What are the factors that affect the leakage current of PCB?

Humidity, voltage, temperature, and moisture.

voltage, when the voltage is higher, the greater the leakage current generated;

frequency, the higher the frequency, the stronger the penetrating ability, and the greater the leakage;

Humidity, humidity is large, there are many water molecules, they have a strong ability to carry ions in the air, and they have a strong conductivity on the ground, which will increase the leakage;

Insulation performance, wire support and insulation performance of protective materials are the main factors affecting the leakage;

Sharp horn hair, in these locations, is prone to generate charge concentration, forming a high voltage, so it affects the magnitude of the leakage current.

The leakage current of transistors and other components is no longer within the scope of this issue.

1.The influence of different test lines.

2.The effect of the high-end leads.

When the micro-ampere meter is located at the high-voltage end, when the microphone shielded wire is used as the high-voltage lead, the leakage current on its outer surface is shielded and does not flow through the micro-ampere meter and the ampere meter, so there is no measurement error, otherwise a large error will be generated. When the microampere is located at the low voltage end. The use of shielded wire has no effect, at this time, the lead wire connected to the tested cable, when its electric field strength (depending on the diameter and shape of the wire) is greater than 20kV cm, the air along the surface of the wire swims; There is a certain leakage current to the ground and flows through the microampere meter, which affects the accuracy of the test results.

The improvement method is to increase the diameter of the high-voltage lead, shorten the length, reduce its surface burr and increase the distance to the ground.

3.The effect of temperature.

The voltage and resistance can be changed in DC circuits, and the resistance, inductance, capacitance, and frequency can be changed in AC circuits.

The greater the power of a household appliance, the lower the resistance. The resistance of the conductor is a property of the conductor itself, and its size depends on the material, cross-sectional area, length, and temperature of the conductor

The larger the cross-sectional area, the smaller the resistance.

The longer the length, the greater the resistance.

There are so many situations that the point is to know what kind of results you want to get under what conditions, at least you have to know AC and DC.

The current in the circuit is directly proportional to the voltage across the conductor and inversely proportional to the resistance of the conductor.

The magnitude of the voltage in the circuit is related to the voltage provided by the power supply;

The voltage of the electrical appliance is related to the resistance of the electrical appliance that divides the voltage;

The voltage is actually the potential difference, and only the charged body itself is affected by the potential difference, and the current is actually determined by voltage and resistance at the same time.

But it can also be determined by the total amount of electricity passed per unit of time.

The induced current is related to the length of the wire, the cutting speed, and the magnetic induction strength of the magnetic field. 1.Keep the length and magnetic field of the wire cutting part unchanged, select different cutting speeds, and record the current size separately.

2.Keep the cutting speed and magnetic field unchanged, select the cutting length that is not passable, and the probability of current is magnitude. 3.

Keep the length and speed constant, and select different magnetic induction strengths to determine the probability of current. Analyzing the data, it should be possible to obtain that the magnitude of the current is proportional to the length, the speed is also proportional, and the magnetic induction intensity is proportional.

The direction in which the induced current is affected by the direction of coil rotation and the direction of the magnetic field. Generally speaking, when a part of the conductor of the closed loop moves in the magnetic field to cut the magnetic inductance line, the magnetic flux in the closed loop will change, and the induced electromotive force will be generated in the closed loop, thus generating an electric current, which is called induced current.

Factors that affect the size.

the speed at which the wire is cut;

the direction of the speed of the wire cutting;

the strength of the permanent magnet;

the number of wires cut;

The effective length of the cut wire.

Induced EMF formula: according to Faraday's law of electromagnetic induction: e=blvsin ( is the angle between b and v).

When the conductor is stationary in the magnetic field or moves parallel to the magnetic inductance lines, the magnetic flux does not change, so no current is induced in the closed loop, no matter how strong the magnetic field is.

The magnitude of the induced current is proportional to the magnetic induction intensity b, the length of the wire l, the speed of motion v, and the sine of the angle between the direction of motion and the direction of the magnetic inductance line. Increasing the magnetic induction intensity B, increasing the length of the wire L of the cutting magnetic inductance line, increasing the cutting speed v and cutting the magnetic inductance line as perpendicular as possible (=90°) can increase the induced current.

Note: To increase the cutting speed, theoretically the higher the speed, the better, but due to the large inertia of the meter pointer (especially for large demonstration meters), when the cutting speed is too large, the pointer will not have time to respond, and the induced current shown by calling the meter will be reduced. Therefore.

Attention should be paid to selecting the appropriate cutting speed to achieve a better demonstration effect.

In the electromagnetic induction phenomenon, the factor that affects the size of the induced current, in addition to the speed of the movement of the bar magnet relative to the coil, another factor is the number of coils of the wire in the coil, the number of loops is more than 1 times, the induced current generated is 1 times larger, on the contrary, if the number of turns is reduced, the induced current will also be proportionally reduced.

The magnitude factors that affect the magnetic generation are the number of ties of the coil. Magnitude of magnetic flux. and the speed at which a closed line travels through a magnetic field.

Factors that affect the magnitude of a conductor's resistance.

Answer: Factors affecting the size of resistance: material, length, cross-sectional area, temperature (1) Material: conductors of different materials, the resistance is generally different (2) Length: the same material, the same thickness of the conductor, the longer the length, the greater the resistance; The shorter the length, the smaller the resistance;

3) Cross-sectional area: the larger the cross-sectional area of the conductor of the same material and the same length, the smaller the resistance; The smaller the cross-sectional area, the greater the resistance;

4) Temperature: When all other factors are the same, in general, the resistance becomes larger when the temperature rises, and the resistance becomes smaller when the temperature decreases