Browse Prior Art Database

Tape Automated Bonding Connection Method to Thick Film Screened Circuit Board

IP.com Disclosure Number: IPCOM000040022D
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Frankeny, R: AUTHOR

Abstract

A method is described for use in integrated circuit (IC) chip wiring using the tape automated bonding (TAB) package to decrease the wiring area because of fan-out required to get to vias that enable wiring to other wiring planes. High lead count devices need to connect to other devices to create a logic system. When multiple devices are used to create a system, multilayer circuit boards are used often to allow enough wire channels to make all the necessary wire routings. A package like TAB has the capability of high lead count. All the leads are brought out peripherally for attachment to a second level package, e.g., a printed circuit card. These cards can have multiple wiring planes necessary to distribute all the wires from a high lead count device. Connection between these planes may require a via hole.

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Tape Automated Bonding Connection Method to Thick Film Screened Circuit Board

A method is described for use in integrated circuit (IC) chip wiring using the tape automated bonding (TAB) package to decrease the wiring area because of fan- out required to get to vias that enable wiring to other wiring planes. High lead count devices need to connect to other devices to create a logic system. When multiple devices are used to create a system, multilayer circuit boards are used often to allow enough wire channels to make all the necessary wire routings. A package like TAB has the capability of high lead count. All the leads are brought out peripherally for attachment to a second level package, e.g., a printed circuit card. These cards can have multiple wiring planes necessary to distribute all the wires from a high lead count device. Connection between these planes may require a via hole. The card technology determines how far the device leads must fan-out before a via can be used. This causes increased wiring area and thus board space. The new method uses a thick film polyimide circuit card which is made by screening a thin layer of polyimide on an insulated aluminum substrate, but any substrate including ceramic may be used. Since these layers are very thin, a 1-2-mil connection to each signal layer can be done by exposing the desired layer to the group of wires requiring interconnection at the TAB/board interface point. In this manner TAB leads can be directly conn...