JPS62119277A - Printing paste for thick film - Google Patents

Abstract

PURPOSE:To obtain the titled paste having low viscosity variation and high printing accuracy and useful for the screen printing of an electrically conductive pattern, a resist pattern, etc., by compounding metallic powder with an organic vehicle and a specific solvent such as dibutyl phthalate. CONSTITUTION:The objective paste can be produced by kneading metallic powder, metal oxide powder, dielectric substance powder, glass powder, etc., with an organic vehicle and compounding the resultant printing paste for thick film IC with dibutyl phthalate and/or diethyl phthalate which is a solvent having high boiling point and low vapor pressure at room temperature. The volume ratio of dibutyl phthalate and/or diethyl phthalate in the whole solvent is preferably >=60%.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a thick film printing paste for conductive patterns, resistance patterns, dielectric patterns, and insulation patterns formed by screen printing.

[Background of the invention]

Various thick film circuits formed by screen printing are used in a wide range of fields, and conductors, resistors, dielectrics, and insulators can be formed by using thick film printing pastes depending on the application. These printing pastes are made into a paste by kneading the main material for thick film elements, additives added as necessary, and an organic vehicle, and are printed on a substrate or circuit elements on a substrate using screen printing technology. - Selectively patterned on top of the insulating layer. The main material of the thick film element is Au.

Examples include metal powders such as Ag, Pb, Cu, and Ni, metal oxide powders such as RuO2゜PdO, dielectric powders such as BaTiO3, and glass powders such as crystallized glass, and printing pastes for thick films using these. is publicly known.

By the way, it is desirable that the viscosity of each of the thick film printing pastes described above does not change over time, and if the viscosity changes over time, an important problem arises in that printing accuracy deteriorates. This change in viscosity is mainly caused by the evaporation of the solvent in the organic vehicle, and therefore, it is desired to develop an organic vehicle whose viscosity changes as little as possible during the printing process.

[Prior art and its problems]

That is, conventional organic vehicles use, as a binder, a cellulose compound represented by ethyl cellulose, an acrylic compound such as polymethacrylate, etc. Generally, these organic vehicles were formed by dissolving them in a solvent, but the viscosity of these organic vehicles changes in a short period of time, and the viscosity increases with evaporation of the solvent, resulting in changes in film thickness during the screen printing process, etc. This resulted in a decrease in printing accuracy, and problems such as clogging of the mensch occurred at times.

This is because conventional solvents for organic vehicles, represented by α-terpineol and n-butylcarpitol acetate, have boiling points of 218°C and 217°C for the latter.
This is because the vapor pressure at room temperature is considerably high even at this level of boiling point, and evaporation occurs.

[Purpose of the invention]

Therefore, the problem to be solved by the present invention is to solve the above-mentioned drawbacks of the prior art, that is, to realize a thick film printing paste using an organic vehicle with little change in viscosity. The purpose is to provide a printing paste with excellent long-term stability and less variation in film thickness.

[Summary and operation of the invention]

As a result of various studies, the inventors of the present invention have discovered that a thick film printing product is produced by kneading one of metal powder, metal oxide powder, dielectric powder, and glass powder, or a mixture of two or more of these powders, with an organic vehicle. In the paste, as a solvent for the organic vehicle, at least one of dibutyl phthalate and diethyl phthalate, which are solvents with a high boiling point and a low vapor pressure at room temperature, is used alone, or at least one of them is used as a main component. It has been found that the above-mentioned object can be achieved by using a thick film paste 61 using the above-mentioned method.

That is, dibutyl phthalate and diethyl phthalate have higher boiling points and lower vapor pressures at room temperature than the above-mentioned α-terpineol and n-butylcarpitol acetate, and also dissolve various binders, and can be used after printing. It can be easily dried even in the drying process of

[Embodiments of the invention]

The inventors have studied various compounds that have a higher boiling point than the above-mentioned α-terpineol and n-butyl carpitol acetate and have excellent binder solubility. That is, if the boiling point is high, the vapor pressure at room temperature will be low, the evaporation rate will be slow, and it can be expected that the above-mentioned viscosity change (viscosity increase) can be suppressed. However, if the boiling point becomes extremely high and the vapor pressure at room temperature becomes too low, it becomes extremely difficult to dry the printed pattern in the post-printing drying process, which is usually carried out at 120-150°C for 10-20 minutes. . It also needs to have excellent solubility as a solvent to dissolve various binders. In particular, the inventors have developed a vehicle for Cu paste that is fired in an inert gas atmosphere such as a nitrogen atmosphere, that is, a solvent that can also dissolve a decomposable binder in an inert gas atmosphere. I also considered something. As a result of comparing and studying various solvents from these various viewpoints,
It has been found that dialkyl phthalic acid-based dibutyl phthalate and diethyl phthalate are suitable and have extremely excellent properties.

The vapor pressure temperature at a vapor pressure of 10 mmHg as the boiling point, melting point, and evaporation barometer values of dibutyl phthalate and diethyl phthalate, and the above-mentioned α-terpineol as a reference example for comparison are shown in Table 1 below. It is.

(Table-1) The above diethyl phthalate and dibutyl phthalate are
Of course, each of them can be used alone as a solvent, or a mixture of diethyl phthalate and dibutyl phthalate can be used as a solvent. Furthermore, approximately 55 wt% or more, preferably 5 Qwt% or more of the entire solvent contains one or two of diethyl phthalate and dibutyl phthalate as main components, one of them is a mixture of the two, and the other is conventional. The α-terpineol used, rl −
Butyl carpitol, n-butyl carpitol acetate, pine oil, castor oil, etc. may also be used.

As mentioned above, the binder is dissolved in a solvent containing diethyl phthalate, dibutyl phthalate alone, a mixture of the two, or at least one of the two as a product. The ratio of binder 1'' to solvent is approximately 1:9.

As a binder, cellulose-based synthetic compounds such as ethyl cellulose, methyl cellulose, and nitrocellulose, acrylic synthetic compounds such as rl-butyl methacrylate, inbutyl methacrylate, and ethyl methacrylate, or other synthetic compounds such as polystyrene, rosin, etc. Natural resins and the like can be used, and one or more of these are mixed to form a binder, and the binder is dissolved in the above-mentioned solvent to prepare an organic vehicle.

The organic vehicle thus prepared can be one of metal powder, metal oxide powder, dielectric powder and glass powder.
It is thoroughly kneaded with a seed or a mixture of two or more of these to form a thick film paste depending on the application, and formed into a desired pattern by screen printing.

(Experiment Example-1) As a binder for the organic vehicle, one or a mixture of two or more of 1-butyl methacrylate, inbutyl methacrylate, and ethyl methacrylate, which have excellent decomposition properties in an inert gas atmosphere, is used. , as a solvent Table-2
As shown in , various compounds containing at least one of diethyl phthalate and/or dibutyl phthalate were prepared, weighed, and mixed at a binder:solvent ratio of 1:9 to prepare an organic vehicle. . The binder was dissolved by heating to 80 to 90° C. and using a reduction cooler.

7.6 g of each of the above-mentioned organic vehicles was added to (U powder 50.9, 3.5 g of bismuth oxide [manufactured by Sumitomo Metal Mining ■], and 11 g of borosilicate glass frit [manufactured by Asahi Glass ■, ASF1340]) with an average particle size of 0.77 μm. :1 was added and sufficiently kneaded using a roll mill (to create U paste).

The initial viscosity of each Cu paste formed in this way was measured using a Brookfield viscometer, and 109 pieces of each Cu paste were taken and spread uniformly on the four corners of a smooth insulating substrate. 25℃, 75%R
After being left in H for 4 hours, the mixture was collected with a spatula, kneaded, etc., and its viscosity was measured using a Brookfield viscometer, and the change in viscosity was examined in comparison with the initial viscosity.

The results are shown in Table 2 below.

In Table 2, ◎ indicates the viscosity change rate is 0 to 5, ○ indicates the same 5 to 10%, Δ indicates 10 to 20, and X indicates 20%.
% or more, and the ◎ and ○ marks indicate a high evaluation in terms of viscosity change. Furthermore, as is clear from Table 2 above, α-terpineol is suitable as another solvent to be added to diethyl phthalate and dibutyl phthalate, and in this case, the amount of α-terpineol is 40 Wt1 or less relative to the entire solvent (Table 2)... ...It was confirmed that the viscosity change could be sufficiently suppressed by the presence of the solvent component and the viscosity change. In addition, in terms of drying properties, the above-mentioned ◎ and ◯ marks both showed sufficient drying properties in a drying process of 10 to 20 minutes at 120 to 150°C. In addition, since this experiment example is applied to Cu paste, when drying is carried out at the lowest possible temperature, for example 120°C, to prevent oxidation during drying, taking into account this low temperature drying property and viscosity change, the coating -2 Among these, diethyl phthalate alone is most suitable as a solvent.

(Experimental Example-2) Ethyl cellulose or n-butyl methacrylate was used as the binder, and diethyl phthalate alone, dibutyl phthalate alone, diethyl phthalate 5 were used as the solvent.
3 of a mixed solution of 0wt% and dibutyl phthalate 5Qwt%
Using seeds, mix binder and solvent at a weight ratio of 1:9,
Six types of organic vehicles were prepared using the same method as in Experimental Example-1.

Then, 359 of each of the above organic vehicles was added to crystallized glass frit (ASF-1600180, 9, manufactured by Asahi Glass Corporation, ASF-1600180, 9) with an average particle size of 2 μm, and the mixture was sufficiently kneaded in a roll mill to create 6 types of glass insulation pastes. .

The viscosity change was measured and evaluated using the same method as in Experimental Example 1, and as a result, good data with very little viscosity change was obtained. Further, there were no problems in terms of dryness.

(Experimental Example-3) Using isobutyl methacrylate as a binder, three types of solvents were prepared: diethyl phthalate alone, dibutyl phthalate alone, and a mixed solution of 50 wt% diethyl phthalate and 50 wt% dibutyl phthalate, and the weight ratio of binder and solvent was determined. Three types of organic vehicles were prepared using the same method as in Experimental Example 1 by mixing them at a ratio of 1:9.

Then, silver powder with an average particle size of 2 μm, 60.9, and an average particle size of 0
．． 15g of 1μm palladium powder, 4.5g of bismuth oxide
I, borosilicate lead glass frit [manufactured by Asahi Glass, AS
48 F of each of the above organic vehicles was added to 5.5 g of [F-1370] and sufficiently kneaded to prepare three types of Ag-Pd pastes.

As a result of evaluating this using the same method as in Experimental Example-1, it was confirmed that the viscosity change was extremely small in all, and the drying property was also guaranteed.

(Experiment example-4) Using n-butyl methacrylate as a binder,
The same three types of solvents used in Experimental Examples 2 and 3 were prepared, and three types of organic vehicles were created using the same mixing ratio and the same method.

And ruthenium oxide with an average particle size () of 5 μm 46.
5 # and lead borosilicate glass flint [manufactured by Asahi Glass, A
48 g of the above organic vehicle was added to the mixture of SF-1380153, 5, and 9 and thoroughly kneaded to form three types of RuO2.
A system resistance paste was created.

When this was evaluated using the same method as in Experimental Example 1, all showed good results with little change in viscosity.

It was also confirmed that there were no problems with drying.

(Experimental Example-5) Ethyl methacrylate was used as the binder, and the same three solvents as used in Experimental Examples 2 and 3.4 were prepared.
Three types of organic vehicles were created using the same mixing ratio and method.

Barium titanate powder 93.5mm with an average particle size of 1.5/Jm and bismuthate glass frit 6.5mm with an average particle size of 11zm. ! To the mixture of 7, 58g of each of the above organic vehicles was added and thoroughly kneaded, and three types of BaTiO3 were added.
A dielectric paste of the system was created.

When this was evaluated using the same method as in Experimental Example 1, it was confirmed that all the samples showed good results with little change in viscosity, and there were no problems in terms of drying properties.

In addition, in the above-mentioned experimental example, the viscosity change was evaluated immediately after 4 hours, but some of the experimental examples 1 also showed that the viscosity change was almost the same even after being left for 30 hours. This was confirmed in an experiment where the paste was left for 30 hours. It goes without saying that the present invention can also be applied to binders other than those described above and to pastes other than the experimental examples.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a paste for thick film with little change in viscosity during the printing process, and a paste with high printing accuracy that has little variation in film thickness even after continuous printing for a long time. The realization of a highly reliable paste that is stable over time has great industrial value.

that's all

Claims (1)

[Claims] In a thick film printing paste prepared by kneading one or a mixture of two or more of metal powder, metal oxide powder, derivative powder, and glass powder with an organic vehicle, as a solvent for the organic vehicle, the boiling point dibutyl phthalate, a solvent with high vapor pressure and low vapor pressure at room temperature;
A thick film printing paste characterized by using at least one diethyl phthalate alone or containing at least one diethyl phthalate as a main component.