Browse Prior Art Database

A Flexible Pullup Network for Surface Mount Packaging

IP.com Disclosure Number: IPCOM000103401D
Original Publication Date: 1990-Nov-01
Included in the Prior Art Database: 2005-Mar-17
Document File: 1 page(s) / 42K

Publishing Venue

IBM

Related People

Harper, JD: AUTHOR [+2]

Abstract

Disclosed is a pullup network built upon a flexible carrier. The network is composed of resistors screened onto a flexible carrier and laser-trimmed to the appropriate pullup resistor value. These networks can be placed on top of the transmitting or receiving device whose signals it will terminate and maintain a short path between the signals and the terminators, as in Figure 1. In addition to minimizing path length, this network does not require any board space or additional wiring. (Image Omitted)

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A Flexible Pullup Network for Surface Mount Packaging

      Disclosed is a pullup network built upon a flexible carrier.
The network is composed of resistors screened onto a flexible carrier
and laser-trimmed to the appropriate pullup resistor value. These
networks can be placed on top of the transmitting or receiving device
whose signals it will terminate and maintain a short path between the
signals and the terminators, as in Figure 1.  In addition to
minimizing path length, this network does not require any board space
or additional wiring.

                            (Image Omitted)

      The carrier may be common flex circuit material, a polyimide
insulating layer with a copper foil wiring plane attached to it with
an acrylic glue.  It may be a single signal layer carrier with the
copper layer etched to a pattern for the resistor pads and to connect
between the resistor terminals and the signal pins, and between the
resistor terminals and the power bus.

      The resistors are made with polymer pastes commonly used for
screened resistor applications.  The shape, particular paste, and
trimming pattern are chosen on the basis of the nominal resistance
value required for the termination job.  The thickness of the copper
layer of the flex, as well as the copper trace thickness on the flex
will likewise be chosen based on circuit current requirements.

      Disclosed anonymously.