JPH056281B2 - - Google Patents

Description

[Detailed description of the invention]

Industrial Application Field The present invention is a thick film glass paste for forming an insulating layer that can be fired at a relatively low temperature in a non-oxidizing atmosphere, and is particularly useful for producing an insulating layer of a thick film multilayer circuit using a base metal conductor. related to insulating glass paste. BACKGROUND OF THE INVENTION One method of manufacturing multilayer circuits is to print and bake a thick film conductor paste as a first conductor layer on a fired ceramic substrate, and then print an insulating paste to separate and insulate the upper and lower conductors. There is a method in which conductor layers and insulating layers are alternately laminated in a thick film method by sequentially repeating the steps of firing and forming a second conductor layer thereon. As an insulating paste used in such thick film multilayer circuits, a glass paste containing an oxide filler or a partially crystalline glass paste is generally used 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, Ag/Pd, Au,
The transition from noble metals such as Ag/Pt to base metals such as Cu and Ni is being considered, but along with this, there is a need for new materials that are compatible with these base metal conductors and are fired in an atmosphere that does not oxidize the base metals such as _N2 . An insulating paste that can be used has also been developed. For example, the following insulating pastes that can be fired in _N2 are known. JP-A No. 47-9633 discloses a partially crystalline glass that does not contain PbO, and JP-A No. 59-3419 also discloses a partially crystalline glass that does not contain PbO.
An insulating paste for thick film multilayers, which is based on PbO-free borosilicate glass and aluminum oxide and is compatible with copper conductors, is described. Tokuko Showa 59-14203
The publication discloses a dielectric composition consisting of glass and a crystalline multicomponent oxide or its precursor, disclosed in Japanese Patent Application Laid-Open No. 1982-
Publication No. 130009 describes a paste whose main components are a vitreous phase consisting of zinc silicate and alkaline earth silicate and a ceramic phase containing zinc oxide.
The publication discloses an insulating paste consisting of partially devitrified barium magnesium borosilicate glass and a pinhole reducing component. In addition, Tokukai Akira
No. 55-38882 discloses aluminum oxide and glass as active ingredients, and metal oxides that can be reduced to low valence during firing as oxidizing agents, such as Ce oxide, Pr ₆ O ₁₁ , PrO ₂ , rare earth oxides. An insulating paste composed of, etc. is shown. 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.
In the latter case, there is no resistance material that can be fired in _N2 and has excellent properties that are practically satisfactory, so ruthenium oxide-based resistance paste, which is the most commonly used type of air-fired type, has been used. is substituted. However, if this resistor is re-fired at a high temperature of 700°C or higher in a non-oxidizing atmosphere, it will be reduced and its electrical properties will change, so conductive paste or insulating paste should be applied after baking the resistor.
It was extremely difficult to create multiple layers by baking at high temperatures in N ₂ . If the above-described insulating paste is baked at a low temperature that does not damage the resistor, the insulating properties 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 ceramic filler as an active ingredient, PbO-SiO ₂ -Al ₂ O ₃ glass and lead oxide with an oxidation degree of 2 or more, and are heated at 600°C in a non-oxidizing atmosphere. An insulating paste is disclosed that is fired at the following temperatures: However, when the glass paste shown here is baked onto an alumina substrate,
It has the drawbacks of insufficient insulation and 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. ₂
Insulating paste for medium and low temperature firing has not been obtained. Problems to be Solved by the Invention The object of the invention is to be able to sinter in a non-oxidizing atmosphere such as N ₂ at a low temperature, e.g. below 650°C, and therefore not affect the properties of the ruthenium oxide resistor. The purpose of the present invention 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 formed an insulating layer that has excellent properties even when fired at a low temperature of 650°C or less. succeeded in developing a glass paste. That is, the present invention consists of: A. On a weight basis, SiO ₂ 27-36% Al ₂ O ₃ 1-3% B ₂ O ₃ 5-15% PbO 45-52% CaF ₂ 1-3% ZnO 1-3% 35-90% by weight of glass powder; B. 10-35% by weight of oxide filler; C. 0-30% by weight of oxidizing agent.
This is an insulating paste made by dispersing the above in an organic vehicle. Function 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 SiO ₂ . Contains CaF ₂ and ZnO to prevent the migration of conductive components from the conductor layer due to a sudden drop in viscosity and the resulting insulation failure, and to prevent the increase in softening point and decrease in water resistance caused by containing a large amount of SiO ₂ . It is characterized by the fact that it was prevented by doing this. Among the constituent components of glass, if SiO ₂ is less than 27% by weight, the softening point is too low and appropriate viscosity characteristics cannot be obtained. When it exceeds 36% by weight, the softening temperature becomes too high and high film strength cannot be obtained by low-temperature firing. Al ₂ O ₃ is used for the purpose of preventing devitrification and improving weather resistance. This effect is not limited if it is less than 1% by weight,
If it exceeds 3% by weight, the melting point will become high, which is not preferable. If B ₂ O ₃ 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. CaF ₂ is used as a flux to suppress 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 added to improve chemical durability, especially water resistance. If the amount is less than 1% by weight, this effect is weak, and if it exceeds 3% by weight, devitrification tends to occur, which is not preferable. Glass powder accounts for 35 to 90% of the total mineral content of the paste.
Use % by weight. The oxide filler is mixed in a range of 10 to 35% by weight 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. .
If it is less than 10% by weight, the film becomes glassy and tends to flow during re-firing, causing the pattern to spread, interacting with the electrode components, causing curling of the electrode, poor solderability, and the insulation of the insulating layer. Problems such as defects may occur, and decarbonization may also become insufficient. 35
If it exceeds % 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, such as conventionally known PbO ₂ , Pb ₃ O ₄ , CeO ₂ , _PrO2 , _{Pr6O11 ,}
Examples include TeO ₃ , Co ₃ O ₄ , Nd ₂ O ₃ and SrO ₂ .
The effect of PbO ₂ is particularly large. The blending ratio is 0 to 30% by weight based on the total inorganic components, and depending on the glass composition and firing conditions, it may not be blended at all, but it is usually 5% by weight.
It is desirable to use % by weight or more. The blending ratio of inorganic components is preferably glass powder 55
~70% by weight, 15-30% by weight oxide filler, and 10-25% by weight oxidizing agent. Note that it is desirable to use fine powder with a diameter of 10 μm 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. In particular, resin components include ethyl cellulose, ethyl hydroxyethyl cellulose, nitrocellulose, methacrylate resin, butyral resin, etc.
It is preferable to use a material that can easily burn completely at a relatively low temperature in an atmosphere with a low oxygen partial pressure. EXAMPLES 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 powder was weighed to have the composition shown in Table 1,
The mixture was placed in a crucible, and heated and melted at 1300 to 1450°C for 1 hour in an electric furnace. The melt was poured into water, rapidly cooled, and pulverized to produce glass powder with an average particle size of 3 μm. Next, this powder was mixed with Al ₂ O ₃ powder and PbO ₂ powder with an average particle size of 0.5 μm in the proportions shown in Table 1, and a 20% butyl carbitol solution of ethyl cellulose was added to glass and Al ₂ O ₃ as an organic vehicle. , PbO ₂ were added in an amount of 10 parts to a total of 100 parts, and appropriate amounts of butyl carbitol and dibutyl phthalate were added to adjust the viscosity and kneaded to produce insulation bases. On a 1 inch x 1 inch 96% alumina substrate,
Use copper paste as the lower conductor with a width of 05 mm and a spacing of 2 mm.
A five-comb pattern was screen printed and fired at 600 °C in a _N2 atmosphere. Print the above insulating paste on top of this, dry it at 150℃, and then heat it to the highest temperature in _N2 .
Firing was performed at 600°C to form an insulating layer with a thickness of 40 μm. 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 50V was applied between the upper and lower conductors to measure insulation resistance. Humidity load life test: A DC voltage of 50V was continuously applied for 100 hours in a high temperature and high humidity chamber at 60°C and relative humidity of 95%, and then the sample was taken out and left at room temperature for 1 hour to measure insulation resistance.

[Table] Comparative Examples _1-4 Examples Performance tests were conducted in the same manner. Table 2 shows the blending amount of each component and the test results.

【table】

[Table] 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. Effects The insulating paste of the present invention can form a highly insulating continuous film without residual carbon even when fired at a low temperature of 650° C. or lower in a non-oxidizing atmosphere such as N ₂ . 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. Moreover, since it can be fired at a low temperature of 650° 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: SiO ₂ 27-36% Al ₂ O ₃ 1-3% B ₂ O ₃ 5-15% PbO 45-52% CaF ₂ 1-3% ZnO 1-3% An insulating paste comprising: 35-90% by weight of a glass powder, B: 10-35% by weight of an oxide filler, and C: 0-30% 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 The oxidizing agent is PbO ₂ , Pb ₃ O ₄ , CeO ₂ , PrO ₂ ,
The powder according to claim 1 or 2, which is one or more powders selected from the group consisting of Pr ₆ O ₁₁ , TeO ₃ , Co ₃ O ₄ , Nd ₂ O ₃ , and SrO ₂ . insulation paste. 4 A. 55-70% by weight of glass powder, B. 15-30% by weight of oxide filler, C. 10-25% by weight of oxidizing agent.
An insulating paste according to any one of claims 1 to 3.