency-stable crystal oscillator packaging method of the present invention; Figure 10-11 A cross-sectional view of a chip mounting step of a frequency-stable crystal oscillator packaging method of the present invention; Figure 12-13 A cross-sectional view of an electrical lead-out step of a frequency-stable crystal oscillator packaging method of the present invention; Fig.14 A cross-sectional view of a product unitization step of a frequency-stable crystal oscillator packaging method of the present invention; Fig.15 This is a product cross-sectional view of a frequency-stable crystal oscillator structure of the present invention.

[0019] In the figure: 1. resonator; 2. pillar; 3. redistribution layer A; 4. thermal conductive insulating block; 5. redistribution layer B; 6. chip; 7. lead-out pillar; 8. package body. DETAILED DESCRIPTION

[0020] The content of the present invention will be explained below in conjunction with specific embodiments, examples of which are shown in the accompanying drawings, wherein the same or similar numbers throughout represent the same or similar components or components with the same or similar functions.

[0021] The directional terms mentioned in the present invention, such as: up, down, left, right, front, back, inside, outside, front, back, side, etc., are only reference directions of the drawings. The embodiments described below with reference to the drawings and the directional terms used are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention. In addition, the various specific process and material examples provided in the present invention are all those skilled in the art who can recognize the application of other processes and / or the use of other materials.

[0022] The chip 6 connection structure inside the crystal oscillator body usually includes the following key parts: 1. Resonator 1: This is the core component of the crystal oscillator body, usually made of quartz crystal. Quartz crystal has piezoelectric properties and can generate mechanical vibrations after voltage is applied; 2. Amplifier circuit: The oscillation signal generated by the crystal oscillator is usually weak, so an amplifier circuit is required to amplify these signals. The amplifier circuit is usually composed of transistors or operational amplifiers; 3. Feedback network: In order to maintain continuous oscillation, the output of the amplifier circuit needs to be returned to the input end through the feedback network. The feedback network is usually composed of resistors, capacitors and inductors; 4. Power pin: The crystal oscillator requires power to work, usually including a positive power supply (Vcc) and a ground (GND) pin; 5. Output pin: The amplified oscillation signal is transmitted to the external circuit or chip 6 through the output pin. Specifically, the input pin of the IC chip 6 inside the crystal oscillator body is connected to one end of the resonator 1, the output pin is connected to the other end of the resonator 1, the ground pin is connected to the ground to provide a reference voltage, the power pin is connected to the positive power supply to supply power to the crystal oscillator circuit, and the amplifier circuit and feedback network are usually integrated inside the chip 6 to amplify and feedback the oscillation signal. The resonator 1 generates a stable oscillation frequency, which is amplified by the amplifier circuit and maintained by the feedback network. The final oscillation signal is transmitted to the external circuit or chip 6 through the output pin.

[0023] The crystal oscillator is greatly affected by temperature. The thermal expansion effect of the crystal slice inside the resonator 1 will directly affect the frequency stability of the crystal oscillator. For a crystal oscillator with a positive temperature coefficient, when the temperature rises, the crystal slice will expand and the physical size will change. Since the frequency of the crystal oscillator is proportional to the size of the crystal slice, the temperature increase will make the frequency of the crystal oscillator higher. Similarly, when the temperature drops, the crystal shrinks and the crystal oscillator frequency is lower. The frequency change caused by the thermal expansion effect can be called thermal expansion frequency deviation. Moreover, the excitation power provided by the circuit is too large, which causes the amplitude of the quartz crystal to increase. Therefore, excessive heat generation causes the temperature of the vibration area of ​​the crystal slice to rise, and the crystal slice itself produces a gradient temperature rise, which directly destroys the frequency stability. At the same time, if the temperature is too high or the high temperature time is too long, the risk of the solder joint inside the crystal oscillator body falling off will increase, resulting in defective products. Therefore, the chip 6 inside the crystal oscillator body has temperature sensing capability. The chip 6 senses the temperature change of the resonator 1, and adjusts the external matching capacitor matrix (changes the connected capacitor value) through the temperature compensation circuit. After the temperature information is appropriately transformed, the output frequency of the resonator 1 is controlled to achieve the effect of stabilizing the output frequency.

[0024] The existing crystal oscillator structure is to electrically stack the resonator 1 on the IC chip 6. The IC chip 6 realizes electrical control of the resonator 1 and is electrically connected to the working area of ​​the circuit board through the pins at the bottom of the IC. It can also be electrically connected to other working areas. The sensing end of the IC senses the temperature changes in the surrounding area of ​​the crystal oscillator welding area and provides a temperature compensation circuit to ensure the frequency stability of the crystal oscillator. However, due to the structural setting of the crystal oscillator, the distance between the IC and the circuit board is relatively close, and the encapsulation material between them is relatively thin. The sensing end first senses the temperature of the welding position and then senses the temperature around the resonator, resulting in a temperature sensing delay and poor frequency stability of the crystal oscillator.

[0025] In order to better understand the purpose, structure and function of the present invention, the following Figure 1 -Attached Fig.14 , a frequency-stable crystal oscillator structure and its packaging method proposed by the present invention are further described in detail. The method comprises the following steps: a resonator 1 encapsulation step: providing a substrate, evenly inverting a plurality of resonators 1 at corresponding positions on the substrate, encapsulating and grinding to expose the bottom surface of the resonator 1, and the electrode pads on the bottom surface of the resonator 1 are also exposed; First wiring step: electroplating the pillar 2 on the encapsulation material, the pillar 2 is electrically connected to the electrode pad of the resonator 1, the encapsulation is continued and the top of the pillar 2 is exposed, and the rewiring layer A3 is electroplated on the top of the exposed pillar 2. The rewiring layer A3 electrically leads out the resonator 1 and re-layouts it; Thermally conductive insulating block 4 mounting step: mounting the thermally conductive insulating block 4 on the redistribution layer A3, and continuing to encapsulate and grind to expose the thermally conductive insulating block 4; Second wiring step: electroplating the redistribution layer B5 on the exposed top of the heat-conducting insulating block 4, the heat-conducting insulating block 4 balances the heat between the redistribution layer A3 and the redistribution layer B5, electroplating the end of the redistribution layer B5 with a connection terminal, and again encapsulating and grinding to expose the top of the connection terminal; Chip 6 mounting step: electrically connecting the ports of chip 6 to the redistribution layer A3 and the redistribution layer B5 respectively, and continuing the encapsulation until the chip 6 is completely encapsulated to form an encapsulation top surface; Electrical lead-out step: vertically drill a hole at the corresponding position on the top surface of the package until a connection end of the redistribution layer B5 is exposed, and electroplate a lead-out column 7 in the hole to electrically lead the chip 6 out of the package through the redistribution layer B8; Product unitization step: removing the substrate and vertically cutting at the cutting line position to form the crystal oscillator package 8 product unit.

[0026] Among them, Figure 1-Figure 2As shown, in the resonator 1 encapsulation step, a substrate is provided, the substrate is made of a material commonly used in the art, and can be a resin plate, etc. The resonator 1 is the simplest oscillator without any compensation. This resonator 1 includes a base, which can be a ceramic base. A crystal piece is horizontally installed in the base groove, and a metal cover is covered on the top surface of the base groove. A circuit is provided in the inner wall of the base. An electrode pad is arranged on the bottom surface of the resonator 1, and the crystal piece is electrically connected to the electrode pad on the bottom surface of the resonator 1 through the circuit. The layout is reasonably designed according to the size of the substrate, and a plurality of resonators 1 are evenly inverted at corresponding positions on its upper surface, that is, the metal cover of the resonator 1 is placed toward the substrate to place the entire resonator 1. The encapsulation material is injected into the first encapsulation process to encapsulate the resonator 1. The bottom surface of the resonator 1 facing upward is exposed by horizontal mechanical grinding on the top surface of the encapsulation. At this time, the electrode pad on the bottom surface of the resonator 1 is also exposed, and a layer of metal is electroplated on the exposed electrode pad to increase the height of the electrode pad. The number, distribution position and electrical function of the electrode pad on the resonator 1 are set according to the actual product situation, and the present invention is not limited thereto.

[0027] Among them, Figure 3-Figure 5 As shown, in the first wiring step, electroplating is continued on the electrode pad with increased height to form a column 2, and the column 2 is electroplated on all the electrode pads of the resonator 1. The second encapsulation is continued on the basis of the first encapsulation until the column 2 is completely encapsulated. The top of the column 2 is exposed by horizontal mechanical grinding on the top surface of the encapsulation, and electroplating is continued on the ground encapsulation surface to form a rewiring layer A3. One end of the rewiring layer A3 is electrically connected to the column 2. The rewiring layer A3 leads out the electrical properties of the resonator 1 and rearranges it. The electrical direction of the rearrangement is designed according to the actual product situation. Since the rewiring layer A3 is flatly plated on the encapsulation surface, it is necessary to plate a protrusion at the electrically connected end. The protrusion serves as a conductive structure for electrically connecting the rewiring layer A3 to other components.

[0028] Among them, Figure 6-Figure 7 As shown, in the step of mounting the thermally conductive insulating block 4, the thermally conductive insulating block 4 is mounted on the corresponding position of the redistribution layer A3, and the thermally conductive insulating block 4 is bonded to the corresponding area by a colloid, and the colloid is an insulating heat-conducting colloid. The top surface of the thermally conductive insulating block 4 after mounting is flush with the top surface of the protrusion at the electrical connection end of the redistribution layer A3, that is, the thermally conductive insulating block 4 and the protrusion are arranged at different positions on the redistribution layer A3, and the third encapsulation is continued on the encapsulation surface after the second encapsulation grinding, and the thermally conductive insulating block 4 and the protrusion are completely encapsulated, and horizontal mechanical grinding is continued on the top surface of the encapsulation to expose the top surface of the thermally conductive insulating block 4 and the protrusion.

[0029] The thermally conductive insulating block 4 is a block product of thermally conductive insulating material made of silica gel and glass fiber (or imide film) as the base material, and is produced through special processes such as coating and casting. Due to its excellent thermal conductivity, insulation, high dielectric constant, low thermal resistance and easy assembly, it is widely used in the electronic and electrical industries. The thermally conductive insulating block 4 can be formed of a variety of material components, and the present invention does not limit this.

[0030] Among them, Figure 8-Figure 9 As shown, in the second wiring step, the rewiring layer B5 is further electroplated on the ground package surface, and the rewiring layer B5 is bonded to the top surface of the thermally conductive insulating block 4, that is, the thermally conductive insulating block 4 is arranged between the rewiring layer A3 and the rewiring layer B5 to balance the heat on the rewiring layer A3 and the rewiring layer B5. Since the rewiring layer A3 and the rewiring layer B5 are electroplated metal materials and the thermal resistance of the packaging material is relatively large, the heat transferred outside the crystal oscillator package body on the rewiring layer A3 and the rewiring layer B5 is relatively large. The rewiring layer A3 is closer to the resonator 1, and the rewiring layer B5 is closer to the bottom surface of the crystal oscillator package body, and there is a difference in the transferred heat. The heat of the rewiring layer A3 and the rewiring layer B5 is balanced by the thermally conductive insulating block 4, and there is no difference in the transferred heat. The temperature sensing end of the chip 6 is more sensitive, and the temperature compensation circuit in the chip 6 works more stably, so that the accuracy of the crystal oscillator body is higher.

[0031] The temperature compensation circuit plays a role in temperature compensation of the crystal oscillator frequency. By sensing the ambient temperature, the temperature information is appropriately transformed to control the output frequency of the crystal oscillator to achieve the effect of stabilizing the output frequency.

[0032] Similarly, the redistribution layer B5 is plated flat on the encapsulation surface, so a connection terminal of a certain height must be plated on it. The connection terminal is plated at the end of the redistribution layer B5, and at the same time, the exposed top surface of the protrusion is plated to be flush with the top of the connection terminal. The fourth encapsulation continues on the basis of the third encapsulation, completely encapsulating the connection terminal and the protrusion, and horizontal mechanical grinding is performed on the top surface of the encapsulation to expose the connection terminal and the top of the protrusion.

[0033] Among them, Figure 10-11 As shown, in the chip 6 mounting step, the chip 6 port is aligned with a connection end and a protrusion of the redistribution layer B5, and the chip 6 port is welded to the connection end and the protrusion through a welding process, thereby realizing chip 6 mounting. In order to ensure that the chip 6 port is accurately aligned, the port position on the chip 6 and the position and size of the redistribution layer A3, the protrusion, the redistribution layer B5 and the connection end are all taken into consideration in the product design stage.

[0034] After chip 6 is mounted, chip 6 is electrically connected to resonator 1 through protrusions, redistribution layer A3, pillars 2 and electrode pads, thereby realizing electrical control of resonator 1 by chip 6; redistribution layer B5 re-layouts the electrical direction of chip 6 through the connection end, and the fifth encapsulation is continued on the basis of the fourth encapsulation to completely encapsulate chip 6, with the top surface of the encapsulation being horizontal and flat.

[0035] Among them, Figure 12-13 As shown, in the electrical lead-out step, a hole is drilled vertically downward at the corresponding position on the top surface of the package until the top of the other connection end of the redistribution layer B5 is exposed, and a lead-out column 7 is electroplated in the drilled hole through an electroplating process. The bottom end of the lead-out column 7 is electrically connected to the connection end, and the top end of the lead-out column 7 is flush with the top surface of the package and exposed. The electrical properties of the chip 6 are transferred from one connection end to the redistribution layer B5 for rewiring, and then transferred from the other connection end to the lead-out column 7, and then transferred to the outside of the crystal oscillator package 8. The exposed top surface of the lead-out column 7 serves as an interface for electrical connection between the outside world and the crystal oscillator package 8, and the entire encapsulation process is completed through a layer-by-layer encapsulation process.

[0036] Among them, Fig.14 As shown, in the product unitization step, the substrate is removed by mechanical stripping. Since multiple resonators 1 are evenly placed on the substrate, multiple product units are formed by layer-by-layer encapsulation. The chip, resonator and internal electrical connection structure are reasonably arranged in the encapsulation material, which changes the traditional crystal oscillator structure mounting process. The size is controllable, and the package as a whole is reserved with cutting paths in the corresponding area during the product design stage. After the encapsulation is completed, the encapsulation material is cut by a cutting knife at the cutting path position to separate it into product units. The cutting can be performed along the encapsulation material on the side of the resonator 1, that is, the resonator 1 is not encapsulated by the encapsulation material, so that the final product unit constitutes a stack of the resonator 1 and the encapsulation body 8 below it; the cutting may not be performed along the encapsulation material on the side of the resonator 1, but part of the encapsulation material is retained on the side of the resonator 1, so that the resonator 1 and the chip 6 constitute an integral encapsulation body 8.

[0037] A frequency-stable crystal oscillator structure can be obtained by the above-mentioned frequency-stable crystal oscillator packaging method, such as Fig.15 As shown, the structure includes a resonator 1, an electrode pad is arranged at the bottom of the resonator 1, the resonator 1 includes a base, a crystal piece is horizontally installed in the base groove, a metal cover is arranged on the top surface of the base groove, a circuit is arranged in the inner wall of the base, the crystal piece is electrically connected to the electrode pad on the bottom surface of the resonator 1 through the circuit, and a package 8 is electrically connected to the bottom of the resonator 1 through the electrode pad, and the package 8 encapsulates: Rewiring layer A3, the rewiring layer A3 is electrically connected to the electrode pad of the resonator 1 through the pillar 2, the electrical properties of the resonator 1 are led out and re-arranged, one end of the rewiring layer A3 is electroplated with a protrusion, and the protrusion is electrically connected to the port of the chip 6; Chip 6, the port of the mounted chip 6 is electrically connected to one end of the redistribution layer A3, so that the chip 6 can electrically control the resonator 1; A redistribution layer B5, one end of which is electrically connected to a port of a chip 6 via a connection end, and the other end of which is electrically re-arranged to lead the chip 6 out of a package body 8 via a lead-out column 7; The heat-conducting insulating block 4 is mounted between the redistribution layer A3 and the redistribution layer B5 to balance the heat between the redistribution layer A3 and the redistribution layer B5.

[0038] The package body 8 is formed by encapsulating layer by layer. After the resonator 1 is inverted on the substrate, the bottom surface of the resonator 1 is exposed by the first encapsulation and grinding. The electrode pad on the bottom surface of the resonator 1 is also exposed. The column 2 is electroplated on the electrode pad of the resonator 1. The top of the column 2 is exposed by the second encapsulation and grinding. The redistribution layer A3 electrically connected to the column 2 is continuously electroplated, and the heat-conducting insulating block 4 is mounted on the redistribution layer A3. At the same time, a protrusion whose top is flush with the heat-conducting insulating block 4 is electroplated at one end of the redistribution layer A3. The heat-conducting insulating block 4 and the top of the protrusion are exposed by the third encapsulation and grinding. The redistribution layer A5 is electrically connected to the column 2. The heat-conducting insulating block 4 ... Electroplating is performed on the exposed top surface of the thermally conductive insulating block 4, while the connecting end is electroplated on the redistribution layer B5. At the same time, electroplating continues on the exposed top of the protrusion to raise it flush with the top of the connecting end. The fourth encapsulation and grinding exposes the connecting end and the top flush with the protrusion. After the chip 6 is mounted and electrically connected to the redistribution layer A3 and the redistribution layer B5, the fifth encapsulation is performed to completely encapsulate the chip 6 to form an encapsulation top surface. A hole is vertically drilled at the corresponding position of the encapsulation top surface until a connecting end of the redistribution layer B5 is exposed. A lead-out column 7 is electroplated in the hole to lead the electrical properties of the chip 6 to the outside of the encapsulation material through the redistribution layer B5.

[0039] The packaging material used in the present invention can be epoxy resin, cyanate, polyimide, etc., which has low cost and good curing performance. The packaging process plays an important role in the field of semiconductor manufacturing, mainly in protection, connection, support, reliability and promotion of technological progress. The protection function refers to the chip 6 packaging can protect the chip 6 from mechanical damage, moisture, dust and other external environmental factors, ensuring the normal operation of the chip 6 in extreme environments; the connection function refers to the packaging provides a way to connect the chip 6 with other electronic components, so that the chip 6 can be installed and used on the circuit board; the support function refers to the packaging while supporting the chip 6, it can fix the chip 6 to prevent it from being damaged; reliability refers to the increasingly high reliability requirements for packaging materials and processes to ensure that the chip 6 can operate normally in various extreme environments.

[0040] All the steps of the electroplating process of the present invention are to first form electroplating protection on the surface through exposure and development photolithography technology, and then form a metal seed layer in the area to be electroplated by sputtering or copper deposition or other appropriate methods. The metal seed layer is made of copper or other metal materials. The metal seed layer is to ensure the bonding force between the subsequent electroplated metal and the encapsulation material, and at the same time provide a surface for the electroplating to attach conductive ions to ensure the electroplating effect. The entire steps in the electroplating process and the materials used are also technical common sense in this field.

[0041] The present invention balances the heat on the rewiring layer A3 and the rewiring layer B5 by arranging the thermally conductive insulating block 4 between the rewiring layer A3 and the rewiring layer B5. Since the rewiring layer A3 and the rewiring layer B5 are electroplated metal materials and the thermal resistance of the packaging material is relatively large, the heat transferred from the rewiring layer A3 and the rewiring layer B5 to the outside of the crystal oscillator package 8 is relatively large. The rewiring layer A3 is closer to the resonator 1, while the rewiring layer B5 is closer to the bottom surface of the crystal oscillator package 8, and there is a difference in the amount of heat transferred. The heat of the rewiring layer A3 and the rewiring layer B5 is balanced by the thermally conductive insulating block 4, and there is no difference in the amount of heat transferred. The temperature sensing end of the chip 6 is more sensitive, and the temperature compensation circuit in the chip 6 works more stably, so that the accuracy of the crystal oscillator is higher. Multiple product units are formed by layer-by-layer encapsulation, and the chip 6, the resonator 1 and the internal electrical connection structure are reasonably arranged in the encapsulation material, which changes the traditional crystal oscillator structure mounting process and has controllable size.

[0042] It is to be understood that the present invention is described by some embodiments, and it is known to those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of the present invention are within the scope of protection of the present invention.

Claims

1. A method for packaging a frequency-stable crystal oscillator, characterized in that: The following steps are involved: Resonator encapsulation step: providing a substrate, evenly inverting a plurality of resonators at corresponding positions on the substrate, encapsulating and grinding to expose the bottom surface of the resonator, and the electrode pads on the bottom surface of the resonator are also exposed; The first wiring step: electroplating a column on the encapsulation material, the column is electrically connected to the electrode pad of the resonator, the encapsulation is continued and the top of the column is exposed by grinding, and a redistribution layer A is electroplated on the top of the exposed column. The redistribution layer A electrically leads the resonator out and re-layouts it; Thermally conductive insulating block mounting steps: mounting the thermally conductive insulating block on the redistribution layer A, and continuing to encapsulate and grind to expose the thermally conductive insulating block; Second wiring step: electroplating the redistribution layer B on the top of the exposed thermally conductive insulating block, the thermally conductive insulating block balances the heat between the redistribution layer A and the redistribution layer B, electroplating the end of the redistribution layer B with a connection terminal, and again encapsulating and grinding to expose the top of the connection terminal; Chip mounting step: electrically connecting the chip port to the redistribution layer A and the redistribution layer B respectively, and continuing to encapsulate until the chip is completely encapsulated to form an encapsulation top surface; Electrical lead-out step: vertically drill a hole at a corresponding position on the top surface of the package until a connection end of the redistribution layer B is exposed, and electroplate a lead-out column in the hole to electrically lead the chip out of the package through the redistribution layer B; Product unitization step: remove the substrate and vertically cut at the cutting line position to form the crystal oscillator package product unit.

2. The frequency-stable crystal oscillator packaging method according to claim 1, characterized in that: In the resonator encapsulation step, the resonator includes a base, a crystal piece is horizontally installed in the base groove, a metal cover is provided on the top surface of the base groove, a circuit is provided in the inner wall of the base, and the crystal piece is electrically connected to the electrode pad on the bottom surface of the resonator through the circuit.

3. The frequency-stable crystal oscillator packaging method according to claim 1, characterized in that: In the thermally conductive insulating block mounting step, a protrusion is electroplated on one end of the redistribution layer A, and the thermally conductive insulating block mounted on the redistribution layer A is flush with the top of the protrusion. After the thermally conductive insulating block is exposed by grinding, the top of the protrusion is also exposed.

4. The frequency-stable crystal oscillator packaging method according to claim 3, characterized in that: In the second wiring step, while the connection end is electroplated at the B end of the redistribution layer, the exposed top of the protrusion is electroplated and raised to be flush with the top of the connection end. The connection end and the protrusion are simultaneously encapsulated and polished to expose the flush top.

5. The frequency-stable crystal oscillator packaging method according to claim 4, characterized in that: In the chip mounting step, the chip port is electrically connected to the redistribution layer A and the redistribution layer B respectively through the exposed connection end and the top of the protrusion.

6. A frequency-stable crystal oscillator structure, comprising a resonator, an electrode pad being arranged at the bottom of the resonator, characterized in that: The lower side of the resonator is electrically connected to a package body through an electrode pad, and the package body contains: Rewiring layer A, which is electrically connected to the electrode pad of the resonator through the pillars, leads out the electrical properties of the resonator and re-layouts it; The chip, wherein the port of the chip is electrically connected to one end of the redistribution layer A, so as to realize the electrical control of the resonator by the chip; Rewiring layer B, one end of the rewiring layer B is electrically connected to the port of the chip through the connection end, and the other end of the rewiring layer B is electrically re-arranged by the chip through the lead-out column and then led out of the package body; The thermally conductive insulating block is mounted between the redistribution layer A and the redistribution layer B to balance the heat between the redistribution layer A and the redistribution layer B.

7. The frequency-stable crystal oscillator structure according to claim 6, characterized in that: The resonator comprises a base, a crystal piece is horizontally installed in a groove of the base, a metal cover is arranged on the top surface of the groove of the base, a circuit is arranged in the inner wall of the base, and the crystal piece is electrically connected to the electrode pad on the bottom surface of the resonator through the circuit.

8. The frequency-stable crystal oscillator structure according to claim 6, characterized in that: One end of the redistribution layer A is electroplated with a protrusion, which is electrically connected to the port of the chip through the protrusion.

9. The frequency-stable crystal oscillator structure according to claim 8, characterized in that: The package is formed by encapsulation layer by layer. After the resonator is inverted on the substrate, it is encapsulated and polished for the first time to expose the bottom surface of the resonator, and the electrode pad on the bottom surface of the resonator is also exposed. A column is electroplated on the resonator electrode pad. The second encapsulation and polishing exposes the top of the column. The redistribution layer A electrically connected to the column is further electroplated, and a thermally conductive insulating block is mounted on the redistribution layer A. At the same time, a protrusion with a top flush with the thermally conductive insulating block is electroplated at one end of the redistribution layer A. The third encapsulation and polishing exposes the thermally conductive insulating block and the top of the protrusion.

10. The frequency-stable crystal oscillator structure according to claim 9, characterized in that: The redistribution layer B is plated on the exposed top surface of the thermally conductive insulating block. While the connection end is plated on the redistribution layer B, the exposed top of the protrusion is continuously plated to be flush with the top of the connection end. The fourth encapsulation and grinding exposes the connection end and the top of the protrusion flush with each other.

11. The frequency-stable crystal oscillator structure according to claim 10, characterized in that: After the chip is mounted and electrically connected to the redistribution layer A and the redistribution layer B, the chip is completely encapsulated for the fifth time to form an encapsulation top surface.

12. The frequency-stable crystal oscillator structure according to claim 11, characterized in that: A hole is vertically drilled at a corresponding position on the top surface of the package until a connection end of the redistribution layer B is exposed, and a lead-out column is electroplated in the hole to lead the electrical properties of the chip out of the package through the redistribution layer B.

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