Innerlayers made with drum side treated foil still require an oxide process prior to multilayer lamination. You may be thinking of double-treat coppper, which eliminates the need for oxide. Your laminate supplier should be able to provide you with data on double treat copper. Drum side treated foil, which is being offered on laminates by most of the major laminate manufacturers (it is sold under various names; DSTF, MLF, MLS, etc.), has some advantages over standard copper. Resist adhesion is generally better, and cleaning is somewhat simpler, with little or no microetch required. Depending on your process, you may see increased bond strength after multilayer lamination with drum side treated foil. Again, your laminate supplier should be able to provide data. Mark Dowding Regional Technical Specialist Insulectro