What are the phenomena of component damage? IC electronic damage characteristics and detection methods

Date：2022-04-18 15:13:50Views：1122

The components damaged by overvoltage can not see obvious specific changes from the surface, but the parameters have changed. When it is more serious, the circuit board around the components turns yellow and black. Devices are the most easily damaged items, but their faults are regular. General faults are divided into two types: electrical parameter damage and physical damage. Then the damage of electrical parameters includes the damage caused by voltage and current exceeding the rated value. Physical damage includes fracture, deformation, resistance parameter change and other manifestations. What are the phenomena of component damage? The life of electronic components is not only related to its own structure and properties, but also closely related to its service environment and its role in the circuit.

Characteristics of resistance damage

Resistance is the largest number of components in electrical equipment, but it is not the component with the highest damage rate. Open circuit is the most common resistance damage. It is rare for the resistance to become larger, and it is very rare for the resistance to become smaller. Common are carbon film resistance, metal film resistance, wire wound resistance and safety resistance.

The first two kinds of resistors are most widely used, and their damage characteristics are as follows: first, the damage rate of low resistance value (below 100 Ω) and high resistance value (above 100k Ω) is high, and the damage of intermediate resistance value (such as hundreds of Ω to tens of thousands of Ω) is very little; Second, when the low resistance resistance is damaged, it is often burnt and blackened, which is easy to find, while there are few traces when the high resistance is damaged.

Wire wound resistance is generally used for high current current limiting, and the resistance value is small. When the cylindrical wire wound resistance is burnt out, some will be blackened or the surface will burst and crack, and some will have no trace. Cement resistance is a kind of wire wound resistance, which may break when burned out, otherwise there is no visible trace. When the fuse resistor is burnt out, some surfaces will blow off a piece of skin, and some have no trace, but they will never be burnt and blackened. According to the above characteristics, we can focus on checking the resistance and quickly find out the damaged resistance.

Characteristics of electrolytic capacitor damage

Electrolytic capacitors are widely used in electrical equipment and have a high failure rate. The electrolytic capacitor is damaged in the following ways:

First, the capacity is completely lost or reduced;

Second, slight or serious leakage;

Third, loss of capacity or reduction of capacity with leakage.

The methods to find the damaged electrolytic capacitor are as follows:

(1) Look: some capacitors will leak liquid when they are damaged. There will be a layer of oil stains on the surface of the circuit board under the capacitor and even on the surface of the capacitor. This kind of capacitor can never be used again; Some capacitors will bulge after being damaged, and this kind of capacitor can not continue to be used;

(2) Touch: after starting up, some electrolytic capacitors with serious leakage will heat up and even burn your hands when touching with your fingers. This kind of capacitor must be replaced;

(3) There is electrolyte inside the electrolytic capacitor. Baking for a long time will dry the electrolyte and reduce the capacitance. Therefore, it is necessary to focus on checking the capacitance near the heat sink and high-power components. The closer it is to it, the greater the possibility of damage.

Damage characteristics of semiconductor devices such as diodes and triodes

The damage of triode is generally PN junction breakdown or open circuit, in which breakdown and short circuit are most common.

In addition, there are two damage manifestations:

First, the thermal stability becomes worse, which shows that it is normal when starting up and soft breakdown occurs after working for a period of time;

The other is the deterioration of the characteristics of PN junction. Use multimeter R × 1K test, all PN junctions are normal, but they can't work normally after being on the machine. If R is used × 10 or R × 1. When measuring at low range, it will be found that the forward resistance of PN junction is greater than the normal value.

Measuring diodes and triodes can be measured on the road with a pointer multimeter. The more accurate method is:

Set the multimeter to R × 10 or R × Gear 1 (generally R) × Gear 10, and then use r when it is not obvious × 1) measure the forward and reverse resistance of PN junction of diode and triode on the road. If the forward resistance is not too large (relative to normal value), and the reverse resistance is large enough (relative to positive value), it indicates that the PN junction is normal. Otherwise, it is doubtful, and it needs to be measured after welding. This is because the peripheral resistance of diodes and triodes in general circuits is mostly more than hundreds or thousands of ohms. When measured in the circuit with the low resistance gear of multimeter, the influence of peripheral resistance on PN junction resistance can be basically ignored.

Characteristics of IC damage

The internal structure of integrated circuit is complex and has many functions. Any part damaged can not work normally. There are also two types of damage to integrated circuits: complete damage and poor thermal stability. When it is completely damaged, it can be removed and compared with the normal integrated circuit of the same model to measure the forward and reverse resistance of each pin to the ground. One or more pins can always be found with abnormal resistance value.

For those with poor thermal stability, the suspected integrated circuit can be cooled with absolute alcohol when the equipment is working. If the fault occurs later or no fault occurs again, it can be determined. Usually, it can only be eliminated by replacing a new integrated circuit.

The above is the relevant content of "performance of component damage" brought by the core creation test. I hope it can be helpful to you. We will bring more wonderful content in the later stage. The company's testing services cover: electronic component testing and verification, IC authenticity identification, product design and material selection, failure analysis, function testing, factory incoming material inspection, tape braiding and other testing items. Welcome to call Chuangxin testing. We will serve you wholeheartedly.