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Method of Sealing Polyamide Organic Laminates

IP.com Disclosure Number: IPCOM000089247D
Original Publication Date: 1977-Oct-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Greer, SE: AUTHOR

Abstract

Concentrated sulfuric acid is one of the few materials that attacks aromatic polyamide fiber, such as KEVLAR*. By placing an organic laminate in this acid for approximately 1 to 5 minutes at room temperature to about 130 Degrees F, it is observed that the aromatic polyamide fiber does not readily dissolve but rather forms a fused, glassy melt along the edges of the laminate, which then slowly dissolves along with the polymer matrix, for example, epoxy or polyimide. This glassy edge layer both improves the visual character of rough cut laminates and seals them against further ingress or moisture and chemicals.

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Method of Sealing Polyamide Organic Laminates

Concentrated sulfuric acid is one of the few materials that attacks aromatic polyamide fiber, such as KEVLAR*. By placing an organic laminate in this acid for approximately 1 to 5 minutes at room temperature to about 130 Degrees F, it is observed that the aromatic polyamide fiber does not readily dissolve but rather forms a fused, glassy melt along the edges of the laminate, which then slowly dissolves along with the polymer matrix, for example, epoxy or polyimide. This glassy edge layer both improves the visual character of rough cut laminates and seals them against further ingress or moisture and chemicals.

Drilled aromatic polyamide laminate through-holes, which tend to show polymer "drill smear" and fibrous residues, show marked improvement after sulfuric acid etching. The holes are clear of fiber, smooth bored, and are sufficiently etched back to reveal internal planes previously masked by the smeared aromatic polyamide laminate. These treated through-holes can then be more reliably plated.

In an alternate scheme, the aromatic polyamide fiber alone is dissolved in concentrated sulfuric acid forming a "dope", which then can be used to selectively coat and seal the organic laminate. * Trademark of E. I. du Pont de Nemours & Co.

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