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ESD-resistant embedded capacitance structure

IP.com Disclosure Number: IPCOM000124987D
Original Publication Date: 2005-May-17
Included in the Prior Art Database: 2005-May-17
Document File: 2 page(s) / 32K

Publishing Venue

Motorola

Related People

Robert Croswell: AUTHOR [+2]

Abstract

Embedded capacitance is needed for electronic assemblies such as circuit boards and IC packages to allow reduced size and cost and improved electrical performance. Motorola is working on an advanced embedded capacitance technology that employs a thin (sub-micron), high permittivity perovskite dielectric such as lead zirconate titanate (PZT). The basic concept is to form the perovskite film on a metal foil and subsequently laminate the metal foil into an organic circuit board structure comprising such materials as FR-4 (glass-reinforced epoxy). This approach allows the high temperature (600ºC) crystallization of the perovskite to be performed on the metal foil prior to integration with organic board materials that are incompatible with such temperaturesv

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ESD-resistant embedded capacitance structure

Robert Croswell and Gregory Dunn

Embedded capacitance is needed for electronic assemblies such as circuit boards and IC packages to allow reduced size and cost and improved electrical performance.  Motorola is working on an advanced embedded capacitance technology that employs a thin (sub-micron), high permittivity perovskite dielectric such as lead zirconate titanate (PZT).  The basic concept is to form the perovskite film on a metal foil and subsequently laminate the metal foil into an organic circuit board structure comprising such materials as FR-4 (glass-reinforced epoxy).  This approach allows the high temperature (600ºC) crystallization of the perovskite to be performed on the metal foil prior to integration with organic board materials that are incompatible with such temperatures.


Motorola's effort is focused on lead lanthanum zirconate titanate (PLZT) or lead calcium zirconate titanate (PCZT) dielectrics formed by chemical solution deposition (or sol gel) techniques on copper foil plated with nickel-phosphorus, as described in U.S. 6,541,137.  Copper foil is the material of choice for circuit board fabrication due to its excellent electrical, mechanical, and chemical properties, and its low price.  


An important concern regarding the long-term reliability of such embedded thin film dielectrics is whether they can withstand electrostatic discharges (ESD) without sustaining permanent damage such as plate-to-plate shorts through the thin dielectric.

Littelfuse has developed ESD protection devices comprising voltage variable materials that become conductive at high voltages but are non-conductive at low voltages.  These surface mount components are fabricated at low cost by employing printed circuit board materials and processes.   Such devices could be embedded in a printed circuit board to protect embedded capacitors from ESD events...