Compound wherein conductive circuits can be made

Abstract

To improve the characteristics of a compound adapted to create inside an electrically conductive track or area, the compound comprising a solvent, a polymer with double covalent conjugate bond, namely a heterocyclic compound formed by n carbon atoms and one atom of a different type linked in a ring structure; and a dispersion of conductive particles, there is added an agent adapted to slow down the precipitation of the conductive particles within the material.

Claims

1. A compound material suitable for creating an electrically conductive track or area inside the material, comprising: a solvent, a polymer with double covalent conjugate bond, a dispersion of conductive particles, and an agent adapted to slow down precipitation of the conductive particles within the material, wherein said agent comprises a mineral resin.

2. The material according to claim 1, wherein said agent comprises silicone.

3. The material according to claim 1, wherein said agent comprises said polymer.

4. The material according to claim 3, wherein said polymer comprises a polythiophene.

5. The material according to claim 1, wherein a size of gaps in a lattice formed by the polymer and/or a maximum distance between branches of the polymer is at most 400 nm.

6. The material according to claim 5, wherein the size of the gaps in the lattice formed by the polymer and/or the maximum distance between its branches is at most 100 nm.

7. The material according to claim 5, wherein the size of the gaps in the lattice formed by the polymer and/or the maximum distance between its branches is less than or equal to 50 nm.

8. The material according to claim 5, wherein the size of the gaps in the lattice formed by the polymer and/or the maximum distance between its branches is less than or equal to 40 nm.

9. The material according to claim 1, wherein the polymer with double covalent conjugate bond comprises a heterocyclic compound formed by n carbon atoms and one atom of a different type linked in a ring structure.

10. A method for maintaining a dispersion of conductive particles within, and at a certain distance from borders, of a compound material suitable for creating an electrically conductive track or area inside the material, the material further comprising: a solvent, and a polymer with double covalent conjugate bond, wherein the method comprises slowing down precipitation of the conductive particles within the material with an agent comprising a mineral resin while the material solidifies.

11. The method according to claim 10, wherein the precipitation is slowed down by means of silicone.

12. The method according to claim 10, wherein the precipitation is slowed down due to a density of the polymer and/ or a proximity of its molecular chains.

13. The method according to claim 10, wherein the polymer with double covalent conjugate bond comprises a heterocyclic compound formed by n carbon atoms and one atom of a different type linked in a ring structure.

Description

(1) The preparation described here has the object to reduce the dimensions of such gaps (e.g. the diameter or the maximum size and/or the maximum distance between the branchings of the polymer) to a maximum of 400 nm, a value at which the described effect of particle suspension manifests.

(2) Even better results are obtained if such gaps or distances have dimensions less than 100 nm, preferably equal to or less than 40-50 nm. In fact, the particles can have a size distributed statistically in a range of values, therefore the percentage of smaller particles could pass through the polymer chains.

(3) The smaller the size of the gaps or the distance between branches, the lesser the percentage of particles passing through the polymer lattice.

(4) Another agent can be a resin, e.g. an organic-mineral resin. An example of resin is the PET plus calcium.

(5) The choice of the type of electromagnetic stimulus to be used on the polymer is important as too bland a stimulus is not sufficient to break the carbon-sulfur bonds, while too energetic a stimulus gives rise to a form of pyrolysis which leads to an insulating material. The preferred laser to strike the PATAC is a laser with wavelength of 488 nm.

(6) Preferably the PATAC in the compound is used only as amalgam for the components, and not to create polymeric conductive chains, as instead the Thiophene or P.sub.3HT do. The PATAC is burned by the passage of the laser.

(7) The compound can be applied in liquid or gelled form directly on a support or applied via a separate film or layer of rigid or flexible support.

(8) The conductivity of the compound is improved—as mentioned—by the presence of the aggregants or the conductive particles, such as Ag, Ni, St, Au or Pt.

(9) The silver, or one of Ni, St, Au or Pt, has given excellent results of conductivity. The silver particles, initially isolated from the polymer, stick to one another when the PATAC or Thiophene or carbon-based polymer in the compound is struck by the laser, and in the compound a chain of conductive particles in contact with each other is created.

(10) With the same object of operation, compounds can be added such as carbon black, and/or components of carbon black and/or carbon nanotubes.

(11) The compound enables to exploit its electrical peculiarities also for the generation of electrical power or mechanical vibrations, see below.

(12) In the solvent there can be present metal oxides, and/or a further component such as a graphite or graphene, excellent dopants, primarily for their high electrical conductivity.

(13) The metal oxides can be added with ferric chloride or aluminum chloride, with or without coloring pigments.

(14) The metal oxides can for example be constituted of iron oxides in the formulation Fe.sub.2O.sub.3, or Fe.sub.3O.sub.4 or even better, for their better magnetization/saturation curve, of chromium oxides or dioxides, in the formulation CrO.sub.2.

(15) With a laser, or other electromagnetic radiation, the compound is struck to energize or de-energize the molecules of Thiophene by sending the right energy. When they are excited, their electronic state changes and they become conductive. A subsequent radiation pours energy on the excited molecule and returns it to the original electronic configuration, that is an insulator.

(16) In particular, the laser radiation breaks down in the Thiophene the binding of the radical containing sulfur, leaving the polymeric chains in mutual electronic and conductive contact through the free orbital. A subsequent radiation restores the link with the free radical and/or cuts out again the Thiophenic chains, and the compound turns back insulator at that spot.

(17) Clearly, by the Laser one can create tracks or conductive areas in the compound at will.

(18) In particular, the compound can be loaded with a quartz-based filler (one or more of its 19 families), in particular BaTiO.sub.3 or PbTiO.sub.3. A component with TiO.sub.3 has the advantage of being very gripping, not dry and has the possibility with low energy to make electrons available.

(19) In the compound there is preferably dispersed quartz with different particle sizes, both for conveying charges toward the polymer, and as a voltage/current generator via piezoelectric effect.

(20) In fact, a pressure by an object on the compound generates in the quartz a discharge or a current pulse. By pressing and releasing periodically the compound one can generate a pulsating current. This current can be collected e.g. by one or more tracks of PATAC or Thiophene made conductive.

(21) Another surprising consequence is that one can draw at will on the paint (through polarization) some vibration-generating areas. Alternatively, or in addition, one can activate the vibration in areas picked at will having at disposal an electrical excitation for the quartz.

(22) The problem of preventing short-circuits described above is equally solved by the method as generally defined in claim 6, which allows to limit the speed and/or the number of particles that precipitate in the material. Advantageous variants of the method are defined in the dependent claims.

(23) In general, a compound such as that described can also operate as a sensor, e.g. to measure the mechanical stress (tension or compression) to which a surface is subjected, as a strain-gauge.

(24) By drawing a conductive path in the material deposited on a surface, it has been observed experimentally that the trend of its resistance value is linear when the elongation varies. In particular, a surface coated with the above material, if subjected to a load (tensile or compressive), varies its electrical resistance compared to the value at rest (no load).

(25) At the disappearance of the load, the resistance of the material returns to its rest value.

(26) E.g. a sample of 10 cm on a support of polyacetal (1 cm×10 cm) subjected to 1 Kg, varies its resistance by 10Ω compared to its rest value without load being about 160Ω.

(27) Obviously, the linearity in the resistance variation of the material depends on the stretching or compression linearity of the support. The molecular chains of the material, e.g. the PATAC or Thiophene, within certain limits stretch with linearity and return to the rest, unloaded point.