• Simplifies multilayer processing and improves yields.
• Eliminates pumice cleaning, mechanical scrubbing and microetching.
• Improves etching and higher innerlayer yield.
• Improves oxide processing and reduces waste disposal.
• More reliable performance with less pink ring.

Overview
Reverse treated copper foil is manufactured by applying copper nodularization, brass thermal barrier and passivation to the shiny smooth side of the foil rather than to the roughened matte side of the foil as is done when manufacturing conventional or standard copper foil. A thin layer containing only passivation or antioxidants, which is normally applied to the shiny smooth side of standard foils, is applied to the roughened matte side of reverse treated foil. The fully treated side is laminated to a prepreg leaving the roughened matte side of reverse treated foil available for innerlayer processing. The reverse treatment is offered in both Grade 1 RTC multipurpose foil and Grade 3 RTCS foil for multilayer circuit boards.

Side Exposed to Photoresist			Side Laminated to Prepeg
RTC	Standard Foil		RTC	Standard Foil
The already roughened surface of reverse treated foil eliminates the need for costly aggressive roughening of the foil surface.			The low profile structure of RTC Foil provides more vertical, cleaner etching and better control of dielectric thickness of thin laminates.

Advantages

• Eliminates Costly, Aggressive Roughening of the Foil Surface – Reverse treated copper foil eliminates the need for aggressive precleaning of laminate with pumice, mechanical scrubbing or microetching. A simple wash with 10% sulfuric acid removes the passivation leaving the roughened matte surface available for photoresist processing.
• Cleaner Etching and Higher Innerlayer Yield – The lower profile of RTC foil compared to standard foil provides faster, cleaner etching with more vertical sidewalls. Innerlayer yields with RTC can be higher due to the cleaner etching and less undercutting of photoresist.
• Simplifies Oxide Processing and Reduces Waste Disposal – The already roughened matte surface of RTC foil eliminates the need for microetching or roughening during oxide processing. The costly waste disposal associated with microetching is, of course, eliminated with RTC foil.