JPS61215672A - Functional, electrically conductive bonding material - Google Patents

Abstract

PURPOSE:To provide the titled bonding material which connects leads to each other electrically and mechanically and controls irreversibly electrical conductivity by heating or irradiation with electromagnetic wave, consisting of synthetic metallic particles and a high-molecular material compsn. CONSTITUTION:At least 50vol% synthetic metallic particles (e.g. polyacetylene doped with perchlorate ion or arsenic hexafluoride ion) having a particle size of 0.03-3mum and electrical conductivity of 10<-2>-10<6>s/cw are blended with a high-molecular material compsn. contg. a synthetic resin such as epoxy resin or alkyd resin, a hardener, carbon particles, metallic particles, insulating particles, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a conductive adhesive for wiring and connections used in the manufacture and use of electronic components, electronic circuits, and semiconductor integrated circuits.

Prior Art Conventional conductive adhesives are made by kneading gold, silver, or carbon particles or fibers into a polymer composition, and are widely used in the above fields as materials with conductive and adhesive functions. There is.

Problems to be Solved by the Invention Conventional conductive adhesives are merely electrically conductive, and their electrical conductivity cannot be irreversibly controlled by external energy. Therefore, for example, in gigantic bonding, which is widely used in electronic devices such as semiconductor elements, thermal heads, and liquid crystal display elements,
With the increase in integration, there has been a problem in which short circuits between lines occur frequently due to the solder and conductive adhesive used protruding from the bonded parts. This is a problem with the prior art in that the protruding portion cannot be insulated.

Means for Solving the Problems The adhesive is composed of a polymer composition containing synthetic metal particles, and the polymer composition preferably contains carbon particles.

Function The functional conductive adhesive of the present invention is made of a polymer composition containing synthetic metal particles, and in addition to the function of mechanically and electrically connecting leads to each other, the functional conductive adhesive material of the present invention has the function of mechanically and electrically connecting leads. It has the function of irreversibly controlling its conductivity.

This irreversibility is brought about by the synthetic metal distributed in particulate form, which is a feature of the present invention.

In other words, when synthetic metals are heated or exposed to electromagnetic waves, the higher-order structure of molecules that contribute to conductivity and the concentration and distribution of impurities change, resulting in changes in conductivity.

Examples The adhesive material of the present invention has various industrial effects due to the above-mentioned controllability, and examples thereof will be described below.

The technical idea of the present invention will be explained with application examples and configuration examples, and finally with specific examples.

First, when the functional conductive adhesive according to the present invention (hereinafter simply referred to as adhesive) is used for the Guyang bonding, rational bonding can be realized. In other words, if the adhesive of the present invention is used in the same manner as before and electromagnetic waves are irradiated after bonding, the leads will shield electromagnetic waves at the bonded parts where electrical connection is required, maintaining conductivity and eliminating the cause of short circuits. The adhesive material in the protruding portion is insulated for the above-mentioned reason.

Therefore, the cause of short circuits can be completely eliminated, and the present invention solves at once the problems that have been a concern as electronic devices become more highly integrated.

Next, as a representative example, we will provide a new method for wiring inside printed circuit boards and ICs. That is, conventional printed circuit boards have been made by etching or additive methods, but printed circuit boards can be made very easily by simply uniformly applying the adhesive of the present invention and then irradiating electromagnetic waves using a mask. Similarly, for wiring inside an IC, the wiring can be completed by applying the adhesive of the present invention to the wafer using a spinner and then irradiating electromagnetic waves using a mask, which shortens the conventional process at once.
Since no unevenness is formed in the wiring, it is extremely convenient for manufacturing laminated three-dimensional ICs.

Both of the above two representative examples irreversibly define the conductive part and the non-conductive part, but the adhesive of the present invention can also control the conductivity at will, and its initial stage The conductivity of the material can also be selected from a very wide range. First, if metal or carbon particles are mixed in, the conductivity will increase, if insulating particles are mixed in, the conductivity will be decreased, and the absorbency of electromagnetic waves can be controlled arbitrarily. However, in either case, the range must not be exceeded to maintain irreversibility, which is a feature of the present invention. Furthermore, the initial value is also adjusted by the selection of synthetic metal. The electrical conductivity of the synthetic metal is in the range of 10 to 10 S/crIL, and a value suitable for the purpose is arbitrarily selected. In this way, the initial conductivity of the adhesive of the present invention is adjusted, and the conductivity after being irreversibly changed is adjusted by the degree of heating or electromagnetic wave irradiation.

The synthetic metals referred to in the present invention include all metals whose conductivity changes irreversibly upon heating or irradiation with electromagnetic waves, as described above, and representative examples include the following. For example, organic conjugated systems such as polythenylene, polypyrrole, polyacetylene, and polyberinaphthalene doped with perchlorate ions or arsenic hexafluoride ions, inorganic conjugated systems such as graphite or polythiazyl doped with iron chloride or bromine, polyvinyl carbazole, and metal phthalocyanine. There are non-conjugated systems doped with trinitrofluorenone and iodine. Among these, polymer systems containing impurities are particularly excellent in terms of stability.

As mentioned above, this synthetic metal exhibits irreversibility as a single substance, but it has been found that when it is further made into particles, the irreversibility becomes more pronounced.

Although the detailed principle behind this effect is not clear, it is presumed that the increase in surface area makes it easier for the above-mentioned impurities to move. From this point of view, it is expected that the smaller the particles, the better the effect, but from the viewpoint of practical properties as an adhesive, a size of 0.03 to 3 μm is preferable.

There are various methods for irreversibly changing the conductivity of the adhesive of the present invention, but if you want to clearly distinguish between conductive parts and non-conductive parts, it is desirable to irradiate electromagnetic waves in an adiabatic state. Basically, any type of electromagnetic wave can be used, but a wide range of wavelengths from ultraviolet to far infrared can be used, and the selection will be more effective if you take into account its compatibility with the absorption wavelength of the adhesive of the present invention. It is true. From these points of view, it is preferable to use xenon lamp light, laser light, or infrared light. The volume ratio of the particle component is preferably 80% or more when sufficient conductivity is required, and 60 to 80% when adhesive strength is required rather than conductivity.

Furthermore, the particle component can be used in combination with not only synthetic metal particles but also metal particles or carbon particles, in which case,
Due to the high conductivity of the particles used in combination, it has the advantage that low conductivity particles can also be used as synthetic metal particles. In this case,
From the viewpoint of functionality of the present invention, it is desirable that the volume of the combined particles is half or less.

On the other hand, as the binder, any polymeric composition can be used without particular restrictions, but thermosetting resin compositions such as epoxy resins are preferred from the viewpoint of adhesive strength and reliability. In addition, solvent-soluble resins such as alkyd and vinyl resins for general paints can also be used as desired. Additionally, the polymeric composition may include filler materials such as insulating particles for reinforcing or bulking purposes.

The basic configuration of the present invention, its characteristic physical properties, effects in typical usage examples, detailed configuration and its significance have been explained above.
These descriptions are not intended to limit the invention.

Example 1 A toluene solution of 0.1M tetrabutoxytitanium and 0.4M triethylaluminum was cooled with dry ice methanol and poured onto a glass substrate placed horizontally in a glass container kept in vacuum.

Thereafter, acetylene gas was introduced into the glass container to obtain a polyacetylene thin film with a thickness of about 0.0 μm.

This was transferred to another glass container and doped with chlorosulfuric acid in the gas phase. Next, the mixture was pulverized to submicron size using a freezer mill while cooling with liquid nitrogen to prepare synthetic metal particles.

80 parts by volume of this fine powder and 20 parts by volume of an epoxy resin (Epicoat 82B manufactured by Shell) were thoroughly kneaded, and 2 parts by volume of triethylenetetramite as a hardening agent was kneaded therein to obtain an adhesive.

Apply this adhesive to a thickness of about 10 μm on the copper plate surface and
After curing with C for about 40 minutes, a metal mask with a pitch of 100 μm and a line width of 6 μm was placed thereon, and a xenon flash light of 10 Joules/crl was irradiated thereon.

When the resistance of each part was measured with a microprobe, the non-irradiated part had a value of 5 ohms and the irradiated part had a value of 2 ohms, confirming an irreversible change in conductivity.

Example 2 A pair of glass plate electrodes coated with gold were inserted into each of the electrolyte solutions listed in the following table, and thiophene, 3-methylthiophene, and virol were electrolytically polymerized by applying current for 1111 mm and 74 mm for 80 minutes. each about 20 μm thick on gold electrodes,
Polythenylene, poly(3-methylthennylene) and polypyrrole thin films were obtained.

During electrolytic polymerization, the anion portion of the supporting electrolyte shown in the table is incorporated into the polymer as an impurity, so the thin film becomes a synthetic metal.

Composition of Electrolyte Solution Each of these thin films was cut into pellets of about 1 ff square, and then pulverized to submicron size in a freezer mill while cooling with liquid nitrogen to prepare synthetic metal particles.

Next, an adhesive was prepared using each particle in the same manner as in Example 1, and this was applied to the surface of the copper plate to a thickness of approximately 10 μl.
It was cured at o'C for about 40 minutes.

A metal mask having a pitch of 100 μm and a line width of 50 μm was placed on this surface, and a xenon flash light of 10 joules/c11 was irradiated from above. When we measured the resistance of each part with a microprobe, the ratio (resistance of irradiated part/resistance of non-irradiated part) was:
The polythenylene was 2×10, the poly(3-methylthennylene) was 7×1o51, and the polypyrrole was 4×10′.

Effects of the Invention As described above, the present invention provides a conductive adhesive having a novel functionality in that its conductivity can be controlled by external energy, which was not present in conventional conductive adhesives.

Claims (3)

[Claims] (1) A functional conductive adhesive characterized by being made of a polymer composition containing synthetic metal particles. (2) The functional conductive adhesive according to claim 1, wherein the polymer composition contains any one of metal particles, carbon particles, and insulating particles. (3) The functional conductive adhesive according to claim 1 or 2, wherein the synthetic metal particles are conductive polymers containing impurities.