Susan,

     The outcome reliability is based on the PCB supplier you are using.

     Was the etch right; speed, replenish, nozzles, etc?
     Was there much undercut?
     Was too much buttercoat removed?
     What oz. Cu did they use?
     What's the customer design like?
     Did they evenly distribute copper throughout all layers?
     Are there isolated traces?
     Are they using Cupric Chloride or Ammonical?
     How thick are the layers, thin or thick core?
     Did the Photo Resist hold up in etch?
     Was the surface prep properly?

     These questions go on!

     Four mil lines/spaces are producible.  Be careful on who claims to
     produce such PCBs!  Some can produce these lines/spaces only in
     proto-type volumes while others are successful in medium production
     and yet others in high volume.  There pricing sometimes dictates the
     anticipated scrap.  Two to get one, 100 to get 100, 105 to yield 100,
     etc.

     If I looked hard enough I can resurrect some old documents on ESS
     testing with a wide variable of technologies.  Not sure what your end
     customer is trying to yield, more real estate, impedance
     characteristics, pushing the envelope, better routing, etc,.

     From my past experience, I recommend you request .004 mil lines and
     .005/.006 spaces.  This is a comfortable level of producibility and
     reliability provided by a wide range of PCB suppliers.  The spacing
     being the key here.  I'll see what I can to find supportive evidence.


     John Gulley - Process QE
     INET Technologies Inc
     "A Smarter Vision"
     1255 W. 15th Ste 600
     Plano, TX 75075
     972-578-3928


______________________________ Reply Separator _________________________________
Subject: [TN] 0.004" trace/space technology
Author:  Susan Harrington <[log in to unmask]> at Internet
Date:    11/17/98 8:58 AM


I have a customer who is skeptical of using 0.004" trace/space width
technology on their boards. Does anyone know where I could find
reliability study information on this subject? Both fabriciation and long
term.

Thank you-

Susan



__________________________________________________________________________
 _/_/_/_/_/    _/_/_/   _/_/_/               Susan Harrington
    _/      _/           _/                  PCB Designer
   _/      _/           _/                   Technology Group Inc.
  _/      _/  _/_/     _/         A          [log in to unmask]
 _/      _/    _/     _/        PLEXUS       920-751-5432 (voice)
_/        _/_/_/   _/_/_/       Company      920-751-5659 (fax)

__________________________________________________________________________

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