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Insuring the Hermeticity of Chip Packages

IP.com Disclosure Number: IPCOM000049682D
Original Publication Date: 1982-Jul-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Franchak, NP: AUTHOR [+4]

Abstract

Available chip packages generally consist of a ceramic chip carrier with a lid which contains a chip that is hermetically sealed using a low melt gold/tin solder. Attachment to MC (metallized ceramic) substrates requires a higher melting solder which causes melting of the gold/tin solder during processing. This can cause movement of the lid and subsequent loss of hermeticity.

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Insuring the Hermeticity of Chip Packages

Available chip packages generally consist of a ceramic chip carrier with a lid which contains a chip that is hermetically sealed using a low melt gold/tin solder. Attachment to MC (metallized ceramic) substrates requires a higher melting solder which causes melting of the gold/tin solder during processing. This can cause movement of the lid and subsequent loss of hermeticity.

To prevent lid movement, chip packages are loaded into a suitable rubber block fixture containing shallow cavities approximately the same size as the chip package. The parts are precleaned with isopropyl alcohol. After drying, the parts are sprayed with an eleven-micron conformal coating of a polyimide. Next, the coated packages are heated to 100 degrees C for 15 minutes followed by 210 degrees C for another 15 minutes for curing. This leaves the parts ready for tinning and assembly to MC substrates.

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