An anisotropic adhesive for bonding electrical components

Claim 2

An interconnection of two electrical circuit components including: a first circuit component having a first surface, and a plurality of spaced apart first electrical contacts on the first surface; a second circuit component having a second surface, and a plurality of spaced apart second electrical contacts on the second surface; and a connecting means for joining said first and second circuit components with said first and second surfaces facing one another and spaced apart from one another, and with at least selected ones of said second contacts aligned with associated first contacts to form pairs of opposed first and second contacts; wherein said connecting means includes a dielectric medium between and contiguous with said first and second surfaces, and a plurality of fusible, electrically conductive particles dispersed substantially uniformly throughout said medium; a portion of said particles forming particle sets, with the particles in each set being at least substantially aligned with an associated contact pair, and fused to form a mechanical and electrical connection between the first and second contacts of said associated contact pair.

Claim 3

The interconnection of Claim 1 wherein: said medium comprises an adhesive resin, and cooperates with said connections between the contacts of each associated contact pair to provide the mechanical bond between said first and second components.

Claim 4

The interconnection of Claim 2 wherein: said resin is a polyester resin.

Claim 5

The interconnection of Claim 1 wherein the mechanical bond of said first and second components is provided substantially by said connections between the contacts of said associated contact pairs.

Claim 6

The interconnection of Claim 1 wherein: said particles not included in said sets are substantially spherical and electrically isolated from one another by said medium.

Claim 7

The interconnection of Claim 5 wherein: said particles not included in said sets are substantially similar in size, and have a diameter of less than 44 microns.

Claim 8

The interconnection of Claim 1 wherein: said particles consist essentially of an alloy including at least one of the following tin, lead, bismuth, indium and cadmium.

Claim 9

The interconnection of Claim 7 wherein: said alloy is a eutectic alloy.

Claim 10

An interconnection of two electric circuit components including: a first circuit component having a first surface and a plurality of spaced apart first electrical contacts on said first surface; an interconnecting layer on said first surface and formed from a liquid mixture including a dielectric medium, a plurality of fusible, electrically conductive particles dispersed substantially uniformly throughout said medium, and a solvent, said mixture applied to said first surface and cured to form said interconnecting layer, said layer including said medium and a substantially uniform dispersion of said particles, in spaced apart relation, throughout said medium; a second circuit component having a second surface and a plurality of second spaced apart electrical contacts on said second surface, said second surface facing said first surface, contiguous with said inter­connecting layer, and with at least selected ones of said second contacts aligned with associated first contacts to form pairs of opposed first and second contacts; and wherein a portion of said particles form discrete sets of particles, each set consisting of particles at least substantially aligned between an associated pair of said first and second contacts, and fused to form a mechanical and electrical connection between said associated pair of contacts.

Claim 11

An interconnection of two electric circuit components including: a first circuit component having a first surface and a plurality of spaced apart first electrical contacts on said first surface; an interconnecting layer on said first surface and formed from a liquid mixture including a dielectric medium, a plurality of fusible, electrically conductive particles dispersed substantially uniformly throughout said medium, and a solvent, said mixture applied to said first surface and cured to form said interconnecting layer, said layer including said medium and a substantially uniform dispersion of said particles, in spaced apart relation, throughout said medium; a second circuit component having a second surface and a plurality of second spaced apart electrical contacts on said second surface, said second surface facing said first surface, contiguous with said inter­connecting layer, and with at least selected ones of said second contacts aligned with associated first contacts to form pairs of opposed first and second contacts; and wherein a portion of said particles form discrete sets of particles, each set consisting of particles at least substantially aligned between an associated pair of said first and second contacts, and fused to form a mechanical and electrical connection between said associated pair of contacts.

Claim 12

The interconnection of Claim 1 wherein: said particles comprise from ten to fifty percent, by weight, of said connecting layer.

Claim 13

The interconnection of Claim 1 including: a plurality of non-fusible, electrically insulative particles smaller in diameter than said electrically conductive particles, dispersed substantially uniformly throughout said medium.

Claim 14

The interconnection of Claim 11 wherein: the diameter of said electrically insulative particles is substantially equal to the distance between the first and second contacts of each said pair.

Claim 15

The interconnection of Claim 9 wherein: said solvent comprises up to fifty percent, by weight, of said liquid mixture.

Claim 16

The interconnection of Claim 9 wherein: said solvent consists essentially of methylene chloride.

Claim 17

The interconnection of Claim 9 wherein: said liquid mixture further includes a plurality of substantially non-fusible, electrically non-conductive particles dispersed substantially uniformly throughout said medium and substantially smaller in diameter than said electrically conductive particles.

Claim 18

A process for connecting first and second electrical circuit components, including the steps of: (a) forming an interconnecting mixture including a dielectric medium, a plurality of fusible, electrically conductive particles dispersed substantially uniformly throughout said medium, and a solvent; (b) applying said interconnecting mixture over a first surface of a first circuit component, thereby to cover a plurality of spaced apart first electrical terminals on said first surface; (c) drying said mixture to form an interconnecting layer including said particles dispersed substantially uniformly and in spaced apart relation in said medium; (d) providing a second circuit component having a second surface and a plurality of spaced apart second electrical terminals on said second surface, and maintaining said second surface against said inter­connecting layer and facing said first surface, while aligning at least selected ones of said second terminals with associated first terminals to form pairs of opposed first and second terminals; (e) increasing the temperature of said inter­connecting layer a first value to deform said medium whereby individual sets of said conductive particles, each set consisting of particles at least substantially aligned between an associated pair of said first and second terminals, contact the terminals of their associated terminal pairs; and (f) further increasing the temperature of said interconnecting layer to a second value greater than said first value, to melt said conductive particles and thereby fuse each of said sets into a mechanical and electrical connection between its associated first and second electrical terminals.

Claim 19

A process for connecting first and second electrical circuit components, including the steps of: (a) forming an interconnecting mixture including a dielectric medium, a plurality of fusible, electrically conductive particles dispersed substantially uniformly throughout said medium, and a solvent; (b) applying said interconnecting mixture over a first surface of a first circuit component, thereby to cover a plurality of spaced apart first electrical terminals on said first surface; (c) drying said mixture to form an interconnecting layer including said particles dispersed substantially uniformly and in spaced apart relation in said medium; (d) providing a second circuit component having a second surface and a plurality of spaced apart second electrical terminals on said second surface, and maintaining said second surface against said inter­connecting layer and facing said first surface, while aligning at least selected ones of said second terminals with associated first terminals to form pairs of opposed first and second terminals; (e) increasing the temperature of said inter­connecting layer a first value to deform said medium whereby individual sets of said conductive particles, each set consisting of particles at least substantially aligned between an associated pair of said first and second terminals, contact the terminals of their associated terminal pairs; and (f) further increasing the temperature of said interconnecting layer to a second value greater than said first value, to melt said conductive particles and thereby fuse each of said sets into a mechanical and electrical connection between its associated first and second electrical terminals.

Claim 20

The process of Claim 16 wherein: the step of applying said interconnecting mixture over a first surface of a first circuit device includes the steps of: (a) applying said mixture in liquid form to a release-coated transfer sheet; (b) drying said mixture to form said interconnecting layer on said transfer sheet; (c) pressing said layer and transfer sheet against said first surface, with said interconnecting layer contiguous with said first surface, and applying heat to said interconnecting layer and transfer sheet; and (d) removing said transfer sheet from said inter­connecting layer.

Claim 21

The process of Claim 16 wherein: the step of applying heat to said interconnecting layer to raise its temperature to a first value further includes the step of simultaneously applying a selected pressure against said second component to controllably urge said second surface against said interconnecting layer.

Claim 22

The process of Claim 18 wherein: said first electrical component includes flexible tape circuitry, and said second electrical component includes an integrated circuit chip positioned above said circuitry; said heat being applied from below said circuitry, while said pressure is applied from above said chip.

Claim 23

The process of Claim 16, including: the further step of performing an electrical test on said electrical components following the step of increasing the temperature of said interconnecting layer to said first value, and before the step of further increasing the temperature of said interconnecting layer to said second value.

Claim 24

The process of Claim 16 wherein: said solvent is a polar solvent.

Claim 25

The process of Claim 21 wherein: said solent consists essentially of methylene chloride.

Claim 26

The process of Claim 16 wherein: said medium is a resin wuith heat-activated adhesive properties.

Claim 27

The process of Claim 16 wherein: said solvent includes up to fifty percent, by weight, of said mixture, and wherein said particles, after the curing of said mixture, comprise from ten to fifty percent, by weight, of said interconnecting layer.

Claim 28

The process of Claim 16 wherein: said interconnecting mixture further includes a plurality of non-fusible, electrically non-conductive particles smaller in diameter than said conductive particles and dispersed substantially uniformly throughout said dielectric medium.

Claim 29

The process of Claim 25 wherein: the step of applying heat to said interconnecting layer to raise its temperature to a first value, and the step of further increasing the temperature of said inter­connecting layer to said second value, further include the step of simultaneously applying pressure against said secnd component to controllably urge said second surface against said interconnecting layer; wherein pluralities of said non-conductive particles, positioned between said pairs of first and second terminals, limit travel of the terminals of each said pair towards one another responsive to said pressure.

Claim 30

An anisotropic adhesive for connecting electrical circuit components, including: a thin dielectric film; and a plurality of fusible electrically conductive particles dispersed substantially uniformly throughout said medium, substantially uniform in diameter, and spaced apart from one another; and wherein at least some of said fusible particles are comprised of particle sets, with the particles in each set being fused and in contact with an associated first terminal of a first electrical circuit component, and an associated second terminal of a second electrical circuit component.

Claim 31

An anisotropic adhesive for connecting electrical circuit components, including: a thin dielectric film; and a plurality of fusible electrically conductive particles dispersed substantially uniformly throughout said medium, substantially uniform in diameter, and spaced apart from one another; and wherein at least some of said fusible particles are comprised of particle sets, with the particles in each set being fused and in contact with an associated first terminal of a first electrical circuit component, and an associated second terminal of a second electrical circuit component.

Claim 32

The anisotropic adhesive of Claim 27 further including: a plurality of non-fusible, electrically insulative particles dispersed substantially uniformly throughout said medium and having a diameter less than that of said conductive particles.

Claim 33

The adhesive of Claim 27 further including: a plurality of non-fusible, electrically insulative particles dispersed substantially uniformly throughout said medium and having a diameter less than that of said conductive particles, with certain particles of said plurality of said non-fusible particles in contact with said first and second terminals, thereby to determine a spacing between said first and second terminals in accordance with the diameter of said certain particles.