Method for manufacturing high-precision NTC thermistor chip

A technology for a thermistor chip and a manufacturing method, applied to resistors with negative temperature coefficients, resistors, non-adjustable metal resistors, etc., can solve the problem of low pass rate of resistance value, inability to obtain resistivity, B value and The pass rate of finished products, harsh sintering process and other issues can be achieved to improve the pass rate of chip resistance and B value, easy to control the production process, and control the particle size of the powder

Active Publication Date: 2017-05-24
GUANGZHOU MAGNET ELECTRICITY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, when the Ni content in the NTC thermistor formula system is relatively high, a more stringent sintering process is required, which results in a resistivity ρ of 2 to 25kΩ·cm, B 25/85 NTC thermistor chips with a temperature of 3200 ~ 3600K are difficult to obtain
[0003] At present, there are mainly the following methods for producing NTC thermistor chips that meet the above requirements: 1) Ingots are made by combining dry pressing and cold isostatic pressing. , to obtain the NTC thermistor chip, this method limits the addition of Ni element, the pass rate of 1% product resistance value of the chip is low, in order to ensure that the pass rate of 1% product resistance value after scribing can reach more than 80%, the Ni element Generally, the addition amount shall not exceed 10at%. When the addition amount of Ni element is relatively large, due to the significant difference in the composition and microstructure of the outer layer and the core of the ceramic, it is easy to cause the resistivity to change in the radial or longitudinal directio

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] 1) Weigh 433.99g of trimanganese tetraoxide, 444.05g of nickel oxide, 583.58g of ferric oxide and 38.39g of alumina, mix ball mill for 20h, calcine at 450°C for 2h, ball mill for 20h, and calcinate at 950°C for 2h to obtain thermal ceramic powder;

[0045] 2) Ball mill the heat-sensitive ceramic powder for 20 hours, add 22.50g of binder PVA, granulate, and pass through a 60-mesh sieve to obtain a shaped powder;

[0046] 3) Add the molding powder to the hydraulic press, hold the pressure at 50MPa for 1min, and obtain a preform of 45mm×45mm×17mm, put the preform into a cold isostatic press, press at 300MPa for 2min, and obtain a molding block;

[0047] 4) Put the molded compact into the sintering furnace, control the oxygen intake to 0.5L / min, raise the temperature to 1200°C at a heating rate of 10°C / min, keep it for 2 hours, and cool down to 500°C at a cooling rate of 2°C / min , cooled naturally to room temperature to obtain a ceramic sintered block;

[0048] 5) Use a s...

Embodiment 2

[0054] 1) Weigh 396.10g of trimanganese tetraoxide, 156.48g of nickel oxide, 509.30g of ferric oxide and 489.31g of cobalt oxide, mix ball mill for 20h, calcinate at 550°C for 2h, ball mill for 20h, and calcinate at 1050°C for 2h to obtain heat sensitive ceramic powder;

[0055] 2) Mill the heat-sensitive ceramic powder for 20 hours, add 27.92g of binder PVA, granulate, and pass through a 60-mesh sieve to obtain a shaped powder;

[0056] 3) Add the molding powder to the hydraulic press, hold the pressure at 60MPa for 1min, and obtain a preform of 45mm×45mm×17mm, put the preform into a cold isostatic press, press at 300MPa for 3min, and obtain a molding block;

[0057] 4) Put the formed compact into the sintering furnace, control the oxygen flow rate to 1.0L / min, raise the temperature to 1250°C at a heating rate of 15°C / min, keep it for 1.5h, and cool it down to 400°C at a cooling rate of 5°C / min °C, naturally cooled to room temperature to obtain a ceramic sintered block;

[...

Embodiment 3

[0064] 1) Weigh 398.22g of trimanganese tetroxide, 448.19g of nickel oxide, 589.02g of ferric oxide and 64.57g of alumina, mix ball mill for 20h, calcinate at 650℃ for 2h, ball mill for 20h, and calcinate at 850℃ for 2h to obtain thermal ceramic powder;

[0065] 2) Ball mill the heat-sensitive ceramic powder for 20 hours, add 18.00g of binder PVA, granulate, and pass through a 60-mesh sieve to obtain a shaped powder;

[0066] 3) Add the molding powder to the hydraulic press, hold the pressure at 40MPa for 5min, and obtain a preform of 45mm×45mm×17mm, put the preform into a cold isostatic press, press at 400MPa for 2min, and obtain a molding block;

[0067] 4) Put the molded block into the sintering furnace, control the oxygen intake to 0.5L / min, raise the temperature to 1100°C at a heating rate of 5°C / min, keep it for 3 hours, and cool down to 600°C at a cooling rate of 3°C / min , cooled naturally to room temperature to obtain a ceramic sintered block;

[0068] 5) Use a slice...

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PUM

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Abstract

The invention discloses a method for manufacturing a high-precision NTC thermistor chip. The method comprises a step 1) of weighing corresponding metal oxides according to a chemical formula Mn3-x-y-zNixFeyCozQtO4, performing mixing ball-milling, low-temperature calcination, ball-milling crushing and high-temperature calcination, and obtaining thermal sensitive ceramic powder; a step 2) of performing ball-milling on the thermal sensitive ceramic powder, adding an organic binder, and performing drying, pelleting and sieving to obtain formed powder; a step 3) of performing dry pressing and isostatic pressing on the formed powder, and obtaining formed briquette; a step 4) of adding the formed briquette into an atmosphere furnace, performing sintering in the weak oxidizing atmosphere, and obtaining agglomerate; a step 5) of cutting the agglomerate into slices, coating the slices with silver or gold electrodes, performing heat treatment, cutting the slices into required sizes, and obtaining the high-precision NTC thermistor chip. The decomposition of FeMnNiO4 is restrained by controlling oxygen partial pressure in the sintering process, ingredient segregation is reduced by introducing low-temperature calcination before presintering, the production process is controlled easily, the chip resistance and B value pass rate are high, and the reliability is high.

Description

technical field [0001] The invention relates to a manufacturing method of a high-precision NTC thermistor chip. Background technique [0002] Negative temperature coefficient (NTC) thermistors refer to electronic ceramic materials whose resistance decreases with increasing temperature, and are widely used in temperature sensors to measure temperature. In recent years, with the rapid development of science and technology, people have higher and higher requirements for the temperature measurement accuracy and temperature control accuracy of NTC thermistor chips. Nickel element has the characteristics of reducing material resistivity and B value at the same time, and it is not easy to cause NTC thermistor aging like Cu element, so it can be conveniently added to the NTC thermistor formula as the main component to adjust the NTC thermal resistance. The resistivity and material constant B value of the varistor. However, due to the variable valence state of Ni, NiO will be decom...

Claims

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Application Information

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IPC IPC(8): C04B35/26C04B35/626C04B35/64H01C7/04
CPCC04B35/2666C04B35/62605C04B35/64C04B2235/3217C04B2235/3263C04B2235/6562C04B2235/6565C04B2235/6567C04B2235/6583H01C7/043
Inventor 汪小明谭育新陈军王学钊杨安学陈贵立
Owner GUANGZHOU MAGNET ELECTRICITY
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