This is a generic problem with all CAM packages. We continually fight 
     this ourselves, day in and day out. I have been working with Valor to 
     fix this and CiruiTest Fixpert. We used to use Orbotech and IGI for 
     this, but with the same results. Every fabricator that I have visited, 
     or talked with, also has a similar problem. But, we all say we perform 
     "100% netlist test".
     
     I'd love to compare notes with you sometime on this. I think we need 
     to address this as an industry. I have been working with the CAD 
     software suppliers to raise their awareness of what a test point is. 
     It turns out, they don't really have a clue.
     
     The current IPC-356 does not properly define all conditions of test 
     points. There is a new revision that is currently out for member 
     approval which corrects known deficiencies.
     
     I am not aware of any software package in the world, or other worlds, 
     that can prepare a proper netlist for test. I am also not aware of any 
     OEM's who use a CAD package, this includes Mentor and Cadence, that 
     can consistently create a perfect netlist for test.
     
     If we want to get to basics, this industry doesn't have a common 
     definition of what a test point is. We also need a common definition 
     of what "100% netlist test" means. I have a quiz that I have given to 
     30+ knowledgable test people (including customers) which shows a 
     sample PCB. I ask them how many test points to they see? No one has 
     given the same answer, let alone what I think is the correct answer.
     
     Reply back by e-mail, or give me a call.
     
     What do the rest of you think?
     
     
     Dana Korf
     Dir. Engineering Services
     Hadco, Santa Clara (formerly Zycon)
     [log in to unmask]
     


______________________________ Reply Separator _________________________________
Subject: Everrett Charles 9090 Test Fixtures
Author:  [log in to unmask] at corp
Date:    5/16/97 3:08 PM


     
We have an Orbotech Xpert 1700 CAM station from which we are generating 
IPC-D-356 (netlist) and NTD (net trace data) files. We then take this data 
and use the Everrett Charles ValueGrid software to generate the drill files 
required to build the 9090 test fixtures.  We've found that there is an 
incompatibility between these two software packages. The end result is a 
test fixture with missing test points due to confusion between midpoints and 
endpoints of the two software packages.
     
This problem happens frequently when there are via holes in, or partially 
in, a surface mount pad.  The Orbotech software sees the center of the SMT 
pad as a midpoint and the via hole in the SMT pad as an endpoint, the 
opposite of what I would expect. The ValueGrid software drops the midpoint 
and thus the SMT pad and also drops the via hole in the SMT pad because it 
assumes that the via is a midpoint. Again the end result is a missing 
endpoint.  
     
Does anyone have this same problem?
     
Does anyone know of software that can generate the drill files necessary to 
build Everrett Charles 9090 test fixtures from raw gerber data without the 
problems listed above? 
     
     
If so, please contact me.
     
     
Sid Tryzbiak
VP Engineering
Continental Circuits, Inc
407-699-5000
     
     
     
     
     
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