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Electroless Copper Plating Baths

IP.com Disclosure Number: IPCOM000091293D
Original Publication Date: 1968-Jan-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Haddad, MM: AUTHOR

Abstract

This stable bath provides rapid electroless plating of relatively thick films of copper. The bath employed is an electroless process which requires no other catalyst. The copper deposit itself influences and maintains the deposition.

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Electroless Copper Plating Baths

This stable bath provides rapid electroless plating of relatively thick films of copper. The bath employed is an electroless process which requires no other catalyst. The copper deposit itself influences and maintains the deposition.

Copper can be deposited from the copper plating bath by the following reactions. If a plastic substrate is seeded with minute particles of catalytic compound, e.g., a palladium-stannous complex, the active sites of the catalyst become covered with copper. The copper deposit continues to build up, with the catalyst having diminishing influence.

The following bath is capable of continuing stability, a high rate of deposition, and the ability to form thick metallic deposits of relatively pure-copper, in the above reaction. Copper sulfate 7 grams

Rochelle Salt 75 grams

Sodium hydroxide 20 grams

Triethanolamine 10 milliliters

Sodium carbonate 10 grams

Sodium cyanide 0.125 grams

Formaldehyde 25 milliliters

Water to make 1 liter.

The concentration of the inhibitor NaCN sodium cyanide and the temperature of the bath influence the rate of deposit, stability, and autocatalyzing effect to produce thick deposits. The upper graph indicates the effect of the inhibitor concentration and operating temperature on the rate of deposition. The lower graph indicates the effect of adequate filtration and aeration upon the bath.

The bath has an optimum deposition rate of .2 mils per hour when operated at 52 degrees C. The d...