Neutralizing chloride ions in via holes in multilayer printed circuit boards
US4398993A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 28, 1982 |
| Grant date | Aug 16, 1983 |
| Priority date | — |
| Expiry date | Jun 28, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K2203/1388
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A neutralization process is provided for neutralizing chloride ions in etched via holes in multilayer printed circuit boards. The process comprises two dip operations of the board in a Neutra-Clean and water solution which is continuously re-circulated. This is followed by subjecting the board to a heated de-ionized cascaded water feed, an ambient overflow de-ionized water rinse, and conveyorized air drying. The Neutra-Clean solution has the ability to penetrate down to the bottom of the via hole and to attract the free chloride ions from the etchant residue. The de-ionized water feed and rinse steps rinse out and remove the Neutra-Clean solution and any residuals formed by chemical reaction.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.