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Engineering topics

Dunnavant, W. R.

Publications and source records attributed to Dunnavant, W. R..

Development of a highly reliable composite board for printed circuitry for use in space environment

Materials, processes and fabrication techniques have been investigated for the development of a high-temperature circuit-board laminate. High quality, void-free copper-clad laminates have been made using 7628/HS-1 style fiberglas reinforcements with filled polyimide matrices. The fabricating characteristics of P13N resin appear suitable for use as a filled matrix in this circuit board development. High-fired, ball-milled alumina appears to be necessary to obtain the desired effects in the circuit board system. Nickel-clad copper foil bonding surfaces appear to be another requirement for retention of good bond strengths after art work and plating sequences. The fabrication cycle for this circuit board system is very dependent on the heating profile. Very rapid heating with quick loading is recommended. A stack approach to lamination was successfully used.

Bradbury, E. J.↗

Coatings from copolymers of tetraphenoxysilane and p,p(1)-biphenol

Resultant resin from copolymers is highly crosslinked and completely aromatic. Procedure develops polyaryoxysilane structure in situ after the substrate has first been coated with a prepolymer. Resins are useful as protective coatings for metals, ceramics, glass, and other materials that accommodate relatively high curing temperatures.

Dunnavant, W. R.↗

Improved process for synthesizing anilinosilane compounds

New process gives good yields of anilinosilane compounds that can be readily isolated in a high state of purity. S-collidine is used as an HCl acceptor. Silane compounds can be melt-condensed with aromatic diols to provide high molecular weight polyaryloxysilane materials that are of importance in polymer technology.

Dunnavant, W. R.↗