High conductivity, high strength, lead-free, low cost, electrically conducting materials and applications
First Claim
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1. A lead-free electrically conductive adhesive paste composition comprising:
- a network of interconnected particles having spaces there-between;
each of said particles has a coating thereon of a fusible material;
adjacent particles in said network are isotropically adhered together through said fusible material, said spaces containing a polymer selected from the group consisting of a thermoplastic phenoxy polymer and a styrene allyl alcohol resin.
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Abstract
A structure and method of fabrication are described. The structure is a combination of a polymeric material and particles, e.g. Cu, having an electrically conductive coating, e.g. Sn. Heat is applied to fuse the coating of adjacent particles. The polymeric material is a thermoplastic phenoxy polymer or a styrene allyl alcohol resin. The structure is disposed between two electrically conductive surfaces, e.g. chip and substrate pads, to provide electrical interconnection and adhesion between their pads.
94 Citations
10 Claims
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1. A lead-free electrically conductive adhesive paste composition comprising:
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a network of interconnected particles having spaces there-between;
each of said particles has a coating thereon of a fusible material;
adjacent particles in said network are isotropically adhered together through said fusible material, said spaces containing a polymer selected from the group consisting of a thermoplastic phenoxy polymer and a styrene allyl alcohol resin. - View Dependent Claims (8, 9, 10)
or 0. where R2 and R3 are any organic group where R4 is H or any organic radical.
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9. The electrically conductive adhesive past composition according to claims 8, wherein said phenoxy polymer has structural formula:
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n>
1,m=0 or 1 Ro is or —
O—
where R2 and R3 are any organic group.
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10. The electrically conductive adhesive past composition of claim 9 wherein 100,000>
- m>
200 and R2 and R3 are selected from the group consisting of H, CH3, C3 H2s+1, CF3 where S≧
1, preferably 6≧
S≧
1 where R4 is H or any organic radical.
- m>
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2. A lead free electrically conductive adhesive paste composition comprising:
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between about 30% and 90% by weight of the composition of a plurality of particles selected from the group consisting of Cu, Au, Al, Ag, Pd and Pt in a polymer selected from the group consisting of one or more of a thermoplastic phenoxy polymer and a styrene allyl alcohol resin;
each of said plurality of particles has an isotropic electrically conductive coating selected from the group consisting of Sn, Zn, In, Bi, Pb and Sb;
at least some of said particles are fused to other said particles through said electrically conductive coating.- View Dependent Claims (3)
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4. A lead free electrically conductive adhesive paste composition comprising:
particles of copper having a fusible isotropic coating selected from the group consisting of Sn, and In, said particles are contained within a thermoplastic polymer selected from the group consisting of a thermoplastic phenoxy polymer and a styrene allyl alcohol resin, and a solvent.
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5. A lead-free electrically conductive adhesive paste composition comprising:
copper powder coated with a layer of isotropically fusible material selected from the group consisting of Sn, In, Bi, Sb, and combinations thereof in a polymer selected from the group consisting of a thermoplastic phenoxy polymer and a styrene allyl alcohol resin, said coated copper powder being mixed with a fluxing agent in said polymer. - View Dependent Claims (6, 7)
Specification