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BALL GRID ARRAY IC PACKAGE INCORPORATING LOW-COST INTEGRAL INDUCTORS

IP.com Disclosure Number: IPCOM000009743D
Original Publication Date: 2000-May-01
Included in the Prior Art Database: 2002-Sep-16
Document File: 1 page(s) / 66K

Publishing Venue

Motorola

Related People

Gregory Dunn: AUTHOR [+4]

Abstract

Discrete inductors assembled onto the printed circuit board take up space, add cost, assembly complexity and reliability concerns, and present a long signal path to the integrated circuit (IC), resulting in large parasitics.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 84% of the total text.

MOTOROLA

Technical Developments

BALL GRID ARRAY IC PACKAGE INCORPORATING LOW-COST INTEGRAL INDUCTORS

by Gregory Dunn, Larry Lach, Roger Forse and Allyson Beuhler

PROBLEM

Discrete inductors assembled onto the printed circuit board take up space, add cost, assembly complexity and reliability concerns, and present a long signal path to the integrated circuit (IC), resulting in large parasitics. Various technologies for fabricating inductors directly on the IC are being investigated, but these are expensive, yield low inductor quality factor (Q < 20), and are limited to low inductance values ( < 20 nH).

SOLUTION

A Ball Grid Array (BGA) package can incorporate a two-layer copper winding inductor as part of the interconnect. BGA package interposers, particularly perimeter array packages, generally do not

Microvla layer on interposer

L

4x4 mm unused space

make full use of the available area. This invention exploits that unused area to provide an inductor or inductors with a very short signal path to the chip, making them ideal for applications such as a voltage controlled oscillator tank circuit, for which it is highly desirable to have the inductor close to the varactor and capacitor on the chip. Values up to 200 nH are possible within a 2.5 mm diameter for 2 mil line and space interconnect.

The inductor(s) could be fabricated on the top or bottom of the interposer; the bottom (board) side may be the preferred location, because this allows an optional ground plane to be fabricated...