FR2641896A1 - METHOD FOR MANUFACTURING CONDUCTIVE ANISOTROPIC MATERIAL - Google Patents

Abstract

The present invention relates to methods of making an anisotropic conductive material. The method of manufacturing an anisotropic conductive material consists in that the composition containing a dielectric and conductive particles is placed between two electrodes to which a potential difference is applied. Between the electrodes and the composition are placed electrically insulating films of a thickness preventing the access of the conductive particles to the electrodes under tension. The height of each electrode is greater than that between said electrically insulating films by at least three times. The material obtained is hardened. The method can find application in microelectronics, electronics and electrical engineering.

Description

The present invention relates to

  electronics, electronics and electrical engineering, and more particularly the manufacturing processes

  of a conductive anysotropic material.

  os05 Conductive anysotropic materials

  their application as linkers of

  Conductors on boards and turntables assembled.

  These materials contain particle chains of high electrical conductivity. he

  It is important that these chains have the same para-

  electrical meters, in other words, their conductivity must be the same, which ensures a high quality of

  conductive anysotropic materials. In addition to this,

  must have sufficient elasticity to sup-

  carry pressure and sufficiently large dimensions

of.

  The properties of anysotropic materials

  electrical conductors and their dimensions depend on their

  sensibly of the process of their manufacture.

  So, for example, we know a process of

  manufacture of an electrically conductive anysotropic material

  wherein an electrically insulating composition containing a (dielectric) polymer and conductive particles (magnetic particles, e.g., ferromagnetic particles) is placed in a magnetic field (JP, B, 60-32285). Conducting chains of magnetic particles are formed in the polymer film at locations of high intensity of the magnetic field created by the geometric configuration

  ends of the core of an electromagnet.

  The method is applicable only to the use

  magnetic particles. When carrying out this process, it is practically impossible to obtain identical parameters of the magnetic field both at

  center of the poles of the magnet that at the ends of the poles

  them, nor therefore to obtain chains with

  the same conductivity, hence the manufacture of

  insufficient conductive properties. Outraged

  this, the process requires a great consumption of energy.

  ogy. The dimensions of the material obtained are limited because it is technically impossible to achieve

  an electromagnet with ends of large poles

  dimensions while ensuring in the air gap a

their desired intensity of the field.

  There is a method of manufacturing a machine

  electrically conductive anysotropic material with

  an electric field (Journal Appl Phys Phys vol.

  , No. 4, 1968, Jones T.B., Kraybill J.P. Active Feed-

  back-control Dielectrophoretic Levitation, p. 1247-

  1252). The method consists in that a liquid dielectric with conductive particles (electrical insulating composition) is placed in a tank in

  glass installed between two electrodes. Then we ap-

  gives the electrodes a potential difference. In

  optically fixing a vertical position of the

  conductive substance or an agglomerate of these particles

  and controlling the value of the potential difference

  between the electrodes, a stable levitation of the particles in the liquid dielectric is obtained.

  which forms an anysotropic structure of the material.

  This method does not make it possible to obtain

  a large number of particle chains con-

  electricity producer because he is technically

  impossible to carry out an uninterrupted

  rights of arrangement of the chains in levitation. Or-

  This being the case, only the presence of an electric field

  re maintaining the anysotropic structure of the material

  to obtain what strongly limits the use of

obtained by this process.

  The object of the invention is to create a manufacturing process

  cation of an anysotropic material that is electrically conductive

  to obtain a material of con-

  high ductility, elasticity and sufficient dimensions.

  The problem is solved by the fact that

  a process for producing an electrically conductive anysotropic material which consists of a composition consisting of a dielectric with

  conductive particles is placed between two electro-

  to which a potential difference is applied,

  characterized in that between the electroces and the

  are placed electrical insulating films

  the thickness of which prevents access of particles

  conductors to the electrodes under tension, the height of each electrode being greater than the distance between said electrical insulating films of at least three

  time, and the resulting material is cured.

  As dielectric, it is possible to use different substances, for example paraffin,

  polymer-dielectrics capable of hardening.

  As conductive particles, one

  can use any conductive particles

  these electricity. These particles can be

  metal, for example, copper, iron,

  tone, titanium, nickel, etc., as well as non-metallic

  but covered with a layer of metal, by

  for example, glass particles coated with

  fever. Electrical insulating films may be any films used, for example, in

  HV installations. These films can be polyterated

  ethylene phthalate, polytetrafluorethylene.

  As has already been said, the height of each electrode is greater than the height between the films

  insulators three times, at least. This creates different

  your electrical voltages in the material to be obtained near the electrodes and at locations far from

  electrodes which causes the gathering of

  peripheral conductive particles close to electro-

  with formation of particle catnets

  ductrices. In order to intensify the training process

  conductive chains, the value of

  their ratio of the height of the electrode to the

  between the insulating films whose upper limit

  is determined by the possibilities of the

  tallation. Depending on the nature of the dielectric

  used, the hardening process takes place

  ently. If paraffin is used as the dielectric, the composition, before the application of the potential difference, is preheated

  up to a temperature of 60 to 70 C and hardening

  This is done by cooling the material to obtain

ne.

  When using polydimethylsilane

  loxane or epoxy resin as a dielectric, is introduced into the electrical insulating composition

  a hardener. In this case, the hardening of the material

  riau is simultaneous with its obtaining.

  Any known hardener may be used

folded for polymers.

  In some cases, it is recommended during the manufacture of the conductive anysotropic material to use at least two pairs of electrodes. This may be required when, for example, it is necessary to obtain

  an electrical coupler or couplers for two

  your drivers on the cards. To connect a larger amount of conductive tabs on the cards,

  you have to have a lot of electronic pairs

  of. The conductive anysotropic material obtained according to the proposed method comprises conductive particle chains of equal conductivity

  along all the material. The material is sufficient

  elastic and has large dimensions.

  The process for obtaining an

  sotrope driver is pretty simple technological-

  and is done in the following way.

  A composition containing a dielectric,

  conductive particles and a hardener is

  on an electrical insulating film disposed on the end faces of the lower electrodes. An insulating material, for example organic glass,

  epoxy resin, between the electrodes.

  On the upper face of the com

  position, we place another electrical insulating film.

  To prevent the flow of the composition, there is provided a chamber disposed on the lower film and

  whose height is equal to the height between.

  electrical insulating films. Above the electrical insulating film are arranged upper electrodes

  between which is also placed an insulated material

  lant. The upper and lower electrodes are

fixed.

  A difference is applied to the electrodes

  potential. At the end of the hardening of the composition

  tion, the potential difference is eliminated and

  obtains the conductive anysotropic material.

  If paraffin dielectric is used, the paraffin-containing composition and the conductive particles are first carried to a predetermined temperature. Then, the technology is the same as that described above, except that the hardening of the material obtained is by cooling. Then, we remove the difference

potential.

  To better understand the present invention,

  the following concrete examples are given below.

EXAMPLE 1

  Polymethylsiloxane is mixed with copper particles. After mixing, we introduce

  a hardener consisting of tin octoate and tetra-

  etoxysilane, and the composition obtained is placed on the

  polyethylene terephthalate electrical insulating film.

The film thickness is 16 Fm.

  On the upper surface of the composition layer, an electrical insulating film of the same thickness is placed. The height between the insulating films, electrical is 1 mmn. The composition is placed in a chamber disposed on the lower electrical insulating film. Below the bottom film and above

  of the upper film are fixed electrodes (a

  re). The height of the electrode is 6 mm. To the elec-

  trodes is applied a potential difference equal to 4 kV. After 10 minutes, the potential difference

is deleted.

  The material obtained has an electrical resistance

  that the conductive particle chain equal to 0.2 Ohm under an external mechanical pressure on the surface material (0.5 x 0.5) mm2, 0.5, N.

EXAMPLE 2

  A conductive anysotropic material is prepared according to the technology described in Example 1, except that two pairs of electrodes are used. The upper and lower electrodes arranged at a distance of

  1.25 mm from each other, are insulated by

do not epoxy.

  The material obtained has the same properties

  than that obtained according to Example 1 and can be used

  used to couple two card-carrying sections.

EXAMPLE 3

  The conductive anysotropic material is prepared according to the method described in Example 1 except that 256 pairs of electrodes are used. The distance between

  upper and lower electrodes is 1.25 mm.

  The dimensions of the obtained material are:

x 20 mm2.

EXAMPLE 4

  The conductive anysotropic material is prepared according to the method described in Example 1, except that the height of the electrodes is 3 mm and

  256 pairs of electrodes. The distance between electro-

  upper and lower is 1.25 mm.

  The material obtained has a resistance of the conductive particle chain equal to 0.8 Ohm

  under mechanical pressure on the material of an over-

  face of (0.5 x 0.5) mm2 with a force of 0.5 N.

EXAMPLE 5

  The conductive anysotropic material is prepared according to the method described in Example 1, except that

  uses as conductive particles

iron cules.

  The electrical resistance of the cha-net of conductive particles of the material obtained is

1.2 Ohm.

EXAMPLE 6

  The conductive anysotropic material is prepared according to the method described in Example 1 except that the iron-conducting particles are used and the

  height of each electrode is 3 mm.

  The electrical resistance of the conductive particle chain of the material obtained is

6 Ohm.

EXAMPLE 7

  The conductive anysotropic material is prepared according to the method described in Example 1, except that the epoxy resin is used as the dielectric and the

  hardener is polyethylenepolyamine.

  The electrical resistance of the conductive particle chain of the material obtained is

0.5 Ohm.

EXAMPLE 8

  Paraffin is brought to a temperature of 60 ° C. and conductive particles are added thereto.

  brass. From the composition obtained, it is manufactured

  that a conductive anysotropic material according to the

  described in Example 1 except that hardening

  material is air-cooled. Ensui-

  you remove the potential difference.

  The electrical resistance of the conductive particle chain of the material obtained is

1.4 Ohm.

Claims (4)

  1. A method of manufacturing an   conductive sotrope which consists of   containing a dielectric and   conductors is placed between two electrodes to which a potential difference is applied, characterized in that between the electrodes and the composition are placed electrical insulating films of a thickness which prevent access of the conductive particles to   electrodes under tension, the height of each electro-   being greater than that between said insulating films   three times at least, and the material obtained by being hardened.   2. The process according to claim 1, wherein   in that at least two pairs of electrodes are used. 3. Method according to claim 1 or 2,   characterized in that in case of use of the   refined as a dielectric, the composition is   brought to a temperature of 60 to 70 C before the application   cation of the potential difference and the hardening   the material to be obtained is cooled   is lying. 4. Method according to claim 1 or 2,   characterized in that when using the polydimed   thylsyloxane or epoxy resin as a dielec-   In this case, a hardener is   the electrical insulating composition.