Process flows for formation of fine structure layer pairs on flexible films
US6039889A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 12, 1999 |
| Grant date | Mar 21, 2000 |
| Priority date | — |
| Expiry date | Jan 12, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH05K2203/1383
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Processes for forming conductive vias between circuit elements formed on either side of a flexible substrate are disclosed. In one embodiment, the inventive process starts with a flexible film polyimide substrate on each side of which is arranged a layer of copper. Both of the copper surfaces are coated with photoresist. Blind vias are then drilled through the top copper layer and substrate using a laser. The photoresist is then exposed (patterned). A plating operation is used to fill the vias with a conductive material. The resist is then developed and the line and pad structures on the surface of the copper layer are plated. The photoresist is then stripped. In a variation of this embodiment, the photoresist is imaged prior to drilling of the vias using a laser. In an alternative embodiment of the inventive process, a through hole is drilled instead of a blind via. In either embodiment, there is no process step between the photo-exposure of the resist and the laser drilling which can impact the dimensions of the substrate.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.