Biased acid cleaning of a copper-invar-copper laminate
US6179990A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 30, 1999 |
| Grant date | Jan 30, 2001 |
| Priority date | — |
| Expiry date | Jun 30, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K2203/105
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
A method for cleaning a copper-INVAR-copper laminate in an acid solution without inducing a galvanic etching of the INVAR. An initial step of the method forms a circuit element that includes a power supply, the laminate electrically coupled to a negative terminal of the power supply, and a conductive anode electrically coupled to a positive terminal of the power supply. The conductive anode may include a conductive material, such as titanium, that is preferably inert to an acid solution into which the laminate will be subsequently immersed. After turning on the power supply to a voltage between about 1 volts and about 10 volts, the laminate and conductive anode are immersed in the acid solution, so as to form a closed circuit with a voltage bias across acid copper-INVAR-copper interfaces. The voltage bias prevents galvanic action from occurring and therefore protects against galvanic etching of the INVAR. After the laminate has been cleaned by the acid solution, the laminate is removed from the acid solution and the power supply is turned off. The laminate may also exist as an internal layer of a dielectric substrate, wherein the substrate is immersed in the acid solution, and wher…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.