Filled epoxy compositions

Abstract

Epoxy compositions exhibiting low viscosity in the uncured state and low coefficient of thermal expansion in the cured state are provided. Also provided are processes for making the epoxy compositions. The low dielectric constant compositions are well-suited for use in multi-layer printed circuit boards. The desired properties are achieved by employment of a bimodal distribution of nano-scale fillers in the epoxy compositions.

Description

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 represents a finished electronic component, including an IC chip mounted upon a multilayer circuit, which circuit in turn rests on a substrate or mother-board.

FIG. 2 illustrates a process for preparing multilayer printed circuits.

Claims

1. A composition comprising: an epoxy and a cross-linking agent reactive therewith; or the cross-linked reaction product of said epoxy and said cross-linking agent, and 20 to 60% by weight, relative to the total combined weight of the epoxy plus cross-linking agent or total weight of said reaction product, of a particulate mixture dispersed therein, said particulate mixture being characterized by a bimodal particle size distribution of nanoscale particles.

2. The composition of claim 1 wherein the particulate mixture comprises a smaller particle population and a larger particle population, the smaller particle population representing 10 to 30% by weight of the total weight of the particulate mixture.

3. The composition of claim 2 wherein the smaller particle population consists essentially of fumed silica.

4. The composition of claim 3 wherein the larger particle population consists essentially of spherical silica or nano-clay.

5. A process comprising forming a composition by combining in a suitable solvent an epoxy resin comprising epoxide groups, a cross-linking agent reactive with said epoxide groups, and 20 to 60% by weight based upon the weight of the epoxy plus cross-linking agent of a particulate mixture comprising a bimodal particle size distribution of nano-scale particles; and, agitating said composition to create a substantially homogeneous mixture.

6. The process of claim 5 further comprising curing said composition.

7. The process of claim 5 wherein the particulate mixture comprises a smaller particle population and a larger particle population, the smaller particle population representing 10-30% by weight of the total weight of the particulate mixture.

8. The process of claim 7 wherein the smaller particle population comprises fumed silica.

9. The process of claim 8 wherein the larger particle population comprises spherical silica or nano-clay.

10. A film or sheet comprising an epoxy and a cross-linking agent reactive therewith, or the cross-linked reaction product thereof, and 20 to 60% by weight, relative to the weight of the epoxy plus cross-linking agent, of a particulate mixture dispersed therein, said particulate mixture characterized by a bimodal particle size distribution of nanoscale particles.

11. The film or sheet of claim 10 wherein the particulate mixture comprises a smaller particle population and a larger particle population, the smaller particle population representing 10-30% by weight of the total weight of the particulate mixture.

12. The film or sheet of claim 11 wherein the smaller particle population comprises fumed silica.

13. The process of claim 12 wherein the larger particle population comprises spherical silica or nano-clay.