JPS628404A - Insulating paste - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thick film glass paste for forming an insulating layer which can be fired at a relatively low temperature in a non-oxidizing atmosphere, particularly for the insulation of thick film multilayer circuits using base metal conductors. Insulating glass paste useful for manufacturing layers.

Prior Art One method of manufacturing multilayer circuits involves printing a thick film conductor paste as the first conductor layer on a fired ceramic substrate.
By sequentially repeating the process of printing and baking an insulating paste to separate and insulate the upper and lower conductors, and then forming a second conductor layer on top of it, the conductor layer and insulation can be created using a thick film method. There is a method of stacking layers alternately. The insulating paste used in such thick film multilayer circuits is generally a glass paste containing an oxide filler or a partially crystalline glass paste in order to strengthen the film structure.

In recent years, there has been a strong desire in the electronics industry to employ highly reliable base metal systems. Regarding thick film conductors, consideration is being given to transitioning from negative metal systems such as Ag/Pd SAu 1Ag/Pt to base metal systems such as CO and N+. Insulating pastes that can be fired in an atmosphere that does not oxidize have also been developed.

For example, the following insulating pastes that can be fired in N2 are known. Japanese Patent Application Laid-Open No. 47-9633 is
A partially crystalline glass that does not contain pb○ is disclosed,
Japanese Patent Publication No. 59-3419 also describes an insulating paste for thick film multilayers which is composed mainly of borosilicate glass and aluminum oxide, which do not contain PbO, and which is compatible with copper conductors. Japanese Patent Publication No. 59-14203 discloses a dielectric composition composed of glass and a crystalline multi-component oxide or its precursor, and JP-A-55-130009 discloses a dielectric composition composed of zinc silicate and an alkaline earth silicate. A paste whose main components are a glassy phase and a ceramic phase containing zinc oxide was published in Japanese Patent Publication No. 59-2.
Publication No. 7119 discloses an insulating paste comprising partially devitrified barium magnesium borosilicate glass and a pinhole reducing component. Furthermore, JP-A-55-38
No. 882 discloses aluminum oxide as an active ingredient, glass, and as an oxidizing agent a metal oxide that can be reduced to a low valence during calcination, such as Ce oxide, pr 60++.
, pr 02 , rare earth oxides, and the like. All of these insulating pastes need to be fired at a relatively high temperature of about 800°C to 1000°C.

By the way, base metal thick film multilayer circuits may be composed of only conductor layers and insulating layers, or may be multilayered by incorporating thick film resistors and thick film capacitors, but in the latter case, N2 Since there is no material that can be baked in the air and has excellent properties that are practically satisfactory, a ruthenium oxide-based resistance paste, which is of the air-fired type and is commonly used in conventional quantities, is used instead. However, if this resistor is refired at a high temperature of 700°C or higher in a non-oxidizing atmosphere, it will be reduced and its electrical characteristics will change.
It was extremely difficult to create multiple layers by baking with M.

If the above-mentioned insulating paste is baked at a low temperature that does not damage the resistor, the insulation will be insufficient and the adhesive strength will be poor, making it completely unusable.

JP-A No. 58-2093 discloses that the main ingredients are a ceramic filler as an active ingredient, PbO-3i02-AI203 glass, and lead oxide with an oxidation degree of 2 or more, and a temperature of 600°C or less in a non-oxidizing atmosphere. An insulating paste that is fired is disclosed. However, when the glass paste shown here is baked onto an alumina substrate, the insulation is insufficient.
It also has the disadvantage of poor water resistance.

In addition, a low-temperature firing type glass paste using CdO-rich glass is known, but it has many pores and has insufficient insulation resistance, moisture resistance, and water resistance. Insulating paste for medium and low temperature firing has not been obtained.

Problems to be Solved by the Invention It is an object of the present invention to be able to sinter in a non-oxidizing atmosphere such as N2 at a low temperature, for example, at a temperature of 650° C. or lower, and therefore not to affect the characteristics of the ruthenium oxide resistor. Moreover, the objective is to obtain an insulating paste with excellent electrical and physical properties such as insulation and mechanical strength.

Means for Solving the Problems The present inventors solved the conventional problems by examining the composition of glass, and developed a glass that can form an insulating layer with excellent properties even when fired at a low temperature of 650°C or lower. Successfully developed a paste.

That is, in the present invention, based on the weight of A0, Si 02 27-36% Al2O3 1-3% 82 03 5-15% Pbo 45-52% Ca F2 1-3% Zn0 1-3% 35-90% by weight %, B, 10 to 35% by weight of an oxide filler, and 0 to 30% by weight of a CO oxidizing agent are dispersed in an organic vehicle.

The insulating paste of the present invention uses lead aluminum borosilicate glass containing a large amount of PbO, which has a low softening point, as a glass component, and controls fluidity by blending a relatively large amount of ST02. This prevents the migration of conductive components from the conductor layer due to the sudden drop in viscosity and the resulting insulation failure.
It is also characterized in that the increase in softening point and the decrease in water resistance caused by containing a large amount of 5102 are prevented by incorporating CaFz and ZnO.

Among the constituent components of the glass, if Si 02 is less than 27%, the softening point is too low and appropriate viscosity characteristics cannot be obtained. 3
If it exceeds 6% by weight, the softening temperature becomes too high and high film strength cannot be obtained by low-temperature firing.

Al2O3 is used for the purpose of preventing devitrification and improving weather resistance. If it is less than 1% by weight, this effect will not be exhibited, and if it exceeds 3% by weight, the melting point will become high, which is not preferable.

If B2O3 is less than 5% by weight, the softening point will be too high, and if it is more than 15% by weight, the softening point will be too low.

CaF2 is used as a flux for the purpose of suppressing the rise in softening point. If it is less than 1% by weight, there is no effect, and if it is more than 3% by weight, devitrification occurs, which is not preferable.

ZnO is blended for the purpose of improving chemical durability, especially water resistance. If the blending amount is less than 1% by weight, this effect will be weak;
Exceeding this percentage by weight is not preferred because it tends to devitrify.

Glass powder accounts for 35 to 905 of the total inorganic components of the paste.
It weighs 90.

The oxide filler accounts for 10 to 10% of the total inorganic components of the paste in order to control the fluidity of the fired film and to smoothly remove carbon, which is a combustion residue of the organic vehicle, from the film during firing.
It is blended within the range of 35 wt ω%. If the weight is less than 10 weight, the film becomes glassy and easily flows during re-firing, which may cause the pattern to spread, interact with the electrode components, cause curling of the electrode, poor soldering properties, and poor insulation of the insulating layer. Problems such as these may occur, and decarbonization may also become insufficient.

If it exceeds 35% by weight, the film strength will be weak and it will become brittle, which is not preferable. As the oxide, those commonly used in this type of insulation paste, such as aluminum oxide, magnesium oxide, lanthanum oxide, and titanium oxide, can be used.

The oxidizing agent is blended to promote complete combustion of the organic vehicle and leave no carbon residue during firing in a non-oxidizing atmosphere. For example, conventionally known Pb 02 and P
I) s 04 , Ce 02 , pr 02, pr 6
on, TaO2, Co 304, Nd 203, S'0
2 etc. can be mentioned. The effect of Pb0z is particularly large.

The blending ratio is 0 to 30% by weight of the total inorganic components, and depending on the composition of the glass and firing conditions, it may not be blended at all.
It is usually desirable to use 5% by weight or more.

The blending ratio of the inorganic components is preferably glass powder 55-70.
% by weight, 15-30% by weight of oxide filler and 1% of oxidizing agent.
It is 0 to 25% by weight.

Note that it is desirable to use fine powder with a diameter of 10 A1 or less for each component.

Any organic vehicle may be used as long as it is used in ordinary thick film pastes, and resins, solvents, plasticizers, and other additives may be appropriately selected and used. As the resin component, it is particularly preferable to use a resin that can be easily completely combusted at a relatively low temperature in an atmosphere of low oxygen partial pressure, such as ethyl cellulose, ethyl oxyethyl cellulose, nitrocellulose, methacrylate resin, and butyral resin.

f1 Next, the present invention will be specifically explained with reference to Examples.

In the examples, all percentages and parts are based on weight.

Examples 1 to 5 Glass raw material powders were weighed and mixed to have the composition shown in Table 1, placed in a crucible, and heated at 188 °C at 1300 to 1450 °C in an electric furnace.
It was melted by heating for a while. The melt was poured into water, rapidly cooled, and pulverized to produce a glass powder with an average particle size of 3.

Next, this powder, Al2O3 powder and PbO2 powder with an average particle size of 0.54 were mixed in the proportions shown in Table 1, and a 20% butyl calpitol solution of ethyl cellulose was added to glass, Al2O3, Total of PbO2 100
and further added appropriate amounts of butyl calpitol and dibutyl phthalate to adjust the viscosity and kneaded them to produce insulating pastes.

Copper paste is placed as a lower conductor on a 1 inch x 1 inch 96% alumina board with a width of 0.5n at intervals of 2 mm (5 pieces).
The screen was placed in a comb-like pattern, and the
It was fired at 0°C. Print the above insulating paste on top of this,
After drying at 150° C., baking was performed in N2 at a maximum temperature of 600° C. to form an insulating layer with a thickness of 404 mm. Next, copper paste was printed on it in a similar comb-like pattern perpendicular to the lower electrode pattern, and fired in the same manner as the lower electrode to create a test sample.

The following tests were conducted on each test sample, and the results are also shown in Table 1.

■Measurement of insulation resistance: A DC voltage of 50 V was applied between the upper and lower conductors to measure insulation resistance.

■Humidity load life test: After applying a DC voltage of 50 V continuously for 100 hours in a high temperature and high humidity bath at 60° C. and 95% relative humidity, the sample was taken out and left at room temperature for 1 hour, and the insulation resistance was measured.

(Margin below) Table 1 Comparative Examples 1 to 4 Glass powder, oxide filler, and Pb having the composition shown in Table 2
Performance tests were conducted in the same manner as in the examples using an insulating paste obtained by mixing Oz powder in a predetermined ratio and uniformly dispersing it in an organic vehicle. Table 2 shows the blended colors and test results of each component.

(The following is a blank space) Table 2 Comparing Tables 1 and 2, it can be seen that the insulating pastes of the present invention are both far superior in insulation properties and moisture resistance to those shown in the comparative examples. Note that Comparative Examples 1 and 2 had low film strength and were brittle, so they were unsuitable for multilayer circuits.

Effect The insulating paste of the present invention can be used in a non-oxidizing atmosphere such as N2,
Even when fired at a low temperature of 650° C. or lower, a highly insulating continuous film without residual carbon can be formed. It also has excellent moisture resistance and water resistance, and exhibits extremely good properties as an interlayer insulating film for multilayer circuits. Therefore, it is extremely useful for forming insulating layers of thick film multilayer circuits using base metal conductors. And 6
Since it can be fired at a low temperature of 50° C. or lower, the resistance characteristics will not deteriorate even if the insulating layer is baked in a non-oxidizing atmosphere after forming the ruthenium oxide resistor.

Further, the paste of the present invention can be used not only for insulation between conductors but also for circuit protection coating and underglaze.

Claims (1)

[Claims] 1 A, 35-90% by weight of glass powder consisting of: SiO_2 27-36% Al_2O_3 1-3% B_2O_3 5-15% PbO 45-52% CaF_2 1-3% ZnO 1-% An insulating paste comprising: B. 10 to 35% by weight of an oxide filler; C. 0 to 30% by weight of an oxidizing agent dispersed in an organic vehicle. 2. The insulating paste according to claim 1, wherein the oxide filler is one or more selected from the group consisting of aluminum oxide, magnesium oxide, lanthanum oxide, and titanium oxide. 3 Oxidizing agents are PbO_2, Pb_3O_4, CeO_2
, PrO_2, Pr_6O_1_1, TeO_3, Co
The insulating paste according to claim 1 or 2, which is one or more powders selected from the group consisting of _3O_4, Nd_2O_3, and SrO_2. 4. Any one of claims 1 to 3, wherein A, glass powder is 55 to 70% by weight, B, oxide filler is 15 to 30% by weight, and C, oxidizing agent is 10 to 25% by weight. Insulating paste described in .