PTC thermistor
PTC (Positive Temperature Coefficient) is the acronym means that the temperature coefficient is, the great pan-corrected temperature coefficient of semiconductor materials or components. Usually we talk about the PTC is correct temperature coefficient thermistor, or PTC thermistor. PTC thermistor temperature is a typical sensitivity of the semiconductor resistor, over a certain temperature (Curie temperature), its resistance values with increasing temperature of a step higher.
PTC thermistor organizational structure and functions of principle
Ceramic materials are usually good for high-insulation resistance, and ceramic PTC thermistor is barium titanate-based, the other doped polycrystalline ceramic materials manufacturer, has a lower resistance and semiconducting properties. The purpose of doping through a chemical prices higher material as crystal lattice yuan to achieve: in the crystal lattice of Barium Titanate ion ion or were part by the higher price of ion substitution, it has become a considerable quantity a free electronic conductivity. The PTC thermistor effect, that is, the higher resistance values Step reasons, the material organization is composed of many small-ceramic components, in the grain interface, the so-called grain boundaries (boundary) create potential barrier, impeding cross-border electronic access to the adjacent regions, and therefore have a high resistance, which in effect was offset by lower temperatures: in the grain boundary on the high dielectric constant and spontaneous polarization strength at low temperatures, hampered Barrier and the formation of the free flow of electronic. And this effect at high temperature, the dielectric constant intensity and polarization substantially reduced, leading to the barrier and resistance increased significantly, showing a strong PTC effect.
PTC thermistor manufacturing process
Performance will be able to achieve electrical and thermal performance requirements of the mixture (barium carbonate and titanium dioxide, and other materials) weighing, mixing wet grinding again, dehydration dried stem made of wafer-pressure molding, rectangular, circular, cellular - like rough. These suppress good rough at the higher temperature (1400 ° C or so) into ceramic sintering, and then to electrodes on the surface of the metal, according to the resistance values of the stalls. According to the finished product structure brazing Packaging shell or assembly, after the final comprehensive testing.
weighing>> milling>> pre-sintered>> granulation
molding>> sintering>> fix the electrode>> resistance separation
brazing>> packaging assembly>> printing >> pressure detection
resistance of test>> final testing>> packaging>> depositing
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