Methyl chloroform-free desmear process in additive circuitization
US5311660A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 10, 1993 |
| Grant date | May 17, 1994 |
| Priority date | — |
| Expiry date | Feb 10, 2013 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10T29/49165
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Disclosed is a method of drilling, desmearing, and additively circuitizing a printed circuit board. The printed circuit board is drilled under conditions which produce glass and polymer smeared vias and through holes. The particulate debris is removed by vapor blasting the drilled printed circuit board. Next the printed circuit board is soaked in a solvent to swell the drill smear on the circuit interplanes of the printed circuit board. This solvent is then removed by entrainment in a gas, and a stream of an aqueous, acidic, oxidizing solution is passed through the printed circuit board holes to remove swollen smear in the thru holes and produce an etchback of conductors. After a water rinse an aqueous reducing solution is passed through the printed circuit board to reduce and remove aqueous acidic oxidizing solution, e.g., residual aqueous acid oxidizing solution. The printed circuit board is rinsed to remove the aqueous reducing solution. The surface of the printed circuit board is then seeded, the intended circuitization is photolithographically defined on the printed circuit board, and the circuitization, including the surface circuitization and the plated through hole circuiti…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.