CN1244936C - Manufacture of nano level MOS thermistor - Google Patents

Abstract

The present invention relates to a manufacture method of nano stage metal oxide semiconductor thermosensitive resistors. The present invention takes acetates or nitrates of manganese, nickel and iron as raw materials, and a nano stage power material is firstly prepared by a chemical liquid phase coprecipitation method. The powder is secondly decomposed, presintered, formed, isostatic pressed and sintered in high temperature, the powder is subsequently sliced for blackening electrodes and is scribed into thermosensitive resistance chips, and finally, the powder is welded with lead wires and are packaged, wherein dispersing agent is added in the process of preparing the nano stage powder material by the chemical liquid phase coprecipitation method so as to prevent the powder agglomerating in manufacture and drying processes. The method has the characteristics of good technical repeatability, good product consistency, stable performance, etc., and electrical properties of the product can reach a level of similar Japanese products and can completely replace import.

Description

The manufacture method of nanosize metal oxide semiconductor thermistor

Technical field

The present invention relates to a kind of manufacture method that is used for the nanosize metal oxide semiconductor thermistor of temperature survey, temperature control and/or temperature-compensating etc.

Background technology

Thermistor is the ceramic semiconductors that ohmmeter reveals corresponding great variety along with variations in temperature, its most important characteristic is the very accurate resistance with high temperature coefficient of resistance and relative temperature characteristic, in operating temperature range, this sensitive property to variations in temperature causes the resistance value of resistance to produce huge variation.Because sensitivity, accuracy and the stability of thermistor, thermistor all is a kind of transducer that has superiority most in many application usually, and these application comprise temperature survey, temperature control and temperature-compensating etc.The application of thermistor is very extensive, comprises commercial consumption electronic product, automobile, medical electronics application, food processing and processing, communication, military affairs and Aero-Space or the like.Some practical applications of thermistor comprise the household electrical appliance such as level gauging, shooting, thermometer, ductus venosus, blood analysis, automatic climate control, myocardium needle probe, air-conditioning and coffee pot and the data logger etc. of air, soil, fluid temperature detector for example.

The metal-oxide semiconductor (MOS) thermistor of single-ended epoxy packages has good stability, and characteristics such as reliability height are applicable to the temperature survey and the control of domestic air conditioner.The thermistor of the existing similar structures of Japan, parameter comes out, and China's this kind thermistor relies on import substantially.Even if but intact this identical thermistor of structural behaviour, because its manufacturing process difference, Main Ingredients and Appearance and ratio thereof are all variant.Japan mainly adopts oxide mixing and ball milling method or slaine melting heat decomposition method to prepare powder body material in recent years, and its electrical parameter is B _25/85=3435, R ₂₅=9.5～10.5K Ω.Domestic preparation belongs to oxide thermosensitive resistor material and generally adopts oxide mixing and ball milling method.

Summary of the invention

Technical problem to be solved by this invention is the manufacture method that the more excellent nanosize metal oxide semiconductor thermistor of a kind of main component and manufacturing process difference and performance is provided at the prior art present situation.

The present invention is through for many years exploration, the acetate of research employing manganese, nickel, iron or nitrate are as raw material, prepare nanometer grade powder material with chemical coprecipitation, its technology and material composition and prior art have marked difference, and the electrical parameter of all products all reaches the standard of external like product.

The present invention solves the problems of the technologies described above the technical scheme that is adopted: the manufacture method of this nanosize metal oxide semiconductor thermistor, it is to be raw material with the acetate of manganese, nickel, iron or nitrate, adopt the chemical liquid phase coprecipitation to prepare nanometer grade powder material earlier, then powder is decomposed, pre-burning, carry out again moulding, etc. static pressure and high temperature sintering, cut into slices, the blackening electrode, be diced into thermistor chip, carry out wire bonds and encapsulation at last thereafter; Wherein, dispersant is arranged adopting the chemical liquid phase coprecipitation to prepare to add in the nanometer grade powder material process, making, reuniting in the dry run to prevent powder; Each set of dispense of above-mentioned raw material is than being (molar percentage):

Manganese 30～35 nickel 30～40 iron 30～35

It is pure to analyze (AR) level manganese 30～35 that above-mentioned chemical liquid phase coprecipitation prepares nanometer grade powder material, nickel 30～40, the acetate of iron 30～35 (molar percentage) or nitrate are raw material, with water is the manganese that solvent is made 0.8～1.2M, nickel, the salting liquid of iron is as precipitated liquid, the dispersant that adds 4～6% (weight ratios) in the precipitated liquid, under vigorous stirring, evenly add precipitation reagent in the precipitated liquid, treat that adding distilled water repeatedly after precipitation is finished cleans, simultaneously solution being carried out sonicated reunites to prevent sediment, the last cleaning adopts absolute ethyl alcohol to dewater, and then sediment dried, decompose, pre-burning.

Described dispersant is that molecular weight is 500～800 polyethylene glycol.

Described precipitation reagent is the sal volatile of 0.8～1.2M, by volume, and the addition of precipitation reagent is 1.2-1.5 a times of precipitated liquid.

Described decomposition temperature is 450 ± 10 ℃, and the time is 12～15 hours; Calcined temperature is 850 ℃ ± 10 ℃, and the time is 6 ± 1 hours; Powder be molded over the column of finishing on the hydraulic press and being shaped to Ф 60 ± 2mm; Deng static pressure in isostatic pressing machine, finish and described column outside be surrounded by freshness protection package, pressure is 300-350Mpa; The high temperature sintering temperature is 1250 ± 5 ℃, and sintering time is 2.5～3.5 hours; The blackening electrode temperature is 850 ± 5 ℃, and electrode is that Pd content is the Ag-Pd electrode of 10% (wt%); Wire bonds adopts wicking welding, the lead frame that goes between and make for Ф 0.3 ± 0.1mm tinned wird; Be coated with one deck silicones after having welded, be coated with epoxy resin at last and make single-ended epoxy packages thermistor finished product.

The distinctive feature of the manufacture method of nanosize metal oxide semiconductor thermistor of the present invention:

When (1) adopting the chemical coprecipitation preparation of nano powder, because precipitation reagent adopts ammonium carbonate, thermistor prepares the manganese in the raw material, and nickel, three kinds of elements of iron all form complex compound than easy and NH4+, and pH value has great influence to end product composition ratio; Because course of reaction PH excursion is very big, difficult control; Too high then some element of pH value complexing in a large number during reaction end, pH value is low excessively, some element precipitates again not exclusively, and these all can cause the elementary composition ratio of end product and the greatest differences of initial formula, and this has just caused the characteristics of process repeatability difference in the production process.Ratio, the reaction time of the then strict control precipitation reagent of the present invention, thus reached the purpose of controlling the element ratio of powder body material.

(2) adopt chemical coprecipitation to prepare powder, because the sediment powder granule is nano level powder, surface activity is big, very easily reunites, become in the course of reaction simultaneously precipitation the further addition polymerization of zwitterion this reunion.Add the surface activity that polyethylene glycol has reduced powder granule among the present invention, and adopt the reunion of the way destruction powder of ultrasonic cleaning, simultaneously, adopt ethanol dehydration further to reduce the reunion of powder.Shown in accompanying drawing 1 powder electromicroscopic photograph, the powder granule of making has like this reached nanoscale, and it is active high, and size is consistent, and the elementary composition ratio is even.

(3) the present invention adopts isostatic pressing process to guarantee that powder sintering becomes the density of ceramic sintered bodies, adopts semi-conductive processing technology such as scribing, and section has guaranteed consistency of product.The processing technology of production technology conjunction with semiconductors of pottery makes the rate of finished products of thermistor, and long-time stability have had and increase substantially.

Description of drawings

Fig. 1 is the electromicroscopic photograph of nanosize metal oxide semiconductor powder.

Embodiment

Below in conjunction with accompanying drawing the present invention is described in further detail.

Embodiment one

With the pure manganese acetate of commercially available analysis, nickel acetate, ferric nitrate is raw material, press manganese acetate 33mol%, nickel acetate 33mol%, the ratio of ferric nitrate 34mol% takes by weighing 2 moles of above-mentioned raw materials, add distilled water and make the precipitated liquid of 1M, the precipitation reagent that uses 2.4 moles of commercially available ammonium carbonates to make concentration as 1M; And in precipitated liquid, add the poly-ethanol (molecular weight 500～800) of 5% (wt%), and the rate of addition of precipitation reagent with 50ml/ minute added in the precipitated liquid under vigorous stirring, add the back and continue to stir 30 minutes, precipitation is finished.

After will having sedimentary solution left standstill, the supernatant that inclines adds distilled water in the sediment, places 600W supersonic wave cleaning machine stirring and washing, leaves standstill hypsokinesis and removes supernatant; Filter after cleaning five times repeatedly, in sediment, add the 1500ml absolute ethyl alcohol at last, put in the supersonic wave cleaning machine and clean, filter drying then.

The powder of oven dry promptly got nanometer metal oxide powder in 6 hours 850 ± 10 ℃ of pre-burnings then 450 ± 10 ℃ of thermal decompositions 12 hours, and so far powder preparing is finished.As shown in Figure 1, the particle in the powder has reached nanoscale.

Powder is molded into the cylinder that diameter is Ф 60mm ± 2mm on hydraulic press, waits static pressure after wrapping with freshness protection package, pressure is 330Mpa, dwell time is 10 minutes, rise to 1250 ± 5 ℃ at warming and cooling rate then with 1 ℃/minute, and at this sintering temperature 3 hours, Low fire ceramic block.

With slicing machine ceramic cylinder is cut into slices, section back coated on both sides Ag-Pd (Pd content 10%) electrode was handled 15 minutes at 850 ± 5 ℃, press the required size scribing then, thermistor chip, the present embodiment chips is of a size of: V=a * a * d, 1.5≤a≤2.0mm 0.3≤d≤0.4mm.Is chip gripper wicking welding in the tinned conductor of 0.3mm at the diameter of forming, coats one deck with silicones then, coats with epoxy resin and is the thermistor finished product.

Record the resistance value R of its 25 ℃ and 85 ℃ ₂₅, R ₈₅, calculate temperature-sensitive constant B value.

$B_{25/50}=\frac{\ln R_{25}\left(\mathrm{\Ω}\right)-\ln R_{85}\left(\mathrm{\Ω}\right)}{1/298.15\left(K\right)-1/358.15\left(K\right)}$

Gained thermistor electrical parameter is: B _25/85=3435 * (1 ± 1%), R ₂₅=9.5-10.5K Ω.

The thermistor long-time stability are in resistance-time rate of change: 25 ℃ of resistance R are surveyed in beginning earlier ₂₅A is put in 100 ℃ of environment and was surveyed 25 ℃ of resistance value (R in 1000 hours again ₂₅B), try to achieve resistance change rate (%) by following formula:

Gained the results are shown in Table 1.The resistance change rate of the thermistor that the data declaration present embodiment makes in the table is lower than 1%, is better than Japanese like product.

Embodiment two

With the pure manganese acetate of commercially available analysis, nickel acetate, ferric nitrate is raw material, press manganese acetate 30mol%, nickel acetate 35mol%, the ratio of ferric nitrate 35mol% takes by weighing 2 moles of above-mentioned raw materials, add distilled water and make the precipitated liquid of 1.2M, the precipitation reagent that uses 2.4 moles of commercially available ammonium carbonates to make concentration as 1.2M; And in precipitated liquid, add the poly-ethanol (molecular weight 500～800) of 6% (wt%), and the rate of addition of precipitation reagent with 50ml/ minute added in the precipitated liquid under vigorous stirring, add the back and continue to stir 30 minutes, precipitation is finished.

After will having sedimentary solution left standstill, the supernatant that inclines adds distilled water in the sediment, places 600W supersonic wave cleaning machine stirring and washing, leaves standstill hypsokinesis and removes supernatant; Filter after cleaning five times repeatedly, in sediment, add the 1500ml absolute ethyl alcohol at last, put in the supersonic wave cleaning machine and clean, filter drying then.

The powder of oven dry promptly got nanometer metal oxide powder in 7 hours 850 ± 10 ℃ of pre-burnings then 450 ± 10 ℃ of thermal decompositions 15 hours, and so far powder preparing is finished.

Powder is molded into the cylinder that diameter is Ф 60mm ± 2mm on hydraulic press, wait static pressure after wrapping with freshness protection package, pressure is 350Mpa, dwell time is 12 minutes, rise to 1250 ± 5 ℃ at warming and cooling rate then with 1 ℃/minute, and at this sintering temperature 3.5 hours, Low fire ceramic block.

With slicing machine ceramic cylinder is cut into slices, section back coated on both sides Ag-Pd (Pd content 10%) electrode was handled 15 minutes at 850 ± 5 ℃, press the required size scribing then, thermistor chip, the present embodiment chips is of a size of: V=a * a * d, 1.5≤a≤2.0mm 0.3≤d≤0.4mm.Is chip gripper wicking welding in the tinned conductor of 0.3mm at the diameter of forming, coats one deck with silicones then, coats with epoxy resin and is the thermistor finished product.

Record the resistance value R of its 25 ℃ and 85 ℃ ₂₅, R ₈₅, calculate temperature-sensitive constant B value.

$B_{25/50}=\frac{\ln R_{25}\left(\mathrm{\Ω}\right)-\ln R_{85}\left(\mathrm{\Ω}\right)}{1/298.15\left(K\right)-1/358.15\left(K\right)}$

Gained thermistor electrical parameter is: B _25/85=3435 * (1 ± 1%), R ₂₅=9.5-10.5K Ω.The thermistor long-time stability are in resistance-time rate of change: 25 ℃ of resistance R are surveyed in beginning earlier ₂₅A is put in 100 ℃ of environment and was surveyed 25 ℃ of resistance value (R in 1000 hours again ₂₅B), try to achieve resistance change rate (%) by following formula:

Gained the results are shown in Table 1.The resistance change rate of the thermistor that the data declaration present embodiment makes in the table is lower than 1%, is better than Japanese like product.

Embodiment three

With the pure manganese acetate of commercially available analysis, nickel acetate, ferric nitrate is raw material, press manganese acetate 30mol%, nickel acetate 40mol%, the ratio of ferric nitrate 30mol% takes by weighing 2 moles of above-mentioned raw materials, add distilled water and make the precipitated liquid of 0.8M, the precipitation reagent that uses 2.4 moles of commercially available ammonium carbonates to make concentration as 0.8M; And in precipitated liquid, add the poly-ethanol (molecular weight 500～800) of 5% (wt%), and the rate of addition of precipitation reagent with 50ml/ minute added in the precipitated liquid under vigorous stirring, add the back and continue to stir 30 minutes, precipitation is finished.

After will having sedimentary solution left standstill, the supernatant that inclines adds distilled water in the sediment, places 600W supersonic wave cleaning machine stirring and washing, leaves standstill hypsokinesis and removes supernatant; Filter after cleaning five times repeatedly, in sediment, add the 1500ml absolute ethyl alcohol at last, put in the supersonic wave cleaning machine and clean, filter drying then.

The powder of oven dry promptly got nanometer metal oxide powder in 5 hours 850 ± 10 ℃ of pre-burnings then 450 ± 10 ℃ of thermal decompositions 13 hours, and so far powder preparing is finished.

Powder is molded into the cylinder that diameter is Ф 60mm ± 2mm on hydraulic press, waits static pressure after wrapping with freshness protection package, pressure is 330Mpa, dwell time is 11 minutes, rise to 1250 ± 5 ℃ at warming and cooling rate then with 1 ℃/minute, and at this sintering temperature 3 hours, Low fire ceramic block.

With slicing machine ceramic cylinder is cut into slices, section back coated on both sides Ag-Pd (Pd content 10%) electrode was handled 15 minutes at 850 ± 5 ℃, press the required size scribing then, thermistor chip, the present embodiment chips is of a size of: V=a * a * d, 1.5≤a≤2.0mm 0.3≤d≤0.4mm.Is chip gripper wicking welding in the tinned conductor of 0.3mm at the diameter of forming, coats one deck with silicones then, coats with epoxy resin and is the thermistor finished product.

Record the resistance value R of its 25 ℃ and 85 ℃ ₂₅, R ₈₅, calculate temperature-sensitive constant B value.

$B_{25/50}=\frac{\ln R_{25}\left(\mathrm{\Ω}\right)-\ln R_{85}\left(\mathrm{\Ω}\right)}{1/298.15\left(K\right)-1/358.15\left(K\right)}$

Gained thermistor electrical parameter is: B _25/85=3435 * (1 ± 1%), R ₂₅=9.5-10.5K Ω.The thermistor long-time stability are in resistance-time rate of change: 25 ℃ of resistance R are surveyed in beginning earlier ₂₅A is put in 100 ℃ of environment and was surveyed 25 ℃ of resistance value (R in 1000 hours again ₂₅B), try to achieve resistance change rate (%) by following formula:

Gained the results are shown in Table 1.The resistance change rate of the thermistor that the data declaration present embodiment makes in the table is lower than 1%, is better than Japanese like product.

Embodiment four

With the pure manganese acetate of commercially available analysis, nickel acetate, ferric nitrate is raw material, press manganese acetate 33mol%, nickel acetate 37mol%, the ratio of ferric nitrate 30mol% takes by weighing 2 moles of above-mentioned raw materials, add distilled water and make the precipitated liquid of 1M, the precipitation reagent that uses 2.4 moles of commercially available ammonium carbonates to make concentration as 1.2M; And in precipitated liquid, add the poly-ethanol (molecular weight 500～800) of 4% (wt%), and the rate of addition of precipitation reagent with 50ml/ minute added in the precipitated liquid under vigorous stirring, add the back and continue to stir 30 minutes, precipitation is finished.

After will having sedimentary solution left standstill, the supernatant that inclines adds distilled water in the sediment, places 600W supersonic wave cleaning machine stirring and washing, leaves standstill hypsokinesis and removes supernatant; Filter after cleaning five times repeatedly, in sediment, add the 1500ml absolute ethyl alcohol at last, put in the supersonic wave cleaning machine and clean, filter drying then.

The powder of oven dry promptly got nanometer metal oxide powder in 6 hours 850 ± 10 ℃ of pre-burnings then 450 ± 10 ℃ of thermal decompositions 10 hours, and so far powder preparing is finished.

Powder is molded into the cylinder that diameter is Ф 60mm ± 2mm on hydraulic press, waits static pressure after wrapping with freshness protection package, pressure is 330Mpa, dwell time is 11 minutes, rise to 1250 ± 5 ℃ at warming and cooling rate then with 1 ℃/minute, and at this sintering temperature 3 hours, Low fire ceramic block.

With slicing machine ceramic cylinder is cut into slices, section back coated on both sides Ag-Pd (Pd content 10%) electrode was handled 15 minutes at 850 ± 5 ℃, press the required size scribing then, thermistor chip, the present embodiment chips is of a size of: V=a * a * d, 1.5≤a≤2.0mm 0.3≤d≤0.4mm.Is chip gripper wicking welding in the tinned conductor of 0.3mm at the diameter of forming, coats one deck with silicones then, coats with epoxy resin and is the thermistor finished product.

Record the resistance value R of its 25 ℃ and 85 ℃ ₂₅, R ₈₅, calculate temperature-sensitive constant B value.

$B_{25/50}=\frac{\ln R_{25}\left(\mathrm{\Ω}\right)-\ln R_{85}\left(\mathrm{\Ω}\right)}{1/298.15\left(K\right)-1/358.15\left(K\right)}$

Gained thermistor electrical parameter is: B _25/85=3435 * (1 ± 1%), R ₂₅=9.5-10.5K Ω.The thermistor long-time stability are in resistance-time rate of change: 25 ℃ of resistance R are surveyed in beginning earlier ₂₅A is put in 100 ℃ of environment and was surveyed 25 ℃ of resistance value (R in 1000 hours again ₂₅B), try to achieve resistance change rate (%) by following formula:

Gained the results are shown in Table 1.The resistance change rate of the thermistor that the data declaration present embodiment makes in the table is lower than 1%, is better than Japanese like product.

The relevant parameter of table 1, each embodiment gained thermistor:

Embodiment	Composition ratio of components (mol%)			B 25/85Value	Resistance R 25(KΩ)	Resistance change rate (%)
							Manganese acetate	Nickel acetate	Ferric nitrate
	One	33	33							34	3435	9.5～10.5	0.54
Two				30	35	35	3435	9.5～10.5	0.32
	Three	30	40							30	3435	9.5～10.5	0.67
Four				33	37	30	3435	9.5～10.5	0.42
	Japan's imported with original packaging product									3435	9.5～10.5	1.76

Claims (5)

1, a kind of manufacture method of nanosize metal oxide semiconductor thermistor, it is characterized in that: it is to be raw material with the acetate of manganese, nickel, iron or nitrate, adopt the chemical liquid phase coprecipitation to prepare nanometer grade powder material earlier, then powder is decomposed, pre-burning, carry out again moulding, etc. static pressure and high temperature sintering, cut into slices, the blackening electrode, be diced into thermistor chip, carry out wire bonds and encapsulation at last thereafter; Wherein, dispersant is arranged adopting the chemical liquid phase coprecipitation to prepare to add in the nanometer grade powder material process, making, reuniting in the dry run to prevent powder; The molar percentage of above-mentioned each component of raw material is:

Manganese 30～35 nickel 30～40 iron 30～35.

2, the manufacture method of nanosize metal oxide semiconductor thermistor as claimed in claim 1, it is characterized in that: it is to analyze pure level manganese that the chemical liquid phase coprecipitation prepares nanometer grade powder material, nickel, the acetate of iron or nitrate are by mole percentage manganese 30～35, nickel 30～40, iron 30～35 is raw material, with water is the manganese that solvent is made 0.8～1.2M, nickel, the salting liquid of iron is as precipitated liquid, the dispersant that adds 4～6wt% in the precipitated liquid, under vigorous stirring, evenly add precipitation reagent in the precipitated liquid, treat that adding distilled water repeatedly after precipitation is finished cleans, simultaneously solution being carried out sonicated reunites to prevent sediment, the last cleaning adopts absolute ethyl alcohol to dewater, and then sediment dried, decompose, pre-burning.

3, the manufacture method of nanosize metal oxide semiconductor thermistor as claimed in claim 1 or 2 is characterized in that: described dispersant is that molecular weight is 500～800 polyethylene glycol.

4, the manufacture method of nanosize metal oxide semiconductor thermistor as claimed in claim 2 is characterized in that: described precipitation reagent is the sal volatile of 0.8～1.2M, by volume, and the addition of precipitation reagent is 1.2-1.5 a times of precipitated liquid.

5, the manufacture method of nanosize metal oxide semiconductor thermistor as claimed in claim 1 or 2 is characterized in that: decomposition temperature is 450 ± 10 ℃, and the time is 12～15 hours; Calcined temperature is 850 ℃ ± 10 ℃, and the time is 6 ± 1 hours; Powder be molded over the column of finishing on the hydraulic press and being shaped to Φ 60 ± 2mm; Deng static pressure in isostatic pressing machine, finish and described column outside be surrounded by freshness protection package, pressure is 300-350Mpa; The high temperature sintering temperature is 1250 ± 5 ℃, and sintering time is 2.5～3.5 hours; The blackening electrode temperature is 850 ± 5 ℃, and electrode is that Pd content is the Ag-Pd electrode of 10wt%; Wire bonds adopts wicking welding, the lead frame that goes between and make for Φ 0.3 ± 0.1mm tinned wird; Be coated with one deck silicones after having welded, be coated with epoxy resin at last and make single-ended epoxy packages thermistor.