JP2007299940A

JP2007299940A - Positive thermistor and its manufacturing method

Info

Publication number: JP2007299940A
Application number: JP2006126824A
Authority: JP
Inventors: Toshiya Kitagawa; 俊也北川
Original assignee: Nichicon Corp
Current assignee: Nichicon Corp
Priority date: 2006-04-28
Filing date: 2006-04-28
Publication date: 2007-11-15

Abstract

<P>PROBLEM TO BE SOLVED: To provide a positive thermistor and the manufacturing method of the same capable of raising an allowable rush voltage upon impressing voltage, even in a case when the positive thermistor is miniaturized and reduced in the resistance thereof. <P>SOLUTION: The positive thermistor is manufactured by a method wherein titanic acid barium series porcelain composition is pulverized and mixed, then, dehydration, drying and calcination are effected to obtain calcined powder, then, the calcined powder is pulverized to granulate, and thereafter the granulated powder is formed to calcine the formed bod to obtain the positive thermistor. In this case, 50% particle diameter of particle size distribution accumulation of the formed granulation powder is 130-150 μm while particle size distribution width (difference between 90% particle diameter of accumulation of particle size distribution and 10% particle diameter of accumulation) is 90-120 μm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

この発明は、チタン酸バリウムを主成分とする正特性サーミスタおよびその製造方法に関するものである。 The present invention relates to a positive temperature coefficient thermistor mainly composed of barium titanate and a method for producing the same.

正の抵抗温度特性を有するチタン酸バリウムを主成分とする正特性サーミスタは、一般の粉末冶金法により、炭酸バリウム、酸化チタンを主原料とした原料粉末を混合し、仮焼して原料を得、造粒・成形し、焼成して得られた磁器に、さらに電極を形成して得られる（例えば特許文献１〜４参照）。 A positive temperature coefficient thermistor with barium titanate as the main component that has positive resistance temperature characteristics is obtained by mixing raw powders containing barium carbonate and titanium oxide as main raw materials and calcining them using a general powder metallurgy method. It is obtained by further forming an electrode on a porcelain obtained by granulation, molding and firing (see, for example, Patent Documents 1 to 4).

正特性サーミスタは、相転移温度（キュリー温度）付近で抵抗値が急激に増加する、正の抵抗温度特性を有し、冷蔵庫・エアコン等のモータ起動用、ブラウン管テレビの消磁用、その他の用途に幅広く用いられている。 The positive temperature coefficient thermistor has a positive resistance temperature characteristic in which the resistance value increases abruptly near the phase transition temperature (Curie temperature), for starting motors in refrigerators and air conditioners, for demagnetizing CRT televisions, and other applications. Widely used.

これらの用途において、特に近年、小形化や低抵抗化の要求が顕著である。また、突入許容電圧（素子に瞬時に電圧を印加したとき、素子が破壊せずに耐える最大電圧）の向上も求められている。 In these applications, particularly in recent years, the demand for downsizing and low resistance is remarkable. There is also a need to improve the inrush allowable voltage (the maximum voltage that the element can withstand without being destroyed when a voltage is instantaneously applied to the element).

しかしながら、上記の正特性サーミスタ素子の製造方法では、造粒粉の造粒径の均一化ができず、電圧印加時の発熱を均一に分散させることができなかったため、素子の内部と外部の熱量分布が偏ってしまい、構造上の歪みを生じることから突入許容電圧の向上を図ることができなかった。
特開平６−６４９２４号公報特開平２−２８９４２６号公報特開２００４−２１０６３６号公報特開平９−３３０８０４号公報 However, in the above method for producing a positive temperature coefficient thermistor element, the granulated powder cannot be made uniform in particle size, and heat generated during voltage application cannot be uniformly dispersed. Since the distribution is biased and structural distortion occurs, the inrush allowable voltage cannot be improved.
JP-A-6-64924 JP-A-2-289426 Japanese Patent Laid-Open No. 2004-210636 JP-A-9-330804

上記したように、正特性サーミスタに要求される条件は、従来と同じ使用環境、使用電圧に対する小形化や低抵抗化である。しかしながら、正特性サーミスタは同じ使用環境、使用電圧に対して小形化、低抵抗化すると、突入許容電圧も低下する傾向にある。 As described above, the conditions required for the positive temperature coefficient thermistor are the same usage environment and conventional voltage as in the conventional case, and miniaturization and low resistance. However, if the positive temperature coefficient thermistor is reduced in size and resistance for the same operating environment and operating voltage, the inrush allowable voltage tends to decrease.

しかし、小形化、低抵抗化した場合であっても、より高い突入許容電圧が求められるのが現状である。このような場合、従来から材料組成の検討が行われてきたが、材料組成面からは十分な特性が得られていなかった。 However, even if the size and resistance are reduced, a higher inrush allowable voltage is currently required. In such a case, the material composition has been studied conventionally, but sufficient characteristics have not been obtained in terms of the material composition.

本発明は、上記課題を解決するもので、粒度分布の累積５０％粒子径（中央値）と粒子径分布幅（粒度分布の累積９０％粒子径と、粒度分布の累積１０％粒子径との差）を調整することにより、突入許容電圧を向上させようとするものである。 The present invention solves the above-mentioned problems. The cumulative 50% particle size (median value) of the particle size distribution and the particle size distribution width (the cumulative 90% particle size of the particle size distribution and the cumulative 10% particle size of the particle size distribution) By adjusting the (difference), the inrush allowable voltage is improved.

すなわち、本発明は、チタン酸バリウム系磁器組成物を粉砕混合した後、脱水・乾燥し、仮焼して仮焼粉を得、該仮焼粉を粉砕、造粒した後、形成される造粒粉の粒度分布累積５０％粒子径（中央値）が１３０〜１５０μｍで、かつ粒子径分布幅（粒度分布の累積９０％粒子径と累積１０％粒子径との差）が９０〜１２０μｍであり、該造粒粉を成形して得られた成形体を焼成してなることを特徴とする正特性サーミスタである。 That is, the present invention comprises a barium titanate-based porcelain composition that is pulverized and mixed, dehydrated and dried, calcined to obtain a calcined powder, the calcined powder is pulverized and granulated, and then formed. The particle size distribution cumulative 50% particle size (median) of the granule is 130 to 150 μm, and the particle size distribution width (difference between the accumulated 90% particle size and the accumulated 10% particle size of the particle size distribution) is 90 to 120 μm. A positive temperature coefficient thermistor obtained by firing a molded body obtained by molding the granulated powder.

また、チタン酸バリウム系磁器組成物を粉砕混合した後、脱水・乾燥し、仮焼して仮焼粉を得、該仮焼粉を粉砕、造粒した後、形成される造粒粉の粒度分布累積５０％粒子径（中央値）が１３０〜１５０μｍで、かつ粒子径分布幅（粒度分布の累積９０％粒子径と累積１０％粒子径との差）が９０〜１２０μｍとなるようにし、該造粒粉を成形して得られた成形体を焼成することを特徴とする正特性サーミスタの製造方法である。 Also, after pulverizing and mixing the barium titanate-based porcelain composition, dewatering and drying, calcining to obtain calcined powder, crushing and granulating the calcined powder, the particle size of the granulated powder formed The distribution cumulative 50% particle size (median) is 130 to 150 μm, and the particle size distribution width (difference between the cumulative 90% particle size and the cumulative 10% particle size of the particle size distribution) is 90 to 120 μm, A method for producing a positive temperature coefficient thermistor, comprising firing a molded body obtained by molding granulated powder.

さらに、上記の造粒粉を、ふるいを分級装置として分級して得ることを特徴とする正特性サーミスタの製造方法である。 Furthermore, it is a manufacturing method of the positive temperature coefficient thermistor characterized by obtaining said granulated powder by classifying a sieve using a classification apparatus.

そして、上記の仮焼温度が１２００〜１３００℃、焼成温度が１３００〜１４００℃であることを特徴とする正特性サーミスタの製造方法である。 And it is a manufacturing method of the positive temperature coefficient thermistor characterized by said calcining temperature being 1200-1300 degreeC and baking temperature being 1300-1400 degreeC.

本発明の正特性サーミスタ素子は、チタン酸バリウム系磁器組成物を粉砕混合した後、脱水・乾燥し、仮焼して得られた仮焼粉を粉砕、造粒した後、形成される造粒粉の粒度分布累積５０％粒子径（中央値）が１３０〜１５０μｍで、かつ粒子径分布幅（粒度分布の累積９０％粒子径と累積１０％粒子径との差）が９０〜１２０μｍとなるように造粒粉の粒子径を限定して成形し、焼成してなるため、焼成して得られた磁器の焼結体粒子がより均一となり、素子の性質をより均質にすることが可能となる。 The positive temperature coefficient thermistor element of the present invention is formed after the barium titanate-based porcelain composition is pulverized and mixed, dehydrated and dried, and then calcined and granulated calcined powder. The particle size distribution cumulative 50% particle size (median) of the powder is 130 to 150 μm, and the particle size distribution width (difference between the cumulative 90% particle size and the cumulative 10% particle size of the particle size distribution) is 90 to 120 μm. Since the particle size of the granulated powder is limited to the shape, and then fired, the sintered ceramic particles obtained by firing become more uniform and the properties of the element can be made more uniform. .

よって、素子の内部と外部の熱量分布の違いを抑えることができ、構造上の歪みがなくなるため、電圧印加時の突入許容電圧を向上させることができる。 Therefore, the difference in heat distribution between the inside and the outside of the element can be suppressed, and structural distortion is eliminated, so that the inrush allowable voltage at the time of voltage application can be improved.

以下、本発明の実施例について説明する。 Examples of the present invention will be described below.

原料としてＢａＣＯ_３、ＳｒＣＯ_３、ＣａＣＯ_３、Ｐｂ_３Ｏ_４、ＴｉＯ_２、半導体化剤としてＹ_２Ｏ_３、添加物としてＭｎＣＯ_３、ＳｉＯ_２を準備し、所定の組成比で配合した。
さらに、これを湿式で混合した後に脱水乾燥し、本焼成温度以下である１２００℃で２時間仮焼した。
次に、これを湿式粉砕した後にバインダーを加えて造粒し、造粒粉を得た。 BaCO ₃ , SrCO ₃ , CaCO ₃ , Pb ₃ O ₄ , TiO ₂ as raw materials, Y ₂ O ₃ as a semiconducting agent, MnCO ₃ , and SiO ₂ as additives were prepared and blended at a predetermined composition ratio.
Further, this was wet-mixed, dehydrated and dried, and calcined at 1200 ° C., which is lower than the main firing temperature, for 2 hours.
Next, after wet-pulverizing this, a binder was added and granulated to obtain a granulated powder.

得られた造粒粉の粒度分布累積５０％粒子径が１３０〜１５０μｍ、粒子径分布幅（粒度分布の累積９０％粒子径と粒度分布の累積１０％粒子径との差）が９０〜１２０μｍとなるように、ふるいを分級装置として用いて分級した。
分級の方法としては、ふるいを上下に数段積み重ね、上から下に行くほど、メッシュが細かくなるようにし、最上段のふるいに造粒粉を投入して振動を加え、各ふるいにたまった造粒粉を取り出して、表１に示す造粒粉を作製した。 The obtained granulated powder has a particle size distribution cumulative 50% particle size of 130 to 150 μm and a particle size distribution width (difference between the particle size distribution cumulative 90% particle size and the particle size distribution cumulative 10% particle size) of 90 to 120 μm. Thus, the sieve was classified using a classifier.
As a classification method, the sieves are stacked several levels up and down, and the meshes become finer from the top to the bottom. The granulated powder was taken out to produce granulated powder shown in Table 1.

また、比較用として、造粒粉の粒度分布累積５０％粒子径（中央値）が１３０μｍを下回るもの、１５０μｍを超えるもの、粒子径分布幅（粒度分布の累積９０％粒子径と粒度分布の累積１０％粒子径との差）が９０μｍを下回るもの、１２０μｍを超えるものを、ふるいを分級装置として分級し、表１に示す造粒粉を作製した。 For comparison, the granulated powder has a particle size distribution cumulative 50% particle size (median) of less than 130 μm, a particle size distribution of more than 150 μm, a particle size distribution width (particle size distribution cumulative 90% particle size and particle size distribution accumulation Those having a difference of 10% particle diameter) below 90 μm and exceeding 120 μm were classified using a sieve as a classifier to produce granulated powders shown in Table 1.

これを一軸方向に圧力を加えて円柱状（直径２０ｍｍ、厚さ３ｍｍ）に成形し、１３００℃で１時間焼成し、焼結体磁器を得た。 This was uniaxially applied to form a cylinder (diameter 20 mm, thickness 3 mm) and fired at 1300 ° C. for 1 hour to obtain a sintered ceramic.

上記焼結体磁器に電極（下層にＮｉ電極、上層にＡｇ電極からなる二層電極）を形成し、正特性サーミスタ素子（定格：２２５Ｖ、直径１６ｍｍ、厚さ２．５ｍｍ）とした。
この素子で突入許容電圧［Ｖ］の測定を行い、表１の結果を得た。
ここで、上記の測定方法は以下のとおりとした。 An electrode (a two-layer electrode consisting of a Ni electrode in the lower layer and an Ag electrode in the upper layer) was formed on the sintered ceramic, and a positive temperature coefficient thermistor element (rated: 225 V, diameter 16 mm, thickness 2.5 mm) was obtained.
The inrush allowable voltage [V] was measured with this element, and the results shown in Table 1 were obtained.
Here, the measurement method was as follows.

上記の正特性サーミスタ素子に直接、定格電圧を1サイクル２０秒オン／３４０秒オフで印加し、これを５回繰り返した。
その後、電圧を２０Ｖ昇圧し、さらに上記のオン／オフ動作を行い、素子が破壊するまで繰り返した。 The rated voltage was applied directly to the positive temperature coefficient thermistor element at a cycle of 20 seconds on / 340 seconds off, and this was repeated 5 times.
Thereafter, the voltage was increased by 20 V, the above on / off operation was performed, and the operation was repeated until the device was destroyed.

表１は、実施例の造粒粉の粒度分布累積５０％粒子径［μｍ］、粒子径分布幅［μｍ］と、突入許容電圧［Ｖ］との関係を示したものである。 Table 1 shows the relationship between the particle size distribution cumulative 50% particle size [μm], the particle size distribution width [μm], and the inrush allowable voltage [V] of the granulated powder of the example.

表１から分かるように、造粒粉の粒度分布の累積５０％粒子径を１３０〜１５０μｍ、粒子径分布幅を９０〜１２０μｍとすることにより、電圧印加時の突入許容電圧［Ｖ］が向上する。 As can be seen from Table 1, the inrush allowable voltage [V] at the time of voltage application is improved by setting the cumulative 50% particle size of the granulated powder to a particle size distribution of 130 to 150 μm and a particle size distribution width of 90 to 120 μm. .

ここで、累積５０％粒子径が１３０μｍ未満では、造粒粉が細かくなり、成形時の流動性が低下し、金型への充填性が低下して焼結体粒子が均一にならないため、突入許容電圧［Ｖ］が低下する。
一方、１５０μｍを超えると、造粒粉形状が真球からかけ離れた形状となり、成形時の充填性が低下して焼結体粒子が均一にならず、突入許容電圧［Ｖ］が低下するので好ましくない。 Here, when the cumulative 50% particle size is less than 130 μm, the granulated powder becomes fine, the fluidity during molding decreases, the moldability decreases, and the sintered particles do not become uniform. The allowable voltage [V] decreases.
On the other hand, if it exceeds 150 μm, the granulated powder shape becomes a shape far from the true sphere, the filling property at the time of molding is reduced, the sintered particles are not uniform, and the inrush allowable voltage [V] is preferably reduced. Absent.

また、粒子径分布幅が９０μｍ未満のときは造粒粉が均一になり過ぎて、成形時の流動性が低下し、金型への充填性が低下して焼結体粒子が均一にならず、１２０μｍを超えたときは、造粒粉の分布が広がり過ぎて、成形時の流動性が低下し、金型への充填性が低下して焼結体粒子が均一にならず、両者とも突入許容電圧［Ｖ］が低下するので好ましくない。 In addition, when the particle size distribution width is less than 90 μm, the granulated powder becomes too uniform, the fluidity at the time of molding is lowered, the filling property to the mold is lowered, and the sintered particles are not uniform. When the particle size exceeds 120 μm, the distribution of the granulated powder is excessively widened, the fluidity at the time of molding is lowered, the filling property into the mold is lowered, and the sintered particles are not uniform. Since allowable voltage [V] falls, it is not preferable.

そして、上記の焼成温度は１３００〜１４００℃とし、仮焼温度は１２００〜１３００℃として、焼成温度を仮焼温度以上とするのが適当である。
焼成温度が仮焼温度を下回ると、焼結体粒子が均一とならず、素子の性質を均一にすることができなくなり、突入許容電圧が低下するばかりでなく、正特性サーミスタの抵抗値が高くなってしまうので、不適である。 And it is appropriate that said calcination temperature shall be 1300-1400 degreeC, a calcination temperature shall be 1200-1300 degreeC, and a calcination temperature shall be more than a calcination temperature.
When the firing temperature is lower than the calcining temperature, the sintered body particles are not uniform, the element properties cannot be made uniform, the inrush allowable voltage is lowered, and the resistance value of the positive temperature coefficient thermistor is high. Because it becomes, it is unsuitable.

Claims

チタン酸バリウム系磁器組成物を粉砕混合した後、脱水・乾燥し、仮焼して仮焼粉を得、該仮焼粉を粉砕、造粒した後、形成される造粒粉の粒度分布累積５０％粒子径が１３０〜１５０μｍで、かつ粒子径分布幅（粒度分布の累積９０％粒子径と累積１０％粒子径との差）が９０〜１２０μｍであり、該造粒粉を成形して得られた成形体を焼成してなることを特徴とする正特性サーミスタ。 After pulverizing and mixing the barium titanate-based porcelain composition, dehydrating and drying, calcining to obtain a calcined powder, crushing and granulating the calcined powder, and then cumulative particle size distribution of the granulated powder formed The 50% particle size is 130 to 150 μm, and the particle size distribution width (difference between the cumulative 90% particle size and the cumulative 10% particle size of the particle size distribution) is 90 to 120 μm, and is obtained by molding the granulated powder. A positive temperature coefficient thermistor obtained by firing a molded body obtained.

チタン酸バリウム系磁器組成物を粉砕混合した後、脱水・乾燥し、仮焼して仮焼粉を得、該仮焼粉を粉砕、造粒した後、形成される造粒粉の粒度分布累積５０％粒子径が１３０〜１５０μｍで、かつ粒子径分布幅（粒度分布の累積９０％粒子径と累積１０％粒子径との差）が９０〜１２０μｍとなるようにし、該造粒粉を成形して得られた成形体を焼成することを特徴とする正特性サーミスタの製造方法。 After pulverizing and mixing the barium titanate-based porcelain composition, dehydrating and drying, calcining to obtain a calcined powder, crushing and granulating the calcined powder, and then cumulative particle size distribution of the granulated powder formed The granulated powder is molded so that the 50% particle size is 130 to 150 μm and the particle size distribution width (difference between the cumulative 90% particle size and the cumulative 10% particle size of the particle size distribution) is 90 to 120 μm. A method for producing a positive temperature coefficient thermistor, wherein the molded body obtained by firing is fired.

請求項1または２記載の造粒粉を、ふるいを分級装置として分級して得ることを特徴とする正特性サーミスタの製造方法。 A method for producing a positive temperature coefficient thermistor obtained by classifying the granulated powder according to claim 1 or 2 using a sieve as a classifier.

請求項２記載の仮焼温度が１２００〜１３００℃、焼成温度が１３００〜１４００℃であることを特徴とする正特性サーミスタの製造方法。 The method for producing a positive temperature coefficient thermistor according to claim 2, wherein the calcining temperature is 1200 to 1300 ° C and the firing temperature is 1300 to 1400 ° C.