EMC (Electro Magnetic Compatibility) shielding structure of voltage doubling rectifying circuit board and electric flame stove

Abstract

The invention discloses an EMC (Electro Magnetic Compatibility) shielding structure of a voltage-multiplying rectifying circuit board and an electric flame stove. The EMC shielding structure comprises a PCB (Printed Circuit Board) and a plurality of groups of voltage-multiplying rectifying units arranged on two surfaces of the PCB, through the combined design of the independent shielding fence and the fully-wrapped aluminum film shielding layer, each group of voltage-multiplying rectifying units is enclosed into an independent electromagnetic shielding space, a sheet metal structure of the fence forms a physical isolation barrier, and the aluminum film shielding layer guides electromagnetic radiation into a ground wire through a copper foil, so that the electromagnetic shielding effect is improved. Mutual interference of electromagnetic radiation generated when the voltage doubling rectifying units work is blocked, and fluctuation of output voltage is avoided. Meanwhile, the leakage amount of external electromagnetic radiation is effectively controlled, interference on other electronic components such as a control chip and a sensor in the electric flame stove is avoided, and electromagnetic compatibility is achieved. According to the processing technology, mature automatic technologies such as SMT, vacuum defoaming and vacuum aluminum plating are adopted, an existing electronic element production line can be adapted, the technology cost is greatly reduced, and meanwhile the mass production efficiency is improved.

Description

EMC shielding structure of voltage doubler rectifier circuit board and electric flame stove Technical Field

[0001] This invention specifically relates to an electric flame stove. Background Technology

[0002] Electric flame stoves employ multiple high-voltage discharge devices (connected in parallel with positive and negative electrodes in a closed-circuit discharge configuration). Each device generates an electric field by blasting gas flow through high voltage. The gas flow collides with electrons in this electric field, ionizing the gas molecules and exciting plasma. This plasma, with a temperature exceeding 1000 degrees Celsius, is used to heat cookware. Currently, electric flame stoves on the market are also known as electric fire stoves, electric fire starter stoves, electric flame stoves, electric gas stoves, electric open flame stoves, plasma stoves, etc. All of these stoves utilize the working principle of high-voltage breakdown to excite plasma for heating cookware.

[0003] For example, the invention patent with publication number CN121077225A discloses a high-voltage circuit for an electric flame stove, including: a PFC circuit, a high-frequency conversion circuit, a step-up transformer, an energy coupling circuit, and a voltage multiplier circuit connected in sequence. The voltage multiplier circuit is composed of multiple capacitors and multiple diodes, and outputs a stable DC high-voltage current, enabling the high-voltage discharge device to stably break down the air.

[0004] However, in the aforementioned patented technical solution, the high-frequency current output of the transformer causes the diodes in the voltage multiplier circuit to periodically turn on / off. The high-frequency reverse recovery of the diodes leads to the generation of high-frequency current spikes, which in turn cause periodic high-frequency interference to the entire circuit, thereby affecting the system's EMC performance.

[0005] This invention improves an electromagnetically compatible electric flame stove that can be mass-produced using mature processes, in order to meet the electromagnetic radiation restrictions for civilian electronic devices. Summary of the Invention

[0006] To overcome the shortcomings mentioned above, the present invention aims to provide a technical solution that can solve the above problems.

[0007] An EMC shielding structure for a voltage doubler rectifier circuit board, used in an electric flame stove, includes: a PCB board and multiple sets of voltage doubler rectifier units disposed on both sides of the PCB board; each set of voltage doubler rectifier units has an independent shielding fence on its outer side, the shielding fence surrounding the outer perimeter of its corresponding voltage doubler rectifier unit, and one side of the shielding fence is pasted and fixed to the surface of the circuit board; the surface of the voltage doubler rectifier unit is covered with thermally conductive insulating adhesive, the surface of the thermally conductive insulating adhesive is plated with an aluminum film shielding layer, the aluminum film shielding layer is connected to the ground wire through copper foil on the PCB board; the surface of the aluminum film shielding layer is wrapped with a polyimide film, the end of the polyimide film is fixed with a single-sided pressure-sensitive adhesive film, and the single-sided pressure-sensitive adhesive film completely covers the overlap of the polyimide protective film. The seam; the voltage doubler rectifier unit consists of multiple capacitors and multiple diodes, the capacitors and diodes are surface mount type, and the voltage doubler rectifier unit forms an N times voltage output, where N is an integer equal to or greater than 2; the processing technology of the EMC shielding structure of the voltage doubler rectifier circuit board includes: S1, soldering multiple capacitors and multiple diodes constituting the voltage doubler rectifier unit to preset pads on the PCB board using SMT surface mount technology to form multiple sets of voltage doubler rectifier units; S2, attaching multiple sets of independent shielding fences to preset positions on the PCB board surface, corresponding to each set of voltage doubler rectifier units, and fixing them with high-temperature resistant adhesive; S3, uniformly coating the outer surface of each set of voltage doubler rectifier units with thermally conductive insulating adhesive, and curing it after vacuum degassing; S4. An aluminum film shielding layer is coated onto the surface of the cured thermally conductive insulating adhesive layer. At the positions corresponding to the copper foil on the PCB board, flying wires are soldered to achieve electrical connection between the aluminum film and the copper foil. S5. A polyimide film is tightly wrapped around the outside of the aluminum film shielding layer. A single-sided pressure-sensitive adhesive film is applied to the overlapping ends of the polyimide film and compacted to completely cover the overlap seam. S6. The treated circuit board undergoes a 10,000-volt withstand voltage test and an EMC shielding effectiveness test to ensure it meets the requirements for use in electric flame stoves. In step S6, the 10,000-volt withstand voltage test involves applying a test voltage to all voltage doubler rectifier units for more than 3600 seconds. The test voltage is 1.5 times the normal operating voltage of the voltage doubler rectifier units. In step S6, the EMC shielding... The specific method for shielding effectiveness testing is as follows: (1) Assembly preparation: Install the test voltage doubler rectifier circuit board under the burner head of the electric flame stove. Each voltage doubler rectifier unit is individually electrically connected to the corresponding discharge device on the burner head. Place the assembled test circuit board together with the burner head into the microwave anechoic chamber; (2) Working condition simulation: Apply working voltage to the test voltage doubler rectifier circuit board to make the discharge device work normally and simulate the actual operating conditions of the electric flame stove; (3) Signal acquisition: Obtain abnormal signal data output by all voltage doubler rectifier units under different interference intensities through the signal receiving equipment in the microwave anechoic chamber; (4) Effectiveness judgment: Compare the collected abnormal signal threshold with the standard threshold and calculate the difference score. When the difference score is less than the preset qualified threshold, the EMC shielding effectiveness is judged to meet the standard.

[0008] The present invention also proposes an electric flame stove, wherein the electric flame stove includes the EMC shielding structure of the voltage doubler rectifier circuit board described in any of the above claims.

[0009] Compared with existing technologies, the advantages of this invention are as follows: This invention utilizes a combination of independent shielding fences and a fully enclosed aluminum film shielding layer. Each voltage doubler rectifier unit is enclosed in an independent electromagnetic shielding space. The sheet-like metal structure of the fence forms a physical isolation barrier, and the aluminum film shielding layer guides electromagnetic radiation to the ground wire through copper foil. The synergistic effect of both significantly improves the shielding effectiveness between groups, completely blocking mutual interference of electromagnetic radiation generated by each group of voltage doubler rectifier units during operation, and avoiding output voltage fluctuations caused by coupling. Simultaneously, the leakage of external electromagnetic radiation is effectively controlled, preventing interference to internal control chips, sensors, and other electronic components of the electric flame stove, achieving electromagnetic compatibility, and meeting the electromagnetic radiation requirements of civilian electronic devices. To meet emission limit requirements and improve product compliance, this invention utilizes a polyimide film, a high-insulation polymer material, to effectively isolate the aluminum film shielding layer from other metal components or adjacent circuits inside the electric flame stove. The polyimide film tightly wraps the aluminum film shielding layer, completely eliminating the discharge hazard of the entire shielding structure. The processing technology of this invention employs mature automated processes such as SMT surface mount technology, vacuum degassing, and vacuum aluminizing, requiring no specialized customized equipment and adaptable to existing electronic component production lines, significantly reducing process costs and improving mass production efficiency. The EMC shielding structure of the voltage doubler rectifier circuit board of this invention uses an aluminum film shielding layer as a shielding cover, achieving a lightweight design and further reducing the weight of the electric flame stove.

[0010] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 is a schematic diagram of the voltage doubler rectifier circuit board after the completion of the processing step S2 of the present invention.

[0013] Figure 2 is a cross-sectional schematic diagram of the voltage doubler rectifier circuit board after all processing steps of the present invention have been completed. Detailed Implementation

[0014] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0015] In the description of this invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0016] Furthermore, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal connection of two components; they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0017] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0018] Please refer to Figures 1 and 2. In this embodiment of the invention, an EMC shielding structure of a voltage doubler rectifier circuit board is used for an electric flame stove, including: a PCB board 1 and multiple sets of voltage doubler rectifier units 2 disposed on both sides of the PCB board 1.

[0019] In this embodiment of the invention, the PCB board 1 is made of epoxy board, and six to 20 sets of voltage multiplier rectifier units 2 are provided on each side. Each set of units consists of multiple surface-mount capacitors 21 and multiple surface-mount diodes 22 to form a voltage output of two to five times, with a rated output voltage of 7000-10000 volts. The edge of the PCB board 1 is provided with copper foil 6, which is electrically connected to the ground wire.

[0020] In this embodiment of the invention, each voltage doubler rectifier unit 2 is provided with an independent shielding fence 7 on its outer side; the shielding fence 7 is made of metal and is formed into a rectangular frame by stamping. The shielding fence 7 surrounds the outer periphery of its corresponding voltage doubler rectifier unit 2, and one side of the shielding fence 7 is pasted and fixed to the surface of the circuit board.

[0021] In this embodiment of the invention, the surface of the voltage doubler rectifier unit 2 is coated with thermally conductive insulating adhesive 3. This thermally conductive insulating adhesive 3 is available from the prior art, and its specific composition will not be described in detail here. The thermally conductive insulating adhesive 3 completely fills the gap between the components (capacitor 21 and diode 22). After the thermally conductive insulating adhesive 3 has cured, an aluminum film shielding layer 4 is deposited on the surface of the cured thermally conductive insulating adhesive 3 using a vacuum aluminum plating process. It is then welded to the copper foil 6 via a flying wire and connected to the ground wire.

[0022] This invention combines an independent shielding fence 7 with a fully enclosed aluminum film shielding layer 4. Each voltage doubler rectifier unit 2 is enclosed as an independent electromagnetic shielding space. The sheet-like metal structure of the fence forms a physical isolation barrier, and the aluminum film shielding layer 4 guides electromagnetic radiation to the ground wire through copper foil 6. The synergistic effect of the two greatly improves the shielding effectiveness between groups, completely blocking the mutual interference of electromagnetic radiation generated by each group of voltage doubler rectifier units 2 during operation, and avoiding output voltage fluctuations caused by coupling.

[0023] At the same time, the leakage of external electromagnetic radiation is effectively controlled, avoiding interference with other electronic components such as the internal control chip and sensors of the electric flame stove, achieving electromagnetic compatibility, meeting the electromagnetic radiation limit requirements for civilian electronic equipment, and improving product compliance.

[0024] In this embodiment of the invention, a polyimide film 5 is wrapped around the surface of the aluminum film shielding layer 4. The ends of the polyimide film 5 are fixed with a single-sided pressure-sensitive adhesive film (not shown in the attached figure), and the single-sided pressure-sensitive adhesive film completely covers the overlap seam of the polyimide protective film. In this embodiment, the high-frequency electromagnetic waves generated by the high-frequency reverse of the diode are sufficient to generate current in the aluminum film shielding layer 4. The sharp corners of the aluminum film shielding layer 4 are also prone to forming current loops with external conductors, which not only damages the insulation but also interferes with the shielding effect. The polyimide film 5 is a polymer material with high insulation performance, which can effectively isolate the aluminum film shielding layer 4 from other metal components or adjacent circuits inside the electric flame stove. After the polyimide film 5 tightly wraps the aluminum film shielding layer 4, the discharge hazard of the entire shielding structure can be completely eliminated.

[0025] In this embodiment of the invention, the EMC shielding structure of the voltage doubler rectifier circuit board of the present invention uses an aluminum film shielding layer 4 as a shielding cover, which realizes a lightweight design and further reduces the weight of the electric flame stove.

[0026] In this embodiment of the invention, the voltage doubler rectifier unit 2 is composed of multiple capacitors 21 and multiple diodes 22. The capacitors 21 and diodes 22 are surface mount type, and the voltage doubler rectifier unit 2 forms a voltage output of 2-5 times.

[0027] In this embodiment of the invention, the processing technology of the EMC shielding structure of the voltage doubler rectifier circuit board includes: S1, using SMT placement equipment to solder the surface mount capacitor 21 and diode 22 to the preset pads on the PCB board 1, and inspecting the solder joints after cooling to ensure that there are no cold solder joints or solder bridges; S2, applying epoxy adhesive to the stamped shielding fence 7 and attaching it to the outer periphery of each group of voltage doubler units on the surface of the PCB board 1, and curing at room temperature to ensure that the fence and the PCB board 1 are bonded without gaps; S3, injecting thermally conductive insulating adhesive 3 into the shielding fence 7 so that the thermally conductive insulating adhesive 3 covers each group of voltage doubler rectifier units 2. Capacitor 21 and diode 22, after vacuum degassing, are cured at room temperature to form a dense insulating adhesive layer; S4, an aluminum film shielding layer 4 is deposited on the surface of the cured thermally conductive insulating adhesive layer 3 using a vacuum coating machine. At the corresponding soldering points of the aluminum film shielding layer 4 and the copper foil 6 of the PCB board 1, one end of a flying wire is soldered to the aluminum film shielding layer 4, and the other end of the flying wire is soldered to the copper foil 6, thus realizing the electrical connection between the aluminum film shielding layer 4 and the copper foil 6; S5, a polyimide film 5 is wrapped around the outside of the aluminum film shielding layer 4, and a single-sided pressure-sensitive adhesive film is applied to the overlapping end of the polyimide film 5. After compaction, the single-sided pressure-sensitive adhesive... The membrane completely covers the overlap seam; S6, the treated circuit board is subjected to a 10,000-volt withstand voltage test and an EMC shielding effectiveness test to ensure that it meets the requirements for use in the electric flame stove; in step S6, the 10,000-volt withstand voltage test is to apply a test voltage to all voltage doubler rectifier units 2 and continue the test for more than 3,600 seconds. The test voltage is 1.5 times the normal operating voltage of the voltage doubler rectifier unit 2; in step S6, the specific method of the EMC shielding effectiveness test is as follows: (1) Assembly preparation: the voltage doubler rectifier circuit board to be tested is installed under the burner head of the electric flame stove, and each group of voltage doubler rectifier units 2 is individually electrically connected to the burner head. (1) Place the assembled circuit board under test along with the stove head into the microwave anechoic chamber; (2) Working condition simulation: Apply working voltage to the circuit board under test to make the discharge device work normally and simulate the actual working condition of the electric flame stove; (3) Signal acquisition: Obtain abnormal signal data of all voltage doubler rectifier units 2 under different interference intensities through the signal receiving equipment in the microwave anechoic chamber; (4) Performance judgment: Compare the collected abnormal signal threshold with the standard threshold and calculate the difference score. When the difference score is less than the preset qualified threshold, it is determined that the EMC shielding performance meets the standard.

[0028] The processing technology of this invention adopts mature automated processes such as SMT placement, vacuum degassing, and vacuum metallization. It does not require special customized equipment and can be adapted to existing electronic component production lines, which significantly reduces process costs and improves mass production efficiency.

[0029] The present invention also proposes an electric flame stove, which includes the EMC shielding structure of the voltage doubler rectifier circuit board of any of the above-mentioned components, and also includes a burner head and a discharge device.

[0030] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. An EMC shielding structure for a voltage doubler rectifier circuit board, used in an electric flame stove, characterized in that, include: The system comprises a PCB board and multiple voltage doubler rectifier units disposed on both sides of the PCB board. Each voltage doubler rectifier unit is equipped with an independent shielding fence, which surrounds the outer perimeter of its corresponding voltage doubler rectifier unit, and one side of the shielding fence is adhered and fixed to the surface of the circuit board. The surface of the voltage doubler rectifier unit is covered with thermally conductive insulating adhesive, and the surface of the thermally conductive insulating adhesive is coated with an aluminum film shielding layer. The aluminum film shielding layer is connected to the ground wire through copper foil on the PCB board. The surface of the aluminum film shielding layer is wrapped with a polyimide film, and the ends of the polyimide film are fixed with a single-sided pressure-sensitive adhesive film, and the single-sided pressure-sensitive adhesive film completely covers the overlap seam of the polyimide protective film.

2. The EMC shielding structure of the voltage doubler rectifier circuit board according to claim 1, characterized in that, The voltage doubler rectifier unit consists of multiple capacitors and multiple diodes. The capacitors and diodes are surface-mount type. The voltage doubler rectifier unit generates an N times voltage output, where N is an integer equal to or greater than 2.

3. A processing method for the EMC shielding structure of the voltage doubler rectifier circuit board according to any one of claims 1-2, characterized in that, include: S1. Multiple capacitors and diodes constituting the voltage doubler rectifier unit are soldered onto pre-set pads on the PCB board using SMT surface mount technology to form multiple voltage doubler rectifier units. S2. Multiple independent shielding fences are attached to pre-set positions on the PCB board surface, corresponding to each voltage doubler rectifier unit, and fixed with high-temperature adhesive. S3. Thermally conductive insulating adhesive is evenly coated onto the outer surface of each voltage doubler rectifier unit, and cured after vacuum degassing. S4. An aluminum film shielding layer is plated onto the cured thermally conductive insulating adhesive layer. At the positions where the aluminum film shielding layer corresponds to the copper foil on the PCB board, flying wires are soldered to achieve electrical connection between the aluminum film and the copper foil. S5. A polyimide film is tightly wrapped around the outside of the aluminum film shielding layer. A single-sided pressure-sensitive adhesive film is applied to the overlapping ends of the polyimide film, and after compaction, the single-sided pressure-sensitive adhesive film completely covers the overlap seam. S6. The processed circuit board undergoes a 10,000-volt withstand voltage test and an EMC shielding effectiveness test to ensure it meets the requirements for use in electric flame stoves.

4. The processing technology for the EMC shielding structure of the voltage doubler rectifier circuit board according to claim 3, characterized in that, In step S6, the 10,000-volt withstand voltage test involves applying a test voltage to all voltage doubler rectifier units and continuously testing for more than 3,600 seconds. The test voltage is 1.5 times the normal operating voltage of the voltage doubler rectifier units.

5. The processing technology for the EMC shielding structure of the voltage doubler rectifier circuit board according to claim 3, characterized in that, In step S6, the specific method for EMC shielding effectiveness testing is as follows: (1) Assembly preparation: The voltage doubler rectifier circuit board to be tested is installed below the burner head of the electric flame stove. Each voltage doubler rectifier unit is individually electrically connected to the corresponding discharge device on the burner head. The assembled circuit board to be tested, together with the burner head, is placed into the microwave anechoic chamber; (2) Operating condition simulation: A working voltage is applied to the voltage doubler rectifier circuit board to make the discharge device work normally, simulating the actual operating conditions of the electric flame stove; (3) Signal acquisition: Abnormal signal data output by all voltage doubler rectifier units under different interference intensities are obtained through the signal receiving equipment in the microwave anechoic chamber; (4) Effectiveness judgment: The abnormal signal threshold collected is compared with the standard threshold, and the difference score is calculated. When the difference score is less than the preset qualified threshold, the EMC shielding effectiveness is judged to meet the standard.

6. An electric flame stove, characterized in that, The electric flame stove includes the EMC shielding structure of the voltage doubler rectifier circuit board as described in any one of claims 1 to 2.

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