Automatic power-on and power-off device for screening circuit boards

Abstract

The invention discloses an automatic power-on and power-off device for screening circuit boards. The automatic power-on and power-off device comprises a PLC (Programmable Logic Controller), a relay, an overcurrent protector and a direct-current stabilized power supply, the PLC can be used for programming according to a temperature circulation curve, setting starting and ending time of power-on and power-off and outputting a 5V level model; the relay has a direct-current 30V / 30A load capacity, and the working voltage of the relay is the same as that of the PLC; and the over-current protector is reset in a selected current by adopting a manual reset mode. In actual use, the USB power supply device is used for supplying power to the PLC and the relay, power-on and power-off time is set in the PLC according to a circuit board temperature circulation screening curve, the relay is changed from a normally-open state to a closed state at the time point needing power-on, so that the circuit board assembly is powered on, and the relay is normally-open and the circuit board assembly is powered off at the time point needing power-off; if a current abnormal problem occurs, the over-current protector is disconnected, and the circuit board assembly is powered off. The method is reliable, stable and low in cost.

Description

Technical Field

[0001] The invention belongs to the technical field of electrical control and relates to an automatic power on and off device for circuit board screening. Background Art

[0002] In the environmental stress screening of circuit boards, it is necessary to turn the power on and off according to the temperature curve. Under normal circumstances, the power on and off operations need to be completed by operators, but this method is labor-intensive and may miss the power-on time. At present, new models of products generally use automated testing to solve this problem, but for old products, it still needs to be done manually. In order to solve this problem, an automatic power on and off device for circuit board screening is designed and manufactured, which consists of a PLC control device, a relay, an overcurrent protector, and a DC power supply. Summary of the invention

[0003] (I) Purpose of the invention

[0004] The purpose of the present invention is to provide an automatic power on and off device for circuit board screening, which can output high / low level signals according to a set program using a PLC control device and realize voltage output through a relay, and add an overcurrent protector in the path to prevent current overload during the power-on process.

[0005] (II) Technical solution

[0006] In order to solve the above technical problems, the present invention provides an automatic power on and off device for circuit board screening, which includes: a PLC controller, a relay, an overcurrent protector, and a DC regulated power supply; the PLC controller is connected to the relay, the overcurrent protector is connected to the relay through a switch, the DC regulated power supply is connected to the relay and the circuit board assembly, and the overcurrent protector is connected to the circuit board assembly; a USB power supply device is used to power the PLC controller and the relay, and the power on and off time is set in the PLC controller according to the circuit board temperature cycle screening curve, and the relay is changed from normally open to closed at the time point when power is required, and the circuit board assembly is powered on, and the relay is made normally open at the time point when power is required to be powered off, and the circuit board assembly is powered off; when the current is abnormal, the overcurrent protector is disconnected, and the circuit board assembly is powered off.

[0007] Among them, the PLC controller is programmed according to the temperature cycle curve, the start and end time of power on and off are set, the power is supplied through the USB port, and the 5V level model is output.

[0008] Among them, the relay has a load capacity of DC 30V / 30A and an operating voltage of 5V, which is the same as the PLC controller. The relay is triggered at a high level or a low level by setting a jumper.

[0009] Among them, the overcurrent protector adopts manual reset mode, and the actual current can be reset within the selected current.

[0010] Among them, the overcurrent protector includes multiple specifications such as 3A, 5A, and 10A.

[0011] The output end of the overcurrent protector is connected to the positive pole of the power supply of the circuit board assembly, and the power supply ground of the circuit board assembly is connected to the ground of the DC regulated power supply.

[0012] Among them, the use process of the automatic power on and off device is:

[0013] (1) Connect the 5V and 5V ground of the PLC controller and relay to the USB power supply device;

[0014] (2) Connect the signal ground of the PLC controller to the 5V ground;

[0015] (3) Connect the PLC controller control signal to the relay control signal;

[0016] (4) Connect the relay input terminal to the positive connection of the DC regulated power supply;

[0017] (5) Connect the output end of the relay to the input end of the overcurrent protector through a key switch; connect multiple overcurrent protectors of different currents through multiple switches, close the switch when using a circuit, and disconnect it when not in use;

[0018] (6) Connect the output terminal of the overcurrent protector to the positive power supply of the circuit board assembly;

[0019] (7) Connect the power ground of the DC regulated power supply to the power ground of the circuit board assembly;

[0020] (8) Setting the power-on and power-off times in the PLC controller in sequence according to the temperature cycle curve and storing the program;

[0021] (9) Place the circuit board assembly into a temperature test chamber and set a temperature cycle curve in the temperature test chamber controller;

[0022] (10) While the temperature test chamber is running the temperature cycle curve, the DC regulated power supply switch and the USB control device switch are turned on simultaneously, and the program is run in the PLC controller;

[0023] (11) The PLC controller outputs a high-level signal at the time when power is required according to the set program. After receiving the high-level signal, the relay changes from normally open to closed, and the circuit board assembly is powered on. At the time when power is required to be cut off, the PLC controller does not output a signal, the relay is normally open, and the circuit board assembly is powered off;

[0024] (12) If an abnormal current problem occurs, the overcurrent protector is disconnected and the circuit board assembly is powered off.

[0025] (III) Beneficial effects

[0026] The automatic power on and off device for circuit board screening provided by the above technical solution can realize automatic power on and off during the circuit board temperature cycle screening process. The device has a DC load capacity of 30V / 30A, which can basically cover the power supply requirements of conventional circuit boards. In addition, the device has an overcurrent protection device to prevent the circuit board from burning due to excessive current, saving labor costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The figure is a connection diagram of the automatic power on and off device for circuit board screening of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, content and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples.

[0029] Reference Figure 1 As shown, the automatic power on and off device for circuit board screening in this embodiment includes a PLC controller, a relay, an overcurrent protector, and a DC regulated power supply; the PLC controller is connected to the relay, the overcurrent protector is connected to the relay through a switch, the DC regulated power supply is connected to the relay and the circuit board assembly, and the overcurrent protector is connected to the circuit board assembly; a USB power supply device (5V) is used to power the PLC controller and the relay, and the power on and off time is set in the PLC controller according to the circuit board temperature cycle screening curve, and the relay is changed from normally open to closed at the time point when power is required, so as to power on the circuit board assembly, and the relay is made normally open at the time point when power is required to be cut off, and the circuit board assembly is powered off; if an abnormal current problem occurs, the overcurrent protector is disconnected, and the circuit board assembly is powered off.

[0030] The PLC controller can be programmed according to the temperature cycle curve to set the start and end time of power on and off. It can be powered by a USB port and can output a 5V level model.

[0031] The relay has a load capacity of DC 30V / 30A, which can cover the power supply requirements of existing circuit boards. The relay operating voltage is also 5V, the same as the PLC controller, to achieve compatibility. The relay can be set to high or low level through a jumper.

[0032] The overcurrent protector adopts manual reset mode, that is, the actual current can be reset within the selected current. The overcurrent protector includes various specifications such as 3A, 5A, 10A, etc. The generally selected specification is 1.5 times the rated current. In addition, the greater the difference between the abnormal current and the selected current, the easier it is for the overcurrent protector to disconnect. In particular, there are differences in current during the high and low temperature screening process of the circuit board. Therefore, various factors should be fully considered, including the rated current and abnormal current at high and low temperatures.

[0033] In actual use, a USB power supply device (5V) is used to power the PLC controller and the relay. The PLC controller can set the power-on and power-off time according to the circuit board temperature cycle screening curve. At the time point when power is required, the PLC outputs a high-level signal (5V) and sends it to the relay. The input end of the relay is connected to the positive power supply of the DC voltage-stabilized power supply. The relay is a normally open type. After receiving the high-level signal, the relay is energized, and the output end of the relay outputs a voltage. The output end of the relay is connected to the input end of the overcurrent protector through a switch. According to the needs, the output end of the relay can be connected to multiple overcurrent protectors (different selected currents). When the current is required, the switch of which circuit is closed. The output end of the overcurrent protector is connected to the positive power supply of the circuit board assembly, and the power ground of the circuit board assembly is connected to the DC voltage-stabilized power ground. In the PLC controller, the power-on and power-off time are set in sequence according to the temperature cycle curve, and the program is stored; the circuit board assembly is placed in a temperature test chamber, and the temperature cycle curve is set in the temperature test chamber controller. While the temperature cycle curve is running in the temperature test chamber, the DC voltage-stabilized power supply switch and the USB control device switch are turned on synchronously, and the program is run in the PLC controller. The PLC controller follows the set program to change the relay from normally open to closed at the time when power is required, thereby powering on the circuit board assembly, and to normally open the relay at the time when power is required to power off, thereby powering off the circuit board assembly. If an abnormal current problem occurs, the overcurrent protector is disconnected and the circuit board assembly is powered off.

[0034] The method of using the automatic power on / off device for circuit board screening in this embodiment is as follows:

[0035] (1) Connect the 5V and 5V ground of the PLC controller and relay to the USB power supply device.

[0036] (2) Connect the signal ground of the PLC controller to the 5V ground.

[0037] (3) Connect the PLC controller control signal to the relay control signal.

[0038] (4) Connect the relay input terminal to the positive terminal of the DC regulated power supply.

[0039] (5) Connect the output end of the relay to the input end of the overcurrent protector through a key switch. Here, multiple switches can be used to connect multiple overcurrent protectors with different currents. The overcurrent protectors include various specifications such as 3A, 5A, and 10A. Generally, the selected specification is 1.5 times the rated current. In addition, the greater the difference between the abnormal current and the selected current, the easier it is for the overcurrent protector to disconnect. In particular, there are differences in current during the high and low temperature screening of the circuit board. Therefore, various factors should be fully considered, including the rated current and abnormal current under high and low temperature conditions. When using a circuit, close the switch and disconnect it when it is not used.

[0040] (6) Connect the output terminal of the overcurrent protector to the positive power supply of the circuit board assembly.

[0041] (7) Connect the power ground of the DC regulated power supply to the power ground of the circuit board assembly.

[0042] (8) Setting the power-on and power-off times in the PLC controller in sequence according to the temperature cycle curve and storing the program;

[0043] (9) Place the circuit board assembly into a temperature test chamber and set a temperature cycle curve in the temperature test chamber controller.

[0044] (10) While the temperature test chamber is running the temperature cycle curve, the DC regulated power supply switch and the USB control device switch are turned on simultaneously, and the program is run in the PLC controller.

[0045] (11) The PLC controller outputs a high-level signal at the time when power is required according to the set program. After receiving the high-level signal, the relay changes from normally open to closed, thereby powering on the circuit board assembly. When power is required to be cut off, the PLC controller does not output a signal, the relay is normally open, and the circuit board assembly is powered off.

[0046] (12) If an abnormal current problem occurs, the overcurrent protector is disconnected and the circuit board assembly is powered off.

[0047] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. An automatic power on / off device for circuit board screening, characterized in that: include: PLC controller, relay, overcurrent protector, DC regulated power supply; The PLC controller is connected to the relay, the overcurrent protector is connected to the relay through a switch, the DC regulated power supply is connected to the relay and the circuit board assembly, and the overcurrent protector is connected to the circuit board assembly; the PLC controller and the relay are powered by a USB power supply device, and the power-on and power-off time is set in the PLC controller according to the circuit board temperature cycle screening curve, and the relay is changed from normally open to closed at the time point when power is required to be supplied, and the circuit board assembly is powered on, and the relay is normally open at the time point when power is required to be powered off, and the circuit board assembly is powered off; when the current is abnormal, the overcurrent protector is disconnected, and the circuit board assembly is powered off.

2. The automatic on / off device for circuit board screening according to claim 1, characterized in that: The PLC controller is programmed according to the temperature cycle curve, the start and end time of power on and off are set, power is supplied through the USB port, and the output is a 5V level model.

3. The automatic on / off device for circuit board screening as claimed in claim 2, characterized in that: The relay has a DC 30V / 30A load capacity and an operating voltage of 5V, the same as the PLC controller. The relay is triggered at a high or low level by setting a jumper.

4. The automatic on / off device for circuit board screening as claimed in claim 3, characterized in that: The overcurrent protector adopts manual reset mode, and can be reset when the actual current is within the selected current.

5. The automatic on / off device for circuit board screening as claimed in claim 4, characterized in that: The overcurrent protector includes 3A, 5A, and 10A specifications.

6. The automatic on / off device for circuit board screening as claimed in claim 5, characterized in that: The output end of the overcurrent protector is connected to the positive pole of the power supply of the circuit board assembly, and the power supply ground of the circuit board assembly is connected to the ground of the DC regulated power supply.

7. The automatic on / off device for circuit board screening as claimed in claim 6, characterized in that: The use process of the automatic power on and off device is as follows: (1) Connect the 5V and 5V ground of the PLC controller and relay to the USB power supply device; (2) Connect the signal ground of the PLC controller to the 5V ground; (3) Connect the PLC controller control signal to the relay control signal; (4) Connect the relay input terminal to the positive connection of the DC regulated power supply; (5) Connect the output end of the relay to the input end of the overcurrent protector through a key switch; connect multiple overcurrent protectors of different currents through multiple switches, close the switch when using a circuit, and disconnect it when not in use; (6) Connect the output terminal of the overcurrent protector to the positive power supply of the circuit board assembly; (7) Connect the power ground of the DC regulated power supply to the power ground of the circuit board assembly; (8) Setting the power-on and power-off times in the PLC controller in sequence according to the temperature cycle curve and storing the program; (9) Place the circuit board assembly into a temperature test chamber and set a temperature cycle curve in the temperature test chamber controller; (10) While the temperature test chamber is running the temperature cycle curve, the DC regulated power supply switch and the USB control device switch are turned on simultaneously, and the program is run in the PLC controller; (11) The PLC controller outputs a high-level signal at the time when power is required according to the set program. After receiving the high-level signal, the relay changes from normally open to closed, and the circuit board assembly is powered on. At the time when power is required to be cut off, the PLC controller does not output a signal, the relay is normally open, and the circuit board assembly is powered off; (12) If an abnormal current problem occurs, the overcurrent protector is disconnected and the circuit board assembly is powered off.

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