How is the PCB impedance test measured?

In the general state of the conductor, there are some ways to prevent the flow of current, this effect is called impedance. The impedance of the PCB circuit is generally calculated by software. After the finished product, there is a special instrument for testing.

Impedance

In circuits with resistors, inductors, and capacitors, the blocking effect on the AC is called impedance. The impedance is usually represented by Z. The impedance consists of resistance, inductive reactance and capacitive reactance, but not the three are simply added. The unit of impedance is Europe. In direct current, the effect of an object on current obstruction is called resistance. All materials in the world have resistance, but the difference in resistance value. Substances with low electrical resistance are called good conductors, such as metals; materials with high electrical resistance are called insulators, such as wood and plastic. There is also a conductor between the two called a semiconductor, and a superconductor is a substance with a resistance value close to zero. However, in the field of alternating current, in addition to the resistance will block the current, the capacitance and inductance will also hinder the flow of current. This effect is called reactance, which means resisting the action of current. The reactances of capacitors and inductors are called capacitive reactance and inductive reactance, respectively, referred to as capacitive reactance and inductive reactance. Their unit of measurement is ohmic like the resistance, and the value of the value is related to the frequency of the alternating current. The higher the frequency, the smaller the capacitive reactance is, and the higher the frequency, the larger the capacitive reactance and the smaller the inductive reactance. In addition, the capacitive reactance and the inductive reactance also have a phase angle problem, and have a vector relationship, so it is said that the impedance is the sum of the resistance and the reactance in the vector. For a particular circuit, the impedance is not constant, but varies with frequency. In a series circuit of resistors, inductors, and capacitors, the impedance of the circuit is generally greater than the resistance. That is, the impedance is reduced to a minimum. In an inductive and capacitive parallel circuit, the impedance increases to a maximum value during resonance, which is the opposite of a series circuit.

TDR testing is currently used primarily for PCB circuit boards in battery circuit boards. Signal lines and device impedance tests.

There are many reasons for affecting the accuracy of TDR test, mainly reflection, calibration, reading selection, etc. Reflex will cause serious deviation of the short PCB signal line test value, especially obvious in the case of using TIP (probe) to test. because the TIP and signal line contact points cause a large impedance discontinuity, the reflection occurs, and the impedance curve of the PCB signal line in the vicinity of three or four inches is fluctuating.

Such as single-ended signal lines, differential signal lines, connectors and so on. There is a requirement for this kind of test, which is combined with the conditions of the actual application. For example, the rising edge of the signal line of the actual signal line is about 300ps, then the rising edge of the output pulse signal of the TDR should be set at around 300ps instead of 30ps. The rising edge of the left and right, otherwise the test results may be quite different from the actual application.

Communication products or some industrial products will often encounter impedance requirements. The type of impedance requirements seems to be divided into single-ended impedance and differential impedance. In addition, customers generally propose impedance tolerances, such as requiring impedance tolerance range +/- 10%. As for the role of impedance, it is not related to your career in selling PCB. This problem is best to ask the customer's engineer. My understanding of the impedance should be to avoid the signal transmission changes as much as possible in the appropriate range. for reference only.

Their unit of measurement is ohmic like the resistance, and the value of the value is related to the frequency of the alternating current. The higher the frequency, the smaller the capacitive reactance is, and the higher the frequency, the larger the capacitive reactance and the smaller the inductive reactance. In addition, the capacitive reactance and the inductive reactance also have a phase angle problem, and have a vector relationship, so it is said that the impedance is the sum of the resistance and the reactance in the vector. For a particular circuit, the impedance is not constant, but varies with frequency. In a series circuit of resistors, inductors, and capacitors, the impedance of the circuit is generally greater than the resistance. That is, the impedance is reduced to a minimum. In an inductive and capacitive parallel circuit, the impedance increases to a maximum value during resonance, which is the opposite of a series circuit.

In circuits with resistors, inductors, and capacitors, the blocking effect on the AC is called impedance. The impedance is usually represented by Z. The impedance consists of resistance, inductive reactance and capacitive reactance, but not the three are simply added. The unit of impedance is Europe. In direct current, the effect of an object on current obstruction is called resistance. All materials in the world have resistance, but the difference in resistance value. Substances with low electrical resistance are called good conductors, such as metals; materials with high electrical resistance are called insulators, such as wood and plastic. There is also a conductor between the two called a semiconductor, and a superconductor is a substance with a resistance value close to zero. However, in the field of alternating current, in addition to the resistance will block the current, the capacitance and inductance will also hinder the flow of current. This effect is called reactance, which means resisting the action of current. The reactances of capacitors and inductors are called capacitive reactance and inductive reactance, respectively, referred to as capacitive reactance and inductive reactance.

PATT CIRCUITS produces high quality impedance control PCB for customers all over the world, is a leading impedance control PCB manufacturer supplier.