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Thick Film Termination of Low Inductance Ceramic Chip Capacitors

IP.com Disclosure Number: IPCOM000050115D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 3 page(s) / 67K

Publishing Venue

IBM

Related People

Humenik, JN: AUTHOR [+2]

Abstract

Low inductance ceramic chip capacitors (tab capacitors) have been proposed for use as a decoupling capacitor on substrates (Fig. 1). The low inductance of such a capacitor is derived from the multiple tab leads to each internal plate, the shorting bars tying together tabs of a similar voltage, and the multiple solder ball interconnections between the capacitor and the substrate.

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Thick Film Termination of Low Inductance Ceramic Chip Capacitors

Low inductance ceramic chip capacitors (tab capacitors) have been proposed for use as a decoupling capacitor on substrates (Fig. 1). The low inductance of such a capacitor is derived from the multiple tab leads to each internal plate, the shorting bars tying together tabs of a similar voltage, and the multiple solder ball interconnections between the capacitor and the substrate.

The capacitor termination (shorting bars, solder dam, and solder balls) can be applied by either thin or thick film techniques.

Since many capacitor vendors, per se, do not have thin film capabilities, thin film termination would have to be done within house. Such a scheme becomes quite cumbersome from a quality assurance standpoint. Therefore, the prime advantage of thick film termination is that the vendor who makes the bulk capacitor can also terminate it. This enables one to purchase a fully completed, testable component. Disclosed herein is the concept of using thick film termination on tab capacitors as well as processing schemes that might be used to achieve the objectives.

SHORTING BARS

The shorting bars are to be 0.005 inch wide on 0.009 inch centers, and they can traverse the complete width of the tab capacitor. Because there exists only a
0.004 inch gap between bars of dissimilar voltages, the metals used should be non migrating. Potential metals would include, but not be restricted to, nickel, copper, and palladium applied in a paste form through a geometrically appropriate screen or mask.

In most cases the shorting bars would be screened onto already fired capacitors and then be densified by a subsequent heat treatment. The use of similar metals for the capacitor plates and shorting bars would enable the ba...