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Thermal Expansion Controlled Ground and Voltage Planes

IP.com Disclosure Number: IPCOM000037974D
Original Publication Date: 1989-Sep-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Camp, MM: AUTHOR [+7]

Abstract

This disclosure describes a method for obtaining ground voltage and shielding planes that have the thermal expansion (CTE) characteristics between those of glass (4-6PPM) or other fabric materials (0-6PPM) and a metal coating.

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Thermal Expansion Controlled Ground and Voltage Planes

This disclosure describes a method for obtaining ground voltage and shielding planes that have the thermal expansion (CTE) characteristics between those of glass (4-6PPM) or other fabric materials (0-6PPM) and a metal coating.

The ultimate goal in circuit board fabrication is a low CTE (4-6PPM), high temperature card which allows C-4 bonding of chips directly to the card surface. To achieve this goal, layer materials in the composite must be closely matched to minimize stresses within the structure. The Copper-Invar-Copper (CIC) currently used is expensive and difficult to process through drill and/or etch. Invar is a Registered Trademark of Imphy S.A., Paris, France.

The disclosure is metallized glass fabric. The fabric type is chosen for thickness, weave configuration, and CTE control. The metal (preferably copper) can be selected for electrical conductivity, thermal conductivity and CTE.

The process is to attach glass fabric to a frame and process thru Pd/Sn type seed, followed by electroless copper plating. The amount of plating is determined by the type of electrical plane desired; thin copper for shielding, thick copper for power layers.

At this point, the fabric will behave like a continuum and has properties close to the strongest member (i.e. glass). The metallized fabric is then treated for adhesion and laminated. The plane can be drilled for power core personalization or used for shielding or as a...