Process for providing bond enhancement and an etch resist in the fabrication of printed circuit boards

Abstract

A process for providing bond enhancement and an etch resist for a printed circuit board is provided. A sheet comprising at least a layer of copper is immerses in a first immersion tin solution comprising a tin metal and a complexing agent in an acidic medium for a time sufficient to deposit a first heavy tin deposit on the sheet. The sheet is then immersed in a second immersion tin solution comprising stannous tin ions and stannic tin ions and a complexing agent in an acidic medium for a time sufficient to deposit a second thin tin deposit on the sheet. The second thin tin deposit has a thickness less than a thickness of the first heavy tin deposit. A rough surface texture providing mechanical adhesion sites results. The board is then treated with a coupling agent, such as silane, for enhanced bonding to a subsequent epoxy or other polymer prepreg. Additionally, the first heavy tin deposit may serve as an etch resist in subsequent fabrication of the provided circuit board.

Dependencies are inferred from the claim text.