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Immersion Gold as a Sensitizer for Electroless Gold Plating

IP.com Disclosure Number: IPCOM000077658D
Original Publication Date: 1972-Sep-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 23K

Publishing Venue

IBM

Related People

Bakos, P: AUTHOR [+3]

Abstract

Patterned-chrome-copper-chrome metallurgy (Fig. 1) receives a protective edge coating of gold as in Fig. 2, in accordance with the procedure outlined below:

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Immersion Gold as a Sensitizer for Electroless Gold Plating

Patterned-chrome-copper-chrome metallurgy (Fig. 1) receives a protective edge coating of gold as in Fig. 2, in accordance with the procedure outlined below:

The gold edge coating serves to prevent copper migration at the edges, to prevent corrosion of the copper at the edges and to provide an optimum wettable surface for tinning at edge sites subject to soldering (e.g. for chip mounting or the like).

The procedure for gold deposition is:

1) Immerse part to be coated in SEL-REX* - low pH immersion gold bath (15 minutes at 160 degrees F).

2) Rinse.

3) Immerse part in electroless gold bath (15-60 minutes).

The immersion gold deposits only on the copper and, therefore, can be applied without masking of the chrome and exposed substrate. The electroless gold deposits exclusively upon the immersion gold. Being poorly adherent to copper, the electroless gold requires the immersion gold as an activation layer to secure suitable thickness of gold deposit with suitable adhesion. The requisite thickness for corrosion protection is formed by the electroless gold. * Product of SEL-REX Company.

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