Browse Prior Art Database

Laser Etching of Green Sheet Ceramic

IP.com Disclosure Number: IPCOM000039304D
Original Publication Date: 1987-May-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Olson, RW: AUTHOR

Abstract

This is a method for selectively etching surface features of controllable depth into ceramic green sheets. This allows, for example, simplified construction of integrated capacitors in MLC (multilayer ceramic) substrates and creation of conductors of larger cross section that surface screening techniques allow. For densely packaged high-speed devices it is advantageous to include low-inductance integrated capacitors in an MLC package to provide fast-response smoothing of supply voltage switching transients to eliminate spurious signal level switching. To achieve high integrated capacitance per unit volume, high-dielectric-constant (high-k) materials and/or thin layers are needed.

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Laser Etching of Green Sheet Ceramic

This is a method for selectively etching surface features of controllable depth into ceramic green sheets. This allows, for example, simplified construction of integrated capacitors in MLC (multilayer ceramic) substrates and creation of conductors of larger cross section that surface screening techniques allow. For densely packaged high-speed devices it is advantageous to include low- inductance integrated capacitors in an MLC package to provide fast-response smoothing of supply voltage switching transients to eliminate spurious signal level switching. To achieve high integrated capacitance per unit volume, high- dielectric-constant (high-k) materials and/or thin layers are needed. In contrast to this need, the low-dielectric-constant (low-k) ceramic used in these packages helps minimize signal propagation delays and the sheets are thick enough to handle easily and minimize coupling between lines on successive layers. While high-k sheets can be inserted into the MLC structure, handling considerations, rather than capacitance, may determine sheet thickness. Laser etching can selectively thin (to 1 mil or less) areas of green sheets (of high or low k) designated for integrated capacitors. The etched areas can be directly filled with metal paste to yield thick, embedded capacitor electrodes (separated by thin, unetched dielectric); used as sites to place completed thin-film capacitors; or used to build layered structures of alternate metal paste electr...