This is a very big question. You will receive a lot of pro's and con's for each process. (I know I have my opinions) The best thing you can do is decide what you are looking for in a finished etched trace geometry. Process samples of different line widths and take many cross sections. When you take your cross sections you will want to cross section both top and bottom (horizontal) / left or right (vertical) of the substrate as it was processed as well as traces that are processed in parallel and perpendicular and at 45 degree angle to the direction of travel of the substrate as it was processed. When you read these cross sections you will be focused on what the sidewall characteristic is of the left and right side of each trace and how they relate to each other based on direction and position. With the these cross sections you must also look at the position on the conveyor top center bottom on vertical or left center right of a horizontal unit. Once you gather this data you can then determine which process will meet YOUR expectations. Include in this decision controlled impedance and very fine lines if this is part of your goal. When you measure the line widths make sure you compare the measurement to the exact location on the A/W that was used to image the test panel. Line widths on A/W vary and you want to remove this variation from your comparison. Because each shop's expectations are different each process finds it's own niche. Guy Willingham Zycon [log in to unmask] ______________________________ Reply Separator _________________________________ Subject: FAB: Horizontal versus vertical etching Author: [log in to unmask] at corp Date: 1/29/97 3:16 AM We would like to receive input on the positive and negative aspects of horizontal etching with oscillating spray bars, versus vertical etching of inner layers and outer layers using an alkaline etchant. We would like to hear of experiences as to which method provides the best results in terms of line width uniformity, top to bottom consistency, and conveying of cores as thin as .004 with half ounce copper on both sides. Panel sizes vary from 12 X 12 to 21 X 30. Line and spaces down to .004 X .004 for the smaller panels, .008 X .008 on the larger panels. Please presume that equipment of either type is well maintained and that the chemistry is under good control. Many thanks, Luis Rivera CompuRoute, Inc. Dallas, TX [log in to unmask] (214) 340-0543 *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * *************************************************************************** *************************************************************************** * TechNet mail list is provided as a service by IPC using SmartList v3.05 * *************************************************************************** * To unsubscribe from this list at any time, send a message to: * * [log in to unmask] with <subject: unsubscribe> and no text. * *************************************************************************** * If you are having a problem with the IPC TechNet forum please contact * * Dmitriy Sklyar at 847-509-9700 ext. 311 or email at [log in to unmask] * ***************************************************************************