WO1994024680A1

WO1994024680A1 - Positive characteristic thermistor

Info

Publication number: WO1994024680A1
Application number: PCT/JP1994/000622
Authority: WO
Inventors: Hiroshi Sasaki; Hiroshi Inagaki; Takuji Okumura; Masatoshi Tamura; Katsuhiko Sugisawa
Original assignee: Kabushiki Kaisha Komatsu Seisakusho
Priority date: 1993-04-14
Filing date: 1994-04-14
Publication date: 1994-10-27
Also published as: KR960701453A; EP0694930A1; EP0694930A4

Abstract

A thermistor having a small specific resistance ς25 at room temperature, a large α and stable characteristics. The semiconductor which constitutes the main body of the thermistor is a BaTiO3 perovskite-type compound. The quantity of Ti is smaller than that determined by the stoichiometric ratio, which has been preferably in excess conventionally.

Description

Specification

Positive characteristic mistake

Technical field

The present invention relates to a positive-characteristic temperature sensor, and more particularly to a composition of a thermistor body.

Background art

In general, porcelain consisting B a T i 0 ₃ system base perovskite-type compound is a dielectric, piezoelectric, pyroelectric, have electrical have utility value properties such as abnormal resistance, widely various electronic devices Used.

Inter alia B aT i 0 _3, Y, and Nd, etc. ◦. 1 to 0. The added oxide semiconductors 3at% is because it has a large positive temperature coefficient, it referred to as PTC thermistor evening. In the positive characteristics, the temperature range having a large positive temperature coefficient can be adjusted by adding Sr, Pb, etc., so that the temperature can be measured and overcurrent can be prevented. It must be in a wide variety of fields, such as circuit elements for demagnetization and low-temperature heaters.

Further, for practical use the room temperature resistivity shown in FIG. 3 (hereinafter / o ₂ 5), temperature coefficient of resistance (hereinafter alpha), the composition surface to fit the purpose of resistance change width (hereinafter]), controlled from the preparation surface Must.

For example, in order to increase the temperature coefficient of resistance α and to increase the resistance change width J, a method of adding Mn, which is an element that controls the surface state of crystal grain boundaries (Japanese Patent Publication No. 41-12146, No. Publication 42 No. 3855) and No. method (JP-B 51- 19599 the addition of S i 0 ₂ in order to lower the room temperature resistivity p _25), a method of an excess of T i amount (JP 41 one 21,869 No. ) Etc. << Known.

Incidentally, when providing a positive characteristic mono- thermistor of BAT i 0 ₃ based on practical, that the room temperature ratio resistors P ₂ r is small, the resistance temperature coefficient α is large, it is required that the resistance change width J force "high However, there is a positive correlation between and and there is a limit of (aZl o gp. ₅ ) ~ 10 even if you try to obtain a small power and a large power of < ₂₅ . In addition, in the conventional positive characteristics as described above, it is necessary to include a high vapor pressure and Pb in the material. There was a problem that a large amount of Pb vapor was generated and the toxicity to the environment was high. Disclosure of the invention

A first object of the present invention, one force, low room temperature resistivity p _25, can resistance temperature coefficient α is large, there is provided a mono mistakes evening with stable characteristics.

A second object of the present invention is to provide a highly reliable positive-characteristic thermistor with low power consumption, no generation of Pb vapor, and high reliability.

To achieve the above first object, the present invention, in the semi-conductor composition of B a T i 0 ₃ perovskite type compounds constituting the mono- thermistor body, the better to you in excess T i amount It is characterized in that the composition that has been set is a composition in which the Ti amount is less than the stoichiometric ratio.

That is, it is characterized by comprising a thermistor main body made of a rhodium titanate-based semiconductor formed so as to satisfy the following formula, and a power supply electrode attached to the thermistor main body.

(B — _x - _y S _{x My)} T _iz 0 _{3 + nA}

0≤x x, 0 x y x 1, 0.99≤z x 1, 0 ≤π <0.002 (Equation)

S: at least one element selected from Sr, Sn, Zr, Ca, Pb

M: Nb, Ta, Bi, Sb, Y, La, Nd, W, Th, Ce, Sm, Gd,

At least one element selected from Dy

A: At least one element selected from Mn, Fe, Cu, Cr, F, CI, Br, K, and V

The present inventors have repeated various experiments by changing the composition ratio, and as a result, have found that a composition in which the Ti amount is less than the stoichiometric ratio is better, and the present invention has been made by paying attention to this. as hereinbefore, by using the above composition, and smaller room temperature resistivity p _25, alpha is possible force to provide a mono thermistor with a large listening stable characteristics.

In the above composition, the element of S mainly has an action of controlling the Curie temperature, the element of 主として has an action of mainly converting the composition into a semiconductor, and the element of Α controls the surface state of the crystal grain boundary. It is believed to be something.

Further, in order to achieve the second object, the present invention is characterized in that the composition of the semiconductor constituting the thermistor body is constituted by the following titanate / <calcium-lium-thiocyanate-based semiconductor. ( ^{B a} ixy ^{C a} x ^Y y) ^{T i} (l + z) ° 3 ⁺ P ^{S 1} ° 2 ^{+ q Mn}

0.01≤x ≤0.2, 0.002 ≤y ≤0.006, 0.001 ≤z ≤0.010, 0.005 ≤p≤0.

03 0.0005≤q ≤0.0015 (Equation) In other words, in conventional barium titanate-strontium titanate-based semiconductors, the addition of Pb was stopped and titanium was added in excess of the stoichiometric ratio. Features.

The present inventors have conducted various experiments by changing the composition, and as a result, have found that the use of the above composition makes it possible to obtain a positive characteristic thermistor with low power consumption. Is made by paying attention to this.

In the above composition, Ca has the effect of refining the crystal grains and improving the withstand voltage characteristics. The reason why the composition range is set to 0.01 ≤ x ≤ 0.2 is that when X is smaller than 0.01, there is no effect of improving the characteristics, and when X exceeds 0.2, the specific resistance of the element becomes large and the practicality is lost.

Y has an effect of imparting semiconductivity to titanium titanate. In order to reduce the specific resistance to a practically low value (10 to 1 kQ * cm), its composition range must be within the range of 0.002 ≤ y ≤ 0.006.

Excess Ti content than the stoichiometric composition has a large effect on the crystal grain size and the temperature coefficient of resistance of the device, and therefore has the greatest effect on power consumption during energization. Here, the composition range of T i is set to 0.001 ≤z ≤0.010 because the temperature coefficient of resistance is smaller for a table with a value of less than 0.001. Therefore, the element resistance at the time of applying a voltage is reduced, and the power consumption during energization is increased. For such a reason, the above range is determined.

Further, S i 0 ₂ lowers the sintering temperature, the effect of suppressing abnormal grain growth of crystal grains. The reason for setting 0.005 ≤p≤0.03 is that bananas smaller than 0.005 have insufficient effect of suppressing abnormal grain growth, and larger than 0.03, and conversely, cause abnormal grain growth of crystal grains.

Mn has the effect of increasing the temperature coefficient of resistance above the Curie temperature. However, since the addition of Mn also increases the specific resistance, the composition range must be 0.0005≤q≤0.0015 in order to obtain the above effect within the practical range of the specific resistance of the element (l kQ * cm or less). Ah

• Brief description of the drawing

FIG. 1 is a diagram showing a positive characteristic thermistor according to the first embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the composition ratio of the positive temperature coefficient thermistor of the embodiment of the present invention and the conventional example, and the specific resistance at room temperature and the temperature coefficient of resistance.

Fig. 3 shows anomalous resistance at positive temperature thermistors.

FIG. 4 is a diagram showing a positive characteristic thermistor according to the second embodiment of the present invention.

FIG. 5 is a diagram showing a circuit for measuring power consumption in a positive temperature coefficient thermistor according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1

FIG. 1 is a diagram showing a positive characteristic thermistor according to an embodiment of the present invention.

The positive characteristics of the thermistor are characterized in that the composition of the thermistor body 1 is configured as shown in the following equation.

^{(B a} 0.7737 ^{S r} 0.2221 ^Y 0.0042 ^{} T i} 0.9955 ° 3 ⁺ ^{0-00 1Mn} (Equation) In other words, this positive temperature coefficient thermistor is composed of A first electrode layer 2a, 2 made of a Ni vapor-deposited layer formed so that the edge comes to a position slightly entering from the outer peripheral edge, and first electrode layers 2a, 2b on this upper layer. Second electrode layers 3a and 3b containing silver as a main component and formed so that their edges coincide with each other.

Next, a manufacturing process of the positive temperature coefficient thermistor will be described.

First, T i C 1, was diluted with distilled water so that the volume of the stock solution is doubled, a portion of the T i C 1 ₄ is hydrated, concentration of T i 1 mole per 239. 6 g T i C 17] Japanese. Here, the concentration was quantified by Coulomb analysis.

Next, the T1s Ji 7 hydrate 238. 3 g (T i: 0. 994 mol) were collected and the T i C 1 ₄ 7] solution was added further distilled water 400 g.

Further, 1145 g of 12.7 wt% BaC 1 _Q aqueous solution (Ba: 0.595 mol), 16.5 vt% SrC127] solution 479.2 g (Sr: 0.297 mol), 4.5 3 wt% YC 1 ₃ aq 104. 7 g (Y: 0. 0156 mol) was formulated, four The aqueous solutions were mixed.

Then, 75 ° C ± 0 was maintained at _{5 ° C 16. 7wt% H 2} C 2 0 4 ( oxalic acid) aqueous solution _{_{1440 g (H 2 C 2 0}} 4: 1. 902 mol). The混台solution over 4 hours beat drops, as a coprecipitate the (Ba S rY) T i O (C 2 0 ^) 2 · 4Η 9 0 becomes oxalates.

After filtration and washing with water, the oxalate was calcined at 1150 ° C. for 1 hour. The M n (N0 ₃₎ "the calcined powder (B a S r Y) T i 0 3 After 0.1 mol% added to the total Monore number, slurry one for 1 hour wet grinding in a planetary ball mill I got

Then, the granulated powder was reduced to 60 m or less by a spray drier, formed into pellets by a hydraulic press, and fired at 141 CTC for 1 hour to obtain semiconductor porcelain. An electrode was attached to this porcelain and the temperature resistance characteristics were measured. The results are shown in Table 1.

Table 1 Example · Temperature of comparative example · Resistance characteristics

Example 2

Next, the composition of the thermistor body 1 was configured as shown in the following equation. B ^a 0.7744 ^{S r} 0.2217 ^Y 0.0039 ^{} T i} 0.9961 ° 3 ^{+ 0} " ^{00 1Mn} (Formula) Next, the manufacturing process of the positive temperature ^coefficient thermistor will be described.

As in Example 1, the T i C 1 stock solution was diluted with distilled water and the concentration was

245 g T g of T i C 1 ₄ hydrate was prepared, and this T i C 1 ₄ hydrate 122. 1 g (T i: 0. 499 mol) were collected and the T i C 1 ₄ ΤΚ solution was added further distilled water 200 g.

Further to the aqueous solution 12. 8wt¾ B a C 1 ₂ solution 573. 3 g (B a: 0. 400 mol), 16. 6wt% S r C 127K solution 239. 7 g (S r: 0. 149 mol), 3. 50wt% YC 1 ₃ 7} solution 51. 8g. (Y: 5. 98x10- 3 moles) were mixed, 75 ° C ± 0 5. Was maintained at _{_{C 16. 7wt% H 2 C 2}} 0 4 aq _{_{720. 3 g (H 2 C 9}} 0 4: 0. 954 mol) was added dropwise over the mixture 2.5 hours, to give the oxalate salt Was.

Then, a device was prepared in the same manner as in Example 1, and the characteristics were measured. The results are shown in Table 1.

Example 3

Next, the composition power of the thermistor body 1 was configured as shown in the following equation.

⁽ Ba 0.7731 ^{S r} 0.2228 ^Y 0.0041 ^{) T 1} 0.9964 ^Ο 3 ^{+ 0} · ^001Μη (Equation) A thermistor having this composition was prepared in the same manner as in Example 2, and the characteristics were measured. Table 1 shows the results.

Example 4

Next, the composition of the thermistor body 1 was configured as shown in the following equation.

⁽ Ba 0.7707 ^{S r} 0.2254 ^Y 0.0039 ^{} T i} 0.9972 ° 3 ^{+ 0} · ^001Μη (Equation) A thermistor element having this composition was prepared in the same manner as in Examples 2 and 3.

Shown in 1.

Comparative example A

Next, as a comparative example, the composition of the thermistor body 1 was configured as shown in the following equation. (Ba _{0 7778} S r _{0 2180} Y _{0 0042} ) T i _{1 0033} O ₃ + ◦. ΙΜ ΙΜη (Formula) This composition exceeds the upper limit of the composition range of T i.

Next, the manufacturing process of the positive characteristic thermistor will be described.

First, the T i C l ₄ hydrate concentration of T i 1 mole per 244. 5 g, T i Ji 1 _tetrahydrate 243. 4 g: the (T i 0. 9954 mol), further distilled water 400 g was added to obtain a TiC 1 aqueous solution.

And concentration of the T i C aqueous solution混台to B a C 1 ₂ 7 solution following each solution The mixing amount is the same as in Example 1. The method of manufacturing the device after the dropwise addition of the mixed aqueous solution is also the same as in Example 1. Table 1 shows the measurement results of the characteristics of the thermistor element. Comparative Example B

Next, as a comparative example, the composition of the thermistor body 1 was configured as shown in the following equation.

^{(B a} 0.7703 ° ^r 0.2249 ^Y 0.0048 ^{Τ ι} 0.9879 ^Ο 8 ^{+ 0} ^{'00 1Μη} (equation) This composition exceeds the lower limit of the composition range of Τ i.

Next, when manufacturing this positive temperature coefficient thermistor, the temperature was maintained at 70 ° C ± 0.5 ° C.

Except for using _₂ C ₂ 0 ₄ (oxalate) 7K solution formed as in Example 1. Table 1 shows the measurement results of the characteristics of the rice thermistor element as Comparative Example B.

As is clear from Table 1, of the claims, the composition range of T i ₇ : 0.99 ≤ z When a positive temperature coefficient thermistor element having a composition satisfying 1 is manufactured, P ₂₅ is 1 2 It was found to be as small as 5 to 26.5 Ωcm and α was 24.00% or more, and that J had characteristics in the order of six digits. As shown the results of measurement of the relationship between T i quantity (T i Z (B a + S r + Y)) and αΖ Ι ogp ₂₅ in FIG. 2, in the conventional example (Comparative Example), 1 og Ρ ₂₅ However, according to the present invention, it is possible to take a value that is twice or more.

Thus it is possible according to the present invention in which [rho ₂₅ to obtain a positive characteristic thermistor with excellent smaller than α is large.

Example 5

FIG. 4 is a diagram showing a PTC thermistor according to the embodiment of the present invention.

This positive temperature coefficient thermistor is characterized in that the composition of the thermistor body 1S has a composition ratio as shown in the following table, and is constituted by potassium titanate-calcium titanate semiconductor shown below.

^{(B a} lxy ^{C a} x ^Y y) ^{T 1} (1 ₊ ζ) ° 3 ⁺ Ρ ^{S 1} ° 2 ^Μη

0.01≤χ ≤0.2, 0.002 ≤y ≤0.006, 0.001 ≤ζ ≤0.010, 0.005 ≤ρ≤0.

03 0.0005≤q ≤0.0015 (Formula) Table 2

In other words, this positive characteristic ceramic is formed such that the main body 1S of the above composition, which is composed of titanium titanate, and the upper surface and the T® have an edge at a position slightly entering from the outer peripheral edge. A first electrode layer 2a, 2b formed of a Ni vapor-deposited layer, and a second layer mainly composed of silver formed on the first electrode layer 2a, 2b so as to match the edge force of the first electrode layer 2a, 2b. And two electrode layers 3a and 3b.

First, dried blended commercial _{_{T i 0 o, BaC0 3,}} CaC0 3 Contact and Y ₂ 0 ₃ powder having an average particle diameter of 0. 3 ~ 2 m at the rate of previous tables after wet mixing, 10◦ 0 It was calcined at a temperature of ~ 120 CTC for 4 hours. The resulting blended S i 0 2 and _{Mn (NOg) 2 ♦ 6H 2} 0 aqueous solution having an average particle diameter of 1 m to calcined powder was wet-mixed ♦ Kona碎. An organic binder was added to the slurry and granulated by a spray drier. The obtained granulated powder is formed by a hydraulic press to a density of 2.5-3.Og / cm ³ , and then fired at 135 CTC for 1 hour in the air to have a diameter of 20 mm and a thickness of 2. 5 Obtained barium titanate-based semiconductor porcelain. Commercially available Ag electrodes were printed and printed on both end surfaces of the semiconductor porcelain, and the specific resistance and power consumption were measured. Here, the power consumption was measured using a measurement circuit as shown in FIG. In this measurement circuit, the positive characteristic error signal 10 is connected to the power supply 12 via the load resistor 11, and this connection can be turned on and off by the switch 13. The voltage at both ends of the positive temperature coefficient thermistor 1 測定 is measured by the connected voltmeter 14, and the voltage is measured by the The current flowing is measured. In this way, the voltage at both ends of the positive characteristic thermistor 10 and the current flowing through the positive characteristic thermistor 10 are measured to calculate the power consumption. Here, the power consumption P (W) was obtained by the following equation.

P (W) = V _p (v) x I (A)

In the above table, compositions Nos. 1 to 5, 8, and 9 indicate the present invention, and compositions Nos. 6, 7, 10, and 11 indicate comparative examples.

By comparing composition Nos. 1 to 5 with compositions Nos. 6 and 7, the amount of excess Ti 0 ₂ was 0.001 to O. Olmol (total Ti 0 _¾ 100.1 -101.0 mol), It can be seen that a small power consumption equal to or less than the power consumption (3.0 W) of composition No. 11 can be obtained. If the amount of excess Ti is 0.001 mol or less or O.Olmol or more, the power consumption is 3. Ow or more.

Also, when the amount of excess Ti 0 ₂ was fixed at 0.3 mol (total Ti 0 ₉ 100.3 mol) and the amount of Ca added was changed (composition Nos. 2, 8, 9, 10), the amount of Ca added If it exceeds 20 mol, the specific resistance increases rapidly, making it impractical. Also, when the amount of Ca added is 20 mol or less. Specific resistance of less than 1ΚΩ · cm can be obtained, and power consumption is as low as 3.0W or less.

In the composition not containing Pb, Ba, Ca, T i, Y, Μη, S i 0. By optimizing the composition range of Pb, the power that can not be obtained without adding Pb in the past, the power to achieve very low power consumption can be obtained, and Pb is not included, so Pb vapor is generated during manufacturing The problem could be solved.

Industrial applicability

As described above, according to the first aspect of the present invention, than chemical stoichiometric ratio T i amount the composition of B a T i 0 ₃ system base perovskite-type compound constituting the mono- miss evening body not To obtain a positive characteristic thermistor with a small P _{25 and a} large α due to the addition

Further, according to the second aspect of the present invention, since the composition of the semiconductor constituting the semiconductor body is composed of barium titanate-calcium titanate-based semiconductor containing no Pb, Pb vapor is emitted during firing. And a positive temperature coefficient thermistor with low power consumption during energization can be provided.

0

Claims

The scope of the claims

(1) A ceramic body made of a titanic acid-based semiconductor formed so that the composition satisfies the following formula:

A positive-characteristic thermistor comprising a power supply electrode attached to the thermistor body.

^{^{^{^ B a lxy S x M y}}} T i z ° 3 + nA

0≤x <1, 0 <y <1, 0.99≤z <1, 0 ≤n <0.002 (expression)

S: at least one element selected from Sr, Sn, Zr, Ca, Pb

M: Nb, Ta, Bi, Sb, Y, La, Nd, W, Th, Ce, Sm, Gd,

At least one element selected from D y

A: At least one element selected from Mn, Fe, Cu, Cr, F, Cl, Br, K, and V

(2) a thermistor body made of barium titanate-calcium titanate semiconductor having a composition satisfying the following formula:

(Ba _x _ _y Ca _x Y _y ) T i + Og + p S i. ₂ + q Mn

0.01 ≤ x ≤ 0.2, 0.002 ≤ y ≤ 0.006, 0.001 ≤ z ≤ 0.010, 0.005 ≤ p ≤ 0. 03 0.0005 ≤ q ≤ 0.0015 (Equation) A power supply electrode attached to the thermistor body Positive characteristic thermist evening.