Corrosion detection circuit, printed circuit board and switching power supply

Abstract

The utility model discloses a corrosion detection circuit, a printed circuit board and a switching power supply. The corrosion detection circuit is applied to the printed circuit board and comprises a first divider resistor, a voltage output port and a plurality of detection resistors, the detection resistors are connected in parallel, and a resistance welding window is arranged on a branch corresponding to each detection resistor; the first parallel connection end of each detection resistor is connected with the first end of the first divider resistor; one of the second parallel connection end of each detection resistor and the second end of the first divider resistor is used for connecting a power supply, and the other is used for grounding; the voltage output port is connected with the first end of the first divider resistor; the voltage output port is used for outputting a sensing value. According to the utility model, the corrosion condition of the printed circuit board can be accurately obtained, and the corrosion detection accuracy is improved.

Description

Technical Field

[0001] This utility model belongs to the field of electronic circuit technology, and in particular relates to a corrosion detection circuit, a printed circuit board, and a switching power supply. Background Technology

[0002] When uninterruptible power supplies (UPS) and converters operate in complex environments such as humidity, air pollution, and dust, moisture in the environment will condense into water droplets or form a liquid film on the printed circuit board (PCB) inside the equipment. Simultaneously, the air intake and exhaust processes during equipment heat dissipation will also bring contaminants and dust into the equipment, causing them to accumulate on the PCB. Under the combined effects of moisture, contaminants, and dust, the PCB can corrode, interfering with the normal operation of the circuits and ultimately leading to equipment malfunction. Utility Model Content

[0003] This utility model provides a corrosion detection circuit, a printed circuit board, and a switching power supply to accurately obtain the corrosion status of the PCB board and improve the accuracy of corrosion detection.

[0004] The first aspect of this utility model provides a corrosion detection circuit applied to a printed circuit board. The corrosion detection circuit includes a first voltage divider resistor, a voltage output port, and multiple detection resistors.

[0005] Each detection resistor is connected in parallel, and a solder resist window is provided on the branch corresponding to each detection resistor;

[0006] The first parallel terminal of each detection resistor is connected to the first terminal of the first voltage divider resistor;

[0007] One of the second parallel terminals of each detection resistor and the second terminal of the first voltage divider resistor is used to connect to the power supply, and the other is used to ground.

[0008] The voltage output port is connected to the first end of the first voltage divider resistor; wherein, the voltage output port is used to output the sensed value.

[0009] In one embodiment, the corrosion threshold for the solder resist opening corresponding to each sensing resistor to break when subjected to corrosion is different.

[0010] In one embodiment, the wire diameter of the connecting wire at the solder resist opening corresponding to each sensing resistor is different.

[0011] In one embodiment, the solder resist openings corresponding to each detection resistor are placed in a centralized manner, and the resistance value of each detection resistor is the same.

[0012] In one embodiment, the corrosion detection circuit further includes at least one detection wire;

[0013] The first end of the detection wire is connected to the first parallel terminal, and the second end of the detection wire is close to the second parallel terminal and suspended.

[0014] Alternatively, the first end of the detection wire is connected to the second parallel terminal, and the second end of the detection wire is close to the first parallel terminal and suspended.

[0015] In one embodiment, the corrosion detection circuit further includes a second voltage divider resistor;

[0016] The second parallel terminal is connected to the power supply or ground through the second voltage divider resistor.

[0017] In one embodiment, the corrosion detection circuit further includes a capacitor;

[0018] The capacitor is connected between the first parallel terminal and the second parallel terminal.

[0019] A second aspect of this utility model provides a printed circuit board including the corrosion detection circuit described in the first aspect or any embodiment of the first aspect.

[0020] A third aspect of this utility model provides a switching power supply including a heat dissipation channel and a printed circuit board as described in the second aspect above;

[0021] The corrosion detection circuit of the printed circuit board is located in the heat dissipation channel, and the distance between the corrosion detection circuit and the air inlet of the heat dissipation channel is greater than a preset length.

[0022] In one embodiment, the switching power supply further includes a display device;

[0023] The display device is used to display the corrosion result corresponding to the sensing value output by the corrosion detection circuit.

[0024] The beneficial effects of this utility model embodiment compared with the prior art are:

[0025] By connecting multiple detection resistors in parallel and then in series with a first voltage divider resistor in the corrosion detection circuit, and setting solder mask openings on the parallel branches of each detection circuit, corrosion detection can be achieved by utilizing the corrosion status of each solder mask opening. Specifically, when a solder mask opening is corroded, the corresponding detection resistor becomes open-circuited in the corrosion detection circuit. The resistance value of all detection resistors connected in parallel in the corrosion detection circuit will change, and the voltage value output from the voltage output port will also change accordingly. This allows for accurate acquisition of the specific corrosion status of the circuit board, improving the accuracy of corrosion detection. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this utility model, 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 this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a first circuit structure diagram of the corrosion detection circuit provided in the embodiments of this application;

[0028] Figure 2 This is a second circuit structure diagram of the corrosion detection circuit provided in the embodiments of this application;

[0029] Figure 3 This is a first schematic diagram of the corrosion detection circuit for detecting wet dust corrosion provided in an embodiment of this application;

[0030] Figure 4 This is an equivalent circuit diagram of the corrosion detection circuit provided in the embodiments of this application for detecting wet dust corrosion;

[0031] Figure 5 This is a third circuit structure diagram of the corrosion detection circuit provided in the embodiments of this application;

[0032] Figure 6 This is a fourth circuit structure diagram of the corrosion detection circuit provided in the embodiments of this application;

[0033] Figure 7 This is the fifth circuit structure diagram of the corrosion detection circuit provided in the embodiments of this application;

[0034] Figure 8 This is a second schematic diagram of the corrosion detection circuit for detecting wet dust corrosion provided in the embodiments of this application;

[0035] Figure 9 This is the sixth circuit structure diagram of the corrosion detection circuit provided in the embodiments of this application;

[0036] Figure 10 This is the seventh circuit structure diagram of the corrosion detection circuit provided in the embodiments of this application;

[0037] Figure 11 This is a third schematic diagram of the corrosion detection circuit provided in this application for detecting wet dust corrosion. Detailed Implementation

[0038] To enable those skilled in the art to better understand this solution, the technical solutions in the embodiments of this solution will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this solution, not all of them. Based on the embodiments of this solution, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this solution.

[0039] The term "comprising" and any other variations thereof in the specification, claims, and accompanying drawings of this invention mean "including but not limited to," and are intended to cover a non-exclusive inclusion, not limited to the examples listed herein. Furthermore, the terms "first" and "second," etc., are used to distinguish different objects, not to describe a specific order.

[0040] The inventors have discovered that, in order to perform corrosion detection on PCB boards, the high or low level output of the corrosion detection circuit is usually used for judgment. However, this method can only simply determine whether the PCB board has been corroded, and cannot accurately obtain the specific situation of corrosion on the PCB board.

[0041] Based on the idea of ​​accurately detecting corrosion on the circuit board, in the embodiments of this application, multiple detection resistors are connected in parallel and then connected in series with the first voltage divider resistor. Solder mask openings are set on the parallel branches of each detection circuit. When the solder mask openings are corroded, the equivalent resistance values ​​of all detection resistors will change, which will cause the sensing value output by the voltage output port to change accordingly. Thus, the corrosion status on the PCB board can be accurately obtained through the change in sensing value.

[0042] The implementation of this utility model will be described in detail below with reference to the specific accompanying drawings:

[0043] See Figure 1 and Figure 2 This utility model provides a corrosion detection circuit for use on a printed circuit board. The corrosion detection circuit includes a first voltage divider resistor Rf1, a voltage output port OUT, and multiple detection resistors Ri. The value of i can be 1, 2, 3...n, where n is a positive integer.

[0044] Each sensing resistor Ri is connected in parallel, and a solder resist window Bi is set on the branch corresponding to each sensing resistor Ri. The value of i is also 1, 2, 3...n, and the solder resist window corresponds to the corresponding sensing resistor, that is, sensing resistor R1 corresponds to solder resist window B1, and sensing resistor R2 corresponds to solder resist window B2.

[0045] Here, "solder mask opening" refers to creating a window in the PCB trace within a predetermined area on the branch corresponding to the detection resistor Ri, without applying protective coating, thus creating a weak point. Areas with solder mask openings are more susceptible to corrosion. When the solder mask opening is corroded, an open circuit forms at the corresponding detection resistor, causing a change in the equivalent resistance of the detection resistor connected in the circuit, thereby enabling corrosion detection of the PCB board.

[0046] The first parallel terminal of each sensing resistor Ri is connected to the first terminal of the first voltage divider resistor Rf1; one of the second parallel terminals of each sensing resistor Ri and the second terminal of the first voltage divider resistor Rf1 is used to connect to the power supply VCC, and the other is used to ground GND.

[0047] When the second terminal of the first voltage divider resistor Rf1 is connected to the power supply VCC, the first voltage divider resistor Rf1 acts as a pull-up resistor, specifically as follows: Figure 1 As shown. When the second terminal of the first voltage divider resistor Rf1 is grounded to GND, the first voltage divider resistor Rf1 acts as a pull-down resistor, specifically as follows. Figure 2 As shown.

[0048] The voltage output port OUT is connected to the first terminal of the first voltage divider resistor Rf1; wherein, the voltage output port OUT is used to output the sensed value.

[0049] Here, the voltage output port OUT can output a corresponding sensing value based on the detected corrosion. This sensing value is generally the voltage value corresponding to the equivalent resistance mentioned above.

[0050] by Figure 1 For example, the more severe the corrosion of the PCB board, the more detection circuits cannot be connected to the circuit, and the larger the equivalent resistance value of the circuit, the larger the corresponding voltage drop and the higher the sensed value.

[0051] This embodiment of the invention connects multiple detection resistors in parallel in a corrosion detection circuit and then connects them in series with a first voltage divider resistor. Solder mask openings are provided on the parallel branches of each detection circuit. Corrosion detection can be achieved by utilizing the corrosion status of each solder mask opening. When a solder mask opening is corroded, the corresponding detection resistor becomes open-circuited in the corrosion detection circuit. The resistance value of all the detection resistors connected in parallel in the corrosion detection circuit changes, and the voltage output value at the voltage output port also changes accordingly. This allows for accurate acquisition of the specific corrosion status of the circuit board, improving the accuracy of corrosion detection.

[0052] Dust in the environment may contain soluble salts such as chlorides, sulfates and nitrates. When the ambient humidity increases, moisture will form an adsorbed liquid film on the surface of the PCB board. These salts will also dissolve in it, forming a conductive electrolyte solution, which will cause corrosion to the circuit board and form a corrosion equivalent resistance, namely wet dust corrosion.

[0053] When the corrosion equivalent resistance is small, the resistance value of the corrosion equivalent resistance can be ignored, that is, the wet dust is equivalent to a wire, which may cause a short circuit in the circuit.

[0054] Optional, see Figure 3 and Figure 4 The detection resistors Ri can be placed together. The detection resistors Ri may be connected by wet dust, causing a short circuit, or a corrosion equivalent resistor may be connected in the circuit (when the resistance of the corrosion equivalent resistor is large, the wet dust cannot be ignored).

[0055] like Figure 3 Wet dust corrosion occurs between sensing resistors R1 and R2, meaning an equivalent corrosion resistance Rx is connected between the first and second parallel terminals. The corresponding equivalent circuit diagram can be found in [reference needed]. Figure 4 When the corrosion equivalent resistance Rx is negligible, a short circuit will occur, causing a change in the sensed value output by the voltage output port OUT.

[0056] When the corrosion equivalent resistance is not negligible, it's equivalent to adding another resistor in parallel at the sensing resistor Ri, causing a change in the resistance values ​​of all parallel resistors. The sensed value output from the voltage output port OUT will also change accordingly.

[0057] In some embodiments, the corrosion threshold for the solder resist window Bi corresponding to each detection resistor Ri to break when subjected to corrosion is different.

[0058] In this embodiment, in order to more accurately detect the degree of corrosion on the PCB board, different corrosion thresholds can be set for each solder mask opening Bi.

[0059] Here, a low corrosion threshold means that corrosion will open a circuit when the corrosion is relatively mild; a high corrosion threshold means that corrosion will open a circuit when the corrosion is more severe.

[0060] When corrosion occurs on the PCB board (for example, the degree of corrosion is A), due to the different corrosion thresholds corresponding to the solder mask openings Bi, the corrosion on the PCB board will cause the solder mask openings Bi with corrosion thresholds less than A to be corroded and broken, forming an open circuit at the corresponding detection resistor, thereby changing the corresponding equivalent resistance. The sensing value output by the voltage output port OUT will also change accordingly, so the degree of corrosion on the PCB board can be accurately obtained through the sensing value.

[0061] Optionally, the corrosion threshold corresponding to the solder mask opening Bi of each detection resistor Ri may be different. This could be due to different wire diameters of the connecting wires at the solder mask opening Bi of each detection resistor Ri, different materials of the connecting wires at the solder mask opening Bi of each detection resistor Ri, or different degrees of solder mask layer removal at the solder mask opening Bi of each detection resistor Ri.

[0062] Furthermore, the solder resist openings Bi corresponding to each detection resistor Ri are placed in a centralized manner, and the resistance value of each detection resistor Ri is the same.

[0063] In this embodiment, by setting each detection resistor Ri to the same resistance value, it is possible to quickly and accurately determine how many detection resistors Ri are not connected to the circuit, thereby determining how many solder mask openings Bi are open, and thus quickly and accurately judging the corrosion status at that location on the circuit board.

[0064] When only one solder mask opening (Bi) experiences open corrosion, the corrosion at that location on the PCB is relatively minor and can be classified as mild corrosion. When multiple solder mask openings (Bi) experience open corrosion, the corrosion intensifies and can be classified as severe corrosion. When a large number of solder mask openings (Bi) experience open corrosion, severe corrosion occurs on the PCB and can be classified as heavy corrosion.

[0065] In other embodiments, the solder mask openings Bi corresponding to each detection resistor Ri can be distributed at different locations on the PCB board, and the resistance value of each detection resistor Ri is different, so that the corrosion situation at different locations on the PCB board can be detected and the range of corrosion on the PCB board can be obtained.

[0066] Here, by precisely selecting the resistance values ​​of each detection resistor Ri, the detection resistor Ri that is connected to or not connected to the circuit when the equivalent resistance values ​​of each detection resistor Ri are different can be accurately determined, thereby determining which location on the PCB board has an open circuit due to corrosion and obtaining the range of corrosion on the PCB board.

[0067] In some embodiments, such as Figure 5 As shown, the corrosion detection circuit also includes capacitor C1; capacitor C1 is connected between the first parallel terminal and the second parallel terminal.

[0068] In this embodiment, capacitor C1 can be used to achieve anti-jitter and filtering functions to ensure the stability of the output sensing value.

[0069] Here, a reference output port OUT' can also be set. The corrosion status on the PCB board can be obtained through the voltage output port OUT and the reference output port OUT'.

[0070] In some specific embodiments, such as Figure 6As shown, the following example illustrates the setting of three sensing resistors. The second terminal of the first voltage divider resistor Rf1 is connected to the power supply VCC, and the resistance of the first voltage divider resistor Rf1 is 3KΩ. The resistances of sensing resistors R1, R2, and R3 are all 5.1KΩ, and the voltage of the power supply VCC is 3.3V.

[0071] When the three solder mask openings B1, B2 and B3 are not disconnected, the sensing resistors R1, R2 and R3 are connected in parallel, and the 3.3V voltage is divided to ground. The sensed value output by the voltage output port OUT is 1.19V.

[0072] When one of the three solder mask openings is open and the other two are not open, the two sensing resistors corresponding to the unopened solder mask opening are connected in parallel, and the 3.3V voltage is divided to ground. The sensed value output by the voltage output port OUT is 1.52V.

[0073] When two of the three solder resist openings are open and the third solder resist opening is not open, the detection resistor corresponding to the unopened solder resist opening is connected in parallel, and the 3.3V voltage is divided to ground. The sensed value output by the voltage output port OUT is 2.08V.

[0074] When all three solder mask openings B1, B2 and B3 are disconnected, the sensing resistors R1, R2 and R3 are not connected to the circuit, there is no voltage drop between 3.3V and ground, and the sensed value output by the voltage output port OUT is 3.3V.

[0075] Furthermore, when wet dust corrosion occurs, the equivalent resistance of the corrosion in parallel at the sensing resistor may become short-circuited, reducing the equivalent resistance of all resistors except the first voltage divider resistor Rf0. Consequently, the sensed value output by the voltage output port OUT will decrease. If the aforementioned corrosion open-circuit condition does not exist, the sensed value output by the voltage output port OUT will be less than 1.19V.

[0076] Correspondingly, the corrosion situation can be judged as follows: when the sensing value output by the voltage output port OUT is in [0, 1.19V), it can be determined that wet dust corrosion has occurred on the PCB board.

[0077] When the sensed value of the voltage output port OUT is 1.19V and falls within the range of [1.19V, 1.52V), it can be considered that no corrosion has occurred on the PCB board; when the sensed value of the voltage output port OUT is within the range of [1.19V, 1.52V), it can be considered that the corrosion is mild; when the sensed value of the voltage output port OUT is within the range of [1.52V, 2.08V), it can be considered that the corrosion is moderate; when the sensed value of the voltage output port OUT is within the range of [2.08V, 3.3V), it can be considered that the corrosion is severe dust accumulation.

[0078] In the above embodiments, wet dust corrosion is mainly detected by detecting the branch corresponding to the detection resistor Ri. However, when the detection resistor Ri is not centrally located or is located in different positions, it is not easy to detect wet dust. Therefore, additional detection wires can be used to detect wet dust.

[0079] In some embodiments, such as Figure 7 As shown, the corrosion detection circuit also includes at least one detection wire Lj. The value of j can be 1, 2, 3...m.

[0080] The first end of the detection wire Lj is connected to the first parallel terminal, and the second end of the detection wire is close to the second parallel terminal and suspended.

[0081] Alternatively, the first end of the detection wire Lj is connected to the second parallel terminal, and the second end of the detection wire is close to the first parallel terminal and suspended.

[0082] In this embodiment, the first end of each detection wire Lj can be connected to the first parallel terminal or the second parallel terminal, and the second end is left floating. When there is wet dust corrosion, the wet dust can connect the second end to other positions in the corrosion detection circuit, and connect a corrosion equivalent resistor Rx, so that the resistance value of the equivalent resistance formed by the resistors other than the first voltage divider resistor Rf1 (i.e., the detection resistor Ri and the corrosion equivalent resistor Rx) changes, thereby changing the sensed value output by the voltage output port OUT.

[0083] For details, please refer to Figure 8 , Figure 8 The ellipse in the diagram represents the possible locations of wet dust. When any wet dust is present, there will be a corrosion equivalent resistance Rx connected in parallel with the detection resistance Ri. When the resistance of the corrosion equivalent resistance Rx is sufficiently small, it will cause the detection resistance Ri to short-circuit.

[0084] Optionally, the second end of each detection lead Li can be suspended at different positions close to the first or second parallel connection end in order to detect wet dust at different locations and ensure the accuracy of wet dust detection.

[0085] Optional, such as Figure 9 As shown, the corrosion detection circuit may include a first voltage divider resistor Rf1, a detection resistor R1, a detection lead L1, and a voltage output port OUT.

[0086] The first voltage divider resistor Rf1 and the sensing resistor R1 are connected in series between the power supply and the ground wire, and a solder resist window is provided on the series connection line.

[0087] One end of the detection wire L1 is connected to the connection point of the first voltage divider resistor Rf1 and the detection resistor R1, and the other end of the detection wire L1 is close to the other end of the detection resistor R1 and left floating. Alternatively, one end of the detection wire L1 is close to the connection point of the first voltage divider resistor Rf1 and the detection resistor R1 and left floating, and the other end of the detection wire L1 is connected to the other end of the detection resistor R1.

[0088] The aforementioned detection resistor R1, solder mask opening B1, and detection lead L1 can be used to perform simple and rapid detection of corrosion open circuits and wet dust corrosion on PCB boards.

[0089] Correspondingly, it is also possible to omit the solder mask opening corresponding to the detection resistor R1 and perform detection solely through the set detection wire L1, thereby enabling separate detection of wet dust corrosion on the PCB board.

[0090] For specific corrosion conditions and detection methods, please refer to the above embodiments, which will not be repeated here.

[0091] In some embodiments, such as Figure 10 As shown, the corrosion detection circuit also includes a second voltage divider resistor Rf2; the second parallel terminal is connected to the power supply VCC or ground GND through the second voltage divider resistor Rf2.

[0092] In this embodiment, a second voltage divider resistor Rf2 can also be connected in series in the corrosion detection circuit to limit the current and protect the components in the corrosion detection circuit.

[0093] Here, the first end of the detection wire Lj can be connected to either the first parallel terminal or the second parallel terminal, and the second end can be suspended near the second parallel terminal or suspended near the first parallel terminal.

[0094] In the above situation, when a short circuit is caused by wet dust corrosion, the detection resistor Ri is short-circuited. When the detection wire Lj is short-circuited, there are still first voltage divider resistors Rf1 and second voltage divider resistors Rf2 in the main circuit. The current in the circuit will not increase sharply, which can prevent damage to the components in the circuit.

[0095] In addition, see Figure 11 As shown, Figure 11 The ellipse in the diagram represents the location of possible wet dust. The first end of the detection wire Li can be connected to the first parallel terminal, and the second end can be suspended near the target endpoint. The target endpoint refers to the endpoint where the second voltage divider resistor Rf2 is connected to the power supply VCC or ground GND.

[0096] When a short circuit is caused by wet dust corrosion, both the sensing resistor Ri and the second voltage divider resistor Rf2 will be short-circuited. In this case, the sensed value output by the voltage output port OUT is different from the sensed value when only the sensing resistor Ri is short-circuited. Thus, the location of the short circuit caused by wet dust corrosion can be distinguished by the different positions of the different sensing wires Lj.

[0097] Correspondingly, the first end of the detection wire Lj can also be connected to the aforementioned target endpoint, and the second end of the detection wire Lj is suspended near the first parallel connection end.

[0098] This application also provides a circuit board and a switching power supply. For details not described in detail herein, please refer to the corresponding circuit embodiments described above.

[0099] In some embodiments, the printed circuit board may include the corrosion detection circuit as described in any of the above embodiments.

[0100] In some embodiments, the switching power supply may include a heat dissipation channel and a printed circuit board as described above; the corrosion detection circuit of the printed circuit board is located in the heat dissipation channel, and the distance between the corrosion detection circuit and the air inlet of the heat dissipation channel is greater than a preset length, so as to detect the degree of dust accumulation.

[0101] In one embodiment, the switching power supply further includes a display device; the display device is used to display the corrosion result corresponding to the sensing value output by the corrosion detection circuit.

[0102] Here, the display device can be a screen, on which the sensed values, corrosion status, and alarm information can be displayed. The display device can also be an alarm light, which can display different colors according to the corrosion status, such as green or off for no corrosion, yellow for light corrosion, orange for moderate corrosion, and red for severe corrosion; alternatively, different numbers of lights can be lit depending on the corrosion status, such as one red light for light corrosion, two red lights for moderate corrosion, and three red lights for severe corrosion, etc.

[0103] In addition, an alarm device can be installed. When corrosion occurs, the alarm device can sound an alarm and send the alarm information to relevant personnel.

[0104] The above-described embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A corrosion detection circuit, characterized in that, Applied to printed circuit boards, the corrosion detection circuit includes a first voltage divider resistor, a voltage output port, and multiple detection resistors; Each detection resistor is connected in parallel, and a solder resist window is provided on the branch corresponding to each detection resistor; The first parallel terminal of each detection resistor is connected to the first terminal of the first voltage divider resistor; One of the second parallel terminals of each detection resistor and the second terminal of the first voltage divider resistor is used to connect to the power supply, and the other is used to ground. The voltage output port is connected to the first end of the first voltage divider resistor; wherein, the voltage output port is used to output the sensed value.

2. The corrosion detection circuit according to claim 1, characterized in that, The corrosion threshold for the solder resist opening corresponding to each sensing resistor to break when corroded is different.

3. The corrosion detection circuit according to claim 2, characterized in that, The wire diameter of the connecting wire at the solder resist window corresponding to each detection resistor is different.

4. The corrosion detection circuit according to claim 2 or 3, characterized in that, The solder resist openings corresponding to each detection resistor are placed in a group, and the resistance value of each detection resistor is the same.

5. The corrosion detection circuit according to any one of claims 1 to 4, characterized in that, The corrosion detection circuit also includes at least one detection wire; The first end of the detection wire is connected to the first parallel terminal, and the second end of the detection wire is close to the second parallel terminal and suspended. Alternatively, the first end of the detection wire is connected to the second parallel terminal, and the second end of the detection wire is close to the first parallel terminal and suspended.

6. The corrosion detection circuit according to claim 5, characterized in that, The corrosion detection circuit also includes a second voltage divider resistor; The second parallel terminal is connected to the power supply or ground through the second voltage divider resistor.

7. The corrosion detection circuit according to any one of claims 1 to 4, characterized in that, The corrosion detection circuit also includes capacitors; The capacitor is connected between the first parallel terminal and the second parallel terminal.

8. A printed circuit board, characterized in that, It includes the corrosion detection circuit as described in any one of claims 1 to 7.

9. A switching power supply, characterized in that, Includes heat dissipation channels and a printed circuit board as described in claim 8 above; The corrosion detection circuit of the printed circuit board is located in the heat dissipation channel, and the distance between the corrosion detection circuit and the air inlet of the heat dissipation channel is greater than a preset length.

10. The switching power supply according to claim 9, characterized in that, Switching power supplies also include display devices; The display device is used to display the corrosion result corresponding to the sensing value output by the corrosion detection circuit.

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