JPH0799788B2 - Print paste - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a printing paste such as a conductor paste, a resistor paste, a dielectric paste, and an insulating paste used for a printed circuit.

[Technical background of the invention and its problems]

As is well known, a printed circuit is formed by applying a conductor paste, a resistor paste or the like on an insulating heat-resistant substrate such as alumina by a method such as screen printing and firing it to form a desired conductor path, an insulating layer or the like. I am letting you.

Here, as these various printing pastes, pastes prepared as described below have been widely used in recent years.

That is, glass powder or a mixture of glass powder with one or more of dielectric powder, metal nitride powder, metal oxide powder, and metal powder, and an acrylic polymer such as polymethacrylate, A printing paste in which a styrene-based polymer such as polystyrene and an organic vehicle composed of at least one of these copolymers or a mixture of two or more thereof are blended according to the application.

On the other hand, in recent years, in order to manufacture printed circuits at low cost, the firing time of these printing pastes has been shortened, and the firing temperature of about 500 ° C or higher has been lowered. Technical demands are starting to emerge.

However, when the above-mentioned printing paste is used, when it is rapidly baked, the coating film surface of the paste is first hardened, and it is difficult for the decomposition and reaction gas generated inside the coating film to escape. That is, as a result, bubbles (pinholes) were generated inside the coating film, and eventually carbon was generated, so that desired characteristics could not be obtained. Moreover, even when firing at a relatively low temperature, similar problems have occurred, and it has not been possible to meet the technical demand.

Further, in the case of a printing paste that cannot be fired in an oxidizing atmosphere effective for thermal decomposition, such as a copper-based paste, the above problems tend to become more prominent as the thermal decomposition property deteriorates.

These problems are not limited to the case of rapid baking, but in general, decomposition and reaction gas easily accumulate inside the coating film.

On the other hand, printing pastes using fibrin compounds such as ethyl cellulose and methyl cellulose as an organic vehicle have been developed, but they do not satisfy the above-mentioned technical demands, and in particular, they are fired in a non-oxidizing atmosphere such as nitrogen. When it was done, a lot of carbon remained.

As described above, in the conventional printing paste, decomposition or reaction gas is likely to be accumulated in the coating film, which causes a problem that desired characteristics cannot be obtained. Furthermore, the above-mentioned printing paste has poor leveling property (flatness) after firing, and therefore, for example, when a fine printed circuit is formed, the film thickness of the coating film is not constant, so Had come to a decline in the characteristics of.

[Object of the Invention]

The present invention has been made in view of the above problems, and the first invention facilitates discharge of decomposition or reaction gas generated inside the coating film during firing by adding and mixing solid wax. As a result, a printing paste capable of preventing deterioration of coating film properties during firing is provided, and the second invention further improves the leveling property after firing by adding and blending solid wax and fluid paraffin. The purpose is to provide a printing paste.

[Outline of Invention]

The first invention is a printing paste in which at least one or a mixture of two or more of an acrylic polymer, a styrene polymer, and a copolymer thereof is used as an organic vehicle and glass powder is mixed and kneaded with the organic vehicle. Since solid wax is further added and mixed, the solid wax improves the debinding (decomposition, volatilization) action of the organic vehicle and facilitates the decomposition or discharge of the reaction gas generated inside the coating film during firing. As a result, there is provided a printing paste capable of preventing the deterioration of the characteristics of the coating film during firing, and in the second invention, in addition to the printing paste according to the first invention, liquid paraffin is added and blended, (EN) Provided is a printing paste capable of preventing deterioration of coating film properties during firing and improving the leveling property of the coating film after firing.

Example of Invention

In order to achieve the above-mentioned object, the present inventors have used a printing paste to which a solid wax having a melting point lower than that of an organic vehicle, that is, a solid ester composed of a higher fatty acid and a higher monohydric alcohol is added. I found a good thing.

That is, the printing paste of the first invention uses at least one of an acrylic polymer, a styrene polymer, and a copolymer thereof, or a mixture of two or more thereof as an organic vehicle, and glass powder A printing paste that has been blended and kneaded, characterized in that solid wax is further added and blended. When a coating film made from this printing paste is baked, decomposition or reaction gas generated inside the coating film is discharged, in other words, printing is performed. The debindering action of the paste is greatly improved, which is convenient, and as a result, the trouble that carbon remains inside the coating film is reduced, and a printed circuit with excellent characteristics can be obtained, which is convenient.

Here, the debindering action of a conventional printing paste (paste A) using an acrylic polymer as an organic vehicle and a printing paste (paste B) according to the present invention in which a solid wax is further added to the paste A and kneaded is shown in the drawings. It demonstrates using. The drawing shows the amount of degassing (decomposition gas, etc.) of the printing paste in vacuum, the horizontal axis is the firing temperature, and the vertical axis is the amount of released gas (the shape, surface area, and weight after paste application are both Same). As can be seen from the figure, the paste B shown by the solid line according to the present invention has a larger amount of released gas of the printing paste than the conventional paste A shown by the broken line, and the decomposed gas generated inside the coating film, etc. It shows the situation in which the emission is greatly improved.

As described above, according to the present invention, the reason why the debinding action of the organic vehicle is improved is considered as follows.

That is, the melting point of solid wax is usually about 40 to 120 ° C., which is lower than that of the organic vehicle. Therefore, while baking the printing paste, solid wax begins to volatilize inside or on the surface of the coating film in the low temperature region, and as a result, fine air holes are formed on the coating film surface. It is considered that, as a result, decomposed gas and the like that has been easily accumulated inside the coating film is easily discharged (debinding) to the outside.

Here, typical materials used in the printing paste according to the present invention will be described.

The organic vehicle used in the present invention is appropriately selected according to various applications. That is, typically, a polymethacryl derivative such as polymethacrylate,
Polystyrene, a polystyrol derivative such as poly-α-methylstyrene, at least one of the above polymers, and copolymers thereof, or a mixture of two or more thereof, is mixed with an organic solvent such as an α-terpineol solution. Organic vehicles dissolved therein are suitable.

Further, in the printing paste of the present invention, dielectrics, conductors, and insulating powders mixed according to various uses and purposes are appropriately selected. That is, typically, BaTiO ₃ as the dielectric powder, boron nitride powder, tantalum nitride, titanium nitride as the metal nitride powder, PdO, RuO ₂ , ZnO as the metal oxide powder, and Ag, Au as the metal powder. , Pd,
As Pt, Cu, Ni, glass powder, crystalline glass, glass powder for binder, etc. are selected, and further, a mixed powder of two or more kinds of these is also used depending on the application.

Further, the solid wax used in the present invention is a solid ester composed of a higher fatty acid and a higher monohydric alcohol as mentioned above, and typically, polyethylene glycol, polypropylene glycol, paraffin wax,
A synthetic wax or the like is suitable.

Hereinafter, the first invention will be described with reference to specific examples.

Example 1 50% by weight of polymethyacrylate was mixed with α-terpineol, which is an organic solvent, and dissolved while heating at a temperature of 80 to 90 ° C. to prepare an organic vehicle. Also, the average particle size is 5μ
84% by weight of a ZnO-based crystal glass frit having a particle size of m and a maximum particle size of 20 μm or less, 15% by weight of the above-mentioned organic vehicle, and 1% by weight of a high melting point wax. Next, this mixture was kneaded in a liquor to obtain a homogenized dielectric printing paste.

(Example 2) 50% by weight of polymethyacrylate was mixed with α-terpineol and dissolved while heating at a temperature of 80 to 90 ° C to prepare an organic vehicle. Further, 79% by weight of copper powder having an average particle size of 2 μm and a maximum particle size of 4 μm or less, 15% by weight of the above-mentioned organic vehicle, 1% by weight of high melting point wax, and 5% by weight of lead borosilicate glass as an inorganic binder. The mixture was mixed and kneaded on a triple roll to obtain a conductor printing paste.

Comparative Example 1 As a comparative example, a printing paste having the same composition as the printing paste shown in Example 1 except for the solid wax was prepared.

An organic vehicle was prepared by mixing 50% by weight of polymethyacrylate with α-terpineol and dissolving it while heating at a temperature of 80-90 ℃. The average particle size is 5 μm and the maximum particle size is 20 μm.
85% by weight of a ZnO-based crystal glass frit consisting of the following and 15% by weight of the above-mentioned organic vehicle were blended, and this mixture was kneaded in a Likai device to obtain a homogenized dielectric paste.

(Comparative Example 2) As a comparative example, a printing paste prepared by kneading an organic vehicle using a commonly used cellulose-based polymer was prepared as a comparison example.

An organic vehicle was prepared by dissolving 10% by weight of ethyl cellulose in α-terpineol. Also, the copper powder 82.5 used in Example 2 having an average particle size of 2 μm and a maximum particle size of 4 μm or less.
Wt% and 12 wt% of the above-mentioned cellulosic organic vehicle
And 5.5% by weight of lead borosilicate glass as the inorganic binder used in Example 2 were kneaded in a Likai unit to obtain a homogenized conductor printing paste.

The composition of the printing paste described in detail above is summarized in Table 1 below.

For easy understanding of the evaluation of the printing paste obtained as described above, the dielectric printing paste of Example 1 (referred to as paste 1) and the conductor printing paste of Example 2 (referred to as paste 2) were used. Combination of the derivative printing paste of Comparative Example 1 (referred to as paste 3) and the conductor printing paste of Example 2 (paste 2), and Paste 1 and Comparative Example 2
Of conductor printing paste (referred to as paste 4). That is, the test was performed using three types of samples in which each of paste 1 and paste 2, paste 3 and paste 2, and paste 1 and paste 4 was multilayer printed.

As the first sample, paste 2 was applied by screen printing on an alumina substrate, and this was baked for 40 minutes in a nitrogen atmosphere of 600 ° C. to form the first conductor layer, and this conductor layer was covered. As described above, the paste 1 is applied, and the same firing is performed to form the dielectric layer, and the second conductor layer is formed on the dielectric layer by using the paste 2 similarly to the first layer. .

Similarly, for the second sample, the paste 2 is used to form the first conductor layer on the alumina substrate, the dielectric layer is formed by the paste 3, and the paste 2 is used to form the second conductor layer. Is formed.

Similarly, for the third sample, the paste 4 is used to form the first conductor layer on the alumina substrate, the dielectric layer is formed by the paste 1, and the paste 4 is used to form the second conductor. A layer is formed.

The printability of each sample thus obtained, the conductor resistance, the adhesion between the conductor layer and the alumina substrate, the adhesion between the second conductor layer and the dielectric layer, and the formation on the dielectric layer Table 2 shows the experimental results on the solder wettability of the conductor layer and the insulation resistance of the dielectric layer.

Here, in Table 2 above, regarding printability, the state of the coating film surface of both the conductor layer and the dielectric layer, pinholes, etc.
We have evaluated the printing conditions that affect the characteristics, etc., and those that conform to the standards (specifically, those that are equivalent to or higher than the printing paste using an ethylcellulose organic vehicle that shows good printability) are good. And

The conductor resistance value is a measurement of the resistance value of the first conductor layer.

The adhesion between the first conductor layer and the alumina substrate, and the second
The adhesion between the second conductor layer and the dielectric layer was evaluated as follows.

A lead wire was soldered to the first or second conductor layer, and the lead wire was pulled vertically to examine the peeling state from the alumina substrate. Adhesion strength of 1 kg / mm ² or more was obtained. Those having it were evaluated as good, and those having less than that were evaluated as bad.

For solder wettability, Pb-Sn eutectic solder containing 2% of silver was used, soaked at 230 ° C for 3 seconds and then pulled up, and 90% or more of the coating surface of the second conductor layer became solder. What was wet was good.

Insulation resistance was measured after leaving for 1000 hours in a constant temperature / humidity atmosphere of 60 ° C and 95% RH, and then between the conductor layers of the first and second layers at room temperature.
It shows the resistance value when a voltage of DC 50V is applied.

As shown in the above experimental results, the printing paste (first sample) according to the present invention exhibits excellent characteristics such as printability, conductor resistance, adhesion with an alumina substrate, solder wettability, and insulation resistance.

On the other hand, in the second sample, the printability, the adhesion between the second conductor layer and the dielectric layer, and the insulation resistance were deteriorated. The major cause of these deterioration of characteristics is the generation of pinhole (bubble) residual carbon and the like inside the derivative layer (paste 3).

On the other hand, in the third sample, the conductor resistance value, the adhesion between the first conductor layer and the substrate, the adhesion between the second conductor layer and the dielectric layer, and the deterioration of the insulation resistance value were observed. It is considered that these are also due to the above-mentioned defects occurring in the conductor layer due to the paste 4.

That is, the organic paste is not decomposed, bubbles (pin poles) based on the reaction gas, residual carbon, etc. are not generated in the coating film formed by the printing paste shown in this embodiment, and as a result, various characteristics are lowered. It is understood that you will never come.

Further, the printing paste shown in the examples, that is, the printing paste in which the solid wax is added and kneaded has an appropriate viscosity and thixotropic (usually thixotropic property) as compared with the printing paste in which the solid wax is not added. Has been confirmed to be obtained.

That is, since the printing paste shown in this example has an appropriate viscosity, it is difficult for the screen to be peeled off cleanly from the substrate on which the screen is printed during paste application.
When applied to a large area, the problem of screen peeling is less likely to occur.

Here, the present inventors further conducted various experiments, and as the solid wax added to the printing paste had a higher melting point, the above-mentioned thixotropy was improved and workability during coating was excellent. We found that as a result, a high yield was obtained. The amount added is 0.01%
It was confirmed that sufficient thixotropy was obtained when a wax of about 3.0% by weight was contained.

If a printing paste with improved thixotropy is used,
It can be sufficiently used for large-area printed circuits and high-speed printing, which have been considered difficult in the past.

As described above, according to the first aspect of the invention, the decomposition or discharge of the reaction gas generated inside the coating film, that is, the debinding action is improved, so that a printed circuit having excellent characteristics can be obtained.

In addition, since it has an excellent binder removal action, the degree of freedom of the conditions of the firing atmosphere such as high-speed firing, low-temperature firing, etc. is widened, and many advantages are shown for industrial use.

Further, the inventors of the present invention prepared various printing pastes and evaluated them repeatedly. As a result, in addition to solid wax, by adding and mixing liquid paraffin, the leveling property (flatness) after applying the printing paste was improved. I found a tendency to improve.

That is, the printing paste of the second invention uses at least one of an acrylic polymer, a styrene polymer, and a copolymer thereof, or a mixture of two or more thereof as an organic vehicle, and blends glass powder therein. A printing paste that has been kneaded and kneaded is characterized in that solid wax and fluid paraffin are further added and blended. When a coating film made from this printing paste is fired, the binder removal effect is significantly improved and The leveling property of the coating film is improved, and as a result, a printed circuit with excellent characteristics can be obtained, which is convenient.

Typical materials used in the printing paste according to the second invention are the materials shown in the first invention.

Hereinafter, the second invention will be described with reference to specific examples.

(Example 3) In the same manner as in Example 1 above, 50% by weight of polymethyacrylate was mixed with α-terpineol and dissolved while heating at a temperature of 80 to 90 ° C to prepare an organic vehicle. In addition, 83% by weight of ZnO-based crystalline glass frits having an average particle size of 5 μm and a maximum particle size of 20 μm or less, and 15% by weight of the above organic vehicle.
And 1 wt% high melting point wax and 1 wt% fluid paraffin. Then, this mixture was kneaded in a liquor to obtain a homogenized dielectric printing paste.

Comparative Example 3 As a comparative example, a printing paste having the same composition except for the fluid paraffin, that is, the dielectric printing paste shown in Example 1 was used as a comparative example so that it can be compared with the above-mentioned Example 3.

The composition of the dielectric printing paste described in detail above is summarized in Table 3 below.

The dielectric printing paste obtained as described above was applied to each of the alumina substrates by screen printing under the same conditions, and the dielectric printing paste was baked for 40 minutes in a nitrogen 600 ° C atmosphere to form a dielectric layer. .

Here, the sample formed by the dielectric printing paste shown in Example 3 is referred to as Sample 4, and similarly the sample according to Comparative Example 3 is referred to as Sample 5 to focus on the leveling property for comparative evaluation.

The maximum surface roughness of the dielectric layer surface of sample 4 is 2 μm,
On the other hand, Sample 5 had a maximum size of 5 μm.

In addition, in addition to this, when conducting paraffin was added to a conductor printing paste and the like comparison was carried out, it was found that the one with fluidized paraffin had a smoother surface than the one without added. confirmed. Furthermore, various experiments were conducted on the amount of the fluidized paraffin added, and it was found that the smoothness was remarkably improved when 0.01% to 5.0% by weight was relatively added. Further, a printing paste in which the solid wax is not kneaded (for example, Comparative Example 1
The leveling property was evaluated by adding fluidized paraffin to the dielectric paste shown in 2.), but some improvement was observed, but the effect was not remarkable.

Furthermore, no deterioration of other properties (for example, printability, adhesion, electrical properties, etc.) due to the addition of fluid paraffin was observed, and there was no adverse effect on various properties.

As described above, according to the second invention, the solid paste and the fluid paraffin are added and kneaded, that is, according to the second invention, in addition to the effect obtained by the first invention, the leveling of the coating film after firing is performed. The property (smoothness) is improved.

Therefore, for example, even when a fine printed circuit or the like is created, the deterioration of the characteristics can be prevented, and the industrial utility is great.

In the above examples, the specific composition of the printing paste, the manufacturing method and the like are described in detail, but the present invention is not limited to this, and the effect can be achieved even by other manufacturing methods. Is also possible.

Further, the printing paste according to the present invention is not limited to be fired under the conditions and atmosphere shown in this embodiment, but may be fired under appropriate conditions and atmosphere.

〔The invention's effect〕

According to the first aspect of the present invention, since the solid wax is blended, the binder removal action of the organic vehicle at the time of firing is improved, and as a result, it is possible to provide a printing paste capable of preventing the deterioration of the characteristics of the coating film at the time of firing. According to the second invention, since the solid wax and the fluid paraffin are blended, it is possible to provide a printing paste capable of preventing the deterioration of the characteristics of the coating film during firing and improving the leveling property after firing. .

[Brief description of drawings]

The drawing is a profile showing the debindered state of the printing paste in a vacuum atmosphere.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Megumi Sakamaki, No. 1 201, Funakoshi-cho, Yokosuka-shi, Kanagawa Inside the Yokosuka Plant of Toshiba Corporation (56) Reference JP-A-49-55404 (JP, A) Sho 49-68808 (JP, A)

Claims (2)

[Claims] 1. An acrylic polymer, a styrene polymer,
And an organic vehicle containing at least one of these copolymers or a mixture of two or more thereof; a glass powder blended with the organic vehicle; and a solid wax additionally blended with the organic vehicle. A printing paste characterized by that. 2. An acrylic polymer, a styrene polymer,
And an organic vehicle containing at least one of these copolymers or a mixture of two or more thereof; a glass powder blended with the organic vehicle; a solid wax blended with the organic vehicle; an organic vehicle A printing paste comprising: a liquid paraffin added to and blended with.