DE2103489C3 - Resistance paste - Google Patents

Description

3 4

has little difference in electrical resistance. Usually this glass coating can be underneath

Excellent use of a glass coating paste before and after coating with glass

being. that a finely divided glass frit in a liquid

The solution to this problem occurs when a counter-carrier contains and fired at one temperature

Standing paste of the type mentioned, 5, which is lower than the temperature at which the

that according to the invention the glass frit has also been fired 0.1 to resistance paste beforehand.

Contains 17.0 percent by weight Ag _{2 O.} The liquid carrier can be in the composition

The Wiüerstandspaste of the invention results after the largely fluctuate. Any liquid carrier can be used for Applying to the support and melting can be used for this purpose, e.g. B. water, Resistance created by a small change in the io organic solvent, with or without thickening electrical Resistance in the state before and medium, stabilizing agents or the like, e.g. B. methyl, after glass coating is excellent. With ethyl, butyl, propyl or higher alcohols, the The resistor paste of the invention is a large corresponding ester, such as the carbitol acetates, pro range the electrical conductivity adjustable, with bionate etc., the terpene, and liquid resins, z. B. the temperature coefficient is relatively small. 15 spruce oil, Λ turpentine oil and other liquids

According to one embodiment of the invention, it makes up without limitation, the function of the liquid AgoO content of the basic composition of the glass carrier mainly being a liquid frit from 0.1 to 3.0 percent by weight. An Ag ₂ O content or paste-like mass of the dispersed mixture of the glass frit below 0.1 percent by weight leads to the formation of
no noticeable improvement in the change in the 20 The liquid carrier may contain or together electrical resistance. be put out of volatile carrier to the fast

According to a further embodiment of the invention to promote settling after application, or that is what the Ag ₂ O content of the base composition, carriers, waxes, thermoplastic resin such as the glass frit make up 3.0 to 17.0 percent by weight. Contain ethyl cellulose or waxy material. A resistance paste composed in this way results in 25 which are inherently heat-flowable, so that a particularly small temperature coefficient of the mass can be applied to a thermal insulator or at a higher electrical resistance and a relatively fringe th temperature, in order to change the electrical resistance by an immediately Contact with the insulating glass cover. To solidify an Ag ₂ O content of the glass frit over a substrate.

17.0 percent by weight causes devitrification of the 30 It is important to determine the particle size of the cadmium oxide

Glass frit and affects the bond strength. powder and also that of the glass frit. Advantage-

Another solution to the above problem with sticky mean particle sizes of the cadmium oxide

a resistance paste of the type mentioned in powder form are between 0.05 and 20 μm; advantageous

takes place in that according to the invention the glass frit particle size of the glass frit between 0.5 and 30 µm.

also 0.1 to 3 percent by weight Ag ₂ O and 35. It is preferred that the viscosity of the finished paste

Contains 3 to 8 percent by weight Al ₂ O _3. With a 500 to 2000 poise for the stencil process

such Resistar.dspaste will have a glaze resistance.

with a relatively high electrical resistance and the resistance applied to the ceramic base

a small change in electrical resistance Stand paste is, if necessary, dried to

obtained by a glass coating. 40 to remove solvents from the liquid carrier,

The invention is further developed in the drawings and then in an electric furnace at a temperature

explained in which the temperature at which the glass frit melts is fired,

F i g. 1 is a plan view of a glaze resistor below to bond the cadmium oxide powder particles so that

Using the resistor paste of the invention is to adhere it firmly to the insulating pad,

and FIG. 45 The following examples are given by way of illustration

F i g. 2 is an enlarged cross-section of the glaze of the invention.

Resistance along line 1-1 of FIG. 1 is. . .

In the F i g. 1 and 2, the number 3 means an example.

Resistance layer made of finely divided cadmium oxide- Different glass frits in a shown in Table I-

powder 4 and a composition that binds this cadmium oxide powder are made according to a known

the glass frit 5. Glass frit technique. The glass frits are

A ceramic insulating carrier 6 contains the through a wet ball mill to an average Resistance layer 3 firmly bonded to it. The particle size of 1.5 microns is pulverized. The melted one Glass frit 5 also acts as an adhesive to the average particle size of the cadmium used Attaching the resistive layer 3 to the 55 oxide powder is 0.8 microns. Though it's purpose-built 6. The carrier 6 is moderately sized with a pair of electrodes 2, the particle sizes fairly matching before applying the resistor paste. Closing / u halls in order to achieve reproducible results If the resistance layer 3 is obtained with a glass, the actual particle size is not coating 7 coated. The resistance paste can be crucial.

by a suitable process, such as screen printing or 60 A mixture of 2.H 5. Cadmiumo \ idpuiver and Brush it onto the carrier 6 with a 1.2 g applied pair of silver electrodes 2 applied liquid carrier containing 10 percent by weight of ethyl. The applied resistance paste is cellulose in Uutylcarhitoracetat contains, under Verdcr Air heated to form the opposing layer 3 using an automatic shredding mixer, which adheres firmly to the insulating support 6. 65 machine well mixed to make a contradicting paste

The resistance layer 3 is produced with an im. The resistance paste is applied underneath

Commercially available material for a glass over / 'i "using a screen printing process on I-orsteritveneheii. the one lower softening temperature r insulating pads, each of which has a pair of silver

electrodes at a distance of 0.5, 1.0, 1.5, 2.0 or 3.0 mm from each other. The width of the applied resistor paste is 0.5, 1.0, 1.5, 2.0 or 3.0 mm. As a result, the applied resistor paste has a resistor active area of 0.5 0.5 mm, 1.0 χ 1.0 mm, 1.5 1.5 mm, 2.0 2.0 mm and 3.0>; 3.0 mm. The electrical resistance this square area is defined as a surface resistivity (kQ / D).

The resistor paste is heated in a tunnel furnace having a temperature schedule, so that a sample at 760 ^c C 6 minutes may be heated. The fired resistor film has the specific surface resistance given in Table I and is approximately 18 μm thick.

The glass coating paste is made by mixing 30% by weight of one of the above-mentioned vehicles similar carrier and 70 percent by weight glass frit powder, that of 75 percent by weight lead oxide, 11.2 percent by weight Boron oxide, 10.5 percent by weight aluminum oxide and 3.3 percent by weight silica.

The glass coating paste produced in this way is applied to the resistor film by a screen printing process, ^{dried at 120 °} C. for 10 minutes and then fired ^{at 450 ° C. by means of a tunnel oven.} The difference in electrical resistance before and after coating with glass paste is shown in Table 1 in Samples 1 to 4. In this connection, it can be seen that a glaze resistor when silver oxide with glass frit is incorporated has a lower change in electrical resistance than the glaze resistor using glass frit without silver oxide.

Example 2

The resistor paste is prepared using a glass frit powder in one of the tables shown in Table 1 The composition shown in exactly the manner shown in Example 1. The resistance paste is after a Screen printing process on a forsterite insulating pad

Table I.

with a pair of electrodes 1 mm apart. The applied resistor paste has a width of 1 mm. The applied resistor paste is dried and fired in exactly the same way as in Example 1. The fired resistive film has a thickness of about 18 microns and a surface resistivity and a temperature coefficient of resistance (TK in ppm / ° C) as in Table I. Due

ίο from this information it is clear that the use of a Glass frit with silver oxide makes it possible to adjust the temperature coefficient over a wide range change from a negative value to a positive value, and the workable surface resistance to expand. So z. B. the use of

17 weight percent silver oxide (sample 8) has a surface resistivity that is around an order of magnitude is lower than that without using silver oxide (Sample 1).

Example 3

A mixture of 2.8 g of cadmium oxide powder and 1.2 g of glass frit powder as shown in Table II is used with 1.2 g of liquid carrier in the same manner as wi; at Example 1 mixed well. The resistor film is made using exactly the same resistor paste from Example 1 and at a thickness of about

18 μπι produced. Table II shows a specific one Surface resistance of these resistive films.

The resistive film is covered with a glass coating in a manner exactly corresponding to Example 1.

A difference in electrical resistance in the state before and after coating is shown in Samples 9 through 12 of Table II are shown for resistance range. From this information It is clear that the change in electrical resistance due to the overstress using a glass frit containing silver oxide is improved

sample Glass composition (percent by weight) Spec. Upper resistance change (%) BiO ₃ ZnO Ag ₁ O surfaces Glass composition (percent by weight) B ₂ O, ZnO Al ₁ O, Ag ₁ O 0.25mm ¹ 1.0 mm ¹ 2.25mm ¹ 4.0 mm * 1.0 mm ¹ 2.25mm ¹ 9.0 mm ¹ TX in 11.6 13.7 0 11.6 13.7 7.0 0 -5.3 +9.2 + 14.5 +18 +4.0 +6.1 +22 ppm / ⁰ C 11.6 13.7 0.1 resistance PbO 11.6 13.7 7.0 0.1 -1.0 + 1.8 + 2.2 + 2.2 -1.3 -1.4 + 2.2 No. PbO 11.6 13.7 1.0 kO / D 67.7 11.6 13.7 7.0 1.0 +1.0 + 1.0 + 1.0 + 1.2 -0.5 -0.6 + 1.2 1 74.7 11.6 13.7 3.0 0.23 67.6 11.6 13.7 7.0 3.0 -2.1 -1.8 - 1.8 - 1.5 + 1.0 +0.8 - 1.5 -200 2 74.6 11.6 13.7 4.0 0.23 66.7 -2.0 - - -200 3 73.7 11.6 13.7 5.0 0.22 64.7 -2.0 - -200 4th 71.7 11.6 13.7 10 0.20 -2.0 -190 5 70.7 11.6 13.7 17th 0.115 - -2.0 - - - -140 6th 69.7 0.053 - 40 7th 64.7 0.029 Spec. Upper
flat*"" Change in resistance (%) + 60 8th 57.7 0.019 resistance +180 table II kQ / ö 0.25mm ¹ 4.0 mm ¹ sample 2.35 -1.5 +7.5 2.35 +0.5 -1.4 No. 2.30 -0.4 -0.6 0.9 mm ' 9 1.90 + 1.2 +0.8 +9.0 10 1 sheet of drawings -1.5 11th +0.8 12th +0.8

Claims (4)

an enamel resistor paste, consisting of finely divided patent claims: precious metals such as gold, platinum, palladium, silver and fine glass frit. However, such an email 1. Resistance paste, which is expensive as a homogeneous dispersion resistance paste, although it is due to the sion of finely divided solid components in an inert 5 properties of the resistors formed from them Carrier liquid is present and is superior to melting on. A ceramic carrier is applied, as is usually a glaze resistor through solid constituents 40 to 90 percent by weight of an application of resistance paste on an insulating mixture, which is made from 20 to 92 percent by weight of the ceramic carrier with fine silver cadmium oxide formed thereon and 8 to 80 electrodes by weight. The applied resistance percent consists of finely divided glass frit, as well as 10 to paste is then at a suitable temperature to contain 60 percent by weight of carrier liquid, producing a with the ceramic carrier firmly melted the finely divided glass frit from 83.0 to 99.9 weight-bonded resistance layer. The percent of a basic composition consists, the resistance layer formed is generally provided with 60 to 80 percent by weight of PbO, 8 to 16 percent by weight of a glass coating in order to ensure a long life _{percent B 2} O ₃ and 12 to 24 percent by weight ZnO. The glass coating is characterized in that the application of a glass coating paste to the glass frit also produces a 0.1 to 17.0 weight base layer. The glass coating paste contains a _{percentage of Ag 2 O.} usually consists of one in a carrier liquid 2. Resistance paste according to claim 1, characterized in »o dispersing glass frit powder. Their firing temperature indicated that the Ag ₂ O content is the basic lower than the temperature of the resistor paste. Composition of the glass frit 0.1 to 3.0 Ge The problem with the coating process is the weight percent. that the electrical resistance of the coated resistors 3. Resistance paste according to claim 1, characterized in that the standcchicht differs from that of the original consistency in that the Ag ₂ O content of the base layer, which has no coating, differs, composition of the glass frit 3.0 to 17.0 Ge The difference makes it difficult to determine the weight percentage (the rest of the glass frit base - glaze resistance in large numbers with constant /: us composition). to establish the highest values. 4. Resistance paste, which is a homogeneous dispersion from USA.-Patent 35 51 195 is a sion of finely divided solid components in an inert 30 resistance paste for the production of conductive carrier liquid and known for melting on glazes on ceramic carriers, which have a ceramic carrier is applied as a homogeneous dispersion of 40 to 90 percent by weight of solid constituents 40 to 90 percent by weight of one of finely divided solid constituents, consisting of a mixture consisting of 20 to 92 percent by weight of 20 to 92 percent by weight of CdO and 8 to 80 percent by weight of finely divided cadmium oxide and 8 to 80 percent by weight 35 percent glass frit, consisting of 10 to 60 percent by weight of a finely divided glass frit, as well as 10 to inert carrier liquid, the glass frit containing 60 percent by weight of carrier liquid, with 83.0 to 99.9 percent by weight of a base the finely divided glass frit of 89 to 96.9 Weight composition consists of 60 to 80 Percent by weight of a resin composition consists of PbO, 8 to 16 percent by weight of B ₂ O _3, and 12 to 24 percent by weight of PbO, 8 to 16 percent by weight of ZnO. The disadvantage of this weight percent B ₂ O _S and 12 to 24 weight percent resistor paste is that it contains the electrical resistance ZnO Glass coating in strong Ag ₂ O and containing 3 to 8 percent by weight Al ₂ O _3. Dimensions changed bat. 45 From the United States patent 31 54 503 it is known _{to disperse Ag 2} O, Au ₂ O and Cu ₂ O in glass frits, to improve the wetting ability of the glass frit. This patent does not teach how the electrical resistance given before coating is used The invention relates to a resistor paste, the 50 mainly composed of CdO resistor homogeneous dispersion of finely divided jester components almost unchanged after covering with glass is present in an inert carrier liquid and can be obtained for. Melt applied to a ceramic support. US Pat. No. 2,720,471 relates to is, as solid constituents 40 to 90 percent by weight of a thermistor, namely the thermistor should be protected from a mixture consisting of 20 to 92 percent by weight of ammonia, CO ₂ , Cl ₂ , etc., and finely divided cadmium oxide and 8 to 80 percent by weight to prevent the thermistor from being made of finely divided glass frit and changing its oxygen content. This weight percent contains carrier liquid, whereby according to this USA patent specification, through the finely divided glass frit from 83.0 to 99.9 percent by weight drawing of the thermistor with a glass of the system, there is a basic composition that is 60 PbO - ZnO - Al ₂ O ₃ - SiO ₂ -B ₂ O ₃ reached. Up to 80 percent by weight PbO, 8 to 16 percent by weight, it is not suggested there that a glass frit should contain _{a resistance paste ALO in percent B 2} O ₃ and 12 to 24 percent by weight ZnO _;)
contains. The invention is based on the object of a So far, many attempts have already been made to create resistive paste of the type mentioned in order to form glaze resistors by applying a 65, that with this a large area of the resistance paste can be adjusted to a ceramic insulator electrical conductivity, and melt the same. To describe the temperature coefficient (TK) should be as small as possible. ν R the USA. Patents 29 24 540 and 30 52 573 In addition, the resistor paste should be through a