6 Causes Of Thick Movie Resistor Failure
Thick movie resistor failure is rarely caused by a failure of the resistive component but is commonly thanks to exterior environmental aspects this sort of as mechanical and electrical stresses and handling challenges. Failures can be possibly classed as a degradation of general performance or complete failure (generally as an open instead than a quick circuit).
Six prevalent leads to of thick film resistor failure are:
Thermal difficulties
Mechanical pressure
Continuous overload
Surge
Environmental – metal migration
ESD
MECHANICAL FAILURES
Apart from handling hurt top to substrate cracks and chips most mechanical problems is induced by possibly vibration or inappropriate mounting of the system. Micro cracking of the resistor product brought on by vibration or compression / extension of the resistor owing to inappropriate mounting can direct to improve in the resistance value, problems to the resistive ingredient or part failure. In all cases the danger of failure is increased by presence of a single or much more of the stresses listed underneath.
ENVIRONMENTAL Factors
Even though a thick movie resistor is typically coated to defend it from dampness and intense chemical features environmental components this kind of as humidity and contamination nonetheless have to have thorough thing to consider. Both equally can cause steel migration concerning the terminals of the resistor foremost to possible limited circuit or a modify in resistance benefit.
THERMAL Challenges
Most mechanical failure modes of thick movie resistors are propagated by heat. It is as a result crucial to realize the warmth dissipation qualities of the resistor and substrate substance. A minimal energy resistor dissipates heat by using conduction as a result of its part prospects or connections, when a large electric power resistor dissipates warmth by radiation.
When recent passes through a resistor it generates warmth and the differential thermal expansions of the unique product used in the resistor production course of action induces stresses in the resistor. Temperature Coefficient of Resistance (TCR) is the best recognised parameter utilised to specify a thick film resistor balance, and defines the resistive element’s sensitivity to temperature change. Power Coefficient of Resistance (PCR) quantifies the resistance modify owing to self-heating when energy is used and is notably vital for resistors applied in power apps.
OVERLOAD Conditions
A steady in excess of-load of a resistor product degrades the insulation resistance and adjustments the resistor parameters around time. Voltage worry can bring about conduction from usually non-conductive materials in the resistor movie primary to deterioration and sometimes failure due to warm spots. It is for that reason essential to observe the resistor optimum specified voltage.
SURGE Ailments
The key element in identifying the surge survivability of a thick film resistor is the mass of a resistor aspect, which is right proportional to its thickness multiplied by its area area. The geometry of a resistor also has an effect on its surge endure ability. A more substantial area spot success in a bigger movie mass, and finally an enhanced surge general performance. The enhanced surface area region enables far more heat dissipation which is critical in electricity resistor apps.
The remaining issue contributing component to a resistor surge capability is how the component is resistor trimmed to set up the ultimate resistance benefit. The process made use of for trimming can build weak spots that induce failure beneath surge ailments.
ESD
Destruction by means of ESD is a latent defect that can be complicated to detect. The resistor may well be partially degraded by ESD but go on to perform its meant perform. On the other hand, the prospects of untimely or catastrophic failure of the resistor gadget are increased, especially if the gadget is exposed to a single or more of the stresses stated earlier mentioned.
Conclusion
A resistor may be the most affordable expense component in a method but failure can be just as catastrophic as failure of any other system factor. It is for that reason essential to fully grasp possible failure modes and how they could be resolved. A partnership with a expert company with extensive term working experience of thick film resistor technological know-how and its manufacture can minimise the threats of failure.
