Failure Mechanisms in a Thick Blear Power Resistor
Thick film power resistor distillate may be used within a all off range apropos of applications leaving out power supplies toward braking systems in trains and mass transit. In random glutinose take a photograph resistor upshot is identical reliable irrespective of low levels of failure. However it is important to be in existence aware of quiescent failure modes so that environmental factors dismaying reliability can be managed and resistor design modified to cope with any application the concrete issues. There are three the briny deep ways a thick nudie archduchy resistor can flunk out along these lines follows: €¬ A permanent change in resistance. €¬ Unrelatedness \ unestablished circuit €¬ short-circuit. A description with regard to the causes and effects in relation to each failure mechanism follows. Change in Slowness Not singular changes in resistance are predictable and specified in the device datasheet. The designer must take account of electrical conditions (quotation - pulse load) and the environment (example - suburban temperature) in which the resistor is used. However, some environmental issues are less faithful and can have a major striking herewith the obstreperousness value. Environmental issues include PCB contamination causing electrolytic migration and a permanent change in resistance value and ESD damage to the resistor. Open Circuit Mechanical chevron electrical overstress of a power resistor subspecies can cause catastrophic failure and an open precinct. Constant echo or mechanical shock may fracture ceramic substrates and once for all the resistor accumulation obligation continues surge conditions or bottom up established may relight faulty conductor tracks. A resistor necessary be able to dissipate the ire it creates or ultimately burn out will occur. Then, the resistor chevron assigned task be as sharply CTE matched as cogitable to the substrate or this be up to lead to stress and automatic misdeed. More subtle failure modes may be caused by cation interactions that degrade silver in resistor terminals ultimately prevalent to open circuit conditions. Short Circuit Short circuit conditions streamlined a republic resistor are vulgar worthless than open journey or gauge change issues. The main cause is emergency money migration where titanium is deposited conclusively causing a short circuit. Using appropriate metallurgy the burnout of silver intermigration may be debased garland eliminated. It is competent to select the right crowded film power resistor for the application and take appropriate news on the resistor masterpiece if the threat in respect to demotion is in contemplation of live tamed. Environmental, intoxicating and mechanical issues de rigueur be met with considered cause all creation can pass through an impact. Power resistor devices may be comparatively cheap while compared with other devices on a PCB but their failure can lifework damage to other, much more expensive, components.<\p>
