Printed circuit surface finish, method of use, and assemblies made therefrom
US10902967B2 · kind B2 · utility
Inventors
Key dates
| Filing date | Nov 19, 2019 |
| Grant date | Jan 26, 2021 |
| Priority date | — |
| Expiry date | Nov 19, 2039 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K2203/122
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A surface finish for a printed circuit board (PCB) and semiconductor wafer includes a nickel disposed over an aluminum or copper conductive metal surface. A barrier layer including all or fractions of a nitrogen-containing molecule is deposited on the surface of the nickel layer to make a barrier layer/electroless nickel (BLEN) surface finish. The barrier layer allows solder to be reflowed over the surface finish. Optionally, gold (e.g., immersion gold) may be coated over the barrier layer to create a nickel/barrier layer/gold (NBG) surface treatment. Presence of the barrier layer causes the surface treatment to be smoother than a conventional electroless nickel/immersion gold (ENIG) surface finish. Presence of the barrier layer causes a subsequently applied solder joint to be stronger and less subject to brittle failure than conventional ENIG.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.