Polymer particles, conductive particles, and an anisotropic conductive packaging materials containing the same
Disclosed herein are anisotropic conductive particles contained in anisotropic conductive adhesive films which can be used in circuit board mounting applications. The conductive particles have a uniform shape, a narrow particle diameter distribution, and appropriate compressive de-formability and recoverability from deformation. In addition, the conductive particles exhibit enhanced conducting properties without being ruptured when interposed and compressed between connection substrates, thereby achieving a sufficient contact area between the particles and the connection substrates. Further disclosed are polymer-based particles used in the conductive particles.
1. A polymer particle for anisotropic conductive packaging materials prepared by copolymerizing a styrene-based monomer, acrylonitrile, or a combination thereof with at least one crosslinking polymerizable monomer selected from the group consisting of divinylbenzene, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, divinylsulfone, allyl compound, (poly)alkylene glycol di(meth)acrylate, pentaerythritol (meth)acrylate, methylolpropane (meth)acrylate, glycerol tri(meth)acrylate, and mixtures thereof, wherein said polymer particle has a K value at 10% particle diameter deformation (10% K value) of about 250 to about 700 kgf/mm 2 , a compression recovery factor of less than 30%, and a compressive rupture deformation of about 30% or higher, wherein the polymer particle has a 20% K value (K value at 20% compressive deformation and a 30% K value (K value at 30% compressive deformation) not higher than about 70% of the 10% K value.
2. The polymer particle according to claim 1 , wherein the polymer particle has a 10% K value of about 350 to about 600 kgf/mm 2 .
3. The polymer particle according to claim 1 , wherein the polymer particle has an average particle diameter of about 0.1 to about 200 μm.
4. The polymer particle according to claim 1 , wherein the polymer particle has an aspect ratio lower than about 1.5 and a coefficient of variation (CV) not higher than about 20%.
5. The polymer particle of claim 1 , wherein said allyl compound comprises at least one compound selected from the group consisting divinylbenzene, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, allyl (meth)acrylate, divinylsulfone, diallyl phthalate, diallylacrylamide, triallyl (iso)cyanurate, triallyl trimellitate, and mixtures thereof.
6. The polymer particle of claim 1 , wherein said (poly)alkylene glycol di(meth)acrylate comprises at least one compound selected from the group consisting of (poly)ethylene glycol di(meth)acrylate, (poly)propylene glycol di(meth)acrylate, and mixtures thereof.
7. The polymer particle of claim 1 , wherein said pentaerythritol (meth)acrylate comprises at least one compound selected from the group consisting of pentaerythritol tetra(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol di(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, and mixtures thereof.
8. The polymer particle of claim 1 , wherein said methylolpropane (meth)acrylate comprises at least one compound selected from the group consisting of trimethylolpropane tri(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, tetramethylolpropane tetra(meth)acrylate, and mixtures thereof.
9. The polymer particle according to claim 1 , wherein the styrene-based monomer comprises at least one monomer selected from the group consisting of styrene, ethyl vinyl benzene, α-methyl styrene, m-chloromethyl styrene, and mixtures thereof.
10. The polymer particle according to claim 1 , wherein the polymer particle is prepared by seeded polymerization using a polymer seed particle having a molecular weight of from about 1,000 to about 30,000.
11. The polymer particle according to claim 10 , wherein the total content of the polymerizable monomer used in the seeded polymerization is about 10 to about 300 parts by weight, based on one part by weight of the polymer seed particle.
12. A conductive particle comprising the polymer particle according to claim 1 , and at least one conductive metal layer formed on the surface of the polymer particle.
13. An anisotropic conductive packaging material comprising the conductive particle according to claim 12 comprising the polymer particle and at least one conductive metal layer formed on the surface of the polymer particle.
14. The polymer particle according to claim 1 , having a compression recovery factor of 24% or less.
15. The polymer particle according to claim 1 , comprising a polymer comprising of from 10 to 20 parts crosslinking polymerizable monomer and from 80 to 90 parts polymerizable unsaturated monomer.