Semiconductor component failure characteristics analysis

First, the characteristics of resistance damage

Resistance is the largest number of components in electrical equipment,semiconductor testing but not the highest damage rate components. Resistor damage to the most common open-circuit, resistance value is less common, resistance value becomes small very rare. Commonly, there are carbon film resistors, metal film resistors, wirewound resistors and insurance resistors. The first two types of resistors are the most widely used, and their damage is characterized by: first, low resistance (below 100Ω) and high resistance (more than 100kΩ) of the damage rate is higher, the intermediate resistance (such as hundreds of ohms to dozens of kilo-ohms) of the damage is rare; second, low resistance resistance damage is often burnt black, it is easy to find, and high resistance resistance damage is seldom traces. Wirewound resistors are generally used as high-current current limiters with small resistance values. Cylindrical wirewound resistors when burned some will be blackened or the surface burst skin, cracks, some have no trace. Cement resistors are a kind of wirewound resistors, which may break when burned out, otherwise there is no visible trace. Some will blow off a piece of skin on the surface when the fuse resistor burns out, and some have no traces, but they will never be burnt and blackened. According to the above characteristics, when checking the resistance can be focused on, quickly find the damaged resistor.

Second, the characteristics of electrolytic capacitor damage

Electrolytic capacitors in electrical equipment in a large amount, the failure rate is very high.semiconductor failure analysis Electrolytic capacitor damage has the following manifestations: first, complete loss of capacity or capacity to become smaller; second, slight or serious leakage; third, loss of capacity or capacity to become smaller with leakage. Find the damaged electrolytic capacitor methods are:

(1) look: some capacitors will leak when damaged, the surface of the circuit board below the capacitor and even the appearance of the capacitor will have a layer of oil stains, this capacitor can never be used again; some capacitors will bulge after damage, this capacitor can not be continued to use;

(2) Touch: some electrolytic capacitors with serious leakage will be hot after power on, and will even be hot when touched by fingers, this kind of capacitor must be replaced;

(3) electrolytic capacitors have electrolyte inside, a long time baking will make the electrolyte dry,aotomatic prober resulting in reduced capacitance, so focus on checking the heat sink and high-power components near the capacitor, the closer it is, the greater the possibility of damage.

Third, diodes, transistors and other semiconductor device damage characteristics

Diode, triode damage is generally PN junction breakdown or open circuit, which is mostly short-circuit breakdown. In addition, there are two kinds of damage performance: one is the thermal stability deterioration, manifested as normal when the power on, work for a period of time, the occurrence of soft breakdown; the other is the PN junction characteristics of the deterioration of the PN junction, with the multimeter R × 1k measurements, the PN junction is normal, but on the machine after the work can not be normal, if you use the R × 10 or R × 1 low range gear measurement, it will be found that the PN junction forward resistance is larger than the normal value. Measurement of diodes and triodes can be measured with a pointer multimeter in the road, the more accurate method