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Packaging Structure with the Ground Plane on Top of the Wiring

IP.com Disclosure Number: IPCOM000045075D
Original Publication Date: 1983-Jan-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 3 page(s) / 74K

Publishing Venue

IBM

Related People

Geldermans, P: AUTHOR

Abstract

Described is a technique for planarization of fine line wiring and wire bonding, and deleting problems on polyimide coatings. In order to obtain more powerful wiring capability, one needs a fine line capability (etched) on top of multilayer ceramic (MLC). In this kind of structure there is a need for a ground or reference plane in order to reduce the noise and provide a controlled line impedance. A natural way to obtain this impedance would be to make a continuous ground plane.

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Packaging Structure with the Ground Plane on Top of the Wiring

Described is a technique for planarization of fine line wiring and wire bonding, and deleting problems on polyimide coatings. In order to obtain more powerful wiring capability, one needs a fine line capability (etched) on top of multilayer ceramic (MLC). In this kind of structure there is a need for a ground or reference plane in order to reduce the noise and provide a controlled line impedance. A natural way to obtain this impedance would be to make a continuous ground plane.

However, a continuous ground plane enhances the chances for interlevel shorts. For this reason one can "personalize" the ground plane.

The structure, however, has a number of disadvantages, one being that the engineering change (EC) pads are located on top of the polyimide dielectric. The polyimide is a less than ideal material under EC pads. It is not strong and not thermally stable.

The structure that is the subject of this technique places the fine line wiring and the EC pads on top of a glass layer. This permits optimum conditions for wire bond and delete, optimum conditions for making and repairing the fine line wiring, and optimum conditions for testing fine line wiring. The less critical reference plane is placed over the fine line wiring. One can use the inexpensive polyimide or glass, if so desired, as insulator for this purpose. The key aspects of the new structure are:

1. A thin glass layer over the MLC, with etched vias to the MLC

studs (Fi...