Browse Prior Art Database

Chip Attachment to Tape and Cable

IP.com Disclosure Number: IPCOM000050138D
Original Publication Date: 1982-Sep-01
Included in the Prior Art Database: 2005-Feb-10
Document File: 2 page(s) / 45K

Publishing Venue

IBM

Related People

Edwards, JC: AUTHOR

Abstract

This article describes a method to electronically attach integrated circuits directly to printed circuit boards or flex circuits, to provide encapsulation (passivation) of the circuit, and to enhance the dissipation of heat from the circuit. These features are provided by combining a chip with solder balls at each pin and a modified form of commercially available beam tape. An integrated circuit (IC) chip is soldered to a polyimide/ copper tape. A portion of this tape is stamped out and used to connect to a flex circuit that has been rigidized with an aluminum heat sink. The chip itself is in direct contact with the heat sink, and the whole assembly is sealed against the outside environment with a thermal adhesive at the periphery of the stamped out tape.

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Chip Attachment to Tape and Cable

This article describes a method to electronically attach integrated circuits directly to printed circuit boards or flex circuits, to provide encapsulation (passivation) of the circuit, and to enhance the dissipation of heat from the circuit. These features are provided by combining a chip with solder balls at each pin and a modified form of commercially available beam tape. An integrated circuit (IC) chip is soldered to a polyimide/ copper tape. A portion of this tape is stamped out and used to connect to a flex circuit that has been rigidized with an aluminum heat sink. The chip itself is in direct contact with the heat sink, and the whole assembly is sealed against the outside environment with a thermal adhesive at the periphery of the stamped out tape. The result is a completely automated, low cost and high density (100 contacts or more) package.

Fig. 1 is a cross section of the final assembly. This is applicable to chips with two dimensional arrays of contacts which normally must be used with metallized ceramic substrates. Conventional beam tape is used which has not had the polyimide etched away and the circuit fingers exposed. The polyimide provides support for an intricate circuit interconnection pattern.

The process begins with a sandwich of polyimide and copper in a standard tape format. The copper is etched away leaving an interconnection pattern (Fig.
2). The resulting tape is then run through a stamping die to indent...