JPS58167662A - Electrically conductive adhesive - Google Patents

Abstract

PURPOSE:An electrically conductive adhesive, prepared by incorporating fine powder of titanium carbide, and titanium nitride with an adhesive, and having electric conductivity and straining effect, a low electrical resistance, high adhesive strength and good chemical stability, and capable of retaining the high adhesive force for a long term. CONSTITUTION:An electrically conductive adhesive prepared by incorporating fine powder of titanium carbide and/or titanium nitride with an adhesive, e.g. modified acrylic resin, epoxy resin or polyamide resin, preferably in 8-25% volume ratio. The shape of the fine powder is preferably of a strip or arborescence. EFFECT:High abrasion resistance suitable for use in parts causing abrasion.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a conductive adhesive obtained by mixing a conductive agent into the adhesive.

Conventional conductive adhesives are made by mixing metal powder such as copper powder, nickel powder, iron powder or silver powder, or carbon powder into an adhesive made of a synthetic resin material.

However, products that contain metal powder have the disadvantage that the synthetic resin that makes up the adhesive and the metal powder cause a chemical reaction, resulting in a shortened service life.Also, the hardness of the metal powder is low. Moreover, the strength of the solidified product after the adhesive is solidified is not sufficient, and therefore the adhesive strength is not satisfactory. on the other hand,
Products mixed with carbon powder have low electrical resistance, so
It easily generates heat, and since its hardness is still small, the strength of the solidified product is low, resulting in low adhesive strength.

In view of the above points, it is an object of the present invention to provide a conductive adhesive having a composition that has low electrical resistance and excellent adhesive strength.

The present invention uses titanium nitride (T i N) or carbide as a material for imparting conductivity, instead of conventional copper powder, nickel powder, iron powder, silver powder, carbon powder, or even silver-coated copper powder. It is constructed by using powder of one or both of titanium (T i C) and mixing it into an insulating adhesive made of synthetic resin. The specific resistance of TiN is 2
2~130μΩ・z, 'l'iCO resistivity is 70~17
It is about 3 μΩ・m, 1.6 μΩ・m for silver and 98 μΩ・m for iron.
Compared to μΩ, the specific resistance is higher, but carbon (
The resistivity is about 1/20th to 1/200th of the specific resistance (4000 μΩ·m), and the resistance value is an order of magnitude smaller. Furthermore, when comparing the hardness using Vickers hardness, the hardness of silver, iron, copper, etc. is about 100 to 300 kfl/-, while that of TiN is 1800 to 21-00 kg/ml.
t, TiC is about 2900 to 3200 kg/- and has a hardness of about 100 lbs. Therefore, if a mixture of TiN or Tic fine powder is used in an adhesive, compared to the conventional mixture of carbon powder, heat generation due to high electrical resistance can be prevented, and the adhesive strength due to heat generation can be reduced. (Synthetic resins used as adhesives tend to soften and reduce adhesive strength due to temperature rises.) In addition, since the hardness of the conductive agent is low, the hardness and resistance of the solidified adhesive will be reduced. Since it is abrasive, it can have a long life when used in places that are subject to friction.

In addition, since the hardness of the conductive material is 100%, the adhesive force is 0.000%. The reason why the adhesive strength increases as the hardness increases is considered to be as follows. something (adhesive) is applied to something (solid) (must be wet), and then the object (adhesive) is applied after it is pasted together.
This is done by solidifying (becoming solid),
Since adhesion is not a chemical bond, there is a type of surface tension that overcomes the affinity when the adhesive becomes a solid, an attractive force due to polarization between the solid and the adhesive, and the degree of strength of the solidified adhesive as a solid. It is thought that it depends on TiN and T.
Because the hard particles of iC are mixed in, they exist as foreign substances in the adhesive, and when the adhesive hardens into a solid, the solidified solid is hard, abrasion resistant, and strong. It is thought that this creates and remains strain in the solid agent, increasing the strength of the solidified product as a solid, and that this contributes in some way to strengthening the adhesive force. If the conductive material to be mixed is conventionally metal powder such as copper or nickel or carbon powder, which has low hardness, the metal powder may be deformed by the deformation force generated when the adhesive solidifies. However, when a conductive agent with high hardness is used as in the case of the present invention, distortion remains and the adhesive force is strengthened.

Next, examples of the present invention will be described. In the examples, Ti of 13 μΦ was added to the modified acrylic resin as the main material.
13 g (by volume) of N powder was mixed in, and an amine compound was mixed therein as a hardening agent in a volume ratio, and 5550 iron and iron were bonded together to measure the adhesive strength. In addition, for comparison, as a conventional example, an adhesive was made using iron powder of the same diameter instead of TiN powder and using the same main agent and hardening agent.
A similar test was conducted. The test results are shown in the drawing.

As shown in the figure, in the range of -20° C. to 100° C., greater adhesive strength was obtained in the case of the present invention than in the case of the conventional example.

Furthermore, by applying 32KHz ultrasonic waves at 15W for bonding, even stronger adhesion was achieved. When this ultrasonic wave was used to bond Teflon with the material of the example, the adhesive force was almost zero according to the conventional example, but according to the example, the adhesive strength was about 65 kg/kg at room temperature.
An adhesive strength of ca was obtained.

Next, when TiC powder is used as the conductive agent, similar results are obtained as in the above examples, and when epoxy resin or polyamide adhesive is used as the main adhesive, the same results are obtained. was gotten.

In addition to acrylic and epoxy adhesives, phenolic adhesives,
Various materials are used, such as silicone-based, urethane-based, cyanoacrylate-based, plastisol-based, chloroprene-based, and nitrile rubber-based.

In addition, the size and amount of TiN and TiC powder to be mixed is different from that of fine powder of around several μmφ or less, as the material itself has a higher electrical resistivity than conventional metals and alloys. However, depending on the purpose, powder with a diameter of several tens of μm or more can also be used, and the amount of mixed powder is about 3 to 45% (volume ratio), preferably 8 to 25%, depending on the purpose etc. After mixing to a certain degree, the shape of the powder particles may be spherical or close to spherical, but it is also possible to form them into strips, pieces, etc.
Alternatively, a dendritic one seems to be more preferable than the above-mentioned strain residual effect.

In addition, if you want to reduce the electrical resistance, do not simply increase the amount of mixing, but add an appropriate amount of copper powder, nickel powder, iron powder, silver powder, silver-coated steel, nickel, or iron powder, etc.
It is sufficient to mix it in place of iC powder, especially if it is mixed with magnetic powder.
This seems to be effective in increasing the weighting effect.

As described above, in the present invention, since TiN1 or Tic is used as the material imparting conductivity, it has good chemical stability and can maintain high adhesive strength over a long period of time. However, since TjN and TiC have sufficiently low electrical resistance, they prevent heat generation when energized, prevent deterioration due to use, and have good chemical stability, allowing them to have a long life. Can be done.

Furthermore, since TIN and TiC have moderate hardness, they can obtain a large adhesive force due to the heating effect, and have high abrasion resistance, so they are suitable for use in areas where friction occurs.

[Brief explanation of the drawing]

The drawing is a diagram showing the adhesive strength of the present invention and a conventional example in comparison with temperature as a parameter. Patent applicant Agent: Inoue Japax Institute Co., Ltd.
Young Patent Attorney 1) Katsu - 403

Claims (1)

[Claims] 1. A conductive adhesive characterized in that fine powder of one or both of titanium carbide and titanium nitride is mixed into the adhesive to impart conductivity and a weighting effect.