US 5,769,996 A · Compositions and methods for providing anisotropic conductive pathways and bonds between two sets of conductors

Abstract

The invention provides a composition comprising: (i) a ferrofluid comprising a colloidal suspension of ferromagnetic particles in a non-magnetic carrier liquid, and (ii) a plurality of electrically-conductive particles having substantially uniform sizes and shapes, dispersed in the ferrofluid. Various types of substantially non-magnetic electrically-conductive particles are described. Application of a substantially uniform magnetic field by magnet means to the composition causes the electrically-conductive particles to form a regular pattern. The composition is used for providing anisotropic conductive pathways between two sets of conductors in the electronics industry. The composition may be a curable adhesive composition which bonds the conductors. Alternatively or in addition the electrically-conductive particles may have a latent adhesive property e.g. the particles may be solder particles. The ferrofluid may be a colloidal suspension of ferromagnetic particles in a liquid monomer.

Claims40

Dependent claims

A method of providing anisotropic conductive pathways between two sets of conductors which comprises forming said pathways with a plurality of electrically conductive particles having substantially uniform sizes and shapes, said electrically conductive particles having been arrayed in a regular pattern by application of a substantially uniform magnetic field to a composition comprising (i) a plurality of electrically-conductive particles having substantially uniform sizes and shapes dispersed in either (ii) a ferrofluid comprising a colloidal suspension of ferromagnetic particles in a non-magnetic carrier liquid, or (iii) a mixture of a ferrofluid comprising a colloidal suspension of ferromagnetic particles in a non-magnetic carrier liquid and a curable liquid composition.

A method of making an anisotropically conductive bond between two sets of conductors, wherein a layer of adhesive composition is applied to one set of conductors and a second set of conductors is brought against the layer of adhesive composition after which the composition is cured in a composition curing step, the method characterized in that:

(a) the adhesive composition comprises (i) a plurality of electrically-conductive particles having substantially uniform sizes and shapes dispersed in either (ii) a ferrofluid comprising a colloidal suspension of ferromagnetic particles in a curable adhesive non-magnetic carrier liquid, or (iii) a mixture of a ferrofluid comprising a colloidal suspension of ferromagnetic particles in a curable or non-curable, magnetic carrier liquid and a curable adhesive liquid composition;
and
(b) the method further comprises:
exposing the layer of adhesive composition to a substantially uniform magnetic field such that interaction between the ferrofluid and the electrically-conductive particles causes the electrically-conductive particles to form a regular pattern of particles each in electrical contact with an adjacent particle and/or with a conductor in one or both sets of conductors or with both a particle and one or two conductors, whereby conductive pathways are provided from one set of conductors to the other set, each pathway comprising one or more of the electrically-conductive particles, before the adhesive composition is cured;
and
the composition curing step is performed while the electrically conductive particles are formed into said pattern so as to lock the pattern in position.

3 more elements

A method of making an anisotropically conductive bond between two sets of conductors wherein a layer of a composition comprising particles with a latent adhesive property is applied to one set of conductors and a second set of conductors is brought against the layer of the composition after which the latent adhesive property of the particles is activated, the method characterized in that:

(a) the particles with a latent adhesive property are electrically-conductive particles having substantially uniform sizes and shapes;
(b) the composition comprises (i) a plurality of said particles with a latent adhesive property dispersed in either (ii) a ferrofluid comprising a colloidal suspension of ferromagnetic particles in a non-magnetic carrier liquid or (iii) a mixture of a ferrofluid comprising a colloidal suspension of ferromagnetic particles in a non-magnetic carrier liquid and a curable liquid composition;
and
(c) the method further comprises:
exposing the layer of the composition to a substantially uniform magnetic field such that interaction between the ferrofluid and the electrically-conductive particles causes the electrically-conductive particles to form a regular pattern of particles each in contact with an adjacent particle with a conductor of one or both sets of conductors or with both a particle and one or two conductors;
and
activating the latent adhesive property of the particles with a latent adhesive property whereby conductive pathways are provided from one set of conductors to the other set, each pathway comprising one or more of the electrically-conductive particles, and the conductors are bonded by the particles.

4 more elements

Dependencies are inferred from the claim text.

Compositions and methods for providing anisotropic conductive pathways and bonds between two sets of conductors

Life of this patent

Compositions and methods for providing anisotropic conductive pathways and bonds between two sets of conductors

Life of this patent

Abstract

Claims40