Several simple methods for testing the quality of IC chips

Date：2022-03-29 16:41:43Views：1712

IC chip, English name integrated circuit chip, is to put the integrated circuit formed by a large number of microelectronic components (transistors, resistors, capacitors, etc.) on a plastic base to make a chip. At present, the quality of IC chips plays a very important role in the whole electronic products. It directly affects the quality problems of the whole products after they go on the market. So for the staff, how to correctly detect the quality of IC chip? This paper briefly introduces several methods.

1. Offline detection

This method is carried out when the IC is not welded into the circuit. Generally, the forward and reverse resistance values of each pin corresponding to the grounding pin can be measured with a multimeter, and compared with the intact IC.

2. Online detection

① DC resistance detection is the same as offline detection

This is a method to detect the DC resistance of IC pins in the circuit (IC in the circuit), AC / DC voltage to ground and total working current through a multimeter..

② DC working voltage measurement

This is a method to measure the DC power supply voltage and the working voltage of peripheral components with the DC voltage gear of multimeter under the condition of power on; Detect the DC voltage value of each IC pin to the ground and compare it with the normal value, so as to compress the fault range and find out the damaged components.

Pay attention to the following eight points during measurement:

(1) The multimeter should have enough internal resistance, which should be at least 10 times greater than the resistance of the measured circuit, so as not to cause large measurement error.

(2) Usually turn each potentiometer to the middle position. If it is a TV, the signal source should adopt a standard color bar signal generator.

(3) Anti skid measures shall be taken for the probe or probe. IC is easily damaged due to any instantaneous short circuit. The following methods can be taken to prevent the probe from sliding: take a section of bicycle valve core and cover it on the probe tip, and grow the probe tip about 05mm, which can not only make the probe tip in good contact with the tested point, but also effectively prevent slipping, and there will be no short circuit even if it touches the adjacent point.

(4) When the measured voltage of a pin is inconsistent with the normal value, it should be analyzed according to whether the pin voltage has an important impact on the normal operation of the IC and the corresponding changes of other pin voltages, so as to judge the quality of the IC.

(5) IC pin voltage will be affected by peripheral components. In case of leakage, short circuit, open circuit or variable value of peripheral components, or a potentiometer with variable resistance is connected to the peripheral circuit, the position of the sliding arm of the potentiometer will change the pin voltage.

(6) The voltage of each IC pin is considered normal if it is normal; If the voltage of some IC pins is abnormal, start from the maximum deviation from the normal value and check whether the peripheral components are faulty. If there is no fault, the IC is likely to be damaged.

(7) For dynamic receiving devices, such as TV sets, the voltage of each pin of IC is different when there is no signal. If it is found that the pin voltage should not change, but changes greatly, but does not change with the signal size and different positions of adjustable components, it can be determined that the IC is damaged.

(8) For devices with multiple working modes, such as video recorders, the voltage of each IC pin is also different under different working modes.

3. AC working voltage test method

Use a universal meter with DB gear to measure the approximate value of AC voltage of IC. If there is no DB gear, a. 1 - 0.5 "isolated DC capacitor can be connected in series with the positive probe. This method is applicable to those with relatively low working frequency. However, it should be noted that these signals will be affected by the natural frequency and different waveforms. Therefore, the measured data are approximate and for reference only.

4. Total current measurement method

By measuring the total current of IC power supply, we can judge the quality of IC. Because most of the IC is DC coupling, when the IC is damaged (such as PN junction breakdown or open circuit), it will cause the back-up and cut-off of the later stage, and change the total current. Therefore, measuring the total current can judge the quality of IC. The current value can be calculated by measuring the voltage on the loop resistance.