High density para-aramid papers
AssigneeE. I. Du Pont de Nemours and Company
InventorEdward W. Tokarsky
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Abstract
High density para-aramid papers comprising 5 to 25 percent, by weight, binder and an amount of para-aramid fibers selected from the group consisting of para-aramid pulp, para-aramid floc and mixtures thereof, compacted to provide a volume percent para-aramid fiber of at least 53 minus 0.13 times the volume percent floc in the paper are useful in the preparation of circuit board substrates having a low coefficient of thermal expansion.
Claims15
High density para-aramid paper for use in an electrical circuit board laminates having low coefficient of thermal expansion comprising 5 to 15 percent, by weight, based on the total solids content of the paper, of a polymeric binder of aramid fibrids and short para-aramid fibers made up of 0-50 volume percent para-aramid pump and 50-100 volume percent para-aramid floc having lengths of 0.8 to 12.7 mm, the fibers being compacted at a nip pressure of 1500 to 5000 lbs/inch (268 to 894 kg/cm) to provide a volume percent para-aramid fiber in the paper of at least 53 minus 0.13 times the volume percent para-aramid floc in the fibers.
High density para-aramid paper for use in electrical circuit board laminates having low coefficient of thermal expansion comprising 5 to 15 percent, by weight, of a water dispersible polymeric binder selected from the group consisting of epoxy resins, phenolic resins, polyester resins, polyureas, polyurethanes, melamine formaldehyde resins, and fluorocarbon resins and short para-aramid fibers made up of 0-50 volume percent para-aramid pulp and 50-100 volume percent para-aramid floc having lengths of 0.8 to 12.7 mm, the fibers being compacted at a nip pressure of 1500 to 5000 lbs/inch (268 to 894 kg/cm) to provide a volume percent para-aramid fiber in the paper of a least 53 minus 0.13 times the volume percent para-aramid floc in the fibers.
Dependencies are inferred from the claim text.