Browse Prior Art Database

Soldering to Electroless Nickel

IP.com Disclosure Number: IPCOM000089711D
Original Publication Date: 1977-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Stelmak, JP: AUTHOR

Abstract

Electroless nickel, deposited from a bath containing hydrophosphites, can contain as much as 7-10% phosphorous, which can interfere with soldering (e.g., Pb-In) applications thereto. Thus, the phosphorous content must be kept low to obtain good bond strength.

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Soldering to Electroless Nickel

Electroless nickel, deposited from a bath containing hydrophosphites, can contain as much as 7-10% phosphorous, which can interfere with soldering (e.g., Pb-In) applications thereto. Thus, the phosphorous content must be kept low to obtain good bond strength.

In this process, the phosphorous and carbon content of electroless deposited nickel layers can be reduced in a two-stage treatment comprising a first step of heating for about one-half hour at about 700 degrees C in a wet 90-10 forming gas mix (water saturated at 45 degrees C), followed by about a 15-minute exposure in a dry oxygen-free forming gas at the same temperature.

It is believed that the phosphorous migrates to the nickel surface where it is oxidized (in the wet forming gas) to form volatile compounds, which are removed in the gas atmosphere. Some oxidation of the nickel takes place during the initial, first heating stage, but is reduced in the second dry forming gas treatment. Carbon is similarly removed from the electroless nickel layer by the wet-dry forming gas heat treatment.

The overall result is a denser, purer nickel layer with enhanced solderability.

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