JP2000011759A - Conductor composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paste having no shrinkage difference from a laminate substrate and exhibiting low resistivity at the time of being fired after the paste is packed into a through hole in the ceramic laminate substrate, by using complex particles, in particular, of silver and magnesium oxide, in relation to a conductor composition comprising conductive metallic particles, an adhesive agent, an organic solvent, and a surfactant. SOLUTION: In the case of a conductor composition comprising conductive metallic particles, a glass powder of high softening temperature and a resin, further, small amounts of organic solvent and surfactant, the conductor composition for use in filling a through hole is characterized in that a glass powder of relatively high softening temperature is jointly used, that the amount of the organic solvent in the conductor composition is as slight as 4.0 to 6.0 wt.%, that complex particles, in particular, of silver and magnesium oxide are used, and that the concentration of solid content in the conductor composition is as high as 88 to 93 wt.%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a conductor composition for forming an electric circuit, and more particularly to a paste for filling a through hole for circuit wiring formed on a ceramic laminated substrate, which has a low resistance value. The present invention relates to a conductor composition which shows no change in volume during firing and has no difference in shrinkage from a ceramic laminated substrate.

[0002]

2. Description of the Related Art In recent years, the application technology of noble metal pastes for the electronics industry has been rapidly expanding, and various kinds of noble metal particles are used singly or in combination as a paste material. Noble metal paste, noble metal powder or noble metal resinate as a conductive functional material, organic or inorganic binder,
It is kneaded and dispersed in a viscosity imparting medium composed of a metal oxide to form a paste.

[0003] As a method of forming a metal film on electrodes, conductors and resistors as electronic parts, a method of forming a metal film from a base metal or a precious metal organometal (ink), or a method of forming a thin film by wet plating typified by electroplating. There are a method of forming a thin film by dry plating such as a vacuum evaporation method, a chemical vapor deposition method, and sputtering, and a thick film method of forming a metal film using a base metal or a noble metal paste.

[0004] Conductive pastes widely used in the field of electronic parts are generally used for conductive circuits of electronic parts. The conductive noble metal particles in the component are mainly silver, palladium and other noble metals and base metals, but when filled in through holes, the shrinkage during firing of the conductive powder exceeds the adhesive strength to the ceramic laminated substrate Therefore, there is a problem that the conductor falls out of the through hole.

[0005] In addition, when filling the conductive paste into the pores of about 0.4 mm, in order to prevent dimensional tolerances of the ceramic laminated substrate and set friction at the time of filling the paste, a plate having a slightly larger pad pattern is used. The holes are filled with a conductive paste. At this time, the protruding conductor is likely to be chipped, so that it is necessary to polish the ceramic laminated substrate and perform a planarization process. In any case, the key to solving the problem is to reduce the difference in shrinkage between the substrate and the conductive metal during firing.

For example, Japanese Patent Application Laid-Open No. 7-2
No. 35215 and JP-A-9-46013, which fill a through-hole formed in a ceramic laminated substrate,
As the conductive paste to be fired, the former adds 0.1% by weight or more of rhodium powder to silver or copper powder,
In the latter case, the conductive powder contains a swelling agent and a coloring agent, and an aluminosilicate compound or a titanate compound or the like is used as the swelling agent. A method using titanium or another adhesion improving aid is disclosed. However, these conductor compositions are not only different from those according to the present invention, but also the conductive metals are simply mechanically kneaded and dispersed.

In addition, JP-A-1-107759 and JP-A-1-107592 disclose that a vehicle in which silver powder and rhodium powder are dispersed contains antimony oxide as an inorganic binder and substantially contains glass frit. An electric circuit board coated with a conductor composition not containing is introduced. This one, as well as the vehicle component, the purpose of use,
An object of the present invention is to improve solder wettability, which is completely different from the present invention.

Japanese Patent Application Laid-Open No. 4-206401 discloses an inner layer silver paste composition for a low-temperature fired multilayer substrate.
This uses a silver paste composition containing a low softening point glass frit of 300 to 450 ° C., a high softening point glass frit of 580 to 850 ° C., and a powder of alumina, zirconia, magnesia, or the like. The softening point of the glass is lower than 850 ° C., and silver and magnesia are used by simply mechanically kneading and dispersing, and are not composite particles of silver and magnesium oxide (magnesia), but are peeled off when bonding green sheets. It only aims at improving the warpage of the substrate. Therefore, it does not teach solving the problem of shrinkage of the through hole filling composition.

Japanese Unexamined Patent Application Publication No. 8-64029 discloses another terminal electrode paste. However, the present invention has an object to form a terminal electrode of a ceramic capacitor, and is independent of filling of a through hole. Silver and magnesia are contained as the conductive paste, but also by mechanically kneading and dispersing two types of silver particles and magnesia particles, the silver and magnesium oxide (magnesia) of the present invention are also used.
The composite particles of the present invention are similar to the present invention in terms of the problem to be solved and the function and effect as described later.

As described above, there are few techniques for filling through holes in a ceramic laminated substrate. Even if it is recognized that the conventional technology is to improve the shrinkage of the ceramic laminated substrate, sufficiently satisfactory results are still obtained. The fact is that there is no current situation, and as the use of OA equipment increases, a circuit board of higher and higher quality is demanded, and this improvement is an immediate problem.

[0011]

In today's demand for smaller, lighter, and higher-performance electronic components, shrinkage during firing of a ceramic laminated substrate, which could not be achieved by the prior art, is prevented. An object of the present invention is to focus on improvement of a conductive composition for filling through holes to obtain high-quality circuit wiring, and to enable high-density mounting.

[0012]

The configuration of the present invention is as follows. 1 A conductive composition comprising conductive metal particles, a glass powder having a high softening temperature, a resin, an organic solvent and a surfactant, wherein the conductive metal particles comprise composite particles of silver and magnesium oxide having a high solid content concentration. A conductor composition comprising: 2 In the conductor composition, the solid content concentration of the conductive metal particles is 8
2. The conductor composition according to item 1, wherein the content is 8 to 93% by weight. (3) The conductor composition as described in any one of (1) and (2) above, wherein magnesium oxide in the conductor composition is 0.5 to 4.0% by weight based on silver. 4 The glass powder having a high softening temperature has a softening temperature of 950-11.
4. The conductor composition according to any one of the above items 1 to 3, wherein the conductor composition having a softening temperature of 800C and a softening temperature of 800C to 900C are used in combination. (5) The conductor composition as described in any one of (1) to (4) above, wherein the glass powder having a high softening temperature is composed of boron and silicon and calcium, boron and silicon. (6) The conductor composition as described in any of (1) to (5) above, wherein the organic solvent is used in a range of 4.0 to 6.0% by weight in the conductor composition. (7) The conductor composition as described in any one of (1) to (6) above, wherein a cationic surfactant is used in the conductor composition in an amount of 1.5 to 4.0% by weight.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The silver-based conductor composition used in the present invention is different from conventional conductor compositions in that AgMgO is used in which silver particles are combined with a small amount of magnesium oxide to form a single body. Is an electron micrograph attached separately as FIG. 1), a surfactant is added to a small amount of terpineol to form a conductive paste. The paste composed of metal particles has a solid content as high as 93% by weight, and since it is a composite particle, has excellent dispersibility, and the paste viscosity is as low as 150 Pa · s to 300 Pa · s (Pascal second). , Screen printing or metal mask printing is possible. Therefore, the filling degree of the conductive paste into the through-hole is extremely high, combined with the solid solubility of silver particles and the high glass softening temperature. It has become possible.

A in which magnesium oxide is composited with silver particles
The outline of the production method of gMgO is as follows, using a spray pyrolysis method, spraying an aqueous solution of silver nitrate and magnesium nitrate in an electric furnace in the form of water droplets, and heating in an atmosphere of 950 ° C.
At the same time as the water is expelled, thermal decomposition occurs to obtain particles in which magnesium oxide crystals are combined and integrated around the silver particles. The composite particle diameter is occupied by 2 to 4 μm, and magnesium oxide fine particles are compositely integrated around silver. The ratio of magnesium oxide to silver is 0.1 μm.
5 to 4.0% by weight. The composite particles can be made in a so-called dense state without voids when the paste is fired.

The paste disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 8-64029 is a paste for bonding terminal electrodes of a ceramic capacitor. Unlike the paste for filling through holes of the present invention, silver particles and magnesia particles are simply mechanically kneaded. In addition to the lack of density, the dispersion state of silver particles, magnesia particles, glass particles, etc. is coarse, and the maximum printable solid concentration even when dispersed in an organic solvent is 85% by weight. It is below. Since this is for terminal electrode bonding, it is considered that there is no need to desire any more.

Next, in the present invention, two types of glass having a high softening temperature are used in combination. When a glass having a softening temperature of 850 ° C. or lower is used, it has good adhesion to a ceramic laminated substrate, but melts rapidly during firing. The paste shrinks sharply during the solidification stage. On the other hand, if the temperature greatly exceeds 1000 ° C., the firing time is prolonged, and the compatibility with the ceramic laminated substrate is reduced. Therefore, in the present invention, the temperature is 800 to 900 ° C. and 950 to 1100 ° C. (preferably, calcium and The combined use of 850 ° C. composed of boron and silicon and 1063 ° C. composed of boron and silicon) greatly enhances the solid solution of the silver composite particles and the compatibility with the ceramic laminated substrate, and also shrinks on this surface. Thus, the problem of the conventional laminated substrate could be improved.

The binder resin for the printing vehicle is, for example, ethylcellulose or ethylhydroxyethylcellulose as the cellulosic resin, and polymethacrylate or polyacrylate as the acrylic resin. Ethyl cellulose, which is empirically known to have no adverse effect on other substances, is mainly used.

Organic solvents include terpenes, terpineols,
Butyl carbitol, butyl carbitol acetate,
Hexylene glycol, diethyl phthalate and the like can be used without any problem, but terpineol and butyl carbitol are mainly used. The amount used is 4.
In the range of 0 to 6.0% by weight, if it exceeds 6.0% by weight, it is easy to print on the ceramic laminated substrate, but on the other hand, the degree of shrinkage increases as the amount of escaping increases, and if it falls below 4.0% by weight. Although the shrinkage is small, it becomes technically impossible on the printing surface, and it is preferably 5.0% by weight.

The surfactant may be cationic, anionic,
Both amphoteric and nonionic types can be used, but those having a high activity particularly in lowering the surface tension and dispersing action are preferred because of the small amount used. Among them, cationic ones are preferred from the results of experiments, and duomin and esomine (both trade names of products manufactured by Lion Corporation) are added in a ratio of 1: 3 to 1.5 to 4.0 weight parts with respect to the conductor composition. %use.

As described above, the present invention is primarily intended for silver
The use of composite particles of magnesium oxide has great significance, and a vehicle that is easy to handle and has good dispersibility can be obtained. Then, since the solid content concentration of the paste to be printed on the ceramic laminated substrate is maximized, and the viscosity is reduced and the surface tension is reduced by adding a surfactant, the paste can be densely filled. Paste viscosity is 150 ~ 300P
In a.s, suitable screen printing and metal mask printing are possible even if the solid content concentration is as high as 93% by weight. next,
This will be described in detail based on an embodiment.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the outline of the method for producing the conductive metal composite particles of the present invention will be described. An aqueous solution of silver nitrate and magnesium nitrate is sprayed into an electric furnace having an internal temperature of 950 ° C. in the form of water droplets. The decomposed material is collected separately to obtain silver-magnesium oxide composite particles. Its particle size is 2-4 μm
In this order, a large number of small-sized magnesium oxide fine particles are integrated with silver particles. This is apparent from the electron micrograph of FIG. 1 attached separately.

The conductive metal particles, glass powder as an adhesive to the ceramic laminated substrate, and polymerized ethyl cellulose as a paste dispersant, an organic solvent and a surfactant are mixed and dispersed to obtain a high-concentration and low-viscosity liquid. This was used as a printing paste. Table 1 below shows the breakdown of additives in each example. It should be noted that a combination of silver and rhodium may be used as the conductive metal particles instead of silver and magnesium oxide composite particles.

[0023]

[Table 1] In Table 1, the surfactant was used in a ratio of duomin 1: esomin3. The organic solvent used was terpineol.

Next, a conductor composition based on the above composition is
Using a stainless steel metal mask having a thickness of 0.125 mm, printing is performed on a 96% alumina substrate having a thickness of 0.335 to 0.8 mm and having a thickness of 0.335 to 0.8 mm, and a temperature of 120 ° C. for 10 minutes. After drying, 850 ° C in an electric furnace
Was fired. After cooling, the results shown in Table 2 were obtained.

[0025]

[Table 2] In Table 2, the viscosity was measured with a Brookfield HBT viscometer. The adhesion was observed by piercing the paste with a needle-like body.

[0026]

[Comparative Example] As conductive metal particles, instead of composite particles of silver and magnesium oxide, silver and palladium particles commonly used in the past, and those obtained by mechanically kneading and dispersing silver and platinum particles were used. Other than the above, all were performed in the same manner as in the examples. In the case where silver and magnesium oxide are mechanically kneaded and dispersed, the amount of magnesium oxide increases, and the fired film becomes rough, resulting in poor electrical characteristics.

[0027]

As described in detail above, the present invention has completely solved the problem in the technique of filling through holes in a ceramic laminated substrate, which has conventionally been a problem. That is, the paste to be printed on the substrate is a composite particle of silver and magnesium oxide, so that it can be densely dispersed and easy to handle, and the addition amount of the organic solvent is small, so that the maximum solid content is small. The concentration can be increased, and the degree of filling of through holes is high due to the decrease in viscosity and the decrease in surface tension.
No shrinkage was observed due to the small size of the scattered matter even after firing at a high temperature. Therefore, a particularly remarkable function and effect can be obtained, for example, a ceramic laminated substrate having good dimensional stability without deformation and a low resistance value can be obtained.

[Brief description of the drawings]

FIG. 1 shows 200 particles of a composite particle of silver and magnesium oxide.
00x electron micrograph

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Yoshinobu Watanabe 2453-21 Iiyamadainooka, Atsugi-shi, Kanagawa F-term in the Atsugi Plant of Tanaka Kikinzoku Kogyo Co., Ltd. 4E351 BB31 BB49 CC11 CC22 DD02 DD05 DD08 DD28 DD31 DD52 DD58 EE02 GG09 GG12 GG15 5G301 DA02 DA03 DA33 DA34 DA36 DA37 DA40 DA42 DD01

Claims (7)

[Claims] 1. A conductive composition comprising conductive metal particles, glass powder and resin having a high softening temperature, an organic solvent and a surfactant, wherein the conductive metal particles are composed of silver and magnesium oxide having a high solid content concentration. A conductor composition comprising body particles. 2. The conductor composition according to claim 1, wherein the solid content of the conductive metal particles in the conductor composition is 88 to 93% by weight. 3. The conductor composition according to claim 1, wherein the content of magnesium oxide in the conductor composition is 0.5 to 4.0% by weight based on silver. 4. The glass powder having a high softening temperature has a softening temperature of 9%.
50-1100 ° C and softening temperature 800-900 ° C
4. The combination according to claim 1, wherein
The conductor composition according to any one of the above. 5. The conductor composition according to claim 1, wherein the glass powder having a high softening temperature comprises boron and silicon, and calcium, boron and silicon. 6. The organic solvent may contain 4.0 to 6.
6. The composition according to claim 1, wherein said compound is used in a range of 0% by weight.
The conductor composition according to any one of the above. 7. The conductor composition according to claim 1, wherein the surfactant comprises a cationic surfactant in an amount of 1.5 to 4.0% by weight in the conductor composition. .