DE1954056C3 - Process for the production of a voltage-dependent resistor - Google Patents

Description

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

The invention relates to a method for the production of a ceramic resistor by sintering a ι essentially of zinc oxide and an additional component that is at least 0.05 to 10 mol percent of one contains alkaline oxide, existing mass at a temperature of 1000 to 1450 ° C.

where V ₁ and V _{a are} the voltages at given currents I ₁ and / "". The desired value of C depends on the type of application in which the resistor is to be used. It is usually desirable that the value of η be so large as possible, since this exponent determines the extent to which the resistances deviate from the ohmic properties.

With conventional varistors containing germanium or silicon p-n bridge diodes, it is difficult to control the C value over a wide range because of its voltage-dependent property of these varistors is not ascribed to the block volume but to the p-n bridge. On the other hand have Silicon carbide varistors have voltage-dependent properties due to the contact of the through a ceramic binder interconnected silicon grains, and the C value is changed by changing a dimension in a direction in which the current flows through the varistors. The silicon carbide varistors however, have a relatively low η value and are fired in a non-oxidizing atmosphere, especially with the aim of maintaining a low C-value, manufactured.

Resistance materials containing zinc oxide and oxides of metals are for example from US Pat. No. 2,887,632. Specifically, US Pat. No. 2,887,632 relates Low resistivity materials or an improved contact rectifier or -transistors, which have a zinc oxide plate as a base plate, which is a material with low specific Resistance is. However, all of the materials proposed in U.S. Patent 2,887,632 have materials ohmic resistance properties. That described in U.S. Pat. No. 2,887,632 Material thus represents a semiconductor (i.e. an ohmic resistance with a low specific Resistance). A combination of ZnO + BaO can be present in it; the material will however not sintered, as it is expressly required to only heat it at a temperature below 900 ° C, so that no material is obtained that can be used without further measures (such as special contacting, etc.) is voltage dependent. The given temperature

.renze is mandatory, since the prevention of sintering taltung _{A wejtere Ausges} of the invention is

ims of zinc oxide is expressly desired. _{in that} , the _mass essentially consists of zinc oxide,

In GB-PS 11 30108 a voltage-dependent 0.1 to 3.0 mol percent barium oxide and 0.1 to 3.0 mol

• _he resistance from 99.95 to 90.0 mole percent _{per cent of c} i _neä oxide of the group: strontium oxide,

Ztokoxid and 0.05 to 10.0 mole percent of an additional ₅ lead oxide and cobalt oxide. Advantage of this

Lomoonente described, which is an oxide from the voltage-dependent resistor that the

Group: iron oxide (Fe ₂ O ₃ ), aluminum oxide, bismuth _n . _Value can be increased further.

oxide magnesium oxide, calcium oxide, nickel oxide, is _a further embodiment of the invention

Cobalt oxide, niobium oxide, tantalum oxide, zirconium oxide, tungsten characterized in that the composition in essential "Moxide, cadmium and chromium oxide (Cr ₂ O _{3) 10} DAR _union s _au zinc oxide, from 0.05 to 10.0 mole percent of Bariumstellt · known ceramic body is at high _ox jd _; 0.05 to 8.0 mole percent bismuth oxide and 0.05 temperatures sintered. The voltage-dependent up to 8.0 mole percent of an oxide of the group: Stron properties of the well-known ceramic resistance tium oxide and lead oxide consists. An advantage of this, however, is achieved only through a voltage-dependent resistor is nichtohm- that in combination's contact between the sintered body and the ₁₅ nation a high η value and a low C-value silver electrodes. The sintered body itself has none being obtained.

nonlinear properties. Another embodiment of the invention exists

In the USA.-Patent 28 92 988 a tem- is that the mass consists essentially of zinc oxide,

Oerature-dependent resistance described, which 0.1 to 3.0 mol percent barium oxide, 0.1 to 3.0 mol-

L _{n contains} barium oxide as a component; this Wi- ₂₀ percent bismuth oxide and 0.1 to 3.0 mole percent one

The stand does not have any voltage-dependent (non-oxides of the group: strontium oxide and lead oxide).

ohmic) properties. The advantage of this voltage-dependent resistor is

The object of the present invention was to ensure that the C value is reduced and the M value

Method of the type mentioned at the beginning for the production is properly increased.

lune a voltage-dependent ceramic resistance is used ₂₅ A further embodiment of the invention is characterized to find Hes with non-ohmic characteristics, in that the composition consists essentially of, in particular by a high "value as a result of zinc oxide, from 0.05 to 10.0 mole percent barium oxide, s is marked "iner composition and can be adjusted from 0.05 to 8.0 mole percent of lead oxide and 0.05 to 8.0 MOI C value. percent of an oxide from the group strontium oxide and

The underlying object is thus consists overall ₃₀ cobalt oxide. The advantage of this is that the only additional component used is the Ba-dependent resistor, which also uses a high rium oxide, whereby the sintered body itself can be obtained / i-value.

receives a strongly voltage-dependent resistance. Another embodiment of the invention exists

Fin has such a voltage-dependent resistance that the mass consists essentially of zinc oxide, If the measure of the same is a non-ohmic 0.1 to 3.0 mol percent barium oxide, 0.1 to 3.0 mol-Ästand. Therefore its C-value can be changed. Percent lead oxide and 0.1 to 3.0 »mole percent one without worsening the η value, by separating the oxides from the group: strontium oxide and cobalt oxide exists between the opposing surfaces. Advantageous with this voltage-dependent is ÄXt. A shorter distance leads to a resistance that is an extremely high »value

is ÄXt. A shorter distance leads
• A clearer C value of 40 can be obtained.

One embodiment of the invention consists in that these and other objects of the invention are that the mass consists essentially of zinc oxide and is explained in the following description and also consists of 0.1 to 30 mole percent barium oxide. In this drawing, in which the only figure shows a tension-dependent resistance, it is advantageous to have a partial cross-sectional view of a spandass according to the invention which has a higher value. ₄₅ »independent. ^^^ *« ^^ · _the

Another embodiment of the invention is characterized Before e.ner-going e.nzelne ^Descriptio '^ "8.The that the mass in the essential by the invention intended spannungsabhanfe.gen ficheTaus ^{g of} zinc oxide, from 0.05 to 10.0 mole percent barium -. resistances to their construction is described with reference ^ oxide and 0 05 to 8.0 mole percent of calcium oxide, the aforementioned Abb.ldung the Ze.ehnung explained Dr advantage of this voltage-dependent resistor _50, in which 10 "^ f ^ S, is that the stability at ambient temperatures resistance as a whole designated _{u "d} e, improve ektrische Be.astungsdauertest ^^^^ Si ^ S

A further embodiment of the invention consists in that the mass is essentially made of zinc oxide. ^he ^^ Si 3.0 mole percent barium oxide and 0.1 to 3.0 mole- way manufactured ^u " ^d ₍ ^h ^^ ⁿ ^ 'th JkieTn Platt \ v» nt ralriiimnxid hesteres a round, square or rectangular riauc.

'Tissrsiiss.-np.bh. ^ G', wide. ^ «^ _{5 and} ^ t ^^ t

The stand is that the stability for ambient temperatures 2 and 3 is secured by means of connecting means

rcn and the electrical endurance test in addition to 60 en £ Lotungod. «^ ^ _{N by one as} such

is properly improved. ^ Known ceramic technology can be produced. the

mmmism

mmsrnsrnm

Group: strontium oxide, lead oxide and coba.toxide ^ %% \ ^^ "* £ ^^ _d shape sown. An advantage of this s _S now _g sabha _nglg s ^ ^ Stun gesSn and then in o'fen to room-resistance that the 'value is increased. &

the

»5

pressed at a pressure of 10 'to 10 ⁸ Pa, pressed bodies are sintered in air at a given temperature for 1 to 3 hours and then cooled in the furnace to room temperature (about lfi to 30 ° C).

The available sintering temperature is in terms of d <»n electrical resistivity, the Non-linearity and stability are determined and lies in the range from 1000 to 1450 ° C.

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

It is advantageous if the sintered body on the opposite surfaces by one Abrasive powder such as silicon carbide with a particle size of 10 to 50 μτη is abraded.

The sintered bodies are provided on their opposite surfaces with electrodes in one and appropriate manner such as by electroplating method, vacuum evaporation method, plating method provided by spraying or silver painting processes.

The voltage-dependent properties are practically not affected by the types of electrodes used influenced, however, by the thickness of the sintered body. In particular, the C value fluctuates in the Relation to the thickness of the sintered body, while the η value is almost independent of the thickness. This certainly means that the voltage-dependent property affects the block volume itself and cannot be traced back to the electrode.

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

The voltage-dependent resistors according to the invention have a high temperature resistance and service life at full load, the test of which 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 high resistance to moisture it is advantageous that the voltage-dependent resistances obtained are in a moisture-proof Resin such as an epoxy resin and phenol resin can be embedded in a manner known per se. Preferred illustrative embodiments of the invention follow.

Tert disk is on the opposite surfaces thereof by silicon carbide of one particle size of 28 (im abraded. The preserved p, it sintered Disc has a size of 14 mm in diameter and 1.5 mm in thickness. Commercially available Silver point electrodes are placed on the opposite surfaces of the sintered disk Spread attached. Then, lead wires are attached to the silver electrodes by soldering. the temperature (around 15 to 30 ° C). The total electrical properties of the resistors obtained are shown in Table 1. It is easy to see that the zinc oxide sintered bodies that Barium oxide incorporated in an amount of 0.05 to 10.0 mol percent, for a voltage-dependent Resistance can be used, and that in particular the addition of barium oxide in one The amount of 0.1 to 3.0 mole percent makes the stress nonlinear property even more excellent. ° Table 1

(Mol
percent) C.
(at
ImA) π (MoI-
percent) C.
(at
ImA) π 0.05
0.1
0.2
0.5
1 420
280
70
40
65 3.2
5.4
6.2
7.0
6.4 2
3
5
8th
10 90
120
200
285
380 5.7
5.2
4.6
3.9
3.3

Example 2 example 1

Raw materials composed of 99.5 mol% of zinc oxide and 0.5 mol% of barium oxide are mixed, dried, calcined and pulverized in the same manner as in Example 1. The pulverized mixture is pressed in a mold into a molding 17.5 mm in diameter and 5 mm in thickness at a pressure of 5 x 10 ⁷ Pa.

The pressed body is sintered in air at 1350 ° C. for 1 hour and then in an oven to room temperature cooled down. The sintered disc becomes a thickness on its opposing surfaces as indicated in Table 2, by silicon carbide with a particle size of 28 (im abraded. The sanded disc is with the electrodes and lead wires on the opposite surfaces in a manner similar to that in Example 1. The electrical properties of the resistors obtained are shown in Table 2; the C-values vary approximately in relation to the thickness of the sintered disk, while the η value is essentially independent of the thickness. It's easy to understand that the stress nonlinear properties of the resistors are related to the sintered body are to be ascribed to themselves.

A mixture of zinc oxide and barium oxide in a composition given in Table 1 is ^{mixed for 6c 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 molding 17.5 mm in diameter and 2.5 mm in thickness at a pressure of 5 x 10 ⁷ Pa. The pressed body is exposed to air at 1350 ° C

Table 2

Thickness (mm) C (at 1 mA) π Beginning (4.1)
3.5 107
93 7.1
7.0 3.0 79 6.9 2.5 65 7.2 2.0 53 7.0 1.5 40 7.0 1.0 26th 6.9

Example 3

Zinc oxide to which barium oxide and calcium oxide are incorporated in a composition given in Table 3 is processed into voltage-dependent resistors by the same method as in Example 1. The resistances obtained are tested according to the methods used in the electronic components. The service life test at full load is carried out at 7C ^D C ambient temperature and 0.5 watt load for 500 hours. The heat cycle test is held by 5 times repeating the cycle, wherein these resistances at 85 ° C ambient temperature for 30 minutes, rapidly - cooled to -20 ⁰ C and 30 minutes, maintained at this temperature is performed. Table 3 shows a difference in C value and value between resistors before and after the load life test. It can be readily seen that the combination of barium oxide and calcium oxide is effective as an additive for electrical and environmental strength.

Table 3

IJaO CaO Life test
at stress Jn (V ₀ ) Warming cycle test Jn (Vo) (Mole percent) (Mole percent) J C (Vo) -9.2 J C (Vo) -8.6 0.05 0.05 -8.5 -6.2 -9.0 -6.2 0.05 0.5 -7.2 -6.0 -7.1 -5.9 0.05 8th -7.0 -8.7 -5.9 -8.7 0.5 0.05 -6.2 -8.6 -7.9 -8.8 0.5 8th -7.0 -7.1 -8.0 -7.1 10 0.05 -6.9 -6.5 -6.2 -6.3 K) 0.5 -6.7 -9.3 -5.9 -9.0 K) 8th -9.0 -4.3 -8.7 -4.2 0.1 0.1 -4.2 -2.9 -4.8 -2.2 0.1 0.5 -3.8 -3.7 -3.2 -4.0 0.1 3 -4.1 -4.5 -3.3 -3.0 0.5 ο, ι -2.6 -4.4 -4.6 -2.6 0.5 3 -2.7 -3.6 -4.7 -2.8 3 0.1 -3.0 -2.9 -3.4 -3.0 3 0.5 -3.7 -4.8 -3.6 -3.9 3 3 -4.9 -1.1 -4.0 -1.3 0.5 0.5 -1.2 -0.8

Example 4

Zinc oxide with the additions from Tables 4 and 5 becomes voltage-dependent resistances processed using the same procedure as in Example 1. The H values of the resistances obtained are in see the combination of barium oxide with one of the following oxides: strontium oxide, cobalt oxide and lead oxide as additives leads to an excellent stress nonlinear property and eir Remarkably excellent value can be obtained by additional combination of barium

Tables 4 and 5 reproduced. It is easy to 45 oxide and lead oxide with strontium oxide or cobalt oxide

Table 4

BaO SrO CoO PbO C. 5.0 (Mole percentage) (Mole percent) (Mole percent) (Mole percent) (at 1 mA) 9.2 0.05 0.05 600 4.9 0.05 0.5 - - 330 10 0.05 8th - - 590 9.5 0.5 0.05 - - 60 5.0 0.5 8th - - 58 10 10 0.05 - - 540 4.9 10 0.5 - - 350 10 10 8th - - 525 15th 0.1 0.1 - - 300 11th 0.1 0.5 - - 290 14th 0.1 3 - - 320 14th 0.5 0.1 - - 50 11th 0.5 3 - - 48 16 3 0.1 - - 135 11th 3 0.5 - - 120 1 3 - - - 150

(Continued from table 4)

10

BaO SrO CoO PbO C. 18th (Mole percent) (Mole percentage) (Mole percent) (Mole percent) (at J mA) 4 ,: 0.5 0.5 _ 42 9.1 0.05 - 0.05 520 5, ( 0.05 - 0.05 300 9 ,: 0.05 - 8th 570 9, ' 0.5 - 0.05 57 4 ,: 0.5 - 8th 56 9 ,! 10 - 0.05 500 4, ' 10 - 0.5 325 9 10 - 8th 500 14th 0.1 - 0.1 - 285 10 0.1 - 0.5 - 310 13th 0.1 - 3 - 300 13th 0.5 - 0.1 - 47 10 0.5 - 3 - 46 15th 3 - 0.1 110 10 3 - 0.5 .— 125 16 3 - 3 - 130 5 ,: 0.5 - 0.5 40 9.C 0.05 - - 0.05 700 4, i 0.05 - - 0.5 350 9, ' 0.05 - - 8th 620 9, ' 0.5 - - 0.05 72 5, ( 0.5 - - 8th 63 11th 10 - - 0.05 570 5, Ί 10 - - 0.5 385 11th 10 - - 8th 550 15th 0.1 - - 0.1 325 10 0.1 - - 0.5 310 13th 0.1 - - 3 350 13th 0.5 - - 0.1 65 11th 0.5 - - 3 53 14th 3
^ - - 0.1 150 10 3 - - 0.5 135 16 3 - - 3 170 0.5 - 0.5 48

Table 5

BaO SrO CoO PbO C.
(at 1 mA) π (Mole percent) (Mole percent) (Mole percent) (Mole percent) 600 8.0 0.05 0.05 0.05 340 7 ^ 9 0.05 0.05 - S. 570
550
530
515 6.1
8.0
7.9
8.3 0.05
0.05
10
10 8th
8th
0.05
0.U5 - 0.05
8th
0.05
8th 500
490
275
290 8.0
8.4
13th
14th IO
IO
0.1
0.1
Λ ι 8th
8th
0.1
0.1 - 0.05
8th
0.1
3 300
300
125
110 14th
14th
15th
17th 0.1
0.1
3
3 3
3
0.1
0.1 - 0.1
3
0.1
3 135 14th 3 3
- * - 0.1 150
39 14th
25th 3
0.5 3
0.5 -. 3
0.5 490 8.3 0.05 - 0.05 0.05 480 8.4 0.05 - 0.05 8th 500 8.3 0.05 - 8th 0.05 520 7.8 0.05 - 8th 8th 480 7 (1 10 - 0.05 0.05

(Continued from table 5)

BaO SrO CoO PbO C. 8.1 (Mole percent) (Mole percent) (Mole percent) (Mole percent) ^ at 1 niA) 6.4 10 - 0.05 8th 450 7.0 10 - 8th 0.05 450 12th 10 - 8th 8th 500 12th 0.1 - 0.1 0.1 270 12th 0.1 - 0.1 3 285 14th 0.1 - 3 0.1 280 13th 0.1 - 3 3 270 15th 3 - 0.1 0.1 100 12th 3 - 0.1 3 105 15th 3 - 3 0.1 125 24 3 - 3 3 115 0.5 - 0.5 0.5 35

Example 5

Zinc oxide with the additions from Table 6 becomes
voltage-dependent resistors according to the same
Process as in Example 1 processed. 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 make a remarkably excellent one τι value and at the same time leads to a lower C value.

Table ό

BaO Bi ₂ O ₃ PbO SrO C. η (Mole percent) (Mole percent) (Mole percent) (Mole percent) (at I mA) 7.0 0.05 0.05 0.05 __ 400 6.9 0.05 0.05 8th - 420 6.8 0.05 8th 0.05 - 430 6.0 0.05 8th 8th - 450 6.5 10 0.05 0.05 - 300 7.0 10 0.05 8th - 310 7.2 10 8th 0.05 - 305 7.4 10 8th 8th - 325 13th 0.1 0.1 0.1 - 195 12th 0.1 0.1 3 - 200 11th 0.1 3 0.1 - 200 11th 0.1 3 3 210 13th 3 0.1 0.1 95 14th 3 0.1 3 98 12th 3 3 0.1 110 13th 3 3 3 120 20th 0.5 0.5 0.5 25th 7.0 0.05 0.05 0.05 380 7.2 0.05 0.05 8th 390 6.9 0.05 8th 0.05 350 6.0 0.05 8th 8th 400 7.2 10 0.05 0.05 380 7.1 10 0.05 8th 375 7.2 10 8th 0.05 350 6.8 10 8th 8th 310 12th 0.1 0.1 0.1 200 13th 0.1 0.1 3 195 12th 0.1 3 . 0.1 180 13th 0.1 3 3 200 13th 3 0.1 0.1 85 13th 3 0.1 3 95 12th 3 3 0.1 80 13th 3 3 3 90 26th 0.5 0.5 0.5 25th

1 sheet of drawings

Claims (10)

Patent claims: 1. A method for producing a ceramic resistor by sintering a material consisting essentially of zinc oxide and an additional component which contains at least 0.05 to 10 mol percent of an alkaline earth oxide at a temperature of 1000 to 1450 ^° C., characterized in that the only additional component Barium oxide is used, which gives the sintered body itself a highly voltage-dependent resistance. 2. The method according to claim 1, characterized in that that the mass consists essentially of zinc oxide and 0.1 to 3.0 mole percent barium oxide consists. 3. The method according to claim 1, characterized in that that the mass consists essentially of zinc oxide, 0.05 to 10.0 mole percent barium oxide ao and 0.05 to 8.0 mole percent calcium oxide. 4. The method according to claim 1, characterized in that that the mass consists essentially of zinc oxide, 0.1 to 3.0 mole percent barium oxide • nd consists of 0.1 to 3.0 mole percent calcium oxide, as 5. The method according to claim 1, characterized in that that the mass consists essentially of zinc oxide, 0.05 to 10.0 mole percent barium oxide and 0.05 to 8.0 mole percent of an oxide from the group consisting of strontium oxide, lead oxide and cobalt oxide. 6. The method according to claim 1, characterized in that the mass consists essentially of Zinc oxide, 0.1 to 3.0 mole percent barium oxide and 0.1 to 3.0 mole percent of an oxide of the group: Is made up of strontium oxide, lead oxide, and cobalt oxide. 7. The method according to claim 1, characterized in that the mass consists essentially of Zinc oxide, 0.05 to 10.0 mole percent barium oxide, 0.05 to 8.0 mole percent bismuth oxide, and 0.05 to •, 0 mole percent of an oxide from the group: stronium oxide and lead oxide. 8. The method according to claim 1, characterized in that the mass consists essentially of Zinc oxide, 0.1 to 3.0 mole percent barium oxide, •, 1 to 3.0 mole percent bismuth oxide and 0.1 to J.0 mole percent of an oxide from the group: strontium oxide and lead oxide. 9. The method according to claim 1, characterized in that the mass consists essentially of Zinc oxide, 0.05 to 10.0 mole percent barium oxide, 0.05 to 8.0 mole percent lead oxide, and 0.05 to t, 0 mole percent of an oxide of the group: strontium oxide and cobalt oxide. 10. The method according to claim 1, characterized in that that the mass consists essentially of zinc • oxide, 0.1 to 3.0 mol percent barium oxide, 0.1 to S.0 mole percent lead oxide and 0.1 to 3.0 mole percent of an oxide from the group: strontium oxide and cobalt oxide. 60 Such a method is known from GB-PS 1130108. Various voltage-dependent resistors such as silicon carbide varistors, selenium rectifiers and germanium or silicon p-bridge diodes are widely used for voltage stabilization or the current used in electrical circuits. The electrical properties of such voltage dependent resistance are given by the relationship - (τ