Hi John;
 
 One of the additional things that you will need is a 5% H2SO4 wash between 
 the developer and the etcher.  This will remove a conversion coating (think 
 it's a zinc compound) that makes the double treat more difficult to etch. 
 This is especially critical with fine lines.  The other problem that we have 
 run into is that the double treat, because of the surface topography, tends 
 to lock in photoresist and make it harder to strip.  Finally, make sure that 
 you have good drying through the wet chemistry steps (DES etc.)  the double 
 treat tends to take and show stains real well if left to air dry after any 
 of these operations.
 
 Hope this helps.
 
 Greg Schroeder


______________________________ Reply Separator _________________________________
Subject: FAB: Double Treated Copper
Author:  [log in to unmask] at SMTPLINK-HADCO
Date:    6/18/96 11:41 AM


Address,
 
We have a rep from EIS that is trying to sell us some Double 
Treated Copper (aka Trick-o-Treat Copper).  As with anything there 
are pro's and con's to materials.  I am slightly familiar with 
some of these pro's and con's of double treated copper, based on 
past readings.  What I do know about it:
 
1.  It eliminates Black oxide and Chemical/Mechnical Scrubbing 
    process
2.  Resist adhesion is improved due to the copper topography
3.  Handling parameters are increased prior to resist lamination
    (since there is no cleaning process prior)
4.  There are difficulties in AOI-ing the layers     
5.  Prepreg adhesion is improved at the lamination stage
6.  Is it true that new equipment is needed to process this 
    material?  EIS says no, but others I spoken with say yes.
7.  Is oxide necessary when processing double treated polyimide 
    layers.  RBO (Atotech) is a recommended oxide for polyimide 
    layers and improves prepreg adhesion?
8.  etc.,
 
Please add any additional information you may have that can help 
in our evaluation.  We have some double treated samples that we 
will be testing soon.  Thank you in advance.
 
John Gulley - PE
Dallas, TX