JP2769598B2 - Conductor paste - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductive paste, and more particularly, to a positive type photoresist on a ceramic wiring board for mounting semiconductor LSIs and chip parts and interconnecting them. The present invention relates to a conductive paste effective for forming a wiring pattern using a layer.

[0002]

2. Description of the Related Art In recent years, electronic devices have been increasingly miniaturized and densified, and electronic components mounted on these devices have been rapidly becoming more narrow-pitch, multi-pin, and multi-chip. Accordingly, the bonding method of LSI and IC chip has been changed from the conventional wire bonding method to a TAB (Tape Automated Bonding) method and a flip chip method suitable for multi-chip and high-density mounting. With the increase in the density of such electronic devices, a technique for forming a conductor layer pattern such as a fine wiring having a line width of 100 μm or less or a bump having a diameter of 100 μm or less on a ceramic wiring substrate has been required. Research on conductor layer materials used in such techniques has been advanced.

[0005] Conventionally, a method of forming a wiring pattern on a ceramic substrate is roughly classified into a thin film method, a plating method, a thick film method, and the like.

[0004] The thin-film method involves vapor deposition on a ceramic substrate,
It is a method of forming a conductive metal layer with a thickness of several μm order by sputtering or ion plating.In this method, although a photolithography method using a photoresist can be used, a highly accurate fine wiring can be formed. There are problems such as low adhesion between the formed wiring and the substrate, the number of steps is larger than other methods, and the thin film forming apparatus is expensive.

The plating method is a method of forming conductor wiring on a ceramic substrate by an electrochemical method in a solution, but has almost the same problems as the above-mentioned thin film method.

Further, in the thick film method, a conductor paste in which conductor particles are dispersed in an organic vehicle containing a liquid component of a solvent is used, and the conductor paste is printed on a ceramic substrate through a mesh screen and then fired. This is a method of forming a wiring pattern on a ceramic substrate. When a wiring pattern is formed by applying the thick film method, the substrate does not necessarily need to use a sintered body, and after forming a conductive paste pattern on a green sheet, firing the green sheet and applying the conductive paste Baking may be performed simultaneously, and this thick film method has an excellent feature that a conductor layer pattern having sufficient adhesion strength to a ceramic substrate can be formed at low cost.
In addition, when this method is applied to the above-described method for forming a wiring pattern using a green sheet, the liquid component in the printed conductor paste is well absorbed in the green sheet in a short time, so that the width and width of the wiring are reduced. Distance between wires is 1
A fine wiring pattern of 50 μm or less can be formed. However, when this method is applied to a method for forming a wiring pattern using a sintered body, since the liquid component is not absorbed into the sintered body, the liquid component in the printed conductor paste spreads in a horizontal direction, so-called. "Bleeding" or "Wandering" phenomenon occurs, and the width of wiring and the distance between wiring are 15
There is a problem that a conductor layer pattern of 0 μm or less cannot be formed as designed.

Therefore, in recent years, a photolithography method using a photoresist, which is a feature of the thin film method, has been introduced to form a pattern, and a method using a conductive paste, which is a feature of the thick film method, has been used to form the wiring itself. Attempted. In this method, first, after forming a photoresist layer on the surface of a glass substrate or a ceramic substrate, an interconnect is formed by transferring a wiring pattern to the photoresist layer by photolithography, and a conductive paste is rubbed into the opening. In this method, the photoresist layer is decomposed and disappeared and the conductive component is baked on a substrate at the same time by firing and baking (Japanese Patent Application Laid-Open Nos. 4-223391 and 4-223392. Kaihei 4-22
3393, JP-A-2-240996, etc.),
A fine pattern equivalent to the thin film method can be formed.

[0008] The conventional conductor paste used in such a method is a paste mainly comprising a conductor material, a resin and a solvent, such as terpineol, dibutyl carbitol, dibutyl phthalate, butyl carbitol acetate, texanol, and the like. 2,2,4-trimethylpentadiol 1,3-monoisobutyrate and the like are used. These solvents have high dissolving power of the resin.
It is a polar solvent composed of three elements, hydrogen and oxygen.

[0009]

Usually, in the conventional photolithography technique and the method of forming a wiring pattern using a conductive paste, the removal of the photoresist layer is performed by firing in an oxidizing atmosphere. The oxidizable base metal Cu, Mo-
Use of Mn or the like has a disadvantage that the conductor is oxidized. For this reason, it is necessary to use a noble metal which is hard to be oxidized, such as Au, Ag, and Pt, but this increases the cost. However, when a positive photoresist is used for the photoresist layer (JP-A-2-240996),
Since the removal of the positive photoresist layer is performed by a wet process, inexpensive metals such as Cu and Mo—Mn can be used as the conductor, and the cost is reduced. In that case, the conductor is fired in a non-oxidizing atmosphere.

However, in the conventional conductive paste, the polarity of the solvent is high, and when such a highly polar solvent is filled into the opening of the positive photoresist layer, the solvent dissolves the positive photoresist layer. There has been a problem that the pattern shape of the positive photoresist layer changes. In addition, when the excess conductive paste adheres to the positive photoresist layer, the solvent melts and integrates the positive photoresist layer, so that it is difficult to remove the excess conductive paste. . If the conductive paste remains on the surface, it is difficult to completely remove the positive photoresist layer with a developing solution, and there is a problem that a short circuit occurs in the fired wiring pattern. Therefore, there is a problem that a sharp wiring pattern cannot be formed at low cost.

The present invention has been made in view of the above problems, and forms a pattern of a positive photoresist layer on a ceramic substrate by using a photolithography technique, and forms a wiring pattern by using a conductive paste. It is an object of the present invention to provide a conductive paste capable of forming a fine wiring pattern with high accuracy at low cost.

[0012]

In order to achieve the above object, a conductive paste according to the present invention comprises a conductive paste filled in an opening of a positive type photoresist layer formed on a ceramic substrate, wherein a solvent is carbonized. It is characterized by comprising at least one hydrogen-based solvent (1).

The conductor paste according to the present invention is characterized in that in the conductor paste (1), the hydrocarbon solvent has a boiling point of 200 ° C. to 350 ° C. (2).

[0014]

The terpineol, dibutyl carbitol, dibutyl phthalate, butyl carbitol acetate, texanol,
Solvents such as 2,2,4-trimethylpentadiol 1,3-monoisobutyrate include cellulose resins and acrylics.
High dissolving ability of methacrylic resin. However, such solvents consist of carbon, hydrogen and oxygen, and because of their high polarity,
The positive photoresist is dissolved, or the conductive paste is fused to the positive photoresist to be integrated.

As a result of intensive studies, the present inventors have found a solvent that dissolves the resin used for the conductor paste but does not dissolve the positive photoresist. Such solvents are
Toluene, xylene, camphor oil, turpentine oil, pine oil, phenylcyclohexane, composed of carbon and hydrogen,
Hydrocarbon solvents such as bicyclohexyl, dodecylbenzene, pentylbenzene, dipentylbenzene, tetralin and dodecane. These solvents are low-polarity solvents having a low dielectric constant, and do not easily dissolve the positive photoresist. However, since the resin for the conductive paste is a relatively low-polarity resin and is soluble in a low-polarity solvent, the resin used for the conductive paste is dissolved.

Furthermore, among the above-mentioned hydrocarbon solvents, those having a boiling point in the range of 200 ° C. to 350 ° C. have been found to be easy to handle. That is, the boiling point is 200
When a hydrocarbon-based solvent having a temperature of not more than ° C is used, the hydrocarbon-based solvent evaporates quickly during handling of the conductive paste, and the viscosity increases and the drying speed is undesirably increased. In addition, when a hydrocarbon solvent having a boiling point of 350 ° C. or more is used, it is difficult to dry the conductor paste after filling the openings in the positive photoresist layer, and the conductor paste is easily fixed to the substrate side. Cannot be performed, which is not preferable. As materials that facilitate the handling of the conductor paste, phenylcyclohexane,
Bicyclohexyl, dodecylbenzene, pentylbenzene, dipentylbenzene, tetralin, dodecane and the like can be mentioned.

According to the conductor paste (1) having the above structure,
Since the solvent consists of one or more hydrocarbon solvents, such a conductive paste was used in a method of forming a pattern of a positive photoresist layer on a ceramic substrate and forming a wiring pattern using the conductive paste. In this case, the solvent of the conductive paste filled in the opening of the positive photoresist layer does not dissolve the positive photoresist layer and does not deform the pattern shape of the positive photoresist layer. Further, even if the excess conductive paste adheres to the positive photoresist layer, the conductive paste does not fuse and integrate with the positive photoresist layer, and the excess conductive paste is removed. Becomes easier. Therefore, the positive photoresist layer can be completely removed by the developer, and no short circuit occurs between the baked wires. Therefore, it is possible to form a fine wiring pattern with high accuracy.

Further, the conductor paste (2) having the above configuration
According to this, in the conductive paste (1), since the hydrocarbon solvent has a boiling point of 200 ° C. to 350 ° C., drying of the conductive paste is not too early or too late, and the conductive paste is appropriately dried. It becomes easy to maintain the viscosity for a long time, and it becomes easy to handle.

[0019]

EXAMPLES AND COMPARATIVE EXAMPLES Hereinafter, examples and comparative examples of the conductor paste according to the present invention are described by forming a pattern of a positive type photoresist layer on a ceramic substrate by using a photolithography technique, and forming a wiring by using the conductor paste. The case of using the method for forming a pattern will be described as an example with reference to the drawings. [Example 1] The conductor paste according to Example 1 was 90 parts by weight of a conductor raw material powder consisting of 75 parts by weight of molybdenum powder, 15 parts by weight of manganese powder, 5 parts by weight of titanium oxide, and 5 parts by weight of silica. 4 parts by weight of phenylcyclohexane as a hydrocarbon solvent, isobutyl methacrylic resin 6
It was made by adding parts by weight.

In order to form a wiring pattern by the above-described method using such a conductive paste, first, a liquid positive resist (AZ4903 manufactured by Hoechst Japan) is applied to the entire surface of the ceramic substrate 11 made of alumina sintered body. It was applied by a coater method. Thereafter, the film was dried in an oven maintained at 90 ° C. for 30 minutes and prebaked to form a solid positive photoresist layer 12 having a thickness of 25 μm (FIG. 1A). As the ceramic substrate 11, a known ceramic substrate made of mullite, glass ceramic, aluminum nitride, or the like can be used in addition to alumina. In addition, as a liquid positive photoresist, in addition to AZ4903 manufactured by Hoechst Japan,
AZ4620 / A manufactured by the company can be used, and the liquid positive type photoresist is not only a bar coater method but also a roll coater method, a dip method and a Wheeler method (spinner method).
Can be deposited. However, if the thickness is 10
It is preferable to set the thickness within the range of from 50 μm to 50 μm, and a roll coater method or a bar coater method is suitable for uniformly forming the positive photoresist layer 12 having a thickness in this range on the ceramic substrate 11. If the thickness is out of the above range, it is difficult to fill the conductive paste 16 in a later step.

Next, an ultraviolet ray 14 having an exposure amount of 700 mJ / cm ² is applied to the positive photoresist layer 12 through a photomask 13 having a wiring pattern of a predetermined shape with a wiring rule of 50 μm in line width and 40 μm in distance between lines. Exposure was performed (FIG. 1B). The appropriate exposure is 700 to 8
00 mJ / cm ² and the exposure amount is 700 mJ / cm ²
Hereinafter, in the subsequent step (FIG. 1C), the opening 1 is developed.
5 cannot be completely opened and 800 mJ / c
If m ² or more, overexposure occurs and the cross-sectional shape of the opening 15 becomes an inverted trapezoid, which is not preferable.

Next, a developer (Hoechst Japan 400
(K: water = 1: 4), the ceramic substrate 11 having the positive photoresist layer 12 is immersed and shaken to perform development processing, and the opening 15 corresponding to the wiring pattern is formed in the positive photoresist layer 12. (FIG. 1)
(C)). In addition to the immersion rocking method,
A spray method or the like can be used. The opening 15
In the case where a photoresist having an image defect remains, the photoresist can be removed by dry etching such as plasma ashing.

Next, the ceramic substrate 11 is dried in an oven maintained at a temperature of 90 ° C. for 40 minutes and prebaked, and then the positive type photoresist layer 12 is developed in a later step (FIG. 1F). In order to enable removal by a liquid, the positive photoresist layer 12 having an opening 15 formed therein is formed.
The entire surface was exposed using ultraviolet light 14 having an exposure amount of 700 mJ / cm ² (FIG. 1D). The appropriate exposure is 7
It is 00 to 800 mJ / cm ² . Further, this overall exposure step may be performed after the conductor paste filling step (FIG. 1E) or may be performed after the conductor paste is dried in the step shown in FIG. 1F.

Next, the conductive paste 16 was filled into the opening 15 of the positive photoresist layer 12 by rubbing it with, for example, a Teflon spatula 18 (FIG. 1E). If the conductive paste 16 remains on the positive photoresist layer 12 except for the openings 15, the conductive paste 16
It may be scraped off with a Teflon spatula 18 or the like to which no is adhered.

Next, the conductive paste 16 filled in the opening 15 is dried for 10 minutes in an oven maintained at a temperature of 90 ° C., and the conductive raw material powder is adhered to the ceramic substrate 11 by the resin in the conductive paste 16. . Thereafter, the surface of the positive photoresist layer 12 is polished for 10 seconds using a lapping film (abrasive alumina 1 μm) to remove excess conductive paste 16. Next, the filling direction is changed by 90 degrees from the direction at the time of the first filling, and the conductive paste 16 is filled again, and then dried and polished. Filling was performed so that no excess paste remained in portions other than the portion 15. After this, the ceramic substrate 1
1 in a developer (Hoechst Japan 400K: water = 1: 1)
4) A developing process is performed by immersing the substrate in the container and oscillating to dissolve and eliminate the positive photoresist layer 12 to remove the same, thereby forming a conductor pattern made of only a dried conductor paste 16 on the ceramic substrate 11. (Fig. 1
(F)).

Finally, by baking at 1500 ° C. in a mixed gas atmosphere of nitrogen and hydrogen containing trace water vapor, organic substances in the conductor paste 16 are decomposed and eliminated, and the conductor is baked on the ceramic substrate 11. Then, a wiring pattern 19 was formed (FIG. 1G).

When the accuracy of the finally formed wiring pattern 19 was examined with a scanning electron microscope, the line width was 50 μm.
The accuracy was extremely high at ± 2 μm. When an optical microscope was used to determine whether or not the wiring was short-circuited, there was no short-circuit between the wirings. The boiling point of phenylcyclohexane used as the solvent of the conductor paste 16 was about 240 ° C., and the handling was easy.

The preferable composition range of the conductor paste 16 is 84 to 96 wt% of the conductor material and 2 to 6 wt% of the resin.
%, The solvent is 2 to 10% by weight, and the conductive paste 16 can be prepared by a known method such as a three-roll mill.

In this embodiment, the conductive paste 1
The case where only one kind of hydrocarbon solvent, phenylcyclohexane, was used as the solvent of No. 6 was described as an example.
6, the resin used for dissolving, but the positive photoresist does not dissolve, toluene, xylene, camphor oil, turpentine oil, pine oil, bicyclohexyl, dodecylbenzene, pentylbenzene, dipentylbenzene,
Tetralin, dodecane, or the like may be used, or a combination of one or more of these may be used. In addition, when those having a boiling point in the range of 200 to 350 ° C. are used, handling becomes easy.

Further, in the present embodiment, the case where isobutyl methacrylic resin is used as the resin has been described as an example. However, a developing solution (water-based) used in the subsequent developing process of the positive type photoresist layer 12 is described. A water-insoluble resin that does not dissolve in water, that is, ethyl cellulose, acrylic, methacrylic resin, or the like may be used.

In this embodiment, Mo is used as the conductor.
-Mn was used as an example, but other C
u, Au, Ag, Pd, or the like may be used, and when Mo—Mn or Cu is used, the cost can be reduced. Further, about 1 to 10 parts by weight of an inorganic powder such as glass SiO ₂ or TiO ₂ may be added to 100 parts by weight of the conductor raw material powder in order to enhance the adhesion between the fired conductor and the ceramic substrate. [Example 2] The conductor paste according to Example 2 was produced in the same manner as in Example 1 except that bicyclohexyl was used as a solvent. Using this conductor paste, a Mo wiring pattern was formed on an alumina sintered substrate by the process shown in FIG. 1 and the wiring accuracy and short-circuit were investigated in the same manner as in Example 1. The line width was 50 μm ± 2 μm. The accuracy was extremely high, and there was no short circuit between wires. Further, since the boiling point of bicyclohexyl was about 220 ° C., the handling of the conductor paste was easy.

Example 3 A conductor paste according to Example 3 was produced in the same manner as in Example 1 except that dodecylbenzene was used as a solvent.
Using this conductor paste, a Mo wiring pattern was formed on an alumina sintered substrate by the process shown in FIG. 1 and the wiring accuracy and short-circuit were investigated in the same manner as in Example 1. The line width was 50 μm ± 2 μm. The accuracy was extremely high, and there was no short circuit between wires. Further, since the boiling point of dodecylbenzene is about 331 ° C., handling of the conductor paste was easy.

Example 4 The conductive paste according to Example 4 was a firing paste produced in the same manner as in Example 1 except that pentylbenzene was used as the solvent.
Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. 1 and the wiring accuracy and short-circuit were examined in the same manner as in Example 1, and the line width was 50 μm ± 2 μm. The accuracy was extremely high, and there was no short circuit between wires. Since the boiling point of pentylbenzene was about 205 ° C., the handling of the conductor paste was easy.

Example 5 A conductor paste according to Example 5 was produced in the same manner as in Example 1 except that dipentylbenzene was used as a solvent. Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. 1 and the wiring accuracy and short-circuit were examined in the same manner as in Example 1, and the line width was 50 μm ± 2 μm. The accuracy was extremely high, and there was no short circuit between wires. Further, since the boiling point of dipentylbenzene is about 260 ° C., the handling of the conductor paste was easy.

Example 6 The conductor paste according to Example 6 was produced in the same manner as in Example 1 except that tetralin was used as the solvent. Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. 1 and the wiring accuracy and short-circuit were examined in the same manner as in Example 1, and the line width was 50 μm ± 2 μm. The accuracy was extremely high, and there was no short circuit between wires. Further, since the boiling point of tetralin is about 207 ° C., handling of the conductor paste was easy.

Example 7 The conductor paste according to Example 7 was produced in the same manner as in Example 1 except that dodecane was used as the solvent. Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. 1 and the wiring accuracy and short-circuit were examined in the same manner as in Example 1, and the line width was 50 μm ± 2 μm. The accuracy was extremely high, and there was no short circuit between wires. Further, since the boiling point of dodecane is about 216 ° C., handling of the conductor paste was easy.

Example 8 The conductor paste according to Example 8 was a conductor paste produced in the same manner as in Example 1 except that a solvent consisting of phenylcyclohexane: bicyclohexyl = 1: 1 was used as a solvent. is there. Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. 1 and the wiring accuracy and short-circuit were examined in the same manner as in Example 1, and the line width was 50 μm ± 2 μm. The accuracy was extremely high, and there was no short circuit between wires. Further, handling of the conductor paste was easy.

Example 9 The conductor paste according to Example 9 was a conductor paste produced in the same manner as in Example 1 except that a solvent consisting of phenylcyclohexane: dodecylbenzene = 1: 1 was used as a solvent. is there. Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. 1 and the wiring accuracy and short-circuit were examined in the same manner as in Example 1, and the line width was 50 μm ± 2 μm. The accuracy was extremely high, and there was no short circuit between wires. Further, handling of the conductor paste was easy.

Example 10 The conductor paste according to Example 10 was the same as Example 1 except that toluene was used as the solvent.
This is a conductor paste manufactured in the same manner as in the case of (1). Using this conductive paste, a wiring pattern was formed on an alumina sintered substrate by the process shown in FIG. 1, and then the accuracy and short-circuit of the wiring were examined.
The accuracy was extremely high, and there was no short circuit between wires.

Example 11 The conductive paste according to Example 11 was the same as Example 1 except that xylene was used as the solvent.
This is a conductor paste manufactured in the same manner as in the case of (1). Using this conductive paste, a wiring pattern was formed on an alumina sintered substrate by the process shown in FIG. 1, and then the accuracy and short-circuit of the wiring were examined.
The accuracy was extremely high, and there was no short circuit between wires.

Example 12 The conductor paste according to Example 12 was produced in the same manner as in Example 1 except that camphor oil was used as a solvent.
Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. 1, and then the accuracy and short-circuit of the wiring were examined.
The accuracy was as high as μm, and there was no short circuit between wires.

Example 13 The conductor paste according to Example 13 was produced in the same manner as in Example 1 except that turpentine oil was used as the solvent. Using this conductive paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. 1 and then the wiring accuracy and short-circuit were examined.
m and extremely high accuracy, and there was no short circuit between wirings.

Example 14 The conductor paste according to Example 14 was the same as Example 1 except that pine oil was used as the solvent.
This is a conductor paste manufactured in the same manner as in the case of (1). Using this conductive paste, a wiring pattern was formed on an alumina sintered substrate by the process shown in FIG. 1, and then the accuracy and short-circuit of the wiring were examined.
The accuracy was extremely high, and there was no short circuit between wires.

Comparative Example 1 The conductive paste according to Comparative Example 1 was manufactured in the same manner as in Example 1 except that terpineol was used as the solvent. Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. However, in this case, the excess paste could not be removed by polishing or the like, and the accuracy and short-circuit of the finally obtained wiring were examined in the same manner as in Example 1, and the line width was 50 μm ± 20 μm.
And the accuracy was extremely low, and a short circuit occurred between some wirings.

Comparative Example 2 A conductive paste according to Comparative Example 2 was prepared in the same manner as in Example 1 except that a solvent consisting of terpineol: dibutyl carbitol = 1: 1 was used as a solvent. is there. Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. However, in this case, the surplus paste could not be removed by polishing or the like, and the accuracy and short-circuit of the finally obtained wiring were investigated in the same manner as in Example 1. As a result, the accuracy was extremely high, with a line width of 50 μm ± 20 μm. Low, and short circuit occurred between some wirings.

Comparative Example 3 The conductor paste according to Comparative Example 3 was prepared by using terpineol: dibutyl phthalate =
This is a conductor paste produced in the same manner as in Example 1 except that a solvent consisting of 3: 1 was used. Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. However, in this case, the surplus paste could not be removed by polishing or the like, and the accuracy and short-circuit of the finally obtained wiring were investigated in the same manner as in Example 1. As a result, the accuracy was extremely high, with a line width of 50 μm ± 20 μm. Low, and short circuit occurred between some wirings.

Comparative Example 4 The conductive paste according to Comparative Example 4 was the same as in Example 1 except that Texanol was used as the solvent.
This is a conductor paste manufactured in the same manner as in the case of (1). Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. However, in this case, the surplus paste could not be removed by polishing or the like, and the accuracy and short-circuit of the finally obtained wiring were investigated in the same manner as in Example 1. As a result, the accuracy was extremely high as the line width of 50 μm ± 20 μm. Low, and short circuit occurred between some wirings.

Comparative Example 5 A conductive paste according to Comparative Example 5 was manufactured in the same manner as in Example 1 except that butyl carbitol acetate was used as a solvent. Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. However, in this case, the surplus paste could not be removed by polishing or the like, and the accuracy and short-circuit of the finally obtained wiring were examined in the same manner as in Example 1 to find that the line width was 5 mm.
The accuracy was extremely low at 0 μm ± 20 μm, and a short circuit occurred between some wirings.

Comparative Example 6 A conductive paste according to Comparative Example 6 was prepared in the same manner as in Example 1 except that 2,2,4-trimethylpentanediol 1,3-monoisobutyrate was used as a solvent. It is a manufactured conductor paste. Using this conductor paste, a wiring pattern was formed on the alumina sintered substrate by the process shown in FIG. However, in this case, the excess paste could not be removed by polishing or the like, and the accuracy and short-circuit of the finally obtained wiring were examined in the same manner as in Example 1, and the line width was 50 μm ± 20 μm.
And the accuracy was extremely low, and a short circuit occurred between some wirings.

[0050]

As described above in detail, in the conductive paste (1) according to the present invention, the solvent is contained in the conductive paste filled in the opening of the positive photoresist layer formed on the ceramic substrate. Since the conductive paste is made of one or more hydrocarbon solvents, such a conductive paste was used in a method of forming a pattern of the positive photoresist layer on the ceramic substrate and forming a wiring pattern using the conductive paste. In this case, the solvent of the conductive paste filled in the opening does not dissolve the positive photoresist layer and does not deform the pattern shape of the positive photoresist layer. Also, even if excess conductive paste adheres to the positive photoresist layer, the conductive paste does not fuse and integrate with the positive photoresist layer, and short-circuits occur between wires after firing. Does not occur. Therefore, a fine wiring pattern with high accuracy can be formed.

In the conductor paste (2) according to the present invention, since the hydrocarbon solvent has a boiling point of 200 ° C. to 350 ° C. in the conductor paste (1), the conductor paste is dried. Not too early, not too late, it is easy to keep the conductor paste at an appropriate viscosity for a long time, and it is easy to handle.

[Brief description of the drawings]

FIGS. 1A to 1G show a conductive paste according to Example 1 of the present invention, and a positive photoresist layer formed on a ceramic substrate by using a photolithography technique;
FIG. 4 is a schematic cross-sectional view showing each manufacturing step when used in a method of forming a wiring pattern using a conductive paste.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Ceramic substrate 12 Positive photoresist layer 15 Opening 16 Conductor paste

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazunari Tanaka 2701-1, Iwakura, Higashi-ku, Omine-cho, Mine-shi, Yamaguchi Prefecture (56) References JP-A-2-240996 (JP, A) JP-A-5-195005 (JP, A) JP-A-3-138807 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H05K 1/09 H01B 1/20 H05K 3/12

Claims (2)

(57) [Claims] 1. A conductive paste filled in an opening of a positive-type photoresist layer formed on a ceramic substrate, wherein the solvent comprises at least one of hydrocarbon solvents. 2. A hydrocarbon solvent having a temperature of 200 ° C. to 350 ° C.
The conductive paste according to claim 1, having a boiling point of: