At present, most NTC thermistors on the market are made from ceramic processes based on metal oxides such as manganese, cobalt, nickel, copper, etc.. Now, NTC thermistors are widely used in temperature measurement, temperature control, temperature compensation, environmental detection and so on. In recent years, our NTC manufacturers in varieties and production scale of NTC thermistor have made new progress. Isostatic pressure technology, thick film technology, etc., in production, application of NTC component has been improved and popularized. The change range of NTC thermistor at room temperature is 10Ω to 1000000Ω, temperature coefficient is -2% to -6.5%. However, in the existing production methods, the temperature control accuracy generally reaches 0.3℃ to 1.5℃, although some products can control the temperature accuracy within 0.2℃, but only limited to a single point or a narrow temperature range. In order to overcome the shortcomings of existing technology, let’s introduce a medical high-precision NTC thermistor which is high precision, wide measurement range, and it can achieve multi-point measurement accuracy of up to 0.2℃ of the production.
This producing method of medical high-precision NTC thermistors includes the following steps:
1) Powder preparation: on the basis of the target B value, prepare powder in proportion, the main components of powder are CoO, NiO, MnO, CuO, ZnO, MgO, FeO, CrO, ZrO, TiO, etc..
2) Ball milling: put the prepared powder into the rolling tank and add the Zirconium balls, and add a certain ratio of solvents in twice. Solvents mainly include: ethanol, toluene, dispersant, CK24, plasticizer. The main purpose of ball milling is to make the powder mix evenly and grind into nano powder;
3) Thin strip isostatic pressing: the ball-milled slurry is made into thin strip by Tape Casting Method, the thickness of thin strip is 70μm ± 2μm; Then the formed thin strips are peeled, laminated, sliced and finally pressed into embryo ceramics with hot water;
4) Raw spindle sintering: the pressured raw spindle ceramics are kept for 2~3 hours in a high temperature sintering furnace, which is slowly increased to 1120~1350℃ at the rate of 1℃/min; And then slowly reduced to 100℃ at the rate of 1℃/min; After that, cooling down naturally.
5) Ceramic chip silver printing: the prepared silver paste is printed on the two ends of the NTC ceramicn chip with the silver printing equipment, electrode layers are formed at both ends of the NTC ceramic chips; Get NTC silver chips;
6) Silver chips firing: the silver-printed NTC silver chips sintered through the silver-firing furnace, so that the silver layers and the ceramic chips fully bonded to form a fixed structure;
7) Dicing: according to the target resistance value, the silver-fired NTC silver chips diced precisely with the slicing machine, then can get the cuboid or square NTC chips; The measuring accuracy of each point can be controlled within ±0.2℃ within the range of 0~70℃ to ensure the accuracy of each temperature measuring point;
8) Welding: the wire and NTC chip can welded into a second-wire resistance or three-wire resistance according to the characteristics of the product;
9) Encapsulation: second-wire resistance and third-wire resistance can be encapsulated with environmental protection adhesive;
10) Curing: the coating adhesive is fixed and formed by high-temperature constant-temperature oven curing;
11) Test sorting: sorting with the thermistor tester, and finally get the medical high-precision NTC thermistor.
Medical high-precision NTC thermistor, which can be widely used in the temperature measurement, temperature control of medical industry. Its consistency, repeatability, stability is excellent, the measurement range can be in the range of 0~70℃, the accuracy of each point can be controlled within the range of ±2℃, to ensure the accuracy of each temperature point. At the same time, this thermistor not only has small size, fast response, long service life and other advantages, but also has high resistance value, the slope of temperature characteristics curve, etc.. Using medical high-precision NTC thermistor can be more accurately and effectively to play the effect of temperature measurement, temperature control, make electronic devices more stable, temperature measured more accurately to reduce test errors.