Re: sporadic non-oxiding of copper We have seen this, and have done some significant research into the phenomenon. It is clearly not a cleaning problem, as the non-oxided areas tend to be very regular in their pattern. Also, we have cleaned and microetched to the point that we removed more than 50% of the thickness of the Copper, with no change in the oxide pattern. It would appear to be some Copper chrystalization problem, with some areas of the Copper becoming cathodic, or in other words reduction sites for the Chlorite in the oxide solution. This is the only explanation that we came up with that made sense, as the problem areas would eventually oxide completely, but would take about 50% longer to get full coverage as the rest of the Copper. We also noticed that the problem was definitely related to the Copper source, and by changing source, the problem would go away completely. This lends credence to the idea that the problem is related to the chrystallinity of the Copper. In a related area, a paper was presented to the Electochemical Society last spring that discussed differences in etching characteristics (speed, and etch factor) due to differences in chrystal structure in the Copper substrate. If there is interest, e-mail me back, and I will provide details on who did the paper, and what the title was. Rudy Sedlak RD Chemical Co. fax 415-962-0370