CN101425352B - Technical process for enhancing stability of NTC heat variable resistor - Google Patents
Technical process for enhancing stability of NTC heat variable resistor Download PDFInfo
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- CN101425352B CN101425352B CN2008102343087A CN200810234308A CN101425352B CN 101425352 B CN101425352 B CN 101425352B CN 2008102343087 A CN2008102343087 A CN 2008102343087A CN 200810234308 A CN200810234308 A CN 200810234308A CN 101425352 B CN101425352 B CN 101425352B
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Abstract
The invention relates to a technique method for improving the stability of an NTC thermal resistor chip and belongs to the technical field of the manufacture technique of electronic devices. The technique method comprises the steps of mixing ingredients, ball milling, prepressing forming after drying, isostatic pressing, first sintering, slicing and second sintering. The NTC thermistor ceramic chip is sintered twice in two different process stages to eliminate internal non-equilibrium defects of the NTC thermistor ceramic chip caused by the stress action due to high temperature and machine tooling, and to speed up the stabilization process; meanwhile, a layer of compact sintered molten layer is formed on the surface of ceramic sheets to effectively eliminate the open pores. Thus the invention can significantly improve the stability of the NTC thermal resistor chip to solve the problems that the NTC thermal resistor chip has low stability and bad reliability.
Description
Technical field
The present invention relates to a kind of sintering process for making of ceramic electron element chip, especially a kind of process that improves NTC themistor chip stability belongs to electronic device manufacture craft technical field.
Background technology
At present, the complete manufacturing process steps of NTC themistor routine is as follows:
1, batching: various common metal oxide powders (being mainly cupric oxide, manganese oxide, nickel oxide, iron oxide, aluminium oxide, cobalt oxide) are evenly mixed in required ratio.
2, ball milling: the powder for preparing is added water and abrasive media put into ball mill and carry out ball milling, make powder form the fineness of submicron particles.
3, oven dry pre-molding:, in mould, be pressed into the shape of setting in advance with forcing press with the oven dry of the powder behind the ball milling.
4, static pressure compacting such as: will wrap up the pre-molding ingot of getting well and be put into etc. in the static pressure cavity and finalize the design.
5, high temperature sintering: the moulding ingot that suppresses put into carry out sintering in the high temp, vertical sintering furnace, make its potteryization.---800 ℃ (1 ℃/min of heating rate is incubated 120 minutes)---1100-1300 ℃ (0.5 ℃/min of heating rate is incubated 180 minutes)---room temperature (natural cooling) that sintering process is controlled to be: room temperature.
6, cutting: with cutting mechanics the ceramic core sheet stock piece that sinters is cut, cut into the thermistor chip eggshell china sheet that sets thickness.
Carry out electrode preparation afterwards again: on resistance eggshell china sheet surface, the casket body that the resistance chip will be housed after the oven dry is put into and is carried out sintering in the kiln with the even scrubbing brush of mode of lead-free silver slurry by the silk screen bat printing; Scribing: the eggshell china sheet is cut into square chip particle (as size 0.25mm * 0.5 with scribing machine
2Mm etc.); Encapsulation: adopt different packaged types to encapsulate on the chip particle that makes, can be made into the NTC themistor of different purposes, outward appearance, model, specification.
Along with NTC themistor in various IEDs, use extensively, the stability of the thermistor that plays the effect of observing and controlling temperature is had higher requirement.Facts have proved that above-mentioned original process can't satisfy the needs that the high stability NTC themistor is provided.
Retrieval is found, application number is that 200610147824.7 Chinese patent application discloses a kind of NTC thermistor manufacture method, a kind of NTC thermistor of this method, this method is the ceramic green sheet matrix with the multilayer green compact, portion is formed with internal electrode within it, make matrix and internal electrode form fine and close the combination, internal electrode electrode base-material comprises one or more the composition in silver, lead, platinum, the bronze end, and base-material contains mass ratio and is not more than 20% nickel by powder.Its manufacture method is 1. preparation ceramic green sheet matrixes; 2. on the ceramic green sheet matrix, apply internal electrode; 3. the ceramic green sheet matrix of deposition coating or uncoated internal electrode forms the multilayer green compact arbitrarily; 4. the multilayer green compact are fired under the highest sintering temperature 1000-1400 ℃; 5. at the outside termination electrode that forms of fired body.The problem that this method exists is that fine and close nickeliferous spinel layer is to be difficult to control between the interior electrode that forms by sintering and the ceramic matrix, the both thickness of uncontrollable this nickeliferous spinelle, also uncontrollable nickeliferous concentration gradient, because microchip itself is small-sized, guarantee the consistency of product electrical property, it is very accurate that the thickness of above-mentioned spinelle and concentration gradient must be controlled, but adopt this kind allow method that nickel spread naturally in sintering process be impossible the assurance properties of product stablizing with consistent.And this method promptly allows to improve the long-time stability of NTC product, but can not guarantee consistency of product, and the qualification rate of NTC product can decline to a great extent on the contrary.Therefore, a great problem that existing NTC themistor chip stability is low, poor reliability becomes the high-quality NTC themistor of manufacturing.
Summary of the invention
The technical problem to be solved in the present invention is: at the low difficult problem of the NTC themistor ceramic chip of above-mentioned making stability, propose a kind ofly can significantly improve the sintering process for making that NTC themistor ceramic chip stability does not reduce product percent of pass again.
In order to solve above technical problem, the applicant has proposed the process of following raising NTC themistor ceramic chip stability through comparative experiments repeatedly:
The first step, batching: the common metal oxide powder is evenly mixed in required ratio;
Second step, ball milling: mixed powder is added water and abrasive media carries out ball milling, make powder form submicron particles;
The 3rd step, oven dry pre-molding:, in mould, be pressed into the moulding ingot of setting shape in advance with the oven dry of the powder behind the ball milling;
The 4th step, etc. static pressure compacting: the moulding ingot is put into etc. is shaped into thermistor chip material piece in the static pressure cavity;
The 5th step, first sintering: thermistor chip material piece is heated to 1100 ℃～1300 ℃ by room temperature, is incubated 5-8 hours, make the back cooling of the preliminary potteryization of thermistor chip material piece;
The 6th step, section: tentatively the thermistor chip material piece of potteryization cuts into the thermistor chip eggshell china sheet of setting thickness;
The 7th step, sintering for the second time: thermistor chip eggshell china sheet is heated to 1100 ℃～1300 ℃ by room temperature, be incubated 5-8 hours, its the highest sintering temperature preferably is controlled at than low 40-80 ℃ of first sintering temperature, through sintering for the second time the NTC themistor chip into.
Carry out electrode preparation, scribing, encapsulation afterwards again, make high-quality NTC themistor.The mechanism of action of above double sintering is as follows:
(1) ceramic body in manufacturing process after waiting static pressure compacting and high temperature sintering solid density reached more than 97%, but inside still exists little apparent pore through form open shape micropore behind the machine cuts flakiness on the surface, the outer environmental change of resistive element can arrive ceramic body inside by these micropores, and the result certainly will influence the stability of ceramic interior molecules performance.Double sintering can make ceramic surface form the sintered molten layer of one deck densification, has effectively eliminated open micropore.
(2) in NTC thermistor chip manufacture process, because of high temperature and mach stress, can form nonequilibrium defect in the ceramic body, the result is owing to particle migration in the ceramic chip does not catch up with rate temperature change, make easily that component is uneven distribution in the ceramic chip, cause unstable properties.The applicant is by furtheing investigate and experiment discovery repeatedly the sintering curre of chip resistance and time variation, take the double sintering method can quicken stabilization procedures, make the microstructure of ceramic chip produce more equally distributed variation tendency, thereby guarantee the high stability of NTC themistor.
In brief,, eliminated its inner nonequilibrium defect that Yin Gaowen and mach stress caused in the NTC thermistor chip manufacture process, quickened stabilization procedures by to the double sintering of NTC thermistor ceramic chip two different process stages; Make the ceramic sheet surface form the sintered molten layer of one deck densification simultaneously, effectively eliminated open pore; Therefore can significantly improve the stability of NTC themistor, solve that NTC themistor chip stability is low, the difficult problem of poor reliability, compared with prior art, have significant substantive distinguishing features and outstanding progress.
Description of drawings
The present invention is further illustrated below in conjunction with accompanying drawing.
Fig. 1 is the temperature changing curve diagram of one embodiment of the invention first sintering.
Fig. 2 is the one embodiment of the invention temperature changing curve diagram of sintering for the second time.
Embodiment
Embodiment one
The process concrete steps that this preferred embodiment improves NTC themistor chip stability are as follows:
1, batching: metal oxide powder manganese oxide, nickel oxide, iron oxide, aluminium oxide, cobalt oxide are evenly mixed according to the weight ratio of following optimization:
Mn
3O
4: NiO: Fe
2O
3: Co
3O
4: Al
2O
3=56.48: 14.48: 19.04: 6.65: 3.35 (conventional compound percentages is: CuO: Mn
3O
4: NiO: Fe
2O
3: Al
2O
3: Co
3O
4=0～2.5%: 30～70%: 10～25%: 15～30%: 0.5～4.5%: 20～50%).
2, ball milling: mixed uniformly powder is added water and abrasive media put into ball mill and carry out ball milling, make powder form the fineness of submicron particles.Metal oxide powder: water: abrasive media (zirconia ball)=1: 1: 4 (weight ratio).
3, oven dry pre-molding:, in mould, be pressed into the moulding ingot of setting shape in advance with forcing press with the oven dry of the powder behind the ball milling.
4, static pressure compacting such as: will wrap up the pre-molding ingot of getting well and be put into etc. in the static pressure cavity, isostatic pressing machine pressure rises to 2500kg/cm
2, and pressurize 5 minutes.
5, first sintering: the moulding ingot that suppresses put into carry out sintering in the high temp, vertical sintering furnace, make its preliminary potteryization.Sintering process is controlled to be: room temperature---950 ℃ of (1 ± 0.5 ℃/min of heating rate, be incubated 120 minutes)---1180 ℃ (0.5 ± 0.1 ℃/min of heating rate is incubated 360 minutes)---1000 ℃ (0.25 ± 0.05 ℃ of rate of temperature fall/min)---800 ℃ (0.35 ± 0.05 ℃ of rate of temperature fall/min)---200 ℃ (1.5 ± 0.5 ℃ of rate of temperature fall/min)---room temperature (natural cooling).The highest sintering temperature that adopts for the different materials proportioning preferably gets final product for 20～60 ℃ than the sintering temperature reduction of routine.
6, cutting: with cutting mechanics the ceramic core sheet stock piece that sinters is cut, cut into the thermistor chip eggshell china sheet that sets thickness.
7, NTC thermistor chip eggshell china sheet is put into carried out double sintering in the high temp, vertical sintering furnace, the control of sintering process temperature is basic identical with first sintering, just the highest sintering temperature needs to make required NTC themistor chip than low 40-80 ℃ of first sintering temperature.
Afterwards, carrying out electrode preparation: on resistance eggshell china sheet surface, the casket body that the resistance chip will be housed after the oven dry is put into and is carried out sintering in the kiln with the even scrubbing brush of mode of lead-free silver slurry by the silk screen bat printing; Scribing: the eggshell china sheet is cut into square chip particle (as size 0.25mm * 0.5 with scribing machine
2Mm etc.); Encapsulation: the chip particle after making adopts different packaged types to encapsulate, and promptly can be made into the NTC themistor of high-quality different purposes, outward appearance, model, specification.
Experimental results show that, adopt above process to solve the difficult problem that mechanical mixture dosing method NTC themistor chip stability is low, aging coefficient is bigger than normal, significantly improve the stability and the reliability of NTC themistor chip, thereby improved the quality of thermistor greatly.
In addition to the implementation, the present invention can also have other execution modes.All employings are equal to the technical scheme of replacement or equivalent transformation formation, all drop on the protection range of requirement of the present invention.
Claims (5)
1. process that improves NTC themistor chip stability may further comprise the steps:
The first step, batching: with common metal oxide powder CuO, Mn
3O
4, NiO, Fe
2O
3, Al
2O
3, Co
3O
4Evenly mix in following required ratio
CuO∶Mn
3O
4∶NiO∶Fe
2O
3∶Al
2O
3∶Co
3O
4＝0～2.5％∶30～70％∶10～25％∶15～30％∶0.5～4.5％∶20～50％
Second step, ball milling: mixed powder is added water and abrasive media carries out ball milling, make powder form submicron particles;
The 3rd step, oven dry pre-molding:, in mould, be pressed into the moulding ingot of setting shape in advance with the oven dry of the powder behind the ball milling;
The 4th step, etc. static pressure compacting: the moulding ingot is put into etc. is shaped into thermistor chip material piece in the static pressure cavity;
The 5th step, first sintering: thermistor chip material piece is heated to 1100 ℃～1300 ℃ by room temperature, is incubated 5-8 hour, make the back cooling of the preliminary potteryization of thermistor chip material piece;
The 6th step, section: tentatively the thermistor chip material piece of potteryization cuts into the thermistor chip eggshell china sheet of setting thickness;
The 7th step, sintering for the second time: thermistor chip eggshell china sheet is heated to 1100 ℃～1300 ℃ by room temperature, is incubated 5-8 hour, sinter the NTC themistor ceramic chip into.
2. according to the process of the described raising NTC themistor of claim 1 chip stability, described first sintering rises to 950 ℃ by room temperature with the heating rate of 1 ± 0.5 ℃/min, is incubated 120 minutes; Heating rate with 0.5 ± 0.1 ℃/min rises to 1180 ℃ again, is incubated 360 minutes; Cooling is cooled to room temperature gradually.
3. according to the process of the described raising NTC themistor of claim 2 chip stability, it is characterized in that: described second time, sintering rose to 950 ℃ by room temperature with the heating rate of 1 ± 0.5 ℃/min, was incubated 120 minutes; Heating rate with 0.5 ± 0.1 ℃/min rises to 1120 ℃ again, is incubated 360 minutes; Cooling is cooled to room temperature gradually.
4. according to the process of the described raising NTC themistor of claim 3 chip stability, it is characterized in that: the described cooling gradually reduced to 1000 ℃ with the rate of temperature fall of 0.25 ± 0.05 ℃/min by maximum temperature, reduce to 800 ℃ with the rate of temperature fall of 0.35 ± 0.05 ℃/min again, reduce to 200 ℃ with the rate of temperature fall of 1.5 ± 0.5 ℃/min again, last natural cooling is as for room temperature.
5. according to the process of the described raising NTC themistor of claim 3 chip stability, it is characterized in that: metal oxide powder in the described ball milling step: water: the weight ratio of abrasive media is 1: 1: 4.
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| CN101425352B true CN101425352B (en) | 2010-12-01 |
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Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102627446B (en) * | 2012-04-26 | 2013-09-04 | 恒新基电子（青岛）有限公司 | Method for preparing negative temperature coefficient (NTC) thermistor and NTC thermistor chip manufactured by same |
| CN102775139B (en) * | 2012-08-20 | 2014-11-12 | 肇庆爱晟电子科技有限公司 | Manufacturing method of NTC (Negative Temperature Coefficient) thermo-sensitive semiconductor ceramic body material |
| CN103030406A (en) * | 2013-01-02 | 2013-04-10 | 桂林理工大学 | Ptc ceramic sintering method |
| CN103073278B (en) * | 2013-01-30 | 2014-10-08 | 广州新莱福磁电有限公司 | Manufacturing method of high-precision and high-reliability NTC thermistor chip |
| CN105665644B (en) * | 2014-11-18 | 2018-05-08 | 中国科学院金属研究所 | A kind of hot sizing technique of ceramic core |
| CN106348733B (en) * | 2016-08-25 | 2020-09-08 | 南京时恒电子科技有限公司 | High-precision NTC material and manufacturing method thereof |
| CN106384635B (en) * | 2016-08-26 | 2018-10-02 | 中国振华集团云科电子有限公司 | A kind of chip NTCR and preparation method thereof |
| CN108147790B (en) * | 2017-12-26 | 2021-04-30 | 珠海爱晟医疗科技有限公司 | Medical gold-containing high-precision high-stability NTC (negative temperature coefficient) thermosensitive chip and manufacturing method thereof |
| CN108546089A (en) * | 2018-03-30 | 2018-09-18 | 四川西汉电子科技有限责任公司 | A kind of preparation process of NTC themistor |
| CN109133901A (en) * | 2018-10-29 | 2019-01-04 | 惠州嘉科实业有限公司 | Thermistor containing iron series and preparation method thereof |
| CN114464384B (en) * | 2022-03-02 | 2022-10-14 | 深圳安培龙科技股份有限公司 | Gold electrode NTC thermistor chip, preparation method and temperature sensor |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101157550A (en) * | 2007-09-12 | 2008-04-09 | 山东中厦电子科技有限公司 | Low resistance/high B-value negative temperature coefficient thermo-sensitive material and method for preparing same |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101157550A (en) * | 2007-09-12 | 2008-04-09 | 山东中厦电子科技有限公司 | Low resistance/high B-value negative temperature coefficient thermo-sensitive material and method for preparing same |
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Address after: 211121, Nanjing Road, Jiangning District, Jiangsu 18, Jinyang Road Patentee after: Nanjing Shiheng Electronics Co., Ltd. Address before: 211101 Shuanglong road 179-1, Jiangning District, Jiangsu, Nanjing Patentee before: Nanjing Shiheng Electronics Co., Ltd. |
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Granted publication date: 20101201 Termination date: 20181111 |
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