JPH0649269A - Flaky ag-pd alloy filler material having electrical conductivity and product containing the filler - Google Patents

Abstract

PURPOSE:To provide an electrically conductive filler material resistant to the migration of silver. CONSTITUTION:The objective flaky filler material for imparting electrical conductivity is composed of an Ag-Pd alloy having an average particle diameter of 0.1-100mum, an aspect ratio (ratio of the minor axis to the major axis of the flaky plane) of 1-0.3 and a thickness of <=5mum and containing 1-50wt.% of Pd and the remaining part of Ag and inevitable impurities and is resistant to the migration of Ag. The filler material gives a resin, polymer, paste, coating material and ink resistant to the migration of silver and having high electrical conductivity at a low cost.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a metal filler material for imparting conductivity to polymers such as resins and rubbers, pastes, paints or inks, and the above-mentioned metal filler material having conductivity. Regarding products.

[0002]

2. Description of the Related Art Conventionally, Ag powder, scaly Ag powder, copper powder, etc. have been used as a metal filler material for imparting conductivity to polymers such as resins and rubbers, and conductive paste, paint, Similarly, Ag powder, scaly Ag powder, copper powder, mixed powder of Ag and Pd, mixed powder of Ag and Pt, and the like are used for ink and the like. As a method for producing the flaky metal powder, for example, JP-A-61-155471
Japanese Patent Laid-Open No. 5-52049.

[0003]

However, in the case of Ag powder or scale-like Ag powder as a metal filler material for imparting conductivity to a polymer such as resin or rubber, Ag powder in a polymer such as resin or rubber is Migration (transition phenomenon) is likely to occur, and there is a problem that the conductive characteristics become unstable.

Further, when the copper powder is used, migration is unlikely to occur, but there is a problem that the copper powder is oxidized inside the polymer and the conductive characteristics are deteriorated.

Ag and Pd are used as this kind of metal filler material.
A method of solving the above-mentioned problems can be considered by using the above alloy powder or the alloy powder of Ag and Pt. However, in order to exhibit conductivity in a polymer such as resin or rubber, the alloy particles should be in contact with each other. Only small particles having a small diameter have to be classified, and a large amount of loss occurs due to the classification, resulting in an increase in manufacturing cost.

[0006] Ag powder, scale-like Ag powder and copper powder used in conductive pastes, paints and inks are applied as an electronic component on a ceramic substrate and fired to form a circuit by these metals. Had a problem that the conductive characteristics became unstable due to migration, and the copper powder had a problem that the conductive characteristics deteriorate due to oxidation.

The mixed powder of Ag and Pd and the mixed powder of Ag and Pt are applied and fired on a ceramic substrate as an electronic component, for example. The firing temperature at this time is generally 800 ° C. or higher. That is, the mixed powder of Ag and Pd or the mixed powder of Ag and Pt is melted on the substrate to form an alloy, and migration of Ag is prevented.

The technical problem in this case is, for example, A
When g85wt% and Pd15wt% or Ag95wt% and Pt5wt% are mixed, it is difficult to mix both powders and uniformly disperse in paste, paint and ink,
Microscopically observing the circuit obtained by coating and firing on a ceramic substrate, there was unevenness in the formation of the alloy, and it was difficult to completely prevent migration.

An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide an inexpensive conductive metal filler material having excellent characteristics and a product using the same.

[0010]

In order to achieve the above object, the inventors of the present invention have conducted extensive studies and found that the powder itself is A
If it is a g-Pd alloy and its shape is scale-like, A
It was found that it is extremely effective as a conductive metal filler material that is unlikely to cause migration of g, and that it is more advantageous to enhance the conductive efficiency by orienting this scale-like powder into a layer in the poilimer. The invention was completed.

[0011]

The present invention has an average particle diameter of 0.1 to 100 μm.
And a scale-like Pd of 1 to 50 wt% with a ratio of the minor axis to the major axis of 1 to 0.3 and a thickness of 5 μm or less, preferably 1 μm or less.
A conductive filler composed of the balance Ag and unavoidable impurities is provided. The conductive filler of the present invention is preferably produced by mechanically flattening a powder obtained by rapidly cooling a molten Ag-Pd alloy. The present invention also provides the conductive filler material,
Provide a conductive polymer (including rubber), a conductive paste, a paint or an ink.

[0012]

The structure and operation of the present invention will be described. The conductive filler of the present invention is obtained by pulverizing substantially spherical particles having an average particle diameter of 5 to 150 μm obtained by a water atomizing method or the like with a pulverizer using balls or the like to form flakes. The degree of crushing and flaking can be determined by the particle size of the balls, the crushing time and the type of solvent used.

The scale-like powder obtained as described above has an average particle size of 0.1 as measured by a laser scattering method.
˜100 μm, the ratio of the minor axis to the major axis of the scaly plane is 1 to 0.
3. Thickness is 5 μm or less, preferably 1 μm or less. The alloy composition of the Ag-Pd particles is Pd 1 to 50 wt% balance Ag and inevitable impurities.

The reason for the above limitation is that if the average particle diameter is less than 0.1 μm, mutual aggregation of the particles occurs and it is difficult to uniformly disperse the particles, and if it exceeds 100 μm, there is a problem in conductivity. Further, when the ratio of the minor axis to the major axis of the scaly plane is out of the specified range, or when the thickness exceeds 5 μm, the effect as a conductive filler due to scalyness decreases. And P
If it is less than d1 wt%, the Ag migration resistance is not practical, and if it exceeds 50 wt%, the above-mentioned effect is saturated and it becomes unnecessarily expensive.

By using Ag-Pd particles in the form of flakes as described above and uniformly dispersing them in, for example, an acrylic resin, a silicone resin, a polyurethane resin using a roll mill or the like, a conductive polymer is obtained. can get.
Further, the scale-like Ag-Pd particles are premixed with, for example, a polymer (for example, a polyurethane resin) and a solvent, and then uniformly dispersed by using a roll mill or the like to obtain a conductive paste, a paint or an ink. To be Further, by applying the magnetic field and / or pressure to orient the dispersed powder in a layered manner, contact resistance can be reduced and conductive efficiency can be increased.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The constitution and effect of the present invention will be specifically described by way of examples, but the present invention is not limited thereto.

Example 1 8 kg of silver and 2 kg of palladium were melted using a graphite crucible under an Ar gas atmosphere, and the melt was subjected to a high pressure water atomization method to form a substantially spherical Ag-Pd having an average particle size of 15 μm.
Alloy particles were obtained.

200 g of the obtained particles were pulverized and flattened by a wet ball mill pulverizer (using 800 g of methyl alcohol as a solvent and 2 g of stearic acid as a dispersant) for about 62 hours.

As a result of measuring the obtained flat powder by a laser scattering method, the average particle diameter was 1.5 μm. Also,
From the SEM photograph shown in FIG. 1, it was confirmed that the ratio of the minor axis to the major axis of the scale plane was 0.55, and the thickness of the scale was 0.3 μm. Such a scale-like Ag-Pd alloy had a powder Not reported so far.

68 wt% of this powder in silicone rubber
Compound with a roll mill at a ratio of
The film was cured at 1 ° C. for 1 hour to produce a thin film having a thickness of 70 μm. The volume resistance value of this thin film was 1.5 × 10 ⁻³ Ω · cm. In addition, a magnetic field applied to this dispersed powder before hardening is 8 × 10 ⁻⁴ Ω · cm.
The volume resistance of When this scale-like powder was provided to the user as a sample, it was reported that the time until migration occurred was about 20 times that in the case of using silver powder of the same particle size.

The scale-like Ag-Pd alloy powder produced above was mixed with a polyurethane resin at a ratio of 70 wt%,
Add an appropriate amount of solvent (cyclohexane and toluene) and disperse with a sand mill to make a paste with a viscosity of 750 cps, apply it to a ceramic substrate, and cure it in an electric furnace at 80 ° C for 2 hours, 180 ° C for 4 hours 30 minutes. A baking treatment was performed to form a coating film. The surface resistance of this coating is 1.0 x
It was 10 ⁻³ Ω / □. In this case as well, the powder obtained by orienting the powder in a layer shape by a magnetic field before curing is 7.2 × 10 ⁻⁴ Ω /
The surface resistance value of □ is shown.

Example 2 8 kg of silver and 2 kg of palladium were melted in an Ar gas atmosphere using a graphite crucible, and the melt was subjected to a high pressure water atomization method to form a substantially spherical Ag-Pd having an average particle size of 50 μm.
Alloy particles were obtained.

200 g of the obtained particles were crushed and flattened by a wet ball mill (using 920 g of methyl alcohol as a solvent and 8 g of stearic acid as a dispersant) for about 28 hours.

The particle size of the obtained flat powder was measured by a laser scattering method, and the average particle size was 15 μm. The ratio of the minor axis to the major axis of the scale plane is about 0.7, and the thickness of the scale is 1 μm.
Met.

A coating film was prepared from this powder in the same manner as described in Example 1, and the surface resistance value of the obtained coating film was 5.4 × 10 ⁻³ Ω / □. . In this case as well, the powder obtained by orienting the powder into a layer by the magnetic field before the coating was cured exhibited a surface resistance value of 4.1 × 10 ⁻³ Ω / □. This powder was also provided to the user, but it was reported that the time until migration similarly occurred was about 20 times as much as that of the plain silver powder having the same particle size as the product of Example 1.
FIG. 2 shows the results of measuring the surface resistance by making coating films having different filling rates of the Ag-Pd alloy powder. As a comparison, the results of a similar test in which Ag-Pd alloy powder having the same composition but an average particle size of about 15 μm, but having a substantially spherical shape (powder before grinding and flattening in Example 1) are used are shown.

Example 3 8 kg of silver and 2 kg of palladium were melted in a graphite crucible under an Ar gas atmosphere, and the molten liquid was subjected to a high pressure gas atomization method to obtain a nearly spherical Ag-Pd alloy powder having an average particle size of 150 μm. 200 g of the powder was pulverized and flattened for about 15 hours by a pulverizer using a wet ball (using methyl alcohol as a dispersion medium). As a result of measuring the particle size of the obtained flat powder by a laser scattering method, the average particle size was 100 μm. The ratio of the minor axis to the major axis of the scale plane was about 0.7, and the thickness of the scale was 5 μm.

A filling amount of this powder in silicone rubber 56w
A coating material was prepared by kneading with a roll mill at t% (the maximum amount that can be filled in the silicone rubber) and further post-treated at 180 ° C. for 4 hours and 30 minutes to prepare a thin film having a thickness of 200 μm. The surface resistance value of the thin film was 8.2 × 10 ⁻³ Ω / □.
In this case as well, the one in which the powder was oriented in a layer before being hardened by the magnetic field showed a surface resistance value of 7.5 × 10 ⁻³ Ω / □. When this powder was provided to users, it was reported that the time required for migration to occur was about 20 times longer when a thin film was formed than the conventional silver powder.

Example 4 As in Example 1, except that crushing and flattening were carried out for about 25 hours. As a result of measuring the particle size of the obtained flat powder by a laser scattering method, the average particle size was 5.3 μm. The ratio of the minor axis to the major axis of the scale plane is about 0.7, and the scale thickness is 1
was μm. Fill the silicone rubber with this powder 56
wt% (maximum amount that can be compounded with silicone rubber)
Then, knead with a roll mill to make a paint, and
After treatment for 4 hours and 30 minutes at 80 ℃, thickness 200μm
A thin film of The volume resistance value of this thin film is 3.6 × 1.
It showed 0 ⁻³ Ω · cm. Also in this case, the film oriented in a layer by a magnetic field before the thin film is cured has a thickness of 1.9 × 10 ⁻³ Ω /
It was □. This powder was also provided to the user, but it was reported that the time until migration similarly occurred was about 20 times as much as that of the plain silver powder having the same particle size as the product of Example 1.

[0029]

EFFECTS OF THE INVENTION Since the present invention is constructed as described above, it is possible to obtain a conductive filler material in which migration of silver is unlikely to occur. It is possible to provide resins, polymers, pastes, paints and inks that have good properties and are inexpensive, and are extremely useful in industry.

[Brief description of drawings]

FIG. 1 is a scanning electron microscope (SEM) photograph showing the structure of the conductive filler material particles of the present invention produced in Example 1.

FIG. 2 is a graph showing the surface resistance values of coating films prepared by changing the filling amount of Ag-Pd powder of Example 2 in comparison with the case of powder of the same substance but the same average particle diameter and only spherical shape. is there.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] April 26, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location H01B 1/00 H 7244-5G 1/22 Z 7244-5G

Claims (5)

[Claims] 1. A conductive material having an average particle size of 0.1 to 100 μm, a ratio of a short axis to a long axis of 1 to 0.3, and a thickness of 5 μm or less of scaly Pd of 1 to 50 wt% balance Ag and inevitable impurities. Filler material. 2. The conductive filler material according to claim 1, which is obtained by mechanically flattening a powder obtained by rapidly cooling a molten Ag—Pd alloy. 3. A conductive polymer comprising the conductive filler according to claim 1 or 2. 4. A conductive paste, paint or ink containing the conductive filler material according to claim 1. 5. The conductive polymer material according to claim 3, wherein the conductive filler is layered in the polymer.