Circuit substrate material, circuits comprising the same, and method of manufacture thereof
View Patent ↗An electrical circuit material having a conductive layer disposed a substrate, wherein the substrate is formed from a thermosetting composition comprising a polybutadiene or polyisoprene resin; an optional, functionalized liquid polybutadiene or polyisoprene resin; an optional butadiene- or isoprene-containing copolymer; an optional low molecular weight polymer; an optional curing agent; a cross-linking agent; a particulate fluoropolymer; and about 20 to about 50 percent by weight, based on the total weight of the thermosetting composition, of a magnesium hydroxide having a low ionic content. Use of magnesium hydroxide allows the composition to attain a high level of flame retardancy without use of halogenated flame retardants, while maintaining good moisture absorption and other physical properties.
1. An electrical circuit material comprising a conductive layer disposed a substrate, wherein the substrate is formed from a thermosetting composition comprising:
a polybutadiene or polyisoprene resin;
a cross-linking agent;
a particulate fluoropolymer; and
about 20 to about 50 percent by weight, based on the total weight of the thennosetting composition, of a magnesium hydroxide having less than about 1000 ppm of ionic contaminants; wherein the substrate has a UL-94 rating of at least V-1.
2. The electrical circuit material of claim 1 , wherein the thennosetting composition further comprises a butadiene- or isoprene-containing copolymer.
3. The electrical circuit material of claim 2 , wherein the butadiene- or isoprene-containing copolymer is an unsaturated butadiene- or isoprene-containing copolymer.
4. The electrical circuit material of claim 3 , wherein the volume to volume ratio of the polybutadiene or polyisoprene resin to the unsaturated butadiene- or isoprene-containing copolymer is between 1:9 and 9:1, inclusive.
5. The electrical circuit material of claim 1 , wherein the thermosetting composition further comprises a curing agent.
6. The electrical circuit material of claim 5 , wherein the curing agent is an organic peroxide, a dicumyl peroxide, a di(2-tert-butylperoxyisopropyl) benzene, a t-butylperbenzoate, a t-butylperoxy hexyne-3, or a combination comprising one or more of the foregoing curing agents.
7. The electrical circuit material of claim 1 , wherein the thermosetting composition further comprises a low molecular weight polymer.
8. The electrical circuit material of claim 1 , wherein the thermosetting composition further comprises a functionalized liquid polybutadiene or polyisoprene resin.
9. The electrical circuit material of claim 1 , wherein the cross-linking agent is triallylisocyanurate, triallylcyanurate, diallyl phthalate, divinyl beuzene, a multifunctional acrylate monomer, or a combination comprising one or more of the foregoing cross-linking agents.
10. The electrical circuit material of claim 1 , wherein the particulate fluoropolymer is a difluoroethylene polymer, a tetrafluoroethylene polymer, a tetrafluoroethylene-hexafluoropropylene copolymer, a copolymer of tetrafluoroethylene with fluorine-free ethylenic monomers, or a combination comprising one or more of the foregoing particulate fluoropolymers.
11. The electrical circuit material of claim 1 , wherein the substrate has a moisture absorption value less than about 0.2% and a UL-94 flammability rating of V-0.
12. The electrical circuit material of claim 1 , wherein the substrate has a dielectric constant less than about 4.5 and a dielectric loss factor less than about 0.01.
13. The electrical circuit material of claim 1 , wherein the conductive layer is copper.
14. The electrical circuit material of claim 1 , wherein the thermosetting composition further comprises a woven or non-woven glass web.
15. The electrical circuit material of claim 1 , wherein the magnesium hydroxide comprises less than about 500 ppm of metal.
16. The electrical circuit material of claim 1 , wherein the thermosetting composition further comprises a chlorine-containing flame retardant, a bromine-containing flame retardant, or a combination comprising one or more of the foregoing flame retardants.
17. The electrical circuit material of claim 1 , wherein the magnesium hydroxide has an average surface area of about 3 to about 12 meters squared per gram.
18. The electrical circuit material of claim 1 , wherein the magnesium hydroxide is coated with an aminosilane.
19. The electrical circuit material of claim 1 , further comprising a filler.
20. The electrical circuit material of claim 19 , where the filler further comprises a coupling agent.
21. The electrical circuit material of claim 20 , where the coupling agent is a silane.
22. A circuit comprising the electrical circuit material of claim 1 .
23. A substrate for an electrical circuit material, wherein the substrate comprises a thermosetting composition comprising:
a polybutadiene or polyisoprene resin;
a cross-linking agent;
a particulate fluoropolymer; and
about 20 to about 50 percent by weight, based on the total weight of the thermosetting composition, of a magnesium hydroxide having less than about 1000 ppm of ionic contaminants; wherein the substrate has a UL-94 rating of at least V-1.