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Simplified Method of Preparing Capacitors for Bonding to Substrates

IP.com Disclosure Number: IPCOM000037723D
Original Publication Date: 1989-Jun-01
Included in the Prior Art Database: 2005-Jan-29
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Seraphim, DP: AUTHOR [+2]

Abstract

The increased demands caused by the introduction of simultaneously switching has caused the initiation of specially prepared chip capacitors in order to improve the performance of modules. The special preparation consists of adding islands of metal and BLM metallurgy with C4 solder to one surface of a base capacitor to enable the bonding of the capacitor simultaneously with the chip to a substrate.

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This is the abbreviated version, containing approximately 73% of the total text.

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Simplified Method of Preparing Capacitors for Bonding to Substrates

The increased demands caused by the introduction of simultaneously switching has caused the initiation of specially prepared chip capacitors in order to improve the performance of modules. The special preparation consists of adding islands of metal and BLM metallurgy with C4 solder to one surface of a base capacitor to enable the bonding of the capacitor simultaneously with the chip to a substrate.

In accordance with the simplified method, a basic capacitor is made up usually of 32 layers of screen printed platinum electrodes on barium titanate ceramic plates. These are stacked and laminated to form a sandwich structure. The screen printed metal is shaped to produce two contact strips on each electrode at one face of each capacitor chip. These electrode contacts can be used to define additions of desirable metals, such as electroless copper plating, so that 10 to 20 microns of plating can be built up, without masking or any other preparation, to form plated "bumps". These bumps are rounded by the nature of the plating process and are of uniform height since this surface of the capacitor is ground and lapped flat. An over plating with immersion gold, or other suitable metal, to facilitate joining to this substrate metallization surface, completes the processing, and the capacitor is ready for direct bonding to a substrate pattern. Several choices of joining metallurgy and process exist. Any suitab...