Browse Prior Art Database

Bottom Terminated, Low Inductance Ceramic Chip Capacitor

IP.com Disclosure Number: IPCOM000052506D
Original Publication Date: 1981-Jun-01
Included in the Prior Art Database: 2005-Feb-11
Document File: 4 page(s) / 113K

Publishing Venue

IBM

Related People

Humenik, JN: AUTHOR

Abstract

Decoupling capacitors serve as sources of readily available power for the switching of logic chips. These capacitors discharge rapidly to provide the switching current, and then are recharged by an external power source. The switching speed of the logic circuit is thus closely related to the inductance of the current path between the chip and the capacitor.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 4

Bottom Terminated, Low Inductance Ceramic Chip Capacitor

Decoupling capacitors serve as sources of readily available power for the switching of logic chips. These capacitors discharge rapidly to provide the switching current, and then are recharged by an external power source. The switching speed of the logic circuit is thus closely related to the inductance of the current path between the chip and the capacitor.

Minimizing the inductance involves placing the chip and the capacitor in close proximity and offering a large number of short current paths between the chip and the capacitor. One approach is in the design of a package which places the decoupling capacitors directly adjacent to each chip on top of the substrate.

Described herein is a capacitor design capable of achieving low inductance and of operating in close proximity to logic chips.

A basic illustration of the disclosed capacitor is given in Fig. 1. It should be noted that while the dimensions specifically apply to one size of capacitor, the concept and design are applicable to almost any size component and variable sheet thicknesses.

Basically, the capacitor is comprised of a high dielectric constant ceramic cofired with a compatible metallurgy using techniques conventional to the ceramic chip capacitor industry. Unique to the disclosed design is that all of the metal plates exit one side of the capacitor and, for structural integrity, a trapezoidal plate is used. After thick film fabrication, thin film processing is required to provide the low inductance termination through vias and shorting strips.

The thick film capacitor is fabricated in accordance with the current state of the art in ceramic chip capacitors. That this is the case is the most important aspect of the capacitor design. Thick film fabrication can use greensheet ceramic with screened metal plates or alternate screenings of dielectric and metallurgy. While it is preferable to provide the capacitors in a "master slice" comprised of a plurality of indiv...