What does the element that brings about invalidation of yuan of parts of an apparatus have?
source:LONTL CNC Machining
The invalidation of component accepts the impact of the element such as humidity, temperature, voltage, machinery continuously. 1, temperature brings about invalidation: Environmental temperature is the main factor temperature that brings about component invalidation the influence of parts of an apparatus of metabolic half-and-half conductor: Compose is extremely geminate model the knot of basic and unit P-N of semiconductor device is very sensitive to the change of temperature, when P-N the knot slants reversely when buy, carry by minority stream child the metabolic effect that formation retrorse leakage current suffers temperature, its relation is: In type: ICQ -- the ICQR of retrorse leakage current when ― temperature T0C -- the T of retrorse leakage current when temperature TR ℃ - TR -- the absolute value that temperature changes by on type can see, temperature every are elevatory 10 ℃ , ICQ will increase one times. This produces the working drop that causes transistor amplifier electric current of drift, transistor to magnify coefficient happening change, characteristic curve produces change, dynamic limits decrescent. Temperature and the concern that allow power comsumption are as follows: In type: PCM -- ― is the biggest allow power comsumption TjM -- ― is highest allow knot lukewarm T -- -- RT of use environment temperature -- ― thermal resistance by on type can see, of temperature elevatory will make of transistor the biggest allow power comsumption to drop. Written guarantee as a result of P-N to pressure fall the effect that suffers temperature is bigger, what form for main unit with P-N so is ambipolar model semiconductor logic component (the integrated circuit such as TTL, HTL) voltage transmission character and interference rejection are spent also have close relationship with temperature. When temperature is elevatory, p-N writtens guarantee to pressure fall reduce, its open the door and close n will be reduced, this makes what the tolerance of voltage of low n interference rejection of component follows temperature is elevatory and decrescent; Lift and increase what tolerance of voltage of tall n interference rejection follows temperature, cause output undee and n deflection, lack fidelity, stable state is maladjusted, even thermal breakdown. Temperature change changes to the influence temperature of resistor basically is temperature to the influence of resistor when lifting, the thermal noise of resistor increases, block value deviate is nominal value, allow the demote below dissipation probability. For instance, the carbolic film resistor of RXT series lifts in temperature when 100 ℃ , permission dissipation probability is only nominal the 20 ％ of the value. But this one character that we also can use resistor, for instance, have a kind of resistance that passes special design: PTC (temperature coefficient thermal resistor) with NTC (thermal resistor of negative temperature coefficient) , the effect that their block value suffers temperature is very big. To PTC, when its temperature lifts when some threshold value, its resistance can increase quickly. Use this one character, can use its in circuit board in shedding protective circuit too, because some kind of breakdown causes the electricity that carries it to increase,should arrive after electric current of its threshold value, the temperature of PTC lifts quickly, in the meantime, its resistance greatens, limitation carries its electricity, obtain the protection to circuit. And after trouble removal, the electricity that carries it is reduced, the temperature of PTC returns to normal, in the meantime, its resistance also restores to be worth normally to its. To NTC, its characteristic is his what resistance follows temperature is elevatory and reduce. Temperature change changes those who cause capacitance to dielectric loss to the influence temperature of capacitance, affect its service life thereby. Temperature every are elevatory when 10 ℃ , the life of capacitor reduces 50 ％ , still cause block to allow time constant to change at the same time, because dielectric loss passes,happen even big and the circumstance of thermal breakdown. In addition, temperature is elevatory also will make inductance coil, transformer, choke the insulation property that wait drops. 2, humidity brings about invalidation: Humidity is exorbitant, fall when the dirt that contains soda acid sex on circuit board when, the solder dot that corrodes yuan of parts of an apparatus and wiring place, cause solder dot to fall off, contact ruptures. Humidity is exorbitant also be the main reason that causes coupling of leakage of electricity. And humidity is too low arise easily again electrostatic, so environmental humidity should be controlled in reasonable level. 3, exorbitant voltage brings about invalidation of parts of an apparatus: Bring to bear on be in yuan of voltage stability on parts of an apparatus it is the fundamental condition that assures yuan of parts of an apparatus to work normally. Exorbitant voltage can increase the hot loss of yuan of parts of an apparatus, cause electric breakdown even. To capacitor, 5 power of direct ratio of its failure rate at capacitance voltage. To integrated circuit, exceed its the biggest the direct damage that the voltage that allows voltage value will cause parts of an apparatus. Voltage puncture is to show electronic parts has can highest compression is worth susceptive, exceed this to allow a value, parts of an apparatus is put in invalidation risk. The expressional form of active component and passive component invalidation has a difference a bit, but also voltage allows upper limit. Transistor component has compression value, exceed compression value to be able to have loss to component, exceed diode, capacitance to wait for instance, voltage exceeds the compression value of component to be able to cause their breakdown, if energy very congress causes thermal breakdown, component can discard as useless. 4, influence of oscillatory, concussion: Mechanical vibration and concussion can make component of a few in-house defective quickens invalidation, cause disastrous trouble, mechanical vibration still can make solder dot, line ball dot happens become loose, bring about a contact undesirable; If vibration brings about lead not to answer some touching even, what can produce a few image to be less than is sequential. The breakdown mode that causes possibly, reach invalidation analysis: Electric cross stress (Electrical Over Stress, EOS) it is a kind of common harm the means of electronic parts, it is the attaint cause with yuan of common parts of an apparatus, its behave way is to pass to press or cross abortion to give birth to much heat energy, make temperature of yuan of interior of parts of an apparatus exorbitant damage thereby yuan of parts of an apparatus (what big the daily life of a family says is burned-out) , it is a kind of when bring about by the pulse in electrical system common harm the means of electronic parts. CNC MillingCNC Machining