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
     se cross sections you must also look at the position on the conveyor
      top center bottom on vertical or left center right of a horizont
     al unit.  Once you gather this data you can then determine which pr
     ocess 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]      *
***************************************************************************