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Metallurgy Rework Technique for Semiconductor Devices

IP.com Disclosure Number: IPCOM000049151D
Original Publication Date: 1982-May-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

Grosewald, P: AUTHOR [+3]

Abstract

This is a technique for repairing defective solder balls used for joining semiconductor integrated circuit chips to substrates.

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Metallurgy Rework Technique for Semiconductor Devices

This is a technique for repairing defective solder balls used for joining semiconductor integrated circuit chips to substrates.

In commonly known "flip-chip" technology, an individual semiconductor chip 10 is provided with hundreds of solder balls 12, placed on chip terminal metallurgy known as ball limiting metallurgy 14. Such a chip 10 is placed up-side down (hence "flip-chip') on correspondingly positioned terminals of a ceramic or plastic substrate, and heated to form an electrical/mechanical connection.

Whenever one or more solder balls 12 are defective, an effective connection to the corresponding substrate terminal cannot be made. A solder ball 12 is defective, for example, if it has an insufficient volume of solder, or if it is deformed. The ability to repair or rework defective solder balls 12 is essential for salvaging the chip. As illustrated in Fig. 1, an individual defective solder ball (not shown) has been entirely removed from its supporting metallurgy 14' with a diamond chisel or other suitable micro tool under a microscope. As shown in Fig. 3, a new solder ball 12' having the same metallic composition and volume as the good solder balls 12 is then placed on metallurgy 14'. An appropriate heating process (through the customary reflow furnace) attaches the new solder ball 12' to metallurgy 14', completing the repair. In order to assure that the solder ball metal composition and volume are precis...