Anisotropic conductive sheet
View Patent ↗Disclosed herein is an anisotropically conductive sheet capable of holding charge in its surfaces under an unpressurised state, and moving the charge held in the surface in a thickness-wise direction thereof in a state pressurised in the thickness-wise direction, thereby controlling the quantity of the charge at the surface. This anisotropically conductive sheet comprises a sheet base composed of an elastomer and conductive particles exhibiting magnetism contained in the sheet base in a state oriented so as to arrange in rows in a thickness-wise direction of the sheet base, and dispersed in a plane direction thereof. Supposing that a volume resistivity in the thickness-wise direction under an unpressurised state is R 0 , and a volume resistivity in the thickness-wise direction in a state pressurised under a pressure of 1 g/mm 2 in the thickness-wise direction is R 1 , the volume resistivity R 1 is 1×10 7 to 1×10 12 Ω·m, and a ratio (R 0 /R 1 ) of the volume resistivity R 0 to the volume resistivity R 1 is 1×10 1 to 1×10 4 .
1. An anisotropically conductive sheet, comprising:
a sheet base comprising an elastomer; and
conductive particles exhibiting magnetism, said conductive particles being contained in the sheet base in a state oriented so as to arrange in rows in a thickness-wise direction of the sheet base, and dispersed in a plane direction of the base sheet,
wherein
supposing that a volume resistivity in the thickness-wise direction of said base sheet under an underpressurized state is R 0 , and a volume resistivity in the thickness-wise direction in a state pressurized under a pressure of 1 g/mm 2 in the thickness-wise direction is R 1 ,
the volume resistivity R 1 is 1×10 7 to 1×10 12 Ω·m, and
a ratio (R 0 /R 1 ) of the volume resistivity R 0 to the volume resistivity R 1 is 1×10 1 to 1×10 4 .
2. The anisotropically conductive sheet according to claim 1 , wherein the volume resistivity R 0 is 1×10 9 to 1×10 14 Ω·m.
3. The anisotropically conductive sheet according to claim 1 , wherein a surface resistivity is 1×10 13 to 1×10 16 Ω/□.
4. The anisotropically conductive sheet according to claim 1 , wherein a total area proportion occupied by a substance forming the conductive particles detected by electronic probe microanalysis in one surface of the sheet is 15 to 60%.
5. An anisotropically conductive sheet, comprising:
a sheet base comprising an elastomer; and
conductive particles exhibiting magnetism and a volume resistivity of 1×10 2 to 1×10 7 Ω·m, said conductive particles being contained in the sheet base in a state oriented so as to arrange in rows in a thickness-wise direction of the sheet base, and dispersed in a plane direction of said base sheet.
6. The anisotropically conductive sheet according to claim 5 , wherein the conductive particles comprise ferrite.
7. The anisotropically conductive sheet according to claim 5 , wherein, a non-magnetic conductivity-imparting substance is contained in the sheet base.
8. The anisotropically conductive sheet according to claim 1 , wherein said elastomer is cross-linked.
9. The anisotropically conductive sheet according to claim 1 , wherein said elastomer is at least one member selected from the group consisting of conjugated diene rubbers, a hydrogenated product of a conjugated diene rubber, block copolymer rubbers, a hydrogenated product of a block copolymer rubber, chloroprene rubber, urethane rubber, polyester rubber, epichlorhydrin rubber, silicone rubber, ethylene-propylene copolymer rubber, and ethylene-propylene-diene copolymer rubber.
10. The anisotropically conductive sheet according to claim 1 , wherein said elastomer is silicone rubber.
11. The anisotropically conductive sheet according to claim 1 , wherein said conductive particles comprise a ferrite represented by the formula
M 1 O.Fe 2 O 3 ,
wherein M 1 is at least one element selected from the group consisting of Mn, Fe, Ni, Cu, Zn, Mg, Co, and Li.
12. The anisotropically conductive sheet according to claim 1 , wherein said conductive particles have a number average particle diameter of from 1 to 1000 μm.
13. The anisotropically conductive sheet according to claim 1 , wherein said conductive particles have a number average particle diameter of from 1 to 20 μm.
14. The anisotropically conductive sheet according to claim 1 , wherein said conductive particles have a particle diameter distribution (Dw/Dn) of 1 to 10.
15. The anisotropically conductive sheet according to claim 1 , wherein said conductive particles have a water content of not more than 5%.
16. The anisotropically conductive sheet according to claim 5 , comprising a non-magnetic conductivity-imparting substance selected from the group consisting of a self-conductive substance, a hygroscopic conductive substance and mixtures thereof.
17. The anisotropically conductive sheet according to claim 5 , comprising an aliphatic sulfonic acid salt.
18. The anisotropically conductive sheet according to claim 5 , wherein said conductive particles comprise a ferrite represented by the formula
M 1 O.Fe 2 O 3 ,
wherein M 1 is at least one element selected from the group consisting of Mn, Fe, Ni, Cu, Zn, Mg, Co, and Li.
19. The anisotropically conductive sheet according to claim 5 , wherein said conductive particles have a number average particle diameter of from 1 to 1000 μm.
20. The anisotropically conductive sheet according to claim 5 , wherein said conductive particles have a number average particle diameter of from 1 to 20 μm.