Hi Eric,

believe it or not I had the same problem and I solved it only by closing any fume extraction after the etching and replenish chamber.
I suppose the dry film was brake down from ammoniac fume that from the etch and replenish chamber was aspirate into the rinsing chamber.
Moreover, as first step I only had replenish directly in the etching chamber.

Good luck
-----Ursprungligt meddelande-----
    Från: Eric Masters <[log in to unmask]>
    Till: [log in to unmask] <[log in to unmask]>
    Datum: den 6 april 2001 01:46
    Ämne: [TN] Dryfilm breakdown in Ammoniacal etch
    
    
    I am having some difficulty with dryfilm breakdown on heavy copper etching.   
    I have tried a number of different films, and they all work on copper weights 
    less than 3 ounces.  Above three ounces, I begin to have breakdown issues in 
    the etch replenisher chamber. 
    
    I have maximized all the process parameters for dryfilm:  surface prep, 
    lamination exit temperature, exposure, and developing.  I am convinced that 
    the problem lies with the etching chemistry, but I'm not sure what parameter 
    contributes most to breakdown.   
    
    Does anyone know which component is the most troublesome?  or is it a 
    combination of things?  I've tried varying pH, copper concentration, 
    chlorides, and controlling free ammonia in the replenishment chamber.  Any 
    suggestions will be appreciated.   
    
    Thanks.