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Browse Prior Art Database

Method of Reducing the Formation of Copper Nodules in an Additive Plating Bath

IP.com Disclosure Number: IPCOM000042895D
Original Publication Date: 1984-Jun-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Schuster, U: AUTHOR

Abstract

The formation of copper nodules on inactive surfaces of nonmetallic substrates during the deposition of copper on activated surfaces and metal substrates is reduced by introducing air into plating bath before the heat exchanger is used. During the deposition of copper in a chemical bath, the following primary reaction occurs: (Image Omitted) . In addition to this reduction of Cu2+ by formaldehyde, there are secondary reactions, such as the incomplete reduction of the Cu2+ to Cu2O and the disproportioning of this Cu-I-oxide to Cu2+ and elementary copper. The copper formed during this process is deposited in the form of nodules at undesired points on the non-metallic surface.

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Method of Reducing the Formation of Copper Nodules in an Additive Plating Bath

The formation of copper nodules on inactive surfaces of nonmetallic substrates during the deposition of copper on activated surfaces and metal substrates is reduced by introducing air into plating bath before the heat exchanger is used. During the deposition of copper in a chemical bath, the following primary reaction occurs:

(Image Omitted)

. In addition to this reduction of Cu2+ by formaldehyde, there are secondary reactions, such as the incomplete reduction of the Cu2+ to Cu2O and the disproportioning of this Cu-I-oxide to Cu2+ and elementary copper. The copper formed during this process is deposited in the form of nodules at undesired points on the non-metallic surface. To prevent the disproportioning of the Cu-I-oxide, air is introduced into the additive plating bath, with the aerial oxygen reoxidizing the Cu1+ to Cu2+ . However, as most of the Cu1+ is produced in the heat exchanger as a result of overheating, the air, rather than being fed to the plating bath together with the chemicals, is introduced, as illustrated, before the heat exchanger is used. In this manner, the dissolved aerial oxygen is capable of oxidizing the Cu1+ before it becomes disproportioned to Cu2+ and elementary copper.

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