The composition of integrated circuits continues to evolve. In the circuit, transistors, capacitors, resistors, and active and passive components need to be integrated on tiny semiconductor wafers and installed using integrated circuits (ICs), which use certain processing methods and follow specific Circuit connection. It is transformed into a local structure inside the container that can perform some circuit or system function.
Early integrated circuits used electron tubes, and later transistors. The electronic components of integrated circuits are growing exponentially and moving toward miniaturization. The daily use of powder metallurgy electronics is often affected by damage to integrated circuits, resulting in the failure of one or more components. So how to determine the quality of integrated circuits?
(1) Off-road measurement method. The off-circuit measurement method calculates the DC resistance value of the integrated circuit when it is not soldered into the circuit by comparing it with the known DC resistance value between the pins of a conventional integrated circuit of the same model to determine whether it is normal.
(2)On-road measurement method. The voltage measurement method, resistance measurement method and current measurement method used in the in-circuit measurement method determine whether the integrated circuit is damaged by measuring the voltage value, resistance value and current value of each pin of the integrated circuit on the circuit.
(3) Voltage detection method. By detecting the pin voltage value of the integrated circuit and comparing it with the relevant reference value, it is possible to determine whether the integrated circuit has a fault and the cause of the fault.
The reference data and detection data used in the voltage detection method are two different forms of data. The resistance detection method measures the forward and reverse DC resistance values of each pin of the integrated circuit to ground and compares it with typical reference values to evaluate the quality of the integrated circuit. In addition, there are a variety of resistance detection methods, including online resistance detection methods and off-line resistance detection methods. The voltage detection method is used to detect the voltage value of the integrated circuit pin and compare it with the appropriate reference value to determine whether there is a problem with the integrated circuit and the cause of the problem.
The reference data and detection data used in the voltage detection method are two different forms of data. The resistance detection method measures the forward and reverse DC resistance values of each pin of the integrated circuit to ground and compares it with typical reference values to evaluate the quality of the integrated circuit. In addition, there are a variety of resistance detection methods, including online resistance detection methods and off-line resistance detection methods.
(4) Total current measurement method. This method senses the total current flowing through the power supply line of the integrated circuit. This technology can be used to evaluate the quality of the integrated circuit. Since most integrated circuits under test are directly coupled, any damage to one of them (such as breakdown or open circuit of a specific PN junction) may cause the subsequent stage to saturate and shut down, thus changing the total current. Therefore, measuring the total current can be used to evaluate the quality of integrated circuits. You can also determine the total current by measuring the voltage drop across the resistor in the power path and using Ohm’s law.
(5) Ground AC and DC voltage measurement technology. This technology uses a multimeter to measure the DC voltage barrier when power is applied to determine the operating voltage and DC supply voltage of peripheral components. It measures the DC voltage between each IC pin and ground and compares it to the expected value. To narrow down the defect and determine how to measure the damaged part and compare it to normal values.
At present, the DC voltage method cannot be used to judge the AC signal emitted from the output end, and the AC voltage method must be used to judge. After setting to AC voltage detection, a multimeter should be set to the “AC position” to measure the AC voltage between this pin and the circuit “ground”. If the voltage is abnormal, you can disconnect the pin and check the voltage at the terminal to see if it is a problem with the integrated circuit or peripheral components.
Bucking involves numerically reducing the integrated circuit supply voltage. Typical operating voltages of integrated circuits are moderate, and if a substandard integrated circuit is used or if other factors cause the operating voltage of the integrated circuit to be too high and cause the integrated circuit to self-excite, the voltage reduction method can be used to correct the problem.
The diode method often includes the method of increasing the power supply voltage, the method of connecting resistors in series at the power supply end, the method of connecting diodes in series at the power supply end, etc. The method of increasing the power supply voltage is rarely used during maintenance. The reason is that whether it is using an external power supply or changing the introduction path of the integrated circuit power line, this method is time-consuming and laborious. However, whether it is a step-up method or a step-down method, the voltage must be maintained within the limit voltage.
According to the actual maintenance experience of integrated circuits, when testing the internal DC equivalent resistance of an integrated circuit in-circuit, there is no need to solder the integrated block from the circuit. It is only necessary to remove the pin with abnormal voltage or in-circuit resistance together with the ground pin from the circuit. removed. To determine if it’s good or bad, disconnect it from the board, leave the other pins in place, and measure the forward and reverse resistance values within R between the test pin and the ground pin.
Nonetheless, it should be noted that you should try to use safe, simple, easy, economical, reliable, fast methods and combinations of these methods. We must think carefully and analyze, use multiple methods flexibly, explore patterns, and discover problems in inspections promptly and accurately.