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Surface Porosity Improvements

IP.com Disclosure Number: IPCOM000083883D
Original Publication Date: 1975-Aug-01
Included in the Prior Art Database: 2005-Mar-01
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Brownlow, J: AUTHOR [+3]

Abstract

Green alumina sheets normally have a resin rich layer that forms during drying on the top (dull side) and bottom (shiny side) of the sheet. This exists as a complete polymer coating over and between the ceramic particles reventing the absorption of paste solvent, and is a problem with certain noninteractive metallurgical pastes.

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Surface Porosity Improvements

Green alumina sheets normally have a resin rich layer that forms during drying on the top (dull side) and bottom (shiny side) of the sheet. This exists as a complete polymer coating over and between the ceramic particles reventing the absorption of paste solvent, and is a problem with certain noninteractive metallurgical pastes.

Sheet screening quality is significantly improved by opening the sheet surface structure, thereby allowing for quick penetration and fast absorption of the oil solvent in the pastes. The sheet structure of the green alumina sheet is made very porous by heat treating the sheet at 90 degrees C for 30 minutes. This causes the polymer film to melt and while in a state of low viscosity, to collapse around the ceramic particles on the sheet surface.

This change in binder rheology and the reduction in the surface tension of the thin polymer film, creates a desirable sheet porosity. This porosity uniquely forms on both surfaces of the green sheet, making them highly absorbant for the metallurgical paste.

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