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Browse Prior Art Database

Composition for Oxide Removal from Copper Surfaces

IP.com Disclosure Number: IPCOM000094138D
Original Publication Date: 1966-Jun-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Underkofler, WL: AUTHOR

Abstract

Oxides are removed from copper printed circuit card surfaces prior to immersion tinning by the following solution: Thiourea 100 grams Hydrochloric acid 124 milliliters Water 1 liter. The complete cleaning process is as follows: 1. Immersion in hot alkaline cleaning solution. 2. Water rinse. 3. Immersion in 20% HCl. 4. Water rinse. 5. Immersion with agitation for 1-2 minutes in the solution described above at 60 degrees C. 6. Water rinse.

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Composition for Oxide Removal from Copper Surfaces

Oxides are removed from copper printed circuit card surfaces prior to immersion tinning by the following solution: Thiourea 100 grams

Hydrochloric acid 124 milliliters

Water 1 liter.

The complete cleaning process is as follows: 1. Immersion in hot alkaline cleaning solution.

2. Water rinse.

3. Immersion in 20% HCl.

4. Water rinse.

5. Immersion with agitation for 1-2 minutes in the solution

described above at 60 degrees C.

6. Water rinse.

Step 3 removes most of the cupric oxide. Step 5 removes the residual cupric oxide and also cuprous oxide. The inclusion of thiourea in the oxide removal solution reduces undercutting and results in a milder etching action producing smoother copper surfaces. These can be coated with immersion tin in shorter dipping times.

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