JPH03212437A - Manufacture of composition containing fine metal powder - Google Patents

Abstract

PURPOSE: To produce a metal fine particle-containing compn. excellent in conductivity and suitable for a conductive adhesive, by introducing a metal having an m.p. within the range for the softening point or m.p. of a polymer (precursor) to the decomposition point or b.p. thereof into the polymer (precursor).

CONSTITUTION: A polymer (e.g.; polyamide resin) is heated and melted and a metal (e.g.; lead, tin bismuth) having an m.p. (47-321°C) within the range from the softening point or m.p. of the polymer (precursor) to the decomposition point or b.p. thereof is introduced into the polymer (precursor and the whole is sheared and stirred to be dispersed and mixed in a fine granular state.

COPYRIGHT: (C)1991,JPO

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a method for producing a polymer containing fine metal particles.

(Conventional technology) Mixtures of metals and polymers are well known.

Various metals have been mixed with various polymers in the form of fibers, powders, flakes, etc. to obtain mixtures with beneficial properties. One of them is coated with a conductive adhesive. Thus, what imparts electrical conductivity is metal in the form of particles or fibers, and for example, the former has been manufactured either by an atomizing method or by mechanically pulverizing. However, both of these had the disadvantage that the metal surface was oxidized by exposure to oxygen in the air before being mixed with the polymer, making it impossible to obtain a conductive adhesive with excellent conductivity or good durability. .

As a solution to this drawback, for example, US Pat. No. 4,533,685 and its divisional application, US Pat. Conductive metallized organic polymer mixtures have been proposed that are prepared by melting together a metal and a polymer in a temperature range between

(Problem to be solved by the invention) The metal-containing polymer produced by this method has succeeded in incorporating metal into the polymer, which has a clean surface without coming into contact with air or oxygen, and the product has impact resistance and heat resistance. It has improved conductivity and can also be used for electromagnetic shielding. However, it cannot be said that the product has sufficient electrical conductivity.

In other words, this metal-containing polymer provides continuity to the metal in the metal-containing polymer so that it can be used not only as a conductive material but also in applications that require mechanical strength such as bearings. In order to form a fibrous body and also impart mechanical strength to the product, the metal is dispersed in the form of strings in the polymer at a relatively low rotational speed of 20 revolutions per minute and at a relatively low temperature of 100 to 150°C. . Therefore, although a product with sufficient mechanical strength can be obtained due to the reinforcing effect of the metal fibrous material, the electrical resistance can only be obtained with a value of around 15 ohm for a 101 diameter disk.

(Means for Solving the Problems) As a result of extensive research into metal-containing polymers that can be used in s'III adhesives and anisotropic conductive films that require particularly excellent conductivity, the present inventors found that: A metal-containing polymer or polymer precursor that has extremely excellent electrical conductivity that has never been seen before by uniformly dispersing fine metal particles with a clean, unoxidized surface in the polymer or polymer precursor. The present invention was achieved by discovering that the following can be obtained.

That is, according to the present invention, the polymer is produced by heating and melting a metal whose melting point is above the softening point or melting point of the polymer precursor and within a temperature range of five degrees above the decomposition point or boiling point at a temperature within the above temperature range. Provided is a method for producing a metal particle-containing composition, characterized in that the metal is introduced into a polymer or polymer precursor, and the metal is dispersed and mixed in the polymer or polymer precursor in the form of fine particles by shear stirring. be done.

The metal used in the present invention, whether a pure metal or a metal alloy, has a temperature above the softening point or melting point and below the decomposition point or boiling point of the polymer or polymer precursor with which the metal is mixed. Any metal that can be melted at
Preferably, it contains zinc, bismuth, magnesium, etc.

Moreover, any of a thermoplastic polymer, a thermosetting polymer before curing, and a thermoelastic substance (elastomer) can be used as the polymer. However, when used as a conductive adhesive,
Epoxy resins, bisphenol A/epichlorohydrin condensation product polyamide resins, and polyimide resins are particularly preferred polymers in terms of adhesive strength, heat resistance, electrical properties, and the like. Furthermore, not only the above polymers but also their precursors can be used.

In the present invention, it is also possible to add a filler before, during, or during the mixing process of the metal and the polymer or polymer precursor. These fillers include, for example, silica-free, clay, calcium carbonate, various mineral powders, carbon black, and the like. These fillers may be appropriately selected in consideration of the desired properties and economic efficiency of the finished product.

In general, the products of the invention will contain 2% to 95% by weight, preferably 5% to 95% by weight, based on the total weight of metal and polymer or polymer precursor.
Use 65% metal.

Further, in the present invention, the metal is uniformly dispersed and mixed in the form of fine particles in the polymer or polymer precursor by means of in-place stirring. Because the metal fine particles at a high concentration are closely dispersed in the polymer or polymer precursor, a metal-containing composition having excellent conductivity not found in conventional products can be obtained.

(Example) Examples of the present invention will be shown below, but the present invention is not limited thereto.

All examples were conducted using conductive adhesives.

Examples 1 to 7 In the epoxy adhesive binder shown in Table 1, high-speed shear stirring was performed using an autohomo mixer M type (manufactured by Tokushu Kika Kogyo ■) at a temperature higher than the melting point of various alloys to form polymers. A metal fine particle-containing composition in which metal fine particles were uniformly dispersed and mixed was produced.

The blending ratio, stirring conditions, etc. are summarized in Table 1.

1) ELA-070: Epoxy resin manufactured by Sumitomo Chemical ■ 2) U-alloy: Alloy manufactured by Osaka Asahi Metal ■ 3) Polyamide resin: Samide 15K (manufactured by Sansho Kagaku ■) Metal fine particle-containing compositions of Examples 2 to 5 Electron micrographs of metal particles obtained by removing epoxy resin from objects are shown in FIGS. 1 to 4 together with magnifications.

It can be seen from the figure that fine particles with a particle size of 20 to 50 μm are formed in the polymer in a closely dispersed state in all cases.

An electron micrograph of the metal particle-containing polyamide resin of Example 7 is shown in FIG. 6 along with the magnification. From the figure, the particle size is 20-7
It can be seen that fine particles of 0μ are dispersed in the polyamide polymer.

For reference, FIG. 5 shows a 100x magnification microscopic photograph of metal particles of paste solder 5S-5030 manufactured by Yamamura Seisakusho, which is assumed to be manufactured by the atomization method. These metal particles also have a diameter of about 20 to 50 μm, which is equivalent to the metal particles of the present invention.
It can be seen that the particle size is .

Application Example 1 Using granules of a composition obtained by dispersing and mixing metal fine particles prepared according to the present invention, a facilitator, a denaturing agent, a viscosity modifier, a filler, and a liquid resin are added to the granules to make the composition conductive. Adjusted the adhesive. A formulation example is shown below.

Dispersion of Example 1 106g Guanidine curing agent DrCY (Nippon Carbide) 6g Nitrile rubber modifier CTBN 1300 (Gutudrich) 4g Anhydrous silica 0.5g Flux rosin 1g Bis A type epoxy resin ELA-07018g Total 135 ．． 5 g of this adhesive
Copper plate thickness 1.6gm+, width 25#ll, length 12
．． 5M and bonded, pressed to 2.0 to 9/cyx2 using a heat press at 220°C, and after pressure curing for 5 minutes, the adhesive strength was measured to obtain a tensile shear strength of 200, ONy/α2. Ta. In addition, the electrical conductivity of this adhesive test piece after curing is 0.1Ω or less, which is the measurement limit (lower limit) of the measuring instrument,
It was shown that this adhesive sufficiently satisfies the performance required for use as a structural conductive adhesive.

Application example 2 Using the adhesive with the mixing ratio shown in application example 1, the width is 0.3
gm+, the pattern shown in FIG. 6 with a void of 0.3 #1 was coated on a polyimide FPC to a thickness of 70 μm, and then cured using a heat press at 220° C. for 3 minutes. Note that the press pressure was 2.0 H/cm2 as in Application Example 1. When the electrical properties of the obtained pattern were examined, it was found that the conductivity was less than 0°1Ω for all 8 poles, and there was no short circuit between different poles, indicating that it had sufficiently satisfactory performance as an anisotropic conductive adhesive. .

Application example 3 The dispersion of Example 7 was molded into a film with a thickness of 50 to 100 μm, which was pasted to a length of 25 jww on two copper plates with a thickness of 1.6 m + and a width of 25 am using an adhesive.
2.0 ℃ heat press/CI! press 2 and 1
It was heated and melted for a minute. Shear adhesive strength at room temperature 37/
It was cm2. The conductivity of the adhesive is determined by the measurement limit of the measuring device (
(lower limit) of 0.1 Ω or less, indicating that this adhesive satisfies sufficient performance for use as a hot-melt conductive adhesive.

Application Example 4 50 g of the dispersion of Example 7, 9 g of the dispersion of Example 2, and 1 g of Futx resin were melt-mixed and formed into a film with a thickness of about 50 to 100 μm, with a width of 0.3 mm and a gap of 0 as shown in FIG. A .3jw polyimide FPC was attached and melted and bonded using a heat press at 220°C for 1 minute. Press pressure is 2.0Kg/C112. When the electrical properties of the obtained pattern were examined, the conductivity was 0.1Ω or less for all 8 poles, and there was no short circuit between different poles, indicating that the pattern had sufficiently satisfactory performance as a hot-melt concrete conductive adhesive. Understood.

(Effects of the Invention) As explained above, the metal fine particle-containing composition of the present invention is extremely useful as a conductive material, particularly a conductive adhesive and an anisotropic conductive film.

Since the metal is uniformly and closely dispersed in the form of fine particles in the polymer composition, it exhibits excellent electrical conductivity.

Furthermore, since the surface of the metal fine particles is covered with a polymer or a polymer precursor, resistance to corrosion is improved.

Furthermore, since the metal and polymer or polymer precursor are melted together and metal particles are formed by high-speed shear stirring, the metal does not come into contact with air or oxygen at high temperatures, and the metal particles with a clean surface are dispersed. As a result, a product with excellent electrical conductivity is obtained, which is extremely useful in addition to electrically conductive adhesives, for example in electromagnetic interference shielding (EMI shielding).

[Brief explanation of drawings]

Figures 1 to 4 are electron micrographs of metal fine particles produced according to the present invention, Figure 5 is a microscope photograph of metal particles of base solder, and Figure 6 is an electron microscope photograph of a polyamide resin containing metal fine particles. This is a photograph, and FIG. 7 is a diagram illustrating a pattern provided on a polyimide FPC in order to perform an electrical property measurement test of a conductive adhesive using a polymer containing metal fine particles of the present invention.

Claims (6)

[Claims] (1) A polymer or A method for producing a composition containing fine metal particles, which comprises introducing the metal into a polymer precursor and dispersing and mixing the metal into the polymer or polymer precursor in the form of fine particles by shear stirring. (2) The method for producing a composition containing fine metal particles according to claim 1, wherein the metal has a melting point of 47°C to 321°C. (3) The method for producing a composition containing fine metal particles according to claim 1, wherein the metal is bismuth, cadmium, gallium, selenium, lead, or tin. (4) The method for producing a composition containing fine metal particles according to claim 1, wherein the metal is an alloy containing one or more metal species selected from the group of lead, tin, zinc, bismuth, and magnesium. (5) Claim 1, wherein the polymer precursor is an epoxy resin.
, 2, 3 or 4. The method for producing a composition containing fine metal particles. (6) Claims 1 and 2, wherein the polymer is a polyamide resin.
, 3 or 4. The method for producing a composition containing fine metal particles.