Nanoporous laminates
View Patent ↗A process of making a nanoporous substrate, such as the matrix in an electrical laminate, by grafting onto an organic resin backbone a thermolabile functionality by reacting hydrogen active groups of the organic resin with a compound containing thermolabile groups; then thermally degrading the thermolabile groups grafted on the organic resin to form a nanoporous laminate. Advantageously, the nanoporous electrical laminate has a low dielectric constant (Dk) because of the nanopores present in the laminate matrix.
1. A process for making a nanoporous substrate comprising the steps of:
(a) grafting onto a backbone of an organic resin, a thermolabile functionality by reacting hydrogen active groups of the organic resin with a compound containing thermolabile group;
(b) preparing a composition by blending the organic resin containing thermolabile groups with at least a curing agent; and
(c) thermally degrading the thermolabile groups grafted on the organic resin such as to produce a nanoporous substrate.
2. The process of claim 1 wherein the substrate is a laminate.
3. The process of claim 1 wherein the organic resin is selected from the group consisting of epoxy resins, phenolic resins, polyimide resins, polyamide resins, polyester resins, polyether resins, bismaleimide triazine resins, cyanate ester resins, vinyl ester resins, hydrocarbon resins, and mixture of thereof.
4. The process of claim 1 wherein the organic resin is an epoxy resin.
5. The process of claim 1 wherein the organic resin is a brominated epoxy resin.
6. The process of claim 1 wherein the organic resin is a phosphorus-containing epoxy resin.
7. The process of claim 1 wherein the organic resin is an epoxy resin with an epoxy equivalent weight higher than 500.
8. The process of claim 1 wherein the hydrogen active group is selected from the group consisting of amines, phenols, thiols, hydroxyls, alcohols, amides, lactams, carbamates, pyrroles, mercaptans, imidazoles, guanidine and mixtures thereof.
9. The process of claim 1 wherein the compound containing the thermolabile group is selected from the group consisting of dicarbonates, derivatives of dicarbonates, carbazates, derivatives of carbazates, and mixtures thereof.
10. The process of claim 1 wherein the compound containing the thermolabile group is tert-butyl dicarbonate.
11. The process of claim 1 wherein the thermolabile group is a carbonate.
12. The process of claim 1 wherein the thermolabile group is tert-butyl carbonate.
13. The process of claim 1 wherein the thermolabile group is present in the composition in an amount such that the weight percent of thermolabile groups in the composition is between about 0.01 weight percent and about 10 weight percent, based on solids.
14. The process of claim 1 including a solvent.
15. The process of claim 14 wherein the solvent is a ketone, an acetate of glycol ethers or mixtures thereof.
16. The process of claim 14 wherein the solvent is present in an amount of from about 10 parts to about 60 parts.
17. The process of claim 1 including a catalyst for the reaction between the organic resin and the compound containing the thermolabile group.
18. The process of claim 17 wherein the catalyst is dimethyl aminopyridyne.
19. The process of claim 1 wherein the reaction between the organic resin and the compound containing the thermolabile group is done at a temperature of from about 15° C. to about 45° C.
20. The process of claim 1 including adding a thermoplastic compound to the composition to lower the dielectric constants.
21. The process of claim 20 wherein the thermoplastic compound is polyphenylene ether, polyphenylene oxide, or allylated polyphenylene ether.