Process for fabricating multilayer circuit boards
US4775444A · kind A · utility
34Cited by
13References
14Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Aug 26, 1987 |
| Grant date | Oct 4, 1988 |
| Priority date | — |
| Expiry date | Aug 26, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K2203/072
- WIPO fieldSurface technology, coating
- WIPO sectorChemistry
Abstract
Printed circuit boards having copper circuit patterns coated with an adhesion promoter (e.g., copper oxide, tin) are subjected to the action of an aqueous chromic acid solution prior to incorporation in a multi-layer board by interposing layers of semi-cured polymeric non-conductive material between the individual boards and laminating the assembly using heat and pressure. The chromic acid treatment serves to improve adhesion between the layers and, in particular, to overcome or minimize the "pink ring" effect which is frequently observed around holes drilled through multilayer boards.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.