DE1954056A1 - Barium modified voltage variable zinc oxide resistor - Google Patents

Description

195A056

M 2714

PATENT ADVOCATE

Dr..lng. HANS RUSCHKB

O'pJlng. H £ 1N2 ÄÖÜLAff

BERLIN 33

Matsushita Electric Industrial Co., Ltd., Kadoma, Osaka, Japan

Barium modified voltage variable zinc oxide resistor

The invention relates to a voltage-variable ceramic resistance mass, which consists essentially of zinc oxide and barium oxide as additives. The barium modified voltage variable zinc oxide resistor With regard to the non-linear voltage properties, further addition of strontium oxide, lead oxide, Calcium oxide, cobalt oxide and bismuth oxide improved.

The invention relates to masses of a voltage variable resistor -Ceramic material with a non-ohmic resistance and in particular masses of varistors that contain zinc oxide and because of of the block volume of the same have a non-ohmic resistance.

Various voltage-variable resistors such as silicon carbide varistors, selenium rectifiers and germanium or silicon -p-n bridge diodes are widely used to stabilize the

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Voltage and Current Used in electrical circuits. The electrical characteristics of such a voltage-variable Resistance is created through the relationship

V ⁿ
I = ("5") expressed,

where V is the voltage across the resistor, I that through the resistor flowing current, C a constant corresponding to the voltage at a given current and the exponent η a number larger than 1 is. The value of η is calculated by the following equation:

η =

where V ₁ and V _{2 are} the voltages at given currents I ₁ and Ig. The desired value of C depends on the type of application in which the resistor is to be used. Usually the aim is for the value of η to be as large as possible, since this exponent determines the extent to which the resistances deviate from the ohmic properties.

With conventional varistors, the germanium or silicon p-n -Bridge diodes included, it is difficult to determine the C value via a wide range to regulate, because of the voltage characteristic of these varistors is not assigned to the block volume, but to the pn bridge. On the other hand, silicon carbide varistors have voltage-variable properties due to the contact of the through a ceramic binder interconnected silicon grains, and the C value is determined by changing a dimension in a direction in which the current flows through the varistors » regulated. The silicon carbide varistors, however, have a comparatively large number low η-value and are made by burning in a non-oxidizing atmosphere, especially with the iSiel one to maintain low C-value.

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One object of the present invention is a mass a voltage-variable resistor body with the same non-ohmic property due to the block volume, which is in the C-value can regulate.

Another object of the present invention is a mass of a voltage-variable resistance body, which by a high η value is excellent.

These and other objects of the invention are presented in the following Description explained, as well as with reference to the accompanying drawing, in which the only figure is a partial cross-sectional view a voltage-variable resistance body according to the invention represents.

Before a detailed description of the invention desired voltage-variable resistors should explain their structure with reference to the aforementioned figure of the drawing be, in which with 10 a voltage-variable resistor is designated as a whole, which is an active element sintered body with a pair of electrodes 2 and 3 applied to the opposite surfaces thereof are ^ This sintered body 1 is produced in a manner to be explained and has any shape such as that of a round, square or rectangular plate. Lead wires 5 and 6 are lj \ e / tend attached to the electrodes 2 and 3 by a Lanyard * 4 like a solution or something similar.

A voltage-variable resistor according to the invention contains a sintered body of a mass consisting essentially of 90.0 to 99.95 mol- # zinc oxide and 0.05 to 10.0 mol- # barium oxide consists. Such a voltage variable resistor has a non-ohmic resistance because of its bloc lumen. Therefore, the C-value can be changed without deteriorating the η-value by changing the distance between the opposite Surfaces changes. A shorter distance leads to a lower one C value.

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The higher η value can be obtained when said sintered body consists essentially of 97.0 to 99.9 molar zinc oxide and 0.1 to 3.0 molar barium oxide according to the invention.

According to the invention, the stability at room temperature and the Electrical life at full load can be improved if the sintered body is made of 82.0 to 99.9 mol- $ zinc oxide, 0.05 to 10.0 moles of barium oxide and 0.05 to 8.0 moles of calcium oxide.

Furthermore, the stability at room temperature and the electrical The service life under full load is greatly improved if this sintered body is essentially made of 94.0 - 99 * 8 Zinc oxide, 0.1 to 3.0 moles of barium oxide, and 0.1 to 3.0 Calcium oxide consists.

According to the invention, the η value is increased when this sintered body consisting essentially of 82.0 to 99.9 mole # zinc oxide, 0.05 to 10.0 moles of barium oxide and 0.05 to 8.0 moles of one of the following Oxides: Strontium Oxide, Lead Oxide, or Cobalt Oxide.

The η value is also increased when said sintered Body is composed of a mass consisting essentially of 94.0 to 99.8 mol- # zinc oxide, 0.1 to 3.0 mol- # barium oxide, and 0.1 to 3.0 mol $ of one of the following oxides: strontium oxide, Lead oxide or cobalt oxide.

According to the invention, a combination of a high η value and low according to the C value can be obtained when this sintered body is made of a mass which essentially contains zinc oxide, 0.05 to 10.0 mol- # Barium oxide, 0.05 to 8.0 mol- # bismuth oxide and 0.05 to 8.0 mol- # one of the following oxides: strontium oxide or lead oxide.

Furthermore, the C value is lowered and the η value is increased extraordinarily if this sintered body is made of a mass that essentially consists of 91.0 to 99.7 mol- # zinc oxide and 0.1 to 3.0- # barium oxide, 0.1 to 3.0 mol # bismuth oxide and 0.1 to 3.0 # one of the following oxides: strontium oxide or lead oxide,

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According to the invention, the high η value can also be obtained when this sintered body is a mass consisting essentially of 7 ^, 0 · up to 99.85 mol- 56 zinc oxide, 0.05 to 10.0 mol- # barium oxide and 0.05 to 8.0 MoI-Ji lead oxide and 0.05 to 8.0 MoI-Ji any of the following Oxides: Strontium Oxide, or Cobalt Oxide, is made up.

Furthermore, the extremely high η value can be obtained, if this sintered body is made of a mass consisting essentially of 91.0 to 99.7 mol of zinc oxide and 0.1 to 3.0 mol of barium oxide, 0.1 to 3.0 moles of lead oxide and 0.1 to 3.0 moles of one of the following Oxides: Strontium Oxide, or Cobalt Oxide, is made up.

The sintered body 1 can be made by a ceramic technique known per se -getting produced. The starting materials in the The above-described masses are in a wet mill mixed so that homogeneous mixtures are produced. The mixtures are dried and in a form of desired dimensions

o solutions and shape at a pressure of 100 kg / cm to 1 000 kg / -

2
cm pressed. The pressed bodies are sintered in the air at a given temperature for 1 to 3 hours and then cooled in the furnace to room temperature (about 15 to 30 C).

The available sintering temperature is determined with regard to the electrical resistivity, which determines non-linearity and stability, and is in the range from 1000 to 1450 ° C.

The pressed bodies are preferred in a non-oxidizing one Atmospheres such as nitrogen and argon are sintered when a reduction in electrical resistivity is desired is.

The mixtures can initially be calcined at 700 ° C. to 1000 ° C. and pulverized in the subsequent pressing step for easier processing. The material to be pressed can mixture with a suitable binder such as water, polyvinyl alcohol, etc. are mixed.

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It. Is advantageous if the sintered body to the opposite lying surfaces by an abrasive powder such as silicon carbide abraded with a particle size of 300 to 1500 mesh will.

The sintered bodies are on their opposite surfaces with electrodes in an available and suitable manner such as by electroplating method, vacuum evaporation method, metalization method by spraying or silver painting method Mistake.

The voltage variable properties are practically nonexistent influenced by the types of electrodes used, but by the thickness of the sintered bodies. In particular, the fluctuates C value in relation to the thickness of the sintered body while the η value is almost independent of the thickness. This certainly means that the voltage-variable property has an effect on the Block volume itself and not due to the electrode.

Lead wires can be attached to the electrodes in a conventional manner be attached by conventional low melting point solder. It is convenient to use a conductive one Adhesive containing silver powder and resin in an organic solvent to connect the lead wires to the electrodes.

The variable voltage resistors according to the invention have a high temperature resistance and service life under full load, their test was carried out at 70 ° C with a load of 500 hours will. The η-value and C-value do not change noticeably after the heating cycles and the test for service life at full Load. To achieve a high resistance to moisture, it is advantageous that the voltage variables obtained Resistances in a Peuohtigkelts-strong hair; iie one Epoxy resin and phenolic resin in a soldered manner • be embedded,

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Preferred illustrative embodiments "of" follow here Invention:

example 1

A device made of zinc oxide and barium oxide in a composition given in Table 1 is mixed for 3 hours in a wet mill. The mixture is dried and then calcined ^{at 700 ° C. for 1 hour.} The calcined mixture is pulverized by the motor-driven ceramic mortar for 30 minutes and then pressed in a mold into a molded piece 17.5 mm in diameter and 2.5 mm in thickness at a pressure of 500 kg / cm.

The pressed body is sintered 1 hour in air at 1350 ° C and then furnace cooled to room temperature (about 15 to 30 ⁰ C). The sintered disk is abraded on the opposite surfaces thereof by silicon carbide having a particle size of 600 mesh. The sintered disk obtained has a size of 14 mm in diameter and 1.5 mm in thickness. Commercially available silver point electrodes are brush attached to the opposing surfaces of the sintered disk. Then, lead wires are attached to the silver electrodes by soldering. The electrical properties of the resistors obtained are shown in Table 1. It can be quickly seen that the sintered zirioxide bodies, which contain barium oxide incorporated in an amount of 0.05 to 10.0 mol- $, can be used for a voltage-variable resistor, and in particular the addition of barium oxide in a Amount from 0.1 to 3 * 0 mol- $ which makes the nonlinear stress property even more excellent.

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C. 2 Table 1 (mol- *) C. η (at ImA) η (at ImA) 420 2 90 5.7 0.05 280 5.2 3 120 5.2 ο, ι 70 5.4 5 200 4.6 0.2 40 6.2 8th 285 5.9 0.5 65 7.0 10 380 3.3 1 6.4 example

Composed of 99.5 mol $ zinc oxide and 0.5 mol $ barium oxide Raw materials are mixed, dried, calcined and pulverized in the same manner as in Example. The pulverized Mixture becomes a molding of 17.5 mm in a mold

Diameter and 5 mm thickness pressed at a pressure of $ 00 kg / cm,

The pressed body is sintered in air at 1550 C for 1 hour and then cooled in the oven to room temperature. The sintered Disk is given a thickness as shown in Table 2 on its opposite surfaces by silicon carbide a particle size of βΟΟ mesh ground. The ground disc is opposite to the electrodes and lead wires Surfaces provided in a similar manner as in Example 1. The electrical properties of the resistors obtained are shown in Table 2; the C values fluctuate approximately in relation to the thickness of the sintered disk, while the η value is essentially independent of the thickness. It is easy to understand that the nonlinear stress properties of the resistors are related to the sintered body itself are attributable.

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- 9 Example j5 (at ImA) η 7.1 Table 2 107 7.0 Thickness (mm) C. 93 6.9 initially (4.1) 79 - 7.2 3.5 65 7.0 3.0 53 7.0 2.5 4o 6.9 2.0 26. · 1.5 1.0

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Zinc oxide incorporating barium oxide and calcium oxide in a composition given in Table 3 becomes the voltage variables Resistors processed according to the same procedure as in Example 1. The resistances obtained are according to the methods that are used in the electronic components. The service life test at full load is carried out at an ambient temperature of 70 ° C and a load of 0.5 watt for 500 hours. The heating cycle test is repeated 5 times of the cycle in which these resistors are at 85 ° C ambient temperature Held for 30 minutes, quickly cooled to -20 C and kept at this temperature for 30 minutes. Table 3 shows a difference in C value and η value between Resistances before and after the load life test. It can quickly be seen that the combination of barium oxide and calcium oxide is effective as an additive for electrical and environmental strength.

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CaO Table 3 lifespan Heating cycle ^ n (fo) BaO (MoI- ^) Test on tion test -8.6 (Mole- $) at Belas 4 0 {%) -6.2 0.05 4 ^c (^) -9.2 -9.0 -5.9 0.05 0.5 -8.5 -6.2 -7.1 -8.7. 0.05 8th -7.2 -6.0 -5.9 -8.8 0.05 0.05 -7.0 -8.7 -7.9 -7.1 0.5 8th -6.2 -8.6 -8.0 -6.3 0.5 0.05 • -7.0 -7.1 -6.2 -9.0 ' 10 0.5 -6.9 -6.5 -5.9 -4.2 10 8th -6.7 -9.3 -8.7 -2.2 10 0.1 -9.0 -4.3 -4.8 -4.0 0.1 0.5 -4.2 -2.9 -3.2 -3.0 0.1 3 -3.8 -3.7 -3.3 -2.6 0.1 0.1 -4.1 -4.5 -4.6 -2.8 0.5 3 -2.6 -4.4 -4.7 -3.0 0.5 0.1 -2.7 -3.6 -3.4 -3.9 3 0.5 -3.0 -2.9 -3,, 6 -1.3 3 3 -3.7 -4, p -4.0 3 0.5 -4.9 -1.1 -0.8 0.5 -1.2 Example 4

Zinc oxide with the additions from Tables 4 and 5 becomes voltage variants Resistors processed according to the same procedure as in Example 1. The η values of the resistances obtained are shown in the table 4 and 5 reproduced. It's quick to see that the combination of barium oxide with one of the following oxides strontium oxide, cobalt oxide and lead oxide as additives to an excellent one nonlinear stress property leads and a remarkable excellent η-value can be obtained by add.Kt & V'öhe Combination of barium oxide and lead oxide with strontium oxide or .Cobalt Oxide.

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Tabel

• BaO SrO CoO 'PbO C η

(MoI-Ji) (MoI-Ji) (Mol- #). (MoI-Ji) (at ImA)

0.05 0.05 0.05 0.5 0.05 8th 0.5 0.05 0.5 8th 10 0.05 10 0.5 10 8th 0.1 0.1 0.1 0.5 0.1 3 0.5 0.1 0.5 ' 3 3 0.1 3 0.5 3 3 0.5 0.5 0.05 - 0.05 - 0.05 - 0.5 - 0.5 - 10 - 10 - 10 ο, ι - ο, ι - 0.1 - 0.5 - 0.5 - 3 3 3 ___

0.05 0.05 8

0.05

0.05

0.5

0.1

0.5 3

0.1 3

0.1 0.5 3
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600 330 590 60 58 540 350 525 300 290 320 50 48 135 120 150 42 520 300 570 57 56 500 325 500 285 310 300 47 46 UO 125 130

5.0 9.2

'4.9 10

9.5 5.0 10

4.9 10

15th

11th

14th

14th

11th

16

11th

18 4.8 9.0 5.0 9.5 9.7 4.5 9.8 4.7 9 14 10 13 13 10

15 10

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Table 4 (continued)

BaO SrO CoO PbO C η t) (Mol- $) (Mol- $) (at ImA)

0.5 0.5 40 16

0.05 - - 0.05 700 5.3

0.05 - - 0.5 350 9.0

0.05 - - 8 620 4.8

0.5-0.05 72 9.7

0.5 - - 8 63 9.7

10 - - 0.05 570 5.0

10 - - 0.5 385 11

10 - - 8 550 5.4

0.1 - - 0.1 325 11

0.1 - - 0.5 310 15

0.1 3 350 10

0.5 - - 0.1 65 13

0.5 - - 3 53 13

3 - - '0.1 150 11

3 - - 0.5 135 14

3 - - 3 170 10

0.5 - - 0.5 48 16

Table 5 BaO SrO CaO PbO

C. η (at ImA) 600 8.0 340 7.9 570 6.1 550 8.0 530 7.9 515 8.3 500 8.0 490 8.4

0.05 0.05 0.05 0.05 0.05 8th 0.05 8th 10 0.05 10 0.05 10 8th 10 8th

0.05

0.05

0.05

0.05

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Table 5 (port setting)

BaO SrO CaO PbO C. η (MoI-Ji) (Mole-0) (Mol- *) (Mol- #) (at ImA) ο, ι 0.1 ___ 0.1 275 13th ο, ι 0.1 3 290 14th 0.1 3 ο, ι 300 14th 0.1 3 3 300 14th 3 0.1 0.1 125 15th 3 ο, ι 3 110 17th 3 3 0.1 135 14th 3 3 3 150 14th 0.5 0.5 0.5 39 25th 0.05 0.05 0.05 490 8.3 0.05 0.05 8th 480 8.4 0.05 8th 0.05 500 8.3 0.05 8th 8th 520 7.8 10 0.05 0.05 480 7.0 10 0.05 8th 450 8.1 10 8th 0.05 450 6.4 10 8th 8th 500 7.0 ο, ι 0.1 0.1 270 12th 0.1 0.1 3 285 12th ο, ι 3 0.1 280 12th 0.1 3 3 270 14th 3 0.1 0.1 100 13th 3 0.1 3 105 15th 3 3 0.1 125 12th 3 3 3 115 15th o, 5 —__ 0.5 0.5 35 24

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Example 5

Zinc oxide with the additions from Table 6 becomes voltage variables Resistors processed according to the same procedure as in Example 1. The electrical properties of the resistors obtained are shown in Table 6. It is easy to see that the combination of barium oxide and bismuth oxide with lead oxide or strontium oxide as additives to a remarkably excellent one η value and at the same time leads to a lower C value.

Table 6

BaO Bi ₂ O ₃ PbO SrO C. η (MoI-Ji) (Mol-i) (Mo l- #) (Mol-iO (at ImA) 0.05 0.05 0.05 400 7.0 0.05 0.05 8th 420 6.9 0.05 8th 0.05 430 " 6.8 0.05 8th 8th 450 6.0 10 0.05 0.05 300 6.5 10 0.05 8th 310 7.0 10 8th 0.05 305 7.2 10 8th 8th 325 7Λ 0.1 0.1 0.1 195 - 13th 0.1 0.1 3 200 12th 0.1 3 0.1 200 11th 0.1 • 3 3 210 11th 3 0.1 0.1 --_ 95 13th 3 0.1 3 98 14th 3 3 0.1 110 12th 3 3 3 120 14th 0.5 0.5 0.5 ... 25th 20th 0.05 0.05 ... 0.05 38Ο 7.0 0.05 0.05 8th 390 7> 2 0.05 8th ... 0.05 350 6.9 0.05 8th wmmnm 8th 400 6.0.

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Table 6 (continued)

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-BaO Bi 0 PbO SrO C. η (MoI- *) (MoI-Ji) (Mole- $) (Mole- $) (at ImA) 10 0.05 0.05 38O 7.2 10 0.05 8th 375 7.1 10 8th 0.05 350 7.2 10 8th 8th 310 6.8 0.1 0.1 'ο, ι 200 12th 0.1 ο, ι 3 195 13th 0.1 3 0.1 180 12th 0.1 3 3 200 13th 3 0.1 0.1 85 13th 3 0.1 , 3 95 13th 3 3 0.1 80 12th 3 3 -, - 3 90 ι5 0.5 0.5 —— 0.5 25th 26th

- patent claims -

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Claims (1)

- 16 - M 2714 Patent claims: Ceramic, voltage-variable resistance mass, essentially consisting of zinc oxide and 0.05 to 10.0
Barium oxide. 2, ceramic voltage-variable resistance mass according to claim 1, wherein the mass consists essentially of zinc oxide and 0.1 to 3.0 Mo 1- $ barium oxide. J5. Ceramic variable voltage resistance mass according to claim 1, wherein the mass is further 0.05 to 8.0 mole # of one of
following oxides: strontium oxide, lead oxide, calcium oxide or
Contains cobalt oxide. 4. Ceramic variable voltage resistance mass according to claim 2, wherein the mass is further 0.1 to J> 0 mole # of one of
following oxides: strontium oxide, lead oxide, cobalt oxide or
Calcium oxide. 5. Ceramic variable voltage resistance mass according to claim 1, wherein the composition further comprises 0.05 to 8.0 mol # bismuth oxide and 0.05 to 8.0 mole # of one of the following oxides: strontium oxide or lead oxide. 009827/1170 - 17 - M 2714 6. The ceramic variable voltage resistance composition of claim 2, wherein the composition further comprises 0.1 to 2.0 moles of bismuth oxide and 0.1 to 3.0 mole of one of the following oxides: strontium oxide or lead oxide. 7. Ceramic variable voltage resistance mass according to claim 1, wherein the composition further comprises 0.05 to 8.0 mol # lead oxide and 0.05 to 8.0 mole # of one of the following oxides: strontium oxide or cobalt oxide. 8. Ceramic voltage variable. Resistance mass according to claim 2, wherein the composition further comprises 0.1 to 3.0 mol- # lead oxide and 0.1 to 3.0 mole of one of the following oxides: strontium oxide or cobalt oxide. Dr.Pa./Br. 0 0 9827/1170 It Blank page