Browse Prior Art Database

Aid for Electronic Package Lead Alignment

IP.com Disclosure Number: IPCOM000039990D
Original Publication Date: 1987-Sep-01
Included in the Prior Art Database: 2005-Feb-01
Document File: 2 page(s) / 42K

Publishing Venue

IBM

Related People

Munroe, RA: AUTHOR

Abstract

A method is described which facilitates the alignment of leads during handling and mounting to a substrate. During lead frame fabrication, add a chemical and temperature-resistant electrical insulator to keep leads in alignment. The location should be so that subsequent forming and mounting operations are not hampered. The lead frame alignment aid could also be added after molding and before excising. During the excise operation, the selvage and mold dam bar are removed. They are usually metal parts of the lead frame designed to facilitate lead alignment and to limit mold flash. Once they are removed, the leads are formed. As electronic packages get smaller and have more leads, the leads are more easily deformed from their original position; yet the smaller more numerous leads require more critical alignment.

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Aid for Electronic Package Lead Alignment

A method is described which facilitates the alignment of leads during handling and mounting to a substrate. During lead frame fabrication, add a chemical and temperature-resistant electrical insulator to keep leads in alignment. The location should be so that subsequent forming and mounting operations are not hampered. The lead frame alignment aid could also be added after molding and before excising. During the excise operation, the selvage and mold dam bar are removed. They are usually metal parts of the lead frame designed to facilitate lead alignment and to limit mold flash. Once they are removed, the leads are formed. As electronic packages get smaller and have more leads, the leads are more easily deformed from their original position; yet the smaller more numerous leads require more critical alignment. By providing an electrical insulator across leads, the mechanical alignment and thus the subsequent manufacturing operations are made more productive. The electrical insulator could be polyimide (or polyamide) tape, or some similar material. Some possible configurations are shown in the figure. The tape or insulator could be added before or after molding. Leads could be on two or four sides and formed to any configuration.

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